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        Build Log efflux RC/Air Sally....F-20, 70mm ALL COMPOSITE w/custom ducts

#1 efflux RC Apr 21, 2010 12:00 AM

efflux RC/Air Sally....F-20, 70mm ALL COMPOSITE w/custom ducts
6 Attachment(s)
Here's a project that we hope you folks will enjoy, and want to add this one your hangar.

Our 70mm, F-20 is 100% epoxy/glass construction. (Fuse, wings, vertical stab, tailerons)
It is a very light lay up, with all the fiberglass and cockpit/canopy parts (without formers or other items) weighing just 1lb 4.5oz.

...EDF size: 70mm
...Wing Span :860mm (33.9")
...Length :1180mm (46.5")

We are working in conjuction with Air Sally to build two flying prototypes, to explore the feasablity of offering the kits with optional full composite inlet ducting. The ducting to EDF transition will such, as to allow fitment of your favorite 70mm EDF/motor combo.
Additional scale and structrural considerations will be made along the way.
Including the fitment of retracts. Some of the possiblities are currently being considered and will be discussed later. As we are just beginning the discovery process of the current configuration, Air Sally has received his unit for examination and modification today.
One of the fist two protoypes will be built and flown by Air Sally and Corsair Nut. The other will be built by efflux RC and flown by usmc_VTOL_mech.

As our usual practice, Videos will be produced of both jets and full specs of the "as built" units will be provided.
At this point, only one thing is definate. They both be very fast.:)

You'r invited follow along, and share your comments and ideas.


#2 AIR SALLY Apr 21, 2010 01:58 AM

hey Gary can you post the manual here too to help us show what we are doing .

#3 pilotrcuk Apr 21, 2010 02:01 AM

Guys, this airframe looks terrific and I'll be watching what you're both doing re the build. I've been moaning about 70mm stuff only being available in heavy, brittle polyester for some time now, so something like this really appeals, particularly for a lighter setup as AS has discussed.

Would be great if Skyworld were coming out with more airframes like this...

#4 lavochkin Apr 21, 2010 02:03 AM

The fuse appears to be built like my Jepe Pyranha. Light and thin.

#5 AIR SALLY Apr 21, 2010 02:14 AM

they did the lightest layup i have ever seen ...they soaked up all the excess resin too . it might be too light for big power but i'll show how to fix it;)

#6 lavochkin Apr 21, 2010 02:22 AM

That is how the pyranha's are. They need some internal reinforcements. No biggie. Are the wings as thin as the pyranha's too?? Mine are like 1/4" at the thickest and that is glassed with 2oz. glass cloth.

#7 efflux RC Apr 21, 2010 03:47 AM

1 Attachment(s)
Here's the manual Rodger. I'll break out all the photos and post them individually later.

#8 jayb1rdz Apr 21, 2010 07:18 AM

L - Wings are thin like the Piranha and all composite. I have a spare Phoenix wing that might be modified for the f-20 as well....... but then retracts wouldn't be possible.

Gary, you are right....I missed both ring pieces in my Kit. I hope they are not necessary with the mods.

A/S I am not sure if you saw the picture I posted of my F-20 damaged wing. A crease in the starboard wing top skin from LE to TE. Any suggestion on how to repair would be welcome.

By the way.......... love this thread already.

#9 AIR SALLY Apr 21, 2010 11:20 AM

jay i hav'nt seen the pic .mine has a few blisters or disbond of the gel coat...i'll show how to fix that.
Joe the wing are nice and stiff,there looks to be 2 spars inside ,maybe .400" thick .

#10 St. Martin Apr 21, 2010 02:15 PM


Originally Posted by efflux RC (Post 14905653)
One of the fist two protoypes will be built and flown by Air Sally and Corsair Nut.

I can see Roger doing this. But Brent(CN)? He hates F-20's:rolleyes:


#11 AIR SALLY Apr 21, 2010 02:44 PM

Fiber glass mod
6 Attachment(s)
Heres some pics of how i reinforced the fuse with 5 pieces of 5.8 oz. glass cloth

#12 efflux RC Apr 21, 2010 03:15 PM

Looking good Rodger.:) you better put an extra layer on mine. :p
I thought you were gonna start with the ducts.

oh ooh...Why didn't I sent ya both of 'em ? I'll fix that!

#13 AIR SALLY Apr 21, 2010 04:41 PM

well i needed to do this first so i would'nt cause damage while i'm doing the ducts . next im going to mock up where the fan will mount...so we can have a good idea where it will go ,and still have good CoG.
this mod took about 45 mins to do ,used less than an 1 1/2 oz. of epoxy and only about 2 oz. of cloth.i soaked up excess resin with tissue paper after i brushed on the epoxy .should add strength to the fan mount area the nose for speed and possiable nose gear landing loads.

#14 efflux RC Apr 21, 2010 05:37 PM

Be sure the EDF is adjustable rearward (as well as forward) to achieve CG when accomodating huge (or higher cell count) batteries.

#15 AIR SALLY Apr 21, 2010 07:05 PM

got ya ....i think a 5000 4s or 3200 5s might be the limit;) we'll see .

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