The more things change... Powerplant Developments UK
 

Group,
Another entry on the opposed piston diesel front. With claims of "new" and "revolutionary" Powerplant Developments of merry olde UK has reinvented the opposed piston diesel. I love this style engine, it's one of the most efficient configurations. The idea isn't new though. They claim 100 HP at a weight of 166 pounds, or 11.9 stone. Not too bad. The guys at DAIR might be a bit upset about the "new" claims. PPD uses a 3 cylinder (6 piston) layout. All complaints about their new and improved claims aside, the engine does bare watching.
Bill Jepson

Lighter
 

How do they get lighter with two crankshafts and the associated stuff to connect them together?

gil A

me too
 

I've often wondered that myself. I suppose that the loss of two cylinder heads and the gain of a crankshaft has worked in their favor.

It seem like it would be a wash at best.

-mike

(august 31st, unemployed!)

Don't forget this is a 2-CYCLE diesel. No cams, no valves, no cam drive. If they use 3 gears to tie the cranks together taking the drive from the center gear it can be very light. The removal of the valve train and cylinder heads makes a big difference. For a point of reference, Renault's F1 V-10 started the trend of F1 engines using AIR SPRINGS on the valve train. Two advantages were gained, first: the air springs never fatigued, no breakage. (Didn't you ever wonder how they were reliably getting 18K RPMs in the newest cars without brakage?) More important to this discussion though was the fact that replacing the 40 valve springs of the V-10 with air springs saved almost 8 POUNDS! Remember these guys were spending thousands of dollars to lighten the car by ounces. Talk about a win-win. No fatigue failures, AND 8 pounds lighter! Getting back to the opposed diesel, No valves, no cylinder heads, no valve gear, and 3 cylinders serving the swept area of 6 pistons. Yes this engine has the potential of being MUCH lighter even with the 2 cranks, one of which they would need anyway. If you think about it they are only adding the weight of 2 pistons and rods etc... Because you would need at least a 4 cylinder conventional engine to make the same power from a standard poppet valve engine. Like the the Rotax 912.
Bill Jepson

Do you have a link?
 

I'd like to look at this "new" engine. Do you know if they have a website?

Thanks

The key innovation (i.e. borrowing the 1930's design) is that it's a two-stroke engine. This reduces weight be eliminating cam shafts and valves, and doubling the number of power strokes per revolution.

The problem with this design is coupling the power between the two crankshafts. The gearing may be the weak point in the design. The 1930's engineers minimized some of these issues by driving the prop from one crankshaft and the accessories from the other. That way the gearing was coupling less load... but does not seem like a robust solution.

The engine is not truly dynamically balanced, because the opposing pistons are offset in timing in order to allow efficient intake and exhaust 'strokes'. That will require some propeller vibration testing.

Ignoring the spark plug in the following, here it is:

Animation.

It is easy to find pictures of the engine, just search "Powerplant Developments" include the caps. I haven't found the website yet. In the past they timed the cranks as mentioned in another post which meant that the "trailing" crank delivered nearly 80% of the power. don't know if they are doing that.
Bill Jepson

Same principle as a Fairbanks Morse diesel........
http://www.sdrm.org/roster/diesel/fm/index.html

FDNY used an engine with similar technology in their "Super Pumper Complex"

If I recall correctly, 18 cylinders, three crankshafts in a triangle setup.

Engine originally from a locomotive.

Deltic locomotives
 

Mike.... that probably would be the English Deltic Locomotive used in the 60's and 70's

http://www.thedps.co.uk/staticpages/...php?page=locos

...but the engine was originally developed by Napier in Manchester, England for fast navy boats....

Nice BBC history of the engine here...

http://www.bbc.co.uk/dna/h2g2/A11815175

gil in Tucson

OK... I admit to being a trainspotter in my youth, and remember the Deltics coming out... but trainspotting soon became aeroplane spotting at Speke Airport (now John Lennon International... :) ...).... and we all know where that can lead to... :D