REFLECTOR: Ground Testing Update
Laurence Coen
lwcoen at hotmail.com
Mon Feb 18 16:28:39 CST 2013
Brian,
I have a plain vanilla Franklin and a pair of slicks for ignition. The IVO
is set with just one washer on the fine pitch side. Take off roll with a
first time passenger often gets a remark to the effect of " Wow this thing
really accelerates". If it don't push you back in your seat it isn't
working right. You should see close to 2450 RPM static. I see 80 knots in
about 1500 ft of ground roll.
Peak power should be about 100 F ROP. When it comes to experimental, "You
da man".
Larry Coen
N136LC
--------------------------------------------------
From: "Brian Michalk" <michalk at awpi.com>
Sent: Thursday, February 14, 2013 10:09 PM
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Subject: REFLECTOR: Ground Testing Update
> It's been quiet here, so here's something to fill the void.
>
> I've been on the cusp of my second first flight for almost four months
> now. Man, it's been a long time. My primary problem is that I just
> haven't been able to make rated horsepower, and it's been due to three
> reasons.
>
> 1. The impulse coupler spring on my magneto broke.
> I ordered a spare alternator, and it was about 40 days from ordering to
> delivery. I continued to do ground testing with the bad coupler, knowing
> that the timing was anywhere between 0TDC and 32 TDC.
>
> 2. The mixture was too rich.
> I spent about four hours tuning the engine in November, starting over from
> scratch on the electronic tables that map RPM and manifold pressure to a
> fuel flow. If you recall, my first flight four years ago was due to an
> over-rich condition. Well, I tuned to 50F ROP. After I got the magneto
> in, I still couldn't make power. I brought the plane back and ran static
> at full throttle, leaning out the mixture. Sure enough, the RPM's came
> up, so I tuned to max RPM, then richened until the RPMS dropped slightly.
> This should be a safe mixture for the first flight. It turns out that I
> have my engine monitor set for Celsius instead of Fahrenheit.
>
> 3. The turbo is seized.
> This is the final discovery made this weekend. It's either spark, fuel or
> air, and this was the final problem I hope. About 20 engine hours ago I
> put a restriction in the oil line to the turbo to keep from blowing oil
> through the seals. Apparently my calculations for the restriction are
> wrong. I pulled the turbo and sent it out for repair, estimated to be
> about $350.
>
> It's been very frustrating. I have been set up for my "first flight" on
> about four different occasions, only to shut her down in the takeoff roll
> because of not accelerating through 80 knots. I've had the plane very
> light on the wheels. Nose up, one or the other mains up, but no
> acceleration through rotation. I bet I've gone through 15 to 20 high
> speed taxis like this, and I'm ready to just fly the airplane. This turbo
> problem better be the solution. I'm out of ideas if it's not. On the
> first flight four years ago, there was plenty of power. Same fuel system,
> induction and ignition, so I know the engine is capable of making the
> power.
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