bones

Ok since i started this little adventure of gyroing, i have been, as im sure every one else has been, looking to get the most out of my motor, hence getting the most out of the gyro..
For about the last 12-18 months i have been running the pitch on my prop so as to not let the 912 get much above 5400 rpm, as this is where the torque is, and figureing that if the motor is spining a little slower, it would last longer,,,, how wrong i must have been, after talking to a guy that we all know(at least of) we descussed this at great lenghts the other night, and was told to put the pitch back to let the motor rev to red line, and was promissed better performance, AND this is the bit i was struggling with,,, even if i was reving the motor a bit more to do the same job, i would use less fuel.
So last night i messed around with the used to be 72" WD prop(now 69") and pitched it so as WOT straight and level was about 5700 rpm 100 under redline, just flew for 4 odd hours this morning and the results surprised me to say the least.
4Hrs of mustering ie WOT to idle, and cruise revs, used approx 50 lts(a tad over 12 lts per hr), that is 2 lts/per hr less than 2 days ago, before i adjusted the prop.
Also the oil and water temps were down, oil was 10* less and water about 5* less.
All this while the cruise revs were approx 150-200 rpm higher...65-70 kts at 4800-5000rpm
So what does this mean? well from my piont of view it means the motor was lugging, thus heating up the oil and water more to do the same job, also the motor was using more fuel for the same reason, like driving up hill in top gear instead of dropping it back to 4th.

Some thing else that was brought up in conversation YOU LISTENING RUSS people who fit inflight pitch adjutable props to their gyros with out understanding the motors needs will and can kill the engine, so just beware people .....

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Good gyroplanes are not cheap, cheap gyroplanes are not necessarily good

Sky Gazer

Bones.

That is indeed very interesting and when you think about it makes perfect sense - just a little daunting running so close top the redline.

How long hhave you been on this gyro adventure?

What gyro are you currently operating- Any Pictures ?

Peter

russ

Bones.........when me new gyro gets into the air with the whiz bang inflite adjustable prop, my understanding at the minute is.........

Pitch it full fine to pull the engine up at 5400, there abouts. [ soob EJ25 ]

Ok, into the air to cruise height, pull the revs back to 4000 there abouts, then dial up the pitch on the prop until the revs drop maybe another 100. The big difference will be the NOW ATTAINED faster airspeed for the same revs as if it were a fixed pitch prop...............sumin like that anyway

It's a $4000 purchase this prop, others are having great results with it too.........lets see

Anybody out there with the knowledge etc of inflite props..........bring it on, keen to learn

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I intend living forever...........so far so good.

bones

That sounds alright Russ, its just that i am sure i have heard that in the US people leaving WOT and screwing the prop up to cut the motor right back, this type of thing is what will do alot of damage from my understanding.....

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Good gyroplanes are not cheap, cheap gyroplanes are not necessarily good

Aussie_Paul

I am with you on this one Bones. IMHO you need to run a manifold pressure gauge to use an in flight adjustable prop.

I wrecked the bottom end of my first 582 by over proping it. It was lugging training all the time. The next 582 Bert Flood told me to run it at higher revs. This was an engine that Bert was given by Rotax to conduct tests on a couple of changes, and they wanted it driven hard, so I did not mind driving it hard, not my engine.

That engine went for I think 650 hours before Rotax wanted it back, and I believe it was in an excellent condition when they pulled it down in Austria.

Aussie Paul.

Brian

Thats good stuff bones, depends so much on the engine, rotax are obviously designed to perform all day every day at what we call max revs . The motor may well be capable of performing at another thousand of revs higher without damaging it. You only have to look at the old Caterpillar diesal which is more than happy to operate at full throttle all its life .Yeah, I know, ones a fast revving petrol and the other is a big diesel.

I agree with you PB, a variable speed prop needs the same instruments as a FW with a variable speed prop otherwise it is quite easy to over stress a motor. [Fuel flow and manifold pressure]


Russ, if the 2.5 is like the 2.2, 4000 revs will not hurt it one little bit, mine runs around 3800 most of the time.

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Brian Reid
Pooncarie
NSW

Fencing Wire

When I was a young bloke learning to be a motor mechanic (probably a fair while before you were born, Mark), we had to read about a lot of shit like "Volumetric Efficiency" and "Thermal Efficiency", among other things. I dunno why, because it didn't appear to apply to most of the heaps of shit that we worked on. Get your Googlemobile out and have a bit of a squizz and some things might make a bit of sense. 'Course, you might already know about all that, anyway.

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FW

I can't remember what I did for brains before shit became popular.

SamL

Can someone tell me what the optimum max RPM is for an EA-81 ?????

Regards Sam

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CrashTestDummy

Dont you mean optimum max depth!!!

A.....There aint an ocean deep enough.

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...Woz

niquenaque

Sam,

I can tell you they don't like anything over 6k, I'm sure mine went to about 6.2k with a loose drive belt on the prop.

Peak torque is around 5100, so there is not much point going past about 5500, lest you suffer broken push rods as I did.

Cheers,

Nick.