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01-06-2008, 12:10 PM
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Join Date: Feb 2007
Location: Durango, CO
Posts: 126
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In 1974 I checked out in the F-15A and flew it for five years before retiring. It had 50,000 pounds of thrust and only weighed 39,000 pounds at takeoff. At that time it held all eight time-to-climb records and some may even stand today. Think of this: 9,843' in 27.57 seconds, 19,685' in 39.33 seconds, 29,528' in 48.86 seconds, 39,370' in 59.38 seconds, 49,212' in 77.04 seconds, 65,617' in 122.94 seconds, 82.021' in 161.02 seconds and 98,425' in 207.8 seconds. With a 600 gallon centerline tank the bird would climb to 42,000' in twelve minutes and only be 40 miles from the field and do it with military power only (no afterburner). I very often cruised at 50,000' on cross countries at .98 Mach. That is about 10 miles/minute. I don't go quite as fast now, but I want you to know that the RV you are flying right now has the light, responsive feel of a fighter and you built the aircraft! If you are still pounding rivets keep at it. These RVs are sweet, even if they don't have a jet engine!
Jim
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01-06-2008, 02:56 PM
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Join Date: Jan 2005
Location: Ottawa, Canada
Posts: 2,357
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Quote:
Originally Posted by JAT
In 1974 I checked out in the F-15A and flew it for five years before retiring. It had 50,000 pounds of thrust and only weighed 39,000 pounds at takeoff. At that time it held all eight time-to-climb records and some may even stand today. Think of this: 9,843' in 27.57 seconds, 19,685' in 39.33 seconds, 29,528' in 48.86 seconds, 39,370' in 59.38 seconds, 49,212' in 77.04 seconds, 65,617' in 122.94 seconds, 82.021' in 161.02 seconds and 98,425' in 207.8 seconds
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Most of those records were later taken by Soviet aircraft, but the one for 20,000 m (65,616 ft) is still held by the F-15. The records up to 15,000 m (49,213 ft) are held by one of the prototype Su-27s, and the records from 25,000 m (82,021 ft) to 35,000 m (114,829 ft) are held by prototype MiG-25s.
The lower altitude time to climb records are even more impressive if you consider that the clock starts during the take-off roll when the aircraft first moves down the runway. The current record for 3,000 m (9,843 ft) is 25.37 seconds.
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01-07-2008, 06:22 AM
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Join Date: Jan 2005
Location: Louisville, Ga
Posts: 7,840
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Too old for risks.
Quote:
Originally Posted by Paul Eastham
Hey Pierre, here's a dumb question then -- why are you running a turbine in your Air Tractor then? Your average altitude is probably 100' AGL for the life of the aircraft. Need the extra power, maybe?Paul
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Hope you're doing well!
Hi Paul,
The old 1340 cu. in. Pratts are so old and crack cylinders so often that it's become less expensive in the long run to run a PT-6. My old 1340 powered Air Tractor wouldn't hardly go 1000 hours without needing a $25,000 overhaul. My PT-6 has over 8000 hours and hasn't had an overhaul, just the CT wheel (compressor turbine) replaced...that and $1500 hot section inspections at 1000-1200 hours. I would have already spent $200,000 on overhauls on a 1340 in the same time frame. I also use 1 quart of Exxon 2380 synthetic every 30 hours ($9.00) compared to 2 gallons a day of Aeroshell 120 (60W) at $80 a day in the 1340. I sat down and did some serious math and the big winner, all things considered, the PT-6 won hands down.
I also had to park the old Air Tractor in a cornfield when the master-rod cylinder started shucking the lower cylinder skirt and the pieces internally beating the $$it out of the other reciprocating pieces....I'm too old for that
FWIW, the PT-6 is one of the few engines I don't mind riding behind at night!
Regards,
__________________
Pierre Smith
RV-10, 510 TT
RV6A (Sojourner) 180 HP, Catto 3 Bl (502Hrs), gone...and already missed
Air Tractor AT 502B PT 6-15 Sold
Air Tractor 402 PT-6-20 Sold
EAA Flight Advisor/CFI/Tech Counselor
Louisville, Ga
It's never skill or craftsmanship that completes airplanes, it's the will to do so,
Patrick Kenny, EAA 275132
Dues gladly paid!
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01-07-2008, 06:43 AM
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VAF Moderator / Line Boy
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Join Date: Jan 2005
Location: Dayton, NV
Posts: 12,256
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Quote:
Originally Posted by pierre smith
FWIW, the PT-6 is one of the few engines I don't mind riding behind at night!
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That night crop-dusting has got to be a blast!!  
__________________
Paul F. Dye
Editor at Large - KITPLANES Magazine
RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
A&P, EAA Tech Counselor/Flight Advisor
Dayton Valley Airpark (A34)
http://Ironflight.com
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01-07-2008, 06:56 AM
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Join Date: Jan 2005
Location: Louisville, Ga
Posts: 7,840
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No night ag..
......for me, Paul.......too many powerlines. California and Az are big on night ag, mainly because of high daytime temps and the associated chemical drift/evaporation problems during daytime ops. I do, however have a night-equipped Air Tractor...over 1 million candlepower with huge retractable lights...BTW, when one doesn't retract, it yaws the airplane 'cause it's out near the tip on a 50' wingspan.
Regards,
__________________
Pierre Smith
RV-10, 510 TT
RV6A (Sojourner) 180 HP, Catto 3 Bl (502Hrs), gone...and already missed
Air Tractor AT 502B PT 6-15 Sold
Air Tractor 402 PT-6-20 Sold
EAA Flight Advisor/CFI/Tech Counselor
Louisville, Ga
It's never skill or craftsmanship that completes airplanes, it's the will to do so,
Patrick Kenny, EAA 275132
Dues gladly paid!
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01-08-2008, 01:02 PM
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Join Date: Oct 2007
Location: Aptos, CA (previously Reno, 21 years!)
Posts: 247
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Hi Pierre, I share your sentiments about the PT-6
The PT-6 engine was originally designed to run oil field pumps in Texas and Oklahoma, unsupervised, for days on end with no maintenance.
The best thing that ever happened to turboprop airplanes was the introduction of this "pump" to an engine mount. I've got many an hour with my life in the balance based on how well that engine performed. In over 4000 hours of PT-6 time I've got (8000 if you count 4000 with two engines)... I've never, ever had so much as a hint of quitting from that engine. I did see a very brief compressor stall one time, a momentary "BANG" in heavy ice (with ice protection in used BTW) followed by no more hint of complaints. I think she was just clearing her throat 
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01-08-2008, 03:27 PM
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Join Date: Jan 2005
Location: Ottawa, Canada
Posts: 2,357
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Quote:
Originally Posted by Eddie P
The PT-6 engine was originally designed to run oil field pumps in Texas and Oklahoma, unsupervised, for days on end with no maintenance.
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I'd love to see a reference for that "fact". All the info I have ever read says that the PT-6 was designed for aircraft turbo-prop applications first, and that other applications came later.
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01-08-2008, 03:39 PM
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Join Date: May 2006
Location: Louisville, KY
Posts: 94
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3 shutdowns in 5000 hours with PT-6. But they were in BE-1900s that were used pretty hard. Still, enough reserve power in the good motor to make RTB a non event. Great motor. Would love to fly Pierres' ag plane when it's empty... ;-)
__________________
Dennis
RV-4, bought flying
RV-3B preview plans
HR 2 ???
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01-08-2008, 08:51 PM
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Join Date: Oct 2007
Location: Aptos, CA (previously Reno, 21 years!)
Posts: 247
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Quote:
Originally Posted by Kevin Horton
I'd love to see a reference for that "fact". All the info I have ever read says that the PT-6 was designed for aircraft turbo-prop applications first, and that other applications came later.
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I never really gave much pause for thought to the well told Oil Rig story that a Beech Engineer told me several years ago concerning the PT-6 engine. The same story was also told to me by another guy a few years later - stuff gets around in folk lore I suppose.
But I wouldn't be much of a pilot if I didn't share in the skepticism when a fellow pilot raises the BS flag! The internet is an amazing place to research, but some of what you find can be an equally loaded mess. I did find a very good source on the PT-6 engine in the form of a published aviation history book though:
http://books.google.com/books?id=V0S...ay-w#PPA433,M1
Check out chapter 8 starting on page 443 - they later get into the talking about the DS-10, the fore runner to the PT-6, and then the PT-6 itself. I have not found any reference to an oil rig pump, but who knows. I'll consider the story as a likely folk lore "busted" myth unless I see otherwise now!
As far as the Wikki reference on the PT-6 engine, well, it's not quite all there, but close.
Last edited by Eddie P : 01-08-2008 at 08:55 PM.
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