Jet-A fuelled 180HP piston-engine type-certified

[facthunter]

A lot of supercharging in planes is used for altitude power compensation. Some of the mechanical ones are 2 speed where you engage the higher gear at mid altitudes. The Turbo P&W 1830 in the Liberator was for high altitude flight. That engine is the only turbo'd P&W I know of.  The best specific fuel consumption aero engine has 3 turbine "power recovery" units using the exhaust energy from a radial engine and coupled to the driveshaft. Used on the Lockheed Constellation (sometimes called the Consternation for their lack of reliability)   Nev

[facthunter]

I doubt you could market a non supercharged diesel for road use today. It's so much a part of engine management of a diesel to ensure complete combustion and improve driveability, power output and drop cruising RPM's.. Nev

[BrendAn]

7 minutes ago, facthunter said:

A lot of supercharging in planes is used for altitude power compensation. Some of the mechanical ones are 2 speed where you engage the higher gear at mid altitudes. The Turbo P&W 1830 in the Liberator was for high altitude flight. That engine is the only turbo'd P&W I know of.  The best specific fuel consumption aero engine has 3 turbine "power recovery" units using the exhaust energy from a radial engine and coupled to the driveshaft. Used on the Lockheed Constellation (sometimes called the Consternation for their lack of reliability)   Nev

a friend of a friend used to fly the super conny on the kangaroo route and he could not recall a landing in sydney with all engines working.

Edited May 23, 2023 by BrendAn

[facthunter]

They rarely got to London without an engine change. One Boeing Strato Cruiser lost 3 engines on a flight.. The Connie at HARS seems to  go pretty well but maybe it's derated and on lower octane fuel. The 130/145 avgas fuel was most common. It wouldn't be around anywhere now.  Nev

[Thruster88]

Interesting that the super connie had power recovery turbines helping drive the crankshaft. 

 

 In 1953, R-3350 Turbo-compounds were made available for civil use. Lockheed incorporated them into the L-1049C, which first flew on February 17 of that year. The R-3350-972-TC18DA-1 turbo-compound engines on the L-1049C had a new turbine system, the Power Recovery Turbines (PRT). Each engine's exhaust gas flowed through three turbines, increasing power by 550 hp (410 kW).

[onetrack]

Qantas came very close to destroying their superb flight record when one of their Super Constellations crashed on takeoff at Mauritius in 1960 after No. 3 engine failed substantially on takeoff.

The crew rejected the takeoff but were unable to stop before the end of the runway, and crashed into a ravine. With the full fuel load, the Constellation caught fire and burnt out, thus making the crash investigation more difficult.

Of the 50 pax, 20 were slightly injured, including a hostess who suffered a broken leg.

 

https://www.baaa-acro.com/crash/crash-lockheed-l-1049g-super-constellation-port-louis#:~:text=Circumstances%3A,three suffered a technical failure.

[danny_galaga]

On 21/05/2023 at 1:00 PM, facthunter said:

You have to scavenge a two stroke positively, especially IF you are not involving the crankcase as away of doing it.. You don't need a lot of boost to do that if that's the way you go. You can use a more normal OIL system as well. Starting would have to provide boost before the motor was started. Either a rotor(s) positive displacement engine driven blower or electric? The TURBO only works once the motor is running.  Lots  of turbo's will damage your ears.  Nev

Why not tuned pipes?

[facthunter]

It could work but only at certain revs unless the exhaust was adjustable. You still have to get it started. Nev

[onetrack]

Quote

Lots  of turbo's will damage your ears

Turbos don't produce the same noise level as Roots-type superchargers, because the rotation of the curved lobes in a Roots-type blower, with their exceptionally-close rotor clearances, is what produces the ear-splitting scream.

In fact, that clearance level is so tight, that if a Roots-type blower is operated outside its designed parameters, it can seize up, with obviously disastrous results.

 

A Roots blower doesn't actually compress air to any substantial level, it simply pumps it without any real pressure increase. So despite the fact that GM 2 stroke diesels were supercharged, they were still defined as naturally-aspirated engines.

The Roots blower on an engine simply acts to pull in increased volumes of air to fill the vacuum in the intake manifold.

 

However - a turbocharger, thanks to its turbine design, actually pressurises an engine intake. You can get turbochargers to produce over 40psi of positive intake pressure.

Naturally, this makes for substantially increased power if the engine is built to take it. However, both superchargers and turbochargers have a problem with the heat produced from the compression of the intake air, so heat exchangers or "charge air coolers" are often used to remove that unwanted heat, and to increase the air density going into the engine.

Heat exchangers or charge air coolers are most commonly used in conjunction with turbochargers, because of their levels of heat produced from the compressed intake air.

 

Edited May 26, 2023 by onetrack

[Blueadventures]

Always rapt with the 71 series Detroits in marine engine power.  Very reliable, though a bit oily and performed even if a rocker broke; just lost about 150rpm.

Edited May 26, 2023 by Blueadventures

[skippydiesel]

On 23/05/2023 at 9:30 AM, onetrack said:

Skippy - Because the supercharger is simply necessary to scavenge the combustion chambers - but the turbocharger is there to improve the power level and efficiency, by utilising the waste exhaust gases. Two different accessories with different jobs to do. 

Scavenging can be achieved by either a supercharger or turbo charger - there must be more too the decisions to have both.

Edited May 26, 2023 by skippydiesel

[facthunter]

You have to specify whether it's a 2 stroke or a four stroke when you discuss this. . There's a world of difference in how you deal with them. Turbochargers are very common on even small Cars whether Petrol OR Diesel these days.  There's still the odd engine with a mechanically driven supercharger. Mercedes with "KOMPRESSOR" on them. Ford and GM have done this. Twin turbo helps turbo lag. ALL ways of increasing output have to deal with the excess HEAT that comes with it. Nev

[Thruster88]

3 hours ago, skippydiesel said:

Scavenging can be achieved by either a supercharger or turbo charger - there must be more too the decisions to have both.

As described above if it only has the turbocharger it would not start or even be able to idle. It is a 2 stroke however the crankcase is not used to pump air into the cylinder like a Rotax 582.

 

The other advantage of the turbocharger is to "unload" the crankshaft driven supercharger at high power setting, this fixed displacement pump would become a fixed displacement motor when the turbo comes on boost giving greater fuel efficiency. The supercharger would then drive the crankshaft like the power recovery turbines in a super constellation.  

Edited May 26, 2023 by Thruster88

[skippydiesel]

47 minutes ago, Thruster88 said:

As described above if it only has the turbocharger it would not start or even be able to idle. It is a 2 stroke however the crankcase is not used to pump air into the cylinder like a Rotax 582.

 

The other advantage of the turbocharger is to "unload" the crankshaft driven supercharger at high power setting, this fixed displacement pump would become a fixed displacement motor when the turbo comes on boost giving greater fuel efficiency. The supercharger would then drive the crankshaft like the power recovery turbines in a super constellation.  

Interesting!  I like it. Is your suggestion, speculation or inside  knowledge/fact?

 

But what if it only had the supercharger - pressurised air from the get go/start of cranking??

[facthunter]

That's how the GM works Scavenge only. not recommended to idle slow. due gear drive and blower inertia. The same blower is used on Nitro cars/Rails driven by a toothed belt.  Nev

[Thruster88]

I have no knowledge of this engine, just experience and knowledge of how hydraulic gear pumps and motors work. Air or oil they are just fluids. The roots supercharger is just a type of gear pump.

[facthunter]

With a stretch of the imagination. The 3 lobe spiral Rotors are connected by gears to keep them in the correct relationship but Gears work in a similar way. They are a positive displacement thing unless they are damaged by FOD. but can pump considerable pressures. in four strokes if matched correctly to the engine displacement.   IF the engine backfires they usually lift off the block. Nev