Mini RC diesel engines

[y2blade]

I had no idea these were out there!

Look at the little rockers!








Specifications:
Cylinder bore x stroke 22.3 x 17.0 mm
Cylinder displacement 6.64 cc
Weight 370g
Max power 0.7HP/12,500rpm
Practical speed range 8,500~13,000 rpm
Idling speed 2.500~3,000 rpm
Critical speed 14,000~ rpm
Carburetor Enya GC type 5.5mm (with special starter system)
Cylinder liner and piston Steel liner, ringed Al. piston
Size of propeller 12 x 6, 11 x 6~7, 10 x 6~8 in.
Glow plug Enya No. 3
Suitable weight of plane 2.0~3.5 Kg

http://www.singahobby.com/?q=node/17274
http://www.youtube.com/watch?v=j1rteehLjSo

[vdubbin]

No torque figures? They're missing a trick there! I wonder if it's 2 stroke or 4?
I remember one of the RCCA lads (think it was Kevin Hetmanski) putting a 4 stroke mill into 1/14 Artic (possibly a Tamiya) years ago. I think the main problem was keeping everything cool as there was much less airflow compared to an aero installation.

[Silver993tt]

vdubbin said:

No torque figures? I wonder if it's 2 stroke or 4?

er, it has valve rocker arms, so I think it's probably a 4-stroke

[Robb F]

vdubbin said:

No torque figures? They're missing a trick there! I wonder if it's 2 stroke or 4?
I remember one of the RCCA lads (think it was Kevin Hetmanski) putting a 4 stroke mill into 1/14 Artic (possibly a Tamiya) years ago. I think the main problem was keeping everything cool as there was much less airflow compared to an aero installation.

Unless there is a tiny supercharger I reckon it's 4-stroke.

Cool little things though.

[tr7v8]

It isn't a diesel it is a glow plug motor. It runs on methanol & oil mix, same as a 2 stroke so total loss.
Yes it is a 4 stroke, there are supercharged ones but they are rare & expensive. Commercial ones have been around for a while around 30 years Plus.

[MartG]

Model 2 stroke diesels have been around for a long time - I was using these back in the early '70s

http://www.eifflaender.com/

[Robb F]

MartG said:

Model 2 stroke diesels have been around for a long time - I was using these back in the early '70s

http://www.eifflaender.com/

Well two stroke diesels have been around since the 1890's, just not naturally aspirated ones.

[MartG]

Robb F said:

just not naturally aspirated ones.

None of the ones I had used forced induction - all were NA. My first experience with a turbodiesel didn't come until 1980 - Rolls Royce V8 diesel generators onboard the containership SS ACT1

[Robb F]

A proper two stroke diesel engine can not work without forced induction.

[MartG]

Robb F said:

A proper two stroke diesel engine can not work without forced induction.

Well there's certainly no trace of forced induction on any of these engines, yet they work just fine http://www.eifflaender.com/enginepics.htm

[Robb F]

How does air get into the cylinder?

[MartG]

The same way as with any two stroke engine, be it petrol, glowplug or diesel

[Robb F]

MartG said:

The same way as with any two stroke engine, be it petrol, glowplug or diesel

But in petrol and glow plug engines the air and fuel is premixed and then pushed into the cylinder by the pressure of the down stroke of the piston. In a proper diesel engine only air is drawn into the chamber and fuel injected into the cylinder once compressed. So your PAW engines are not proper diesel engines.

A diesel engine is defined as "An internal-combustion engine that uses the heat of highly compressed air to ignite a spray of fuel introduced after the start of the compression stroke."

[tr7v8]

Robb F said:

MartG said:

The same way as with any two stroke engine, be it petrol, glowplug or diesel

But in petrol and glow plug engines the air and fuel is premixed and then pushed into the cylinder by the pressure of the down stroke of the piston. In a proper diesel engine only air is drawn into the chamber and fuel injected into the cylinder once compressed. So your PAW engines are not proper diesel engines.

A diesel engine is defined as "An internal-combustion engine that uses the heat of highly compressed air to ignite a spray of fuel introduced after the start of the compression stroke."

They are CI or compression ignition engines, they run like a diesel (hence the name) but take in a fuel air mix. They still rely on high ompression to ignite the fuel. The fuel in this case being ether/paraffin/oil
it is the ether that lowers the flashpoint & gives the bang. They originate from the late 40s early 50s.

[Robb F]

So it's not a diesel?

I must apologise for derailing the thread so much though, that was my fault

[Kneetrembler]

MartG said:

Model 2 stroke diesels have been around for a long time - I was using these back in the early '70s

http://www.eifflaender.com/

These were around way back in the early 60's,

[MartG]

Robb F said:

A diesel engine is defined as "An internal-combustion engine that uses the heat of highly compressed air to ignite a spray of fuel introduced after the start of the compression stroke."

Agreed, except that the fuel can be introduced as a fuel/air mix via a carb, not necessarilr injected. The critical thing is that it's the heat generated by compression that ignites it.

[MartG]

Robb F said:

But it has to be introduced after the compression stroke has started so a carb wouldn't work as there isn't a lower pressure inside the cylinder than atmosphere and all valves would have to be closed.

If fuel goes in before the combustion stroke it isn't a diesel engine.

Why does it matter exactly when the fuel/air mix is introduced into the engine - the critical thing is that diesels use compression to ignite the fuel, irrespective of how it got there.

You need to look at how these 2 stroke engines work - the carb doesn't feed into the cylinder, it feeds into the crankcase drawn in by the vacuum created by the piston going up on the compression stroke. As the piston descends on the power stroke it uncovers the exhaust port and then the inlet port. No valves. Scavengine relies on the partial vacuum caused by the exhaust gases exiting at speed to help draw in the fuel/air mix from the crankcase. All small 2 strokes work like this, both glow or diesel.

[Robb F]

Since the dawn of time have been taught diesel engines are defined by the fact the fuel is added into the chamber after the air is compressed. You cannot argue with a diagram and experience so thanks for teaching me something.

[MartG]

You're welcome