Big Size PBY Catalina RC Model Maiden Flight : Almost Crash 3 Times!!
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- Опубликовано: 28 сен 2024
- I thought this was going to be an easy maiden flight, but I was totally wrong. The RC plane is PBY Catalina with 90 inch wingspan, with 6,2 pounds weight. It made out of 5mm Depron foam and 3mm plywood formers. There's still some part of the plane that needed to be fixed so it can fly normally, but I'm very optimistic that it can fly nicely next week on the next flight test again.
If it’s not wing or stabiliser twist or cg causing the porpoising it could be that because the engines are mounted above the vertical cg that when the engines are on it is trying to rotate the plane downward (around the vertical cg). When the engines are off, as they were in the glide, then the plane flies normally. So my second suggestion is to try a upthrust on the engines instead of downthrust.
This would also explain why the plane is sticking to the ground on take off under power. An interesting test might be to get it up to full speed on the ground, cut the motor and then try to lift up off the ground very slightly then put it back down again. Minimise any wheel drag too. They could be slowing the plane down on take off.
I just want to add a bit about high mounted motors that are mounted above the vertical cg. If you look at the bixler pusher plane you will notice that the engine has a severe amount of downthrust and I believe this is to help stop the plane rotating around the vertical cg when it is under power. But the bixler has the motors behind the cg, hence downthrust. Since your motors are in front of cg then upthrust should give the same result.
It make senses Mark, on 3rd flight after I add more down thrust it became worse than before, even tho I moved the CG back again. Thanks, I will try that on the next flight. Actually in the real plane is also has slightly up thrust, but when I design this plans, I ignore it and make it straight. I thought it should be down thrust, but maybe I was wrong again.
@@JuliusPerdana
Am really looking foward to seeing if it’s a lack of up thrust that’s the problem.
All flying boats have high mounted engines to clear the spray,so they need to be offset up to unstick the nose on take of.
Fun fact the German M E 109 fighter actually had upthrust on the full size!
I was going to write the same thing as Mark - but no need to. Thank you Mark.
Julius, if you Google "high thrust line aircraft" you will find confirmation of Mark's advice. The high thrust line compared with the "vertical" centre of gravity results in an effect like down-thrust, only MUCH stronger.
@@JuliusPerdana There is a few people here interested to see if upthrust solves the problem, including me. I wonder how much it will need. I think the amount of upthrust also depends on the location of the CG with respect to the motor/prop location.
Hello Julius, I think it's great that you also show things that don't work from the start. Respect!! I like the model. Thanks!
You are welcome!
Its crazy how fast you build your Planes really cool Projects
thanks, foam is easy to use
Beautiful plane!
I am glad you didnt crash the plane on your maiden flight! Good saves.
Dear Julius, don't worry about the inconveniences. Aeromodelling is also this, otherwise it wouldn't be fun. I am sure that, thanks to your construction skills, you will be able to perfectly eliminate what is wrong in flight. You've built a great model! Compliments!!! Greetings from Italy.
The shapes are getting more and more complex.. beautiful plane and a great build! Looking forward to the next flights!
Thanks a lot!
That runway is like a RC plane magnet😁😁, I love the way you edit you're videos and how your airplanes turn out and to be honest you are the best on RUclips
I love your videos because you are always honest in showing your joys and disappointments and not just your successes, as we often see with other RC youtubers
Thank you so much!
I was excitedly waiting for this video, and i was not disappointed. This is an amazing build. Great work! I am excited to see you refine this build.
The PBY Catalina is one of my favorite planes too!
Wow, so beautiful plane
Thanks a lot!
Thank you for sharing your thinking as you troubleshoot your model. This is helpful for all of us to learn from your experience.
Thanks for watching!
Still working on DC-3 tookna long pause in building. Old age . This is a beautiful model, you have built, only saved by to talents with the controls. My 3 versions of the YRF-4E sit in various stages awaiting my will to try 3 more times . But finding a place to fly is becoming difficult. I'm sure you will find a cure for instabilities you encountered on maiden. Yes you are a fine toy maker, thanks for sharing your designs , one for my YRF-4E mods is based on your F4 . Take care.
Great video! I love the trouble shooting process. Will be really interested in next week’s flight with no washout!
The Best builder.I learned a lot from you.Waiting to fix all problems and fly from airport and water. Do Grumman Goose for the summer. Congratulations.
Great suggestion!
I once built an airplane with airfoil that had sharp leading and it flew just like your Catalina. Rounding the leading edge solved the problem.
Julius, there are mistakes and successes... people's lives are like that too, isn't it? Soon we will be seeing Catlina flying "round" - Congratulations!!!!
Are the engines angled upward like the real plane? If not that might be why the plane sticks to the ground
That is a beautiful airplane. Sounds like you might be on the right track for getting it to fly correctly. I look forward to seeing it fly beautifully next time.
That's the plan!
Congratulations for the model, very nice. It's tail heavy in my opinion, maybe you should move the center of gravity further forward? I look forward to the next test.
Thanks for the tip
I've been waiting for this video, started wanting to build a Catalina cardstock glider and you'd already started yours. Been keen to get blender experience as well
Hope you enjoy it!
your vids are amazing 👍👍👍
Thank you so much 😀
As usual your aircraft are inspirational I always look forward to your next creation. As long as you have a slightly positive attitude on the landing gear I would then look at up thrust on the motors as down thrust is pushing the nose wheel into the ground as the thrust is above the centre line pulling the nose down. The fact that it glides OK points to your thrust line being the possible issue.
Thank you very much!
Time 1:14 el borde de ataque debe ser mas redondeado y tener cuidado con la terminación, no debe tener filo para que el aire se direccione mejor en el intrados y el extrados. También debe ser menos flexible o mas rigida el ala para soportar el peso del modelo. saludos y suerte la próxima.
Luckily you're a good pilot, if it was me the plane was in pieces on the first takeoff 😂
Wow, you saved it. Where did you buy the retractable landing gears for this kit, please
?
no, it fixed and detachable not retract
@@JuliusPerdana thank you
I hope it's not what I think it is ,I remember building a RC cessna182 /1.5m wingspan in 2021 and I made the trailing edge way to low and the airplane flew good at slow speed but when pushing the throttle the airplane just picked down ,from that moment I learned 2 things 1. Keep the trailing edge on the center so that air could go over the wing much smoother and make the edge close to sharp edge ,hope it helps
yes it's the same on me, but in my catalina it's only on both wingtip to a quarter of the wing that have negative angle
@@JuliusPerdana I really hope you can make it fly better🤞
Akhirnya .nonton juga.mantab om
where are you flying this catalina?
Rumpin bogor/serpong
@@JuliusPerdana wah. Matursuwun pak. Saya mau terbangin disitulah suatu saat ketika sudah membuat 1 drone.
Great video…lots of good learning
Glad you think so!
You never mentioned ever putting some trim on the elevator. To me it looked like you needed to play with the trim to see if it will fly straight with power on.
Maybe I was too busy not to crash it so I havent have chance trying to trim.
@@JuliusPerdana I understand. You had your hands full. But trimming it out in the air is the first thing I do. Sometimes with someone else to help.
I think something is wrong with your elevator angle. Looks so good your plane by the way.
Bau doch mal ein Modell im Maßstab 1:2 aus Depron.
In Deutschland hat mal einer eine Fokker im Maßstab 1:2 gebaut.
Best regards from Germany! 👍
I will not be first, but 0 angle of incidence on the wing and stabilizer is not a perfect setup. Also, 30% CG is a "brave" setup for the maiden. I will set CG at 20-25% of the chord and set the elevator a bit up to set a little downforce at the stabilizer.
Can you measure the angle of the wing tip twist? In most models, it is very small - up to 2 degrees.
Painting as always - perfect!
You need UP thrust...like the full scale plane...thrust line way above cg...
something i used to notice in PBY documentaries was how exaggerated the angle of incidence looked on the PBY, something i didn't see on your model which could be contributing to it's unwillingness to get airborne.........
it was model from the real one, it has that high AOI, if you look at it in real life maybe you'll see it. In the video it was obscured by the wingtip washout so that high AOI not too visible
btw it finally fly normally in this video ruclips.net/video/gNLytNEmV9o/видео.html
Dear Julius, from watching the video closely I think the main problem with this good looking large model is that the wings are simply not strong enough, span wise and especially torsionaly as the wings look like they are twisting too easily. Wash out is a good idea but your wing needs to be stiff enough to do it otherwise they will twist downwards during take off causing your plane to stick to the ground and then when you are forced to pull hard on the elevator they will twist upwards causing your plane lurch upwards into the air as seen in the video, this lack of torsional rigidity in the wings will make your plane feel very pitch unstable regardless of where you put the CG or how you set the wing incidence, you need stronger stiffer wings !! :)
Covering the wings in fibre tape might work a little bit but not enough I think.... the model is too large for this bodge to work.
I think the way solve this properly is to rebuild the wings and to make the spar from wood and use more ribs. My recommendation is to use 12mm thick foam with 12mm x 3mm wood cap strips top and bottom and sandwich the front and back of the spar with a 1mm plywood shear web. This will add about a half a kilo of weight but the model is more than large enough to cope with this but the wing will be a lot stronger and stiffer and will fly much better !! :)
Also you will want to have ribs every 150mm in front and behind the spar too, this will really help to add extra stiffness to the wing for not much more weight, if you use foam for the ribs you will want them to be at least 6mm thick.
Lastly using 3mm lite ply for the ribs where the wings join and where the wing joiner tube ends to create a hard point along the spar will be needed too. All in these modifications will weigh less then a kilo, a price well worth paying for your nice looking model to fly well :)
I have designed, built and flown many models and I have made many mistakes too of which not making the wings stiff enough was one of them, I hope what I have said might be of use to you.
I wish you luck and I look forward to hearing what you think and to watching your next videos, best wishes !! :)
I was thinking wing twist as well. You can see during take off how much the wings are flapping like a bird, and I suspect the wings are not stiff enough. I think the twist is causing it to pull one way and cause the wing to twist even more. It could also be that the stabilizer is not stiff enough and the twist causes it to go to one extreme until it slows, then the other extreme in the opposite direction.
Although it was porpoising during take off, I don’t think the 30% cg was an issue as you proved by moving it back to 25%. Either should work, but the further forward it is the harder it is for the tail to to push the stabiliser down for take off.
The wing or stabilizer twist might also be causing it to stick to the ground. Alternatively the main wheels are too far back and making it harder to rotate for take off.
I had a similar issue with a foam Radian Pro glider that would tend to twist the wing in a dive that caused it to twist more keeping it in a dive. Only an extreme elevator input would pull it out and once the plane slowed down it behaved normally.
A very nice looking plane made from depron (I think you said). It amazing how realistic it looks.
@@markcummings150 .... I really think that the main issue is that the wings are not stiff enough torsionaly ... wheel position looks fine , elevator looks stiff enough plus they wouldn't cause the plane to stick to the runway, porpoising was most likely due to surface and a bouncy front wheel as well as the wings flapping about.
Stiffer wings and maybe a degree or two increase in wing incidence will solve the fundamental issues then you can fine tune the thrust angle of the motors etc.
Wooden box section spar and lots more ribs is the fix here.
I think the wing is already stiff enough, even sturdier than any of my other planes on previous videos. It's the motor thrust angle, it should be up thrust not down thrust.
@@JuliusPerdana ... doesn't seem like it looking at the video due to the flapping of the wings and the flight behaviour but perhaps I'm seeing it wrong. Also, compared to your other models this is much larger and stiffness is therefore relative but I remain open to being wrong about this. I hope you can forgive me for not agreeing :)
Either way I wish you luck in fixing this and I look forward to your next video :)
you mean flapping when it flying up and down? No foam wing can withstand that kind of flight, I think I wont over build it, it's rigid enough for me for foam plane.
Super project
I believe the wing profile is too thick and has too much area (I know this is a copy from blueprints of the real thing but it won't behave the same). The wing generates too much lift (and the twisted wing adds additional lift at low speed). I would add more ballast to the plane.
Also shorten the back landing gear height so the plane points upwards so it doesn't stick to the ground (so it will naturally lift off instead of using excessive elevator).
no it's not too thick, considering the wide wing chord too (34 cm)
Build yourself a wind tunnel with a window to observe behaviours in flow
Your builds are getting better and better, this is your finest work yet aesthetically, maybe you need to spend some time on fundamentals and focus on some solid proof of theory models before getting back to beautiful show pieces. I think your wing or stab is warping at speed but I can’t be sure from a video - it’s likely to do with thrust line - I just hate seeing you crash or nearly crash so many times
why not both? learning while doing what I like, you know I hate ugly models lol. It will fly good eventually, it's just a process, when sometimes I hide it so you just see the successful ones.
Mantap om
Outer wing portions have anhedral
Reproduce to dihedral
Punya sy ini nggak kuwat terbang kurang besar apanya mas
Bikin apa mas?
Need left all command but set 35% exponential
I use 20% expo on ail and 50% on rud and ele
I see in the video your wingtips are too much negitive dyhedral. The bend way to much during the porpusing
Wow,keren.. i mean cool
try land it in water and if possible try adding a bomb bay door
for sure!
If anyone can do it you can 👍
Please sr71
ok
Bang mending buat Vidio yang b indo nya juga
Orang kita kan bisa banyak bahasa termasuk English, orang luar ga bisa Bahasa Indonesia
HI JULIUS MY FRIEND. THE SAME PROBLEM LIKE A10 WORTH, A FEW DAYS LATER!! MAYBY IS LEATLE MOOVE IN ALEVATOR?? AND SORRY MY FRIEND I SHOW THE NEW MODEL THE WING IS NOT HAVE A DIEDRAL, THE SAME LIKE A10 WORTH! OR MABY HE WANTS MORE BIG MOTOR, MORE POWER TOO TAKE PLANE IN THE SKY!! THE SAME PROBLEM IN TWO MODELS!! I HOPE TWO FINDE THE ANSWER!! GRATE JOB!! THE MODEL IS BLUE AND SHINE VERY MATCH!! WE TALK AGAIN....
a theory: you made the right choice to decrease the elevator movement, when the propellers are running it blows lots more air over the tail which makes the elevator more sensitive. that may explain why the plane could glide nicely, because it didn't have the propellers blowing over the tail. adding Expo to the elevator should help too. a beautiful model, I've learned so much from your amazing builds, hope to see the catalina back in the air soon!
I also would like to say that your contribution to the RC world is enormous. Through your plans you inspire every hobbyist to build. For FREE. You are a good man. Thank you so much!!!!
Wow, thank you!
Here,here...
I think you are tail heavy. With the high mounted motors, the props push the nose down too. If this was on water it would be very visible, digging the nose into the water. The main wing needs about 2-3 degrees angle of attack too. The props should have maybe one degree more in addition. The tail sensitivity is also obvious. Washout does not matter here, no need to address that. A slightly higher nose wheel will not hurt either.
Be persistant, and you will get there in the end! Good job so far!
Love This Build. You are getting more awesome by each day and with every build. My eyes had been set on receiving a notification from Your channel.
Glad you enjoy it!
That's some great pilot saving! Nice job and it's good to see all the things you've done. I had a model that behaved the same way and it turned out that the thrust was above and basically kept pushing the nose down. I actually needed UP-thrust to help. You could still be tail heavy, though. I just know that when the engines are above the "normal" thrust line, it sort of acts like a pendulum and forces the nose down. Great job and looking forward to your further success! -Dan
I think you need slight upthrust like the full-size.good luck
What a wonderful styro plane! The dorsal canopies are awesome. Gratulations!
About the AOI: I found a picture of a Catalina on the runway. I found that the AOI of the main wing and the engines are pitched up about 3° when it stands horizontally. In Your video the main wing has next to no AOI. So the plane has to roll pretty fast before it gets sufficient lift.
I think that is the reason for the down pitch when under power too. Look at trainer models with a pusher on the top of the wing. The pitch of these motors is insane and the motors look like their purpose is to ram the plane into the ground.
The first thing I would try is increasing the AOI and adapting the elevator accordingly so You get a angle difference about one degree. This alone should make the plane lifting off much easier.
About the main gear: Does the plane roll around the pitch axis when You try to lift off? If not, consider moving the main wheels a little bit closer to the CG. Try pushing the tail down when the plane stands on the ground. If You have to push hard, the wheels are too far back. The tail should almost stay on the ground when pushed down and the plane is pitched backward.
Last point is about the 30% CG. The wing is not square but tapered forward. So it's point af pressure the further forward and so should be the CG. The 30% fits for square wing profiles and sufficiently big elevators. Yours elevators seem to be quite small. The smaller the further forward is the resulting point of pressure (or neutral point). Accordingly the CG has to move more to the front. That could help easying the elevator sensitivty too.
BTW the plane looked tail heavy as it sailed fantasticly and at some points the tail even dropped.
Mine has about 3 degree AOI but maybe it's not visible because the outer wing has washout twist, a bit negative pitch on the wing tip
I had a similar problem when I designed and built a FA-18. The problem I think you are having is that your nose gear is too short (or mains too long). This is causing a flat or negative angle of attack during you takeoff, making the nose stick to the ground. Try lengthening the nose gear in order to increase the angle of attack in the plane's 10:38 static position.
Good luck Julius!
Mr J this one is a work of art. Hopefully you found the solution 👍
I hope so too
It looks to me like the horizontal stabilizer is too small. When you scale a full-scale airplane down, you need to enlarge the horizontal and vertical stabilizers. This is due to what’s referred to as Reynolds numbers. Basically, it’s because of the density of the air. On a model plane, the horizontal stabilizer should have about 20% of the area of the wing. So if the wing is 500 sq-in, the stab should be 100 sq-in. Also, the smaller the horizontal stabilizer is, the further forward the CG needs to be. With a small stab, the CG might need to be at 20%. I would never test fly a plane with the CG further back than 25%. And, if the control surfaces move too far, move the pushrod out on the control horn and in on the servo arm. When you decrease the travel in your transmitter, you decrease the resolution and accuracy of the control surfaces.
Horizontal Stab 0 grades incidence.
Wing 1.5 grades of incidence.
Angle of incidence of wing should be 5 degrees and motors the same. horizontal Stabilizer should be maybe 3 degrees. You need a better way to join the wings so they have a bit of polyhedral and are stronger. Wooden dowel works fine. CG close to 25 % of center of lift. As an rc hobbyist and designer, I am not insulting , just hoping to help. I have built a 2 meter pby with retracting wheels and floats and counter rotating props. Had to use a 10 channel receiver for gps RTH, retractable wheels or retractable floats as wanted. Complex build but works.
You need up thrust on motors like full scale because thrust angle is way above cg. Try 1 degree up thrust
I ThAnkyou for your videos they are helpful and full of information your skills are amazing
force x arm = moment
the longer the tail is, the more sensitive it to the controls
good job brother....keep up ...
Great flight learning notes , Waiting for next video
That sure is a great looking recreation of that plain
keren om sayang lupa setting servo travel masih kebesaran😁 yg A-10 juga tu om, kalau saya jet model miden servo travel semua saya kecilin untuk amannya expo saya 20% 😁
semuanya yang saya sebut di video salah om, nanti saya gedein lagi travelnya, malah bahaya kalo ratenya kecil. Ternyata salah di sudut motor, harusnya up thrust saya malah di down thrust hehehe
Can you do maybe the gloster meteor next?
Om yg nerbangin, saya yg deg2an wkwk
Love the build and really enjoy your videos
Awesome, thank you!
i'd like to see the entire construction of how you built this plane in your next video or so
Will do
I salute your honesty
Hi Julius, do you know where can we use Ppaer replika again? THANKS
maybe next week, I will put it back online, it will not complete but at least you have some of the models accessible while I finish uploading the rest of it day by day until it complete
@@JuliusPerdana Thank you for all this work, and all my support! I hope see your page online soon :)
Keren om, mantap
Beautiful plane. You may want to have an experienced pilot make the first flights for you,.
Well I think Julius Perdana did an impressive job to keep the plane in the air. Some crazy idea: could it help to make the propellers spin in the other direction? At the moment, one is CW and the other CCW, but exchange this.
Your thrust angle is backwards due to the fact it's a pusher prop configuration ,add upward thrust not down
yes you are correct, it should be up thrust not down thrust.
Are you intending to release this model at some point ? Many thanks Julius 🙏
yes off course
جميل
What flight controller did you use for this plane?
no flight controller, just gyro flight stabilizer on the aileron.
Nu saena
It's a beautiful beautiful aircraft Juli..that's why I commented on Props for it as my dynam needed bigger props but clearance wouldn't allow it after sering this I believe now Props we're that size for a reason....This looks like 1200mm props from Spitfire..Fantastic..Good handling..center if grav OK ctr if pressure may need tackling brotherman..Outstanding Effort 👌 with fine tuning will be best yet..congratulations.
semoga di balas 🙏, Mohon Bantuannya Pak , saya membuat pesawat rc lavockhin La-7 , saat uji coba menerbangkannya kenapa ya pesawat saya saat di terbangkan badan pesawat tidak langsung lurus sejajar tetapi malah kepala pesawatnya saja yg kerangkat sedangkan ekor pesawatnya turun seperti payung mohon di bantu 🙏🙏🙏
mungkin tail heavy, ga liat langsung jadi cuma bisa nebak
Cara mengatasinya pak gimana 🙏
Seems like the motor down angle would hold it on ground? Slight up angle of motors? Also wings kinda droop, do they need small amount of dihedral? Beautiful cat and amazing saves! Also the pitch up could be because elevator is blocked by wing?
yes you are correct, it should be up thrust not down thrust. It was actually pitch down tendency not pitch up, I was a bit confused at that time.
@@JuliusPerdana I hope you get it sorted out. Lovely model! A flying boat would need more motor up angle to help full the hull free of the water. Good luck!
Breathtaking flying ! I thought it would jump off the ground . Big surprise !
Awesome work. Looks great 👌😎
Thanks 👍
Sorry I re read your post mortem it,s pitching up under power so more up on the motors isn,t the answer must be in the rigging angles main wing / horizontal stabiliser?
At first I thought that way, but after I watch the video over and over again. It's actually pitch DOWN if I use power
@@JuliusPerdana Up thrust might well be the answer. Good Luck
Can you please share the full long videos as always?
later when all worked well in land and water
Have you thought about raising both ailerons that should counter your wingtip washout?
TWO MOTOR IS TERN THE SAME WAI? BOUTH TERN LEFT OR RIGHT! NOT DIEFRENT AI THINK!
counter rotation with inward rotation