From: Epijk@aol.com
Message-ID: <167.a4061ef.29c0f2d4@aol.com>
Date: Wed, 13 Mar 2002 13:22:12 EST
Subject: Re: Supercharger system
To: Lancair.list@olsusa.com
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Reply-To: lancair.list@olsusa.com

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George, Fred and Brent:

The responses to your thoughtful and educated 
suggestions to the "supercharger" project should 
only serve to convince you further what an utter 
waste of time it is to offer facts, engineering, and 
experience into the world of wishful thinking 
and perpetual motion.

<<<...Right now @ 42in. MAP our inlet temp is 
150F so I do not see a need for coolers yet on 
the Normalized version...>>>

AHA, someone has (yet again) repealed the fundamental 
laws of thermodynamics. 

Although a multistage axial compressor can be more 
thermally efficient (85%)  (oops, 0.85 for Eric) than the 
best of the single-stage centrifugal compressors such 
as found on turbochargers (typically around 75% in a small 
operating-efficiency island), the temperature-rise numbers 
assuming hot-day inlet-air (as they do for certification) 
suggest that 150F cylinder-inlet temperature at 
42" MAP might be the product of faulty instrumentation. 
But hey, real data might burst the bubble.

<<<...Testing as you know tells all...>>>

Actually, testing DOES NOT tell all. 
Testing proves only the EXISTENCE of flaws, 
not the absence, of flaws. 

<<<...But in normal operation you do not run 100% power at high 
flight levels and therefore the heat is less of a problem than 
you state...>>>

I don't recall Fred suggesting that the problem was limited to
the regime of 100% operation. The problems Fred described
have been experienced, documented and worked-on by
real engine experts, but hey.....

As you probably suspected, George, all those people 
who have worked on reducing the detonation-sensitivity 
of the TIO-540's and GTSIO-520's (Chieftan, P-Nav, 421, 
AC-685, etc.) must have had no grip on what they were 
doing, because they found that, with inlet air temps of 
150F (and EXTERNAL-SURFACE CHT's above 400F) 
there was a distinct propensity for destructive 
detonation, which they could only remedy by 
calibrating in fuel flows which produced BSFC's 
of 0.7 at high power operation.

<<<...we are going to photo the panel on all flights 
for data storage...>>>

During the flight test program for the STC-engine retrofit 
of the Orenda V8 into the Aero Commander 685, I found 
that the only reasonable way to collect comprehensible 
flight test data (with sufficient detail and real-time 
correlations to actually troubleshoot problems instead 
of guessing)  was with a computerized data acquisition 
system. 

I put together a system which took inflight data readings
at one second intervals, then downloaded the data 
(postflight), post-processed the raw data to 
produce flight data and engine data, and produced both 
onscreen and hardcopy graphical (trend analysis) and 
numeric data from the flight. 

The raw data recorded were: Pitot pressure, Static pressure, 
OAT, MAP, RPM, Compressor Discharge Temp & Pressure 
(CDT, CDP), Intercooler Discharge Temp & Pressure 
(IDT, IDP), air-delta-P and delta-T across all 3 heat 
exchangers (Coolant, Oil, Intercooler), fluid delta-P and 
delta-T across all 3 heat exchangers, oil pressure, oil temp, 
coolant pressure, coolant temp, all 8 EGT's, TIT, 
turbochanger RPM, pilot-inpit "MARK" button, 
and 3-axis accelerations. (a bit more than is likely 
to be available on the instrument panel of a Lancair, 
even with a $100k (!!!!!!!) panel.)

Postprocessing produced flight data (pressure 
altitude, density altitude, ROC, IAS, TAS, etc.) 
and engine data sufficient to define and remedy 
installation problems (many) quickly.

This system came into being after I found that it 
was simply impossible to record sufficient data 
with sufficient accuracy from the large panel of 
(mostly digital) instrumentation I built into the 
rear cabin of the test aircraft, with a dedicated
data-taking person at the panel. 

Lest you think this was done on some 
government-funded debacle, the total cost of the 
DAQ system was less than $9k (of which, 
a large percentage was sensors).

Jack Kane
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Please send your photos and drawings to marvkaye@olsusa.com.
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