[JetGirl]

Hello,
I was wondering if anyone knows what a light weight but sturdy material might be for a EAP (experimental aviation project) I know that this isn't an aviation website but, there are alot of smart people here and i was just hoping to get some advice. The wingspan is around 7' by 3' ish and its about 3" thick, not inculding winglets.

[High Seas]

A few questions to get the end point parameters:
Wing Loading? (Thats a pretty low aspect ration planform).
Gmax +/-? - roll rates? (Again low AR)
moment about aerodynamic center?
Life Cycle -1 flight - years of service?
Use - one-off or commercial venture?
Its too soon for the RedBull tourny - getting started early? UAV project?

Maybe TPG - Taylor Paper Glass; maybe foam core with Fiberglass layup and bagged; maybe Carbon Fiber and RTM. - Just a couple of ideas.

FROM A CNC PERSPECTIVE:
The core and ribs (if used) as well as spar (or mould) shaping could be done on a cnc router then assembled/laid up. If a fabric wing form - could be cut using cnc and hotknife.

:cheers: Jim

BTW - Welcome aboard!

[JetGirl]

um...i am not quite sure what all that means, im a little green on mechanics...but it will carry about 174 lbs and i should be able to be use more than once and it is going to carry a live load so it has to be safe.... i was thinking carbon fiber over a aluminum frame but its iffy

[High Seas]

Ok - the the first thing I'd suggest - is take a look for Jack Lambie's Composite Aircraft Construction (Guide to - or something like that). Live load and composites are a "player" but at 21 sqft wing area that' 8 1/2 psf wing loading - at 1 g!
Just a few factors from one of the rigid wing sites:
http://www.aerosports.net/rigids.html
And, you'll note the "rocketman's" RedBull Get up is nominally the size you are talking about.
http://news.bbc.co.uk/media/images/3...93_baum300.jpg

So, is that why the handle "JetGirl"?
COULD BE A VERY INTERESTING PROJECT - ANd Not to be discouraging (take this from an OLD pilot*) do a quick read first see what you'd be getting in to. The mechanics of flight will bite you in the @ss every time. There is no forgiveness in hard earth and gravity.
* First Hang Glider Pilot in ND - 1972. First HG Crash in ND - 1972! Prol'y before you were born!

[JetGirl]

um yeah i have been looking in to that, and i am asking for help from a local university but, i dont know how things are going to work...and it is similar to Yves Rossy's project. Did you mean a 21 foot windspan for that much wieght? i'm confused. I will definetly look for that book. No worries i have thought ALOT about this and if it is worth it to risk a life trying this project and i am just going to see how it goes. By the way, thank you so much for the advice, it is really helpful even if it isn't always what i want to hear. If this is successful I will keep in mind that you gave me advice. : )

[High Seas]

No worries there
7ftx3ft= 21sqft wing area= wingspan x chord Wing area (SA)
Wing loading = SA/wt (All up -- includes your "live load" and the structure.
I've seen the book available pretty cheap = so keep looking.
As far as university help - see if you can get a student interested in the project - as an independent study - best if you can get them course credit too.
:cheers: Jim

[JetGirl]

right if forgot about that, and do you think that will produce enough lift to get that much wieght off the ground, i cant find the lift/weight/sq ft equation anywhere because I guess it depends on the project.

I have been contacting the U of U engineering department but they have been kind of sketchy about it. I know that Westminster (in Utah, sorry if you dont know what I am talking about) has a good aviation program so I might go there if things don't work out.

One other question, is there any special permits or licesnces that i need for somthing like this? (Private pilot?) And this isnt going to work if I dont get some kind of sponsor/support because there is NO way I can pay $80,000 dollars for jet engines, on the bright side, kerosene only costs 1.30 a gallon (now just if it weighed less......)

[CoAMarcus]

JetGirl,

I am a pilot and have been one since I was 18. Don't think that building a jet is something you can just jump into. Most people who fly jets have at least 1,000 hours in the cockpit of SEL airplanes before they even TOUCH the controls of a jet. Experimental airplanes are not something that should be taken lightly, and always treat a plane as if it is actively trying to kill you. If you ever get complacent with something going that fast it will not turn out well.

Read some aeronautical engineering textbooks. Look up what exactly makes an airplane fly, including understanding Bernoulli's principle and knowing why an airfoil creates lift. Read something aside from Wikipedia and go do a demo flight at your local flight school. The EAA has a "Young Eagles" program where you can go for a flight with a pilot mentor which you may want to look into. I suggest becoming a pilot before attempting to build an airplane.

Also, check out the AOPA forums. There are a lot of nice people on there that have a lot of useful information.

Marcus

[JerkyBoy]

Marcus,

What kind of plane do you pilot?

Did you build it yourself?

Please post pictures.

JerkyBoy

[CoAMarcus]

JerkyBoy,

I am certified in Cessna 172R, 172SP, 172RG, Cessna 182T Turbo, Piper Archer III and on the G1000 glass panel system. I prefer flying the 182T and the 172SP because the Archer III lands like a dumptruck no matter how softly you try because of ground effect with a low-wing airplane.

To avoid this thread from becoming a picture posting thread because I have so many, I will just put up one of my favorites. This is taken at dusk in Southern California near the San Bernardino area on the way back from Big Bear in IFR conditions (I no longer do IFR training because of lack of time to devote to it). We were vectored through the March ARB airspace and had to make a semi-steep bank to intercept the radial they put us on, which is why this is taken at essentially a 45 degree angle.

Marcus

[JerkyBoy]

Marcus

The G1000 must have been lit up all red during that flight.

That's a nice display, almost like a fish finder.

JerkyBoy

[CoAMarcus]

JerkyBoy,

I am certified in the G1000, but do not like it. I prefer the old analog instruments, so it doesn't feel like I am playing a video game. I flew the G1000 twice after certification and did not see a whole lot of an improvement over flying with the old instruments and I do not trust it in an emergency. Do you fly?

Marcus

[JetGirl]

thanks for the advice. i will definently look into that. people think i am getting in over my head...but thanks for believing

[svenakela]

...

Read some aeronautical engineering textbooks. Look up what exactly makes an airplane fly, including understanding Bernoulli's principle and knowing why an airfoil creates lift.

...

Marcus

Ah, finally something engineery in this thread.
Bernoulli's theories are a nice way to describe the physics behind the airfoil, but unfortunately it's a false truth that has been impossible to kill since ages. One of the chief designers behind the Swedish jet Saab Viggen even wrote a book about it trying to kill the myth about Bernoulli as a way to describe a wing.
Even though you may not read Swedish, here's a hand out from a university about laminar flow and linking, which it all is about.
http://www.mt.luth.se/~rikard/course...ng3/sld011.htm

Bernoulli's law is a fact, but in case of flying it's wrong facts.

Regards,
Sven
(also a pilot)

[dgapilot]

Bernoulli may not really be the way airfoils behave, but he does give us the ability to mathmatically model airfoils.

Jetgirl,
For some simple spreadsheets that will give you some basic idea if your project is feasable, try John Roncz's Excell spread sheets here ftp://ftp.xmission.com/pub/users/m/markm/roncz/dos/

All others,
Give me steam gages over a glass cockpit any day. While the glass is nice, for those of us that learned on the old instruments, the new ones take some getting used to. The first time I flew something with a G1000, it was about 1/2 hour before I figured out where the transponder was!

[CoAMarcus]

thanks for the advice. i will definently look into that. people think i am getting in over my head...but thanks for believing

Oh, you most definitely are getting in over your head. It is like trying to design an F1 racer without having ever driven a car: You can understand perfectly how it works in theory, but a single mistake in practice can kill you. It requires an almost anally retentive attention to detail to do something such as designing a machine meant to fly, much less something with a jet engine attached.

Sven,

I learned in my ground school that while they teach Bernoulli, there is a 50/50 split in the pilots that buy it. Like dgapilot said that while it may not be 100% applicable in this case, it does allow the design of airfoils to be much simpler. I'm just a dumb private pilot and not an aeronautical engineer so this is one of the rare cases that I have the attitude of "As long as it works...". I am content saying it is both Bernoulli and Newton's first law of physics as I was taught.

Marcus

[JetGirl]

thats excatly what i mean...but whatever i dont care what you think.

[svenakela]

I learned in my ground school that while they teach Bernoulli, there is a 50/50 split in the pilots that buy it. Like dgapilot said that while it may not be 100% applicable in this case, it does allow the design of airfoils to be much simpler. I'm just a dumb private pilot and not an aeronautical engineer so this is one of the rare cases that I have the attitude of "As long as it works...". I am content saying it is both Bernoulli and Newton's first law of physics as I was taught.

Marcus

Yes. And no.
It gives a simple way to express the aerodynamics, but it's still not the correct way and therefore it's wrong to teach pilots that Bernoulli's should be used for describing a wing. Actually, there's no reason for a pilot to know neither Bernoulli nor the physic laws behind air linking to learn flying. And even more - it's easier to understand linking than Bernoulli's laws of pressure. Designing a wing is all about creating as much linking as possible with the least resistance as possible. Bernoulli can tell what's happening around the surface of the wing, but not why it actually flies.
How many with a driving license can describe a four stroke engine? They can still drive though.

[PhillipM]

Well, I don't know whether you can call 95% of what you see on the roads 'driving', absentmindely steering perhaps, but...

[CoAMarcus]

Bernoulli can tell what's happening around the surface of the wing, but not why it actually flies.
How many with a driving license can describe a four stroke engine? They can still drive though.

Sven,

I agree, but Bernoulli does help clear many things up by providing the details about what is happening around the wing. Knowing about Bernoulli provides easier understanding of wake turbulence and wingtip vortices. The reason that you don't need to know much about a four stroke engine in a car but it is vital in a plane is the extra dimension: If you have an engine fail on the road you pull over until you can figure it out, but in a plane you have to make a decision if it is possible to restart before you hit the ground.

How do you explain an airfoil creating lift if not through Bernoulli or Newton? This is one of those things we talked about in ground school and I have never really touched on since, so I am genuinely curious.

Phillip,

While not perfect myself, I have seen some people that should not be behind the controls of a plane. One such incident was on Catalina Island off the coast of California where a guy flew the pattern backwards and I and one other plane had to leave the pattern so nothing happened. The other incident was a guy flying about 270 degrees at 3500MSL while I was going 90 degrees at 3500MSL and talking to ATC. I got the "Immediate action required" call from them and dove 500 feet real quick just to see the guy pass off the right wing about a quarter mile off. But, you know, I am sure even astronauts have their off days...

Marcus