The Wright Stuff

[Illuminati]

I didn't come up with the name, science olympiad did.

 

Anyways, I have joined my schools science olympiad team, and I have chosen the task of creating a model aircraft to fly for over 2 minutes minumum.

 

I'm sure some of you have been in science olympiad before and have even participated in this event, so, I thought this would be an ideal time to pass this design I came across onto you.

 

The rules are located here; http://www.tx.ncsu.edu/science_olympiad/Tournament_information/Event_rules_nc/wright_stuff_b_06.htm

 

And the design I want to emulate looks similar to this;

 

And this is the one that most people tend to build;

 

The only things we are allowed to use are; balsa wood, glue, paper, and most recently, plastic film, which is what I plan to use. In fact, I hope to use the kind of plastic film that has shrink wrap qualities, so no glue is required and will create little, if no, ripples on the wing and tail.

 

Most people use the store bought plastic prop, however, being that it is so small, the rubber band expends all of its energy quickly and has none left for extended flights. I suspect that the propellor will just get the plane up to speed quickly and not keep it aloft for more than a minute or so.

 

However, the wing design and basic construction across most aircraft are the same. So the biggest difference between normal designs and the one I would like to emulate is in the prop. Supposedly, the larger prop spins much more slowly and expends its energy at a much slower rate, in addition, the design is very light and does not require a great amount of thrust to get off the ground, so, the slow prop design should work.

 

However, my only concern is the propellor is going to be very hard to construct, being that it is constructed from balsa wood, I am worried about it not being able to bend at a sufficient curve before breaking. Hopefully I'll be able to shave it to a small enough thickness that it will bend without much trouble.

 

According to people who have built this and flew it in large open areas, the model flew for nearly 30 minutes, although I have reason to doubt the claim, it could still prove to be fun even to just try.

 

So, what do you guys think?

Do you think it will work? Or even have a chance?

[ecoli]

Ahh, I remember my science Olympiad days. There was a kid on my team that was awesome at Wright Stuff. He got well over 5 min. when he did it. His problem was that the airplane hit the Gym cieling, which cut his time down (energy loss) Of course, in the national competitions, it's done in an Airplane hangar, and the first place teams get around a .5 hour, or so I've been told. Good luck to you.

[Illuminati]

Interesting, you wouldn't happen to remember what kind of build he used would you?

Well, at any rate, thankyou, I certainly hope to do well.

[YT2095]

rather than "shaving" it to keep the wieght down, consider drilling holes through it at regular intervals instead, at a 90 degree angle to where force is going to be applied.

 

like o o o o o o o o type if you were to be pushing at your monitor screen.

 

hope ya catch some really good air, Good Luck Dude! )

[Illuminati]

rather than "shaving" it to keep the wieght down' date=' consider drilling holes through it at regular intervals instead, at a 90 degree angle to where force is going to be applied.

 

like o o o o o o o o type if you were to be pushing at your monitor screen.[/quote']

 

Are you talking about on the propellor? or along the body of the plane? (the shaft of wood (haha) where all the wings are held in place and above the rubber band motor)

 

I feel that along the body would reduce weight more than anything. I just see problems with drilling holes in the propellor, unless it's smooth, the wind would be disrupted and cause drag on the propellors and would spend more energy fighting against the wind than it would if it didn't have the holes.

 

hope ya catch some really good air, Good Luck Dude! )

 

Heh, thankyou, I certainly hope so as well.

 

Unfortunately, I've been told that I need to create a base plane first, with just a plastic propellor before I can go more advanced. Although this is probably good, it is more time consuming and we only have 3 weeks left and I haven't even started yet.

[YT2095]

your prop will need to be as smooth as possible and so, unless you plan on plasti-coating both sides (I`de reccomend that anyway), then no, do NOT drill them!

 

for the rest, I say do it where practicable, even if it`s only one hole every 3-4 cms or so, it still buys you Mass

 

Not V pressure

[ooooooooooooo] push your monitor towards these drill holes is correct!

Not ^ pressure

[Illuminati]

Haha, alright, just wanted to clarify. I thought you knew something that I didn't.

[gcol]

Re: propellor

 

Read the rules. The assembly may be home made, but the prop itself must be plastic store bought, of a certain maximum diameter diameter.

 

Discover the power-on duration. Subtract from desired total flight time. Remaining time must rely on glide efficiency. Trim motor run to finish at max. ceiling height, then trim for best glide, ( make sure the prop cn freewheel with minimum friction) paying attention to turning circle to avoid hittng walls. There is much more art than science to this, and if you can do all that within three weeks, you live in a different time scale to me.

Good luck.

[Illuminati]

Read the rules. The assembly may be home made' date=' but the prop itself must be plastic store bought, of a certain maximum diameter diameter.

[/quote']

 

Did read them, just didn't go over them in that great of detail.

 

Well, that sucks, that certainly puts a damper on my entire plan crap.

 

Well, I still have a few tricks left up my sleeve.

[YT2095]

btw, I MAY have missed something, but what is this craft meant to powered off or by?

[gcol]

btw, I MAY have missed something, but what is this craft meant to powered off or by?

 

A rubber motor. You did not read the rules either.....tut tut. I thought you were resourceful!

[YT2095]

LOL, you may be certain that I Am, I think the prefered word that you might have wanted to use would have either been "Observant" or words "not so Tired".

 

and so, if we cut all the crap, the answer to my previous question is a Rubber band!

 

 

thanks, nice we kept all that so simple

[Klaynos]

I would make an attempt to make the surface area of the top of the wing creater than that of the bottom, as in a more modern wing design :\

[gcol]

LOL' date=' you may be certain that I Am, I think the prefered word that you might have wanted to use would have either been "Observant" or words "not so Tired".

 

and so, if we cut all the crap, the answer to my previous question is a Rubber band!

 

 

thanks, nice we kept all that so simple [/quote']

 

By golly, you've got it! 39 posts and at last I have said something sensible.

[Illuminati]

I would make an attempt to make the surface area of the top of the wing creater than that of the bottom, as in a more modern wing design :\

 

I was actually considering that, however, what advantage will that give over the flat wing design?

[gcol]

I was actually considering that, however, what advantage will that give over the flat wing design?

 

A flat, top and bottom, wing gives low lift and high aerodynamic drag (bad).

A curved (cambered) top surface gives more lift and a little more drag Induced profile drag)

Cambered top and bottom gives best lift/drag ratio at the flying speeds normal to flying rubber powered model aircraft.

[Illuminati]

A flat' date=' top and bottom, wing gives low lift and high aerodynamic drag (bad).

A curved (cambered) top surface gives more lift and a little more drag Induced profile drag)

Cambered top and bottom gives best lift/drag ratio at the flying speeds normal to flying rubber powered model aircraft.[/quote']

 

Thankyou very much, that information is going to help me alot!

[gcol]

But wait, there's more:

1. Flat section easy to construct but inherently weak and twisty.

2. Flat bottom, cambered top, less easy but stronger and twist (warp) resistant, Greater strength brings a weight penalty. (bad).

3. Cambered top and bottom, constructional problems, tendency to weakness and warping.

 

2 has more stable flight characteristics, the model will be easier to trim.

3 ultimately most efficient, but because the centre of pressure/lift wanders about between trailing and leading edges according to flight speed, and the relation between centre of lift and centre of gravity is crucial, stable flight more difficult to achieve.

 

Probably best to build from a published design or kit. You will have to investigate the aeromodelling trade. Cant help there, I am too out of date.

It can be an absorbing hobby.

[lightwave]

The holes in the mainframe is a good idea. That will save a few grams of weight.

 

Wing design will be crucial to flight time too as well as an efficient propeller.

 

Have a look at the 'butterfly' at Plantraco's website. It's a 3.8 gram flyer with electric motor, battery, controller and reciever. You are making a glider, so the electricals are of no interest to you, but the plane's construction might be what you are looking for.

 

Balsa is very strong for it's weight. You could make all the spars very thin indeed before they get too weak. Expect to make a dozen or more models.

[gcol]

Sorry, lightwave, you have not actually read the rules, although your suggestions are all worthy in general aeromodelling terms.

[Illuminati]

hmm, I was just thinking, carbon nanotubes, I wonder how hard it would be to get a hold of a sheet of that.

 

I wonder how it would hold up as the skin for a wing. ^^

 

Heh, I wonder if it'd even be legal.

 

Still, an interesting thought.

[calbiterol]

My guess would be both amazingly expensive and amazingly difficult - not to mention that I don't think they even make carbon nanotube "sheets" anywhere near that large, even in research labs. But composite, carbon fiber, etc, might also be agood bet - but it's probably going to be heavier anyway. Go with whatever is lightest and still strong enough to stand trials.

[Illuminati]

http://www.msnbc.msn.com/id/8976160/

Although still expensive, they've been able to churn these out at several meters a minute.

Heh, just a little speculation thrown out there.

[calbiterol]

Wow. First useful thing I've learned all semester.

[Illuminati]

Oh yea!

 

I forgot to update.

 

Ok, so the first competition was last week, umm... We bombed it...

 

Kind of a bummer, but then again, I hadn't studied at all for any of my events, I was concentrating on my plane far too much, which by the way, sucked as well.

 

I was forced to use a kit that Eberly (my instructor) had had for about 3 years, and guess what! It flew for a total of 9.8 seconds! Woot!

 

But I suppose that's what I get for testing it the day of the competition.

 

Oh well, I'll do better for the next competition next weekend with a better kit. And then for the big competition in 5 weeks, I'll have the super design that I was given by one of the judges.

 

So, yea, I'll probably send you guys some images when that all gets done.