R-1830: feasible/plausible development?

[Shortround6]

True and the FM-2 was a second rate fighter.

By the time the first FM-2 came out the factory door there had been 1290 F4U-1s built and 1069 F6Fs. As valuable a service as the FM-2 provided nobody in late 1943 expected it to be the primary offensive or defensive fighter of the fleet or for shore bases in a hotly contested zone.

First FM-2s did not have 1350hp but rather 1300hp. The Wright engine was several hundred pounds lighter than the R-1830 and the Prop used on the FM-2 was designed for (biased to) short take-offs for escort carriers.

The fact that the Japanese failed to build large numbers of first rate fighters in late 1943 and 1944 does not mean that the FM-2 gets promoted to first rank by default.

 

[davebender]

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

I don't think that's true.

Air forces determine optimum operating altitude (bombing accuracy vs aircraft survivabilty). That decision becomes part of specifications for engine purchases. If the RAF had wanted Lancasters to bomb from 30,000 feet the engines would have a different supercharger or turbocharger.

 

[tomo pauk]

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.

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.

Thanks for the sets of numbers

The problem with 'Start und Notleistung' rating (1,42 ata and 2800 rpm) is that such thing is of almost no value for the bomber job - it's one minute rating IIRC. The more realistic value should be the 'Climb and combat' power setting (1,30 ata 2600 rpm), a 30-minute rating, worth some 1050 HP for the DB-605A at 7000 m (= 22600), or some 4200 HP for the He-177 with DB-610. Sure enough, if your mission is 5 hour long one...
The turbo R-1830 (historical type, for B-24s), has 'Max continuous' (= as long the fuel oil last) setting providing 1100 HP, making 4400 HP total.

 

[Shortround6]

When are the specifications written?

In 1938-40 even if the the RAF had wanted Lancasters to bomb from 30,000 feet the engines did not exist and would not exist for several more years. Please see the Wellington MK VI for a bomber that was to operate at high altitude.

The impetus for the two stage Merlin. If the early bombers don't have the two stage superchargers (or turbos) then they bomb from the altitudes they can reach. Altitude is also a function of wing area and aspect ratio. Short Stirlings having a lower altitude than Halifax's and Lancaster's with the same engines.

No matter how much money you have you cannot purchase what does not exist.

 

[davebender]

I don't think that's correct for a He-177A5 operating during 1944.

 

[Shortround6]

Thanks for the sets of numbers

The problem with 'Start und Notleistung' rating (1,42 ata and 2800 rpm) is that such thing is of almost no value for the bomber job - it's one minute rating IIRC. The more realistic value should be the 'Climb and combat' power setting (1,30 ata 2600 rpm), a 30-minute rating, worth some 1050 HP for the DB-605A at 7000 m (= 22600), or some 4200 HP for the He-177 with DB-610. Sure enough, if your mission is 5 hour long one...
The turbo R-1830 (historical type, for B-24s), has 'Max continuous' (= as long the fuel oil last) setting providing 1100 HP, making 4400 HP total.

Thank you Tomo, too many people only look at peak numbers and not the numbers at the altitudes the planes used on operations or the differences between what a loaded bomber needs to climb to altitude (even 20,000ft) and what a fighter needs.

 

[gjs238]

True and the FM-2 was a second rate fighter.

By the time the first FM-2 came out the factory door there had been 1290 F4U-1s built and 1069 F6Fs. As valuable a service as the FM-2 provided nobody in late 1943 expected it to be the primary offensive or defensive fighter of the fleet or for shore bases in a hotly contested zone.

First FM-2s did not have 1350hp but rather 1300hp. The Wright engine was several hundred pounds lighter than the R-1830 and the Prop used on the FM-2 was designed for (biased to) short take-offs for escort carriers.

The fact that the Japanese failed to build large numbers of first rate fighters in late 1943 and 1944 does not mean that the FM-2 gets promoted to first rank by default.

The point I was trying to make is that R-1820 and R-1830 powered aircraft served throughout the war, so improvements to those engines were probably justified.
Even 2nd tier fighters such as the FM-2 deserve the best engines practical.

 

[Vincenzo]

The more realistic value should be the 'Climb and combat' power setting (1,30 ata 2600 rpm), a 30-minute rating, worth some 1050 HP for the DB-605A at 7000 m (= 22600).

this is true but 7000 m are high for cruising with a DB-605A, probably get 1050 PS as max continuos flying lower

 

[Shortround6]

I don't think that's correct for a He-177A5 operating during 1944.

Why??

Kurfürst - DB 601, 603, 605 datasheets - DB 605 A

Look at the chart. It maybe PS instead of HP but where is any power going to come from at the 1.30AtA and 2600rpm limit?

 

[Shortround6]

The point I was trying to make is that R-1820 and R-1830 powered aircraft served throughout the war, so improvements to those engines were probably justified.
Even 2nd tier fighters such as the FM-2 deserve the best engines practical.

You have almost answered your own question.....best engines practical.

how much retooling at the factory (and loss of production) and how many new parts do you want to introduce into the supply chain for a 12.5% increase in take off power and a very small increase in altitude rating at the same power.

Pratt had the R-2000 available if anybody wanted it besides the C-54. near the end of the war they cut the R-4360 in half to make an R-2180. And they tried upping the R-1830 to the 1350hp level using what they had learned on the R-2800.

Wright had a power gap in their line up, jumping from the R-1820 to the R-2600. Rather than develop a new engine they spent a lot of time and money improving the R-1820 and did (post war ?) get it to 1525hp but the only thing they had in common with the 1200hp R-1820s were the cylinder lay out and the bore and stroke. Practically every part was different. It worked out for Wright because they sold a lot of them as helicopter engines post war. But at what point does a particular power increase go from being "practical" ( small change) to impractical ( big changes and butting heads with one of your own designs)

 

[davebender]

Because the data sheet you refer to is dated 1941. The engine had many improvements by 1944.

 

[Shortround6]

What were they and how did they affect power at 7000 meters?

Did the DB610 get many (or any) of the "improvements" the DB605 got?

Did the DB610 get GM 1 or MW/50?

Did the DB610 get the bigger superchargers the later DB 605s got?

Do you have any proof that the later DB610s gained power over the early ones?