NVA & "Attitude/load Sensing"

Yesterday I made some more progress on the .40FP/Macs Muffler/tornado 3 bl 10-4 setup described by Scott Riese.

Everything is now the same as his original description with only one exception: I am running a venturi with the Stock OS (R/C) spigot into the center of the venturi.

His original described an Enya NVA/.279dia venturi.

My choke area is a few percent larger (exactly in the middle range of Area/Displ (ref. Neumann) so I started with a Bruline filter on it.

Yesterday, it ran well but was a bit weak (density Altitude was 2400ft 82deg and 71 deg DP) So I removed the filter. It got stronger and was flying rock solid 5.0 sec laps on 60' eye to eye on the twister. Nils observations were about 5.3 sec on 62-63' so I think I'm very close to the right set-up.

It was very consistent. beginning to end of flight same speed.
(it would not do this with castor/synth blend by the way--got ok with Sig 10%/ 20%all castor lube)

My question is this: Should I expect to see any better load-sensing ability from a "regular" NVA (Enya, OS) instead of the Spigot?? When I point the nose up, it loads down and doesnt "perk up" Never really winds up pointing down but offers no Punch going up. Or is this more likely related to my RPM set point? (I was having some trouble with my tach on the three blade, so was setting based on lap speed.

Stock head shims.

It unloads a fair amount a picks up RPM after take off.

Any Ideas??

Thanks

Somewhat similarly to engines that break "too hard" to be used as part of a 4-2-4 system, it may be easier for the all-two-cycle motor to want to keep on accellerating in consecutive maneuvers, so the trend now is to use low enough pitched props that the speed-up is negated.

Before the 4-2-4 runs caught on, most sport and stunt flying was performed at faster speeds than eventually became the norm. My Green Head Torp 29's and 35's, on sport fuels, with stunt props, were flying slightly above 60 mph (4.2 sec. laps). Some fliers still flew even faster than that - speeds in the 70-85 mph range for stunt had been fairly common with the pre-1950 competitors, and some of them were still on the scene when I started going to contests (3.6 sec. laps, and faster).

Today, most aerobatics flying is flown at about 51-55 mph (4.7 to 5.0 sec laps), although there is a lot of talk about 5.0-5.3 seconds, and I'm sure some fliers are sticking to those slightly slower speeds, I sat with George one evening watching tapes from a Brodak fly-in, a Nats or a VSC that neither George or I had attended, and he was regularly running a stop watch on the flights, to support his contention that most were "too fast" (in his opinion, even 5.5 second laps were fast - and that's only 47 mph).

The earliest FP's came out about 1986 or 1987, I think. I had one each of the 35 and 40. I wouldn't pay the price for any of the high-dollar carbon fiber props that were becoming popular, and if Grish was making a tri- blade 10-4 then, I was unaware of it. I tried two-blade 11-4's of several affordable types, but found no 11-3's in my budget range around at that time.

My experience was a runaway situation on most flights (I did find that the 35 was a bit more docile with a couple of the 11-4's I tried on it). Had I been able to try some 11-3's, I think I would've liked that first FP 40 better. You might look around and see what is available today in the line of 11-3 two-blade props!

Kiwi

This weekend, at the C.O.L.D. Stunt contest that Nils CD'd, I was witness to Scott Riese himself flying his Brodak Profile Oriental with FP .40, Mac's Muffler, and Tornado Magnum 10-4 3 blade. He says the key to the thing working is SIG 10-25 fuel. His lap time was right around 5.0, altitude 3,300 and temp was in the high 70's or low 80's with low humidity, guessed at about 15/20%. Last year, I saw Nils fly his own Brodak Profile Oriental with the same engine/pipe/ prop/fuel combo at the same field and about the same conditions. Both showed plenty of power for a significantly larger model than yours. If you need more snort, try 15% nitro, but if it doesn't rev up a little when you raise the nose, you're too lean. Steve

I'm think I'm pretty close on this setup as I said. Its going to cool down a bit and dry out some this weekend, so I'll give it another go. THe 85% humidity and mid to high 80 temps are a killer.

I could ad a few oz of oil to the 20% stuff here. I know in Scotts early info he indicated 20% MINIMUM castor. I suspect the 15% or maybe even 12 Nitro would help a little also. It should allow me to run a little richer and make the same launch RPMs. (If I've absorbed the Nitro Use information from this Forum correctly)

I'll update after next flights.

Thanks