Air Supply for Field Testing

[hinote]

Here's a neat solution for starting pulsejets where you can't access conventional power or air from your shop; when I go to my test site at Avenal, CA--I don't have any access to the luxuries in my shop.

I've been using a leaf-blower for starting my pulsejets. This has met with variable success; it works quite well with the larger engines (4-inch CC diameter, and larger)--but it's not very good for anything smaller. In particular, my first start attempt with the M15E "simple-build" engine (3-inch CC diameter) was quite simple, using shop air and a "blow gun"; however, the motor started, but required a lot more finesse in the field, when I could only use the leaf blower.

So I looked around a little--and cobbled-up the rig shown in the photo. It consists of a battery-powered air compressor, feeding a compressed-air storage tank. The fitting on the air hose from the compressor has a nice threaded brass fitting that screws down tight on the tank. The power cable as well as the air lines are plenty long enough to attach the power to your car battery, and still work well behind the vehicle (I keep the thrust stand/trailer hitched to my pickup, so I need to have 15-20 feet of line from the battery under the hood, to the side of the thrust stand).

This isn't a toy--the peak power usage is 30 amps--so the motor on the compressor is quite powerful. It filled that tank from zero in less than 5 minutes.

I rigged up a quick line and adapter, to connect a blow-gun; this will make a great rig for starting pulsejets!!

Bill H.
Acoustic Propulsion Concepts

".......some day soon we'll be flying airplanes powered by pulsejets."

[Dang911]

This works great for me, and starts up my really small engines.....

[hinote]

In particular, my first start attempt with the M15E "simple-build" engine (3-inch CC diameter) was quite simple, using shop air and a "blow gun";

The real kicker for me was the other night--when I was able to start the engine with the inset intake. This was at the edge of the garage--and I had access to compressed air from my shop.

Also, I'm going to start playing with a permanent start-air line, set into the intake. SNECMA did this on the Escopette installation on the gliders (and probably others too). I think it's a neat way to get a consistent start. Looks professional, too--when the public is watching a demo.

BTW all you propane guys--don't forget the possibility of using a "start-stinger". This eliminates all the hassle with separate air sources.

It uses the energy stored (as pressure) in the propane tank. When properly done, the "stinger" creates a high velocity jet of propane that induces fresh-air flow along with it. It works especially well if you have a well-sorted (easy starting) engine. I demo'ed this concept at the PJ meet last year with my "mini-Escopeta". Just slam the stinger valve open and combustion is initiated; after a suitable warmup period, turn the primary fueling system on slowly and the engine will transition into full resonance.

Bill H.
Acoustic Propulsion Concepts

".......some day soon we'll be flying airplanes powered by pulsejets."

[hinote]

This works great for me, and starts up my really small engines.....

I thought about getting one of those. Sharper Image has a really cool dainty little one--similar to yours. Stuff like that is for the rich guys, though.

My rig will offer me more flexibility in my field work. I'm pleased with the setup so far.

Bill H.
Acoustic Propulsion Concepts

".......some day soon we'll be flying airplanes powered by pulsejets."

[Eric]

Power inverters seem to be coming down in price too, could probably pick up one and run a little 112 v lab in the back of your truck.

How long of battery life do you get out of that neat little blower?

Eric

[Mark]

http://www.pricegrabber.com/search_getp ... eaf+blower

[hinote]

Power inverters seem to be coming down in price too, could probably pick up one and run a little 112 v lab in the back of your truck.

http://www.harborfreight.com/cpi/ctaf/d ... mber=92464

Bill H.
Acoustic Propulsion Concepts

".......some day soon we'll be flying airplanes powered by pulsejets."

[Dang911]

Well, It just uses the same batteries as my drill any other combo crap, this was just an attachment, which I only paid $70 for, because I already had the batteries with the combo kit. I get VERY good battery life, I usually don't have to change a battery for a few working days using it. Although im not using it constant, just to start up a pulse jet. I would say at least 1 continuous hour, but that's a lot when you think about it....

[Dang911]

Also just stumbled upon this, a good buy for the price. CAN also be a blower...

http://www.harborfreight.com/cpi/ctaf/d ... umber=2489

[hinote]

I demo'ed this concept at the PJ meet last year with my "mini-Escopeta".

BTW one of the biggest problems we had at the meet was getting enough start air, to coax all the engines into resonance (some of them were VERY difficult to get going!).

Luckily, Chris ("Resosys") thought ahead and brought along a nice portable gen rig and an air compressor with a big tank, so everybody had enough air to do their thing. We really stretched Chris's goodwill with that one!! (thanks, Chris!).

Bill H.
Acoustic Propulsion Concepts

".......some day soon we'll be flying airplanes powered by pulsejets."

[hinote]

Also, I'm going to start playing with a permanent start-air line, set into the intake. SNECMA did this on the Escopette installation on the gliders (and probably others too).

Here's some evidence for SNECMA's use of the air-start method, on the Escopeta (taken from the so-called "SNECMA papers").

I drew-in a red arrow, pointing to the start-air tube.

Bill H.
Acoustic Propulsion Concepts

".......some day soon we'll be flying airplanes powered by pulsejets."

[Bruno Ogorelec]

Permanent starting lines will be a necessity for any serious engine, from demonstration use to actual practical application. If you used your engine on a flying machine, having one of those little blowers like Makita as permanent attachment, with air lines leading into intakes, might be cool.

[Mark]

http://cgi.ebay.com/100-cf-12-2L-Faber- ... dZViewItem

[larry cottrill]

Bill -

The thing I'd like to produce and market would be a somewhat smaller tank and regulator, with a 12VDC compressor just like yours, a small sealed battery (a gel battery or some such) and a spark coil, with a small storage area for the hose, spark wires and cables, and another storage area for small tools & materials, all in a suitcase-size package with comfortable handle. I don't see any reason such a thing couldn't be done, for a reasonable price. You could even have a nifty weatherproof connecter for your car or truck, so you wouldn't have to open the hood and fiddle with attaching clamps to the battery. Just about anyone serious about small pulsejets would find this beneficial - even my Dynajet could be started with it. The auto battery connection would be needed to run the compressor, of course, but would also be used to charge up the on-board battery.

L Cottrill

[Mark]

I think all new cars should come with pulsejet air starting tanks and auxillary ignition systems. My SUV has three 12 volt power outlets, one in the second row of seats and another in the cargo area. I wonder if they could handle a compressor like Bill's or would it necessitate going straight to the battery for power? I guess I could see just how many amps the little fuses are.
Mark