Full length spar in Tiny Trainer aileron wing.

[ingannilo]

Hi all,

I built a tiny trainer slowly through August. Over this last week I've really enjoyed flying it. But with only about a dozen flights (some pretty spirited), the wing has started to bend right at the servo, giving me "one sided polyhedral". I built the plane with basswood inner spars and balsa outer spars, following the foam patterns.

What I want to know is if anyone has thought of a slight redesign to the aileron wing for the TT which allows for a full-length spar, or a spar that doesn't have a break in it at the servos. Maybe just more clever way to mount the aileron servos, or some other, smaller spars running around the servos (I'm considering running two carbon rods around the servos and CAing those to the existing spars.

Anyway, just curious.

 

[Hai-Lee]

On my latest version, (I build and gift a number each year), I do fit a full length spar of the standard style.

I just use HK 3.7gram servos which dosit a little proud of the wing lower surface but not too bad. They do not effect the flight.

Earlier I used a few paddle-pop sticks on the inside of the wing around the Servo Gap and that seemed to work also.

Even earlier I tried a perfectly flat "One piece" wing with full width ailerons and the servos fitted in the wing tips. It flew well also but was not as stable as the original of course.

FT designs are something that will fly reasonably well but that does not mean you should not experiment. I believe that FT encourages us all to experiment and get out of the sport/hobby as much as you can.

 

[Austin]

I built my Aileron wing the normal way with foam spars and then ran a 1/4" wood rod(not sure what kind of wood, the tag said hardwood) down the whole wing on the leading edge side of my spar. The rod could flex and didn't seem to mess with the dihedral much. I can post a pic if you like. I put the rod thru after i built the wing to fix it from folding on pulling out of dives. Worked really good for me

 

[kdobson83]

What kind of flying are you guys doing that requires wood spars in your Tiny Trainer wing? Lmao My Trainer is built to spec with a 2204 emax motor, 3 cell 800mah battery and a 6045 prop, full speed dive and pulling up does nothing to my wing. My suggestion would be to upgrade planes. Lol

 

[Hai-Lee]

What kind of flying are you guys doing that requires wood spars in your Tiny Trainer wing? Lmao My Trainer is built to spec with a 2204 emax motor, 3 cell 800mah battery and a 6045 prop, full speed dive and pulling up does nothing to my wing. My suggestion would be to upgrade planes. Lol

SNAP!! (Well almost). I run 2205C 1400Kv motors from HK with an 850mA 3S battery and either a 6x4.5 or a 6x5 prop.

My changes were brought about by 2 different requirements. The first requirement was to reduce damage to crash landings by newbie pilots under training and the second was because I live in a sub-tropical environment there is considerable moisture absorbed by the paper in the foam board over time.

As for your full speed and pull up "been there and done that" standard wing survives quite well. Occasionally the battery bails out and that makes landing a little difficult but otherwise the original design is sound.

 

[ingannilo]

Hai-Lee: I built this wing totally flat, like your one design; I was looking for a very responsive plane, something like a foam version of Wild Fred's (of TheProfileBrotherhood) Ferroplane. I like the pop-sickle stick idea, but I'm torn between that and the full length single piece with smaller servos. How proud of the wing do the 3.7 gram units sit? How itsy-bitsy are the holes in the servo arms? I had a real bear of a time getting linkage stoppers into the 5 gram servo's horn. Has one of these designs been more successful than the others? It's awesome that you guys have been fiddling with these designs.

kdobston83: I live in a very humid (north-central Florida) environment, so the foam loses a lot of rigidity. I'm not running crazy gear in the TT: 5 gram servos, 800mAh 3S batteries, 12amp Hobbywing Flyfun ESC, an "Multistar V-Spec"1808 2400kv motor, and 6x5 APC prop. I don't think my flying is very aggressive, certainly compared to some of the stuff I've seen Fred's Ferroplane do it isn't. But the weather here just dooms DTFB planes to docility unless you beef 'em up quite a bit.

 

[Craftydan]

I had a real bear of a time getting linkage stoppers into the 5 gram servo's horn.

You can always mount the linkage stoppers in the control horn instead. Avoids the whole problem of over-drilling the tiny servo horns.

 

[kdobson83]

Well, humidity does change things slightly. Why not try water proofing it with tape like the experimental airlines guy on YouTube does, or just straight clear packing tape. Or, try the water resistant foam FliteTest just released. Any of these would fix your humidity issues.

As far as training noobs to fly it and resisting lots of crashes and hard landings, I think you are on the right path, adding wood or carbon to it will do the trick. But adding a covering of tape will help a whole bunch too. Ive found that my one plane I have wrapped in clear packing tape can withstand a whole bunch more beating than without. (RIP FT Mini Mustang)

Anyway, good luck fellas. Happy flying to you.

 

[J Bergsmith]

Go to Walmart and get some carbon fiber arrows and install as wing spars. Problem solved, light weight, low cost.

 

[Hai-Lee]

How proud of the wing do the 3.7 gram units sit? How itsy-bitsy are the holes in the servo arms? I had a real bear of a time getting linkage stoppers into the 5 gram servo's horn.

kdobston83: I live in a very humid (north-central Florida) environment, so the foam loses a lot of rigidity. But the weather here just dooms DTFB planes to docility unless you beef 'em up quite a bit.

The servos prrotrude into the slip stream by about 1mm. I do not fit my linkage stoppers on the servo end but rather drill holes in the control horns as recommended by Crafty Dan. For water purposes I cover the exposed servo with a single layer of Packing tape or I trim the unused portion of the servo horn and cover the whole servo with a small teardrop shaped piece of clear plastic similar to those used in blister packaging. I glue and tape the blister in place with a small hole for the pushrod of course.

Two simple things you can try to reduce humidity damage to the internal surfaces of the FB is to either coat the FB with a thin layer of paint or even glue.

The second thing I discovered by accident was to use the "peanut" shaped Paddle pop sticks, (trimmed down), as dihedral braces they fit and work fantastically.

The taped outer surface is a given! Also a layer of paint or glue around all the exposed edges and the hinge lines completes the deal.

Often after an early morning flight at my field especially when the grass is due to be mowed the plane actually drips water including from inside the open ends of the wing all caused by heavy dew.

My current TT has over 50 hours flight time and has endured all sorts of landing attitudes and soldiers on without any repairs apart from a new powerpod or two. OHHH I should also include about a dozen or so props as well

Try fitting a simple "Knock off" landing gear it increases the use and the fun for the TT in that I use it for those trying to learn take offs, touch and goes, and landings. My landing gear is simple bent wire held in place with a single layer of packing tape.

Enjoy!!!

 

[ingannilo]

Thanks to everybody for their advice. I do tape the outside of my DTFB planes where's it's easy to tape neatly; the fuse is all taped up, as are the leading edges of the wing and stabilizers, and on most of the open edges where humidity/water can make the paper peel back. Today I added more tape, covering the outside of the wing. Also following J Bergsmith's suggestion, I rammed a cheap CF arrow from WalMart through the gap between the spar and the leading edge of my wing. It did a great job at fixing my one-sided polyhedral.

I flew a few packs at the park this evening, and it performed wonderfully. I'll build a new wing soon with the tips from this thread integrated from the start. Pictures and details to come.

 

[Hai-Lee]

Thanks to everybody for their advice. I do tape the outside of my DTFB planes where's it's easy to tape neatly; the fuse is all taped up, as are the leading edges of the wing and stabilizers, and on most of the open edges where humidity/water can make the paper peel back. Today I added more tape, covering the outside of the wing.

I look forward to the post.

As for the tape I normally tape after I cut it out but before I clean out the channels for folding and gluing.

When assembled and glued I then run a line of clear packing tape over the exposed joints, (Those not taped over).

For wings and tails where they are glued in I do not tape over the area to be glued of course.

The tape should be pressed into the FB to get best adhesion. I rub the tape with the curved handle of a pair of scissors.

Just a little extra info for you to think about.

If you are likely to encounter trees, mid air collisions or landing obstacles you can beef up the LE of the wing with a piece of the FLAT CF inserted into the fold before gluing.

Finally Should you wish to build a TT wing without the expense of an arrow shaft or similar you could just build the wing spar out of multiple 5mm strips of FB with the paper running vertical or perpendicular to the wing surface. As the paper layers of the laminated spar are mostly never in contact with the air there is no weakening and also the FB is much more resistant to crushing in this manner. This gives a slightly heavier and far stronger spar with no moisture issues. Unfortunately the Hot Melt glue is not highly suited to this method and so a craft glue or white glue will be required to make the spar.

I await you final result!!:black_eyed:

 

[dhoppe74]

Hai-Lee: I built this wing totally flat, like your one design; I was looking for a very responsive plane, something like a foam version of Wild Fred's (of TheProfileBrotherhood) Ferroplane. I like the pop-sickle stick idea, but I'm torn between that and the full length single piece with smaller servos. How proud of the wing do the 3.7 gram units sit? How itsy-bitsy are the holes in the servo arms? I had a real bear of a time getting linkage stoppers into the 5 gram servo's horn. Has one of these designs been more successful than the others? It's awesome that you guys have been fiddling with these designs.

kdobston83: I live in a very humid (north-central Florida) environment, so the foam loses a lot of rigidity. I'm not running crazy gear in the TT: 5 gram servos, 800mAh 3S batteries, 12amp Hobbywing Flyfun ESC, an "Multistar V-Spec"1808 2400kv motor, and 6x5 APC prop. I don't think my flying is very aggressive, certainly compared to some of the stuff I've seen Fred's Ferroplane do it isn't. But the weather here just dooms DTFB planes to docility unless you beef 'em up quite a bit.

Out of curiousity...... I just ordered a few of thos vspec 1808-2400 motors to use on some of the FT mini planes, but I'm having trouble finding mounts for them. What did you use for motor mounts and where might I be able to find them? Any help would be greatly appreciated!

 

[FDS]

You can use the 3d printed firewalls for 12mm hole spacing or make your own ply ones from modelling ply wood. You can cut a lot out at once then drill them using a simple template. Modelling ply can be cut with a Stanley knife and steel rule.
I am assuming you have the 1808’s with 12mm holes not the Hobbyking ones with 12 and 16mm holes, as those fit the standard FT firewall without mods.

 

[Brickman]

The wing seems the strongest part of my Tiny Trainer. Gone through a few fuselage though. Even went full throttle into a tree. The wing was fine. I have a trainer wing but dont use it. I like the sport wing better. Its a fun plane and I find myself flying it more than my others. I dont know why but it is the only one im comfortable hand launching.