lehpron
Posts: 6846
Joined: Tue Jul 10, 2001 3:42 am

Turbo-Superchargers

Sun Jan 20, 2002 5:23 pm

Are any aircraft still using these engines or are turboprops the all-purpose small airplane engine nowadays?
The meaning of life is curiosity; we were put on this planet to explore opportunities.
 
tom775257
Posts: 141
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RE: Turbo-Superchargers

Sun Jan 20, 2002 9:51 pm

If you are thinking in terms of aircraft used commercially for pax transportation, a Piper Seneca has twin turbo charged piston engines (used usually on private charter/ twin training). Many GA aircraft have turbocharged piston engines. p.s. you put "turbo-superchargers", you might know, but incase you don't a turbo charger is driven by a turbine which has exhaust gases passing over it. A supercharger is driven by a drive belt connected to the engine.
cheers. tom.
 
LZ-TLT
Posts: 427
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RE: Turbo-Superchargers

Sun Jan 20, 2002 11:38 pm

On the superchargers - I wonder what type they are. Are they the well-known Rootes superchargers(as used on dragsters and racing cars) or some other type, (for example a Concentrix). Also, what about the manufacturers? The ones used in the motorsport scene(drag racing, tractor pulling) usually come from Holley, Littlefield or SSI, do these manufacturers supply the aviation industry?
 
aaron atp
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Joined: Sun Mar 19, 2000 1:17 pm

Tom

Mon Jan 21, 2002 1:11 am

actually, turbochargers were originally known as turbo-superchargers... from what I know the 'super' part was dropped thirty years to shorten it to turbochargers, however, it is far from incorrect when written the original way.

By definition, a supercharger can be belt, gear, or exhaust driven, but the majority of the population differentiates between a turbocharger and supercharger. By writing turbo-supercharger one is differentiating between belt-driven supercharger AND gear-driven supercharger. Most people I know use "blower" for the latter two positive-displacement superchargers. (i.e. on a Detroit Diesel 16V92 TBA, the 'TBA' stands for "Turbo, Blown, and Aftercooled")

just a tidbit of useless knowledge from the archives...



As for the original question, low blower and high blower are relics that disappeared with the radial engine. I suppose that as far as recips go, the trend is away from turbos (in my opinion). Turbos reduce TBO and for most GA aircraft they are expensive and often un-needed. Several STC's exist that allow TSIO-550's to be retrofitted to natural aspiration.

50 years ago virtually every radial engine had a some sort of supercharger, while today, a relatively small percentage of the opposed 4/6's are turbocharged.

Speaking in percentages, I would have to disagree that the turboprop is the more popular engine for utility use since a hot section might cost you $50K, but looking at the PC12, C208, TBM700, PA-46 TP, it's undeniable that turboprops are gaining popularity very fast.



aaron
 
tom775257
Posts: 141
Joined: Fri Dec 22, 2000 1:51 pm

Aaron Atp

Mon Jan 21, 2002 6:07 am

Hi,
thanks for the info, I'm always glad to learn stuff. Sorry if what I originally said sounded condescending, while incorrect at the same time.
Thanks for the correction.
Best regards,
Tom.
 
242
Posts: 495
Joined: Tue Oct 24, 2000 1:10 pm

RE: Turbo-Superchargers

Mon Jan 21, 2002 12:49 pm

I'm curious as to how the term "turbo-supercharger" came to describe a turbo only engine. In A&P school, I was taught that a *turbo-supercharged* engine was just that-- an engine with both an exaust gas driven turbo that fed a crank driven supercharger to produce an unholy amount of boost.

 
chdmcmanus
Posts: 372
Joined: Wed Mar 21, 2001 12:53 am

RE: Turbo-Superchargers

Mon Jan 21, 2002 11:41 pm

I've got to go with 242 on this one, all of the big recips I’ve worked on were just the way he said, either Turbo, Super, or Turbo-super, each with a different drive method.

Regards,
ChD
"Never trust a clean Crew Chief"
 
aaron atp
Posts: 517
Joined: Sun Mar 19, 2000 1:17 pm

RE: Turbo-Superchargers

Tue Jan 22, 2002 3:58 pm

well, I can't agree with you guys on that one...

Just to make sure I wasn't imagining this I looked it up on page 528 of the Dictionary of Aeronautical Terms, which defines turbosupercharger as "The original name for a turbocharger" as the only definition.

and from the American Heritage Dictionary

Now arguing dictionary semantics won't help us here, but consider doing a search on your favorite search engine and look at the context that turbosupercharger is used in. In 100% of the aviation related pages I looked at, none used the context that I refer to as a turbo/blown configuration...

Here is a bit more of my background for turbo/blown configurations. Detroit Diesel engines are 2 stroke diesels which RELY on supercharging to operate. The blowers are gear driven, and each bank uses a rather large turbo. These engines have a blower bypass that allows the turbocharged air to bypass the blowers because it can supply more air without the positive displacement blowers in the way... So at high RPMS only the turbos supply the air. I am not a powerplant mechanic and I don't have any real experience with the internals of big radial so can't offer a truly definitive answer in this situation.

If this is only something that was 'described to me' I might wonder about it's validity. I can think of a few things that have been propagated by misinformed instructors in my life. Let me know what you decide if you dig into it.

document from General Electric, 1943
7.c. Turbosuperchargers
At the present time, turbosuperchargers are used in series with geared superchargers, the intercooler and carburetor being located between them. In this way, maximum use can be made of the advantages of each type.


From this, I understand why this might cause confusion, but notice that they too differentiate from geared superchargers and turbosuperchargers, but they never use the term turbocharger in the document. This says that they were used in conjuction with the geared variant, which leads me too believe that someone just grouped the two together in error at some point. It's all semantics and open to interpretation, but interesting reading nonetheless.


Also note the figure 11 "Cutaway Turbosupercharger" at section 9.a. which clearly shows only what we know as a turbocharger...

aaron
 
lehpron
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RE: Turbo-Superchargers

Tue Jan 22, 2002 4:01 pm

As I understand it from reading an aerodynamics book (sorry I didn't catch the year, looked old), a regular piston -internal combustion engine can perfom properly up to 11,000 feet, any higher and the payload must drop to compensate.

A turbo-supercharger simply has a single commpressor-fan pumping in air for the combustion engine and another turbine-fan sucking out the exhaust. This is supposed to allow higher altitude flight to 27,000 feet before having to reduce payload to maintain performance.

Again, I don't know how old the book was, so any newer info would be appreciated.

Were engines like these on the Mustang, Spitfire or other WWII-aged planes?
The meaning of life is curiosity; we were put on this planet to explore opportunities.
 
aaron atp
Posts: 517
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RE: Turbo-Superchargers

Tue Jan 22, 2002 4:08 pm

One last thing, I should say that the name was shortened over time to prevent confusion after the turbos began to be used without the gear driven blowers.

Readers should realize, however, that exhaust driven turbos are still superchargers, regardless of the final configuration. In the above reference document they also call turbosuperchargers by another name "external supercharger."


aaron
 
vc10
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Joined: Thu Nov 15, 2001 4:13 am

RE: Turbo-Superchargers

Wed Jan 23, 2002 6:28 am

242 and chd,
Just to add my bit on this subject I think you are all correct, it is just the way you use the words

A super charger is directly driven by the engine so as to boost the pressure of the intake air
A turbo charger does exactly the same but is driven by a turbine in the exhaust gas flow.
The Wright Cyclone engine [ two banks of 9 cylinders] was a supercharged engine as far as boost pressure was concerned, but during it's development they also fitted an exhaust driven turbine to it, which recovered energy from the exhaust flow and delivered it via gears and driven rods back onto the engine's cranckshaft. In fact each engine had 3 turbines, each recovering about 60 HP [ so a total of 180 HP ] at take-off power
These engines were known as Turbo compound engines and were fitted to the later Constellation, the DC-7 and many others.

Hope that helps a bit little vc10
 
LZ-TLT
Posts: 427
Joined: Mon Apr 23, 2001 10:34 am

RE: Turbo-Superchargers

Wed Jan 23, 2002 10:07 am

Just a note:

Vc10 is rigfht on the Turbo compount engines. Curtiss-Wright referred to the unit used as "Power Recovery Turbine"(PRT)
 
aaron atp
Posts: 517
Joined: Sun Mar 19, 2000 1:17 pm

RE: Turbo-Superchargers

Thu Jan 24, 2002 7:32 am

hrmm... if you argue that a turbocharger is not a supercharger you are wrong. I can't decide whether or not that's what you meant, but that's where I stand on this one.

Turbocharger: Exhaust driven, external supercharger

Turbosupercharger: the original name for a turbocharger OR a turbocharger that compliments an internal supercharger (this delination is necessary because turbosuperchargers were initally designed to be used on gear driven supercharged engines. It was many years after they went to turbosuperchargers _only_ that 'super' was dropped from the middle)

Supercharger: belt, gear, or exhaust driven pump or blower which compresses intake air (internal/external)


If you disagree with me, write a letter to Teledyne Continental and ask them why they use "TS" for TurboSupercharged on their engine models, i.e. TSIO-520-R, even though they do not use internal superchargers.

I do understand that common usage differentiates between turbocharger and supercharger, but common usage doesn't mean "correct usage." In normal discussions I wouldn't bring up the difference, but the first reply made this necessary; In fact, I subscribe to this common usage although I know it isn't fully correct.

FAA AC 65-12A "Powerplant Handbook" agrees with me, and says that an externally-driven supercharger is a turbosupercharger, which is "usually" called a turbocharger on light aircraft. [page 84 in my copy]


I don't want to piss anyone off or sound arrogant here, but it's something to think about...




aaron
 
411A
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RE: Turbo-Superchargers

Thu Jan 24, 2002 4:19 pm

Power recovery turbines (PRT) used on the R3350-EA4 used a fluid coupling to the engine crankshaft to deliver extra housepower...on takeoff an extra 650 shp, and all this from 18 cylinders..quite an achievement.
These PRT's tended to overheat in high blower and had a service life of approximately 200 hours. Operation in low blower extended life considerably.
All in all, a good idea...but overshadowed by the jet age.
The Lockheed 1649A used the -EA4 engine for VERY long range operations, up to 21 hours. They would run out of oil before running out of fuel.
Ah Lockheed...

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