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Building Hai-Lee's Tiny Trainer Slow Wing

#1
Hi everybody,

I decided to build the slowing modification that Hai-Lee posted here: Looking for a slow, Park flyer FT build and figured I would catalog my experiences and share them, since this is the first time I've gone outside the bounds of the "standard" FT plans.

Started with the PDF that Hai-Lee posted, just using the tip plans, and attached them to posterboard like SP0NZ described in an article:

IMG_7560.JPG

I only used the tip plans, and made the center section by using the inner end of the tip plan and drawing those lines all the way across a sheet of foamboard. It was pretty easy to make, but was hilariously long, at least given the scale of the Tiny Trainer:

IMG_7559.JPG

Next, for electronics, I used the following:
  • Racerstar BR2212 1400kV motor
  • 8x4.3 Props
  • EMAX BLHeli 30A ESC (plus a XT60 to XT30 adapter to work with my small battery)
  • FlySky FS-IA6B receiver
  • EMAX 6g servos
  • 800mAh 2S lipo

The fuselage is pretty much a stock Tiny Trainer, except that the motor sticks out a bit, and the shaft sticks out even further:

IMG_7995.JPG

As a result, the CG is off (which you'll see in the video below). So, I moved the battery back and added tail weight (those lead sticker things):

IMG_7996.JPG

Here's the whole thing hanging on my wall:

IMG_7982.JPG

I haven't yet built landing gear, though I probably should. Here's a video of my maiden flight(s). I was alone, so the plane gets pretty small in the wide field of view, but it hopefully gets the idea across:


Things I want to try:
  • Put a 3S battery on it and remove tail weight, then reduce the max throttle to compensate for the battery, just to see how that changes things
  • Figure out a way to either reduce the throws at higher throttle (that thing is *super* sensitive at non-cruising throttle, as you can see from my first takeoff)
  • Figure out a way to compensate further for the higher torque of the bigger prop. It was noticeably easier to turn left than right. The motor is angled at the stock TT angle.
  • Fly a lot more and see just how slow I can get it :)

I've had fun with the project so far. It's a good learning experience.
 

Hai-Lee

Old and Bold RC PILOT
#3
Thank you for the build and video as I could not produce the visual info most require.

There is one thing you can play with to calm the climb on throttle nature of the wing and that is to reduce its incidence slightly by adding some thin packing under the rear of the wing. Secondly increase the downthrust slightly.

I have even been experimenting with SLAB type flaps attached to the wing TE for even slower flight but then the effort does not decrease the landing speed much as the drag is extreme and you need throttle to have a nice controlled landing.

As for being calming I started to develop a bad habit when flying mine at great height and that was I would look away and become easily distracted. Whilst this plane/wing combination is easy to locate as it stays very close to where you left it, but when flying other designs to look away to invite disaster, (and it did visit quite often!).

Thanks again you do good work!
 
#4
Thanks for the feedback! I'll give those ideas a try. I'd like to try this out as a trainer for my daughter, but currently given the control sensitivity, the normal trainer wing will probably work better.

Do you have any intuition about the effect of removing tail weight and moving the battery further back? I used the same CG position as the trainer wing, and I think maybe I had the CG too far back. I guess I'll keep playing with it. Probably just need to do a bunch of takeoffs and landings to try it out. Cruising is fine, but "transitions" are trouble. :)
 

jamboree1

Active member
#5
I have a few things I noticed i wanted to point out. First off is the prop adapter to motor shaft, is that thing on all the way? It seems to look like it's sticking out exceedingly far. Second, you can always relocate the power pod back further. Third, that motor is a bit large for that model, but it will work. I really like Hai Lee's wing design.
 

Hai-Lee

Old and Bold RC PILOT
#6
Thanks for the feedback! I'll give those ideas a try. I'd like to try this out as a trainer for my daughter, but currently given the control sensitivity, the normal trainer wing will probably work better.

Do you have any intuition about the effect of removing tail weight and moving the battery further back? I used the same CG position as the trainer wing, and I think maybe I had the CG too far back. I guess I'll keep playing with it. Probably just need to do a bunch of takeoffs and landings to try it out. Cruising is fine, but "transitions" are trouble. :)
Firstly a bit of history! I found the the original wing especially the polyhedral is awesome, Unfortunately with a heavier FB here the speed was a little high and the tail moment a little short so a heavy handed newbie could easily tree it or just porpoise it all across the sky.

The wing allowed the speed issue to be eliminated but the short tail moment issue remained, A short tail moment, (distance between the wing and tail) means that the tail has less mass to move or accelerate to shift the tail up or down and therefore far more sensitive or agile. Another way to look at it is the tail only needs to move a short distance up or down but if it is twice the distance away it must move 2 times the distance for the same pitch change.

For my trainees I have dual rated set for minimal throw on the elevator especially and when they can handle that, (and have learned that the sticks have many valid positions and they are not switches), I teach them the idea of fine control and gentle control movements on full rate.

I do love the extreme agility that the large wing with standard control deflections and when it loops at full power it can almost do it in 2 to 3 times its own length, (and occasionally air launch its battery) :rolleyes:. Anyway calming the elevator and rudder can be done with massive control throw reductions, (dual rates), or by increasing the tail moment by either making a longer fuselage rear section or making an extension piece to allow the tail to be further from the rear of the wing. DO not just dial down the deflections on the TX but adjust the throws on the control horns and the servo output arms.

You do not need to worry about having enough rudder for stability because the wing design just wants to fly straight and level but extreme hardover rudder can cause Dutch roll. Just another trick for a super-newbie is to adjust the throttle on the TX if possible and dial down the max to a moderate cruise.

Making the tail longer will automatically shift the Bare fuselage/wing CG rearwards and so to maintain the proper CG you can start moving battery etc to the front or even inside the Fuselage. With enough FB behind the CG you won't need tail weights.
 
#7
I have a few things I noticed i wanted to point out. First off is the prop adapter to motor shaft, is that thing on all the way? It seems to look like it's sticking out exceedingly far. Second, you can always relocate the power pod back further. Third, that motor is a bit large for that model, but it will work. I really like Hai Lee's wing design.
Thanks for the feedback!

Re prop adapter, yes. It's on all the way. It's a cheapo Racerstar and the prop adapter that came with it didn't even fit! So I bought one that fit and this is how it sits. I bought some prop savers too, since that would shorten up the shaft, but the ones I bought didn't fit either.

I'll look at moving the power pod back. I may not be able to move it back very far, since the motor is angled a bit per the original TT angle.

I agree about the size of the motor. I looked for something that would yield approximately the kV that Hai-Lee originally mentioned (1400).

I like the design too. Once I get the hang of it I imagine it will look quite graceful in the air.
 
#8
Firstly a bit of history! I found the the original wing especially the polyhedral is awesome, Unfortunately with a heavier FB here the speed was a little high and the tail moment a little short so a heavy handed newbie could easily tree it or just porpoise it all across the sky.

<snip lots of good info>

Making the tail longer will automatically shift the Bare fuselage/wing CG rearwards and so to maintain the proper CG you can start moving battery etc to the front or even inside the Fuselage. With enough FB behind the CG you won't need tail weights.
Thanks, Hai-Lee. I think what I'm going to try for now is teaching myself to fly it less like a heavy-handed newbie (which is pretty much what I am), but also crank down on the throws to see if I can make it easier for my daughter to learn on. Also, the servo arms I'm using have 3 holes, and I'm in the middle one, so I'll move the push rod to the innermost one to start with. Keeping things the way they are would force me to lighten up my touch, which could be good, though.

Potentially dumb question: What is "FB"?

Thanks!
 

Hai-Lee

Old and Bold RC PILOT
#9
FB is proof that I am getting old and typing the word Foamboard so often on these threads is a lot of keystrokes. So I just use FB to indicate the word Foaamboard.
 
#10
FB is proof that I am getting old and typing the word Foamboard so often on these threads is a lot of keystrokes. So I just use FB to indicate the word Foaamboard.
Thanks for the clarification. I can imagine it would get tiring eventually. And thanks for all the information, too.
 
#11
Quick update: I don't have any footage or photos, but I flew the airplane again a couple days ago without any mods. I must've internalized everyone's feedback, because I had a *very* enjoyable flight (only had time for 1 battery). I let the airframe do most of the work and minimized my inputs as much as possible. It launched like an arrow. A rather slow arrow. I also made sure to make very wide turns (minimizing input) and didn't have any roll problems.

It was quite graceful looking in the air when I flew it this way.

I think I'm going to leave it as-is. I may try to put a 2200mAh 3S on it to see how it performs a little heavier. Also to see how long of a flight time I can get, since I'm currently using a 300mAh 3S.