RE: PICA Spitfire 1/5 Please Help
If you can get the wight down to around 20 lbs the ST-3000 will fly the spit with authority.
The key to achieving the low weight is to keep everything aft of the wing as light as possible.
I replaced a most formers with balsa and carefully sanded the skin down to slightly more than half its original thickness before gluing it on the rear fuselage. The stab/elevators and the fin should also be put on a diet. Using closed loop wire linkage for elevators and rudder will also save a couple of ounces. Remember that every ounce in the tail equals approximately 5 oz. of lead in the nose!
IMHO an 18*8 is to little prop for an ST-3000. These engines need to be loaded down. An 18*10 prop will produce better results.
With the 18*8 there is to much RPM and not enough airspeed. Ideally the ST should be propped to approx. 7500 RPM on ground. It will unload a couple of hundred RPM. Remember, peak horsepower is deivered at only 8000 RPM.
Good luck with your Spit. It's a beaut!
/Red B.