Engine for Balsa USA 1/3 Pup

[Phillip Archer]

Do you guys think that a 70cc (4.2cu in.) Sachs-Dolmar gasser would be a
suitable powerplant for the 1/3 scale Sopwith Pup by Balsa USA?
I've thought about this kit before, but never had the engine to put in it.
Now I've been offered the Sachs at a reasonable price, my mind has turned
back to the Pup.
Anyone flying one? Any comments, tips, reviews etc?
TIA..
Phillip...

[Richard D.]

Hi Phillip,

Yep that motor will have more than enough power for the pup.

I'm using the Zenoah G-62 with a PSRU, Prop Speed Reduction Unit, that
reduces the prop speed from 8000 RPM to around 5500 RPM which gives me the
option of running a more scale looking propeller, at 8000 RPM I would have to
run a 22-10 prop where a scale size would be 36" prop, with this set up I'm
running a Menz 30-10 prop.

My pup has been modified right from the start with the two piece
stringers, supplied in the kit being, replaced with one piece spruce
stringers, spruce spars instead of the redwood supplied in the kit.

The wing butt rib attach dowels being replaced with aluminum tubing, in
both the wing and the center section and fuselage, that slides into each other
providing a more secure wing attachment, a friend had the stock attachment and
when he did a nose over the wings, both upper and lower, rotated forward and
hit the ground.

The redesign of the flying wire attachment mounts on both the fuselage and
the wings, I make 1/3 scale turnbuckles for the pup, and a more scale looking
landing gear spreader bar with functional bungee cord retained axles, I make
these assemblies also.

The kit requires a lot of building, it is almost a scaled up Guillows
stick and tissue type of kit so to make it a little easier to assemble we
used, my partner and I, both wing, fuselage and tail section fixtures so
everything would come out straight.

The pup flies like a BIG kite. So until you have some experience flying it I
would recommend not flying it on windy days, with a 15-20 knot head wind it
will hover!

I have built or repaired 6 Balsa USA pups.

If you need any more info on the pup feel free to contact me.

Hope this helps.
Richard D.

Airline Mechanics Credo:

We the willing
Led by the unknowing
Have been doing the impossible
For so long
With so little
That we are now qualified
To do anything
With nothing at all...

[Roger Forgues]

With a prop drive, you can use a much smaller engine for slow flying
airplanes, if you check on my web site, and click on "Henrik Rossell" you
will find a half scale J-3 Cub with a 52cc engine but on a Tonini reduction
drive.
Roger

--
Multiplex Dealer
Fiber Optic Servo extensions( Pure Light)
http://www.aerografixs.com
"Phillip Archer" <phillip...@newcastle.edu.au> wrote in message
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