OK, The OS .45 FSR running in a stunt plane.  Best set up?

Thanks
Big Bear

Hi, Bill, seem to recall the guys using about a 12/4 prop with that engine...with limited success.

  Hey Bill,  glad to see you're back on your feet. I tried running the .45s a bit & they were ok  I used an 11-6  about 8800 RPM  seems like it had a burp in transitions in the 8s   I liked the weight compared to my Magnum .53s  .
  Hope this helps, John

Thanks, Guys!

Still a while before I can actually fly, the chemo is messing with me right now, but I am looking forward to getting back out!  I am getting some building done (finally) but the "stuff" makes my hands shake like crazy................

Bill

Thanks, Mike.  I was pretty sure these are "high rpm/low pitch" engines, but not sure if they run in a wet 2 or actually have a break (2-2 OR 4-2).  Was considering if I needed to get it breathed on or not.  I feel pretty sure Randy can spec it if necessary.

I have a couple of HP .40s that Aaron and I are planning on using and am "guessing" the .45FSR is a bit stronger.  The  HPs (one is a Gold Cup, NIB) have had the sleeves dropped, etc., and will run a lo pitch prop and turn around 10,000 rpm.

I am planning to build a couple of Don Hutchinson's Warbirds (planning while I can't do much building or flying! LOL!!) and while the LA .46 is a great match, I have these engines, too, and they need to be used while I still can.  

THE .45 FSR is being considered for a light scratch built Sig Magnum.

Bill

I think it would respond well to blocking the boost port -something that was not discovered until folks gave up on the FSR's (40 45 & 50)

   The way we were trying to run it at the time, probably right. It doesn't care for chugging around at 8500-9000 RPM. The partial solution was 4" of pitch, so you *don't* chug around at 9000 RPM in flight. The full solution was 4" of pitch and a tuned pipe. But if you are going to do that, you want an RE version, i.e the VFs.

   A different partial solution was to use an ST60 instead. It has a lot more power at the revs required for 6" of pitch at low revs. The 45FSR passes the ST, in terms of power and torque, at around 11,500 RPM. Which is perfect for 4" of pitch. Blocking the boost port reshapes the torque curve so that it dies off more quickly with RPM and makes it more stable at low revs (curing the runaway you get with large 6" pitch props at low revs) but you are WAY behind the ST60 at those low revs anyway. Which is why everybody dropped the 40/45FSR like a hot potato as soon as they discovered the ST60. It was all laid out clearly in Scott Bair's report.

   The other problem was the ring tended to wear out, which Bob Hunt solved by changing to an HP40, Paul solved by using an FP cylinder/piston, and OS solved by using an ABC cylinder/piston (VF again).

   I think the 46SF is A LOT better than the 45FSR in pretty much all the variations, and I think it fits the same mounts. But, mercifully for us all, the "Schneurle of the Month"/"Schneurle Wars" motors from the late 70' early-early 80's was brief, and everybody moved on to "ST60 VS Tuned  Pipe wars" as soon as possible.

    Bill's application is unique, but I would hate to see people go back down this road again due to nostalgia for the good old days of 1981. Because, for the most part, they sucked compared to now!

    Brett

Thanks for the explanation.  With the disappearance of available PA engines and rising costs of cancer treatments I am looking at engines I have now and trying to get use out of them.  The Magnum is slated for a refinish (tried low cost iron on it and it didn't work.  Maybe 25 flights on the plane, or less.  A practice, bad weather plane for our use.  If I get a decent wet 2 cycle run anywhere similar to a modern OS engine, it will serve its purpose

    I would look at Paul Walker's version of the 45FSR setup. It appears to have been the most successful.

    Brett