Anyone tried to start an air start turbine with regular shop compressor pressures? possible modifications? seems like a good idea

I have started turbines many times on a small shop compressor. The reason a scuba bottle is used for the most part is the transportability , secondly it offers more starts than a regular portable air tank due to the higher pressures it has more cubic ft of air. I.E. a ten gallon protable air tank holds 100PSI, (figures are exagerated) say that might be 10 cubic ft of air packed into a ten gallon tank as opposed to maybe 30 cubic ft of air packed into a 2 gallon space at 1500 psi. again the figures are exagerated there are formulas for figuring out the correct numbers I just tried to make it easier to understand. Now if you had a good sorce of electric at the field a portable air compressor will start a tubine till you wear out but how many meets or fiels come to mind where there is reliable electric service. I have gotten 3 to 4 good starts off of a portable air tank. I am not sure of the number with a scuba tank, I am sure sombody else could provide that info.


Jim

Cool, Thats what I wanted to know. I just thought that maybe the internal diameter of the air system might be too small to use less pressure. I carry an electric compressor with my fiel equip anyway, so then all I'd need is to bring my air tank.

Just thought that it would get old having to go to the dive shop to get the scuba filled.

Thanks,

Rick

That is what SWB is recommending for their new Mamba. Use an air tank for pumping up tires and the compressor for your retracts!

Guys,

Four years ago After I bought my first turbine, an AMT Mercury, I figured out it would be a bit of trouble to fill and lug aroung scuba bottles. I dug around and found a small commercial duty 12 volt DC air compressor and put together a prototype assembly with a storage tank for start air and a pressure switch which would cut off at 125 psi, and re-engage at 80 psi. I took the setup to the airport on my next flying session and successfully started the Mercury and the AMT Pegasus turbines with no problem whatsoever. I used a 3 gal. tank, and it was plenty of air for start and cool down. Recovery was very rapid. I then built a huge wooden box to hold a deep cycle marine battery, air tank, air compressor, 5 gal. fuel tank, propane, any kind of spares I could think of, kitchen sink, etc. I bought casters for it because by the time I stuffed it with all the goodies, it weighed about 80 lbs. I also intended to build an airplane cradle on top of it. Well, I work so slowly that by the time I got around to rigging it, I had coverted to auto start and didn't need it anymore. I am attaching a photo of the compressor for those of you who are interested. A friend ordered mine for me, so I don't know where it came from. David Reid ordered one similar to it, so he could tell you where to get one.

Dennis Lott

Okay, here it is.

This compressor is made by Thomas Compressors.

Dennis

AMT has this really neat little start cart now with a pump and tank for starting their engines. Saw it at Toledo, wish I had taken a picture and asked the price. The SWB folks said they were coming up with something similar for the Mamba. I really don't care much for 3000 psi scuba tanks, too dangerous. AMT's are fantastic, utterly bulletproof engines but I didn't buy one because I just couldn't stand that whole scuba tank leaf blower routine. I can see the benefits of airstart, but wound up going with JetCat for reliability and "no fuss, no muss" starting. I like the direction AMT is going and can't wait to see what SWB comes up with for the Mamba. Sounds like you guys are already blazing this trail.

Dennis, what size deep cycle battery (what capacity) and how many fill/drain cycles could you get with it?

Mine is similar to Dennis' and also was made by Thomas Industries. I had to special order it as mine has a little higher duty cycle (usage time) mine will aslo pump up to 175 PSI but you need to be aware that your storage tank may not be rated that high. I also bought a SquareD pressure switch that operates on a differentil between high and low pressure which you can select. I used a 5 gallon portable air tank and used it to start the RAM's a couple of times. I build faster than Dennis but I never did get around to assembling it all together into a usable unit. The compressor was fairly expensive, somewhere around $250-300. I used a deep cycle marine battery that I keep in my trailer anyway, and mine was going to be mounted on a wagon.

But......... I got lazy and converted everything to autostart as well now all I have to carry is my fuel, air compressor (for retracts) start gas, and fire extinguisher. Did I mention how well the JetCat autostart works???


David Reid

I don't know for sure. It was one we had for jet trips, probably 600 CCA. I never used it enough to know how long it would last. The air compressor recovered so quickly, it should easily last all weekend, maybe more.

David, yes the JetCat auto start is superb! I haven't even used the blower for cool down since going with JetCat.

Dennis

BTW, the first part of the last post was directed to Wocketman's question about the battery size.

Dennis

Hey Woketman. If you decide to go with the compressor setup, let me know. I might consider selling mine. It has no run time. I used my friend's compressor for the trials.

Dennis

There's no might to it......if anyone wants my setup it is for sale! I don't need it anymore.


David Reid

Why do you not use a 550 size electric motor for starting??
Regards
Tomas

David and David:

Sounds like you guys subscribe to the Ray Davis school of turbine support equipment. The first time I saw his setup I thought he had brought a dresser to the field. It took both he and his helper Bob to lift it out of his minivan. His big Avonds F15 sits atop the rig. Here is a pic of at least a portion of his "start cart:"
http://www.usamt.com/gallery_ray_davis.html

By the way, if you want to take a gander at something amusing, check out AMT Usa's site at the "Eliminator." It's a portable air compressor for starting turbines. You too can own this wonderful device for the mere sum of $650! Hmmm, I think a scuba/pony tank combo might still be preferable -- or of course we could all take the electric motor approach like some of you guys.

Antony

Antony,

Where I live the closest scuba shop is an hour away. You have to take your tank there and leave it over night. THey transport it to a different location to fill it at night then you come back the next day. Terribly inconvinient! But......autostart is great, no muss, no fuss, hit the go button and go fly. BTW the compressor alone is around 250-300 so AMT's rig is not really out of line considering he needs to make a profit to make it worth his while.

It's funny David, I have lived near water all my life and so had access to scuba shops. I didn't give much thought to what folks in the interior or southwest of our country do if they need scuba tanks serviced. Electric motor or compressor starting really make sense given such locations.

I suppose you're right about AMT needing to mark the Eliminator up in order to turn a profit. It still seems a bit pricey for a piece of support equipment.

Antony

a 30 dollar air pump??

It looks like it is only being marketed as a way to fill your brakes and retracts!!

obviously it is meant to start turbines, whay don't they say that on the web page?

Matt, what are you talking about? Where did you see the "30 dollar" pump? What web page? Thanks.

Mark:

Matt was asking and answering the question "what is AMT USA's eliminator eliminating -- a $30 air pump." AMT is billing the eliminator as eliminating more than the scuba tank, but also the retract and brake air pump or comressor. I think Matt was agreeing that $650 is a bit steep to replace those three items. Lessee, I spent about $200 on all of these put together (tank, reg, hose, gauge, mini compressor).

The description of what the eliminator does is on the "optional equipment" page.

In answer to Matt's question, I guess they assumed it was obvious it is used to start turbines. It's not exactly evident from the description though.

Antony

OK, I understand. Thanks Antony.