retract help
 

[:o]Ok guys, I need a little refresher course in retract installation. I have not built a pattern plane in a long...long time. I have a Vertigo II that I found buried amoungst a lot of junk in my attic. It has been a while since I have seen anybody fly one of these kind of birds. Everyone is into the 3D thing...
Anyway, this one is of classic design manufactured by Skyglass and I guess it was produced in the mid 70's. Foam wings and stab, glass fuselage with fin molded in, and a set of prints.... thats it.
My question is:
The rhom-air retracts were originally powered with a FREON cannister (obviously pre-EPA) and it was rather small. I do have a set of rhom-air 3 gear retracts, but the controls and air tank are a Robart setup. I am trying to find a good place to put the air tank (which is considerably larger than the rohm-air). I am thinking up into the canopy area with a big glob of silicone.... but I am open to ideas.
Another question would be:.. I used to use Sorgam (sp?) to glue the sheeting to the foam. Anything new work better? This wing format has no hard leading edge, just sheeting wrapped around the foam. It does, however have a hard trailing edge, presumably to hold the hinges.
Any Suggestions?.... anyone familiar with the Vertigo II?

Thanks...
CC

RE: retract help
 

Here are some helpful links for you:

Rom-air retract install (I like them the best of all):

http://www.rcuniverse.com/forum/m_2434444/tm.htm

Wing sheeting and leading edge solution:

http://www.rcuniverse.com/forum/m_3092876/tm.htm

Spring Air retract install:

http://www.rcuniverse.com/forum/m_2827386/tm.htm

RE: retract help
 

Thanks 8178... the old brain is starting to warm up. there is some really good info in your links. One question, you dont add support to the retracts in the foam wing? I was under the impression that the retract will tear out of foam without additional support. Maybe I have been overbuilding (and adding weight). I do fly off of asphalt (read that road, with a curve no less. take off and turn right as you lift off or a plane eating fence and a big hill will do you in). I used to add a couple of 1/8 ply ribs epoxied to the retract mount.(chordwise).... too much engineering?
thanks,
CC

RE: retract help
 

I’ve never had any problems with the mount but I did add an extra dowel down into the wing on the Kwik Fli III. I usually fly off blacktop but have flown of grass a few times.

RE: retract help
 

Corsair,

Usually you will make a 1/8" plywood plate for the gear to mount on and then put 4 3/16" dowels about 1" long into this plate and countersink the plate and drill holes for the dowels in the foam wing. This makes the gear almost bulletproof from pulling out. I will see if I don't have a picture of this somewhere and upload it later... but if you have any questions, this is certainly the right place to ask.

Dan

Carolina Custom Aircraft

RE: retract help
 

You'd also recess the plywood plate far enough so that you can add a layer of balsa to sand even with the contour of the wing's lower surface. You'd leave just enough exposed for the retract unit.

Some modelers would just lay in a 3" x 3" piece of 1/4" ply. The large area of the plate also kept the gears from pulling out. Just cut away enough for the gear unit and the leg. Was heavy, though, but many models of the time were a bit heavy. Many Pattern planes of the time weighed 7-1/2 to 8-1/2 pounds. The Mach I was considered "ideal" at about 8 pounds. The mass helped hold speed in the vertical maneuvers.

RE: retract help
 

I have always used the ply plate + dowel method referenced above, but I put RTV (silicone) into the holes in the foam core for the dowels. That way, if there is some flexing in the ply plate the dowels won't widen the holes in the foam. The RTV acts a bit like a shock absorber. I fly off of grass and this has worked well for 2 Deceptions, 1 Tipo, 1 Escape, and 1 Pursuit 120. The gear will bend before the plate pulls out. In fact, with the Rhom gear legs I have to periodically rebend them slightly.