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Gentlemen:
As some of you know, I hired George Braly and his team at GAMI to try and determine what if anything could be done to improve the cooling efficiencies of the TSIO 550 engine installation in the Lancair IV-P. As many of you have experienced, the 550 engine has a tendency to run hot especially in the climb and in the high altitude cruise phases of flight.
In my case even with the "Dolly Parton" cowl, the aircraft had to be operated at minimum airspeed of 165 KIAS during climb in order to keep the CHT's below 400 degrees with a maximum of 75% power during climb and in the flight levels, power settings of 65-70% of power or less were required in order to keep the temps under control.
After attending the Advanced Pilots Seminar at GAMI in January and listening to them preach the importance of good baffling design to engine performance, I issued George a challenge:
I said George if you’re right and all it takes is a fundamental understanding of what’s going on under the cowl and the ability to tweak the baffling system, monitor it with a video camera under the cowl watching the air flow by attaching pieces of string to the cylinders etc ect, and if you’re so sure it will work why haven’t you fixed the problem.
He said he didn’t have a Lancair to play with so … I solved that problem and gave him mine…and a blank check to play with too.
After several weeks of R&D, flight tests, and in excess of 10 custom fabricated components attached in strategic places throughout the engine compartment to supplement the existing baffle design, the GAMI Lancair Baffling system was born. Here are the results summarized:
BEFORE MODIFICATION (flight test 1-20-03):
Altitude Hottest CHT MP KIAS KTAS GPH
17,500 358 31.6 185 246 18.4
Climb 395 31.5 165 Climb 1200 FPM
AFTER MODIFICATIONS (flight test 3-7-03):
Altitude Hottest CHT MP KIAS KTAS GPH
17,500 349 32.6 193 254 18.6
Climb 376 36.5 145 Climb 2200 FPM
IMPORTANT CONSIDERATIONS:
The important point is that they have increased the cruise speed of the Lancair by 8 KTAS with virtually the identical fuel flow (18.6 vs 18.4) this was done by carrying an extra inch of MP (32.6 vs 31.6). The ability to carry extra MP with LOWER temps (349 vs 358) will easily enable us all to carry more MP at higher altitudes and hence receive those extra 8 KTAS for every additional inch of MP.
SAMPLE REAL WORLD FLIGHT DATA (March 30, 2003)
As an example of this baffling system in action, today I landed at Apple Valley Airport (APV) and after having breakfast fired up the plane and checked the OAT which was 79 degrees F. Since APV is in a remote area I called Approach from the ground and received a clearance to take off and climb un-restricted to FL 250.
I timed the climb from wheels up on take off (airport elevation is 3000 MSL) to FL 250 at 11 min 14 sec. This yields an average rate of climb of 2044 FPM. During the climb the hottest CHT recorded was 378 degrees carrying a full 36.5 MP, 2650 RPM
Then I leveled off and set high speed cruise of 32.8 in MP, 2500 RPM and leaned to 18.9 GPH which gives me roughly 80% power. I was showing the hottest CHT at 352 degrees, 187 KIAS, 271 KTAS according to the EFIS.
CONCLUSION:
I am a believer. George and his gang of engineers have really done it. For the first time I have a Lancair which can be operated at the best part of its performance envelope without risking damage from over temping.
George has told me that he will be making these modifications available to everyone in the form of customized baffling mods for each individual plane. The cost…I am not sure but understand it will be under $10,000. If you think about it, the ability to gain 15% more HP in cruise with temps which are reduced to lower than they are at economy power, this is a real bargain.
With the TSIO 550 costing over $70,000 the ability to harness and actually USE an additional 15% of the available horsepower in cruise is a better value for the money than the engine was when you bought it (i.e. $700/ percent of HP from TCM verses $666/percent of HP via the GAMI modification).
All in all I am one happy customer. For the record, I don’t have a stake in this modification, I do not get paid a royalty or commission, I don’t own any stock, all I get from this venture is the satisfaction of knowing my plane and my money helped develop a system which will make all of our plans faster and safer.
So call George and he has all the details on spreadsheets and graphs which he downloaded from the EFIS during flight tests. I am sure he can explain in much more detail how this all works and what is involved.
I hope this modification works as well for you as it has for me and with it we can all fly faster, farther and stay cooler!
Regards,
Dave Riggs
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