Thanks for the nice reply. Now I have another question that, while it is about engineering, also relates to a market opportunity. First a bit of background - forgive me if you already know all this.

I fly gliders which are most often hauled into the air by a tow plane. Now glider tugs belong to the same engineering category as tractors used for tractor pull competitions - brute force and not much sophistication. For spark ignition, air cooled engines, glider towing is brutal work - red line temps followed by rapid chill down five or six times an hour.

Sometimes, the tug is asked to tow a 1300 pound glider into a mountain wave at 15,000 feet which can really tax the engine's cooling capacity as well as high altitude performance.

A Piper Pawnee with a 260 HP Lycoming O-540 has enough power for the job but, without some VERY careful operating techniques, overhauls come up often. Fuel consumption on a Lyc O-540 runs over 20 GPH. All this makes glider tows far more expensive than they should be. A Pawnee with a standard 2-blade prop is also noisy enough to prompt airport neighbor complaints.

A glider tug tows at about 65 knots and speeds above that are unimportant. The power package needs to produce maximum thrust for the HP at that airspeed. This fact suggests that a large, slow turning prop or perhaps a ducted fan could do the same job with much less horsepower - and noise.

A 160 - 200 HP Deltahawk looks like a perfect match for the job if it were matched to the correct prop. Would you please comment on this application?

Bill Daniels


"Dave Driscoll" wrote in message ...
Bill,

I love questions like this, you've already done the heavy lifting and pretty much nailed the merits. The merits start to look even better when you examine the possibilities of putting a clutched shaft on your existing turbo and electrically spin the compressor side as required (reduces weight, gains you the HP that is always being sucked up by the blower which is compressing air at a much lower efficiency than the turbo, etc.) There are also a mess of other possibilities that while more complex from an engineering standpoint offer "better" solutions for certain mission profiles. These include compressed air starts, fully electrical turbos, clutched superchargers, centrifugal or screw compressor supercharges instead of roots type, the list goes on.

The selection of our current solution was a combination of the desire for mechanical redundancy, the use of off the shelf parts (off the shelf 5 years ago mind you), and the need for something that didn't require a huge amount of engineering effort to shoe horn into our package. That said, undoubtedly this is one of the areas that will see modification as time passes, and it wouldn't surprise me in the least if 5 years from now there is a DeltaHawk model that in addition to the electric turbo has full FADEC fuel control, an electric water pump, and an integrated starter/generator. Imagine what that will do to the weight and fuel efficiency. Additionally, due to the modular design of all of these components on the DeltaHawk, all of these items are a external to the engine case and for the most part are a bolt on proposition.

Dave Driscoll
DeltaHawk LLC


Bill Daniels wrote:

Dave, I like the Deltahawk package the way it is, but I do have a
hypothetical question.

What are the merits, of lack thereof, of using an electrically boosted
turbocharger to supply combustion air for starting or flight idle? It would
seem, at first glance, to be a simpler and lighter solution than using both
a roots supercharger and a turbo in series.

Bill Daniels


"Dave Driscoll" wrote in message
...
All,

In addition to being an lurker and occasional poster on RAH, I also
happen to be one of the engineers responsible for the DeltaHawk (or the
sole reason the engine hasn't been in full production for the last 3
years according to the marketing guy). In any case, as this is one of
my few areas of RAH expertise, I'd be happy to answer any questions that
people may have regarding the project.

The web site

www.deltahawkengines.com

is generally pretty up to date, but there are certainly always specific
questions that a FAQ won't answer.

Dave Driscoll
DeltaHawk LLC

geo wrote:

Here's an interesting new diesel engine with much lower operating costs.
Looks like it would fill the bill for a Glass Goose (which I'm
considering)
very nicely. Waddya think? http://www.deltahawkengines.com/object00.htm