Primary Force ARF in Action at Sig ContestI originally powered ours with an FP 20 w/BBTU mod. First flights in a moderate wind were disappointing. Model felt light on the lines to the extent no maneuvering was attempted. I sure couldn't see one but the wing must have had a slight warp which caused the outboard wing to fly high when upright. I didn't feel confident enough to pull it inverted to check. Lap times on 60' lines were 5.3 seconds.
Only modification to the stock configuration was substituting MonoKote hinges in place of the CA hinges.
After getting some suggestions on SSW I opted to re-engine it by dropping in a Brodak 40. No cutting was necessary but I did have to drill new holes. The B40 is a pretty lightweight engine. APC 10-4 prop and stock muffler and an all-up flying weight of 39.5 oz.
I used a heat gun to unwarp the wing then with time running out before heading down to the Sig meet I had my 14 year old fly it. The B40 produces much more useable power. It seemed fast watching it from the outside but the kid said he really liked it now - especially how it turned. He did wingovers, inside and outside loops and some inside squares. I had added another ˝oz of tip weight in the built in box.
I entered him in the Sig P40 event as a junior as well as PAMPA Beginner. I didn't complete the modifications on my Fancherized Twister so was going to fly either a U-Key 40 (FP 25), a TF Flite Streak ARF (FP 20) or TF Tutor II (LA 46) depending on the wind conditions at Sig.
On the drive down to Sig my son was asking me the sequence for the beginner pattern. He also said he wasn't sure he wanted to compete in P40 but I urged him to go ahead since CD Mike Gretz said they usually have separate prizes for the juniors.
He also replumbed the stock Kavan tank to a uniflow setup. We did put the extra vent tubing through the fuselage.
First flight in P40 at Sig he successfully completes the entire beginner pattern - the first time he ever attempted the pattern in sequence and scores a 241.5! Positive comments from the other fliers that his corners look really crisp but the speed is pretty fast (he says he's comfortable with the speed). He passes on his 2nd flight and ends up as the top junior in P40.
His first flight in Beginner PA he got a little confused and started the wingover without completing sufficient laps after takeoff & level flight. Additionally he does the wingover going
into the wind! Still pulls down a 207 without pattern points. Bob Arata, who is judging Beginner, advises him to fly 5 laps after takeoff. Next flight he nails a 259 to best all the open fliers in Beginner (including his old man). He scored a 35 point landing. Even I could get that score landing this ARF - it is that smooth!
There were at least 7 or 8 other PForces in action at Sig. Five were ARFs and 3 kit/scratch built. One of the ARFs was Gretz's electric powered version.
Most of the PForces utilized the LA 25 and at least one a Fox 35. It seemed to fly just fine with either. A few of the other PForce fliers were commenting that the PF was a very "honest" airplane. Certainly it is capable enough for a young flier to go out with zero practice and become an contender. With 27 entries at Sig, the P40 event is an incredibly popular event. Having a competitive airplane which saves you the 10 pt no flap bonus is a big, big advantage.
Mr. Pratt has come up with a winner - it certainly made my son a winner at Sig!
Mike Gretz's electric Primary Force ARF seen at the Sig meet: