2m glider

[hello183]

I am designing a new glider and I just want to post my progress on the plans now. These are some of the things I am hoping for it to have
pod and boom
hexagon fuselage
2 channel (maybe 3 if I want to add spoilers.)
2 piece wing
ag35 or ag36
fishing line pull system (springs on the control surfaces will pull it the other way.)
I was also thinking about making the control strings internally guided in the boom.
The first image is the pod and some of its formers. The second is a top view of the pod

 

[quorneng]

Interesting design!
A glider is all about the wing. I design and tend to make that first.
Then design the fuselage to have a small a cross section and be as streamlined as possible.
Nothing wrong with a pod and boom layout although I am not keen on spring return control surfaces. It means the servo has to be man enough to handle the extra pull load.
Keep posting.

 

[hello183]

I'm thinking about gull wings

 

[danskis]

Nice project. Competition 2 meter gliders often use pull strings and yes, as quorneng says, the servos need to be able to hold up under the constant load of the springs. So make your servos are accessible if you have to replace them. The "string" is the plastic wrapped wire used for stringing beads and you can find it at any craft shop. The only reason to run the strings through guides is to keep it from sawing away a notch in a bulkhead and then getting wedged and not being able to move.

It's a built up balsa boom or a fiberglass boom?

And how's the old glider working?

 

[hello183]

it will be a balsa boom. The other glider flies very well, like it could stay up for minutes with a light toss. But it is so light that I have to wait until there is no wind before I can use it. I'm thinking about making this glider heavier, so the wind won't affect it as much.

 

[Inq]

Competition 2 meter gliders often use pull strings and yes, as quorneng says, the servos need to be able to hold up under the constant load of the springs. So make your servos are accessible if you have to replace them.

Or... just use strings on both sides and use a spring just to keep tension in the loop. That way you don't have a constant load (and current drain) on the servo AND you won't have to judge how strong a spring it might need to resist the aerodynamic loads... say in a dive when it's critical. At the very least... put a single string design pulling the elevator up.

I'm using Dynema or P.E. braided fishing line. Light - it floats. Soft - tighter bends than monofilament. Coated - for near frictionless through guides. Strong - The six pound test is about the thickness of human hair. All things fisherman expect.

 

[Tench745]

Like Inq says, you want the pull string to pull the elevator up and the spring to pull it down.
On my glider I have a spring-pull elevator and I made up a little torsion spring that fits under the control arm on the servo to help resist the spring on the elevator.

 

[danskis]

Since you want it a little heavier you might consider making at least part of the boom out of 1/16 sheet balsa to simplify the construction. Perhaps make the sides out of sheet and join them together with bulkheads or 1/16 square joiners.

BTW - how are you going to get it up in the air?

 

[Bricks]

What would be wrong with a pull pull system? Braided fishing line would work you would have to watch how you connect it as it is slippery and some knots do not hold well.

 

[Inq]

What would be wrong with a pull pull system? Braided fishing line would work you would have to watch how you connect it as it is slippery and some knots do not hold well.

Yes, that is correct. You have to use good knots! Fishermen have very little trouble... or they'd lose a lot of fish. And I can assure you a Bass will pull far harder than that elevator ever will.

 

[Bricks]

Yes, that is correct. You have to use good knots! Fishermen have very little trouble... or they'd lose a lot of fish. And I can assure you a Bass will pull far harder than that elevator ever will.

Could not tell you as I am Walleye and Crappie fisherman.

 

[hello183]

I was thinking about sheeting the top side of the boom with 1/16 balsa and doing trusses around the bottom. The sheeting was mostly because the wings will mount onto the sides of the fuselage, and I need some sheeting there so it is easier for the covering to transfer between the fuselage and wing roots. Also I might do a pull pull system instead, the reason I didn't want to is that there are more strings, and it seems more complicated.

 

[Piotrsko]

Everybody talikng fishing line fails to mention stretch. Don't do you no good at all if the line stretches instead of moves the surface. I'm using some 50lb test line that does stretch, but not until over 20lbs.

@hello183 .sounds like your plans are pretty functional. Keep it up

 

[danskis]

1/16 sheeting is a good idea. Beading wire and beading wire crimps, used to string beads, are commonly used on discuss launch gliders and other high performance gliders. Easy to use (no knots), cheap, doesn't ever stretch and commonly available at all "hobby" shops such as Michaels.

 

[Bricks]

Everybody talikng fishing line fails to mention stretch. Don't do you no good at all if the line stretches instead of moves the surface. I'm using some 50lb test line that does stretch, but not until over 20lbs.

@hello183 .sounds like your plans are pretty functional. Keep it up

Use braid it has zero stretch that is what I use..

 

[quorneng]

On lightweight foamies the stretch of monofilament lines is not a problem. Just put some tension in, about 10% of the line breaking strain.
The pull/pull set up will have absolutely no slop even if the geometry is not perfect over the full servo travel.
Monofilament is incredibly "slippery" so you can get away with the line running over the surface of the fuselage as well.
In addition the fact there is still more "give" available in the line will probably save the servo gears in a hard "arrival".
Works for me but only in truly light weighs.

 

[hello183]

I am thinking about using a tube in the wing that slides into a bigger tube in the fuselage and bullet connectors by the trailing edge to hold the wing. What do you guys do when you need to make wing joiners for this sort of thing?

 

[danskis]

That sounds like a good plan. I wish I could point you to a place to buy what you need but I've only built that type of wing in a kit where the hardware was provided. I'm curious to see what others recommend. You can also use magnets or painters tape to hold the wings on.

see if you can find something here:

Amazon.com : 4mm i d carbon fiber tube

 

[Piotrsko]

Im a fan of brass tube and 1/4" music wire spars but arrow shafts and carbon fiber inserts work well also

 

[hello183]

I'm thinking about foam cutting the half of the wing in front of the spar, for durability. Are there any iron on coverings that are lightweight and can be used on foam without melting/distorting it?