...sky ray tips...

[Bootlegger]

  Guy's I looked for some tips to build a sky ray, all I saw was carrier stuff.
 I am looking to build one stock, but instead of the plywood ribs I'll be using 3/32" balsa for all ribs, also using 1/16" ply for the engine doublers as I plan to fly with an OS 20 or 25.
  Any suggestions will be greatfully appreciated.....

[Larry Fulwider]

http://www.clstunt.com/htdocs/dc/dcboard.php?az=show_topic&forum=103&topic_id=198043&mesg_id=198043&listing_type=search

Brett tells it all in one place

Larry Fulwider

[Clancy Arnold]

Gil
One thing to look at is the bellcrank mounting.

It is a piece of 1/8 plywood setting on two ribs ONLY.  It is only locked to one rib.
Mine failed pull test at about 20 lbs.  That was using the plywood ribs.

I redesigned it larger to reach across three ribs with all three ribs being locked in notches.  Then I put some vertical shear webs in to spread the load to the spars.

Now it passes the required pull test for Navy Carrier. 

Clancy

[Kim Mortimore]

Also on the bellcrank topic.  My experience with several Skyrays is that the controls tend to be sensitive, "twitchy", especially if the flyer has limited experience.  In general, it's good to have a range of adjustability on your control horn holes from "not sensitive enough" to "too sensitive," so that "just right" is somewhere in the middle (the Goldilocks principle  ).  My standard experience with Skyrays was to have the pushrod in the lowest horn hole and the thing was still too sensitive.  I couldn't hold it steady in level flight.   

Brett's combination of the outer bellcrank hole (stock SIG 3" with 2 holes) and a horn hole 1" below the hinges (that's a long horn) PLUS a wider 2" wide elevator may possibly give you a sensitive plane, with no room to reduce sensitivity.  Especially if your CG is not as far forward as Brett's.  7/8" is a well-forward CG.

For my 2 cents' worth, I would simply put the pushrod in the inner bellcrank hole if you're using the stock SIG 3-incher.  You can still make the plane as sensitive as Brett's setup if you want, by using a higher hole in the horn, and have a wider range of elevator travel adjustment.   

Hope you enjoy it.  It's a good plane.

Kim Mortimore

[Steve Holt]

Since you are going to cut new wing ribs anyway, I would cut then all to the pattern of the center section ribs then sheet the leading edge back to the spar.  This would eleminate the need for the half ribs.  On mine I used soft 3/32 sheet for the LE and capstrips since the center sheeting on the kit was 3/32 as was the TE sheeting.  The fuselage doublers were 1/16 plywood with a Brodak profile mount epoxyed in place.  This gives a 3 degree engine offset.  I used RSM landing gear from their Ringmaster kit to get a 2 wheel main gear.  For asphault takeoffs and landings I used a fairly long tailwheel strut (also from RSM) such that the fuselage C/L was parallel to the ground statically.  Like Dan, I used the 3 oz Hayes tank with muffler pressure.  With the FP20, 2 oz of fuel was near an overrun, so a 3 oz tank was plenty big.  Wing tips were stock outer shape with the inner portion removed so the outline was only 1/2" wide.  The tips were laminated from 3 pieces of 1/8 balsa with a strip missing from the center of the inboard tip for leadout clearance.  An adjustable leadout was glued to the inboard tip rib.  I put in a weight box, but it did not seem to need anything other that the 1/4 oz wt I started with.

The wing and tail were covered with Monokote and the fuselage was painted with Nelson paint.  As built this modified Skyray weighed 28 oz compared to 35 oz for my stock one.
Steve

[Bootlegger]

         Thanks guy's I appreciate the help and the suggestions..