Air pump to aero motor conversion

I have noticed alot of modern air-compressor pumps use a 'V twin' arrangement reminiscent of aero-engines on wooden homebuilt fixed wing aircraft in their glory days, the 1930s.

Would it be possible, and what would it take to convert one of these things into an aero-engine? (has it been perhaps even been tried already).

I saw one lying about on my local queyside, and it seemed amazingly lightweight!

http://www.machinemart.co.uk/shop/p...ump/path/air-compressor-pumps-pumpmotor-units

The one above is made of cast iron, but there are aluminium ones which are alot lighter.



Dave

No chance mate..
I could write 50 pages as to why not, but trust me, it can't be done without enough modifications to warrant buying a dozen new 912a Rotax motors.

I agree with Tex, Not enough bandwidth here to explain, you be better off to start from scratch, and scratch I mean start with smelting your own ore..........

While not an air compressor, and to give you some hope in your search, there is a company in the midwest (Missouri?) that has taken a V-Twin generator (Generac I believe) and uses it to power an ultralight airplane, getting some 35 horses for it. They sell this conversion.

But, that is too little an amount of hp to power a draggy rotor system through the air.

Dave

Kind of an "opposite" story I know of is that an Italian V-twin motorcycle engine was used for the block , pistons and crank in some shop air compressors.

The factory sales of motorcycles had dried up and they were looking for new sources of revenue.

Now if you could find one of those original bike engines you would have just what you were looking for.

Motorcycle engines have never worked out too great for aviation , but I recall somewhere on this forum a builder was putting a Harley Engine in a Gyro.

Not sure if it flew , but it sure would have sounded great ....

Arnie

Cheers all but esp. to Kevin and Arnie.
It would be helpful to know 'in short' why not. Is there a problem with the crankcase or the crankshaft (If it isn't durable enough, why not?) which looks to all intents and purposes outwardly at least perfectly suitable.
My guess would be that the cylinders and pistons are very likely unsuitable for the prolonged higher operating temperatures, but they can through ingenuity be replaced by the aforesaid I.C variety.
I guess the process would involve for the most part alot of problems of this ilk to overcome.



Dave

Besides having to totaly redesign and replace the crank case, crankshaft,
pistons, rods, cylinders, and totaly design a valve train, cylinderheads, ignition, intake and exhaust system, should't be anything to it.

Basicaly it is an air pump, it is not designed to contain an explosion like an internal combustion engine, I say go for it, you'll learn alot.

Sorry Scott.

You don't state why a new crankcase & contents is required.

I was talking mainly about interchanging the 'top end' (cylinders/pistons) for existing IC parts.

To merge a V twin IC with a V twin air pump in effect.

Dave

St Just?

St Just?

Curious, Dave, where is St Just? British by any chance?, or one of the Br. colonies?

Air compressor use splash oiling, an engine like you are talking requires a presurized lubrication system.
Plus the stresses on the case and crank are much much more severe in an internal combustion engine.
This is like asking if "I can turbo charge my car with my wifes hairdryer"
It ain't the same thing it aint gonna work.
I have worked on HUGE Gardner-Denver compressors, as well as engines,
If you have lots of time and lots of money go for it.
Otherwise learn as much as you can about engines, and it will all make sense when you understand the priciples and operations.

Dave,

Just to start you would have to not just redesign, but design a head for the cylinders.. one with valves and lifters and now you have ignition and timing issues.
Ok, $50,000 in research later you now have a working head with valves, lifters, iginition system, etc...
The cylinders are designed for removing heat of compression at 700 RPM and a delta T of 75º Celcius. Now you are running the cylinders at 3000 RPM and a delta T of 300º Celcius and the materials aren't designed to dissipate those kiloWatts of energy. You end up with a seized cylinders and pistons.. OK now $75,000 later you've researched and designed the perfect cylinder with just the right wall thickness and just the right fin layout as not to cause cylinder fatigue and cracking..
Now we realize that our oiling system is a splash ring type and designed for a 15hp input drive and not a 65hp output. $100,000 dollars later we've perfected the oiling system complete with pump and sump and properly ported crankshaft, conrods, knuckles... we're sweet now and almost home.. BUT we realized that we've REVERSED the stress on our engine and it's no longer from the crank to the pistons, it's from the pistons to the crank and our bearings are not up to snuff, but we can't make it up to snuff without remanufacturing the crank case to beef up the blocks. So we spend another $25,000 to design a new crankcase to hold our newly designed bearing blocks and our newly designed oil seals....

WAIT....

What part of our air compressor motor is still original?? None of it..
What do we now have? An aviation motor that's designed around an AIR COMPRESSOR.
So while you are building your air compressor turned engine, I'll take my $ down to Gyro-Motorz-R-Us and grab up a nice lil 582 for a song and a dance

Scott!! You mean I can't turbo-up my gyro with the Mrs's new hair-dryer??!!! But it says TURBO right on the side!! :rant::twitch::rant:

I do hear what you say above.
Temperature & lubrication.
Valve train, and ignition (magneto).
I wouldn't or wasn't thinking of the very costly 'design from scratch' route but was actually curious if I could merge the top end of an existing V twin IC (including pistons; making a camshaft aint rocket science) with the bottom of the compressor.
Suitably cooled cylinder liners and smaller pistons, is another option.

Vibration and shock cooling may require testing the prototype to destruction, on a testbed.

Do you think the Wright brothers would have flown if they hadn't perservered each time they had a fault?

I'm sure you have a very good point, presumably resultant of you own experiences of such endeavours.

Dave

Hi Kevin.
St Just is on the SW peninsula of mainland Britain.
Dave

I am sure that you could make something run out of scrap yard parts, but how long would it last? And how eficient would it be?

The wright brothers engine was what, 180 lbs and produced 12 HP.
No doubt a technological marvel for that time.

Well it would therefore pay to test the first version to destruction.

Here's a way to convert just one cylinder to IC.

Dave

http://thekneeslider.com/archives/2009/01/12/ducati-v-one-twin-to-supercharged-single-conversion/

It would make an interesting science project, but i do not think I would trust it on an aircraft. especially since there are plenty of good options out there.

Making a pump from an engine is easy, everything is already overbuilt, you just have to change a few things and remove others.
but making a pump into an engine is much harder.
Ingersol Rand as well as others, have aircompressors made from V-8 fords, they change one bank of cyl heads with a compressor head, so one side of the engine is a compressor and the other side is the engine.

scottessex said:

It would make an interesting science project, but i do not think I would trust it on an aircraft. especially since there are plenty of good options out there.

Making a pump from an engine is easy, everything is already overbuilt, you just have to change a few things and remove others.
but making a pump into an engine is much harder.
Ingersol Rand as well as others, have aircompressors made from V-8 fords, they change one bank of cyl heads with a compressor head, so one side of the engine is a compressor and the other side is the engine.

Click to expand...

Wait, Scott, wait!
Eureka!
How 'bout the aformentioned V8 engine pumping an air compressor BACKWARDS, driving a prop? A bit heavy but dang!, an air compressor spinning a prop. Voila! :hail:
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Dave, Cracker..
Many of the commercial air compressors are standard motors that have 2 of the 8 cylinders converted to pump air instead of being integral to the motor. It works great sorta.. Just keep in mind the limitations to this type of compressor.
Firstly, they are positive displacement pumps so while the pressures can become quite high, the volume is limited to the volume of the cylinders X the RPM to get your CFM.
While in theory this may sound great, in practice it doesn't provide adequate volume for applications like driving a prop or rotor. Second... The air is "pulsed" and will wreak havoc on mechanical parts until buffered with a tank of adequate size. So let's just say you are using 1500 CFM of air you will need a tank that will handle that amount of air compressed to it's final pressure X 10 to buffer. So lets gamble on a 150 CF tank @ 100 psi? Now you have a flying air compressor.. literally... and everyone will want to borrow it next time they shingle their house.
a centrifugal pump or screw type pump would operate less efficiently but provide a better output of air quality for driving a prop... Nothing will beat the efficiency of just hooking it straight up to the motor though mechanical means.

I know this is off topic and hardly relates to turning an air compressor into a motor.

I was just kiddin'..........
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cracker said:

I was just kiddin'..........
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Click to expand...

No you weren't... Now go put the engine back in the wife's car....