REFLECTOR: Yet another taxi test!

Jeff Barnes jcbarnes411 at sbcglobal.net
Tue Sep 15 21:56:33 CDT 2009


Hi Scott, 
 
    On #3, check your NG at the hinge point make sure no cracks on suppporting structure. Also, do you have latest NG from factory ?   Check Rich Guerra's website for 'Oshkosh Miracle' pictures and look at his: If yours is like that, it should be replaced.
 
    Congratulations on progress, and way to go in catching and stopping that fire. Another 30 seconds and you could've had a meltdown !  A lesson for us all to get out and inspect immediately.
 
Regards,
 
Jeff Barnes  

--- On Tue, 9/15/09, Scott Derrick <scott at tnstaafl.net> wrote:


From: Scott Derrick <scott at tnstaafl.net>
Subject: REFLECTOR: Yet another taxi test!
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Date: Tuesday, September 15, 2009, 9:05 PM


Today's taxi test went way better than the last one!

82 degrees,  5-10 knot crosswind.  Density altitude 9400 ft.

After putting drain holes and drain valleys/dams in the lower
cowling/scoop,  cleaning things up, and fired her up for a short 2
minute run.  Ran well, no leaks.

Put cowling back together, whist  taking pictures.

Fired up again for an extended full throttle run until cyl head temps
reached 350, that was a few minutes at full throttle.

Looked like she was ready.

First taxi run was a 50 knots, no problems.  Static RPM is still
pathetic at 2050-2100 and it did take longer than I thought it should to
get up to 50 knots.  I forgot how hard you have to press the brakes to
get any real breaking!  Got used to the 210's brakes which are mighty
touchy.

Turned around and got up to 60 knots, everything felt fine,  nose just
starting to want to fly.   Cyl head temps were around 350, oil at 200 by
now.

Pulled off taxied back to hanger and shut down.  Walked around looked
everything over, nothing loose, no visible leaks.  Let her sit for 20
minutes.

Fired back up, taxied to runway,  cyl temps 280, oil 190

Got up to 70 knots, nose coming up with just a touch of back pressure,
held up for 2,000 ft, coasted to a stop, oil was now at 225, cyl temps 360

turned around, got up to 70 knots again, held nose in takeoff attitude
for 2-3 thousand ft.  oil at 240 now, cyl temps 365

Then the fit hit the shan!  After letting the nose back down, slowing
through 50-45 knots, nose wheel shimmy!  Wow!  I hate that! This is the
second time I've felt in in 450 hours. I applied max brake and at about
20 knots it stopped. 

Taxied back to hanger.  I will be de cowling Thursday and doing a
thorough inspection  to  verify everything is OK.

3 possible problems.

1.)  high oil temps?  Should I expect that when doing these taxi tests? 
I know if I had actually taken off, the nose oil cooler would have
really started to work with the higher air speed...  Anybody else see
similar temps when taxi testing with a already hot engine?  I have to
say I have a fan driven secondary oil cooler which I neglected to turn
on until right before the last run.  Needs to be added to my checklist!

2.) low static rpm.  Its not so low I can't fly, but it really seems
like it should be in the 2200-2250 range. I never saw higher than 2050. 
I will call Catto tomorrow afternoon and see what can be done.  I've
already sent it back twice for tuning. 

3.) Shimmy, just need to tighten the washers.  When I got back to the
hanger the fork was loose?  I've never had it loosen up like that
before?  Maybe after sitting for two years, I don't know...

Any thoughts about any of the 3 issues?

Scott




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