Walmart $10 Glider RC Conversation

[SmokeshowFPV]

I strapped an AKK A5 setup that I stole off my tiny whoop to the tail of my twin glider yesterday. Had a blast with FPV until I had an unfortunate run in with some power lines.. oops haha. One thing the camera did catch is this, can you say wing flex? I have done tons a loops, square loops, wing overs and flat spins with this now, it's incredible that the wings are not breaking with this much flex.
Full video HERE

 

[SmokeshowFPV]

Aye, it definitely could use a few degrees of downward thrust angle. Maybe even an adjustable pivot for different power setups?

The design looks great by the way @kilroy07

I agree, it would be nice if it had like 5* of thrust angle. My print of the single pod just finished a little while ago so that is the next project.

 

[kilroy07]

Ah, you know what... (Just checking my design) it IS flat...
Ver.1.0 had 10 degrees down in fact (5 for the fuselage and 5 for thrust) when I crashed it (on a 3S) the pod snapped right off, so I beefed that up on ver 1.2 BUT apparently didn't add the down angle...

Geese, I'm sorry guys!! Although I really feel bad about wasted filament, I DO really appreciate the feedback!
As I said, I've only been in the hobby for a short while, so I'm still not sure if an issue is a design or "pilot" issue yet.

I'll edit the design tonight and get an updated copy up there ASAP!
You think 5 is enough, or maybe 10 (I thought I saw about a 5 degree slope in the back relative to the wing...)

I too noticed the tip-stall (I think it's even in my video...) I wonder if that's due to the height of the pod... (the twin having a lower CG? or maybe the torque flipping it as she slows... Mine always dropped the right wing.)

There's some extra clearance (I wanted to allow a couple different props) I wonder if I should lower it a bit (thoughts/suggestions?)
I could make it variable.... A separate motor mount would allow more options...

 

[kilroy07]

can you say wing flex

YES, Yes I can... LOL

I have a second design, but I seriously think it would need bracing based on what I saw too!
(My wings flexed like that on the 3S... you know... right before the... Uh humm... "Landing"...)

 

[Namactual]

I think I would start with 10*. That is sitting a ways above those wings. I dare say she might need more than that, but I am just going with my gut.

My gut says 15-20*.

Maybe someone esle will chime in. I am sure @Hai-Lee would have a better idea.

 

[kilroy07]

Here is where I found the CG, Does that jive with what others have found?

 

[kilroy07]

Updated on Thingiverse.
https://www.thingiverse.com/thing:2948067

 

[Hai-Lee]

I think I would start with 10*. That is sitting a ways above those wings. I dare say she might need more than that, but I am just going with my gut.

My gut says 15-20*.

Maybe someone esle will chime in. I am sure @Hai-Lee would have a better idea.

Well if you insist,. My estimate is closer to 60 degrees.
Seriously though the ideal solution for a pusher or almost any plane for that matter is for the motor thrust line to go through the planes centre of gravity. Sadly for a power pod swinging large diameter prop on a small plane this is definitely not practicable. To lessen the nose down push of the pod a degree of up thrust angle, up to 10 degrees max, should be considered along with the removal of the 2 blade prop and fitment of a 4 blade prop of much smaller diameter. This would allow the reduction in the height of the motor above the fuselage centre line and a marked reduction in the nose down push. This reduction in mount size would give a benefit is lower stall speeds due to the weight reduction inherent in a smaller powerpod.

In addition a mix could be considered of adding a little throttle to the elevator such that as the throttle is increased a compensating amount or degree of up elevator is added. Such a mix would be best made switchable so that at high speed cruise the mix can be removed.

Have fun!

 

[mrjdstewart]

 

[Pigfarm1403]

holy crap. those pictures are beautiful, nice camerawork

 

[mrjdstewart]

i started @ 60mm from trailing edge, i'm now @ 65mm. also added some wheels since she seems to want to dive before hand launch. no sense in nosing into the ground when it will fly up on it's own...

with the 3S i plan to fly on next, AUW is 462g. emax's website reports a 712g thrust on 3S using a 5x4.5 2-blade. i am using a 6x4.5 2-blade, maybe i should try a 5x4.5x3blade? might help with some of the torque effect?

laters,

me

 

[mrjdstewart]

...and as you can see. you can't make those elevon's big enough. a 'whole lot of junk in front of that trunk...

 

[Hai-Lee]

If you are unsure of the CG which should have been mentioned on the original manual then you should take a few measurements and use one of the on-line CG calculators.

have fun!

 

[mrjdstewart]

there was no manual, and yes i could use Ecalc and spend a lot of time taking measurements and entering data to find the perfect-ish CG. did i take the time to do that...no.

i assembled the kit prior to mods. marked the natural CG, and went from there. the rest is just fun!

laters,

me

 

[kilroy07]

i assembled the kit prior to mods. marked the natural CG, and went from there. the rest is just fun!

Same here, That's what the image above showed (where I had marked the natural CG.)

I also have a 5" 3 Bladed laying around I will try that.

I have some ideas, but for now (after posting the down angle fix) I will have to set this project aside while I work on others (probably after FF Ohio.) Oh, yea, and there's the "Day Job..."

 

[kilroy07]

...and as you can see. you can't make those elevon's big enough.

That's why I threw the image of where I found the CG, I didn't have any nose down tendencies on launch. A little up trim, but not much (I actually don't "trim" I fly with a little back pressure... got me in trouble with my flight instructor too...) I just wondered about your CG too far forward (based on pics.)

If I measured mine (Pish, who measures the CG?! ) it is 45mm "ish" from the back of the wing slot in the fuselage. From there if you go out about 130mm to the wing there's a molded impression (I took that as the recommended CG) and based my design on.


I definitely did see the tip stall though.

 

[kilroy07]

I definitely did see the tip stall though.

And I believe that's due to torque... Which just MIGHT make this the perfect warbird trainer!
Mustangs here I come!!

 

[mrjdstewart]

flew my single pusher again the other day on a 3S-850 LiHV using my newly designed wheel gear.

well, gear alignment needs some work , but once in the air it flew great. it obviously had more power and was able to climb much quicker. once up in the wind (100+ft) you could chop the motor and the wind on this half-sock kinda day was usually enough to keep it gliding. a little down elevator to gain speed if needed. unfortunately it still had the same nasty tip stall if you dared to go to slow. on landing i was on a beautiful, smooth approach, then 3ft off the ground. left wing dropped suddenly and the plane tumbled over. so basically, no matter how nice it looks. you have to fly this plane to the ground @ power, then chop and flare at last moment.

laters,

me

 

[Sabin]

Finished mine last night. I got rid of most of it -- essentially turning it into a wing. Dropped the glide speed so low, I can chuck it inside the house and it stays aloft for a couple seconds before hitting the wall. Maiden is today if the weather stays clear.

 

[Sabin]

A fair bit gustier than I planned on, but I went for it. Sound is very pleasant to hear, decent response but it was hard to judge its performance. I'll give it another flight when it's calmer.