On the subject of engine technology have a look at this
http://www.limtechnology.com/Pages/concept.htm
It is a two stroke diesel design that uses cylinder porting for exhaust
but still uses valves in the cylinder head (un driven like check
valves) to intake boosted air and uses direct injection. The crank
case is not part of the intake system so it can be filled with oil as
in a conventional four stroke. It has excellent scavenging due to the
forced down flow through the cylinder during the exhaust/intake stage
and the fact that the entire valve area in the head is devoted to
intake only. It has excellent power to weight ratio and mechanical
simplicity due to lack of cam shaft and valve actuation and being
diesel requires no magnetos or ignition system. Since it has an oil
sump it does not require lubrication from the fuel as other two stroke
designs do which is a fact that makes them so offensive to the
environment. The engine is not prone to carb icing since it is a
diesel and has a wide open airway. All around this engine has so many
advantages that I want one! It would be cool to have the first
ultralight running on biodiesel!
Joe
[EMAIL PROTECTED] wrote:
The Napier Deltic was based on the Junkers Jumo aircraft diesel engine
developed before World War Two. The Jumo had one bank of 6 cylinders
and two crankshafts, so the Deltic was much more economical of crankshafts
and crankcases. Apparently Napier took out a licence from Junkers before
the war and acquired the technology but didn't go into production.
The Jumo by report was suited for running at a constant throttle setting
but couldn't take the variations in power needed for most military
operations. Apparently the piston which governed the exhaust ports and the
cylinder area around it tended to get too hot. It was used in the Junkers
JU 86 bomber-transport (and in the JU 86P high altitude reconnaisance
version where the suitability of the diesel for turbosupercharging
came in extremely handy; Paul Wilkinson's "Aircraft Engines of the World"
for 1944 says it could maintain sea level power to 32,000 feet) and in
Dornier patrol flying boats.
I've read casual references to the Deltic having maintenance problems.
There is a British book on the history of Napier ("The Napier Story?")
which may have more information.
L. J. K. Setright's "Some Unusual Engines" may have something on it; my
copy is long gone and my memory is dim.
British engineering journals of the 1950's will likely have information
about the Deltic.
Before the war Napier was apparently badly managed; this caused problems
with the Sabre aircraft engine. During the war the company was taken over
by Rolls-Royce due to the need to get the Sabre in reliable service and in
production. I've read that Napier had lathes at the time that were 100
years old. After the war Napier dissipated a lot of effort on the Nomad
compound diesel aircraft engine (which never went into production or
flew in a prototype aircraft) and the Eland gas turbine propeller engine
which saw very limited but not satisfactory service, and the Naiad
helicopter gas turbine, which I don't think went into production. I get
the impression that bad management continued, at least as far as
management focus went.
Doug Woodard
St. Catharines, Ontario, Canada
On Fri, 1 Jul 2005, Greg Harbican wrote:
Today while researching PT boats of WW2 and their younger cousins, the PTF's of the 1960's, I came across a engine called the Napier Deltic.
I was very intrigued with the idea of a high speed 2 cycle diesel, that used opposed pistons.
http://www.ptfnasty.com/ptfDeltic.html
http://www.ptfnasty.com/ptfdelticoperation.htm
http://www.intertrader.net/ptfdeltic.htm
If I understand correctly, they may be a bit more efficient than standard diesels, but, because they were so unorthodox they are somewhat obscure.
Does anyone have any knowledge of, or first hand experience with these engines?
Greg H.
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