Live prop with 912?

[Oscar]

I had a Gardner diesel in my boat. It had a TBO of 40,000 hours / 400,000 miles in a road going vehicle (buses, trucks).. It weighed (bare) about 1.4 tonnes. It produced about 110 hp at 800 rpm (rising to 130 at 1800 or so) 6.3 litres (from memory). Reliability in the face of abuse that left Rolls-Royce in the distant shade. The crankshaft weighs more than an installed Jab engine...

 

 

[Dafydd Llewellyn]

Dafydd you are probably aware of efforts to fit Peugeot diesels to Jodels.About ten years ago many of us got quite excited about the concept. PSA were building over a thousand of these engines every day, for use in several brands of vehicles. One Frenchman must have been deeply involved, and reported that he'd tested ten engines to destruction. The first failed at 12,000 hours (a dropped valve). Applying conservative rules, he predicted a service life of 10,000 hours.

Although potentially a world-beater, few conversions made it into the air. The extra weight and complications of a PSRU have made simple engines like the Jabiru quite appealing.

I had one of those engines, in a Pug 405 wagon. It gave peak torque at 2400 RPM, as I recall, and peak power at about 2800 RPM, so it would have worked quite well as a direct-drive motor - except that the crankshaft lacked the double main bearing at the output end, that is necessary in an aircraft engine to safely handle the gyroscopic loads from the propeller. It was far better than the rest of the car; but it was best to avoid lugging it below about 2200 RPM - which would suit a propeller load very well. It was still running well when I scrapped the car for other reasons, at around 330,000 Km.

 

The Jabiru engine was originally designed to have an installed weight no greater than a Rotax 582. It achieved that goal.

 

 

[facthunter]

When you have the cowl(s) off and are working on the engine, always consider it alive. The battery must be disconnected and make sure no one is inside the plane at any other time. The engine doesn't have to fire to be a hazard. Action by the starter can be dangerous The return of the oil on the Rotax depends on some gas passing the piston rings and is better achieved at a slow rate of turning, to allow this. New engines in good condition take longer. Nev

 

 

[pylon500]

'Burping' is also dependant on the position of the oil tank relative to the height of the engine.

 

Gazelle and Skyfox tanks tend to be higher and drain oil back into the engine.

 

Foxbat tanks tend to be lower, so most of the oil stays in the tank.

 

A cold engine will 'bleed' compression faster than a hot engine, so 'cold' turning will burp the tank quicker.

 

 

[BlurE]

When you're burping you want to hold the compression stroke for as long as possible and let the charge pass by the rings rather than just compress and decompress. (Its the blow-by causing crank case pressure that forces the oil back to the reservoir)

 

So you actually want to turn it quite slowly. But yes, always with great caution.

 

 

[Dafydd Llewellyn]

On the whole, I'd prefer the engine to have a scavenge pump.

 

 

[metalman]

On the whole, I'd prefer the engine to have a scavenge pump.

They obviously don't need one on this engine, so for they've been a phenomenal success as designed , other engine manufacturers would kill to have the same reliability

 

 

[bones]

well you see im just too lazy for my own good, i put my finger on the button on the dash for about 2 secs then check oil works everytime

 

 

[Geoff13]

I check my oil long before I get in the thing. :roflmao:That works everytime for me.

 

 

[rankamateur]

Plus anyone silly enough to move a prop without the switches being in the OFF position is asking for trouble anyway

It is called natural selection, Darwin made his reputation on it! Should be more of it.