Matt Dralle
Site Admin
Joined: 08 Nov 2005
Posts: 26321
Location: Livermore CA USA
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 Posted: Tue Aug 18, 2009 5:13 pm Post subject: RV8-List Governor Control Throws... |
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Great pics, Stan. Thanks.
I noticed that your Allen head screws are drilled for safety wire. Mine aren't. I wonder if I'm still suppose to safety wire them...?
Matt
At 05:54 PM 8/18/2009 Tuesday, you wrote:
| Quote: | Photos follow.
Stan
The forward mounted prop governor requires some engineering to get correct movements. In the photo above, the aft position (shown) of the governor arm is the high rpm (flat pitch) setting. However, a control cable connected directly to it would cause the prop pitch to work opposite to normal operation. So the cable to the governor must come from below and the actuator arm must be rotated counterclockwise to align with the cable. That will force us to bring the control cable through the lower ramp of the baffles.
The cable bracket that Nelson made appears to be correct. I'll attach to the inboard side of the lever arm and I'm thinking about making a fairing to fit around the governor. I'll have to devise a slit rubber pass through for the cable to go through the intake cooling air ramps. I saw one on a RV-10 at SnF that should work
The prop control does not have enough authority to get full travel on the prop governor. The only way to get additional throw before hitting the throttle quadrant stops was to redrill the clevis attachment hole in the prop lever for the prop cable. Nelson marked it and we drilled a new hole that gives greater governor movement for the same amount of lever movement. It was as high as we could move the hole and it still wasn't enough, so on the phone to MT Propellors of Deland, FL to ask if they had encountered the problem before. I've heard of other builders having the same problem, but the guy I talked to at MT (Urgen) had not heard of it. He said we must have full authority to the high RPM end and we can accept not quite reaching the stop on the low RPM side. We now reach the high stop and are about 1/8" off the low stop. Torqued and safety wired the governor.
 
I've got the control cable going to the Governor working well and the routing under
the engine nicely aligned so that it doesn't touch the sump. I've got a
question regarding the control throw limits, though. Right now at HIGH RPM, the
control on the Governor is hitting the stop as it should. No problem there.
However, on full LOW RPM, I'm about 1/8" away from hitting the stop on the
Governor. I've fiddled around with the available adjustments 'til I'm blue in
the face and I just can't get that last little bit of LOW. Given the angle of
the bracket, its kind of a pull backwards for the pushrod so its just never
really going to work with the current bracket. My question is this: Does it really
matter? When what the last time anyone actually had full LOW RPM setting?
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Matt G Dralle | Matronics | PO Box 347 | Livermore | CA | 94551
925-606-1001 V | 925-606-6281 F | dralle(at)matronics.com Email
http://www.matronics.com/ WWW | Featuring Products For Aircraft
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