Group,

Flew my 13th flight and 13th hour in my S1S today. Absolutely loving it!

Couple of questions for the Pitts drivers out there.

I am swinging a metal sensenich 76 x 56 with 180 hp O-360 on my S1S that weighs 740 empty. It goes up like a rocket but it is so easy to overspeed the engine that it is not funny. Anything over an 80 mph climb takes a serious throttle reduction not to exceed 2700 rpm. It only takes 1/3 throttle at cruise, anything more than that and it overrevs. At 2700 rpm indicated in level flight it will not loop. Its just too slow. I have to dive for airspeed. Is that normal? I am thinking of reproping to a -58 or -60. Any thoughts?

Gus

PS - Landed on a grass strip for the first time today. Wow, talk about taming the tail. It really reduced the foot work. I was concerned about the lack of visual cues with no concrete edge but that proved not to be a problem.

• RE: Racking up the hours and loving every minute/Prop question,TomParsons, 17:39z, 07-07-03
  • RE: Racking up the hours and loving every minute/Prop question,grant4ever, 00:57z, 07-08-03
• RE: Racking up the hours and loving every minute/Prop question,TomParsons, 12:29z, 07-08-03
  • RE: Racking up the hours and loving every minute/Prop question,grant4ever, 20:16z, 07-08-03

Gus-
Glad to hear you're having fun!

My airplane is similar in some ways to yours (fairly light S-1S with a ~190 HP AEIO-360 in my case). I don't happen to know my prop's pitch off the top of my head (I'll check when I get home later), but I do know it's set a bit coarser than an optimum cruise pitch would be. So I don't have as much of a problem as it sounds like you're having on climbout. I tend to climb at more like 110-120 mph, at full throttle, and I am not exceeding redline. So it sure sounds like you would benefit from a coarser prop pitch.

What airspeed are you cruising at? In my case, I think I'll cruise at about 145 mph indicated, at 2700 rpm (2500 MSL).

As far as acro is concerned, I asked lots of questions about rpm management during acro before trying it in my S, and have decided to set my personal "acro redline" at around 3000 - 3100 rpm. I'm told by several experienced pilots that you do no particular extra damage to the engine by running that high, except that the tach hours wind away faster! Also, you don't get much extra thrust once you go above 3000 anyway- just extra noise. But for my prop, that rpm level lets me pretty much set the throttle to the stop and forget about it during a sequence. At full throttle, I end up having to just barely descend, giving up just 100-200 feet, to get to looping speed of 160 mph and 3000 rpm.

Again, I'll post again after I get home and look up my prop specs. Hope this helps!

Tom P.

I too don't mind spinning mine up to 3100 rpm when doing acro.

I usually cruise at or near 2700 rpm with only 1/4 to 1/3 throttle. It spins up to 3100 fairly quickly if I point it downhill.

I don't tend to make to many throttle adjustments while flying aerobatics. I pretty much set 2700 and forget it. I try to keep it under 3100 by keeping track of the airspeed. Is this the way to do it?

I seem to be diving quite a bit more than you to get it up to speed. I will have to pay more attention next time I'm out.

I have so little experience that I don't know what the "norm" is. That's why I am asking the goofy questions.

Gus

Gus-
I checked my airplane logbook, and verified that my prop is a metal Sensenich 76 x 60. With that prop, I run acro at full throttle.

I am trying to learn to fly the figures in such a way that I will not have to pull back the throttle at all (except for spins, of course!). I'm told that it will be hard to get good figures, especially round loops and straight 45 downlines, if I pull the throttle back.

Like you said, controlling airspeed controls rpm. For example, in a hammerhead I can (try to) use the timing and aggressiveness of the pull after the downline to keep the airspeed where I need it for the next figure.

Tom P.

A -60 huh?! I guess with 190 hp on tap it still pulls nicely and gives you a higher cruise speed. Mine, with 180 hp would probably work better with the -58. I am just guessing though.

I sure with someone with a zillion hours of Pitts time and knowledge would jump in here and give their two cents.

Gus