Today's Message Index:
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1. 11:56 AM - Engine down thrust angle (Gary Vogt)
2. 12:06 PM - Re: Engine down thrust angle (n26390@AOL.COM)
3. 12:38 PM - Re: Engine down thrust angle (Gary Vogt)
4. 05:08 PM - Re: Engine down thrust angle (FLYaDIVE)
Message 1
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| Subject: | Engine down thrust angle |
I'm doing an annual on a Tiger that came in with the engine visibly too far up.
I measured the angle: .8 degrees up. The bottom mounts had two shims each.
I
removed one each of the bottom shims. The engine is now at .3 degrees up.
RIght now, there is one shim on each mount.
Note: This plane just had a new engine installed. During the engine overhaul
period, the engine mount was sent to Kosola Engine mounts for overhaul and
painting. The installation also got all new -59 engine shock mounts.
The cowling is still below the spinner (i.e., spinner is higher than the
cowling.) It could still use an extra shim in the top mounts; that would make
two each on the top mounts, just like mine with the jaguar cowling.
Message 2
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| Subject: | Re: Engine down thrust angle |
Gary: Aside from the mismatch between the cowling and spinner, what is the
effect on performance/groundspeed of too much angle up or down?
Thanks,
Roger Rucker
AA5A '78 HWO
-----Original Message-----
From: Gary Vogt <teamgrumman@yahoo.com>
Sent: Thu, Feb 10, 2011 2:57 pm
Subject: TeamGrumman-List: Engine down thrust angle
I'm doing an annual on a Tiger that came in with the engine visibly too far
up. I measured the angle: .8 degrees up. The bottom mounts had two shim
s each. I removed one each of the bottom shims. The engine is now at .3 d
egrees up. RIght now, there is one shim on each mount.
Note: This plane just had a new engine installed. During the engine overh
aul period, the engine mount was sent to Kosola Engine mounts for overhaul
and painting. The installation also got all new -59 engine shock mounts.
The cowling is still below the spinner (i.e., spinner is higher than the co
wling.) It could still use an extra shim in the top mounts; that would ma
ke two each on the top mounts, just like mine with the jaguar cowling.
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Message 3
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| Subject: | Re: Engine down thrust angle |
>From what I've found on the internet, a down thrust angle is preferred over an
up or zero thrust angle. With a down thrust angle, there is less requirement
for pitch changes with throttle changes. I have also noticed there is less
requirement for elevator down (nose down) with an engine down thrust angle.
That in itself should lessen overall drag.
________________________________
From: "n26390@AOL.COM" <n26390@AOL.COM>
Sent: Thu, February 10, 2011 12:03:57 PM
Subject: Re: TeamGrumman-List: Engine down thrust angle
Gary: Aside from the mismatch between the cowling and spinner, what is the
effect on performance/groundspeed of too much angle up or down?
Thanks,
Roger Rucker
AA5A '78 HWO
-----Original Message-----
From: Gary Vogt <teamgrumman@yahoo.com>
Sent: Thu, Feb 10, 2011 2:57 pm
Subject: TeamGrumman-List: Engine down thrust angle
I'm doing an annual on a Tiger that came in with the engine visibly too far up.
I measured the angle: .8 degrees up. The bottom mounts had two shims each.
I
removed one each of the bottom shims. The engine is now at .3 degrees up.
RIght now, there is one shim on each mount.
Note: This plane just had a new engine installed. During the engine overhaul
period, the engine mount was sent to Kosola Engine mounts for overhaul and
painting. The installation also got all new -59 engine shock mounts.
The cowling is still below the spinner (i.e., spinner is higher than the
cowling.) It could still use an extra shim in the top mounts; that would make
two each on the top mounts, just like mine with the jaguar cowling.
st" target=_blank>http://www.matronics.com/Navigator?TeamGrumman-List
p://forums.matronics.com blank>http://www.matronics.com/contribution
Message 4
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| Subject: | Re: Engine down thrust angle |
Gary & Team:
>From my experienced down thrust is a good thing ... IN MODERATION.
- There is a down thrust on the elevator to keep the nose up and that is
created by the air flow.
- There is a lateral pivot point which balances down thrust of the
elevator against down thrust of the engine.
- AND this is a BIG ONE - It is much easier to land a plane with
down-thrust to an engine than one with up-thrust. With up-thrust you have
to fly the plane onto the runway. SO, what happens with ZERO Thrust?
- There is more of a neutral feel and WHICH I PREFER - And when power is
cut there is only a small pitch change.
- With Up-Thrust when the power in cut the plane wants to DIVE - Since a
lot of down elevator is used to keep the plane S&L. So what happens with
Down-Thrust?
- When the power is cut the plane will start to balloon just a little...
Most people will not even notice it. And in many cases you will already be
trimmed very close to best glide SO there is less work to do when setting up
for a landing.
- NOW! ALL this information is dependent on HOW MUCH thrust we are
talking about.
- If the feel is that noticeable you have some major thrust errors to
correct.
Barry
"Chop'd Liver"
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