ryanrink

this is my second attempt at designing my own r/c. my first was a 1/2a seaplane that im still trying to get the flight stability worked out. sense then all this talk about the design contest and watching all you creative master minds, got my fingers icthing to build something else. i went into the garage and starting brainstorming with some odds and ends i had. i've been wanting to build a skrike-ish or sig wonder type flying wing for awhile. i want to be able to get vertical performance out of a 1/2a engine but i wanted the building procces to be fool proof and ulta simple. i think i might have accomplished the second part because i got alot done tonight on it. the wings are from a big foam glider for kids they sell at wal-mart. i cut a 14inch section off each wing then cut channels in the roots of the new wings to put a dowel rod in, then expoxied the two halfs together with the rod inside the channel. (28in wing span) I then cut about a 4-5 inch length of thick-walled cardboard tube, i think its from a roll of monokote, and cut a slot for the leading edge to slide in and expoxied a plywood firewall to the other side. here is a VERY rough sketch to make it clearer, sorry im not good with CAD and dont have a digital camera but i really wanted to get your guy's opinions on it before i proceded with final assembly. hopefully this sketch is enough to get you a good picture of what its gonna looks like. i really would like to hear of any potential problems you could think of. stability problems? roll, pitch, yaw problems? cg placement on flying wing type (is there a difference?) how light weight would it need to be to get unlimited vertical performance from a norvel .061? anything would help. i got online tonight to see what i needed to do to enter the contest with it, but i got to looking at all your guys airplanes and there is no way i could compete, so im gonna leave the contest alone until next year and this will be for learning. there is so much talent around here. i would appreciate any help i could get. hopefully this sketch will work, its my first time posting a picture on here.

ryanrink

sorry guys, im having problems getting this pretty little picture i drew on MSpaint to work. i guess it'll just have to wait until i can get a picture of it or else become more computer savvy.

BMatthews

The file should be either a .bmp or .pcx file if it came from MSPaint.

But the pic presenter only works with the .bmp option if you can't save it as anything else. If you changed it to .txt to try to trick the system them it won't work. Try loading it up into MSPaint again but this time save it as a .bmp format and then upload that.

If it's large you'll have to load it into an image processing software first and resize the pic to 700 pixels wide or long max.

Or try reducing the size of the pic in MSPaint and save it with a new name to avoid ruining your original.

ryanrink

here we go again. thanks for the help, i hope it works.

BMatthews

Hey, that's better. We can see something now.

Sounds pretty good from what you wrote in the first post and the pic.

The only problem I can see is that most of those foamies are not symetrical airfoils and for such a short coupled model to work well it needs to use an airfoil that doesn't need much tail volume. Like a symetrical section or a self stabilizing flying wing section. But hey, it sounds like it's all but ready to fly by now and you don't have much money tied up into this so far. So why not keep it going. I'd go for the balance being at about the 25% mark and be ready with the elevator until you find out what's what.

Vertical performance comes down to thrust to weight. For decent vertical you need about 1 1/4 or better thrust compared to weight. 1 to 1 just ends up with prop hanging and falling around. This means you really need a model that's around 10 to 12 ounces tops. If your "bitsa" model is coming out to that sort of weight then you'll have the performance. If it's heavier you'll still be able to go vertical but you'll have to use the momentum for shorter climbs and push or pull out as the speed bleeds off.

Those wings were quite narrow as I remember. So at 28 inch span there's not a lot of wing area. I suspect it's going to be a fast flying handful. Good luck.

ryanrink

all i have yet to do is to install radio and put the tail feathers on. i'm still debating what i want to do their. i was kicking around the idea that sense it is a flying wing type to just use a big vertical stablizer w/o the V-tail i was orginally going to use. i wonder which would work better in spiraling slipstream effect. what do you think. i don't know to much about how elevons work or how effective they are. it is just a flat buttom airfoil, i hope thats not too much of a problem. i intend on it being fast, thats the plan anyway. thanks for the advice.

ryanrink

all i have yet to do is to install radio and put the tail feathers on. i'm still debating what i want to do their. i was kicking around the idea that sense it is a flying wing type to just use a big vertical stablizer w/o the V-tail i was orginally going to use. i wonder which would work better in spiraling slipstream effect. what do you think. i don't know to much about how elevons work or how effective they are. it is just a flat buttom airfoil, i hope thats not too much of a problem. i intend on it being fast, thats the plan anyway. thanks for the advice.

p.s. that was a very pesuasive speach the prez just made.

ryanrink

i think i decided to use the v-tail so i'll have more tail area...will elevons still work with a v-tail that doesn't have rudderator???? i decided to enter my design into the contest, i would appreciate any help. thanks guys!

ryan

ryanrink

here's a side view...im trying to think where the radio equipment should go...any ideas? i dont really like the idea of cutting into the foam wing. how much strength would that take away from the wing?