REFLECTOR: Yet another taxi test!

[Scott Derrick]

Thanks Bill,

I think checking the timing is in order. 

The low static is with full throttle and the mixture set for best
power.  Our high density altitude has some effect on static rpm, I'm
just not sure if it should effect it that much.

I thought the high oil temps might be because of the extended full power
runs with very little air through the oil cooler.  I've never made so
many high power runs so close together with out actually flying.

Scott

Stockman, Bill wrote:
> Oil temps--don't worry since you were taxing around and running on the runway at full throttle, wait until you see what you get in an extended climb or cruise.  With two coolers that should resolve itself.
> Shimmy--if you’re a FG, make sure you have the new rubber shock absorber installed, then check nut tension and air pressure.
> Static RPM--likely is the prop, I ended up getting a different prop from CATO and rpm jumped 200 revs.   Now I have a range of about 2275--2750 (+/- 25 rpm).    If not the prop, check your timing and fuel servo and inlets.
>
> Bill Stockman
> Senior Associate
> Dayton Aerospace, Inc.
>
> 937.426.4300 W
> 937.369.4799 C
> bill.stockman at daytonaero.com
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Scott Derrick
> Sent: Tuesday, September 15, 2009 10:06 PM
> To: Velocity Aircraft Owners and Builders list
> Subject: REFLECTOR: Yet another taxi test!
>
> 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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