The Bexmotor lives on

[fly_tornado]

[geoffreywh]

Bex's is not a piston ported twostroke, his has poppet valve (s) . The one shown going into the machining centre had no cylinder head, but what appeared to be ports in the cylinder. That's what it looked like to me anyway...Personally I'd rather see a sleeve valve jobbie

 

 

[Oscar]

Having worked extensively on a two-cylinder, opposed-piston diesel 2-stroke, specifically designed to drop into Jabiru-powered drones, (so same package size), I believe I have some genuine experience. We got it to running stage, but it needed more development and the funds ran out. This was not a back-yard lash-up, we had the full resources of Phil Ainsworth's Technology Park machining facility behind us - capable of producing everything including the injector pump!.

 

The Deutz DZ710 was a successful opposed-piston aero engine, of 2700 hp capability, and weighing 1450 kgs. That weight provides a hp/lb figure of .84 - which is NOT shabby. A Lycoming 0320-D says .67 hp/lb, a Jab 2200 says..58 HOWEVER: all of those figures are not necessarily directly comparable, because in the Jab case it is 'installed' (or Ramp) weight (actually, what it weighs dry but ready-to fly), and we don't know the configuration for either the Lycoming or the Deutz.

 

There are several problems for a piston-ported 2-stroke horizontally-opposed diesel engine. The first of these is that it requires forced induction in order to scavenge the combustion area until at running revolutions. The D710 had forced induction. The next, is the need for heater plugs unless the c/r is very high indeed - requiring massive (and heavy) strength. The third, is (in small-capacity engines), the physical area required for heat transfer from the very compact size of the combustion area.

 

This is one time that 'a good little 'un' beats 'a good big 'un' doesn't hold true. The cubic rule for area vs. size works in the favour of the larger engine -especially if you are going for air-cooled. When you are trying to cram everything: induction, exhaust and cooling - into a compact size for a 100 hp or so engine, it becomes extremely difficult. The ancillaries - including the source of forced induction - become a large part of the 'installed' weight and complexity. The ancilliary penalty reduces with size.

 

There is a place for 2-stroke, horizontally-opposed piston diesel engine in aviation - but it's probably unlikely to be for the 100-hp or so class.

 

 

[spacesailor]

Oscar

 

The aero engine has a built in super-charger, called "the propeller", it just needs to be configured to get that big turbo utilized.

 

And whatever happened to the "Commer two-stroke diesel" of the sixties

 

spacesailor

 

 

[Dwilly]

Commer knocker?

 

 

[planedriver]

Pretty noisy old donk. You could hear one coming a great distance away because of it's distinctive sound.

 

(For overseas readers, donk is an Aussie slang term meaning donkey. i.e. engine which does all the hard work)

 

 

[Yenn]

is a commer knocker an earlier version of a Jab knocker. At least you wouldn't get run over by one you could hear it for 5km

 

 

[cooperplace]

these opposed piston engines are very large; might be Ok for a truck or a ship; will be too big (IMHO) for a car or light plane.

 

 

[IBob]

I believe they had the 3 crank triangulated version of that in some fast warships. I recall being told they were difficult to maintain (inevitable, I suppose, compared with the conventional straight marine engines), also that they self destructed if the throttle was opened too rapidly.

 

However, with 'modern' engineering and computerised engine monitoring & control, it seems likely that some of these more challenging configurations may succeed.

 

 

[horsefeathers]

I believe they had the 3 crank triangulated version of that in some fast warships. I recall being told they were difficult to maintain (inevitable, I suppose, compared with the conventional straight marine engines), also that they self destructed if the throttle was opened too rapidly.However, with 'modern' engineering and computerised engine monitoring & control, it seems likely that some of these more challenging configurations may succeed.

A Napier Deltic is the beast. It was a three bank triangle, with a crankshaft at each corner of the triangle

 

 

[Downunder]

However, with 'modern' engineering and computerised engine monitoring & control, it seems likely that some of these more challenging configurations may succeed.

Yes, with modern metallurgy and machining tollerances I also recon some older designs are worth a look.

 

Perhaps sleeve valve engines.......

 

Interesting new engine from Mercedes...

 

Next-gen Mercedes engines bring 48V electrics and the return of the straight six

 

 

[IBob]

A Napier Deltic is the beast. It was a three bank triangle, with a crankshaft at each corner of the triangle

I grew up a few hundred metres from a station on the Aylesbury line in the UK. The trains were diesel electric and had this truly wonderful bass blatting noise as they first started to move away. Echoed all over the village. As did the big stationary engine that still ran the line shafts in the local woodyard and joinery.....

gah....I went on YouTube to try and find the sound....and stumbled on an entire subculture of train noises!!!