FMK Ripster

[Bob Cotsford]

anyone know of this 80's (?) kit?  It's a 30" sport model for .049-20 engines!  It's got a swept back shoulder wing and simple lines, wings are brown paper/pva covered, no veneer, though it recommends veneering them or adding a 3/16 ply spar for a .20. 

I'll try to get a photo of the box tonight.  I picked it up at the club bring'n'buy the other week, so far the fuselage has gone together while watching Dr Who, just a simple box - maybe too simple! 1/8" sheet sides, two formers and  a couple of cross braces, 1/16" top and bottom.   All sheet tail has been sanded ready to fit, but I need to sort something out at the front end.  it's designed with a 1/8" ply former glued directly to 1/8 balsa sides, no doublers, just triangular section bracing.  No doubler under the wing either, the wing bolts on to 1/8 ply plates front and rear - again the mounting plates glue straight to the balsa sides.

Would an epoxy and glass finish be too heavy for a small model like this - I've never tried a full epoxy covering job before so have no idea how much weight it adds.  I'm certainly tempted to do it for the wing.

Another evening could see it ready for covering at this rate, unless I go to town adding doublers (and weight!) around the engine bulkhead and wing mounts.  That would make it two evenings

[StarLoc FiveStar Adhesives]

It doesnt need any strengthening, strong enough as it is,  although it says to add a spar for a .20 , i didnt most times but you could break the wings with something like an irvine20 pylon rapid pull out from a full power dive, a std 20 was fine without the spar , it was just as a cover for insurance to say to fit it, we never fitted veneer on them apart from one model with an os40, the front needs no further reinforcement , just a bit of balsa behind the front bulk head

Realisticaly though i would put it on a .10 or something like that and check the aileron rates are low, another thing people always want to do is change the wing incedence , it should be lower at the front , this looks like neg incedence but actualy puts the wing closer to 0 deg , due to the flat wing section , allowing the model to fly inverted with flat section

 

[Bob Cotsford]

Wow - somebody has been trawling the old threads!  I had a lot of fun with the Ripster, note the 'had'.  In the end I covered the wing with 1/2 oz glass PVA'd  on, and the fuselage with glass cloth and water based varnish.  With a 300W electric setup it was a bit of a giggle (nervous hysteria I think) with non-stop vertical twinkle rolls as far as vision allowed, yet very stable upright and inverted.

It met it's end when it stopped responding in a power on dive, the wing and tail survived unscathed but the fuselage was matchsticks as the motor was about 4" deep in the earth.

 

OS40?  That really is the definition of insanity.