HI Brad,
Glad I can "crack you up"! Everyone needs a good laugh every now and then.
Also, everyone has their own "opinion", which I stated as being so. So, in your opinion, we don't need any excess "usuable power" in our planes. Hmmmm.... seems to go against every one that I talk with about that. Hunt, Werwage, Gieseke, Fitz, Windy, Al Rabe, et.al., seem to have said that some extra power is quite good. Al even made a point for me to use a PA 61 instead of a PA 51 in my Classic Mustang I build. I'm sure the 51 would have flown it just fine, so why was he insistant that I use the 61? More power.
The ST 60 being a match for a PA 75, in stunt use? No way. Plain and simple. The PA 75 has more grunt whether on a pipe or on a muffler. And it's as easy to run, maybe even easier if you do what Randy says.
This event is great because there are so many different preferences in how we do things. The way you do it, I do it, or anyone else may well work, but it all comes down to what we prefer.
I have not seen the problems of installing a larger stunt engine in an airplane except for balance issues. Taming the power is simply a prop choice, usually. My first experience in seeing this was Tom Dixon's T-Bird II with a ST G51. Tom can fly pretty good, so that might not have been the best example, but the plane didn't care where the wind was blowing at all at the Huntersville site where the air can be really bad.
BTW: my reference to what "Many" will use is in no way a reference to what the World Champion class fliers may or may not do. Just the rank and file stunt flier who wants to fly the PM and assorted size planes and use the giant size engines.
Ain't this fun!
Bill <><
I guess I misunderstood, because I certainly did not mean to say "you" crack me up. I must have misread what you were saying, so I did not mean for my comments to read as a shot to you...or anyone else who wants to fly a big plane. I say have at yeeee!!!
Instead what I meant was that there is definitely a wave of going to larger planes (which I see as the height of irony---this cracks me up), solely because there are larger engines available all to gain what? Power to weight ratio (certainly not noise reduction)? A greater power to weight ratio could be found putting a mild 60 like a Stalker in a Nobler (as a fellow in Australia did in the Aussie Nats), but what is the gain when an L&J Fox 35 will pull it through a pattern with authority?
I flew the PA 75 for pretty hard for 6-7 months, so I guess I can state an opinion about how it compares to a ST 60. The PA 75 has way more power, no doubt. However, once tuned to a level of "usable" power, the results are the same as with any other engine. This idea that you can have the huge excess of power in reserve are two things: a myth, and a recipe for disaster if something goes wrong (like missing the needle). Heck even David Fitzgerald was running 20% nitro in his PA 75 at the last WC's. Why? IMHO, it was because the engine had been tuned to a stunt run, and it had no more reserve WHERE IT WAS TUNED. The extra nitro was needed to gain a little boost from this tune point. This result would have rung true if he had been running a .40.
There are problems associated with detuning engines. Our 2 strokes like to be run at a certain load. trying to run significantly less can lead to all kinds of issues (running cold, run less than steady, changing from run to run, being touchy) in fact, the opposite of what some people think they are gaining going to bigger engine. In fact, 2 strokes like to be closer to peak than, idle, and you can make the argument that smaller engines running harder are more consistent because of this fact. So, if you think that you can take an engine that can easily run a 16"-17" prop and stick a 12" inch prop on it and it will run better (maybe your airplane like a 12" prop) it won't. 4 strokes really like to be loaded, and unloading them can lead to all kinds of racy screaming super hot runs.
Randy can jump in here, but he does not run a bigger engine than he needs. He has expressed these same ideas that having "enough" engine, that gives you good run with the prop you like is all you need. Randy himself runs the PA 51.
I flew with Bob G. off and on for 20 years. I thought he flew best on the G34 Supertigre and the PA 51. Going to larger engines never led to an "improved" pattern. As light and small as Bob's planes were, he could have run a modern .40 and never changed a thing, except it would not have sounded as cool.
BTW, I think a G51 and a TB II is a good choice. I know lots of folks who put ST 46's in TB II's. I do not see a ST 51 as a big jump from a St 46.
The best PM I ever saw was Bob Baron's. It had a ST 60.