Pete S-RCU

I'm almost ready to maiden the 30% BUAS Stearman.
Has a Evo 7260 radial engine, 32x18 prop.
Be interested in advice from anyone who has flown one before.
I imagine I have to keep a little power on, on approaches because of the hi drag.
Are the stalls gentle?
Anything I should be aware of?

wildbills21

Pete,
Many flights with the 1/3 BUSA Stearman with the Moki 215 and similar prop. A little right rudder on take off. As far as stalls, power on stall drops the left wing a tad, power off stalls the nose pretty much drops. As far as landing you will be surprised how far the plane will fly with that size and pitch prop at idle As far as my stearman I can chop the power on the final turn on a calm day. If its windy you may need a little power on final. The plane is a very pilot friendly flyer. No bad habits at all unless self induced if you know what I mean, Have a safe and successful flight.

Wild Bill

Pete S-RCU

Thanks for the advice Wild Bill, I'm waiting for the weather to warm up a little before I give it a try.
I have a 34x12 prop I was using for breakin, think that will work as a flying prop too?
These big props are different from the 20" or less props I'm used too.

jetmech05

I have not flown your airplane but I have flown a couple of bipes.
Stall it at altitude to get a feel for what you've got.
If you have used throttle management you'll be ok. I kept a bit of power on coming out of the final turn. Set the glide path and brought her home.

Greg Wright

My Feedback: (6)

Any news on how the test flight went??

Pete S-RCU

No test flight yet, not quite ready.
Got the CG located where it should be.
Used the three scales and a ruler method, seems OK.

Next question, how to keep the burnt oil from leaking out the fittings by the exhaust ring?
Makes a big mess, but it's probably a scale mess?
Maybe Permatex on the fittings?

jetmech05

Clean the openings in the exhaust rings and on the header use red RTV just enough to coat the surface bolt the header on rub the excess on the seam let dry

foodstick

It must fly pretty good as I just watched a video of one landing after BOTH tires had fallen off ! it slowed down enough they slid it to a stop with a minor flip at the end.

The video is 90 degrees off, and I am not sure if its a 1/4 or 1/3rd Stearman.. but check it out !

https://www.youtube.com/watch?v=zLoMajUz2uo

Pete S-RCU

How did the video get turned 90 degrees?
For the exhaust leak I was wondering if Teflon tape wrapped around the joint would work?
The temp would be the only problem.
I will have to do some research.
Don't want to have to remove the engine again if I can help it.

Pete S-RCU

Went to NAPA and got some exhaust sealer, good for 1600 degrees.
RTV is only good for 600 degrees, exhaust gas is between 1200 and 1400 degrees.
Will see how it works.

Pete S-RCU

Maiden went great, a real nice flier.
Got cyl head temp on one cylinder, have contrived a tach for it too.
Spectrum makes a sensor you mount on the backplate of a single cyl engine, it senses the crank pin when it comes around and sends a pulse to the TM1000 rpm port.
Tried to find a spot on the backplate of the Evo7260, but couldn't locate any signal.
Crank pins must be too far into the engine.
Drilled a small hole on the hub of the prop and glued a small washer into it.
Made a plywood bracket to mount the sensor and glued it with Dap Goo to the front of the engine.
Works like a champ, now have a good rpm readout on my transmitter.
Not supposed to exceed 5k rpm on this engine, don't know how much it will unload in the air.
Will find out soon.

jetmech05

Pete aluminum melts at 1200F I think you're EGT of 1200 to 1400 is slightly off. I'd be very leary of gluing things near the front of the engine or drilling into a prop hub.
Glad the maiden went well

Pete S-RCU

Exhaust gas temp for gas engines is in the 12-1400 degree range.
Cyl head temp is about 400 degrees, and related parts are much cooler,
Have to consider, burn is only one of four steps, cool mixture comes in between every power stroke.
Then there's the cooling air over the cyl.
Ever seen a lean run that melts an aluminum piston?
I'm amazed at how cool this engine runs, cyl head temp by the intake valve is only 140 degrees.
Will move the sensor to the exhaust valve next to moniter that temp.
The front housing is so cool you can touch it after a flight.

Pete S-RCU

Here's a video of it.

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Way to go, jetpete!
Your video is now on YouTube.


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Pete S-RCU

20160518135323

That's better