Wright Stuff B

[carneyf1d]

i just got started on writing a program that determines the aspect ratio, thrusts and drags, lift, and hopefully endurance, based on angles of attack, rubber, prop efficiency, weight, etc from user input. i got a good start, and hopefully after a few times testing with some rubber, it might be useful for all you people in wright stuff.

[bob3443]

I'm just wondering, although i know its illegal, but are there benefits of making wings and stabilizers from solid balsa?
Also i'm just wondering, has anyone tried any other device other than an "airplane"?

[andrewwski]

No, that would just make it heavy. And very hard to put the appropriate curvature into.

[carneyf1d]

im not sure what you mean by another device other than an airplane. the event rules make it pretty hard to construct something other than a plane.

[carneyf1d]

heres a hint that could possibly add MAJOR time to your plane. add flaps, ive seen it partially done before, but ive never seen anybody fully make one with decent flaps. Flaps raise the coefficient of lift of the plane from around 1.25 to 2 or so. i havent had a chance to play around with this idea....but it is great food for thought. to make a flap just make your ribs have a 30-45 degree bend from 4/5 the chord to the trailing edge. it might look weird, but give it a try and who knows!

[bob3443]

what do you mean by "flaps"?

[smartkid222]

that sounds intersting carney, i remember from when i used to do the microsoft flight simulators it siad that flaps would increase the stall speed (and i think increase lift, while decreasing speed, or something idr).

[jander14indoor]

Note, this is one of those advanced discussions. Unless you are already flying two minutes plus under the current rules, spend time on other things like weight and basic trim! Then work on matching prop an rubber. Until you are in the three minute range. After that, look at these kinds of things.

With that out of the way...

Flaps do two things for you on a wing, allow you to change the area by increasing wing chord, and allow you to change the camber of the wing and thus the lift coefficient. Note the word change, there's nothing magic about flaps.

This is useful on full size (and some model) airplanes (see smartkid222 comment) because of the wide range of flight conditions they must fly under. They allow a plane with a wing optimized for high speed (where for example an airliner spends most of its time) to take-off land at much slower and safer speeds and shorter distances. For a wing operating under a single or narrow range of conditions, it is probably better to just increase the basic wings chord or camber directly.

Not so useful with this years rules as there is no limit on chord, and the speed ranges are such that you can just build in the camber you need. You can get all the benefits to lift from flaps without their drag and weight.

Unless you are talking about adjustable flaps. If adjustable only while not flying, I'd suggest making several wings for different conditions instead. If you can make ones that automatically adjust in flight (no RC control now) I'd LOVE to see how you mechanized that!

Now, there is another wing design feature often associated with flaps called a 'slot' that MIGHT be useful. For long chord wings or sharply curving cambers or high angles of attack (all possible for the flight conditions of Wright Stuff Models) you can sometimes have a problem where the air flow separates from the top of the wing reducing lift. A slot can be used to delay or eliminate separation, maintaining high lift under those extreme conditions. Search internet for theory to understand this better. But note, separation has not been a problem under past WS rules, and I've never seen slots on the most extreme of indoor models so...

And make sure you don't implement slots so some judge thinks you have tandem wings, clearly illegal under current rules.

Jeff Anderson
Livonia, MI

[bob3443]

I'm getting about 1:00 - 1:20 flight times( i know its pretty bad, my first actual working plane) its about 6.5 grams(yes i know it has to be at least 7 grams) i was what i should do with the extra .5 grams i need to add should i make my wing cord longer? its about 9.75 cm right now, should i add more ribs to my wing? it seems to be breaking between ever 3 or so flights. should i make a larger vertical stabalizer? should i make the whole airplane longer? its about 41.5 cm long
Thanks in advance.

[jander14indoor]

For a first plane, 1:00 to 1:20 is a good starting point. That means you are flying! Now you can start learning what it takes to fly even better, hard to do when all you do is crash.

Suggestions on next steps. You say you are breaking every 3 or so flights. Why? Handling? If so, you'll get better at that. Weak points? Same spot generally? Rebuild your plane putting that half gram in the 3-4 spots where its breaking most often.

9.75 cm chord is a perfectly good starting point, I wouldn't sweat that much yet.

Ribs, how many do you have? Most use 5-7 ribs just fine. If you are in that range, you are probably OK there. If your ribs are breaking often, you may want to select the wood more carefully. They generally aren't a problem unless the grain is running cross wise.

Larger vertical stabilizer, why? Is your plane in consistent in direction? If not, leave that alone. Too large is every bit as bad as too small.

Length, 41.5 is OK, maybe on the short side.

Actually before you spend too much time modifying your plane (other than strengthening your weak points, you'll probably be wiser to spend your time flying and trimming. A well built plan at the size and weight you mention will fly much longer than you have so far.

What size motor are you using? What size and type of prop? How many winds? What's the plane doing (besides just flying). Do you get to the ceiling? How high a flying site? How big a turn. Etc.

Let us know!

Jeff Anderson
Livonia, MI