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Help! TinyTrainer build

#1
First off I know that I am pushing this airframe too hard and am running a little heavy. My latest desire is putting landing gear on my TT. What I had on hand was a spare bracket for my apprentice with thin 1.5 inch wheels with an 800mah 3s. The first flight folded the wing at the center due to the thin spars not holding. I fixed this by joining the two center spars on either side of a bbq skewer. The second flight was met with the wing snapping at the servo cutouts.

I’m thinking of using a skewer taped down with fiber mesh packing tape but before I sacrifice my newly built nose/power pod, what have others tried that worked?
 

Hai-Lee

Old and Bold RC PILOT
Mentor
#2
First off I know that I am pushing this airframe too hard and am running a little heavy. My latest desire is putting landing gear on my TT. What I had on hand was a spare bracket for my apprentice with thin 1.5 inch wheels with an 800mah 3s. The first flight folded the wing at the center due to the thin spars not holding. I fixed this by joining the two center spars on either side of a bbq skewer. The second flight was met with the wing snapping at the servo cutouts.

I’m thinking of using a skewer taped down with fiber mesh packing tape but before I sacrifice my newly built nose/power pod, what have others tried that worked?
Firstly you do not mention if you are using a FT supplied kit or if you are scratch building. If you are one who cuts out their own pieces you could try a different and higher lift wing for the TT such as can be found here: https://forum.flitetest.com/index.php?threads/my-mutts.57768/
That wing was designed with much higher lift in mind!
If you wish to use the original design wing the first thing I would recommend is that you change the spar from a flat piece of FB to a couple of vertically fitted, (paper on the spar runs from top of wing to bottom) this improves wing rigidity. In addition I would fit a piece of paddle pop stick on the underside of the wing LE centrally so that the wing incidence angle is increased or the front of the wing sits a little higher for a little more lift.

As for the normal wing snapping you could bury a few lengths of BBQ skewer in the wing LE fold.

With every beginner wing I build I run cloth reinforced tape along the wing LE as this tends to allow the wing LE to crease without tearing in most impacts, (including poles and fences).

The servo cutouts do not need to be made and the servos do not need to be fitted exactly where the original design recommended. You can fit the servos at the outer edge of the wing bottom panel and use servo extension leads to extend the servos so the leads still exit the wing at the central hole in the wing underside. Best done with an alternate Spar of course!

The wing joint will not support a very heavy TT long term and it will fail eventually. I recommend that you cut down a paddle pop stick and use it as a dihedral brace or perhaps two.

With the landing gear you can fit almost anything with weight being the only real issue to be concerned about!

For your perusal the following link will give you a list of mods or changes to the TT where you can find what others have done to overcome various issues with the TT. https://forum.flitetest.com/index.php?threads/tiny-trainer-modifications-list.57794/

If you want further info just post your questions!

Have fun!
 
#3
Good points, thanks for that. I cut these from DTFB and lift is no problem, it climbs on its own quite well although that would definitely be more rigid. With that mod I probably wouldn’t be able to get the proper dihedral?

I’m saving my speed build kit for when I come up with something that flies as I would expect. If I’m using the DTFB is there a difference in rigidity?

I can take some pictures of the carnage when I get home but the fold appears to start more to the trailing edge as the paper wasn’t even ripped near the leading edge. My ignorance could be the factor however. Just trying to learn. It was a great plane until I tried to modify it 😁
 
#6
My solution, uses a smaller version of the scout gear design, slotted into the doubles section of fuselage 1/4” ahead of the oval cut out. Uses 55mm ish wheels.
View attachment 127329
Still on my original FT wing. Runs vertical on 2s with an 1806 2400kv motor and 6x4 prop.
That’s probably another part of my weight/speed contribution to the folding. I was running a 2212 2400kv with a 6/3 prop. Barely needed a quarter throttle for level flight.

Didn’t have chance for pictures last night, will hit it tonight.

@kilroy07 i did buy one of those gliders to tool with for the kids lol
 

Hai-Lee

Old and Bold RC PILOT
Mentor
#8
I recently folded two sports wings.
Build the MUTTS wing with the same spar height as the original TT wing and try to fold that!
Use the MUTTS aileron position, (do not need the flaps), and fit a dihedral brace if needed or a paddle pop stick as a brace if no dihedral required.

The difference will surprise you!

Have fun!
 

mayan

Well-known member
#9
Build the MUTTS wing with the same spar height as the original TT wing and try to fold that!
Use the MUTTS aileron position, (do not need the flaps), and fit a dihedral brace if needed or a paddle pop stick as a brace if no dihedral required.

The difference will surprise you!

Have fun!
I might just have to give it a try on my next TT build :).