Originally Posted by earlwb

The problem with the baffle on the piston is that it tends to lead to pre-ignition or detonation as it starts to act like a glow plug when the engine is running. The baffle probably starts to get red hot.

I think this very unlikely as the OS15D actually used the piston baffle running in an assymetric head slot to promote swirl and flame pattern. Glow baffles would run hotter than diesels. Also, any red hot reciprocating bits are going to last a lot less than that 30-minute bottom end

But why would just about everyone else uses a flat top piston without a baffle in the model diesel engines. Granted it makes it easier to setup a contra piston if you don't have a baffle on the piston, but one could rig up something to prevent a contra piston from rotating in a engine.

Earl, my guess....baffled engines only have one port opposite the exhaust. In one side and out the other.
Most small diesel have a "ring" exhaust and multiple transfer ports.
The ETA 2.5, DC Rapier (green head) 2.5, OT, many Webra.
The exhaust and transfer are all around, which a baffle would defeat. Even the small OK, Cox glow have more than one exhaust and transfer port.
John

Maybe so, but many old diesels like the Drone for example only had one intake port and one exhaust port without a baffle. Now then some engines like the Drone sort of cheated a little, as they had a recess cut out of the piston on the intake port so that it directed the charge up and over in a loop pattern, thus they didn't have to put a baffle on the piston.
The old piston port induction engines were mostly all single intake port too with a flat top piston.

I tried my diesel without a baffle and the power was very low , so I soldered on a big one,

taller than stock , and it flys good I used silver solder ,it melts over 420C

a lot to do with the material, perhaps?...once upon a time a diesel without a Meehanite piston Could Not Be. Even Oliver just made do with a conical crown in this material; and after all, most other engines were not usually built for maximum attainable power; fancy pistons just weren't worth the candle if your transfers were drilled holes, or rough castings.
When Copeman tuned Olivers he polished the machined internal steps in the transfers but this was looked upon as hot stuff.

NX, how tall was the "stock" baffle?

From SafeLandings, I just had to add this link here.

Thanks again.

2 CYLINDER DIESEL TAPLIN TWIN 15CC running, vintage RC engine

2 CYLINDER DIESEL TAPLIN TWIN 15CC running, vintage RC engine(not nitro or glow !) (2 min 7 sec)

model taplin twin engine running (1 min 9 sec)

Stik with Taplin Twin in flight.3gp (2 min 9 sec)

http://www.rcgroups.com/forums/showthread.php?t=1478889

Geez they are landing planes right where they are riding bikes..... At the same time.

I Russia at one time they were doing general aviation and Parachuting and RC model at the one Aerodrome

And first woman in Space

Originally Posted by Chas

a lot to do with the material, perhaps?...once upon a time a diesel without a Meehanite piston Could Not Be. Even Oliver just made do with a conical crown in this material; and after all, most other engines were not usually built for maximum attainable power; fancy pistons just weren't worth the candle if your transfers were drilled holes, or rough castings.
When Copeman tuned Olivers he polished the machined internal steps in the transfers but this was looked upon as hot stuff.

NX, how tall was the "stock" baffle?

How tall ? you got me on that one , I have the stock piston here and the baffle is all bashed off where I tried to expand the piston by hitting it on a flat surface , I dont know , but I have a very tall baffle on my homemade piston ,,,,, to stop the transfer gasses just going straight out the exhaust , cant take it apart as the engine is working

Ladybird, an Edgar Westbury design. Notice the odd assembly of the conrods
onto the crankshaft, two end-plates rivetted together. Never seen this before.
This is 2,5cc date 1949.

That is a really odd setup for the rods. I never saw anything like that either.
Maybe they got the idea from some old steam engines or old early stationary engines.
That is a really unique design for a engine.

Reginald, thanks for sharing the 2.5 cc diesel Ladybird. I'm not familiar with Edgar Westbury designs. Yes, the assembly of the con rods onto the crankshaft with the two end-plates riveted together seems like a novel approach for such a small diesel.

And…..Here is more information on
Building the Taplin Twin Prototype Replica.

http://www.modelenginenews.org/ed.2006.08.html#eom

http://www.modelenginenews.org/taplin/index.html

John

Mr Wiz,
Those bikes are a big nuisance at where we fly. The field is a WWII time structure and today the land is under the ownership of the Indian Air Force. We as aeromodellers have permission to fly there but the runway is used by all and sundry for bike stunts, learning to drive and even as a thoroughfare. We have to be really carefull not to hit any one and damge either property, person or our own models.
If you see the other videos of the same person, you would see that he was flying a 120 size Super Sportster with the Taplin, thinking that it was a 15 cc engine. Even the videos are labelled such. I had to tell him it was not 15 cc and also sent him a link from the thread here to make him beleive that it was standard Taplin.
I am after the gent to sell it off to me or barter it for a HP 120 Twin . I hope he does

Mr. Wiz,
Things are a little different on the subcontinent...but it's a diesel !

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