R-1830: feasible/plausible development?

[tomo pauk]

Hi,

The P&W R-1830 Twin Wasp was one of the most used radial engines in the ww2. In different installations it was powering fighters, bombers, patrol planes, transports etc.
One thing that seem illogical is an almost non-existing increase in power - 1200 hp was mostly there from 1940 until 1945. Wonder if there were any attempts to boost that figure, and where such attempts would be mostly felt?

 

[wuzak]

R-2000?

 

[davebender]

I don't think you will get much more then 1,200 reliable hp from an air cooled engine with a displacement of only 30 liters.

 

[Shortround6]

A few versions were rated at 1350hp for take-off.

No engine company had unlimited engineering staff. Projects needed to have a decent pay-off in order to be under taken. In order for the R-1830 to make much more power it would need a number of the "tricks" used on the P&W R-2800, unfortunately incorporating some of those 'tricks' might call for some major retooling of the factories. Changing from cast to forged cylinder heads. Changing from plain steel cylinder barrels ( one piece) to a steel liner and aluminium fin cooling muff ( 2 piece) It may require larger or more cylinder hold done bolts. And so on.

It could have been done but to what purpose? You would also be trading power for engine life. many of those transports and patrol aircraft went through multiple engine changes, some civilian DC-3s had gone through a dozen sets of engines even before the war broke out.

 

[wuzak]

It could have been done but to what purpose? You would also be trading power for engine life. many of those transports and patrol aircraft went through multiple engine changes, some civilian DC-3s had gone through a dozen sets of engines even before the war broke out.

I would think that extra power could have been handy for the B-24.

 

[davebender]

Wouldn't it be less trouble and more effective to install R2600 engines on a heavy bomber?

The only reason I can see for continued development of the R1830 engine would be continued development of the P-36 fighter aircraft. The larger and heavier R2600 engine won't fit on such a lightweight fighter aircraft.

 

[Shortround6]

Depending on the source some of the late B-24s got the 1350hp version as did the P4Y-2 Privateer. They did use a different supercharger (?) and fin and cooling muff arrangement. They may have been made by Buick only (?).

 

[wuzak]

Wouldn't it be less trouble and more effective to install R2600 engines on a heavy bomber?

The only reason I can see for continued development of the R1830 engine would be continued development of the P-36 fighter aircraft. The larger and heavier R2600 engine won't fit on such a lightweight fighter aircraft.

I would think that production override any thoughts of such a change.

Production of both the R-1830 and the B-24.

The R-2600 weighed some 66% more than the R-1830, for about 50% more power. It was also physically larger - 55" (1397mm) diameter vs 48" (1219mm), although only 3" (76mm) longer. The extra weight and size would require a lot of extra engineering.

The R-2000 was a derivative of the R-1830 with a bigger bore. It would fit in much the same space as the R-1830, and weight would hardly change. Increasing production shouldn't be a problem - replace an R-1830 for an R-2000. Not so easy for the R-2600. Power increase would be modest - 100-200hp at best.

You may ask if that was teh best course why wasn't the B-17 converted? The R-1820 was the same diameter as the R-2600, albeit shorter and lighter.

 

[gjs238]

The only reason I can see for continued development of the R1830 engine would be continued development of the P-36 fighter aircraft. The larger and heavier R2600 engine won't fit on such a lightweight fighter aircraft.

Or the F4F.

 

[Shortround6]

The 1350hp engines were a bit late in timing. The first B-24 to get them seems to be the XB-24K which first flew on Aug 1943. A 1350hp R-1830 powered fighter would be distinctly second rate in fall of 1943 let alone any later.

Mr Bender keeps confusing light weight prewar planes with combat capable planes of 1941-42. 3 reasons the P-36 was light weight. 1, no armor. 2, no self sealing tanks, 3, crap for armament.

Take a P-36 and add 93lbs of armor/BP glass, change the 171lb unprotected fuel tanks to 425lbs worth of protected tanks. Change the 99lbs of guns to just 314lbs ( four .50 cal), change the 96lb or so of ammo to 282lbs ( 235rpg ? of .50 cal) and see how "light" the P-36 stays. Of course adding 748lbs to a 5,650 lb plane means that it's ultimate "G" loading of 12 has dropped to 10.6 with a service "G" loading of 7 instead of 8 calling for some structural reinforcement if the plane is to meet USAAC requirements.

The 5,650lb weight is with the 3rd fuel tank ( overload tank) empty. P-36s also had trouble with wing skin wrinkling/buckling in service which required a bit of reinforcing.

A nice plane but let's not pretend is something it wasn't.

 

[davebender]

R1830 engine.
1,200 hp.
1,250 lbs Dry weight.

R2000-3 engine.
1,350 hp.
1,570 lbs. Dry weight.

R2600 engine.
1,600 hp. Early models. Later models up to 1,900 hp.
2,045 lbs. Dry weight.
The R2600 was in mass production during 1940.

 

[Shortround6]

R1830 engine.
1,200 hp.
1,250 lbs Dry weight.

I have no idea where you are getting that weight from but it is way off. 1250lbs is about right for some of the earlier 830-1000hp commercial versions. The 1200hp versions were over 1400lbs and ones with two speed ( not two stage) superchargers went around 1450-1490lbs depending on propeller gear ratio, carburetor and magneto type.

R2000-3 engine.
1,350 hp.
1,570 lbs. Dry weight.

Correct

R2600 engine.
1,600 hp. Early models. Later models up to 1,900 hp.
2,045 lbs. Dry weight.
The R2600 was in mass production during 1940.

we have gone over this a number of times.

The MASS production 1940 model was 1600hp. it went about 1950lbs, mass production means 1925 produced during the year with 1165 of those produced in the last 4 months.
The 1700hp version shows up in 1941 with 443 built. 341 in the last 2 months of the year. They are built in a brand new factory and use a different crankcase than the 1600hp engines. These go about 1980lbs.
The 1900hp version doesn't show up in production until 1943 with with 1002 built, 863 of them in the last 3 months of the year. This is the 2045lb version. It also uses different cylinder finning, different cylinder heads and perhaps a modified crankcase.
There were definite modifications for each power level and an older model engine cannot be operated at higher power levels by dumping higher performance number fuel in the tank and fiddling with the boost control. Each major modification required at least some new tooling in the plant. By some I mean changinf from aluminium casting and forging to steel casting and forging for the Crankcase. 1900hp versions required a completely new way of making cylinder fins.

 

[tomo pauk]

The 1350hp engines were a bit late in timing. The first B-24 to get them seems to be the XB-24K which first flew on Aug 1943. A 1350hp R-1830 powered fighter would be distinctly second rate in fall of 1943 let alone any later.

-snip-

A B-24 with 4 x 1350 HP (for take off?) in 1944 seem like a decent bomber. Any info about how high (if?) the max continuous power was increased?

 

[davebender]

4 x 1,350 = 5,400 total hp. That would be ok for a heavy bomber during 1942. IMO it's underpowered for a heavy bomber during 1944.

Lancaster III.
4 x RR Merlin 224 (built by Packard).
1,640 hp each = 6,560 hp total.

He-177 A5.
2 x DB 610 coupled engines.
2,900 hp each = 5,800 hp total. Plus aerodynamic benefits from using coupled engines.

 

[tomo pauk]

5400 HP seem like a better bet than 4800
As for the comparison with another bombers/engines, we need to compare take-off power, max continuous (at cruising altitude), even the 15-30 min rating. Those 5400 HP should be there at 25000 ft, too.

 

[Shortround6]

Aside from the XB-24K the use in the B-24N is late and very small, most were canceled at the end of the war, the 5400hp was supposed to available at 30,000ft.

Normal ratings were about the same as the 1200hp versions but gained 2-800ft of altitude.

The non-turbo 1350hp models seem to be used in late Privateers and in some transport versions. The engine may not be available in quantity until late 1944 at which point it is almost an answer in search of a question.

 

[davebender]

I disagree.

What counts is power at the altitude where the bomber normally operates. For the Lancaster that would be around 20,000 feet.

 

[Shortround6]

For a bomber that had four of the 1350hp R-1830s with turbos, it would have had 5400hp from about 6-7,000 ft all the way up to and beyond 25,000ft in Military power. The Lancaster may have 6540hp for take off and a bit more at 2500ft but by 9800ft power is down to 6040-6180hp ( critical height at 18lbs boost) with power dropping at roughly 2.2% per 1000ft.

If the DB 610 in the He 177 follows the same power curve as the DB 605A with 1.42 Ata and 2800 rpm it should have about 4300PS at just under 25,000ft. Perhaps 4800PS or just a bit less at 6500meters (21,500ft) or just about what a B-17 or B-24 had with their 1200hp engines.

 

[wuzak]

I disagree.

What counts is power at the altitude where the bomber normally operates. For the Lancaster that would be around 20,000 feet.

The problem with that is that aircraft like the Lancaster operated at heights which their capabilities allowed them (ceiling for Lanc is about 22,000ft IIRC), not necessarily the altitude that they might have wanted.

 

[gjs238]

The 1350hp engines were a bit late in timing. <SNIP> A 1350hp R-1830 powered fighter would be distinctly second rate in fall of 1943 let alone any later.

If Wikipedia is accurate, the FM-2 had the 1,350 hp (1,010 kW) Wright R-1820-56.