INPUT NEEDED: Making a home-made hang glider (Yes you can help)

My friends and I are devising a plan for a competition called Flügtag, which I will not advertise here.

Basically we are going to try to make a hang glider, ride a bike with it, and then lift off with the speed.

This thing doesn't have to go too far (20 feet would be sweet), we just want it to be successful.

Here is a model I made this morning at about 12:1 scale. We are probably going with the "Rotello Wing" model:



Now the question is... what do we make this thing out of?

What should we use for the solid frame... PVC piping? Some type of wooden dowelling? Or metal rods? (we have no experience with cutting metal though so that could be hard)

And then the sail part itself. Tarp? Clear plastic sheeting? Cardboard?

Cheapness is a priority, as we are college students and this will probably end in failure anyway.

How will we attach the frame together, and then how will we attach the sail to the frame?

I am also worried that it may not actually lift a person, since theoretically this model should be able to lift 15 pounds by my calculations, and it would definately snap. I assume (or hope) the correlation between size and weight capacity isn't linear though.

Any other input or criticism would be appreciated. We have no idea about "Angle of attack" "Stabilizers", "Lift", etc.

Basically... help me look like an idiot, and soar across a park with a giant paper airplane.

[edit on 14-4-2006 by Yarcofin]

As usual, the disclaimer....I am not an aeronautical engineer.

First, recognize that the model will not lift or glide 15 lbs., judging by the scale established by your hand. Also, It is doubtful an average person pedaling a bicycle, can achieve the necessary speed to achieve "lift". O.K., I looked up the competition...speed isn't an issue.

Your frame looks too rigid to attain an aerofoil shape, necessary for lift. I would suggest attempting to duplicate the classic hanglider form factor.

PVC is probably the easiest for non-mechanical persons to work with. A hacksaw and some PVC cement is all it takes. The problem with PVC will be attaching parts together at angles other than 90 deg. or 45 deg.

I'd suggest heavy, plastic sheeting for the 'skin' material. And duct tape. Put the material on the bottom of the frame and use the airflow to 'push' the material against the frame. Know what I mean?

I hope this helps and is not completely wrong. I'm kind of confident in it. It is late on a Friday night afterall.

NC

[edit on 14-4-2006 by NotClever]

I recommend you make it out of nylon. Use aluminum tubing connected with U-bolts. You need the 2 leading edges, 1 down the middle, and 1 going across. Eliminate all the others, they only add weight. Fold the cloth over and sew at the leading edges. Cut a strip for the center rod and sew it down the middle. The only points the nylon has to contact the aluminum is down the center and on the leading edge. The nylon will bow upwards, giving the airfoil shape which will provide lift.
Remember to provide guy wires from below to the ends of the center cross support. You also should provide a mast up the center and install guy wires going down to the ends of the center cross support.
The 3 long aluminum tubes (2 leading edge, 1 center) should be about 10-12 feet long to provide any meaningful lift. It should support a bicycle and rider without a problem.
Always remember to take pics and post them back here so we all know how you did!

Good luck!

Just wanted to add:
Guy wires from below to the ends of the 3 tubes will allow you to use smaller diameter tubing which will reduce cost just a bit.

Thanks for the input so far guys.

Yeah, the finished product is going to have a wingspan of 15 feet if I use an "inch to foot" proportion. About half the size of a commerically available glider.

So it's going to be stable enough with only those 4 bars? Okay... saves a lot of material and work anyway .

I don't exactly understand how to attach guy wires, or what their purpose is. Can you go into some more detail about this?

Not surprisingly, very few people have attempted to build their own hang glider without the use of a kit before. So there is not much information on the Net. This is the clearest diagram I've found so far:

Image Source: Howstuffworks.com

How does the tension of guy wires create more strength or stability? Or are they simply for the sake of steering? I see how the top guy wires go to the ends of the leading edges, and the guy wires below go to the cross-bars. But I still don't understand what purpose they serve, or the best way to attach them.

Also remember at all times that I just want to glide across a park. The world Flugtag record is less than 30 metres. I don't want to accidentally build something overly-powerful and get stuck in the air for three hours .

[edit on 15-4-2006 by Yarcofin]

I can't imagine that PVC pipe would be rigid enough in this application. I mean a 15 foot length becomes really, really flexible.

The wires add rigidity to the tubing so you don't have to overbuild. The wires shown in your drawing are what I was talking about.
I just think there should be 3 more wires from the bottom to the "back ends" of your aluminum pipe to keep them from bending upward.

What gauge of wires are we talking about here? I assume that just any flexible metal wire will work.... pull it tight and drill some holes in the frame to tie it onto, right?

What do you guys make of the "battens" in the HowStuffWorks diagram? Do you think they are necessary to have a working hang glider? Apparently they add more rigidity to the sail or something. But I don't know what I would make those out of either.

And yeah of course if this works and we ever actually get it finished, there are going to be videos and pictures galore.

You're right, any thin strong wire should do the trick.
I think the battens are a recent addition to hang gliding. I'd leave them out, you just want to take a short trip and go collect your prize money, right? No reason to add too much complexity to the thing.

Look! Up in the sky, it's a UFO! No, that's not it!

It's a Seagull! No, that's not it, either!

It's a hang glider! Yes!!

Be careful, be safe!

Good luck with the project!

PVC tubing is extemely flexible in the cold water grades.
The better grades - including electrical conduit is also too flexible to use in aircraft.

Instead of re-inventing the wheel, why not copy an existing Rogallo hang glider?

Here's one look at a Rogallo: en.wikipedia.org...

Once you get the aluminum tubing you need, you could order splice T's and the like from the hang glider kit companies.
Assembling things with JB Weld - an excellent metal epoxy adhesive - would work well.

There are other alloy specific adhesives out there, but JB works well in most areas.
I've combined aluminum fuel line fittings with JB so as to make a fitting that isn't available.

The interesting part of this engineering exercise will be setting it up so the bike is steerable when running in ground mode and the wing's control bar is operable when in flight.
Combining the two controls in some way would help to alleviate the weight problem.

Using a very lightweight bike to start with would be a given.
You should be able to find a lightweight 10 speed road bike out there, used, not too expensive and use that in lieu of a heavier mountain bike.

You've probably thought it out, but using a subtle and seldom used by auto's modest downgrade would be a good way to go for the "taxi" tests and the very low level liftoff testing that would be required prior to flight at any altitude over 3'-5' or so.

One thing you do want to incorporate is an adjustable hanger system that would allow fore and aft CG changes with ease.
A simple strap with multiple holes drilled within and welded to the framework along with a "pit pin" as used in race cars or a bolt of proper strength with nylock nut would make CG changes easy.

Use care here, I read about one home-made hang glider where the builder used cheap dime store bolts to support his weight and when the bolt broke, the CG change was tremendous and he rode a fluttering piece of nylon to his death.

Follow the lead of aircraft manufacturers.
Use adequate strength materials and do not settle for sloppy workmanship.

Uttering "Uh Oh" at 3000' is no fun....

Thanks for the added input Desert Dawg.

Just a few things:

We actually intended to use the Rogollo wing, but I simply misinterpreted the drawing as there were no actual blueprints or instructions. I came across that very article in my initial research.

I don't want to deal with hang glider kit companies. That would make it look like an actually serious, professional project. Everything I buy is coming from Home Hardware .

We had an original intention of stabilizing the bike's front handle bar so that the wheel couldn't turn, you only go in a straight line. But as long as the hang glider isn't too tough to hold, I think we can just use a normal bike. The weight of the bike is irrelevant, since we have no plans to lift the bike. It will just be dropped when we get enough lift. So it doesn't matter if it's a kid's bike or a mountain bike.

One thing you do want to incorporate is an adjustable hanger system that would allow fore and aft CG changes with ease.
A simple strap with multiple holes drilled within and welded to the framework along with a "pit pin" as used in race cars or a bolt of proper strength with nylock nut would make CG changes easy.

I must admit, I don't really have a clue what you said . What's a CG change? I assume central gravity. So are you talking about the control bar that the pilot holds onto? Make that adjustable up and down the main vertical bar (keel)?

As for cheap dimestore parts.... if anything kills us, it's going to be our lack of aerodynamic design understanding, inability to fly a hang glider, and incorrect building rather than the parts themselves. We are probably never going to lift higher than 10 feet anyways though, so I don't think that's a problem. Maybe break a leg in the absolute worst scenario. Since we're in a field/park the landing should be pretty soft anyway.

Unfortunately I have exams all next week so the hangglider project will be put on hold and not started until my friends and I are done our college semester. So it will only be in my dreams for a while. I'll get back to you with more updates when we start again .

[edit on 21-4-2006 by Yarcofin]

You need to get your center of gravity in linewith your center of lift, otherwise it could become a very unstable craft if it is too tail heavy. There is a formula for figuring out your center of lift (cant remember what it is off hand). Do you have a full line hobby shop near you that has a large radio control airplane dept.? If so get with some of the guys in a local RC plane club, most of those guys understand aerodynamics extremly well.

Look up in the sky, its a bird...

No its a plane...

No its Yarcofin!!

Yeah, laugh if you will. But this is what happened when my friend came over and we attempted to create a larger, more complex wooden glider prototype. It more-or-less worked, but it didn't glide. This is what was left. We were moderately upset with it.

One thing that has been noticed is that we simply cannot make it without improvising. In the first case, I used excessive amounts of glue to hold the glider together. And in this case, we traded in screws halfway through for a handy staplegun.

THE PROBLEM:

We cannot get the crossbar and leading edges attached in an efficient and strong manner. We have to screw the "crossbar" on top of the "keel". But then it is on a different level than the "leading edge tubes", and creates tension to pull apart when you try to attach the two. One option would be to have four shorter bars for the crossbar and keel, and then attach them all at one joint in the middle, but that would not be as strong. Also just in general, we don't know how we are going to attach the three pieces in the front. Any help or diagrams would be lovely.

The fact that we bought a kite, and the stupid thing couldn't even fly straight when it was manufactured by an actual company threw off our confidence as well. (It would always pull to the right and straight into the ground, so that we couldn't fly it for more than 30 seconds at a time). I don't know if observing the kite helped us, or threw us off even more.

Also, do we need to attach the fabric to the keel, and how. Or is wrapping it around the leading edges good enough?

[edit on 3-5-2006 by Yarcofin]

I would take the cloth and fold it over and sew it for the leading edges. Double-sew it just to be sure.
To join the 3 pipes at the front I would take a bolt that is long enough and bend it into a slight "U" shape. that way you could drill the holes straight through the pipes.
If you want to get fancy, just drill the pipes at an angle so you can use a straight bolt through the 3 pipes.

Where is this competition being held? I sure would like to give it a try.....

Center of lift - or as it's called in the sailboat world, center of pressure can be found by the following.

Plot a scaled outline on a piece of paper.
Graph paper works well.

For a square, run a line from top left corner to bottom right corner.
Run another line from top right corner to bottom left corner.
Where the lines intersect is the center of pressure for a square.

For a triangle - which is the usual shape for a modern Marconi rig sailboat as well as the Rogallo wing;
Run a line from each corner to the middle of the opposite edge.
Three lines in total.
Where they intersect will be center of pressure.

To get the center of pressure for a two sail, sailboat - like a sloop or cutter - you'll need a side view of the boat's sail plan scaled out as above.
Find the center of pressure for each sail.
Draw a straight line between each sail's center of pressure.
The center of pressure is exactly between the two sails centers of pressure if the sails are of equal size regardless of whether there is overlap or not.
If the sails are of differing area, a percentage factor is involved, but I can't remember the precise details on that.

Be that as it may, not a problem for you since you're dealing with only one sail/wing.

You'll need to do some research on CG vs CL (Center of Gravity vs Center of Lift) but the basics are the CG needs to be slightly ahead of the CL.
Slightly nose heavy is always safer than slightly - or worse - tail heavy.

With the CG ahead of CL the horizontal stabilizer - if of sufficient size - is powerful enough to overcome the nose heaviness of the aircraft.
Get the CG far enough aft and the stablizer won't have enough power to overcome the tail heavy situation.

Since the Rogallo is in effect a flying wing, the whole area is involved with pitch changes, but if the CG is aft you'll run into the same situation as a standard airplane will with separate wing and horizontal stabilizer.

I'm sure there are some Rogallo wing sites on the Internet that will tell you where the CG should be as compared to CL.

As far as building techniques go, have you given any thought to utilizing modern epoxies in areas where they could be used?
There are alloy specific epoxies out there - available through machinist supply houses like MSC - but good old standard JB Weld will work just fine.

Slip fit tubing and purpose made brackets of thin wall aluminum tubing would do the job.

Originally posted by Yarcofin

I don't exactly understand how to attach guy wires, or what their purpose is. Can you go into some more detail about this?

The wires give the hanglider stress-stability, flight stability and steering possibility next a clever and simple assembling and dissasembling concept. The joint above the 'steering triangle' is arrested but moveable for assembling and dissasembling.
The fire ensures the wing symetries (would be bad if one goes up more than the other) so they have to fit on each other. If you take a tube without the wires only it will bow upward on the outside of the wing depending of the g forces and has impact of ithe wing form which is not wished for a hangglider. Also the tube alone without wires has to hold a lot of stress under g forces. Which can be too much and for it too handle. The wires is a cheap and stable concept to increase the force the construction can take. Its also used for bridghes and old planes.

Modern planes are build with good material that can take a lot of stress (bow) and do not need wires.

Originally posted by Yarcofin
Also remember at all times that I just want to glide across a park. The world Flugtag record is less than 30 metres. I don't want to accidentally build something overly-powerful and get stuck in the air for three hours

.

Hope you are aware that you want to do something every dangerous. As smaller your wing as more speed you will need for taking of and as more damage you will take when your wing does not fly stable enough and you crash!

there is a young fast upcomeing and somewhat dangerous sport where you sail on land with a wing. You can also 'misuse' this wing to jump hight and even fly if you are boring of life enough (serious warning here this IS a dangerous thing):

www.kitewing.com...
www.kitewing.com...

like you see in comperation with the skieing ppl he is is not that slow! (I would not like to do this with a bike)

The wing is a third of the wing size (area) of a hangglider handheld and uses no wire. www.kitewing.com...

oh byway..by useing a bike you will probabily have a problem of early take off when you want to do it on a flat ground. I mean you will not be able to build up speed first and then take off except you can somone pitch up and down the wing a little.

edit:
video added (added teh wrong one first)






[edit on 4-5-2006 by g210]