REFLECTOR: Annual inspection/Compression Checking.

[Terry Miles]

Safety issues:
I'll add in some on this, since I think I started it.  My compression check
was done with a local IA and myself.  He had the compression checker.  I
just bought one from Spruce and it arrived yesterday.  The air line is too
short in my opinion.  I am going to lengthen it so the air gauge checker can
stand outside and fully free of the prop arc.  The blade holder guy should
stand aft of the prop so he can step free if anything goes wrong. 

Remember if you ask for local help it is entirely possible your help will
never have worked with a pusher which means being held between the trailing
edge of the wing and the prop arc to get to the cylinders.  
Terry 

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Dave Philipsen
Sent: Thursday, September 11, 2008 1:52 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Annual inspection/Compression Checking.

My bad.  You guys are right.  I guess I was mentally trying to prove why 
you don't feel that much pressure on the prop blade if the piston slips 
off center.  And I guess the real reason is that as the prop blade rests 
on your shoulder it is likely much farther from the center of the 
crankshaft than the point at which the piston is pushing on the crankshaft.


Doug Holub wrote:

If the piston were 132 mm in diameter (5.2 inches), and the air pressure was

0.124 psmm (80 psi) the force on the piston would still be 1698 pounds.



Keith Hallsten wrote:
> Pounds / square inch x square inches = pounds.
>
> Pound / sq in x sq mm = gibberish
>
> Keep the units consistent and you will get real answers.
>
> Keith
>  
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> Behalf Of Dave Philipsen
> Sent: Wednesday, September 10, 2008 7:19 PM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: Annual inspection/Compression Testing.
>
> There is nothing in your formula that quantifies the area over which the 
> 1698 lbs. is spread.  Using your formula, I could say that the piston is 
> 132mm in diameter in which case:
>
> 13,701.4 sq mm @ 80psi=1,096,112 lbs. force
>
>
> HYTEC45 at aol.com wrote:
>   
>> In a message dated 9/10/2008 11:51:59 AM Pacific Daylight Time, 
>> davedent at comcast.net writes:
>>
>>     Remember you are putting 80psi against sometimes a surface of 5.2"
>>     and that's a lot of area to stop. 
>>
>> 21.23 sq inch.  @ 80psi=1698lbs force.
>> TEC 
>>
>>
>>
>>     
>
>   

-- 
Dave Philipsen
Velocity STD-FG
N83DP

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