H9's Sundowner

[mfuess]

I suspected and confirmed that my stock muffler creates too much backpressure at higher RPM's. I looked all over the internet attempting to find a header & pipe. I found a pipe, but no header. So, I made one. I won't see the pipe for several days, but I have no doubt it will un-leash the topend. Maybe, just maybe this will get my Sundowner up to my expectations...

[dptp9lf]

I thought about putting my ZDZ Super 80 in the Sundowner... maybe that's what it will take?

[Flatlandman]

That would need more work than the da 50 for sure lol but I bet it will haul ass.

[dptp9lf]

Probably be a trade-off in flight characteristics though...

[mfuess]

I managed to hit 123.9 MPH today just by changing the exhaust. I knew that stock muffler was holding it back!

[mfuess]

My 25mm header allowed the BME to un-load the air taching 10,890 RPM, thus pushing the Sundowner up to 123.9 MPH on a 12 pitch prop. I have a lot more speed (and power) available if I bump up the pitch to 14, 15, and possibly 16.

However, I can't really run an open 25mm pipe as the noise is totally un-bearable, 119db @ 1 meter. So, to correct this without giving up too much power I made another header to stand away from the fuselage a bit more, then I modified an MTW 75cc canister to allow the 50cc to un-load as though it was an open pipe. (HOPEFULLY)

[Flatlandman]

The sound I got from the straight header was also very loud but is no prob in the air. OUr feild doesnt have any noise restrictions and being near the landfill has no houses closer than 3 miles away other than a barn or 2.

[mfuess]

We have a residential area about 1/3 mile away, so we try to watch the noise. I like the canister! It lowered the noise 23db, plus I got an additional 1250 RPM out of it. I spun an APC 16x11 at 11,830 RPM to see how noisey it would be... the prop got up to 110db.



I should see about 130 to 135 now. My last recorded speed was 123.9 on the 25mm pipe and now I have an extra 1250 RPM to play with, plus whatever it unloads at in the air.

[rcplane]

Wouldn't you get more speed with say a 16x14 prop at less rpm's?

Mike

[mfuess]

	Quote: Originally Posted by rcplane
	Wouldn't you get more speed with say a 16x14 prop at less rpm's? Mike

That's correct Mike. I ordered an assortment of props yesterday ranging from 16x12 thru 16x16. Plus one 16.5x14. One of these props should be the magic number...

I ran the 16x11 mainly to hear how much prop noise to expect.

[mfuess]

	Quote: Originally Posted by dptp9lf
	I thought about putting my ZDZ Super 80 in the Sundowner... maybe that's what it will take?

Actually, you would be very disappointed.

[dptp9lf]

Not that I was serious about the ZDZ 80 install... but how would I be disappointed other than the fact that it would be too heavy, I would need a taller landing gear, it would shake it apart, and it would be a sled in the turns?
Cheers,
Lyle