The more things change... Powerplant Developments UK

[Mike S]

Gil, you hit it on the nose.

Quote from article about the pump module--"Powering this pump was an 18 cylinder, twin turbo Napier-Deltic T18-37C locomotive diesel."

I did a bit of quick searching, couldnt find any photos. I think the hyphenated name must have confused Google.

[az_gila]

Originally Posted by Mike S

Gil, you hit it on the nose.

Quote from article about the pump module--"Powering this pump was an 18 cylinder, twin turbo Napier-Deltic T18-37C locomotive diesel."
.....

So the memory isn't always the first thing to go.....

gil A

[JetA4GA]

If they (PPD) succeed in certifying this Powerplant (to FAR 33) and gain enough positive field experience with competitive pricing/support, then ROTAX need to be worried, especially in Europe where the latter is very popular. 2 strokes diesel might be OK for the 100 HPish segment but 4 strokes direct drive diesel need to be considered for the 200-500 HP range...decent and proven technology that delivers lightweight/performance/reliability is now on the rise and that is much better than the ones used by the TAE and SMA or, like engines.

[flytoboat]

These folks were at OSH with the 100 HP engine. They are working on a 360HP version and a 200HP version. Nothing flying yet though...
Here's the link: http://ppdgemini.com/

[breister]

Originally Posted by JetA4GA

If they (PPD) succeed in certifying this Powerplant (to FAR 33) and gain enough positive field experience with competitive pricing/support, then ROTAX need to be worried, especially in Europe where the latter is very popular. 2 strokes diesel might be OK for the 100 HPish segment but 4 strokes direct drive diesel need to be considered for the 200-500 HP range...decent and proven technology that delivers lightweight/performance/reliability is now on the rise and that is much better than the ones used by the TAE and SMA or, like engines.

Don't see why this idea wouldn't scale to 200hp. Bigger pistons, more cylinders, whatever.

DeltaHawk is also 2-stroke, and is reportedly nearing certification. Theirs IS direct drive. The 2-stroke has an advantage in that it acts as if it has more pistons, with each "power stroke" providing less of a jolt than an equivalent 4-stroke. The result should be smoother operation.

[rv6ejguy]

Not to rain on the parade, but the hard part for the new guys (besides meeting the claims and longevity) will be to be able to produce in numbers at a cost less than the current offerings and with proper, widespread tech support. This is very difficult to do in a short period of time. Rotax has a pretty massive network worldwide with good training support and documentation.

If we look at how long it took Jabiru to get to where it is now and how poorly Wilksch, SMA, Deltahawk and Thielert have done after a number of years in the market, you'll realize that this is a hard nut to crack.

I wish them well but believe that any certified engine will be massively expensive and massively expensive to certify. All comers better have big financing behind them. I think it is a huge mistake business wise to concentrate initially on certifying new engines where there is a huge experimental market worldwide for manufacturers to recover initial investments on and refine their designs in actual use before proceeding to certification.

[Rotary10-RV]

Guys, This engine is direct drive to the propeller. The only gearing involved is 1:1 to gear and time the two crankshafts together. They don't need a gear reduction for RPM. I really like this style of engine it has many advantages. The super long effective stroke and good cylinder filling are both great for getting efficiency up. The Fairbanks-Morse engine was mentioned along with the Napier Deltic, and both of these engines were considered very efficient in their time. Modern materials applied to the same basic design should really produce a winner. Making it beyond the prototype stage is the tough part, as Ross mentioned. If you really wanted to make a stir it would be a great idea to develop in secret and be ready to produce when you release the engine to the public. I think people would nearly fall over backwards if when asked, "When will engines be available?", your answer was, "As soon as your check clears!"
Bill Jepson

[Joel]

Their website is at www.ppdgemini.com. It came from a podcast on AvWeb.com.

Plus: Full rated hp to 5kft, compact, and designed for aircraft. Negative: no torsional damper. Interesting concept, but I want to see more proven field useage. Could be a winner. Hope it is.

Joe

[teookie]

I agree with ROTARY10-RV, the gearing is a non-issue with this design. This is due to no small amount of existing analysis on gear design and materials that can be referenced to easily design a bulletproof gear train.

I don't know why so many people cringe when they hear the word "gears". We all use them everyday in our cars, and I've seen the gears from 50,000 lb thrust jet engines that were surprisingly small. If designed and setup correctly, gears are great!

[flytoboat]

The rep at OSH told me that on the Gemini 100 engine, the cranks rotate at 4000 rpm and the prop at 2500 rpm for a 1.6:1 ratio.