I am so impressed with what you have done for the foam board plane construction. I admire your spirit of giving and your support of FliteTest. In my mind, you are the reason I built my first plane and will ever be thankful to you.
Ed--Thanks so much for a well thought-out test series! Not only the test methods, but your narration is always precise and shows your intelligence and education IMO. My personal (and ongoing) experience with DT foamboard is that the bonding of layers of the board with hot glue creates unnatural increases in strength; it's as though the hot glue becomes a structural member, with the foamboard acting as a shear web and forcing the hot glue to maintain its column orientation and strength. Thanks again and keep up the great work--I know I'm reflecting appreciation of the whole RC flying community here!
I've been experimenting with building these wings using carbon arrow spars and 3D printed ribs and I've had a lot of great success. The nice thing about including ribs is they result in a very nice accurate airfoil every time. I've also created a host of 3D printed parts for the fuselage including motor mounts, wing mounts, bulkheads, etc.
Carbon arrows from Walmart are way cheaper than carbon tubes from a hobby store . I like to walk around stores and look at everything and think about how I could repurpose it
Thanks so much for the video! I used your design to build a 60" wing for a Timber plane that I built. I didn't use any wood spar or support bar and it worked well, my wing was strong. It even held up well in the wind. I just posted a video of my building that plane, if you want to see your experiment in action!
Just getting into it with my grandson. I have built and flown balsa wood planes decades ago all glow with old AM electronics. I have been following Fllight Test for years but I found you and am going to build you r plan first. It looks great to me and should be quite easy to control. Thanks your boss rock.
I was about to post a comment asking if flite test had seen the vid. Then I wisely kept reading to avoid appearing stupid and sure enough there it was. It was a combination of EA and FT that actually got me into model aviation. Keep it up you guys :)
Ed, love the video's. Keep them coming. There are a few FT designs that use a stacked EA spar. The FT Simple Soarer comes to mind. That is by far the best choice of spar for a constant chord, constant thickness, zero sweep wings. Building a spar on edge is used to facilitate ease of construction for taper and sweep. The real benefit in the EA wing build is the efficiency. Build a motor glider that is a cross between a Nube Tube and a Simple Soarer. Then fly it with a 60" wing built EA style then a 60" 3 break FT Style wing. Keep the chord the same for both wings. You will see how slippery the EA wing is compared to the 3 break wing. I would like to see you develop an EA style tapered wing.
Great testing! It was systematically performed and well tested for various factors... Well Done! Conclusion: Horizontal-stacks of foam provide for more foam/paper mass to take more stress/load than the I-beam, given the mass of I-beam is significantly low. Future testing: If weight of spars don't account for much in overall wing then stacks of I-beams (vertical stacks) of similar dimensions (l x h x w) to those of horizontal stacks should be constructed and tested. Hypothetically, this method would provide even more strength and can take more load as this construction would counter for more compression stress on top and stretching on the bottom. It would also provide for more direct comparison as to which method is better since the mass is now constant!
ED! Come back! Just show off builds and do flying videos, enough people will share to large Facebook groups to give questions/ideas for other new videos. Your my recommendation for every pilot/builder looking for a place to start. 👍
Brilliant analysis. Thanks. Every wing I have folded did so near the fuselage where most of the load is. I have now used a modified FT spar with a 1/32in card stock laminated to the top surface of the spar for 1/3 of the wingspan. It adds very little weight and strengthens the compression zone. I usually don't have a problem at the tension side but add packing tape adjacent to the spar on the bottom inner face, again only for about 1/3 span. Adds strength and keeps weight down. I'm going to try your type spar as well but I might cut out the inner laminates halfway out to reduce weight but keep the full buildup at the high load areas. Thanks again. I enjoy watching and learning from your videos.
It seems like the common weakness of foam board is in compression. perhaps an extra thick layer of hot glue could be applied between the top of spar and the inside surface of the wing to add compression strength. Also, I've had good results with applying a strip of EPT to the bottom of the wing, with the EPT under tension (bow win up, afix EPT at ends of win, release, smooth EPT down). The simulated crash failure mode of your EA spar stack (breaking the bottom wing skin) would seem to suggest the value of this addition. Thanks for your Testing, your are a true friend of RC Flite!
Super stuff. A spin on your great discussion is to add tension resistance with a carbon L spar. Take a 8-12 mm square tube, slice the tube such that you have two L shaped carbon spars and use one of the L shaped spars with the Flite Test spar. Works great and better crash resistance. Also, use high expansion spray insulation foam inside the wing, forward of the spare. Again, improved crash resistance. Because, when I crash its high impact....:o)
Hi - I'm a 'Flite Test' spar builder, but I early-on started adding a 2.0 mm - 2.5 mm 'steel reinforcing wire' embedded in the centre of the spar and across the middle third of the wing. I started doing this because many of the wings I build into my planes have dihedral - which in basic engineering terms, is like telling the wing exactly where to fail! :) The wire adds strength but allows some flex, complementing the foam. Also to my way of thinking; if the hold-down elastics or mechanical fixings of the wing to the fuselage are firm enough, this engineering problem is better considered as a half wing acting as a cantilever projecting from a fixed point (the edge of the fuselage or elastic.) Considered this way, the forces acting at the fuselage are an accumulation of distributed bending moments, which all concentrate at the wing root. For me it is about considering at what point the wing 'needs' the extra strength. Anyway - which ever way you approach the problem, the area that fails is the centre of the wing, so that's the bit that needs to be stronger. Maybe there's room for a hybrid wing that uses an EA centre and Flite Test outers? Also I wonder if the 'other option', of laminating a spar vertically from sufficient elements to equal the width of the EA wing spar, would have out-performed the EA spar? I've a sneaky feeling it would have, but concede it would be a nuisance to build it up and get the top and bottom edge flat. Great work though, as always. Alibopo.
flite test outers obviously should increase the strength of an EA beam or even added to the flite test beam just because of the additional mass.. but so would tape...but the carbon rod is 10x greater than both and is easier to install in the EA wing.. nothing beats that except maybe an iron i beam
The Steel Wire, or even Aluminium Mesh, applied to the lower panels of the Dihedral Wing with a layer of Hot Glue smoothed over it, has made my Simple Cub nearly indestructible in high G Maneuvers. 😎 You do this of course, before folding over the top portions of the Wing. To solve the most obvious issue... Add more weight - add more Power!
Great video - thanks for taking the time to investigate the pros and cons of both approaches. Interestingly the FT Mini Mighty Arrow uses a tapered C-shaped box spar that accommodates the servo. I'd be interested to understand how this fairs compared to horizontal or vertical foam stacking.
Very interesting, I've been playing with using pink foam from Home Depot as my spars instead of the Dollar Tree Foam. The pink foam appears to be stronger. I do sand the pink foam edge to help the Dollar Tree foam fold over. Basically instead of having 3 pieces of foam I have one. I can drill the end to place a carbon spar into the pink foam, thus giving me even more strength. Just my two cents. Great video Ed!!!
You are correct, the pink Corning's foam board is stiffer and easier to "crack" if you cold roll the 1/4" thick option. If you are using thicker, you cannot shape it by cold rolling without defects and have to shape it in other ways.
great testing Ed man, engineers for life lol. Blooper rolls my man, everyone likes seeing people goof up, add one here and there. Flitetest taught me a lot about RC building, but you think like I do, efficiency is key, and I feel compelled to support your channel. keep up the good work!
Great video Ed. Thanks for doing the research and sharing. I was curious about your statement that both airfoil shapes were probably equal aerodynamically. So, I put both into Xflr5 (which uses xfoil and is designed for low-Reynolds number analysis). Turns out the EA airfoil is quite a bit better. At Re of 100,000 (roughly 25mph for a 5"-chord wing), the EA airfoil has a peak lift/drag ratio of 42 while the FT airfoil's peak is 25. That's a pretty significant difference and it's almost all due to drag. Even if you figure the wing drag is only 1/4 of the total aircraft drag (rough guess), that's still about a 10-20% overall drag reduction. All else being equal, that translates to a couple extra minutes of flying time on a 10-minute flight (plus, it looks better while doing it).
+Andy Roesch I knew intuitively having big ridges on the LE section of the wing would hurt L/D but almost 2:1 ratio wasn't what I expected. great to hear this, as I've been advising against flite tests wings since they started doing them, there's pretty much no benefit to having the ridges on them.
I too prefer the smooth airfoil as in the Armin wing. The 'facetted' Flitetest method looks a 'little-bit' strange, true. But it works. And works pretty good for a quick-n-simple foam build. One major advantage it has is its ease of construction for very young hands... Once I realized that, I became quite impressed!
There is actually strength benefits to having the ridges. Many of the 'features' (folds and bends) you see on car panels serve an engineering role as well as a cosmetic one, they help stiffen and strengthen the panel. Often the rounded shell of a wing is just a skin over an internal structural arrangement. You see this in balsa frame type models. Foam board wings are closer to the monocoque construction. You see this used in most modern cars, where the shell provides much of the strength. The most obvious example of the fold providing strength is the Old Fogey single fold type wing. This is tremendously strong due to the single 'CG' apex 'fold' in the panel. Even more strength is added by the outer wing dihedral elements, which effectively lock the ends of the flat central wing into position. Swings and roundabouts, but those folds do serve a purpose.
Everyone gets caught up in what type of spar to add to a plane, but they always seem to forget or sometimes ignore the tape spar. The concept of the tape spar is to apply one to two strips of tape along the top and bottom of the wing over the spar. As flex is induced into the wing, the surface tension of the tape helps prevent the foam underneath it from flexing as much as it normally would. On an EPO or EPP foam wing this can substantially stiffen a wing from flexing under heavy loads or high G turns. With flat foam planes that are coated in packing tape as a sealant or for color, the effect is multiplied by every strip of tape added, especially if there is a lot of overlap. That being said, I still try to add a single layer of tape along the spar line on the inside halves of the wing. If its a lightweight bird, I use normal packing tape. If its something a little larger, I use the extreme tape. When the tape spar works, it works well. The only real penalty is a tiny bit of extra weight. The only major caveat to the tape spar (tape in general) is its ability to adhere to the build surface. EPO and EPP foam can flex enough to pop the tape loose and that pretty well negates the benefits of the tape. Depending on the plane, that flex may occur more often than not, so it may be not be a good long term build method. On flat foam that has a paper coating you're left at the mercy of the adhesive used to bond the paper to the foam. With repeated exposure to humidity, hangar rash, general handling, and less than stellar landings the foam and paper usually part ways taking the tape away with it. I have tried removing the paper and applying the tape directly to the foam. For whatever reason, the tape just does not like bare foam. Ive tried several different types of tape and while some stick better than others, none of them bond very well with it. I found that Gorilla tape sticks very well, but at the cost of a huge weight penalty. There is always spray adhesive. The only issue with that is the mess and hassle of trying to apply tape to a surface that is constantly trying to apply itself to you, and the fact that if your not careful the spray will eat your foam. My shop is still a mess from the last time I used it. Everything is coated in a sticky film and that has been well over a year ago. Thanks 3M for making a superior glue. lol. All of that to say, when you build your plane and your about to start adding your internal spars, consider adding a few extra strips of tape along the spar line from end to end, especially if youre not going to be using tape to pretty up your bird. It can greatly reduce the flex in your build material and it will help reinforce your spar. As evidenced by his experiment, even adding tape to the spar increases its strength.
VERY interesting video, I wonder what's the impact of even-tamper curved profile of the experimental airline vs the hard edges of the flite test wing on the overall wing strength. Thanks for sharing
I watched this video with interest. Although I don't fly winged aircraft, I flew control line stuff back in the late '60's as a kid and was mentored by some old McDonnell Douglas engineers. They stressed strength to weight highly, and it has influenced everything that I have build since then. The one test that I wanted to see was your EA 3 ply spar turned on edge like the Flite Test 2-ply spar. My curiosity leads me to think a well adhered laminate would bring more of the I-beam strength to the study. Two thoughts, how are you adhering the foam layers, and how about cutting the spar after the glue has dried. I'd like to see if the paper layers plus the adhesive are stronger in the vertical application. My hobby has been woodworking for the last 30+ years, and it's usually true that if a structural support is wider than it is tall it is almost always stronger in the vertical orientation. The only issue I am concerned about is finding a glueing technique that is light enough that yields a good bond that isn't brittle. The one product that I can think of right now is Titebond makes a liquid hide glue that is used in wood veneering that is tough, thin, and has a long "open" time to give you time to align the poster-board while both bonding sides are still wet enough to flow to eliminate most of the air. I think it might be worth a try. Hey, if it intrigues you perhaps one day you might try it. You already have some much data collected, it might be worth that addition. I like to hear your thoughts. You have certainly provided a thoughtful presentation. Thanks !
Your curiosity has some good points and when it comes to foam board glue, Gorilla glue that foams is hard to beat. My acid test for foam board glues is the butt joint. It is one of the weakest joints we use in the hobby and can make or break the usefulness of a glue real fast. There are all kinds of disciples dedicated to a specific glue and they make videos to give praise to their choice, but I have noticed they tend to avoid showing the butt joint test, or how much glue they used. How long that glue remains useful is another detail few are concerned with since most of their models are flown for a season, or two and abandon for a new project. As to the foam board, remove the paper skins first and save a lot of weight. The glue used does most of the work since the foam is just a space filler. Any coatings applied help the foam survive longer and have to be lightweight, or the construction has to be more than foam and thin balsa, other materials, and plywood.
Seems pretty clear: Overall performance - lower weight with better yield goes to FT design. Which is easier to build is rather subjective - I'd go with either. But, how many wings fail mid-span on an even spar? None for me. Wing joints, etc, are where the issue typically falls, and the entire chord design is crucial, including spars, etc. Thanks for the analysis.
What Ed didn't talk about all that much is how the carbon fiber tube does the lion's share of the wing support to prevent failure and the only thing the foam does is trap it in place. A significant design detail that wasn't point out well.
I like that you tested this different forms of wing spars and I have bad experience with the flitetest spar made out of 6mm depron (had to put carbon in an FTCruiser as the wings were flopping around). But the efficiency of stress vs weight should be way better with the flitetest design. And you applied the extreme packing tape on the FT + versions on the wrong sides of the spar. The thought of an I-Beam is that the Compression and Tension only gets taken by the outer foils which in our case is the wing surface. Packing tape in itself can only take tension forces. Because of that the extreme packing tape should applied horizontally on the outer surfaces of the spar or if possible even on the wing surfaces as they are further from the mid of the spar and therefore can take more tension. If you fly scale and never do negative g manovers it would be enough to put the packing tape on the lower side of the wing. As it will only add weight if you use it on top and not take any compression. If one needs more strengh then the flitetest spar method allows it would probably best to put another spar in another region of the wing, trying to use more surface area of the wing to put tension and compression in. Or make hybrid of both designs using only flitetest spar in middle but adding a strip of foam on each surface as extra layer to take more compression forces. Nonetheless like you said your method is the easier one to build and looks way better and in reference of simple build designs which can take higher forces, yours will win. Also I may be wrong and the compressibility of the foam may already begin to matter, as I learned this stuff with with metals and not foam and you have way more experience with that. At this point they type of foam and it's orientation of use could actually already matter as the same foam can take way different forces depending of direction of use (depron is really floppy in one direction and way more stiff in the other) I hope I gave some good ideas, keep going with this channel. I really like it.
Now that was in depth, I have wondered for a while how much stiffness the carbon spar gives me, (a whole lot it turns out!) now I wonder about vertical plywood, aluminum angle, and carbon strip.. another video?
Great video as always. I think the FT "faceted" wing design has an extra feature that was missed. When making the wing, I always glue the facets in one glue operation and then the leading edge and spar in a second operation. I do that because its way more complicated to glue so many joints at once without screwing something up. It always surprised me how strong just the faceted top wing section was without the spar. I don't think a second video is required, but i'm curious what the strength difference is between the curved EA top wing plate and the faceted/glued FT top wing plate. I don't use much glue in the faceted joint but i'm sure it helps with the overall strength. Keep up the good work!
thank you for this really detailed and professional video, very helpful indeed. Just wanted to ask you, is foam board better or depron. thank you again.
hard wood is more expensive than foam board, and harder to come by for most people. And since you're already building the surfaces with it, you already have it (foam board). Foam is typically lighter as well.
You could use both versions and have an even stronger albeit heavier wing ...ea style spar for a forward spar and a ft half spar as a rear spar...depending on your wing size of course
Hola desde España. He aprendido mucho de tus videos yo también me dedico a este fabuloso mundo del aereomodelismo. Darte las gracias en primer lugar por todo lo q haces por este canal.... Me gustaría por favor q me dijeras donde puedo comprar el material q tu unas en tus proyectos y sie podruas pasar las medidas del phanto q tienes. Muchas gracias de nuevo.....
Great informative video thank you, what about a triangular foamboard spar? it might not form the aerofoil as nice as the Flat stack EA spar but I think the strength would be better.
Im new to making rc planes and drones, but i was just wondering, imagine battery wasnt a issue, would the gps of the rc plane/drone have signal world wide? Even 9000km out? Or does signal have a limit?
I've been experimenting with various sizes of 36" long Balsa sticks ranging from 3/16" x 3/4" up to 3/8" x 1" with beveled upper edges and a bead of Foam-Safe CA glue on the top and bottom. Once the glue impregnates the wood a bit and dries, it creates a super stiff layer. It's surprisingly strong, if a little heavier than a DTFB spar. I'd love to see a strength comparison of that against an EA style spar. I definitely need to remove the paper inside mine though. Getting a smooth curve is nearly impossible otherwise.
Very informative. Personally, I think your design is better simply because it is easier to construct and because it is stronger. Also, your wings are a lot more compact and sleek compared to some of Flite Test's designs, which means there's probably less drag on your planes. Can't say for sure without wind tunnel tests or scientific trials though, but that's what my intuition tells me.
I have found the strength of the wing doesn't depends alot on the spar. it's the fold on the foam. But all in all, wonderful video Ed.. hope to see many more.
+Mr. Sparkle And I also meant to say....both designs are superb but have different applications as you said. I wonder how a 'filled I-beam' would perform....
Hi, I have been playing with incorporating the Plastic strapping you get round big packages, bricks etc into my spars with some good results. Hot glue however isn't compatible with these materials and so I have been using gorilla glue. It adds a lot of strength and little weight.
Ed - Have you considered an alternate method of covering using craft paper & glue? Instead of packing tape on the outside, use brown craft paper saturated with white glue diluted 50% with water. I'm curious what the weight, tension, compression and crush load differences would be using this method over the FT method of leaving the paper on the foam board and your method of using packing tape covering.
Some designs use the triangle spar, but it does use more foam strips unless you only use two and use the wing inner surface to finish the triangle. Other designs use a modified triangle by inserting a strip of foam in a box, giving two triangles side-by-side. The basic feature most are trying to make use of is how a triangle will resist twisting, or warping until the material it is made of, or glue bond fails.
The EA design is good but if you turned the spar 90 degrees so the glue edge was up and down instead of front and back that would I'm sure make a tougher design, Thanks Ed for yet another great video. Now go and do some flying.
ive been making my spars using a pallet strapping sandwich.. strap/foam/strap.. this gives a very strong spar...the straps can be fixed on the spars or on the outside of the wing..
+John Reap RC Planes the straps can be fixed top and bottom or put on like the packing tape side to side.. strapping is an extremely tough material.... best of all very cheap..
I have noticed that the latest flight test designs use a U shaped spar and that they are putting the servos in the spar. Have you tested that design spar?
I'd like to try making the I-beam style, but instead of an I-beam, make it a triangle, since that's the strongest geometric shape, just big enough to accommodate a carbon arrow shaft for the spar inside the triangle. The typical AE Armin wing design with carbon arrow spar has worked really well for me, but I notice a little shimmy sometimes on the videos from the flex under stress. Maybe this design will help.
I have been watching both Flight Test and ExperimentalAirlines videos and have to wonder what both have against composite construction? Seems to me that foamboard in combination with wood/ply/carbonfiber would be stronger and depending on design possibly lighter.
True, composite construction methods can result in very failure resistant model airplane designs, but .... and this is the kicker, both FT and EA are trying to offer very simple construction methods with locally available materials that are low cost. EA offers very simple construction for a basic flying toy, where as FT likes to go a few steps further for appearance using the same materials.
WATCHED with INTEREST... SOMETHING IMPORTANT is getting overlooked though: From a pure Material Science point-of-view... ... some materials have been fabricated for purposes OTHER than "resisting bending stress" :-O CONCRETE is a common material familiar to us all; PAPER_COVERED FOAM is another such material, but for DIFFERENT reasons. Let me explain... Imagine a BEAM of CONCRETE supported at the ends & loaded with a weight in the middle: - the upper-half of the beam will resist COMPRESSION WONDERFULLY (concrete is GOOD at this); but - the lower-half of the beam will SUCK at resisting TENSION, and will FAIL Imagine a BEAM of PAPER-COVERED-FOAM also supported the same way: - the lower-half of the beam will resist TENSION quite nicely (I'll explain WHY shortly); but - the upper-half of the beam will SUCK at resisting COMPRESSION, and will FAIL The REASON the FOAM beam was able to resist in TENSION was because both the FOAM and the PAPER contains STRANDS or FIBERS all BONDED TOGETHER :-O - the PAPER really carries the load here - NOT the foam - BECAUSE of these fibers ! - the hollow-holes-everywhere FOAM offer very little. WHAT DOES THIS MEAN for building SPARS (which EXIST ONLY TO RESIST BENDING STRESS) MEAN? EASY ANSWER: FOAM SUCKS. There is really NO configuration of this material which is going to make using it for a SPAR structure make SENSE :-| ... WHAT TO DO? EASY ANSWER AGAIN: - You're using paper-covered-foam to SAVE MONEY... but you buy CARBON RODS for SPARS??? That makes LITTLE SENSE :-| Instead you need a material made up of LOTS of LOOOONG STRANDS ALL BONDED TIGHTLY TOGETHER, and capable of being glued to PAPER (remember what PAPER is made from?) Hmmmm.... FIBERS.... BONDED.... LIGHT.... CHEAP.... CONNECTED to PAPER... FIBERS.... BONDED.... LIGHT.... CHEAP.... CONNECTED to PAPER... FIBERS.... BONDED.... LIGHT.... CHEAP.... CONNECTED to PAPER... hey... HEY... HOW ABOUT - no this is CRAZY... No - I'll offer it anyway... HOW ABOUT... WOOD ??? I know I know - it's UTTER FOOLISHNESS, right? It's CHEAP, It's EASY to produce It's EASY to work with It BONDS to PAPER effortlessly It's STRANDED and BONDED together at the MOLECULAR LEVEL It's got MORE than sufficient strength for the application at hand (resisting bending stress of a flying plan at 20 mph carrying a wing loading 4 lbs over (say) 60 inches long x 10 inches wide = NOTHING CRAZY, RIGHT ? NOPE. RC MODEL DESIGN DOESN'T SCALE-DOWN FROM FULL-SIZED PLANES GUYS !!! Even common WILL beams are (at scale) STUPIFYINGLY STRONG for their weight, and cheap as HELL. BUILD a FOAM wing with a SQUARE WILLOW SPAR and you literally have EVERYTHING the FLITETEST guys are seeking: - AFFORDABLE - EASY TO WORK WITH - STRONG ENOUGH FOR THE APPLICATION AT HAND I'll say it again... STRONG ENOUGH FOR THE APPLICATION AT HAND In sharp contrast an equivalent CARBON FIBER ROD is actually OVER-DESIGNED and NEEDLESSLY EXPENSIVE :-O C'mon guys... It's perfectly ok to use WOOD with PAPER - gimme a break ! - Mark Vogt | North American Robotics (Drone Engineering & Data Science Startup) :)
I've done the flitetest method for a flying wing with tapered wings and it is very strong. In certain circumstances, the flitetest wing is better, absolutely.
Like your design more. It may add more weight but I like over designs. EA airfoil looks like a real air foil and I am sure it will beat FT design in any aerodynamics test.
I cannot help but marvel the fuselage design is square, but the spar design isn't. What I am thinking is if you made a box spar and filled it with something, you would have all the strength your designs would need. I noticed you like to put carbon fiber tubes as spars in the wings, so the carbon fiber tube is doing most of the work and the only purpose of the foam strips is to fix its location. The foam strips just don't add all that much strength to the wing design, so it is easy to believe using a lot more foam just doesn't do much for the design other than add weight and use up more foam board. What if you couldn't buy the carbon fiber tubes due to cost and availability? That would suggest other options would be needed, as well as tests. In all likelihood that would mean other ideas for spars would need to be explored. Homemade spar tubes, or squares? How about a box spar with a foam-n-can fill? What about a box spar made of foam with balsa wood fill, or some other type of fill? The fiber tape idea is fast, but is it practical, or cost effective? LIkely not compared to other options. Let me make a recommendation that may be what you are looking for. Using foam strips, glue them together without the paper skins with a lightweight urethane glue that foams to save weight. You don't need more than a very thin film on the surface of each foam strip to end up with a FT style box spare of at least three layers of foam board strips. In this case the glue is doing most of the work and the foam is just a space filler. Keep in mind the glue needs to cure under pressure and how much is used can make a difference. Key points are the design is lightweight, provides a generous surface for the wing skins, has no paper weight penalty, can be shaped easily to match the desired curve of the top wing skin, and other modifications can increase the strength many times over. Even a thin strip of balsa that matches the width of the foam board strips can increase the spar resistance to failure many times. I could offer more to ponder, but this is an old video and I'm not sure you will want to test some of what I have offered.
I'm curious what about a foam box (and or a triangle) spar made from one piece of foam board? or even if the shape matters such as having a taper or not. I may have to do some experiments on this.
Not likely. Ed pointed out the more foam, the stronger the foam spar, but he didn't point out strongly what part the glue plays in the overall strength of the foam spar. The glue used can make a huge difference in many ways, to include weight.
The FT Simple Cub I've built and the FT Tutor I'm build now have a "U" shaped foamboard spar. I'm guessing the "U" shape is superior to both the spars that you show in this ~ 6 year old video.
Wow- teaching old dog some new tricks... the tiny amount more weight /versus better perform/and better strength! that's way to go.. 2019- the added piece of test flite.. carbon .. was wonderful /for the speed demon flyers. Us ..slow flyers needs like add 3 inch width + A lot new ways to strengthen the wing /make it last WAY longer= Walmart gots these $0.89... bamboo bar b que scuewers.. like 10 them X 2 feet long.were rubber bands get applied.. add long pieces.. these are slightly larger round and barely fit the 3/16 foam :>) … its perfect. Stops middle snap and keeps rubber bands from dig into the foam ! if add slightly larger tail /rudde r + the 3 inch width to the wing-=u get a sloooow video flyer/trainer. and can handle bigger 3,s battery for longer flight time ! first flight /beginner/ try the super slow wing= make spares and cover top only- cupped both under and over wing= The plane Will Fly Sooo Slow! 5mph.... crazy! hint.. tilt the motor holder down a bit! :>) omg :>)...
I remove the paper only on the wing's upper surface. It bends better without the paper surface inside. You can bend it by rolling it over a table edge IOT get the airfoil curve and then glue it to the spar and trailing edge of the lower surface. I also remove the paper from the top of the EA design spar and where it contacts the upper wing surface. If you use hot glue, it will stick better foam to foam without the paper. If you use Gorilla Glue, pickle where both surfaces meet with a toothpick first before gluing. The GG physically enters the pickled surfaces for better bonding.
Having built a real aircraft spar and wings (Cozy MK4), and building a box shape spar, using unidirectional fiber glass strands, I can tell you the box design is a must. I-Beam spar design is not rigid enough. LongEZ, and many other composite aircraft, have the same construction technique. These are planes that people fly in!
How about using the same amount of foam? Vertical vs stack, same amount... I think it isn't fare to compare them the way you did. I'm confident that vertical would win.
I' built both and each has way more strength than needed for a 40 in without spar and the real test is when it is time to retire the plane and foldup the wing to fit into the trash bin. That's when I realize that the spar has to compress to fold the wing allowing the skins to touch and fold. Almost always had to cut the skin. I've never had a wing failure other than hot glue release connecting to fuse. Combining FT fuses and EA wings produce the most pleasing looking planes.
It's the middle of 2020. IMO Sailor John's comment shows the most foresight: design your wing so it's easy to fold up to fit into the trash bin! That is advice that I can take to heart! I like to use foam ribs myself because it's easier for me to get a smooth curve. Besides, if God can take a rib and make a woman, it seems a few ribs would do wonders for an airplane wing.
I like the general theme of this video, but I have to wonder: if you care enough about a spar's strength to start investigating its material properties this precisely, why look at foamboard and not start with materials that have a better "x property to weight" ratio to begin with? Like various woods or laminates. I mean, we might as well wonder how paper maché would perform as a spar. Still clicked like though.
E A design vertical would be the best. try vertical instead of horizontal. better yet. E A design individually skinned in packing tape before glued in the stack.
I have bought foam planes and I've built a few. I seldom break a wing. More often - especially with purchased planes the tail or nose breaks in two. What to do to make them stronger ?
We disagree! You've done fantastic things for the community and scratch builders everywhere.
Great video and great information :) -Austin
If your wing breaks with a ft style spare you have a much bigger problem
josh
how are you
I am so impressed with what you have done for the foam board plane construction. I admire your spirit of giving and your support of FliteTest. In my mind, you are the reason I built my first plane and will ever be thankful to you.
I really appreciate the more engineering based perspective of this channel.
Ed--Thanks so much for a well thought-out test series! Not only the test methods, but your narration is always precise and shows your intelligence and education IMO.
My personal (and ongoing) experience with DT foamboard is that the bonding of layers of the board with hot glue creates unnatural increases in strength; it's as though the hot glue becomes a structural member, with the foamboard acting as a shear web and forcing the hot glue to maintain its column orientation and strength.
Thanks again and keep up the great work--I know I'm reflecting appreciation of the whole RC flying community here!
I've been experimenting with building these wings using carbon arrow spars and 3D printed ribs and I've had a lot of great success. The nice thing about including ribs is they result in a very nice accurate airfoil every time. I've also created a host of 3D printed parts for the fuselage including motor mounts, wing mounts, bulkheads, etc.
Carbon arrows from Walmart are way cheaper than carbon tubes from a hobby store . I like to walk around stores and look at everything and think about how I could repurpose it
Thanks so much for the video! I used your design to build a 60" wing for a Timber plane that I built. I didn't use any wood spar or support bar and it worked well, my wing was strong. It even held up well in the wind. I just posted a video of my building that plane, if you want to see your experiment in action!
Just getting into it with my grandson. I have built and flown balsa wood planes decades ago all glow with old AM electronics. I have been following Fllight Test for years but I found you and am going to build you r plan first. It looks great to me and should be quite easy to control. Thanks your boss rock.
I was about to post a comment asking if flite test had seen the vid. Then I wisely kept reading to avoid appearing stupid and sure enough there it was. It was a combination of EA and FT that actually got me into model aviation. Keep it up you guys :)
Ed, love the video's. Keep them coming. There are a few FT designs that use a stacked EA spar. The FT Simple Soarer comes to mind. That is by far the best choice of spar for a constant chord, constant thickness, zero sweep wings. Building a spar on edge is used to facilitate ease of construction for taper and sweep. The real benefit in the EA wing build is the efficiency. Build a motor glider that is a cross between a Nube Tube and a Simple Soarer. Then fly it with a 60" wing built EA style then a 60" 3 break FT Style wing. Keep the chord the same for both wings. You will see how slippery the EA wing is compared to the 3 break wing. I would like to see you develop an EA style tapered wing.
Great to see you back expanding our knowledge of DTFB aircraft design and construction. Thank you!!!
Great testing! It was systematically performed and well tested for various factors... Well Done!
Conclusion: Horizontal-stacks of foam provide for more foam/paper mass to take more stress/load than the I-beam, given the mass of I-beam is significantly low.
Future testing: If weight of spars don't account for much in overall wing then stacks of I-beams (vertical stacks) of similar dimensions (l x h x w) to those of horizontal stacks should be constructed and tested. Hypothetically, this method would provide even more strength and can take more load as this construction would counter for more compression stress on top and stretching on the bottom. It would also provide for more direct comparison as to which method is better since the mass is now constant!
ED! Come back!
Just show off builds and do flying videos, enough people will share to large Facebook groups to give questions/ideas for other new videos.
Your my recommendation for every pilot/builder looking for a place to start. 👍
Brilliant analysis. Thanks. Every wing I have folded did so near the fuselage where most of the load is. I have now used a modified FT spar with a 1/32in card stock laminated to the top surface of the spar for 1/3 of the wingspan. It adds very little weight and strengthens the compression zone. I usually don't have a problem at the tension side but add packing tape adjacent to the spar on the bottom inner face, again only for about 1/3 span. Adds strength and keeps weight down. I'm going to try your type spar as well but I might cut out the inner laminates halfway out to reduce weight but keep the full buildup at the high load areas. Thanks again. I enjoy watching and learning from your videos.
It seems like the common weakness of foam board is in compression. perhaps an extra thick layer of hot glue could be applied between the top of spar and the inside surface of the wing to add compression strength.
Also, I've had good results with applying a strip of EPT to the bottom of the wing, with the EPT under tension (bow win up, afix EPT at ends of win, release, smooth EPT down). The simulated crash failure mode of your EA spar stack (breaking the bottom wing skin) would seem to suggest the value of this addition.
Thanks for your Testing, your are a true friend of RC Flite!
Super stuff. A spin on your great discussion is to add tension resistance with a carbon L spar. Take a 8-12 mm square tube, slice the tube such that you have two L shaped carbon spars and use one of the L shaped spars with the Flite Test spar. Works great and better crash resistance. Also, use high expansion spray insulation foam inside the wing, forward of the spare. Again, improved crash resistance. Because, when I crash its high impact....:o)
Hi - I'm a 'Flite Test' spar builder, but I early-on started adding a 2.0 mm - 2.5 mm 'steel reinforcing wire' embedded in the centre of the spar and across the middle third of the wing. I started doing this because many of the wings I build into my planes have dihedral - which in basic engineering terms, is like telling the wing exactly where to fail! :) The wire adds strength but allows some flex, complementing the foam. Also to my way of thinking; if the hold-down elastics or mechanical fixings of the wing to the fuselage are firm enough, this engineering problem is better considered as a half wing acting as a cantilever projecting from a fixed point (the edge of the fuselage or elastic.) Considered this way, the forces acting at the fuselage are an accumulation of distributed bending moments, which all concentrate at the wing root. For me it is about considering at what point the wing 'needs' the extra strength. Anyway - which ever way you approach the problem, the area that fails is the centre of the wing, so that's the bit that needs to be stronger. Maybe there's room for a hybrid wing that uses an EA centre and Flite Test outers? Also I wonder if the 'other option', of laminating a spar vertically from sufficient elements to equal the width of the EA wing spar, would have out-performed the EA spar? I've a sneaky feeling it would have, but concede it would be a nuisance to build it up and get the top and bottom edge flat. Great work though, as always. Alibopo.
flite test outers obviously should increase the strength of an EA beam or even added to the flite test beam just because of the additional mass.. but so would tape...but the carbon rod is 10x greater than both and is easier to install in the EA wing..
nothing beats that except maybe an iron i beam
The Steel Wire, or even Aluminium Mesh, applied to the lower panels of the Dihedral Wing with a layer of Hot Glue smoothed over it, has made my Simple Cub nearly indestructible in high G Maneuvers. 😎
You do this of course, before folding over the top portions of the Wing.
To solve the most obvious issue...
Add more weight - add more Power!
Great video - thanks for taking the time to investigate the pros and cons of both approaches. Interestingly the FT Mini Mighty Arrow uses a tapered C-shaped box spar that accommodates the servo. I'd be interested to understand how this fairs compared to horizontal or vertical foam stacking.
Very interesting, I've been playing with using pink foam from Home Depot as my spars instead of the Dollar Tree Foam. The pink foam appears to be stronger. I do sand the pink foam edge to help the Dollar Tree foam fold over. Basically instead of having 3 pieces of foam I have one. I can drill the end to place a carbon spar into the pink foam, thus giving me even more strength. Just my two cents. Great video Ed!!!
You are correct, the pink Corning's foam board is stiffer and easier to "crack" if you cold roll the 1/4" thick option. If you are using thicker, you cannot shape it by cold rolling without defects and have to shape it in other ways.
great testing Ed man, engineers for life lol. Blooper rolls my man, everyone likes seeing people goof up, add one here and there. Flitetest taught me a lot about RC building, but you think like I do, efficiency is key, and I feel compelled to support your channel. keep up the good work!
Wish you make new video, i think a only people miss u. Ur wing is far better than ft, cheers
Built my foaMWARi crashproof RC airplane thanks to your inspiring and educational videos
Ed, you're incredible. Built lots of your planes. I look forward to your engineering response to the micro/nano (
I'm glad you're back. I really enjoy your videos.
Great video Ed. Thanks for doing the research and sharing. I was curious about your statement that both airfoil shapes were probably equal aerodynamically. So, I put both into Xflr5 (which uses xfoil and is designed for low-Reynolds number analysis). Turns out the EA airfoil is quite a bit better. At Re of 100,000 (roughly 25mph for a 5"-chord wing), the EA airfoil has a peak lift/drag ratio of 42 while the FT airfoil's peak is 25. That's a pretty significant difference and it's almost all due to drag. Even if you figure the wing drag is only 1/4 of the total aircraft drag (rough guess), that's still about a 10-20% overall drag reduction. All else being equal, that translates to a couple extra minutes of flying time on a 10-minute flight (plus, it looks better while doing it).
+Andy Roesch I knew intuitively having big ridges on the LE section of the wing would hurt L/D but almost 2:1 ratio wasn't what I expected. great to hear this, as I've been advising against flite tests wings since they started doing them, there's pretty much no benefit to having the ridges on them.
I too prefer the smooth airfoil as in the Armin wing. The 'facetted' Flitetest method looks a 'little-bit' strange, true. But it works. And works pretty good for a quick-n-simple foam build.
One major advantage it has is its ease of construction for very young hands...
Once I realized that, I became quite impressed!
There is actually strength benefits to having the ridges. Many of the 'features' (folds and bends) you see on car panels serve an engineering role as well as a cosmetic one, they help stiffen and strengthen the panel. Often the rounded shell of a wing is just a skin over an internal structural arrangement. You see this in balsa frame type models. Foam board wings are closer to the monocoque construction. You see this used in most modern cars, where the shell provides much of the strength. The most obvious example of the fold providing strength is the Old Fogey single fold type wing. This is tremendously strong due to the single 'CG' apex 'fold' in the panel. Even more strength is added by the outer wing dihedral elements, which effectively lock the ends of the flat central wing into position. Swings and roundabouts, but those folds do serve a purpose.
I like your design better I’ll be using your design with Carbon spar. Thank you, very informative information
Everyone gets caught up in what type of spar to add to a plane, but they always seem to forget or sometimes ignore the tape spar. The concept of the tape spar is to apply one to two strips of tape along the top and bottom of the wing over the spar. As flex is induced into the wing, the surface tension of the tape helps prevent the foam underneath it from flexing as much as it normally would. On an EPO or EPP foam wing this can substantially stiffen a wing from flexing under heavy loads or high G turns.
With flat foam planes that are coated in packing tape as a sealant or for color, the effect is multiplied by every strip of tape added, especially if there is a lot of overlap. That being said, I still try to add a single layer of tape along the spar line on the inside halves of the wing. If its a lightweight bird, I use normal packing tape. If its something a little larger, I use the extreme tape.
When the tape spar works, it works well. The only real penalty is a tiny bit of extra weight.
The only major caveat to the tape spar (tape in general) is its ability to adhere to the build surface. EPO and EPP foam can flex enough to pop the tape loose and that pretty well negates the benefits of the tape. Depending on the plane, that flex may occur more often than not, so it may be not be a good long term build method. On flat foam that has a paper coating you're left at the mercy of the adhesive used to bond the paper to the foam. With repeated exposure to humidity, hangar rash, general handling, and less than stellar landings the foam and paper usually part ways taking the tape away with it. I have tried removing the paper and applying the tape directly to the foam. For whatever reason, the tape just does not like bare foam. Ive tried several different types of tape and while some stick better than others, none of them bond very well with it. I found that Gorilla tape sticks very well, but at the cost of a huge weight penalty. There is always spray adhesive. The only issue with that is the mess and hassle of trying to apply tape to a surface that is constantly trying to apply itself to you, and the fact that if your not careful the spray will eat your foam. My shop is still a mess from the last time I used it. Everything is coated in a sticky film and that has been well over a year ago. Thanks 3M for making a superior glue. lol.
All of that to say, when you build your plane and your about to start adding your internal spars, consider adding a few extra strips of tape along the spar line from end to end, especially if youre not going to be using tape to pretty up your bird. It can greatly reduce the flex in your build material and it will help reinforce your spar. As evidenced by his experiment, even adding tape to the spar increases its strength.
Very good points! Strength will always cost weight...
Simply add some more power to compensate! 😉
Enjoyed the video Ed, thanks for comparing the two former designs.
glad to see you're back. basement engineering rocks. keep it coming.
VERY interesting video, I wonder what's the impact of even-tamper curved profile of the experimental airline vs the hard edges of the flite test wing on the overall wing strength.
Thanks for sharing
Good to see you again with a super informative video!
I prefer the EA design for the spar, as it is easier to build and add some carbon to it.
I watched this video with interest. Although I don't fly winged aircraft, I flew control line stuff back in the late '60's as a kid and was mentored by some old McDonnell Douglas engineers. They stressed strength to weight highly, and it has influenced everything that I have build since then.
The one test that I wanted to see was your EA 3 ply spar turned on edge like the Flite Test 2-ply spar. My curiosity leads me to think a well adhered laminate would bring more of the I-beam strength to the study.
Two thoughts, how are you adhering the foam layers, and how about cutting the spar after the glue has dried. I'd like to see if the paper layers plus the adhesive are stronger in the vertical application.
My hobby has been woodworking for the last 30+ years, and it's usually true that if a structural support is wider than it is tall it is almost always stronger in the vertical orientation.
The only issue I am concerned about is finding a glueing technique that is light enough that yields a good bond that isn't brittle.
The one product that I can think of right now is Titebond makes a liquid hide glue that is used in wood veneering that is tough, thin, and has a long "open" time to give you time to align the poster-board while both bonding sides are still wet enough to flow to eliminate most of the air.
I think it might be worth a try.
Hey, if it intrigues you perhaps one day you might try it. You already have some much data collected, it might be worth that addition.
I like to hear your thoughts. You have certainly provided a thoughtful presentation.
Thanks !
simple engineering... the greater the height of the ibeam center the greater the strength..in principle..so id assume so..add tape and even more so
Your curiosity has some good points and when it comes to foam board glue, Gorilla glue that foams is hard to beat. My acid test for foam board glues is the butt joint. It is one of the weakest joints we use in the hobby and can make or break the usefulness of a glue real fast. There are all kinds of disciples dedicated to a specific glue and they make videos to give praise to their choice, but I have noticed they tend to avoid showing the butt joint test, or how much glue they used. How long that glue remains useful is another detail few are concerned with since most of their models are flown for a season, or two and abandon for a new project. As to the foam board, remove the paper skins first and save a lot of weight. The glue used does most of the work since the foam is just a space filler. Any coatings applied help the foam survive longer and have to be lightweight, or the construction has to be more than foam and thin balsa, other materials, and plywood.
Just discovered your channel. Loving your work, loving your attitude. Liked, subscribed and commented. Keep it up.
Seems pretty clear: Overall performance - lower weight with better yield goes to FT design. Which is easier to build is rather subjective - I'd go with either. But, how many wings fail mid-span on an even spar? None for me. Wing joints, etc, are where the issue typically falls, and the entire chord design is crucial, including spars, etc. Thanks for the analysis.
What Ed didn't talk about all that much is how the carbon fiber tube does the lion's share of the wing support to prevent failure and the only thing the foam does is trap it in place. A significant design detail that wasn't point out well.
you channel is very educative... thanks a lot.... you are the best
I like that you tested this different forms of wing spars and I have bad experience with the flitetest spar made out of 6mm depron (had to put carbon in an FTCruiser as the wings were flopping around). But the efficiency of stress vs weight should be way better with the flitetest design. And you applied the extreme packing tape on the FT + versions on the wrong sides of the spar.
The thought of an I-Beam is that the Compression and Tension only gets taken by the outer foils which in our case is the wing surface. Packing tape in itself can only take tension forces. Because of that the extreme packing tape should applied horizontally on the outer surfaces of the spar or if possible even on the wing surfaces as they are further from the mid of the spar and therefore can take more tension. If you fly scale and never do negative g manovers it would be enough to put the packing tape on the lower side of the wing. As it will only add weight if you use it on top and not take any compression.
If one needs more strengh then the flitetest spar method allows it would probably best to put another spar in another region of the wing, trying to use more surface area of the wing to put tension and compression in. Or make hybrid of both designs using only flitetest spar in middle but adding a strip of foam on each surface as extra layer to take more compression forces.
Nonetheless like you said your method is the easier one to build and looks way better and in reference of simple build designs which can take higher forces, yours will win.
Also I may be wrong and the compressibility of the foam may already begin to matter, as I learned this stuff with with metals and not foam and you have way more experience with that. At this point they type of foam and it's orientation of use could actually already matter as the same foam can take way different forces depending of direction of use (depron is really floppy in one direction and way more stiff in the other)
I hope I gave some good ideas, keep going with this channel. I really like it.
Now that was in depth, I have wondered for a while how much stiffness the carbon spar gives me, (a whole lot it turns out!) now I wonder about vertical plywood, aluminum angle, and carbon strip.. another video?
Very nice, thanks for explain and presentations. Appreciate it 👍
Thanks for all your great videos. Keep it up !
Great video as always. I think the FT "faceted" wing design has an extra feature that was missed. When making the wing, I always glue the facets in one glue operation and then the leading edge and spar in a second operation. I do that because its way more complicated to glue so many joints at once without screwing something up. It always surprised me how strong just the faceted top wing section was without the spar. I don't think a second video is required, but i'm curious what the strength difference is between the curved EA top wing plate and the faceted/glued FT top wing plate. I don't use much glue in the faceted joint but i'm sure it helps with the overall strength.
Keep up the good work!
thank you for this really detailed and professional video, very helpful indeed. Just wanted to ask you, is foam board better or depron. thank you again.
I recommend wooden spar because if you try to be as cheap and quick as possible, hard wood stick is the answer.
hard wood is more expensive than foam board, and harder to come by for most people. And since you're already building the surfaces with it, you already have it (foam board). Foam is typically lighter as well.
You could use both versions and have an even stronger albeit heavier wing ...ea style spar for a forward spar and a ft half spar as a rear spar...depending on your wing size of course
Hola desde España. He aprendido mucho de tus videos yo también me dedico a este fabuloso mundo del aereomodelismo. Darte las gracias en primer lugar por todo lo q haces por este canal.... Me gustaría por favor q me dijeras donde puedo comprar el material q tu unas en tus proyectos y sie podruas pasar las medidas del phanto q tienes. Muchas gracias de nuevo.....
as of 2019 the last two FlightTest kits I built ( Explorer, Simple Soarer ) use horizontal spar wing
Great informative video thank you, what about a triangular foamboard spar? it might not form the aerofoil as nice as the Flat stack EA spar but I think the strength would be better.
Im new to making rc planes and drones, but i was just wondering, imagine battery wasnt a issue, would the gps of the rc plane/drone have signal world wide? Even 9000km out? Or does signal have a limit?
A gps doesn't add range. The vtx and rc link would be the limit. All a gps does is add things like return to home, direction to home,
I've been experimenting with various sizes of 36" long Balsa sticks ranging from 3/16" x 3/4" up to 3/8" x 1" with beveled upper edges and a bead of Foam-Safe CA glue on the top and bottom. Once the glue impregnates the wood a bit and dries, it creates a super stiff layer. It's surprisingly strong, if a little heavier than a DTFB spar.
I'd love to see a strength comparison of that against an EA style spar.
I definitely need to remove the paper inside mine though. Getting a smooth curve is nearly impossible otherwise.
Very informative. Personally, I think your design is better simply because it is easier to construct and because it is stronger. Also, your wings are a lot more compact and sleek compared to some of Flite Test's designs, which means there's probably less drag on your planes. Can't say for sure without wind tunnel tests or scientific trials though, but that's what my intuition tells me.
I have found the strength of the wing doesn't depends alot on the spar. it's the fold on the foam.
But all in all, wonderful video Ed.. hope to see many more.
The primary thing that prevents wing failure is the carbon fiber spar.
Mr. EA. You win. Very nice.
+Mr. Sparkle And I also meant to say....both designs are superb but have different applications as you said. I wonder how a 'filled I-beam' would perform....
hey Ed, do you have the ability to do an experiment to show which airfoil has better lift. Or do you already know?
If lift is your only concern, then obviously a study of airfoils used in cargo and bomber designs answers the question.
Hi, I have been playing with incorporating the Plastic strapping you get round big packages, bricks etc into my spars with some good results.
Hot glue however isn't compatible with these materials and so I have been using gorilla glue.
It adds a lot of strength and little weight.
Ed - Have you considered an alternate method of covering using craft paper & glue? Instead of packing tape on the outside, use brown craft paper saturated with white glue diluted 50% with water. I'm curious what the weight, tension, compression and crush load differences would be using this method over the FT method of leaving the paper on the foam board and your method of using packing tape covering.
The idea of this video was not terrible but It wasn't an apples to apples comparison.
What about a triangular prism spar? (never built an rc plane in my life so there may be complications that I am not aware of)
Some designs use the triangle spar, but it does use more foam strips unless you only use two and use the wing inner surface to finish the triangle. Other designs use a modified triangle by inserting a strip of foam in a box, giving two triangles side-by-side. The basic feature most are trying to make use of is how a triangle will resist twisting, or warping until the material it is made of, or glue bond fails.
The EA design is good but if you turned the spar 90 degrees so the glue edge was up and down instead of front and back that would I'm sure make a tougher design, Thanks Ed for yet another great video. Now go and do some flying.
What keeps the upper surface from pulling the lower surface trailing edge upward?
Thank you very much for this video!
ive been making my spars using a pallet strapping sandwich.. strap/foam/strap.. this gives a very strong spar...the straps can be fixed on the spars or on the outside of the wing..
+John Reap RC Planes the straps can be fixed top and bottom or put on like the packing tape side to side.. strapping is an extremely tough material.... best of all very cheap..
hope to see a dlg EA scratch build!
I have noticed that the latest flight test designs use a U shaped spar and that they are putting the servos in the spar. Have you tested that design spar?
I'd like to try making the I-beam style, but instead of an I-beam, make it a triangle, since that's the strongest geometric shape, just big enough to accommodate a carbon arrow shaft for the spar inside the triangle. The typical AE Armin wing design with carbon arrow spar has worked really well for me, but I notice a little shimmy sometimes on the videos from the flex under stress. Maybe this design will help.
I would have liked to see a combination of both ;)
Thanks for doing the tests and this video...
Great work ,thanks!
I have been watching both Flight Test and ExperimentalAirlines videos and have to wonder what both have against composite construction? Seems to me that foamboard in combination with wood/ply/carbonfiber would be stronger and depending on design possibly lighter.
True, composite construction methods can result in very failure resistant model airplane designs, but .... and this is the kicker, both FT and EA are trying to offer very simple construction methods with locally available materials that are low cost. EA offers very simple construction for a basic flying toy, where as FT likes to go a few steps further for appearance using the same materials.
For taper wing I prefer FliteTest type.
WATCHED with INTEREST...
SOMETHING IMPORTANT is getting overlooked though:
From a pure Material Science point-of-view...
... some materials have been fabricated for purposes OTHER than "resisting bending stress" :-O
CONCRETE is a common material familiar to us all;
PAPER_COVERED FOAM is another such material, but for DIFFERENT reasons.
Let me explain...
Imagine a BEAM of CONCRETE supported at the ends & loaded with a weight in the middle:
- the upper-half of the beam will resist COMPRESSION WONDERFULLY (concrete is GOOD at this); but
- the lower-half of the beam will SUCK at resisting TENSION, and will FAIL
Imagine a BEAM of PAPER-COVERED-FOAM also supported the same way:
- the lower-half of the beam will resist TENSION quite nicely (I'll explain WHY shortly); but
- the upper-half of the beam will SUCK at resisting COMPRESSION, and will FAIL
The REASON the FOAM beam was able to resist in TENSION was because both the FOAM and the PAPER contains STRANDS or FIBERS all BONDED TOGETHER :-O
- the PAPER really carries the load here - NOT the foam - BECAUSE of these fibers !
- the hollow-holes-everywhere FOAM offer very little.
WHAT DOES THIS MEAN for building SPARS (which EXIST ONLY TO RESIST BENDING STRESS) MEAN?
EASY ANSWER:
FOAM SUCKS. There is really NO configuration of this material which is going to make using it for a SPAR structure make SENSE :-| ...
WHAT TO DO?
EASY ANSWER AGAIN:
- You're using paper-covered-foam to SAVE MONEY... but you buy CARBON RODS for SPARS???
That makes LITTLE SENSE :-|
Instead you need a material made up of LOTS of LOOOONG STRANDS ALL BONDED TIGHTLY TOGETHER, and capable of being glued to PAPER (remember what PAPER is made from?)
Hmmmm....
FIBERS.... BONDED.... LIGHT.... CHEAP.... CONNECTED to PAPER...
FIBERS.... BONDED.... LIGHT.... CHEAP.... CONNECTED to PAPER...
FIBERS.... BONDED.... LIGHT.... CHEAP.... CONNECTED to PAPER...
hey...
HEY...
HOW ABOUT - no this is CRAZY...
No - I'll offer it anyway...
HOW ABOUT... WOOD ???
I know I know - it's UTTER FOOLISHNESS, right?
It's CHEAP,
It's EASY to produce
It's EASY to work with
It BONDS to PAPER effortlessly
It's STRANDED and BONDED together at the MOLECULAR LEVEL
It's got MORE than sufficient strength for the application at hand (resisting bending stress of a flying plan at 20 mph carrying a wing loading 4 lbs over (say) 60 inches long x 10 inches wide = NOTHING
CRAZY, RIGHT ?
NOPE.
RC MODEL DESIGN DOESN'T SCALE-DOWN FROM FULL-SIZED PLANES GUYS !!!
Even common WILL beams are (at scale) STUPIFYINGLY STRONG for their weight, and cheap as HELL.
BUILD a FOAM wing with a SQUARE WILLOW SPAR and you literally have EVERYTHING the FLITETEST guys are seeking:
- AFFORDABLE
- EASY TO WORK WITH
- STRONG ENOUGH FOR THE APPLICATION AT HAND
I'll say it again...
STRONG ENOUGH FOR THE APPLICATION AT HAND
In sharp contrast an equivalent CARBON FIBER ROD is actually OVER-DESIGNED and NEEDLESSLY EXPENSIVE :-O
C'mon guys... It's perfectly ok to use WOOD with PAPER - gimme a break !
- Mark Vogt | North American Robotics (Drone Engineering & Data Science Startup) :)
I've done the flitetest method for a flying wing with tapered wings and it is very strong. In certain circumstances, the flitetest wing is better, absolutely.
Hey Ryan (YBR) did you buy that color printer yet , by the way , nice mod , I've downladed it and it was great .
Subscribed and bookmarked thank you!
Like your design more. It may add more weight but I like over designs. EA airfoil looks like a real air foil and I am sure it will beat FT design in any aerodynamics test.
I cannot help but marvel the fuselage design is square, but the spar design isn't. What I am thinking is if you made a box spar and filled it with something, you would have all the strength your designs would need. I noticed you like to put carbon fiber tubes as spars in the wings, so the carbon fiber tube is doing most of the work and the only purpose of the foam strips is to fix its location. The foam strips just don't add all that much strength to the wing design, so it is easy to believe using a lot more foam just doesn't do much for the design other than add weight and use up more foam board. What if you couldn't buy the carbon fiber tubes due to cost and availability? That would suggest other options would be needed, as well as tests. In all likelihood that would mean other ideas for spars would need to be explored. Homemade spar tubes, or squares? How about a box spar with a foam-n-can fill? What about a box spar made of foam with balsa wood fill, or some other type of fill? The fiber tape idea is fast, but is it practical, or cost effective? LIkely not compared to other options. Let me make a recommendation that may be what you are looking for. Using foam strips, glue them together without the paper skins with a lightweight urethane glue that foams to save weight. You don't need more than a very thin film on the surface of each foam strip to end up with a FT style box spare of at least three layers of foam board strips. In this case the glue is doing most of the work and the foam is just a space filler. Keep in mind the glue needs to cure under pressure and how much is used can make a difference. Key points are the design is lightweight, provides a generous surface for the wing skins, has no paper weight penalty, can be shaped easily to match the desired curve of the top wing skin, and other modifications can increase the strength many times over. Even a thin strip of balsa that matches the width of the foam board strips can increase the spar resistance to failure many times. I could offer more to ponder, but this is an old video and I'm not sure you will want to test some of what I have offered.
Жалко что нет перевода, интересно бы послушать и понять рассуждения и выводы.
Would you mind to do a comparison video between the turbulent FT wing and your smooth wing ?
He hasn't done anything in over 3 years... 😞
@@CarminesRCTipsandTricks Really ! Where is Ed ?
Nobody seems to know...
EA all the way and better looking wing too
Any difference in flight characteristics? Particularly, the curve vs bend in airfoil?
really nice video. thanks for sharing
also use ribs in foam as well very strong
I'm curious what about a foam box (and or a triangle) spar made from one piece of foam board? or even if the shape matters such as having a taper or not. I may have to do some experiments on this.
what if you just make a thin EA version, so that it weighs less but is stronger than the vertical one. Is this possible?
Not likely. Ed pointed out the more foam, the stronger the foam spar, but he didn't point out strongly what part the glue plays in the overall strength of the foam spar. The glue used can make a huge difference in many ways, to include weight.
The FT Simple Cub I've built and the FT Tutor I'm build now have a "U" shaped foamboard spar. I'm guessing the "U" shape is superior to both the spars that you show in this ~ 6 year old video.
Outstanding!
Sir for 5 or 6 kg weight which material will be required.???
Hello. Have you tried an actual "I" beam? Aka a combination of both thereby taking advantage of strength and weight?
there are colored foamboard, so you can make a nicer model using transparent packing tape, or you can also paint the white foamboard.
Wow- teaching old dog some new tricks... the tiny amount more weight /versus better perform/and better strength! that's way to go.. 2019- the added piece of test flite.. carbon .. was wonderful /for the speed demon flyers. Us ..slow flyers needs like add 3 inch width + A lot new ways to strengthen the wing /make it last WAY longer= Walmart gots these $0.89... bamboo bar b que scuewers.. like 10 them X 2 feet long.were rubber bands get applied.. add long pieces.. these are slightly larger round and barely fit the 3/16 foam :>) … its perfect. Stops middle snap and keeps rubber bands from dig into the foam ! if add slightly larger tail /rudde r + the 3 inch width to the wing-=u get a sloooow video flyer/trainer. and can handle bigger 3,s battery for longer flight time ! first flight /beginner/ try the super slow wing= make spares and cover top only- cupped both under and over wing= The plane Will Fly Sooo Slow! 5mph.... crazy! hint.. tilt the motor holder down a bit! :>) omg :>)...
When you build the wing do you remove the paper on the inside of the wing ?
He doesn't seem to answer anyone anymore... 😐
But yes he does. Take a look at the Video Series he made before this, on his Arman Wing.
I remove the paper only on the wing's upper surface. It bends better without the paper surface inside. You can bend it by rolling it over a table edge IOT get the airfoil curve and then glue it to the spar and trailing edge of the lower surface. I also remove the paper from the top of the EA design spar and where it contacts the upper wing surface. If you use hot glue, it will stick better foam to foam without the paper. If you use Gorilla Glue, pickle where both surfaces meet with a toothpick first before gluing. The GG physically enters the pickled surfaces for better bonding.
I'm confused... FT spars don't look like that, they have a "C" shape. Is that something they've changed since this video was published?
Спасибо за видео 👍
why not a vertical stack with a horizontal topper?
Having built a real aircraft spar and wings (Cozy MK4), and building a box shape spar, using unidirectional fiber glass strands, I can tell you the box design is a must.
I-Beam spar design is not rigid enough. LongEZ, and many other composite aircraft, have the same construction technique.
These are planes that people fly in!
Stack and Vertical.. (with narrower stacks) attach them together :)
+dege13 ....That's how I would do it. Vertically oriented making a wider stack.
How about using the same amount of foam? Vertical vs stack, same amount... I think it isn't fare to compare them the way you did. I'm confident that vertical would win.
iS COROPLASTIC 4MM BETTER FOR A WING DESIGHN?
what size of foam board should be used?
I' built both and each has way more strength than needed for a 40 in without spar and the real test is when it is time to retire the plane and foldup the wing to fit into the trash bin. That's when I realize that the spar has to compress to fold the wing allowing the skins to touch and fold. Almost always had to cut the skin. I've never had a wing failure other than hot glue release connecting to fuse. Combining FT fuses and EA wings produce the most pleasing looking planes.
It's the middle of 2020. IMO Sailor John's comment shows the most foresight: design your wing so it's easy to fold up to fit into the trash bin! That is advice that I can take to heart!
I like to use foam ribs myself because it's easier for me to get a smooth curve. Besides, if God can take a rib and make a woman, it seems a few ribs would do wonders for an airplane wing.
I like the general theme of this video, but I have to wonder: if you care enough about a spar's strength to start investigating its material properties this precisely, why look at foamboard and not start with materials that have a better "x property to weight" ratio to begin with? Like various woods or laminates. I mean, we might as well wonder how paper maché would perform as a spar. Still clicked like though.
E A design vertical would be the best. try vertical instead of horizontal. better yet. E A design individually skinned in packing tape before glued in the stack.
I have bought foam planes and I've built a few. I seldom break a wing. More often - especially with purchased planes the tail or nose breaks in two.
What to do to make them stronger ?
I glue popsicle sticks to the inside of the tail.