Guillow Piper Cub RC Conversion Part 2

[@marcobontag]

Hi Tim, at first the same thing happened to me in the two Guillow Super Cubs that I converted to RC. What solved the problems and I think yours may be missing are two things: first a bit of washout angle to avoid tip stall. You have to twist the wings a little so that the leading edge at the tip is one or two degrees lower than in the central area. The actual Super Cub has too. Second, I think that the horizontal stabilizer in this kit has a low angle of incidence which pushes the tail down, which added to the high lift of the wing that causes a stall as it picks up speed. I corrected it by modifying the stabilizer angle. I hope this helps. Greetings.

[@marcobontag]

I also built both with ailerons, they help when the wing drops but they generate a lot of adverse yaw.

[@TimMcKay56]

Marco: Very useful tips, thanks! Copy on adverse yaw as well. Tim

[@erikhilsinger9421]

I second this. Move the CG forward a bit, washout the wingtips a smidge, and check the horizontal stabilizer angle of incidence. Glide test to see if it stalls with no power applied to get a baseline. I think it is super close to being as good as the Aeronca but it sure seems like the combination of scale-like looks and small size raises the stakes a lot. Nice work on the planes and the videos!

[@HD-su9sq]

I think Marco has nailed it. The wing drop is caused by the tip (or whole wing) stalling first and the classic remedy is to have washout. Also the Cub seems to fly tail low, and I agree with Marco that the tail plane is the problem. I love the channel and your handiwork!

[@TimMcKay56]

HD: Many thanks for your input! Tim

[@CliffHarveyRCPlanes]

Tim, I think I would try even more noseweight and if that didn't improve matters add some dihedral? The Hellcat is a nice flyer, I managed to get my Guillow's Spitfire flying very nicely as well.

[@TimMcKay56]

Cliff: Adding dihedral could help, but I am getting more and more intrigued with my designs that fly with absolutely zero dihedral, as well as a flat wing. Tim

[@capitanpitirre3409]

Hi Mr. McKay, I saw your video on the J3 rc conversion, and I would like to add some thoughts for your consideration. In the video after you double checked the cg, and flatness of the wing panel. I think, if you have not tried it by now. Check the overall incidence. In the 1st video you mentioned that you would cut the side window/wingsaddle area to include a few degrees of positive incidence. In my observation as a full scale aviator myself, I think that would be the cause of your sudden left wing panel drop, left spin entry tendency that the model showed. Let me explain, in a nutshell my observation. The main cause of spins in full scale aircraft is first, uncoordinated flight followed by one wing stalling before the other. That means, if the designer all ready added the maximum positive incidence to the wing root, adding some more will exacerbate the possibility of an earlier stall. Add to this the P-factor, and possible strong torque the motor is adding to this light air frame. Then just a little rudder into the stalled tip and result, incipient spin entry which you expertly recover from by looking at the sudden snap and nose high pitch recovery. Also in the first launch where the model passes in front of the camera, the plane seems to be in skidding flight path (nose pointing left while still flying wings level). Add to it that by having the wing perfectly flat, you are not including some negative incidence in relation to the wing root at the tips. If you look at single engine Cessnas, Pipers these have wing tip stall reducers such as washout/twist or spanwise airfoil distribution (thinner airfoil cross sections at the root increasing in thickness towards the tips (piper cherokee line) Perhaps to start off, place a shim behind the trailing edge of the wing. and see the result. Also, try to add maybe 1-3 degrees of twist at both tip trailing edges so that the tips have a negative incidence in relation to the root, and also consider the overall ballance of the wing alone. Please let me know how it works. Thanks for your great videos! Looking forward to also get deeper into the hobby after my retirement. Take care. Rafael E. Morales, PR, USA

[@TimMcKay56]

Rafael: Many thanks for checking in! All good points on the Guillow kit. I have found, over my conversion of 8 Guillow kits, is that very small errors can creep into the wing, fuselage alignment, etc. that have a quite large impact on flight handling characteristics, especially with the smaller scale models. I wish I had a better understanding of this, but this seems to be the way things work out. Some fly great, others not so much. Tim

[@perrylopez7784]

Hi Tim, beautiful planes. I hope that you fix the piper soon. Thanks for another great video.

[@TimMcKay56]

Perry: Thanks for the feedback. I am done with the Cub mods, on to other projects! 😁 Tim

[@wackaircaftmechanic2312]

Nice video! It's good to not give up. Thanks for sharing

[@TimMcKay56]

RS: Thanks for watching! Tim

[@chilarai1]

Another masterclass. Thank you Tim.

[@TimMcKay56]

Chilarai: Many thanks for checking in! Tim

[@d.r.4453]

You build such beautiful aircraft. They look amazing and quite realistic in flight. Personally I like the slower and lower lying models like your Aeronca. I'm not much into fast flying models. I may take a stab at building the Aeronca myself. Awesome work.

[@TimMcKay56]

DR: Appreciate your feedback, and good luck with your build! Tim

[@demietrilazarakis283]

Nice looking plane! I have one that flies quite well. You might eat to add a little washout, that helped mine allot.

[@TimMcKay56]

Demietri: Roger that on wing washout, fully agree! Tim

[@planker]

Looking Good. My first kit build was a Guillow's Hawker. I built almost all but the lager kits. Gentel hand tosses (no power) to set trim. I see you have nice grass to do this. Elec or rubber, Hand toss will get you in the ball park. All Guillows are tail heavy at first, The lump of clay is an indicator. If the plans show the gas or control line mods, there are considerations, The empennage could be solid balsa.

[@TimMcKay56]

Planker: Good inputs, thanks! Tim

[@tonymccarthy9273]

Hi Tim , I just noticed on your piper cub, that the rudder is almost half size of the fin , I wonder if you could make the rudder smaller , I have a model that has a tiny rudder , and it turns it adequately, just hope that can help, and my model is a high wing model like a trainer , with dihedral, from Tony, from england

[@TimMcKay56]

Tony: Yes, you can make the rudder smaller. As the model flies slowly, I opted for a larger rudder to ensure needed control. Tim

[@davidquerry8869]

Thanks for the downs, also Tim. Let's us know we are not alone. I had a Clancy Baby Bee once. I'll be darned if I could get that squirrel to fly consistently.

[@TimMcKay56]

David: Fully agree. Sometimes, for whatever reason (especially with the smaller models), something happened and they just do not want to fly right. Tim

[@rodneytrynor7374]

If the wing isn't square with the fuselage(where the wing connects to the cabin) cause the piper cub to fly into a spin like that even though the wing itself isn't warped? Just a thought.

[@TimMcKay56]

Rodney: Appreciate the input, but I do think the wing is mounted square. Tim

[@randall4411]

I'm interested to see why the Cub turns in like that . Wing incidence ? That caused me problems on my free fight planes .

[@TimMcKay56]

Randall: I think the incidence is OK, a bit positive like on my other Guillow RC models. Tim

[@sonnymoorehouse1941]

could it be a fault with the RC control module ?

[@TimMcKay56]

Sonny: I am quite sure the RC electronics are OK. Tim

[@sonnymoorehouse1941]

@@TimMcKay56 Thank you for sharing your builds !!!!! enjoy your videos very much

[@TimMcKay56]

Thanks! Tim

[@rperry70]

I know this is an old video, and I agree with the washout solution. Also, I think you could use more dihedral. Rudder only models really benefit from this when you have no direct control of the roll.

[@TimMcKay56]

Good points!

[@jasonparker11]

It’s dropping one wing and hardly turning the other way, id check that one wing isn’t heavier than the other, I’ve had planes do the same thing and had to add weight on the opposite wing to get them to fly level

[@TimMcKay56]

JP: Great tip, thanks! Tim

[@stevendegiorgio3143]

Maybe for the cub try removing the positive incidence on the wing.

[@TimMcKay56]

Steven: Sounds like that is worth a try, many thanks! Tim

[@zacrulesrc7687]

I had the exact same results with this kit, I had ailerons but it would still spin over

[@TimMcKay56]

Zac: Very interesting, thanks for sharing. Tim

[@Glicksman1]

As I see it,, this one flies just like a Guillows airplane. The larger ones fly a little better as you have demonstrated, but that tiny unmodified Cub will always either be tail heavy unless heavily nose- weight, or unless the centre of gravity is moved rearward, making it a stall/spin waiting to happen. Guillows kits, if unmodified and built from the box, have poor airfoils and too much wing loading to fly well. Given your flight results, I think that the center of lift and center of gravity are too close, a common problem with Guillows' suff. Build Dumas kits, they actually fly well without much or any mods. I learned not to expect these kits to be good flyers many decades ago. You are a valiant warrior, though, and if anyone can make them fly well, you can.

[@TimMcKay56]

Glicksman: Kind words and thanks for checking in!! Tim

[@Glicksman1]

@@TimMcKay56 No worries, mate.

[@rva1945]

Just try to increase dihedral. It's a 3-channel model.

[@TimMcKay56]

👍🏻 Tim

[@jimzeleny7213]

I built a small model powered by an AME 0.060. I was going to name it "feather" trying to keep it light. It was three channel with engine rudder and elevator. Long story short it would not turn!. I figured it was insufficient dihedral for a three channel plane.

[@TimMcKay56]

Jim: Is a fun hobby! Tim

[@trackie1957]

The very last second of flight of the Hellcat made me cringe! I hope it survived because it looked great in the air!

[@TimMcKay56]

Trackie: The landings were not elegant, tried for the grass as much as possible. Hellcat doing fine! Tim

[@altamirofaria5741]

👍🇧🇷🇧🇷🇧🇷 Abraço

[@TimMcKay56]

Thanks! Tim

[@Allen46u5k]

Real Cubs have washout in the wing, check a real Cub out.

[@TimMcKay56]

Great point, will check this out! Tim