ANNOUNCING NARAM-46

A NIRA member had one of these that flew on HPR motors. Perhaps J...

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Maybe. An infinite flat plate wing will produce a lift curve slope of

2*pi/radian angle of attact from zero AOA, exactly like an aairfoiled section. However things diverge from there. The flat plate will tend to have separation bubles and eventualy full separation (e.g. stall) long before a well desgned airfoil section. However, Chris' model is essentialy a delta wing where high AOA lift is due largely to the formation of large vorticies over the wing rather than that due to 2D airfoil aerodynamics.

Alan

how much drag could an airfoil reduce on a wing nearly 8 feet long (model is

11ft)

especially when you consider the HUNDREDS of hours it would add.

and then you consider that I would have to GLASS the entire thing (the only way to add a foil would be to remove the poly/mylar skin that provides all the stiffness in the wing structure. without it the wing is a floppy noodle (literally)

the IMMENSE time penalty and massive MASS penalty would eliminate ANY benifit gained from the airfoil.

Chris Taylor

I built a Blustick park flyer by doing just that; removing the skin off the foam. To form a airfoil I used a heat gun. For extra strength I also added a CF spar on the leading edge. It's amazing what you can do with a heat gun and foam board. I was able to toughen up the skin a bit as it appear(to me at least) to offer a bit of extra durability to the foam. Obviously the CF rod provided the critical strength.

Check out

for some real good tips on dealing with foam board/blucore foam. It's truly amazing what can be done with the stuff.

On a side bar I'm working on a true sub $100 RCBG wing using the stuff and that price include the complete radio AND launcher. If I'm lucky it should fly good on minimal C11 power. Actually I think could pull the whole thing off for well under a hundo complete.

Ted Novak TRA#5512

I too am working on just such a project. READY to go for under $100 everything included.

problem is power verse size. to small and it gets sensitive and complex but too large and you need D power (My goal is C6 power) since on sale that brings it to $1 a flight which is my objective.

I am working on a new design similar to the old estes soaring eagle. this would allow higher total ahnds off boost and yet large nice glide wings. the free flight worked great. I am working on a version twice the size but with full 2 channel control. I am still working on a reliable release to swing the wings without having to depend on the ejection charge.

also reliably sourcing the radio gear is troublesome.

Chris Taylor

You might find that a Sprice/Balsa and Monokote wing is lighter, thicker, lower drag, stronger, cheaper and about the same or just slightly higher labor.

Jerry

Verrrrry funny Jerry,very funny :)

actually a balsa built up wing is 10-20 times the labor but it is what I am going to build.

reason. I want to make th emodel module so I can break it down into 4 parts for eacy storage and transport.

also by building up in wood I can built in "hook" point to add landing gear and a gas engine when I wish to fly it as a normal off runway RC airplane.

the only reason I am doing this is because I now have plenty of time.

it will still be a flat wing but same as foam with shaped leading and trailing edges.

I am going to make the wing thinner (1" thick) to reduce the drag this adds over 100ft in altitude in the sims.

Alan Jones wrote in news: snipped-for-privacy@4ax.com:

What mass fraction is converted to energy when you split an infinitive?

len.

I think these links will get you brainstorming;

**&P=0 You could recoup some costs by selling the stock servo's back on ebay. As far as a battery pack I'm thinking something like a cheap 9v nicad pack from Target or Wally World. That's about 75-80 bones for a 2 channel single stick radio with mixing and micro servo's. Not too shabby.

As far as the RCBG I thinking of a foam core 30" flying wing. At Target a single sheet of poster foam board is about $3. Total flight weight would hover around 3-4 oz max. I think a C11 could handle it. D12 when you wanna go nuts. A E9 would be interesting :)

Ted Novak TRA#5512

Chris Taylor Jr wrote:

actually I decided months ago to go built when I saw the deteriorating wing in the garage taking up HALF the entire garage :-)

it just too darned big. I can not do modular foam. too much mass would have to be added to "strengthen" the joints. it just would not work well.

Balsa build up though I can "design" to be modular quite easily.

the only problem is that it will be VERY VERY Expensive. that much balsa (and it will all be laser cut for other reasons) is going to be very expensive. I will not be surprised if I spend $200 in balsa alone.

Exactly how is reducing the wing mass a penalty? Reduction of mass would have been critical to this model. How much dod those foam sheets weigh?

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

This is a BOAT radio, not available on 72 MHz aircraft frequencies.

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Also, it's an AM radio, not an FM. AM radios are much more susceptable to interference, and although there are a few aircraft AM radio systems available, I wouldn't trust one to fly anything that I've put hours of work into. Penny-wise, pound-foolish, as they say.

Shaping the edges might be the best thing to do... lot easier than trying to airfoil a whole wide thin panel... like a basic "partial airfoil" job on a model rocket fin: taper the trailing edge, round the leading edge, most of it remains flat.

I'm not even sure, on a big delta like that, if it's even going to matter all that much, especially when the nose is raised to make lift at low airspeed: I wonder if the dominant factor would be "wing lift drag" rather than "edge noise drag" anyway - i.e., mainly the force required to pull the big panel forward while it pushes air down and makes lift. (Someone like Len or Brett might know the correct words all this - I'd have to go look them up.)

He's saying that if he airfoiled the wing, in addition to the time required to carve the shape into the foam (possibly difficult to do on that chord, span, and thickness without inadvertently introduce any asymmetries that might make it do strange things on boost), he'd have to add mass to the wing by glassing it if he carved down to an airfoil shape, but by leaving the panel flat he gains stiffness from the mylar facing it's manufactured with (which is lighter than any glass job he could do).

He'd rather have a lighter flat plate than a heavier, labor-intensive glassed airfoil.

To airfoil such a wing and retain the stiffness of the mylar facing, without glassing, it would be necessary to find similar foam in half the thickness, make two mirror-image pieces of each panel, peel the film off the mating faces, half-airfoil each peeled surface, and then glue the pieces together so that the outer film-covered surfaces took on the airfoiled shape when the carved inner surfaces were pressed flat against each other. (Jigging up the glue job so that the lamination came out perfectly aligned might be a significant challenge, and any misalignments might make it do strange things on boost...)

-dave w

that is just it BOB it would NOT reduce the mass it would INCREASE IT since I would have to glass the wing to READD the strength lose by removing the poly/mylar coating (which is where it gets almost ALL of its strength and stiffness from) it is literally a wet noodle without the coatings (I know I tried removing it and ruined one wing)

so by the time I added enough reinforcement to make it stiff again it woudl weight MORE and have cost me hundreds in hours and dollars to do.

all for a tiny drag improvement that would be hugely overshadowed by the huge mass increase.

27mhz is a legal aircraft frequency (it is valid for both air and land)

72 is air 75 is land 27 is land and air.