Avistar wing....
08-14-2005, 09:07 PM
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Avistar wing....
So far in my attempt to remove the dihedral and add anhedral, all ive managed to do was cut the wing in two, now i'm stuck, and I have a few questions....
How should I glue the two halves together?
Does it need a brace?
fiberglass?
Do I need to trim the fuse?
etc?
Basically I just need some help, because I have no idea what im doing....
How should I glue the two halves together?
Does it need a brace?
fiberglass?
Do I need to trim the fuse?
etc?
Basically I just need some help, because I have no idea what im doing....
08-15-2005, 09:22 AM
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RE: Avistar wing....
First, a couple of questions ---
Why do you want to add anhedral, when zero dihedral works very well?
What do you mean by trimming the fuse?
To answer your questions --
Repair the inner ribs, if necessary, where you cut them appart.
Slot the ribs behind the old dihedral brace to accept a new 1/4 ply brace (straight, or otherwise) against the back of the old brace
Slot the ribs behind the leading edge spar to accept a 1/8 ply brace to be inserted against the back of the LE spar.
Epoxy the whole mess together, carefully aligning everything to get it straight (& flat, or whatever) -- don't use 5 min epoxy.
Make & insert balsa wedges to glue into the V-shaped gap at the end ribs (if necessary).
Cap the joint with 1/32 sheet (grain crosswise) to fit in the fuse between the wing saddles on the underside, & a similar width on the top side.
Recover & go flying -- with this mod you won't need to fiberglass the joint
Why do you want to add anhedral, when zero dihedral works very well?
What do you mean by trimming the fuse?
To answer your questions --
Repair the inner ribs, if necessary, where you cut them appart.
Slot the ribs behind the old dihedral brace to accept a new 1/4 ply brace (straight, or otherwise) against the back of the old brace
Slot the ribs behind the leading edge spar to accept a 1/8 ply brace to be inserted against the back of the LE spar.
Epoxy the whole mess together, carefully aligning everything to get it straight (& flat, or whatever) -- don't use 5 min epoxy.
Make & insert balsa wedges to glue into the V-shaped gap at the end ribs (if necessary).
Cap the joint with 1/32 sheet (grain crosswise) to fit in the fuse between the wing saddles on the underside, & a similar width on the top side.
Recover & go flying -- with this mod you won't need to fiberglass the joint
08-15-2005, 10:13 AM
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RE: Avistar wing....
I did this because I was bored, it was different, and I thought it looked cool. Besides, its just an avistar right?
Anyway, in addition to bracing it up, anything else I should do while my plane is ripped open?
Anyway, in addition to bracing it up, anything else I should do while my plane is ripped open?
08-15-2005, 11:27 AM
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RE: Avistar wing....
--- just an Avistar. I have had a number of Avistars over the years (I get mine on the cheap from bored students) -- great little planes -- not boring at all.
If you add anhedral, don't put in more than ~1 deg.
I would suggest that you put in dual aileron servos --- that will reduce the liklihood of flutter with those strip ailerons.
Increase the rudder & elevator area a bit by adding material to the trailing edges (don't go overboard).
Max the throws.
Use a good .46 for power (a TT Pro or OS FX/AX are good choices).
Close-in the nose to improve penetration.
Convert the wing to bolt-on.
Convert the LG to taildragger.
If you add anhedral, don't put in more than ~1 deg.
I would suggest that you put in dual aileron servos --- that will reduce the liklihood of flutter with those strip ailerons.
Increase the rudder & elevator area a bit by adding material to the trailing edges (don't go overboard).
Max the throws.
Use a good .46 for power (a TT Pro or OS FX/AX are good choices).
Close-in the nose to improve penetration.
Convert the wing to bolt-on.
Convert the LG to taildragger.
08-15-2005, 03:03 PM
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RE: Avistar wing....
Here are a couple of nose-jobs. The Superstar has a home-grown bolt-on wing. Those are full-house nose jobs, but you can make simple balsa or plastic fill-ins on the existing "cheek" noses.
The bolt-on thingy is done by inserting & glueing a 1/4" dowel in the leading edge of the wing on the mid-line -- it slides into a re-inforced hole that you drill in the bulkhead at the "head" of the wing saddle. The trailing edge is held down by bolting through a ply re-inforcing pad, glued onto the trailing edge area above the rear of the wing saddle. The 1/4-20 nylon hold-down bolts screw into tapped holes in hardwood blocks that are glued & screwed to the fuse sides & wing-saddle rear bulkhead, beneath the bolt holes.
The bolt-on thingy is done by inserting & glueing a 1/4" dowel in the leading edge of the wing on the mid-line -- it slides into a re-inforced hole that you drill in the bulkhead at the "head" of the wing saddle. The trailing edge is held down by bolting through a ply re-inforcing pad, glued onto the trailing edge area above the rear of the wing saddle. The 1/4-20 nylon hold-down bolts screw into tapped holes in hardwood blocks that are glued & screwed to the fuse sides & wing-saddle rear bulkhead, beneath the bolt holes.
08-15-2005, 05:12 PM
#9
RE: Avistar wing....
Built stock, the Avistar will roll in the direction of rudder. With a flat wing it will still roll in the direction of rudder. You need 3 degrees of anhedral on each side to counter the roll. Either that or downward end plates extending about 3/4 inch below the wing and flush on top. 3 degrees is right at 1.5 inches on each side of 3 inches total anhedral.
If you have too much anhedral, the plane will roll opposite to the rudder, right rudder, left roll. It takes a lot of anhedral to get a big roll. Normally, you have to put in rudder and hold it to see the roll. If there is too much anhedral, when you enter knife edge, the plane will try to roll inverted instead of rolling out.
Here is a photo of my engine break-in Big Stick 40 with an OS .50SX I am breaking in. It has the dihedral brace reversed to give anhedral. It isn't enough and the plane still rolls out of knife edge. One of these days, I'll cut the "Stick" style tips off and put some plates on.
If you have too much anhedral, the plane will roll opposite to the rudder, right rudder, left roll. It takes a lot of anhedral to get a big roll. Normally, you have to put in rudder and hold it to see the roll. If there is too much anhedral, when you enter knife edge, the plane will try to roll inverted instead of rolling out.
Here is a photo of my engine break-in Big Stick 40 with an OS .50SX I am breaking in. It has the dihedral brace reversed to give anhedral. It isn't enough and the plane still rolls out of knife edge. One of these days, I'll cut the "Stick" style tips off and put some plates on.
