RoJett or PA40??

Sound off . . . . . and thanks.

Thanks

Bob Hunt. It was a new set-up for him. New plane, new engine, new set-up. It doesn't all come together in a day. Still, he flew to the first alternate position.

I was running a RO-Jett 61 BSE, as were RO himself, naturally, Windy, and Kent. Mine ran fairly well, and very reliably in significantly varying conditions, although it may have been "on the edge" on the cold mornings with my QM-40 type settings and 15% nitro.

For reference purposes, this was my setup for the RO-Jett 61 BSE:

Stock BSE engine with QM-40 style crank timing
High-compression (.085 projection) head button with 1 .002 shim
Eather 12.5-3.9 "Green" flat-back 3-blade
Stock venturi bored to #6 with SIG eyelet "spigot" with about .030 projection into stream
pipe pressure into uniflow vent
dual-taper 7.6 oz uniflow tank
nylon stocking filter/diffuser
Smith-Werwage diamondback 61 pipe, 17 7/16" to first baffle
Thunderbolt 4-cycle plug
SIG 15% fuel, unaltered, roughly 7.1 oz of fuel for an FAI pattern
10100-10200 rpm ground launch RPM

I think this is the first setup that I had that was close enough to publish in public. It DOES NOT run much like a PA61 in most regards - it's a different breed of cat entirely. Just as a subjective comparison, a PA61 runs like a PA40 on "Lyle Alzado" levels of steroids. A RO-Jett 61 runs like a 46VF on "Lyle Alzado" levels of steroids, except that it likes to 4-stroke.

Despite the fact that I ran my RO-Jett instead of the PA, and then grenaded my RO-Jett in front of a crowd at the NATs, both Randy and Richard (and Dubb Jett) were perfectly gracious about it. I'm sure it was a pretty awkward situation for all of us (certainly was for me!), and they both have my thanks.

Hunt's motor was up and down over the week as they struggled to refine the engine, prop, and airplane all at once. Given that no one has really had time to do the "full treatment" of development on the 40, that isn't at all suprising, and I thought they made a lot of progress in a week. A lot of people pitched in to help, and I think it left in a lot better configuration than it arrived, that's for sure. The only thing I know for sure was that he was running a #8 spigot venturi, since it was one I gave him (as it was way smaller than I needed for the 61). He obviously did pretty well with it by the end.

Engine breakdown:

Werwage - PA61/Smith-Werwage pipe
Walker - Saito 72
Fancher - Modified PA61/Eather pipe
Hunt - RO-Jett 40 BSE/Future Force pipe
Rich - PA61/Smith-Werewage pipe
Fitzgerald - PA61/Eather pipe
Buck - RO-Jett 61 BSE/Smith-Werwage pipe
Oliver - RO-Jett 61 BSE/Jett Pipe
Smith - PA51/Smith-Werwage pipe
Urtnowski - RO-Jett 61 (cast)/Windy pipe
McMillan - PA61/Smith-Werwage pipe
Geiseke - PA61/Smith-Werwage pipe
Contrata - PA40/Smith Werwage pipe
McDonald - PA61/Smith-Werwage pipe
Hemstrought - PA51/Smith-Werwage pipe
Neumann - PA61/Smith-Werwage pipe
Powell - PA61/Smith-Werwage pipe
Scott - PA61/Smith-Werwage pipe
Tysor - RO-Jett 61 BSE/Windy pipe
Granderson - Magnum 36 XLA II/Smith-Werwage pipe
Brickhaus - PA61/Smith-Werwage pipe
Sunderland - Stalker 61/muffler

I think this is a complete and accurate list - thanks to everyone for the inputs.

Kent won Nats Advanced with a Barstock ROJett 65, he was flying a Barstock ROJett 61 for the Team Trials.

Stan Powell was probably using a PA61 that is what he had earlier this year. (I think pa51 maybe.)

I know that Dave H. was experimenting with a LA46/Pipe but do not know if that is the plane he flew.

Hope that fills some holes...
a.l.

Yes, Paul Walker was. There are not that many in use by the top competitors in the US. It is another learning curve, and it also works differently than what most are used to. There will be some who try them, but it is another learning curve. They work. But the question remains, "Do they work better?" For most people is is mrely another choice.

I do not think that it is a question if "4C is falling out of favor". There has not been that many four-stroke motors used by the top flyers at this level of competition here in the U.S. Four-stroke motors are not uncommon among the Europeans. The French have been quite successful with them.

They turn a Gieseke designed Bill Lee three blade 12 1/2 X 4 cut down to 11 X 4 at 10,200 RPM. They pull 50 plus ounces on 67.5 feet of line effortlessly on a strong four cycle. They are flip-and-fly user friendly. I don't see any reason to look any farther as I plan to stay with the .40 size ship.

That's my experience. Dee Rice

This is the third season I have been running a PA 40, and I will continue to fly with my present set-up for another year or two. Since I first removed the motor from the box, it has been a jewel. As for ease in starting, I reliably get “Spinner Flick Starts”, the first time, every time (even during the break-in process).

* Spinner Flick Start – The tip of the spinner is pinched with two fingers and it is bounced back off compression in a clockwise motion resembling snapping your fingers. The motor starts immediately, never having touched the propeller.

With just 55 flights on the motor and airplane, it placed fourth at the 2002 Nationals. The only learning curve I had was how different it sounded than that of my .61’s when setting the needle. I am running an Aero Pipe set at 16.75”, Bolly 2 blade 11.5x3.8”, SIG Champion fuel of 7.5% Nitro 20% Castor/Klotz + Aero 1, a ground launch RPM of 11,200, and lap times of 5.4 seconds. by the way, everything I have is box stock, & off the plans.

The running characteristics are what we think of when we talk about the “perfect stunt run”. In maneuvers it cycles 4-2-4, very quickly responding to the exact needs of the situation. The motor smoothly and predictably cycles on and off, and holds back very well on the bottoms of the Hourglass and Vertical Eight. On the hourglass, it breaks into a deep four stroke about 10’ before the bottom right corner, it is a beautiful thing when you feel it hold back. It does the same on the downsides of the Vertical Eight and Wingover.

The available power in this motor is remarkable, and it is smart about when it needs to deliver. It is hard to explain, but the PA 40 makes my model fun to fly, as if it is with me all the way, helping me to fly the airplane.