Caterpillar/Wright 1820 into a diesel, could it be used in aircraft such as B17?

[pinsog]

Caterpillar converted the Wright 1820 into a diesel and used it in the Sherman Tank. Could that engine, as a diesel, be set up to power a B17 or a B24 or even a Wildcat? The benefits being both longer range and less explosive fuel being carried. I can not find any info on the Caterpillar D200A as they called it, except that it was used in the Sherman tank.

Does anyone know how much weight the engine gained when it was diesel-ized?

 

[tyrodtom]

I've got the book the American Arsenal, it calls it the Ordnance Engine RD-1820, it's dry weight is listed as 3536,with 497 hp and 945 lb-ft of torque while the Wright G-200 is listed at 1350 lbs with 800 hp, and 1850 torque.

If those figures are accurate, it's weight alone would make it a very unlikely aircraft engine.

 

[Shortround6]

Something sounds way out of wack with those numbers. Perhaps the Ordnance Engine RD-1820 weight includes cooling fans, fan drives and shrouds used in the tank installation, perhaps a misprint, perhaps a combination?

For a comparison Guiberson offered the A-1020 aircraft diesel which was similar to the T-1020 used in the M-3 light tanks. I believe they were based on the Wright R-975 Whirlwind. The Guiberson used 3mm more bore than the Whirlwind 9130 vs 127) or 0.125 inches. the Guberson was good for 340hp at 2250rpm from 650lbs and had no supercharger. The Wright was good for 450hp at 2250rpm using 36.5in MAP and 91 octane gas from 675lbs. A Whirlwind with a lower supercharger gear was good for 365hp at 2100rpm on 73 octane gas. These are take-off ratings.

The Guiberson was getting about .33 hp per cu. in. and about 1.91 lb per hp. It was using a 14:1 compression ratio.

A Cyclone might be expected to hit around 600hp or so as a Diesel for aircraft use. tank engines were usually de-rated for tank use. No 5 min or emergency power settings, more like the "normal" or max continuous aircraft ratings. a wright G-200 was good for 1100-1200hp for take-off depending on exact model. 800hp is below max continuous and cruise.

In any case even if the Diesel version is only 1300-1400lbs in aircraft trim it is putting out about 1/2 the power of the Gasoline engine.

 

[pinsog]

Something sounds way out of wack with those numbers. Perhaps the Ordnance Engine RD-1820 weight includes cooling fans, fan drives and shrouds used in the tank installation, perhaps a misprint, perhaps a combination?

For a comparison Guiberson offered the A-1020 aircraft diesel which was similar to the T-1020 used in the M-3 light tanks. I believe they were based on the Wright R-975 Whirlwind. The Guiberson used 3mm more bore than the Whirlwind 9130 vs 127) or 0.125 inches. the Guberson was good for 340hp at 2250rpm from 650lbs and had no supercharger. The Wright was good for 450hp at 2250rpm using 36.5in MAP and 91 octane gas from 675lbs. A Whirlwind with a lower supercharger gear was good for 365hp at 2100rpm on 73 octane gas. These are take-off ratings.

The Guiberson was getting about .33 hp per cu. in. and about 1.91 lb per hp. It was using a 14:1 compression ratio.

A Cyclone might be expected to hit around 600hp or so as a Diesel for aircraft use. tank engines were usually de-rated for tank use. No 5 min or emergency power settings, more like the "normal" or max continuous aircraft ratings. a wright G-200 was good for 1100-1200hp for take-off depending on exact model. 800hp is below max continuous and cruise.

In any case even if the Diesel version is only 1300-1400lbs in aircraft trim it is putting out about 1/2 the power of the Gasoline engine.

If the supercharger is re-installed (if it has been removed), and the engine will still turn the same rpm as the gas burner, wouldn't the increased torque from the diesel still spin the propeller at the same rpm?

I guess my point is, HP doesnt tell the whole story. Those of us in the US are familier with the big 3 automakers diesel pickups. In the early 90's when they all three finally had turbo's, they didn't have really high horsepower, but they had so much torque that they would pull circles around gas powered trucks with 50% more horsepower. I wondered if the same thing might apply to spinning a prop

 

[tyrodtom]

I admit the figures don't make sense to me either, especially the torque numbers for the diesel.

But with the much heavier crank, rods and pistons to take the higher compression, i'm not too sure you're gonna see the same RPM with the same turbo.

 

[Shortround6]

There is an old saying that torque is acceleration and that horsepower is speed.

 

[pinsog]

There is an old saying that torque is acceleration and that horsepower is speed.

If 2 engines are turning the same prop at the same rpm, speed should be the same.

I admit I don't know the answer, that is why I am asking.

If this engine was diesel-ized, supercharged like the gas motor and could turn the same rpm, how much hp could you get out of it? Or how much torque? And how much would it weigh?

 

[wuzak]

If 2 engines are turning the same prop at the same rpm, speed should be the same.

And the power would be the same for teh same thrust/speed.

If the Diesel has more torque at the same propellor rpm as the petrol version it has more power.

 

[Siegfried]

I've got the book the American Arsenal, it calls it the Ordnance Engine RD-1820, it's dry weight is listed as 3536,with 497 hp and 945 lb-ft of torque while the Wright G-200 is listed at 1350 lbs with 800 hp, and 1850 torque.

If those figures are accurate, it's weight alone would make it a very unlikely aircraft engine.

The British modified the Merlin III to make the Meteor tank engine. It lost over half its power and gained considerable weight though it was still far lighter than other tank engines.

For tank use the Merlin had its supercharger, reduction gear, and other equipment removed from its camshaft, greatly simplifying its construction. It had cast, rather than forged, pistons, and was de-rated to around 600 bhp (447 kW), running on lower-octane pool petrol instead of high-octane aviation fuel. In addition, because weight saving was not so important for a tank engine, some of the Merlin's more expensive light-alloy components were replaced with cheaper, steel components in the Meteor X version. It was also envisaged that the Meteor would use some components rejected on quality grounds for the Merlin, i.e. Merlin scrap. In 1943 an acute shortage of blocks was met by dismantling surplus older marks of Merlins.

An R-1820 or R-1830 developed as a turbo-diesel would likely make a superb aircraft engine. Diesels have disadvantages compared to gasoline engines however all can be overcome by turbo charging which they 'love'. There is no danger of preignition and the exhaust gas temperature is MUCH lower (550 versus 850C) due to greater dilution and higher efficiency and so the exhaust manifolding and turbine are far less stressed.

The higher compression ratio and higher peak pressures require greater strength, this could also be achieved by reducing the bore somewhat or better reducing the bore slightly and using the extra space for bigger or more head bolts etc.

The Germans did have aviation diesels (Jumo 205) as did the Russians (Charomskiy ACh-30)

 

[Siegfried]

And the power would be the same for teh same thrust/speed.

If the Diesel has more torque at the same propellor rpm as the petrol version it has more power.

Agreed.

Power is the only important factor however engines with peaky distributions of either torque or power may need exceedingly complicated gearboxes (many stages and fast changing) this is mainly an issue in off road vehicles where you want steady torque that won't break traction.

Power = Torque x angular velocity
(angular velocity = revs in radians/sec)

 

[barney]

If 2 engines are turning the same prop at the same rpm, speed should be the same.

If two engine are turning the same prop at the same rpm and the prop pitch is the same, speed should be the same.

 

[Shortround6]

In these aircraft engines peak power was usually governed by two things. One was the ability to dissipate heat. the other is the ability to put out the power and not break things like pistons, connecting rods, cylinder hold down bolts, etc.

Diesels operate at higher peak cylinder pressures than gasoline engines which means they need to be stronger. The average or mean pressure is often lower so that actual power is lower.

 

[davebender]

R-1820 or R-1830 developed as a turbo-diesel would likely make a superb aircraft engine

Maybe during 1935. By 1940 the R-2600 engine was in production and the R-2800 was in the pipeline. The USAAC is not going to select a 1,000 hp R1830 diesel over a 1,600 hp R2600 gasoline engine.

The B-17 and B-24 were underpowered compared to many contemporary WWII era bombers. Perhaps the USAAC could develop a turbo-diesel version of the R2600 to power late war versions of these aircraft.

 

[Shortround6]

The R-2600 was a dead duck for late war use no matter what was done to it. Anybody who spent more than 30 seconds and dime on B-17 and B-24 major variants for late war use should have shot as a saboteur. The B-29 and B-32 were already well in hand.

The B-17 and B-24 were underpowered for take-off. Power at 20-25,000ft is much closer to contemporaries.

The diesel aircraft engine offered too little gain in return for too much effort to sort it out.

 

[fastmongrel]

Diesels of the period had poor throttle response compared to equivalent aero engines. Not sure if this would have made any difference to a bomber flying on its own but one in a Box formation is going to keep the pilot in a sweat.

 

[davebender]

The B-29 and B-32 contributed nothing at all to the European air war. That makes it worthwhile to consider improvements to the B-17 and B-24.

IMO diesel engines are not the answer. But R2600 gasoline engines might provide a substantial increase in range / payload.

 

[Shortround6]

B-29 and B-32 were being worked on in 1940-41. That makes it a little difficult to squeeze in an R-2600 powered bomber. Work would have to have started in 1939. Since a turbo-ed R-1820 or R-1830 offered similar cruising power at 20,000-25,000ft as a non-turbo-ed R-2600 Increase in range / payload would be minimal without a new airframe with much higher gross weight. Modified B-17 with R-2600s just lost about two tons of payload (bombs/fuel) due to engine swap unless the gross weight can be increase (heavier landing gear, new spars, reinforced fuselage etc.)

 

[davebender]

B-17E. 51,000 lbs Loaded weight.
B-17G. 54,000 lbs Loaded weight.

3,000 lb increase during time frame when R2600 engines would be installed. I think max takeoff weight increased even more.

 

[Shortround6]

Max weight went to around 72,000lbs. the trouble is that an these increase weights the ability to maneuver went way down as did the ability to land with out jettisoning weight and even things like engine out control-ability speeds change.

Bombers were not built to the same limits as fighters and may have been built to a 3.8 G limit at normal take-off weight + a 1.5 safety margin. A 55,000lb bomber at 3.8 Gs is limited to 2.9 Gs at 72,000lbs. This of course assumes an even distribution of the higher weight which was never going to happen in real life.

your idea is to replace four 1320lb engines with four 1965lb engines, a 2580lb change not including larger heaver cowlings, engine mounts and more importantly, larger heavier propellers ALL a number of feet in front of the normal center of gravity. Maybe we can just move the fuselage back a few feet on the wing to help balance things???

We could just throw 4-500lbs of lead ballast some where near the tail. Now what does this do to allowable G loading's in flight? even if we are in allowable total weight limits the localized increases in weights call for some structural strengthening.

You also need to figure out if you can actually turbo charge the R-2600, they few attempts I know about didn't work so well. Maybe it just needed more money????

The R-2600s need more fuel to give their extra power, what happens at cruising speed at 22-24,000ft?

DO the R-2600s suck down more fuel for the same speed? If you are comparing the turbo 1820 to the Non-turbo R-2600 this could get very close.

A B-17 could use 413 gallons an hour at 25,000ft at 172mph indicated using 900-1000hp per engine.

An R-2600 won't even give you 900hp at 25,000ft at a cruise setting.



While power and acceleration have improved with the bigger engines lift has not, has the field performance gotten better or worse? since you can not jettison the 1 1/2 to 2 tons of extra powerplant weight landing field length and stall speed has gotten worse.

 

[GrauGeist]

One of the problems you will encounter with a diesel engine at high altitudes where these bombers operate, is the fuel will congeal...