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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