REFLECTOR: Power setting gouge: First Flight

[Chuck Jensen]

Terry,
 
15 x 2300 gives me approx. 100 kts with the gear down with the same engine.  I would think 23 x 23 will give you right at 140 kts +/- a little.  Not to complicate things, but I believe that keeping the manifold pressure up and rpm down will aid in keeping pressures high in the cylinders to allow the rings to seat properly.  Any thoughts on whether 24 x 21 is better by anyone?  As a side benefit, the lower RPM will reduce piston friction a little which slows heat build up.
 
Long term, Aviation Consumer's study indicates its better to run low MP and high RPM.  Cylinder and ring wear is more associated with cylinder pressures than piston speed.  However, during breakin, where there is a desire to run at as high a power level as possible, these conditions are reversed.  Just a thought.

Thanks, 
Chuck Jensen 

Diversified Technologies 
2680 Westcott Blvd 
Knoxville, TN  37931 
Phn:    865-539-9000 x100 
Cell:    865-406-9001 
Fax:     865-539-9001 
cjensen at dts9000.com 

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On Behalf Of Terry Miles
Sent: Thursday, November 01, 2007 8:17 PM
To: 'Velocity Aircraft Owners and Builders list'
Subject: REFLECTOR: Power setting gouge: First Flight



Hi all,

 

My question is to anyone flying the 300 hp version of the XL. 

 

 I need to know in an XLRG at 5000 msl,  will it stay below 140 kts, with the gear down at 23 x 2300-aprox 65% power.  

 

 

Here is the issue:

 

 

I am up to the flight test phase.  Scott Swing told me last week if I take the main gear doors off, I could go to 140 kts or so with the gear down   I have a zero-time Don George rebuilt 300 HP Ly IO-540K, w/ a 3 bladed, controllable pitch. Aerocomposite Inc. prop.   

 

One school of thought says don't raise the gear, but I want to keep a high MAP (at least 65%) for 30 mins or so to begin the process of seating the rings.  That's if no other first flight issues require a return to base.  

 

The other option obviously is to raise the gear on the first flight which will take me to cruise speed regime at 5000' and 65% power.  I would the speed increases pausing at 10 knot intervals.

 

Anybody been down this road, flight testing a new airplane with a newly rebuilt engine?

 

Thanks,

Terry

N821TM

Airworthiness Inspection complete!

 

 

 

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