Today's Message Index:
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1. 11:25 AM - Thrust line (posting for a friend) (chic)
2. 01:42 PM - Re: Going to a 72" prop (Richard Pike)
3. 07:58 PM - Re: Kolb-List Digest: 2 Msgs - 03/30/21 (artdog1512)
Message 1
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Subject: | Thrust line (posting for a friend) |
Hello chic.
Would you mind posting this message for me? I seem to have lost my ability to
get replies in although I receive the digest. Thanks.
What you said is absolutely true about pointing the thrust line down. Maybe most
pusher owners know this but I didn't and I didn't think it was intuitively
obvious that pointing the thrustline down would add up thrust.
When I purchased this pusher with an 80 horsepower 912, both the owner and the
builder said that it had issues with an inability to trim at high power settings
and difficulty in rotating on takeoff without easing off on power. They thought
I should be going back to a lower powered engine.
I looked at it and thought the engine was pointing down too much and so raised
the thrust line to compensate. That caused so much back pressure on the stick
that I could barely complete the flight even with full up trim. It was then I
started digging around to find out how things really worked and the best source
of information aside from a couple of people who knew what was going on, was
at model airplane sites which had good diagrams showing the effect of thrust
line relative to the centre of gravity. This got me adding down thrust and I
now have, after about a 6 degree change, an aircraft where I can go from low-power
to full power with no change in trim on the stick.
Mine was the first and maybe only one with a 912. Aircraft is a Skywatch.
Peter
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=501169#501169
Message 2
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Subject: | Re: Going to a 72" prop |
All done and flying great. Had a few teething issues:
Initially started out with an extra 3/8" motor mount spacer at the rear, giving
it a bit of downthrust to counteract any possible pitch over tendencies. Flew
it four times that way, evaluating handling while trying to get the Warp Drive
prop pitched properly. (Made me really appreciate the Ivo's ultra simple prop
adjustment method!)
Short version: the airplane simply felt wrong. Constantly fighting it as it kept
trying to nose up at most every throttle setting, plus on final with minimal
power, it just did not feel right.
Removed most of the rear spacer, now it handles just like it always did, deviation
from stock thrust angle is two extra 1/16" washers on top of the rear Lord
mounts.
Spent one afternoon playing with brass shim stock between the prop hub and the
gearbox prop flange, finally got all three blades tracking within 1/16" of each
other.
Spent several days trying to get the prop pitched for a 6300 rpm climb and a 6500
rpm max in level flight. Finally got within 50 rpm and called it quits.
Plugs look good, EGT gauges were lying to me. The new dual EGT gauge arrived today,
no hurry putting it in, wx is rainy today, uber windy tomorrow.
Anyway, everything is now as it ought to be, it runs smoother than it ever has,
and the climb rate is typically right at 1,000'/min solo. Looks like normal cruise
is going to be about 53-5400 rpm at 65 mph. And boy is it quiet!
Now I need a pretty day so I can take some pictures of that old 2-seater trike,
it's 582/w electric start, B box, BRS, and my 68" Ivo, get that thing sold and
out of the hangar. $3k if you guys know anybody looking for such.
Thanks for the suggestions & advice along the way.
--------
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=501172#501172
Message 3
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Subject: | Re: Kolb-List Digest: 2 Msgs - 03/30/21 |
Time: 05:29:33 PM PST US
Subject: Kolb-List: Re: too fat .....
From: "chic" <gcechini@msn.com>
Your biggest issue with the Firestar 2 and a heavy pilot is going to be a f
ar forward
CG.We have the same problem. I have a FIrestar 2 and I weigh 250 and am
6'4". How big are you?
i'm 6ft... i have only one seat in the cockpit. (2) 5 gallon tanks under th
e engine. i just wondered what the maximum weight is for the cockpit? .....
......... i figured that since the FS 2 is made for (2) people one heavy pe
rson shouldn't be a problem with weight and balance.. i don't know=C2-
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