Combat Plane Building Material
06-17-2003, 01:36 AM
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Combat Plane Building Material
In another post I have been convinced that the modern combat flyer wants a good flying midair surivable plane. I want to design a new Class B plane. There are two things it will have to have. It will be a flying wing and it will be made out of foam. Here are some questions I would like to ask.
What type of foam do you prefer?
White
Pink\Blue
EPP
What kind of material would you like the control surfaces, Fin and Elevons to be made out of?
Balsa
Coraplast
Other
What kind of hinge material do you prefer?
How large of a Fuel Tank?
6 oz
8 oz
What final all up weight would you consider good?
I plan on putting a 1/8" plywood piece laying flat inside the leading edge of the wing. Is this a good or bad thing?
What kind of covering would you prefer?
None
Tape
Heat Shrink
What's more important to you in an airplane?
Speed
Turning ability
Survivability
If I know what kind of plane you combat flyers are looking for I might just be able to design something to fit your needs.
John Boren
What type of foam do you prefer?
White
Pink\Blue
EPP
What kind of material would you like the control surfaces, Fin and Elevons to be made out of?
Balsa
Coraplast
Other
What kind of hinge material do you prefer?
How large of a Fuel Tank?
6 oz
8 oz
What final all up weight would you consider good?
I plan on putting a 1/8" plywood piece laying flat inside the leading edge of the wing. Is this a good or bad thing?
What kind of covering would you prefer?
None
Tape
Heat Shrink
What's more important to you in an airplane?
Speed
Turning ability
Survivability
If I know what kind of plane you combat flyers are looking for I might just be able to design something to fit your needs.
John Boren
06-17-2003, 01:50 AM
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Combat Plane Building Material
John,
I have one opinion for you but I hope you use what works best for you. In order to be competitive, my planes need to be able to go about 85 miles per hour. Turn in about 20 feet and be tough enough to dive into the ground with minimal damage. All these thing we try to design in when we build. As for the durability, it is not always strength that survives a mid-air. Sometimes the ability of the wing to move out of the way as well as absorb the impact will let you "fly out". I have my planes set so that you can push the wing back almost to the tail and it will spring back in place. Coro seems to be the toughest for the control surfaces, and as far as the tank size. The plane needs to be able to go full throttle for at least 8 minutes.
Bob
I have one opinion for you but I hope you use what works best for you. In order to be competitive, my planes need to be able to go about 85 miles per hour. Turn in about 20 feet and be tough enough to dive into the ground with minimal damage. All these thing we try to design in when we build. As for the durability, it is not always strength that survives a mid-air. Sometimes the ability of the wing to move out of the way as well as absorb the impact will let you "fly out". I have my planes set so that you can push the wing back almost to the tail and it will spring back in place. Coro seems to be the toughest for the control surfaces, and as far as the tank size. The plane needs to be able to go full throttle for at least 8 minutes.
Bob
06-17-2003, 10:25 AM
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Combat Plane Building Material
Don't use white foam, it just disintegrates on almost any impact. The pink foamular 400 or 600, or the blue hiload 40 or 60 work great. I think the plywood may be too stiff, and not transfer the energy from impact as well as fiberglass rods. I use 1/8 fiberglass rods for the leading edge, and top and bottom spars. Then cover with ripstop nylon and polyurethane.
For tail surfaces, coroplast is by far the easiest, and works great. You might want to stiffen them up with either fiberglass rods, or even just wooden dowels pro-bonded into the flutes in a few places. For ailerons, I use 3/8 by 1 1/2 aileron stock which has been attached with bi-directional strapping tape, and then ripstopped on.
Use whatever size fuel tank will give you 6 minutes of wide open flight time.
I have covered wings with bi-directional tape, and it is very UV sensitive. It is strong, but deteriorates very quickly. I have also used sign vinyl, which works ok, but ripstop nylon is better.
survivability is important to me, but flight stability is way high on the list too. I think the actual speeds the average combat ship flys at 60-65 mph, but should not give up too much speed in turns.
For tail surfaces, coroplast is by far the easiest, and works great. You might want to stiffen them up with either fiberglass rods, or even just wooden dowels pro-bonded into the flutes in a few places. For ailerons, I use 3/8 by 1 1/2 aileron stock which has been attached with bi-directional strapping tape, and then ripstopped on.
Use whatever size fuel tank will give you 6 minutes of wide open flight time.
I have covered wings with bi-directional tape, and it is very UV sensitive. It is strong, but deteriorates very quickly. I have also used sign vinyl, which works ok, but ripstop nylon is better.
survivability is important to me, but flight stability is way high on the list too. I think the actual speeds the average combat ship flys at 60-65 mph, but should not give up too much speed in turns.
06-17-2003, 02:25 PM
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Q: What type of foam do you prefer?
EPP, though it's heavy, expensive, and toxic to cut. So I settle for Pink\Blue. I'm using 25 and 40psi values (foamular 250 and foamular 400/hiload 40)
Q: What kind of material would you like the control surfaces, Fin and Elevons to be made out of?
Horizontal and Vertical stabs and elevator are coro. Ailerons are balsa. I cover the balsa ailerons top and bottom with bi-di tape under tension.
Q: What kind of hinge material do you prefer?
I've gone to 100% packing tape hinges. I just use the over-under trick to make them really solid.
Q: How large of a Fuel Tank?
6oz on all 2610/B class planes 3oz on A and SSC planes. You need 6min of full bore flying with out sucking air as sheepy said. If you have 8min of fuel, that's extra weight you don't need on board. If you run out of fuel right after stop-combat, you got it perfect.
Q: What final all up weight would you consider good?
No such thing as too light. For B class, get it under 3lbs, though in reality anything legal that turns well will get the job done.
Q: I plan on putting a 1/8" plywood piece laying flat inside the leading edge of the wing. Is this a good or bad thing?
Bad thing. It won't stand up to a wing-to-wing hit.
Q: What kind of covering would you prefer?
I'm using rip-stop and/or polyester right now. Packing tape is also ok, I use it in the other classes, and might experiment with it in B class. It won't be as strong, but should be faster to field repair, and frankly, it's the props that keep eating up my planes and nothign stops a prop cut. Heatshrink looks nice, but it seems to tear like crazy on impact.
Q: What's more important to you in an airplane?
Turning ability, no question.
Q: that should have been asked - What wingarea/wingloading is about right:
Get it over 500sqin. min. 600+ is better for a 3.5lb plane.
EPP, though it's heavy, expensive, and toxic to cut. So I settle for Pink\Blue. I'm using 25 and 40psi values (foamular 250 and foamular 400/hiload 40)
Q: What kind of material would you like the control surfaces, Fin and Elevons to be made out of?
Horizontal and Vertical stabs and elevator are coro. Ailerons are balsa. I cover the balsa ailerons top and bottom with bi-di tape under tension.
Q: What kind of hinge material do you prefer?
I've gone to 100% packing tape hinges. I just use the over-under trick to make them really solid.
Q: How large of a Fuel Tank?
6oz on all 2610/B class planes 3oz on A and SSC planes. You need 6min of full bore flying with out sucking air as sheepy said. If you have 8min of fuel, that's extra weight you don't need on board. If you run out of fuel right after stop-combat, you got it perfect.
Q: What final all up weight would you consider good?
No such thing as too light. For B class, get it under 3lbs, though in reality anything legal that turns well will get the job done.
Q: I plan on putting a 1/8" plywood piece laying flat inside the leading edge of the wing. Is this a good or bad thing?
Bad thing. It won't stand up to a wing-to-wing hit.
Q: What kind of covering would you prefer?
I'm using rip-stop and/or polyester right now. Packing tape is also ok, I use it in the other classes, and might experiment with it in B class. It won't be as strong, but should be faster to field repair, and frankly, it's the props that keep eating up my planes and nothign stops a prop cut. Heatshrink looks nice, but it seems to tear like crazy on impact.
Q: What's more important to you in an airplane?
Turning ability, no question.
Q: that should have been asked - What wingarea/wingloading is about right:
Get it over 500sqin. min. 600+ is better for a 3.5lb plane.
06-17-2003, 04:41 PM
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Take a look at Lee Liddle's Falcon flying wing design, it comes pretty close to state of the art for combat flying wings. There is a review of it on the www.georgiacombat.com site.
It uses a combination of blue foam for the leading edge and white foam from the spar back to the trailing edge. This arrangement combines strength where its needed and lightness of the 1lb white foam. I like this combination and have started using it on my SSC planes, will do the same for Open B when my stock of Hat Trick cores runs out...
The Falcon is probably the tightest turning and fastest design out there right now, its also very easy to build and field repair, but flying wings just don't fit my flying style, so I don't fly them...
Balsa for the ailerons and coro for all other control surfaces. Coro is too flexable for use in long aileron or elevons.
Packing tape hinges are quick, easy and tough and don't pull out like CA hinges do...
Covering, I go back and forth between WBP/RSN and packing tape. Packing tape being less messy and not as time consuming as the RSN..
I use 1/4" polypropylene leading edges which spread out the impact loads without breaking the wing...
The rule is to build it so things bend, not break.
What wingspan are you looking at in your design?
It uses a combination of blue foam for the leading edge and white foam from the spar back to the trailing edge. This arrangement combines strength where its needed and lightness of the 1lb white foam. I like this combination and have started using it on my SSC planes, will do the same for Open B when my stock of Hat Trick cores runs out...
The Falcon is probably the tightest turning and fastest design out there right now, its also very easy to build and field repair, but flying wings just don't fit my flying style, so I don't fly them...
Balsa for the ailerons and coro for all other control surfaces. Coro is too flexable for use in long aileron or elevons.
Packing tape hinges are quick, easy and tough and don't pull out like CA hinges do...
Covering, I go back and forth between WBP/RSN and packing tape. Packing tape being less messy and not as time consuming as the RSN..
I use 1/4" polypropylene leading edges which spread out the impact loads without breaking the wing...
The rule is to build it so things bend, not break.
What wingspan are you looking at in your design?
06-17-2003, 04:58 PM
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Wing Span
Right Now it has a 52 inch wing span. I can make it a little longer if needed. Also what size fule tank are you using. People have stated "whatever size tank you need to get 6+ minutes of full throttle flingt" Will four ouncse work or does it have to be a 6 ounce tank. I currently fly a OS MAX .28 ABC engine and 6 ounces of fuel is more then enough.
John Boren
John Boren
06-17-2003, 05:26 PM
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The longer the wing the better.Two years ago, 52" would have been considered long. Today 64" is considered short, and 72" is very common. Think of the wing as the guns. With 52" you have the equivalent of a .30 cal. With a 72" or greater, you change that .30 cal to a guided rocket. Use a big enough fuel tank for 6 minutes of WOT. 4 oz might do it for some, and 6 will for others. Some may even have to go to 8 oz.
06-17-2003, 07:36 PM
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I currently fly a OS MAX .28 ABC engine and 6 ounces of fuel is more then enough.
