Pressurization - Piston Engine

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westrujp

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Joel W
How are piston aircraft (like the Aerostar) pressurized? I get pressurization from turbine engines (bleed air, etc). Is there a separate engine driven accessory pump?

Thanks in advance, I didn't spend much time on the research for this one.
 
Don't know anything about aerostars but typically the pressurization on pistons comes from the turbocharger(s).

There are some older stranger designs.
 
The two I have seen either use bleed from the turbocharger compressor which is the most common, and I worked on a Twin Commander that used a hydraulic pump to run the blower.
 
Thanks everyone. I was getting hung up on turbine outlet temperature, but I guess it shouldn't matter in practice. Pressurization should take a small volume of air, especially when combine with ram air.

Edit: that's what the HX is for in the ram air duct...
 
westrujp said:
Thanks everyone. I was getting hung up on turbine outlet temperature, but I guess it shouldn't matter in practice. Pressurization should take a small volume of air, especially when combine with ram air.

Edit: that's what the HX is for in the ram air duct...
Click to expand...

All pressurization systems have some sort of heat exchanger. Compressing air increases its temperature.
 
The old recip. airliners like the DC-4,5,6, and the super connie were pressurized by a Roots blower, on #2 or #3 and air-conditioning was provided thru a air cycle machine, called a Bootstrap blower.
 
westrujp said:
Thanks everyone. I was getting hung up on turbine outlet temperature, but I guess it shouldn't matter in practice. Pressurization should take a small volume of air, especially when combine with ram air.

Edit: that's what the HX is for in the ram air duct...
Click to expand...

some aircraft with out a turbine, simply use the discharge side of the vac pump.
 
How much does driving pressurization put more of a strain on a piston engine like in a Matrix? Has it been problematic?
 
I'd be really curious what CFM and pressure is needed to supply say, an MU-2 to max diff. You should be able to do a comparison and get some idea of the HP required to do so.
 
The leak rate of a 510 (small pressure vessel) cannot be more than 67 CFM at 8.2 PSI.
 
Anthony said:
How much does driving pressurization put more of a strain on a piston engine like in a Matrix? Has it been problematic?
Click to expand...

The Matrix is not pressurized.

Pressurization does tax a piston engine for sure.
 
Yes, there are pressurized piston versions of the Malibu and Mirage (PA46).
 
A turbine HVLP paint gun runs around 40 CFM at those pressures.
 
http://www.american-turbine.com/4000S.htm

AT4000

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[FONT=Arial,Helvetica][SIZE=+1]46.3 CFM at 3/4" restriction. 7.0 PSI measured at the air cap using 25' turbine air hose.[/SIZE][/FONT] [FONT=Arial,Helvetica][SIZE=+1]Outstanding performance with most finishes.[/SIZE][/FONT]
 
Henning said:
The Malibu, the Matrix is without the pressure vessel.
Click to expand...

Matrix is not pressurized but afaik still has the sonic nozzles and just dumps it overboard vs into a cabin. So afaik the engine still takes the same pressurization load because they were too lazy to deal with the certification issues of changing the engine.
 
Tom-D said:
The old recip. airliners like the DC-4,5,6, and the super connie were pressurized by a Roots blower, on #2 or #3 and air-conditioning was provided thru a air cycle machine, called a Bootstrap blower.
Click to expand...

The story of how Garrett pretty much invented the pressurization and air cycle environmental control systems for big piston airliners is interesting.

You can buy a corporate history of Garrett for five bucks, it's a retrospective of the company's first fifty years. The number of inventions and improvements made for the aviation and aerospace industries by Garrett is incredible. I really enjoyed the book, especially the photographs.

http://www.amazon.com/Out-thin-air-Garretts-first/dp/0961702907

Some photos and schematics of the early A/C systems in airliners:

http://www.hevac-heritage.org/electronic_books/transport/3-aircraft-AC-1950s.pdf

Garrett also invented the foil bearing, a huge advance:

https://en.wikipedia.org/wiki/Foil_bearing

And of course the TPE331, which at one time had sold more units than any other turbine engine made.
 
Kelvin said:
The Matrix is not pressurized.

Pressurization does tax a piston engine for sure.
Click to expand...

How? The turbos are working harder yes but the engine doesn't know any different.
 
narchee said:
How? The turbos are working harder yes but the engine doesn't know any different.
Click to expand...

Because the more air the turbo pumps, the more back pressure in the exhaust flow and the hotter the exhaust valves get. That's why with a turbo normalized engine you add 2" of MP to make the same power.
 
Tom-D said:
The old recip. airliners like the DC-4,5,6, and the super connie were pressurized by a Roots blower, on #2 or #3 and air-conditioning was provided thru a air cycle machine, called a Bootstrap blower.
Click to expand...


The King Air 90, A90 and B90, were also pressurized by a Roots supercharger.:yes:
 
Henning said:
Because the more air the turbo pumps, the more back pressure in the exhaust flow and the hotter the exhaust valves get. That's why with a turbo normalized engine you add 2" of MP to make the same power.
Click to expand...

I've flown turbos with and without pressurization. I haven't noticed a big difference in TITs or CHTs between the two at the same power settings and altitude. What is a FAR bigger effect is the altitude on the engine. More difficult to keep the engine cool as you get into that thin air at altitude. You're more likely to be flying higher with a pressurized plane so there is that. I suspect the effect from the higher altitude dominates any additional effect from the turbos producing about 20% more than is needed to feed the engine. Careful design of the intercoolers can easily make up for that. The turbos, though, are going to be working a lot harder.
 
kgruber said:
The King Air 90, A90 and B90, were also pressurized by a Roots supercharger.:yes:
Click to expand...
driven by a hydraulic motor, powered by a hydraulic pump on an engine

the heated air is then cooled by an air conditioner with the AC compressor driven by a belt run by an electrical motor

and to top off the rube goldberg, if you need additional heat there is a janitrol heater

the early king air's are a disaster. I tinker at least 1 hour for every hour it flies. This one is registered as a "C" but the only part from the "C" seems to be the data plate.
 
Henning said:
Because the more air the turbo pumps, the more back pressure in the exhaust flow and the hotter the exhaust valves get. That's why with a turbo normalized engine you add 2" of MP to make the same power.
Click to expand...

Can they eliminate the muffler on a turbocharged engine to lower the backpressure?
 
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