REFLECTOR: Flight testing going well...18hrs in, new video

Thu Sep 27 11:12:28 CDT 2012

Scott,

Thanks for the info on reaming out an injector.  I looked at the price of a
new injector - wow!  I will be careful.  When I'm trying to go LOP, the
issue I have is that #3 is first to peak and when its at 50F LOP, the
others are at 20F or so (this difference varies with altitude).  When I get
the others to 50F, I can feel it starting to get a bit rough as #3 is
likely getting too lean.  #3 is always running leaner than the rest.
 Hopefully a good cleaning will help out, but if not, I'll try, as you say,
"burnishing" it out by twirling a smaller-size drill bit.

Geoff

On Thu, Sep 27, 2012 at 12:02 PM, Scott Derrick <scott at tnstaafl.net> wrote:

>  yeah the important point about EGT's is that their relative temps in
> relation to PEAK are the important data points.  Probe location and wind in
> the cowling can really skew the absolute temps, except for redline temps.
> You don't want to run your egt's above red line very long.
>
> If your hot cylinder is still ROP when all the rest are well past PEAK and
> running LOP that could cause the problem you are seeing.  Opening up the
> injector would only worsen the problem.
>
> BTW be very very very careful opening up the injector.  You basically
> burnish not drill. The difference in size between sequential injectors say
> a D12D to a D12E, one step in size, is less then the difference in size
> from a numbered 72 to a numbered 73!  You always select a drill smaller
> than the injector opening and then spin it by hand(NOT IN A DRILL MOTOR) a
> few times. Very easy to open them up to much, and then your *****ed.  I put
> the drill in a vise and spin the injector. Go from both sides, then blow
> out, then inspect very carefully to verify no bits of anything are in the
> injector.
>
> Scott
>
>
> -------- Original Message --------
> Subject: Re: REFLECTOR: Flight testing going well...18hrs in, new video
> From: Jack Prock <jackprock at wavecable.com> <jackprock at wavecable.com>
> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org><reflector at tvbf.org>
> Date: 09/27/2012 09:44 AM
>
>  Hi Geoff,
>
>  Before you go chasing the EGT on one cylinder, you should watch
> http://www.eaavideo.org/video.aspx?v=1316946190001
>  He gave a talk on EGT’s at Oshkosh that was very interesting. It was
> about the mistakes people make with EGT’s and what
>  they really mean if anything. If your CHT’s are fine, you should be
> fine.
>
>  It is a bit long, but I highly recommend it before you start ripping
> things apart.
>
>  Jack
>   *From:* Geoff Gerhardt <geoff.gerhardt at gmail.com>
> *Sent:* Thursday, September 27, 2012 4:31 AM
> *To:* Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> *Subject:* REFLECTOR: Flight testing going well...18hrs in, new video
>
>  Guys,
>
> Flight testing is going well, I've got about 18hrs in.  I'm still not able
> to just go out and fly - always little fixes and tweaks (that's the fun
> part for me, tho).  I have learned, tho, not to immediately try to correct
> an issue, but learn more about it first.  I've been chasing a hot cylinder
> and have been trying to cool it with better airflow.  After reviewing data
> logs and confirming it on my last flight, I now realize that its likely a
> combustion problem.  The EGT for that cylinder is always high.  Because of
> my aggressive airflow modifications, even in spite of that high EGT, the
> CHT is ok now.  I'm going to pull out the injector nozzle this weekend and
> give it a good cleaning.  If that doesn't work, I may try to ream it out a
> little.  I tried to put an oil collection reservoir as I was tired of
> wiping oil off the cowling, but it introduced too much back pressure, and
> all of a sudden I had a bunch of oil leaks to deal with (a rather nasty
> surprise of seeing oil all over the inside/outside of the cowling after a
> 2.5hr flight).  Got all those cleaned up and removed the oil recovery
> system.  I think I'll try to vent the breather into the exhaust.
>
> Other than those issues, its been going pretty well.  I've been playing
> with fuel settings, altitude and efficiency.  I typically head up to
> 8-10,000' and run LOP.  At 10k' I am usually ~150ktas, and 8gal/hr.  I love
> the high-speed descent into the airport.  I report 10mi out to the tower
> and I'm in the pattern in no time - I think they're getting used to me
> zipping in as opposed to the C172's and warriors they're used to.
>
> Here's a recent video I took taking off with a belly-mounted camera
> looking back.  Its kinda neat in that it looks like I'm zooming the lens as
> I gain altitude.  Yes, I know, it takes me a long time to get off the
> ground.  I actually have another prop coming that might help.  A Cozy owner
> had a left-turning Catto that he no longer uses.  Its a 64x76, mine's a
> 66x74.  I suspect it'll get me off the ground much quicker.  He didn't want
> much for it, so it'll give me a backup - I'll send mine back to Catto at
> some point to get it repitched or just keep it for a long-range cruise prop
> as it is.
>
> Geoff
> (I uploaded it in high-res so make sure you switch to 1080p)
> http://www.youtube.com/watch?v=JhNZBc-inbw
>
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