REFLECTOR: Back in the air.

[Chuck Jensen]

Hiroo,
 
It sounds like you are getting some quality time on the bird.  Regarding
the hot C#6, of course, it may be a cooling/baffling (well, actually its
always baffling, but of a differently type) issue.  However, another
possible cause is if you are running rich of peak, #6 by be way leaner
than the other cylinders so while they are running ROP, #6 is running
right at peak EGT/CHT temps.  Or, if you have engine instrumentation for
each cylinder and you are running lean of peak, then perhaps #6 fuel
mixture is way too rich.  In this case, as you bring the other cylinders
to LOP, it leaves #6 right at peak temperatures.
 
Air flow/cooling may be the most obvious cause of hot temps, but since
its isolated to a single cylinder, there are a couple other possible
causes, such as fuel/air mixture to that cylinder.  Just another thought
to noodle over.
 
Chuck Jensen 
 
 
 -----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Hiroo Umeno
Sent: Sunday, May 27, 2007 9:36 PM
To: Velocity Aircraft Owners and Builders list
Subject: REFLECTOR: Back in the air.



Yesterday, after many thwarted attempts and frustrating weekends staring
at the sky, I was able to bring N21HV back in the air.

 

Take off was at 1:10pm.  After staying close to Paine to verify that all
systems were running temps were in the reasonable range, I took the
plane through some "cruise" configuration tests over Puget Sound.  The
flight prior to this in September was with the Mid-CG configuration with
60lb ballast on the co-pilot seat and the additional 30lb of lead-shot
in the nose.  Yesterday was a aft-CG test without the 60lb ballast
keeping the 30lb in the nose, full tank of gas.  This simulates the
single-pilot X/C load-out.

 

Some numbers in case anyone cares<g>.  (Performance data based on data
capture from the EFIS)

Take-off Weight: 2011lb (2400 Gross)

Take-off CG: 121 (115 - 121 allowable)

Initial Climb:  1800fpm at 2424ft DA, 2430rpm, 27.5in/Hg on the MAP,
100Kts

Cruise: At 6000ft DA, 2650rpm, 20.6in/Hg MAP, 152Kts TAS, 8.0Gph burn
rate.

 

The plane is currently in the "Dirty, no-pants" configuration where all
the aerodynamic trims, fairings, and wheel covers are still off which, I
am told, will add another 15Kts or so.  At this point, I haven't been
able to test the wide open throttle since the CHT is still running
hotter than I would like.  I have 13 hours on the engine so far and my
engine guy tells me that it will run hot until all the rings break in.
It does bother me a bit that #6 CHT stays consistently hotter than the
rest, though.

 

I did a somewhat rectangular leg of W10 - BVS - FHR - 0S9 - W10
including some dodging of occasional wispy layers here and there.  Over
South Whidbey, I did some low-speed work like MCA, Pitch-Buck, etc.  On
pitch-buck, with the CG fairly close to the aft limit, I ran out of the
elevator travel at 75Kts and the aircraft settled onto steady, mushy
descent.  Noticeable pitch buck never occurred.

 

Back at Paine, I did a few touch-and-go's, all were fairly good.  On the
last landing, (full-stop) I was able to slow the plane down to taxi
speed a bit past A6.  If I can consistently nail this one, I can bring
my personal minimum runway length to 3,000 from my current 4,000.

 

Overall, very good flight.  2.5 hours on Hobbs.  13.9 TT airframe
cumulative to date.  It's a nice flying machine!

 

 

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