UK Nationals Gold Trophy winners

1974   Pete Tindall   Chipmonk   Fox 40   





So had to ' resist ' the temptation to aquire one . Some snivling git was whining the 4-2 made them seize on the 2 as they got no oil .
This goes with T120 bonnevilles break there cam chains , Id think .

havnt run one myself , but youd save on NOSEWEIGHT .   Likely useing glue , ply doublers and 1/2 square bearers necesary
with old iron piston things - a engine bed - as the vibes tend to unglue stuff . Tindall used a 11 x 5 Punctillo ( prop ) offset even.
The bladesnot centered on line through crank . were popular back then in europe . A.M.A. has the plan . Published in Aeromuddler
and the U S . Good in depth construction & light weight finishing artical in the magazine . Seems a compatant aeroplane .

     Hi:

     Thanks for the replies!

     I wanted to use an 11X5" prop on the Magician but there was no Clarence betwen the prop and and the grass.  This, I went to a 10X6" which just got airborne by mowing some grass!  I was thinking of a 9X8  three bladed prop for a bit more of grass clearence.

    Yes, one most likely have to add nose weight with this engine.  It weighs 8 oz.  It did not rev up like the 1972 Fox .36 plain bearing but what a strong 4 cycle and a great 2 cycle break.  No, it is not modern, but so am I! Lol

     Thus far, I really like this engine for stunt use.  One big problem! There are NO spare parts from Fox for this engine.  Perhaps there are people out there who have some squirrled away.

                                                                                                                 Stay well my friends,

                                                                                                                  Frank

     

The Olde TORNADO 9 x 6 three blade might be the trick . the 10 x 4s & 10 x 6s are good . Soaking in a plastic bag , damp with armouralll
softens even brittle old yellow Tornados , that snap in your fingers otherwise .

Sounds like you need bigger wheels or longer legs though .

      Hi:

      I just remembered that I am using a pair of 2.5" wooden wheels on the Super Clown that I am now flying! It needs larger wheels to permit takeoffs and landings without flipping over! Lol

                                                                                       Stay well,

                                                                                       Frank

I campaigned a later series of the big case 40 for several years  in the early 80's... That was the ringed 2BB, matte finish case model with the straight, not bulged bypass.

It took a while to dial in, mainly because it needed a very different "tank height" setup to run the same both ways. I did reduce compression by cutting the head button to a straight cone from the cylinder wall depth to the plug depth. Reason: in the stock the flat squish and bubble combustion chamber only the bubble showed a charred hot spot, while the rest of the chamber volume was not heated much at all. Ran a bit harsh as stock; much smoother and more economical as mod'd. No burn zone in the mod head after hundreds of flights, just an even light tan.

The engine was so smooth - with good power - in a juicy 2-cycle that I didn't push for a 4-2 run. I had two near identical originals - the Atavists, if anyone recalls them - same area, around 675, same weight - a bit over 50 oz, same perfprmance (VERY good). The other had an OS 40 FSR CL. Another good engine. No power problem with either engine - plenty, consistent and dependable.

The second Atavist had a more tapered wing, with same % airfoil root to tip. It was more susceptible to roll deviations in choppy wind, but otherwise they were well matched. I since use a thicker % airfoil out towards the tip...

It took a while, but once the tank height was right, that Fox 40 BB Sch was excellent. The head mod could possibly be done with an extra gasket or two, but the cone simulated a demolition 'shaped charge' form...

I ran one in the early 70's just after it came out.  I  really liked it,ran a Rev Uo 10 x 6 and a Power Prop 11 x 6.  Used K & B 100 fuel.