ORIGINAL: Razor-RCU
Is the "piped-48" a K&B Screamin' 48? I love those...
If I tell you, you gota promise not to laugh?
Ok, (whispering) it's an mds. Shush, don't tell anyone.
ORIGINAL: Downunder
11,000 is very close to the revs usually turned with piped engines in CL stunt. An OS 40VF with a pipe at these revs (set at about 18" from the plug to the first baffle) is considered by the experts as having roughly the power of a muffled 60. In this application the pipe is boosting torque at around the peak of the torque curve which means you can turn a bigger prop. This is what was done with the old OS Hannos to make them turn a 12x12 prop (at even lower revs, something like 9,000). The other thing the pipe then does is if the engine tries to speed up when prop load decreases in a dive then it goes off the pipe and holds the revs more constant so it's a governing device as well.
This is what I've been looking for. I knew the pipe would have to be long, but 18inches? [X(] As to the governing factor, this is a very clean airframe without the drag needed to fly constant speed style pattern so thats gonna help plenty.
I know this plane flies much better on a 60, but I've already drilled the firewall for a 40 mount, and a pattern plane without a pipe is like pancakes without syrup.
ORIGINAL: w8ye
I've been waiting for you to say that. I read this in a magazine some 15 years ago but have never heard it repeated since.
I've thrown this theory up on here several times and no one ever responded good bad or ugly.
Thanks,
Jim
I knew something like this existed, the OS 140 that was/is used for pattern has a pipe about two foot long but runs at low revs, just didn't wanna open my gob in case I put my foot in it.
ORIGINAL: w8ye
Running at 11,000 you will not get enough from a pipe to make it worth the expense.
Last quote, I promise
I've already got a pipe to use so I'm just trying to use what I got.
Thanks again guys, this is a lot better than I could have hoped for. [8D]