REFLECTOR: Back in the air.

[Andy Millin]

You may want to swap the sensor on #6 with another cylinder for a flight.
Make sure the sensor is in line with the others.
 
Thanks for the update.  It is good to hear you are back in the air.
 
Andy

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Hiroo Umeno
Sent: Monday, May 28, 2007 11:22 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Back in the air.



Good thoughts on the mixture.  I didn't mention it in the original post but
I did suspect something like that and I kept an eye on the EGT through the
flight.  The EGT was generally in line with the rest so I definitely think
it is an airflow issue.  I'll have to see if the "rubber seal" under the
cowl is leaking or not.

 

My plane does not have the conventional fiberglass box over the top of the
engine.  Instead, the whole upper cowl area is pressurized through ram air
from the top NACA and I have metal baffles around the entire top with rubber
flaps sealing the gaps between the baffles and the cowl.  If it isn't
leaking, I might need an additional arrangement to direct more air over to
that corner.  It is interesting that the #5 on the other side has no
problems.

 

Hiroo

 

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Chuck Jensen
Sent: Monday, May 28, 2007 7:27 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Back in the air.

 

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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