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To: flyrotary@lancaironline.net
Date: Sun, 20 May 2007 09:45:27 -0700
Subject: Re: Marginal Cooling contributes to Crash.
Message-ID: <20070520.094538.2604.3.alwick@juno.com>
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From: al p wick <alwick@juno.com>

I'll try one more time. 

I posted a response last week. The purpose was to improve the safety of
all the flying aircraft. No other purpose. It involves some experimenting
and measurements you guys have never done before. Let me explain. 

We know that the cooling efficiency of all the flying rotaries follows a
"normal" distribution. Please note, I'm using the term efficiency. So
that eliminates radiator size and air flow area from the equation. So if
we have 100 guys flying rotaries, we know there are 5 guys who have way
better cooling than the others. We also have 5 guys who have way worse
cooling. I think Ed described one of those guys in post earlier...the one
with smoking engine on shutdown.  Some of you may not be familiar with
this "normal distribution" concept. Basically, all things follow a bell
curve naturally. 95% of the guys flying have very similar cooling. But
there are always a few that have way better efficiency. Who are those 5
with better efficiency? What are they doing different? We don't know for
sure. Could be one of them has this little piece of sheet metal in his
duct that improves air flow. Could be they all have radiator type X with
different fin spacing.

How do we find those 5 guys? The normal sharing of info you guys do
doesn't cut it. This is because we have a lot of variables affecting the
results. So I suggested an experiment. We eliminate some of those
variables so that we can find those few. 
1) You measure your radiator fin area, both coolant and oil. Measure
outside air temp. 
2) You use duct tape for experiment to reduce every one's cooling to the
same area. 
3) You climb out at the same airspeed. Let's say 90 mph. Perhaps repeat
at different speed. So everyone is producing the same hp from 0 to 12k
ft. 

This gets you very close to apples to apples comparison. Those 5 guys
will outperform the others. This test does not eliminate all of the
factors, so it would still need you to estimate air flow area or drag. I
haven't thought of everything here. You guys could improve the test. Just
throwing out the concept.

You know those 5 guys with really bad cooling? They couldn't do the test.
They would be at risk of overheating. So if you guys agreed that 100 Cu.
In. was target rad area, you would want to start out taping off only
small portion of rad. Test. Then finally move closer to 100 cu. in. if
your tests indicate it's safe.

BTW, clearly John, with turbo engine, there is always a point where you
have to make temperature decision. You have way more hp than needed for
departure. So I agree with you. I was wrong in that respect. However, I
still encourage seeking the cooling efficiency improvement. So if you now
climb out at 150 mph at 220F, we want to try to get that to 210F. Just by
taking advantage of those 5 guys.

Clearly someone's going to read this and take offense. If so, take a
couple valium. Wait 24 hours, read again, and see if you can find some
positive intentions in this. Sheez.


-al wick
Cozy IV powered by Turbo Subaru 3.0R with variable valve lift and cam
timing. 
Artificial intelligence in cockpit, N9032U 240+ hours from Portland,
Oregon
Glass panel design, Subaru install, Prop construct, Risk assessment info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html


On Sun, 20 May 2007 09:19:24 -0400 John Slade <sladerj@sbcglobal.net>
writes:
>  >The root cause of problems in the activity is the activity itself. 
> 
> ..... If you can't put numbers on the design criteria then nothing 
> can 
> be produced to meet them, nor is there the possibility of >a test to 
> 
> determine if it meets the criteria.
> Nicely said, Ernest. A useful discussion might concentrate on 
> definition 
> of the objectives.
> Rather than be avoided, I'd suggest that "Marginal" is to be sought 
> 
> after  - the ideal. Everything is a compromise. Make the cooling 
> adequate for full power low level and you give up advantages in 
> other 
> flight regimes. (speed).  I don't think I've ever used full power 
> except 
> occasionally on take-off. I fly on the temp gages and don't see 
> anything 
> wrong with this. To cool at full power under all circumstances I'd 
> have 
> to add scoops and drag that would probably reduce high altitude 
> cruise 
> speed by maybe 30 kts. This is not acceptable. A compromise is the 
> best 
> answer here.
> 
> Here's my definition for an adequate cooling system :
> Pick your max operating ground level OAT - I used 96F.
> 
> Able to maintain oil & coolant temps at idle / minimal rpm on the 
> ground 
> at 220F or less indefinitely  (you could put a time limit on this 
> one)
> Able to take-off and climb to patten altitude at or below 220F, then 
> do 
> it again within 2 weeks (ideally twenty minutes)
> Able to cool to below 220F when throttled back on downwind
> Able to maintain oil and coolant at or below 220F while climbing to 
> 
> altitude at >= 1000 fpm
> Able to cool at or below 220F during high speed high altitude cruise 
> for 
> the aircraft in question.
> Able to cool at engine ideal (185F?) during standard cruise altitude 
> and 
> speed / for that pilot / aircraft / usual location.
> 
> This definition is for an aircraft like a Cozy with a specific 
> mission - 
> high speed travel.
> The definition might well be different for an aircraft with a 
> different 
> mission - short field take off / aerobatics / crop spraying etc 
> etc.
> 
> Regards,
> John Slade
> Turbo Rotary Cozy IV
> 87 hrs., all marginal.
> 
> 
> --
> Homepage:  http://www.flyrotary.com/
> Archive and UnSub:   
> http://mail.lancaironline.net:81/lists/flyrotary/List.html
> 
> 


-al wick
Cozy IV powered by Turbo Subaru 3.0R with variable valve lift and cam
timing. 
Artificial intelligence in cockpit, N9032U 240+ hours from Portland,
Oregon
Glass panel design, Subaru install, Prop construct, Risk assessment info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html