63 replies to this topic

[headhunter23]

clever... not sure I have enough, but darn that might even be more crash resistent than blue core and epp. Been doing measurments, I can make an 84" just barely fit in the back of the truck. Actually in photoshop it looks like 86" is my limit.

Thanks for the idea, hadn't come across it in my searches yet.


Ivan.

[headhunter23]

Ron, had looked around for depron, it's wierd we must not have it here so much in Kan a da, eh? As neither rc shop carried it and I wasn't willing to drive an hour and a bit to toronto to see if some of the stores had it there, so went with coroplast. Tried 4mm coroplast(4x8), decided to make 84" flying wing, wished I had taken photos to show you guys. Apparently when you make it out of one 8x4 sheet making both the top and bottom you can only make it 82" wide(this size weighs in 970g, for further testing, I'm going to get 2mm corroplast and reduce blue core that holds camera further). I compensated by increasing the foil height. Apparently I had gone too far as when I used spray foam for the centre blue core it increased the height of the foil even further than expected by an extra 1" taller(compared to zagnuts scaled up design). darn that is strong stuff for expanding, didn't think I put that much in, nor where it was stuck would it affect the foil so much. Anyways decided to try it, plane lifts off of pavement no problems, but can't do grass as needed. But it flys really really slow and needs a lot more power than I had used(too much drag). I think under full power of 2000rpm/v 60amps, spinning 8x4 prop, it's walking speed with 2.9kg all up weight. So changes that would be neccessary for this new plane would be to reduce the foil and change the motor. I have some 800rpm/kv motors but would mean taking off all the wheels and such and lengthening the height so the 15" prop can spin. Which was something I was trying to avoid, but at this weight it seems it's neccessary. Going to put this on back burner for a couple days to think about it.

In the mean time, due to yet another failed design, decided to give the old cularis wings a go, on a design I had seen a while ago. Not sure if any of you have seen the whispershots.com airplane or spoken to "power" on rcgroups.com(if your interested do a search on him there and check out all posts started by him and look around at ultra beast or something like that) but the design works, although I think it would be better with ailerons, as right now it's designed similar to easystar in terms of funtion and is much more affected by wind without ailerons. Very simple, light weight... am trying to lighten up as much as possible for this new plane. He has a really nice design for the wheels. He seems to make 4.5" wheels out of epp or some sort of hard black foam from computer cases that are insanely light and able to handle good load and don't require springs or heavy duty landing gears to take hits. The wheels are 4-8g depending on how they're made. Axel is carbon fibre rod... perhaps the lightest landing set I have seen thus far. The wheels and landing gear for my giant wing are over 200g, these include 3x3.5" "light wheels"(from hobby store) which seem to weigh in around 40g a piece plus all the metal for the shafts and wood to apply to body of plane. So for those of you looking to lighten up landing set, this guy has got a great idea.

Almost done the plane, tail section is just about done just need to mount servo and control surface stuff... main body needs a little more work in terms of wiring(just need to add y split for ailerons) and finally need to figure where exactly the wings need to attach. I'm sure I can get help from rcgroups.com about this but there's plenty o smart guys here... so quick question about wing placement. Do I determine where the wings go by completing everything then look for cg point on body where everything is balanced then cut out so wing cg point is in the same spot? Or is there much more math to figure out first(eiiiyiyi). Helps appreciated (btw there is plenty of room to plug wings to fuse, it's an ugly design...

Will have some photos up soon, at this point till I get a response I'm going to continue completing the body and tail stuff...

Ivan.

[W3FJW-Ron]

A good start Ivan, as you said would be to find the balance point of the fuse and then cut out for the wing matching the balance point to the wing COG. The fuse will have an aerodynamic bearing on the overall CG but it should be close and be able to balanced out by equipment placement.

Edited by W3FJW-Ron, 30 September 2008 - 12:36 PM.

[headhunter23]

Nice thanks for the reply, as I hoped.

Ivan.