150% Un-Tiny Trainer Build

[duckduckgoose]

Battery tray coming along, now just waiting for plywood to bend into shape and dry. I made a small error and it looks like the 3000mah battery is too big to fit in the tray, but it fits my 1300 mAh perfect. I might just add ballast weight in the tray to make up the weight difference. All the plywood should help add some nose weight.

 

[duckduckgoose]

Maiden! I ended up ditching the above battery tray, after all that, I realised the battery wouldn't fit between the power pod and the bottom of the fuselage. Anyway I added yet more plywood this time to the back of the wing to help the strengthen it where the rubber bands wrap around. AUW is now 1.15kg. Flight was awesome, plenty of power (I never even went about 1/2 throttle). Thanks to the thick box spar it has great slow flying characteristics and can fly very slowly, which is mainly what I did, around and around. No flips or rolls but I am certain it would be capable, I was just terrified of doing something stupid. See, I am not very good at LOS flying, I seem to struggle a lot with orientation, and I don't trust my brain enough. I know I just need practice but with these larger planes I much prefer fpv. Going to throw on the fpv and go up high next chance I get, which is definitely what it wanted to do. Landing was very pleasant it came in super slow and landed in a patch of soft(ish) grass. I get the feeling, flaperons would work well with this one. Video coming soon, for now here's a screenshot.

 

[duckduckgoose]

Here's the video. There was a light breeze which let it just sit almost still. This might even be a nice sloper, although I have no slopes around to find out haha. Sorry for the weird blipping noises, I had to charge the cam while it recorded.

 

[cranialrectosis]

Love how your plane almost 'parked' in the air when facing that light breeze.

The TT may be FTs most versatile plane. This variant looks to be another winner.

 

[duckduckgoose]

Love how your plane almost 'parked' in the air when facing that light breeze.

The TT may be FTs most versatile plane. This variant looks to be another winner.

Yeah I was testing how slow it can go, as it turned out, very. I still haven't pushed it to go fast but I'm sure it will absolutely shoot with that motor. I now need to build the trainer wing just so I can relax a little with the steering. Such a fun plane to fly, I bet you could even extend the wing out by 50% for even slower flying. Hmm now I have an idea... It basically feels just like the original TT but a little better in the wind.

 

[kilroy07]

See, I am not very good at LOS flying, I seem to struggle a lot with orientation, and I don't trust my brain enough. I know I just need practice but with these larger planes I much prefer fpv.

What I typically do is add a stripe or two to one wing (I prefer left) it really helped early on to get the brain and hands in sync.

 

[kilroy07]

Did you use a box spar or Just the flat piece of foamboard as in the original?

I had a box, but it wasn’t very tall. I might take a look at the explorer wings... 🤔
Either way I’ll definitely add something solid in the next wing!!

 

[duckduckgoose]

I had a box, but it wasn’t very tall. I might take a look at the explorer wings... 🤔
Either way I’ll definitely add something solid in the next wing!!

i also added some plywood. Even then i'm still too afraid to loop it haha The explorer wing is known to fold under stress probably because it only has two flat pieces of FB as the spar. i got rid of the middle dihedral and put two carbon rods either side of the FB spar

 

[mayan]

Love it’s presence in the sky! My next TT will be a larger one. I’ll probably up the plans to 200% so I can use 10mm FB. About the ply wood I added it internally before I folded it over. Just a thought.

 

[duckduckgoose]

Love it’s presence in the sky! My next TT will be a larger one. I’ll probably up the plans to 200% so I can use 10mm FB. About the ply wood I added it internally before I folded it over. Just a thought.

200% would be epic! yeah the plywood on the wing was more of an afterthought but that would definitely help. its such a nice design as a small original size plane but its even better as an upscaled model. i cant wait to send this thing up high with fpv. I cant imagine what flight time i could get on a 3000mah 4s.

 

[duckduckgoose]

Plans assembled for trainer wing with 500mm extension in the centre. Should make for a nice glider. May or may not cut it down further depending on how it looks when I have the foam cut out. My workbench is ...busy.

 

[kilroy07]

Short video of my Maiden

I'm thinking the Explorer wing might be an option as well...

 

[duckduckgoose]

Short video of my Maiden

I'm thinking the Explorer wing might be an option as well...

Great maiden! Flew around like a feather. I'm currently building the trainer wing with a 500mm extension in the middle. Hopefully nice and lofty.

 

[duckduckgoose]

Wing coming together. Ran out of tape and hot glue (more arriving tomorrow) but here is a size comparison with the original 150% wing and the extended trainer wing. Considering using @Hai-Lee 's idea for a slow wing with a double angle tip, but not sure if I need to, as I will be making the airfoil thicker than usual, and also because it might add a tendency to 'dutch roll'. Btw, the wing is inside out in the pic ( just showing size).

 

[duckduckgoose]

TLDR: what is the practical difference between an undercambered and flat bottomed wing?

Ok, so the wing is coming along well, I have the box spar in and am adding carbon spars in as I see fit. One thing I would like some input on though, is the undercambered wing. I noticed the sports wing was flat bottomed. I decided I wanted the trainer wing to be the same to add strength and also to accommodate the large box spar. But before I finish the wing I realised I should probably find out how this change might affect the performance of the wing. I can still cut the extra foam off and have a perfectly formed undercambered wing if I want.

 

[quorneng]

ddg
Undercamber
The way I look at is an undercambered wing will generate the same lift as a flat bottom one but at a slower speed. Like it has 'built in' flaps.
And just like flaps if you want to go faster it will need more power than a flat bottom section.
How significant these effects will be depends on just how much undercamber there is.

 

[duckduckgoose]

Wing complete. The wing looks absolutely huge, and now I begin wondering if it was a good idea adding the extra middle section. But hey, if it doesn't work, i have a big wing I can build a plane around

 

[duckduckgoose]

I know a polyhedral wing is supposed to negate the need for Ailerons, but I'm tempted to add some just to co-ordinate with the rudder (this being an excessively long wing). Would there be any point?

 

[Grifflyer]

I know a polyhedral wing is supposed to negate the need for Ailerons, but I'm tempted to add some just to co-ordinate with the rudder (this being an excessively long wing). Would there be any point?

It'd help in wind.

 

[quorneng]

The extending the wing span the bigger the fin & rudder has to be whereas the tail plane and elevator can largely be left 'as is'.
The problem comes down to the weight of the wings. Bigger span = bigger inertia so it needs more "rudder" to get it yawing so the dihedral can take effect to create the bank and just as important to stop the yaw so it returns to straight and level.

Outboard ailerons on the other hand actually get more effective at creating bank the bigger the wing span and thus they relegate the rudder to just adding sufficient yaw input to keep the turn 'neutral'.