It's remarkable to see just how consistent the entire skin of the aircraft looks, the machined tooling has paid off so well. Most aircraft of this scale have noticeable waves and irregularities just all over the surface
I didn't see any mention that the long torque tubes through the wings, at the cabin, don't pivot at the tube? Hard to explain, and I don't have the correct vocabulary to properly describe, but watch closely at around the 6:00 mark. The inboard bell cranks are anchored on one of the ears?! Is it very weird that the inboard ends of the torque tubes move up and down in space?
Where’s the elevator trim? Or did you cover that already? ctrl sfc balance…what a concept.. At least nobody in your team cited “actuator stiffness” as a justification to forego balancing the ctrl sfc.😂 never mind, I haven’t watched it all the way when I asked about trim, wah wah…
Nice, heim joints, bell cranks and torque tubes, with not a whole lot of translation, so backlash should be minimal. You might want to also mention that the control surface weights, by projecting up into the airstream forward of the hinge point, also help manage control forces at higher airspeeds. The split rudder works VERY effectively as a speed brake, I use them this way all the time on my Cozy. I am curious what you're using as a rudder return spring - it looks like you're using push-pull cables to actuate each rudder, but I don't see space inside the rudder for a spring assembly - is it at the pedal end? If so, how do you plan to prevent buckling of the cable in push near the pedals if there is resistance at the rudder end? You'd need a decent sized spring to overcome the friction of a push/pull cable that long. Do you engage the brakes master cylinders only after you get full rudder pedal travel? How do you ensure you can land with the rudders deployed, but without the brakes deployed? (I'm assuming the nosewheel is full castering?) Lastly, I didn't see the roll servo, I'm curious as to where it's going to end up - it looks the only practicable place is behind the seats?
- How I heard it, the rudders are independent - with only a pull cable (spring return to centre) - ??, is the rudder deviation only from centre to full lateral deflection (left or right) ? - OR having no centre stop, the lee side rudder (low pressure) just follows the pressure side (half) to full deflection under spring action? - using the airbrakes on a steep straight-in approach sounds kind of similar to balancing regular toebrakes for yaw control, from the sound of it.. hmmm... Some high performance lightweight RC craft also only use a (single acting) pull cable (kevlar thread/kite-line often used) for tail unit control, the tension is maintained by spring tension as is full tension deflection - balanced by servo force - (spring-pull rudder and elevator - no tensioning problems or slop can intrude)
I think they're making a mistake with the split rudders in the way they have them designed. They really need to follow each other at least somewhat past centerline for the first third of their travel before splitting, with canard aircraft a little misalignment doesn't come with a drag penalty but it certainly will with a split rudder, and especially so with conventional tractor configuration slipstream hitting the vertical. There will only be a single speed and throttle setting in which the two rudders are streamlined and together, the rest of the time one or the other will be split, meaning you'll always have a small amount of airbrake deployed. The rudder pedals should also be interconnected in their movement with airbrake function as a separate lever to actuate that simply moves two pulleys to shorten the rudder cables. This would allow standard toe brakes to be used instead of pushing the pedals to the floor and forcing the airbrakes open in order to make the toe brakes work, or having to use the dreaded piper style hand brake. You may not always want to use brakes with the airbrake deployed for whatever reason, and not being able to put any pressure on the rudder pedals during flight to avoid deploying the airbrake is going to suck.
One of the potential problems i have concern about is the spin recovery characteristics. The split rudder and location of the stabizer and elevater seem to be in positional relation ship to the rudder to cause "blanking" of the half rudder because the opposite half stays in neutral
Always a great presentation… Tungsten makes an interesting choice. Density, and doesn’t corrode at ordinary temperatures of aircraft operation…. And not soft like lead. There is a recent AD for these elevator balance weights on a popular airplane because the weight was cast in a tube… and corrosion formed between the lead and the tube…. The corrosion forces expansion and the weight tries to fall apart. The problem took 20+ years to appear… but, once started the rate of oxidation increases, exacerbating the problem… Go DarkAero! 😃
Is there an expected loss in rudder authority with your design compared to conventional designs, since only half of the rudder deflects with say a right rudder input. Wouldn't the fact the left half of the rudder remains within the line of the airflow "block" some of the airflow from adhering to the interior side of the deflecting right rudder and therefore reduce effectiveness?
It looks like it shifts the air flow point of indecision on the leading edge so that more air will flow over the clean side and move with higher speed giving more lift. Will it be _efficient_ and forceful enough for fighting *repeating* turbulent air gust rapid wing rises or more importantly immediate effective and powerful spin recovery? Imagine an inadvertent spin at aft C.O.G. with those pretty, narrow wings.
TECHICAL PTS ONLY Your rudder is just skin. It should've ribs. Otherwise, it gonna collapse under aero load, locking its hinge, making it catastrophic. Too many linkages providing failure pts. Trim tabs is another set of failure points...Instead give trim tabs on stick like RC model Longer control horns proportionally minimize backlash.
What about ICING inside the split rudder design? Will you test the push force overcoming ice adhesion? Another option is adding heat for safety. Love the concept, but Ice and Breaking concern me.
We designed split rudders into the Lynx suborbital space plane we were developing at XCOR for similar reasons- it allows speed brake function and also was much simpler to actuate given their locations at the wingtips. We were also able to include a slight preload against the stop to provide greater resistance to flutter, important in a supersonic aircraft.
Interesting rudder/spead brake. One thing I wonder about is propeller slipstream. On the Rutan canard airplanes the vertical stabs and rudders are outside the spiraling slipstream. On the DarkAero, it will be in the slipstream. I'll be interested to see how you deal with that, as well as rudder trim. My understand (which could very well be wrong) is that on the Rutan canards, the rudders on the winglets is more about creating drag rather than lift. Same goes with split style of flaps on other airplanes. I'm not an aeronautical engineer so I might be all wet... I'd like to see your split rudder act more conventionally with the rudder pedals and have a separate mechanism to split them. Kind of like the A-10 ailerons do. Hmmm... Or.... Leave the rudder conventional an put the speed brakes on the ailerons just like the A-10's! Keep up the good work.
I agree with you. Rutan design is based on drag. In conventional control surfaces it’s the back side of the control surface that moves the airframe. It’s a wing you might say creating lift. Left rudder input means the right side of the vertical fin and right side skin of the rudder making a positive airfoil moving the tail in the left direction. I question if this will work well. I’m not an engineer but have been designing and building model aircraft all of my life for 50 years or so. Have studied design for decades. I guess we will know one day. Great project!!!
Very interesting rudder design, really clever double identity for a rudder. However, even though I don't see this bird doing dive bombing, the dive bombers in WWII also had an air brake, which didn't work until they poked it full of holes. Before the holes, the dive flaps ripped themselves off the airplane in some dives. There's going to be quite a vacuum in between your rudder panels. They're also small, unlike the surfaces of a dive brake, so making them work without unexpected consequences should be easy. Holes near the very front of the control surface should do, and won't interfere with the forward flight aerodynamics of the surface, but it will do the pilot and structure a favor. They can be made as decorative as they are functional.
The Long EZ 'rudders' are somewhat required to be airbrakes, since they use a different principle to normal rudders to yaw the plane. Normal rudders apply lateral lift to the tail to pivot about the center of gravity. Since the Long EZ rudders are more to the sides rather than behind the CoG, the force required to pivot around the CoG is almost straight backward, ie, drag. And they need to be differential so that their is a net torque. If the EZ rudders were set up to act in unison, in the same direction, you would find that it would barely yaw.
The LongEZ and Cozy both place the rudder aft of the Center of Gravity. Rudder deflection yaws the aircraft in the conventional sense. Yaw control also benefits from some increased drag located far outboard. But the drag increment is minuscule compared to lift increment from a deflected flap. This is self evident in all flapped airfoil wind tunnel measurements.
You might want to consider a lockout for the split rudder for takeoff and climb. Canard flyers of various makes have had issues during engine outs of panic stomping on both rudder pedals, exacerbating the emergency. This is of course, alleviated with training. Also, a lockout would keep the passenger from inadvertently inputting while shifting their position, ect.
The ability to flip a switch to convert the rudder(s) into a single control surface would inherently be safer. (If this function is actually desired) Failures to the pins/flanges shouldn't lead to any particular dangers.
I agree. I imagine there's a small aerodynamic penalty to using split rudders. I'm pretty sure the split rudder has more drag in use than a conventional rudder. Having a speed brake likely makes any loses worth it.
@@fdelacou- It could replace flaps for giving drag while reducing altitude without gaining airspeed. Won’t add lift for slower takeoff and landing speeds though.
@@fdelacou NO. Flaps increase lift and drag, important to minimize and bleed KE during landing. Lift is critical for this. Flap extension is typically not allowed at high speeds due to high loading they can create.
I used to fly the SAAB 340 and it had the most amazing redundant elevator system. Basically the left control column controlled the left half of the elevator and the right control column controlled the right half of the elevator. Normally they'd work together as one unit as there was a friction and mechanical plate that meant that if one side moved the other side moved as well. But crucially if part of the system jammed you could overpower the linkage between the two sides and still be able to operate at least half of the elevator. I always thought this was an amazing way to provide redundancy.
I never tried the split rudder although I thought a lot about it. I have flown canard aircraft so I understand the speed brake part of it. Good job! Also it looks like you have some differential in the ailerons. Very good! Something I did a lot was flattening and widening the aileron counterweights so they tuck up inside the wing tips only when the aileron deflects down but the weight enters the wind stream when the aileron deflects up. This adds some parasite drag to the to the up aileron side of the aircraft thus reducing the amount of rudder required to maintain coordinated flight. It's good to see some young people that know how to think out good design. Keep it going and be careful. Thanks for the videos!
I am predicting the rudder will be changed after flight tests. It would be more sensible to let the split rudder stay together as it moves left and right and only opens up when a speed brake is actually required. Easy enough to do with a mixer. On an aircraft designed for utmost efficiency, getting a drag brake opening every time you use the rudder makes no sense.
_Trim tabs. Trim tabs? Trim tabs!_ You use uber-expensive _tungsten_ in preference to super-cheap lead, in a presumption to eek out a tiny advantage in drag (in flight regimes whereof drag is sometimes desired anyway), when at the same time you use trim tabs which _always_ introduce weight, complexity, and/or (unnecessary) parasitic drag in _all_ flight regimes? It´s just as well that you can distract the consumer with that cool split rudder, as then there is less chance you need rationalize a technology that even a century ago had multiple alternate engineering solutions and workarounds.
I didn’t hear anything about designing out flutter? This is of great technical interest to me. It is also the practical speed limit for many airframes, assuming they have lots of hp like this one. Would especially be applicable to high powered turbo normalized aircraft
+1 for rudder trim! Not always needed… but always appreciated! Really nice for those long climbs to altitude… and extra speed during the descent. Kinda like a yaw damper for the auto-pilot too… not a requirement, but really nice to have in the bumps… Don’t fly sideways! 😃
Ngl, I love everything about the split rudder aside from the control scheme you've selected. Conventional rudder pedals (push one and other moves opposite) with a seperate speed brake lever similar to what youd see on a jet's throttle quadrant would be much better as far as avoiding inadvertent speed brake application and making the transition from other aircraft more seamless.
As always the ailerons will create some adverse yaw that will have to be counteracted by rudder. Unfortunately the split rudder is going to cause a lot of drag during routine turning.
I like the split rudder as an air brake. But I hope you have considered how the airplane will react in flight with only half of the surface deflecting? With this, you are splitting the airflow, creating a void of air forming low pressure pocket behind the airplane. This means any time you use the rudder (usually at low speed TO or landing) you are adding a lot of drag, which could decelerate the plane at a critical moment. Another negative aspect I foresee is that while one side is deflecting, the other side is still in place, acting as a vertical stabiliser. I believe this will negate a lot of the effective yaw control and may require a lot more deflection to get an adequate response. Just my thoughts. Would love to see how you guys have tested this concept.
The drag force is reduced at lower speeds, and it's likely that the aerodynamic force when using normal rudder input will pull the opposite rudder along (unless the surfaces are blocked from moving across the center point).
The independent rudders are great. A very safe way to operate a speed brake without forgetting the boards are out. Yes, this happens, even with highly trained and experienced airline pilots they forget to stow the speed brakes.
Really proud of you guys, I have been following you guys for 3 YEARS. If I get a visa to the US, I must come and visit you guys. The consistency is amazing.
It is staggeringly banal to spend so much viewer time 'explaining' how conventional three axis controls work - do you really think that anybody needs to be 'educated' like this ? Explaining how yours wheels work might be about as informative .. The 'split' rudder is not novel either - my "Opal" design from 1975 and published drawings show this and explain the glide path control function (familiar to all glider pilots ) Grumman Intruder, B2 bomber and lots of others use the same chordwise split for drag modulation -you lose a LOT of rudder power by not moving BOTH halves in assymetric deflection as you seem to indicate (ie the yaw function) and I think that your vertical tail is already slightly undersized especially in view of the long nose and high power installed . Your design follows the well worn path of overpowered 'boy's toys' in the vein of the Polen special, Brokaw, Sx300 and similar types of 'pseudo' WW2 fighters -- but lack the purpose driven design criteria of a real period fighter . Once you are reasonably high there is no apparent 'speed' as such like a race car or motorbike provides and 'beat ups' or dangerous low flying hardly amount to a design justification for 'thrills' . If point to point speed in real transport is the idea then for private citizens the real measure ought to be DOOR to DOOR which is the relevant measure and is hobbled by the logistics of getting to and from your 'friendly local long hard surfaced runwayed, hangar equipped, fuel on tap etc '"Local" airport .... usually miles from where you live or need to go on 'arrival' . It would be much better for you guys to use your resources and obvious engineering talents on something that addresses this USEFUL goal and might contribute something worthwhile to society and aviation in a manner that fosters public acceptance and even enthusiasm for general aviation (indulgences that only usually appear as accident reports in the public eye or show aviation as an adolescent extravagance in a cash strapped economy with real problems that aviation might better address ... look into Advanced air mobility, roadability and similar googleable terms for 'inspiration'.
You guys are awesome! Everything is very well thought out. The split rudder is a great feature. Using it to slow the plane down is very nice. I have to ask, in turns, does the other half, the straight half, hinder the turning ability of the turning half, enough to notice? Do the halves open up enough to maybe offset any drag? Again, great job! I hope to have the money to buy one of your airCRAFT one day! Take care
It looks like it's castering (ruclips.net/video/H8Ugh2fzd0I/видео.html) but this still involves controlling the braking mechanism. I didn't look carefully for past videos on this.
Great video, as always. In addition to clearly explaining the basic operation of your control system, I especially liked how you quickly touched on the considerations that went into the design; such as goals to minimize friction, backlash, compliance, and weight while also ensuring easy of service.
You should reconsider the current rudder actuation. As @aaronhammond7297 mentioned in a comment a few days ago the Long EZ 'rudders' are somewhat required to be airbrakes because the force required to pivot around the CoG is almost straight backward, ie, drag. Which is not true for your design. Every time one will actuate the rudder it seems that it will also create some serious drag, due to rudder's size. Considering that you designed the plane for speed, that's a major oversight. Sometimes being different is not being better. You can keep the split rudder design, but the halves should move together, unless the brake is actually wanted and applied intentionally some other way.
How bad is the performance loss during initial climb when using a lot of right rudder? It seems like you’d be trying to climb with the speed break basically partially deployed if you have a consistent rudder input in
Very cool, congrats on the innovative design! I'm still looking forward to HS taxi testing/ TO roll testing. I looked at the similarities/differences between the DarkAero and a TBM for TO roll (for P-factor). They are somewhat (loosely) the same. The TBM has a large rudder, and needs it to hold center line on TO. It will be interesting to see if the split-rudder will also hold center line at full TO power. I'm rooting for you guys! 8) --gary
Please explain the split rudder more. I see impact force vs lifting force as one side stays flat (stream lined) while the other is inducing drag. Is the concept the same? Are there efficiencies in stabilization with the split rudder?
I don't get this either. The VariEze uses the split rudder to add a little extra pro-yaw drag out at the tips as well as the normal yaw moment, but I can't see the advantage of this on DarkAero because you're adding extra drag down the centre-line.
Umm.. you didn't say how the rudders stay straight. A cable is great for pulling in one direction, but it can't push. Single rudders have the other pedal to push it back to center, but you didn't describe any mechanism that does that for your split rudder system. So.. ???
Regarding the split rudder.. my basic comments would be pretty much the same as the others commenting - interesting, but not necessarily a good idea. I fly a Long EZ, at much lower speeds what you will be flying. 160 kts, max. when descending with full power :) Except for takeoff and landing (65-90 kts) I don't use my rudders. No need for that, with the arrow shaped wings of the Long EZ it keeps straight, even at takeoff. If I try to use them, at cruise speeds, 128kts with my setup, it takes considerable effort to press down on the rudder pedal. I am guessing it will be for the DarkAero too, since a split rudder is not balanced at all. When used as an airbrake, in my Long-EZ it introduces a fair amount of unstability - both rudders don't have the exact same deflection - since I am pressing them with my feet and the airfow is not clean over them, at full deflection. I much rather prefer to use my airbrake that extends from the belly of the aircraft. That is also much more effective on a Long EZ. Though max employable up to 90 kts. If you haven't yet done it, try to find a Long EZ or other Rutan inspired aircraft (easiest with a side-by side arrangement) and try the split rudders for yourself. At cruise speeds, in a conventional aircraft you need the rudder to make coordinated turns. In a swept wing aircraft (Rutan style) you almost don't need it. For airbrakes, if you can deploy your landing gear partially and if it doesn't interfere with the aircraft stability and controllability, the landing gear would make a wonderful and substantial airbrake, with no weight penalty other than the control knob for it. And I am sure you have made the calculations - what forces are acting on the split rudder at Vne and the pressure you need to push the rudder pedals with you feet.
So everytime using the Rudder deploys the Speed Brake every time? Even trimming the Rudder results in more drag? Does DarkAero have Directional Stability problem that your trying to fix with the Rudder Speedbrake? Wagging the Tail, reduced by deploying Speed brakes with Rudder deflections?
Hi I am very interested in your project DarkAero I just love how affordable it is and the range of the aircraft would you say this is a good beginner friendly aircraft I just can’t wait for the plane to be ready for its first journey through the skies and into everybody harts finally. Will the plane ever get a rocket propelled parachute system. Or BRS Aerospace: Whole Aircraft Rescovery Parachute Systems or does it already have one
The Fed's may take concern with that split rudder. Spin recovery? Cross controlling?. Slips? Slow airspeed/hi angle of attack? Hi speed flutter? Low speed ineffectiveness? What does it do with full drag and full rudder? .. any rudder left? Trim? etc. etc. That's a big box of flight testing/data that's now open, on top of an already brand new airplane with many first time designs. May be better to incorporate the splitting of the rudder separately. Or better yet... just fab a legitimate speed brake on the belly. Adding unnecessary drag any time rudder is applied seems.... silly. IMO
Clever design choice with the split rudder/airbrake. For better or worse, this style of airbrake doesn't reduce lift when deployed. Wing spoilers have the benefit of increasing tire traction, although I suppose they have their own concerns, such as difficulty in packaging without a drag penalty. I'm curious how the split rudder's drag compares to a hinged rudder at modest deflections (e.g. trimmed for P-factor at cruise).
DarkAero May I ask why not using Carbon Fiber tubes for your all tubes instead of Aluminum tubes? Any Guess when more Runaway testing? Peace Be With You.
I am totally perplexed why you build another conventional plane design and spent all the money and time to produce nothing that furthers the science . I guess every one wonts to have something custom . Is that the reason ?
Having the split rudder just moving one side if used as a rudder, makes it a speed break all the time you use it! That's not good! The articulation and the split Funktion should be a separate function, or be mixed together as such. Alot of sport pilots are doing stuff how they are teched, and don't have a good feeling for what the plane is really doing. Having them unconsciously loosing more speed as usual by using rudder inputs screams for accidents to happen. If you want to commercialize this plane design keep that in mind! Otherwise, have fun with that beast! 🤙
Won't you have a lot of drag with the split rudder when compensating for P-factor in takeoff or simply using it activley in flight? Seems an odd choice considering all the other choices biased towards efficiency / low drag. Also rather concerned about how it will work in spin recovery.
Also, is there a deliberate or inadvertent elevator input when the control sticks are deflected in the aileron axis? I LOVE the control setup, by the way!
@@joelighty409I asked Riley about this in a q & a. He replied that the elevator deflection from applying aileron would be very small and that the pilot would typically add some nose up pitch to compensate for increased bank angle.
I would consider getting rid of the split tail. Gimmicky, and complicated without much benefit. If you decide to keep it, consider staggered ribs for some regidity.
I love your work. Big fan from your start. But the split rudder makes much more drag than a standard one. You can accomplish the same load but in expense of much more drag than a standard control surface.
I'm going to have to try this split rudder in my RC planes, I just built one that would be perfect for this, I would have to add a servo and figure out how to set it up in my radio, the fun part lol NOT 😁 Thanks for the information...
Have you seen an aircraft toroidal propellor yet? A few have shown up in 3D prints for drone props… But, I haven’t seen anything since the wave of initial interest… Great question! Lots of added weight, way out on the nose, creates a lot of design hassle…. It would be nice if it has real benefits…. To match the hassle…. 😃 The DarkAero team would be a great group to make it happen.
Will this plane ever fly.....it's been over a year since they ran taxi test.....it a beautiful airplane but there has to be a serious desing flaw because it has never flown
Do you have enough leverage for one hand to over come the forces on the ailerons control surfaces? If you have 1:1 ration on the torque tube then the only lever advantage is the length of the stick. 🤔🤔🤔🤔🤔🤔
Tons of single point failures in their design for sure! The ailerons are also single rod controlled instead of a typical push-pull twin rod setup. Even the split rudder effectiveness with the short rudder couple length has me thinking they won't have much rudder effectiveness at lower airspeeds with lower prop blast at lower power.
It's remarkable to see just how consistent the entire skin of the aircraft looks, the machined tooling has paid off so well.
Most aircraft of this scale have noticeable waves and irregularities just all over the surface
It's bright white, lol.
@@FarmerFpvplenty of other white planes out there
I didn't see any mention that the long torque tubes through the wings, at the cabin, don't pivot at the tube? Hard to explain, and I don't have the correct vocabulary to properly describe, but watch closely at around the 6:00 mark. The inboard bell cranks are anchored on one of the ears?! Is it very weird that the inboard ends of the torque tubes move up and down in space?
Where’s the elevator trim? Or did you cover that already? ctrl sfc balance…what a concept.. At least nobody in your team cited “actuator stiffness” as a justification to forego balancing the ctrl sfc.😂 never mind, I haven’t watched it all the way when I asked about trim, wah wah…
This whole project is phenomenal. I wish you lads the very best of luck in the future!
Nice, heim joints, bell cranks and torque tubes, with not a whole lot of translation, so backlash should be minimal. You might want to also mention that the control surface weights, by projecting up into the airstream forward of the hinge point, also help manage control forces at higher airspeeds.
The split rudder works VERY effectively as a speed brake, I use them this way all the time on my Cozy.
I am curious what you're using as a rudder return spring - it looks like you're using push-pull cables to actuate each rudder, but I don't see space inside the rudder for a spring assembly - is it at the pedal end? If so, how do you plan to prevent buckling of the cable in push near the pedals if there is resistance at the rudder end? You'd need a decent sized spring to overcome the friction of a push/pull cable that long.
Do you engage the brakes master cylinders only after you get full rudder pedal travel? How do you ensure you can land with the rudders deployed, but without the brakes deployed? (I'm assuming the nosewheel is full castering?)
Lastly, I didn't see the roll servo, I'm curious as to where it's going to end up - it looks the only practicable place is behind the seats?
- How I heard it, the rudders are independent - with only a pull cable (spring return to centre) - ??, is the rudder deviation only from centre to full lateral deflection (left or right) ? - OR having no centre stop, the lee side rudder (low pressure) just follows the pressure side (half) to full deflection under spring action? - using the airbrakes on a steep straight-in approach sounds kind of similar to balancing regular toebrakes for yaw control, from the sound of it.. hmmm...
Some high performance lightweight RC craft also only use a (single acting) pull cable (kevlar thread/kite-line often used) for tail unit control, the tension is maintained by spring tension as is full tension deflection - balanced by servo force - (spring-pull rudder and elevator - no tensioning problems or slop can intrude)
I think they're making a mistake with the split rudders in the way they have them designed. They really need to follow each other at least somewhat past centerline for the first third of their travel before splitting, with canard aircraft a little misalignment doesn't come with a drag penalty but it certainly will with a split rudder, and especially so with conventional tractor configuration slipstream hitting the vertical. There will only be a single speed and throttle setting in which the two rudders are streamlined and together, the rest of the time one or the other will be split, meaning you'll always have a small amount of airbrake deployed. The rudder pedals should also be interconnected in their movement with airbrake function as a separate lever to actuate that simply moves two pulleys to shorten the rudder cables. This would allow standard toe brakes to be used instead of pushing the pedals to the floor and forcing the airbrakes open in order to make the toe brakes work, or having to use the dreaded piper style hand brake. You may not always want to use brakes with the airbrake deployed for whatever reason, and not being able to put any pressure on the rudder pedals during flight to avoid deploying the airbrake is going to suck.
One of the potential problems i have concern about is the spin recovery characteristics. The split rudder and location of the stabizer and elevater seem to be in positional relation ship to the rudder to cause "blanking" of the half rudder because the opposite half stays in neutral
A&P pilot here, can’t thank you enough for all of the knowledge you’re giving! Keep it up and can’t wait to see the first flight!
Always a great presentation…
Tungsten makes an interesting choice. Density, and doesn’t corrode at ordinary temperatures of aircraft operation…. And not soft like lead.
There is a recent AD for these elevator balance weights on a popular airplane because the weight was cast in a tube… and corrosion formed between the lead and the tube…. The corrosion forces expansion and the weight tries to fall apart. The problem took 20+ years to appear… but, once started the rate of oxidation increases, exacerbating the problem…
Go DarkAero!
😃
Is there an expected loss in rudder authority with your design compared to conventional designs, since only half of the rudder deflects with say a right rudder input. Wouldn't the fact the left half of the rudder remains within the line of the airflow "block" some of the airflow from adhering to the interior side of the deflecting right rudder and therefore reduce effectiveness?
It looks like it shifts the air flow point of indecision on the leading edge so that more air will flow over the clean side and move with higher speed giving more lift. Will it be _efficient_ and forceful enough for fighting *repeating* turbulent air gust rapid wing rises or more importantly immediate effective and powerful spin recovery? Imagine an inadvertent spin at aft C.O.G. with those pretty, narrow wings.
Tungsten? Depleted uranium would be more fun. It's good enough for a 747! ☢
I'm guessing it's a little more tricky to obtain...
@@LesNewell Obviously. Tungsten is the logical choice 🙂
TECHICAL PTS ONLY
Your rudder is just skin. It should've ribs. Otherwise, it gonna collapse under aero load, locking its hinge, making it catastrophic.
Too many linkages providing failure pts. Trim tabs is another set of failure points...Instead give trim tabs on stick like RC model
Longer control horns proportionally minimize backlash.
What about ICING inside the split rudder design? Will you test the push force overcoming ice adhesion? Another option is adding heat for safety. Love the concept, but Ice and Breaking concern me.
Very good point.
How is ice going to get inside an aft-facing gap, when it is closed together for the entire duration of the flight?
We designed split rudders into the Lynx suborbital space plane we were developing at XCOR for similar reasons- it allows speed brake function and also was much simpler to actuate given their locations at the wingtips. We were also able to include a slight preload against the stop to provide greater resistance to flutter, important in a supersonic aircraft.
Great explanations and great looking airplane! Reminds me Mike Arnold's AR-5.
Thanks a lot for sharing
Interesting rudder/spead brake. One thing I wonder about is propeller slipstream. On the Rutan canard airplanes the vertical stabs and rudders are outside the spiraling slipstream. On the DarkAero, it will be in the slipstream. I'll be interested to see how you deal with that, as well as rudder trim. My understand (which could very well be wrong) is that on the Rutan canards, the rudders on the winglets is more about creating drag rather than lift. Same goes with split style of flaps on other airplanes. I'm not an aeronautical engineer so I might be all wet... I'd like to see your split rudder act more conventionally with the rudder pedals and have a separate mechanism to split them. Kind of like the A-10 ailerons do. Hmmm... Or.... Leave the rudder conventional an put the speed brakes on the ailerons just like the A-10's!
Keep up the good work.
I agree with you. Rutan design is based on drag. In conventional control surfaces it’s the back side of the control surface that moves the airframe. It’s a wing you might say creating lift. Left rudder input means the right side of the vertical fin and right side skin of the rudder making a positive airfoil moving the tail in the left direction. I question if this will work well. I’m not an engineer but have been designing and building model aircraft all of my life for 50 years or so. Have studied design for decades. I guess we will know one day. Great project!!!
Very interesting rudder design, really clever double identity for a rudder. However, even though I don't see this bird doing dive bombing, the dive bombers in WWII also had an air brake, which didn't work until they poked it full of holes. Before the holes, the dive flaps ripped themselves off the airplane in some dives. There's going to be quite a vacuum in between your rudder panels. They're also small, unlike the surfaces of a dive brake, so making them work without unexpected consequences should be easy. Holes near the very front of the control surface should do, and won't interfere with the forward flight aerodynamics of the surface, but it will do the pilot and structure a favor. They can be made as decorative as they are functional.
I was going to mention the drag. If you need to fly with a trim, you'd be flying with a parasitic drag. Anyway, yours went well beyond that!
They didn't have carbon fiber back in WW2. But it is a good idea if they need to.
@@LawyerPapa Ouhhh thats a solid concern.
How will you handle constant yaw inputs in cruise flight? Won’t a constant split be inefficient?
Like any airplane, the pilot has to learn its quirks. The cork of this is you can't push hard on both of the rudder pedals at the same time
The Long EZ 'rudders' are somewhat required to be airbrakes, since they use a different principle to normal rudders to yaw the plane.
Normal rudders apply lateral lift to the tail to pivot about the center of gravity. Since the Long EZ rudders are more to the sides rather than behind the CoG, the force required to pivot around the CoG is almost straight backward, ie, drag. And they need to be differential so that their is a net torque.
If the EZ rudders were set up to act in unison, in the same direction, you would find that it would barely yaw.
edit: I checked my plans and the Cozy definitely has a shorter rudder moment arm than a comparable 172, previous comment deleted. oops!
The LongEZ and Cozy both place the rudder aft of the Center of Gravity. Rudder deflection yaws the aircraft in the conventional sense. Yaw control also benefits from some increased drag located far outboard. But the drag increment is minuscule compared to lift increment from a deflected flap. This is self evident in all flapped airfoil wind tunnel measurements.
You might want to consider a lockout for the split rudder for takeoff and climb. Canard flyers of various makes have had issues during engine outs of panic stomping on both rudder pedals, exacerbating the emergency. This is of course, alleviated with training. Also, a lockout would keep the passenger from inadvertently inputting while shifting their position, ect.
Does a control lockout not have its own safety challenges?
You wouldn't want to lock out the rudders during takeoff, climb, or any other phase of flight since they are required for directional control.
@@DarkAeroInc only lock out the split rudder functionality. When locked, it should behave as a conventional single rudder
The ability to flip a switch to convert the rudder(s) into a single control surface would inherently be safer. (If this function is actually desired) Failures to the pins/flanges shouldn't lead to any particular dangers.
@@codeforge3301 This is what I meant to convey. Thanks.
The split rudder is so sick
I agree. I imagine there's a small aerodynamic penalty to using split rudders. I'm pretty sure the split rudder has more drag in use than a conventional rudder. Having a speed brake likely makes any loses worth it.
Was wondering if that could be a replacement for ... flaps. Thoughts?
@@fdelacou- It could replace flaps for giving drag while reducing altitude without gaining airspeed. Won’t add lift for slower takeoff and landing speeds though.
No! Not sick but good!
@@fdelacou NO. Flaps increase lift and drag, important to minimize and bleed KE during landing. Lift is critical for this. Flap extension is typically not allowed at high speeds due to high loading they can create.
I used to fly the SAAB 340 and it had the most amazing redundant elevator system. Basically the left control column controlled the left half of the elevator and the right control column controlled the right half of the elevator. Normally they'd work together as one unit as there was a friction and mechanical plate that meant that if one side moved the other side moved as well. But crucially if part of the system jammed you could overpower the linkage between the two sides and still be able to operate at least half of the elevator. I always thought this was an amazing way to provide redundancy.
I never tried the split rudder although I thought a lot about it. I have flown canard aircraft so I understand the speed brake part of it. Good job! Also it looks like you have some differential in the ailerons. Very good! Something I did a lot was flattening and widening the aileron counterweights so they tuck up inside the wing tips only when the aileron deflects down but the weight enters the wind stream when the aileron deflects up. This adds some parasite drag to the to the up aileron side of the aircraft thus reducing the amount of rudder required to maintain coordinated flight. It's good to see some young people that know how to think out good design. Keep it going and be careful. Thanks for the videos!
I am predicting the rudder will be changed after flight tests. It would be more sensible to let the split rudder stay together as it moves left and right and only opens up when a speed brake is actually required. Easy enough to do with a mixer.
On an aircraft designed for utmost efficiency, getting a drag brake opening every time you use the rudder makes no sense.
They would be wise to have a plan B.
_Trim tabs. Trim tabs? Trim tabs!_
You use uber-expensive _tungsten_ in preference to super-cheap lead, in a presumption to eek out a tiny advantage in drag (in flight regimes whereof drag is sometimes desired anyway), when at the same time you use trim tabs which _always_ introduce weight, complexity, and/or (unnecessary) parasitic drag in _all_ flight regimes?
It´s just as well that you can distract the consumer with that cool split rudder, as then there is less chance you need rationalize a technology that even a century ago had multiple alternate engineering solutions and workarounds.
I didn’t hear anything about designing out flutter? This is of great technical interest to me. It is also the practical speed limit for many airframes, assuming they have lots of hp like this one. Would especially be applicable to high powered turbo normalized aircraft
yer split rudder design is totally D U M B.!!!
it is going to act as an air brake, ANY/EVERY TIME it's used.!!!
You've probably already answered this but how is trim done?
Do you have a rudder trim system ?
+1 for rudder trim!
Not always needed… but always appreciated! Really nice for those long climbs to altitude… and extra speed during the descent.
Kinda like a yaw damper for the auto-pilot too… not a requirement, but really nice to have in the bumps…
Don’t fly sideways!
😃
We don’t have rudder trim on the prototype, but it wouldn’t be hard to implement if a builder wanted it.
Ngl, I love everything about the split rudder aside from the control scheme you've selected. Conventional rudder pedals (push one and other moves opposite) with a seperate speed brake lever similar to what youd see on a jet's throttle quadrant would be much better as far as avoiding inadvertent speed brake application and making the transition from other aircraft more seamless.
ngl, yeranidiot see my comment above
As always the ailerons will create some adverse yaw that will have to be counteracted by rudder. Unfortunately the split rudder is going to cause a lot of drag during routine turning.
I like the split rudder as an air brake. But I hope you have considered how the airplane will react in flight with only half of the surface deflecting?
With this, you are splitting the airflow, creating a void of air forming low pressure pocket behind the airplane. This means any time you use the rudder (usually at low speed TO or landing) you are adding a lot of drag, which could decelerate the plane at a critical moment.
Another negative aspect I foresee is that while one side is deflecting, the other side is still in place, acting as a vertical stabiliser. I believe this will negate a lot of the effective yaw control and may require a lot more deflection to get an adequate response.
Just my thoughts. Would love to see how you guys have tested this concept.
The drag force is reduced at lower speeds, and it's likely that the aerodynamic force when using normal rudder input will pull the opposite rudder along (unless the surfaces are blocked from moving across the center point).
The independent rudders are great. A very safe way to operate a speed brake without forgetting the boards are out. Yes, this happens, even with highly trained and experienced airline pilots they forget to stow the speed brakes.
Really proud of you guys, I have been following you guys for 3 YEARS. If I get a visa to the US, I must come and visit you guys. The consistency is amazing.
It is staggeringly banal to spend so much viewer time 'explaining' how conventional three axis controls work - do you really think that anybody needs to be 'educated' like this ? Explaining how yours wheels work might be about as informative .. The 'split' rudder is not novel either - my "Opal" design from 1975 and published drawings show this and explain the glide path control function (familiar to all glider pilots ) Grumman Intruder, B2 bomber and lots of others use the same chordwise split for drag modulation -you lose a LOT of rudder power by not moving BOTH halves in assymetric deflection as you seem to indicate (ie the yaw function) and I think that your vertical tail is already slightly undersized especially in view of the long nose and high power installed . Your design follows the well worn path of overpowered 'boy's toys' in the vein of the Polen special, Brokaw, Sx300 and similar types of 'pseudo' WW2 fighters -- but lack the purpose driven design criteria of a real period fighter . Once you are reasonably high there is no apparent 'speed' as such like a race car or motorbike provides and 'beat ups' or dangerous low flying hardly amount to a design justification for 'thrills' . If point to point speed in real transport is the idea then for private citizens the real measure ought to be DOOR to DOOR which is the relevant measure and is hobbled by the logistics of getting to and from your 'friendly local long hard surfaced runwayed, hangar equipped, fuel on tap etc '"Local" airport .... usually miles from where you live or need to go on 'arrival' . It would be much better for you guys to use your resources and obvious engineering talents on something that addresses this USEFUL goal and might contribute something worthwhile to society and aviation in a manner that fosters public acceptance and even enthusiasm for general aviation (indulgences that only usually appear as accident reports in the public eye or show aviation as an adolescent extravagance in a cash strapped economy with real problems that aviation might better address ... look into Advanced air mobility, roadability and similar googleable terms for 'inspiration'.
Cross outs are unintentional -can't help them on this ancient laptop but apologies all the same.
You guys are awesome! Everything is very well thought out. The split rudder is a great feature. Using it to slow the plane down is very nice. I have to ask, in turns, does the other half, the straight half, hinder the turning ability of the turning half, enough to notice? Do the halves open up enough to maybe offset any drag? Again, great job! I hope to have the money to buy one of your airCRAFT one day! Take care
Very cool. You didn't mention nose gear steering. How will that work? Maybe include with the secondary controls discussion?
It looks like it's castering (ruclips.net/video/H8Ugh2fzd0I/видео.html) but this still involves controlling the braking mechanism. I didn't look carefully for past videos on this.
Yes they chose to go with a free castering nose wheel. Steering is handled by differential breaking and rudder at high ground speed.
Great video, as always. In addition to clearly explaining the basic operation of your control system, I especially liked how you quickly touched on the considerations that went into the design; such as goals to minimize friction, backlash, compliance, and weight while also ensuring easy of service.
Is there any increased icing risk in the split rudder?
Happy reservation holder.. keep going
Nice one! Guess next month the video will be about flaps and trims? And what about the antennas? I’m really curious about those…
From the first minute of the video I was wondering the same thing. Where are the flaps and trim tabs?
they have been doing this for years, never seen anything fly.@@rmarsh3309
You should reconsider the current rudder actuation. As @aaronhammond7297 mentioned in a comment a few days ago the Long EZ 'rudders' are somewhat required to be airbrakes because the force required to pivot around the CoG is almost straight backward, ie, drag. Which is not true for your design. Every time one will actuate the rudder it seems that it will also create some serious drag, due to rudder's size. Considering that you designed the plane for speed, that's a major oversight. Sometimes being different is not being better. You can keep the split rudder design, but the halves should move together, unless the brake is actually wanted and applied intentionally some other way.
Why you didn't use flaperons if your goal is minimizing the weight so much? 🤔🤔
They obviously haven't figured that out yet.🙄
How bad is the performance loss during initial climb when using a lot of right rudder? It seems like you’d be trying to climb with the speed break basically partially deployed if you have a consistent rudder input in
Such a gorgeous plane
Mmm ok
Very cool, congrats on the innovative design! I'm still looking forward to HS taxi testing/ TO roll testing. I looked at the similarities/differences between the DarkAero and a TBM for TO roll (for P-factor). They are somewhat (loosely) the same. The TBM has a large rudder, and needs it to hold center line on TO. It will be interesting to see if the split-rudder will also hold center line at full TO power. I'm rooting for you guys! 8) --gary
thanks question: you dont need to balance split flaps or split ruder right? this question includes balance via weight and aiirodynamicaly.
Is there a differential in the ailerons between up and down deflection or is the travel the same? Cheers and good luck.
I'm excited for DarkAero! Approximately when will the maiden take place?
You won't get an answer..five years in so far
In 1965, the Payen Arbalète PA60 was already using such a system that inspired Rockwell for the space shuttle...
Are there no vortexes produced at the end of the wings, increasing drag?
Still wondering how the mechanism works, can you make a detailed video on how those flaps controlled ?
Please explain the split rudder more. I see impact force vs lifting force as one side stays flat (stream lined) while the other is inducing drag. Is the concept the same? Are there efficiencies in stabilization with the split rudder?
I don't get this either. The VariEze uses the split rudder to add a little extra pro-yaw drag out at the tips as well as the normal yaw moment, but I can't see the advantage of this on DarkAero because you're adding extra drag down the centre-line.
Umm.. you didn't say how the rudders stay straight. A cable is great for pulling in one direction, but it can't push. Single rudders have the other pedal to push it back to center, but you didn't describe any mechanism that does that for your split rudder system. So.. ???
Regarding the split rudder.. my basic comments would be pretty much the same as the others commenting - interesting, but not necessarily a good idea.
I fly a Long EZ, at much lower speeds what you will be flying. 160 kts, max. when descending with full power :)
Except for takeoff and landing (65-90 kts) I don't use my rudders. No need for that, with the arrow shaped wings of the Long EZ it keeps straight, even at takeoff.
If I try to use them, at cruise speeds, 128kts with my setup, it takes considerable effort to press down on the rudder pedal. I am guessing it will be for the DarkAero too, since a split rudder is not balanced at all.
When used as an airbrake, in my Long-EZ it introduces a fair amount of unstability - both rudders don't have the exact same deflection - since I am pressing them with my feet and the airfow is not clean over them, at full deflection.
I much rather prefer to use my airbrake that extends from the belly of the aircraft. That is also much more effective on a Long EZ. Though max employable up to 90 kts.
If you haven't yet done it, try to find a Long EZ or other Rutan inspired aircraft (easiest with a side-by side arrangement) and try the split rudders for yourself.
At cruise speeds, in a conventional aircraft you need the rudder to make coordinated turns. In a swept wing aircraft (Rutan style) you almost don't need it.
For airbrakes, if you can deploy your landing gear partially and if it doesn't interfere with the aircraft stability and controllability, the landing gear would make a wonderful and substantial airbrake, with no weight penalty other than the control knob for it.
And I am sure you have made the calculations - what forces are acting on the split rudder at Vne and the pressure you need to push the rudder pedals with you feet.
So everytime using the Rudder deploys the Speed Brake every time? Even trimming the Rudder results in more drag?
Does DarkAero have Directional Stability problem that your trying to fix with the Rudder Speedbrake? Wagging the Tail, reduced by deploying Speed brakes with Rudder deflections?
Hi I am very interested in your project DarkAero I just love how affordable it is and the range of the aircraft would you say this is a good beginner friendly aircraft I just can’t wait for the plane to be ready for its first journey through the skies and into everybody harts finally. Will the plane ever get a
rocket propelled parachute system. Or BRS Aerospace: Whole Aircraft
Rescovery Parachute Systems or does it already have one
The Fed's may take concern with that split rudder. Spin recovery? Cross controlling?. Slips? Slow airspeed/hi angle of attack? Hi speed flutter? Low speed ineffectiveness? What does it do with full drag and full rudder? .. any rudder left? Trim? etc. etc. That's a big box of flight testing/data that's now open, on top of an already brand new airplane with many first time designs. May be better to incorporate the splitting of the rudder separately. Or better yet... just fab a legitimate speed brake on the belly.
Adding unnecessary drag any time rudder is applied seems.... silly. IMO
Clever design choice with the split rudder/airbrake. For better or worse, this style of airbrake doesn't reduce lift when deployed. Wing spoilers have the benefit of increasing tire traction, although I suppose they have their own concerns, such as difficulty in packaging without a drag penalty.
I'm curious how the split rudder's drag compares to a hinged rudder at modest deflections (e.g. trimmed for P-factor at cruise).
The most advanced airplane 🛫 today 🛫🤙🏻🏆☝🏻💪🏼 looking forward to more videos ty
DarkAero May I ask why not using Carbon Fiber tubes for your all tubes instead of Aluminum tubes? Any Guess when more Runaway testing? Peace Be With You.
I am totally perplexed why you build another conventional plane design and spent all the money and time to produce nothing that furthers the science . I guess every one wonts to have something custom . Is that the reason ?
Carbon fiber wrapped aluminum tubes, should do the trick.
Please get/use a better flashlight/headlight -- something with great CRI
Having the split rudder just moving one side if used as a rudder, makes it a speed break all the time you use it!
That's not good!
The articulation and the split Funktion should be a separate function, or be mixed together as such.
Alot of sport pilots are doing stuff how they are teched, and don't have a good feeling for what the plane is really doing.
Having them unconsciously loosing more speed as usual by using rudder inputs screams for accidents to happen.
If you want to commercialize this plane design keep that in mind!
Otherwise, have fun with that beast! 🤙
Won't you have a lot of drag with the split rudder when compensating for P-factor in takeoff or simply using it activley in flight? Seems an odd choice considering all the other choices biased towards efficiency / low drag. Also rather concerned about how it will work in spin recovery.
Is DarkAero ever going to finish this thing, or is it just for the memes and making RUclips videos?
You may have covered it elsewhere, but I would be interested to hear about the flutter considerations for your split rudder assembly.
Also, is there a deliberate or inadvertent elevator input when the control sticks are deflected in the aileron axis? I LOVE the control setup, by the way!
@@joelighty409I asked Riley about this in a q & a. He replied that the elevator deflection from applying aileron would be very small and that the pilot would typically add some nose up pitch to compensate for increased bank angle.
Thanks!@@rickhearn5899
How strong and durable is the material? Real flight at 200mph how much damage does turbulence whip damage?
I would consider getting rid of the split tail. Gimmicky, and complicated without much benefit. If you decide to keep it, consider staggered ribs for some regidity.
I love your work. Big fan from your start. But the split rudder makes much more drag than a standard one. You can accomplish the same load but in expense of much more drag than a standard control surface.
How does the roll not bleed into pitch control? When you move the stick sideways, it seems that the pitch linkage would move a bit forward?
I'm going to have to try this split rudder in my RC planes, I just built one that would be perfect for this, I would have to add a servo and figure out how to set it up in my radio, the fun part lol NOT 😁 Thanks for the information...
Battery planes are a gimmick. You can do the same thing with a plus sized RC plane. 0/10
Have you thought of including a toroidal propeller.
Reduced noise, higher performance. Amazing.
Have you seen an aircraft toroidal propellor yet?
A few have shown up in 3D prints for drone props…
But, I haven’t seen anything since the wave of initial interest…
Great question!
Lots of added weight, way out on the nose, creates a lot of design hassle….
It would be nice if it has real benefits…. To match the hassle…. 😃
The DarkAero team would be a great group to make it happen.
Why is the fuselage so long? Could the cruising drag be reduced if the empennage is closer to the cockpit?
what are you guys doing about confliced input /panic input on the rudder?
you might just end up with a huge speedbrake deployed at takeoff
You split it just to have a speed brake? That seem strange to me. Isn't that going away from the "keep it simple" idea?
IMHO the split rudders have been done before. They don’t work well.
have a nice day, how are you? are you ok? When will the 275 mph plane be released? The speed of your planes is very good.
Will this plane ever fly.....it's been over a year since they ran taxi test.....it a beautiful airplane but there has to be a serious desing flaw because it has never flown
Great video as always!
Is there an interlock of sorts that keeps the rudders from going into speed brake mode while in flight?
One doubt, the split rudder can in thesis act differently because both sides would never act equaly and cause yaw?
How do the wheel brakes work with split rudders?
Though your methods and design may be a little different, what you are doing has already been done. No offense to your efforts.
So every rudder input comes with some braking. I fail to see the wisdom in that.
You know an ordinary rudder would add drag too... Even add a bit of opposite aileron for a bit more...
With the rudder pedals doing so many things, how do you apply the brakes?
why dont you guys use fly-by-wire controls? it seems that fly-by-wire could both reduce weight and be easier to fit in the small airframe
No twins use a split rudder. Carrying passengers demands no safety compromises.
The P51 is faster. Its old it’s metal and it carries more has more range and it shoots big bullets.
Do you have enough leverage for one hand to over come the forces on the ailerons control surfaces? If you have 1:1 ration on the torque tube then the only lever advantage is the length of the stick. 🤔🤔🤔🤔🤔🤔
I would glue that split ruder together... Other than that, it is looking very good.
So, no trim tabs or flaps for this plane? Oh...last few seconds of the video both are mentioned.
gd i've been dreaming of a plane like this for years.
If only I was rich!
Why is your elevator torque tube off the center of rotation? Space constraints?
Why not have both rudder planes deflect left/right?
Is there any redundancy in the system? Seeing that the elevator is connected via a single push rod, does that mean there is a single point of failure?
Tons of single point failures in their design for sure! The ailerons are also single rod controlled instead of a typical push-pull twin rod setup. Even the split rudder effectiveness with the short rudder couple length has me thinking they won't have much rudder effectiveness at lower airspeeds with lower prop blast at lower power.
the tail design seems really interesting, I guess that somehow reduce drag?
Is this for children?
Yes. Kids love airplanes.
Flaps? Aha just watched to the very end and have seen the flaps LOL!