davebender
1st Lieutenant
A worthwhile feature. However protecting aircrew against ground fire should have priority over protecting the engines. Otherwise you are likely to have an aircraft with good engines being flown by a dead pilot.
Do-215 B5 as a heavy fighter/strafer
Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
Shortround6
Major General
The Jumo 210 and the Bramo 323 were not really contemporaries. Bramo 323 production was starting up as Jumo 210 production was winding down or at least crossing over. The Jumo 211 and the Bramo 323 started test running within months of each other while the Jumo 210 started 3-4 years earlier. By the time the higher power, improved 323s show up the Jumo 210 is out of production, prototypes used them, in some case, not because they were really the intended engine but because they were available.
In the case of the Fw 187 I don't know how many left over Jumo 210s (unused form store or referbed) but the Bramo is not an attractive engine to use on it. I used the Allison vs P&W because it is a good example, the Curtiss airframe was used at least 6 different major engine set ups (3 different radials, Allison both turbo and not and Merlin) so it can show differences between powerplants with airframe differences showing up, at least not to any large extent. Yes there can be differences on other airframes or installations.
And go back to the early Do 17s. The BMW VII didn't use exhaust thrust and it was faster (slightly) than the Bramo powered version that had 20% more power. It was even supposed to be faster than the BMW 132 powered recon version that had 33% more power. The BMW version had 1000hp for take-off? I don't know what power levels they were using for sea level flight. Perhaps they had to cut back from take-off power. the point is that a lot of the extra power goes into fighting the extra drag.
Maybe you will wind a bit faster but not by a lot. The FW 187 was supposed to do 322mph at sea level with the Jumo 210 engines. Comparison withe Grumman Xf5F-1 is interesting, The Grumman was flown with the big Cyclones in order to have a plane to test, the original 2 stage R-1535 engines and been dropped from development by P W and it is quite possible that trying to use two stage R-1830 engines would have required too much modification as they are several hundered pounds heavier (each) than the planned engines or the Cyclones.
The data sheet on the XF5F-1 is supposed to be the results of test flights and while it did make 358mph at 17,300ft it was because of the altitude capability of the engines. Speed at sea level is given as 312mph and 326 at 4500ft and 324 at 7300ft.
The data sheet is not 100% clear and these speeds may be at the "normal" rating of 1000hp instead of the take-off rating of 1200hp ( 2300rpm instead of 2500rpm)no military power is listed on the data sheet. If we assume the power used was the "normal" rating (max continuous) it means the XF5F-1 was slower at sea level using 1000hp per engine than the Fw 187 was using 700hp per engine. Now the Skyrocket could very well have had some other problems that added to the drag, they never did get the landing gear doors to fit/retract correctly. That canopy may have offered great vision but may have contributed to drag. There may have been other airframe issues (wing to fuselage fairing?) so it is not fair to blame the entire difference on just the engines. The Jumo's were getting some benefit from exhaust thrust however.
As far as the Jumo powered Ju 87 s go, there were about 200 built and they all had been sent to flying schools by the time the shooting started. Given that Jumo 211 powered versions started leaving the factory/s in the summer of 1938 and alsmot as many 211 powered planes had been completed by the end of 1938 as 210 powered planes it makes no difference to the Luftwaffe if the first 200 planes had Jumos 210s or radial engines.
The big 9 cylinder radials worked fine on airliners, cargo planes and early bombers like Wellingtons, they weren't so good on planes with low drag airframes where the engines became a larger part of the drag picture.
In the case of the Fw 187 I don't know how many left over Jumo 210s (unused form store or referbed) but the Bramo is not an attractive engine to use on it. I used the Allison vs P&W because it is a good example, the Curtiss airframe was used at least 6 different major engine set ups (3 different radials, Allison both turbo and not and Merlin) so it can show differences between powerplants with airframe differences showing up, at least not to any large extent. Yes there can be differences on other airframes or installations.
And go back to the early Do 17s. The BMW VII didn't use exhaust thrust and it was faster (slightly) than the Bramo powered version that had 20% more power. It was even supposed to be faster than the BMW 132 powered recon version that had 33% more power. The BMW version had 1000hp for take-off? I don't know what power levels they were using for sea level flight. Perhaps they had to cut back from take-off power. the point is that a lot of the extra power goes into fighting the extra drag.
Maybe you will wind a bit faster but not by a lot. The FW 187 was supposed to do 322mph at sea level with the Jumo 210 engines. Comparison withe Grumman Xf5F-1 is interesting, The Grumman was flown with the big Cyclones in order to have a plane to test, the original 2 stage R-1535 engines and been dropped from development by P W and it is quite possible that trying to use two stage R-1830 engines would have required too much modification as they are several hundered pounds heavier (each) than the planned engines or the Cyclones.
The data sheet on the XF5F-1 is supposed to be the results of test flights and while it did make 358mph at 17,300ft it was because of the altitude capability of the engines. Speed at sea level is given as 312mph and 326 at 4500ft and 324 at 7300ft.
The data sheet is not 100% clear and these speeds may be at the "normal" rating of 1000hp instead of the take-off rating of 1200hp ( 2300rpm instead of 2500rpm)no military power is listed on the data sheet. If we assume the power used was the "normal" rating (max continuous) it means the XF5F-1 was slower at sea level using 1000hp per engine than the Fw 187 was using 700hp per engine. Now the Skyrocket could very well have had some other problems that added to the drag, they never did get the landing gear doors to fit/retract correctly. That canopy may have offered great vision but may have contributed to drag. There may have been other airframe issues (wing to fuselage fairing?) so it is not fair to blame the entire difference on just the engines. The Jumo's were getting some benefit from exhaust thrust however.
As far as the Jumo powered Ju 87 s go, there were about 200 built and they all had been sent to flying schools by the time the shooting started. Given that Jumo 211 powered versions started leaving the factory/s in the summer of 1938 and alsmot as many 211 powered planes had been completed by the end of 1938 as 210 powered planes it makes no difference to the Luftwaffe if the first 200 planes had Jumos 210s or radial engines.
The big 9 cylinder radials worked fine on airliners, cargo planes and early bombers like Wellingtons, they weren't so good on planes with low drag airframes where the engines became a larger part of the drag picture.
This might decipher a bit the Bramo saga. The table is from the book about the Do-17/215.
Some caveats, though.
-for the 323J and M, the term '2-Gang-Bodenlader' is clearly a major typo - nobody was making 2-speed supercharger gearing with both speeds tailored for low level flight. Only one S/C gear is listed (11,4 for the 323J; in US parlance it would've been 11.4:1), and that means it is 1-speed, hi-alt version. As such is also stated by Von Gersdorff et al in their book. For the 323M, the prop reduction gear is listed at 9,52, but that would be the S/C gearing - makes it a low level engine, 1-speed S/C; again, as such is stated by Von Gersdorff et al.
-it is very much posible the 323R/2 was the version 'tailored' for C3 fuel (unlike the 'plain' 323R), hopefully someone will set me straight on this
I've tried to use underlining of same color to leave the table as clear as possible, yet to be reasonably understandable. Please open it separately for high resolution.
Some caveats, though.
-for the 323J and M, the term '2-Gang-Bodenlader' is clearly a major typo - nobody was making 2-speed supercharger gearing with both speeds tailored for low level flight. Only one S/C gear is listed (11,4 for the 323J; in US parlance it would've been 11.4:1), and that means it is 1-speed, hi-alt version. As such is also stated by Von Gersdorff et al in their book. For the 323M, the prop reduction gear is listed at 9,52, but that would be the S/C gearing - makes it a low level engine, 1-speed S/C; again, as such is stated by Von Gersdorff et al.
-it is very much posible the 323R/2 was the version 'tailored' for C3 fuel (unlike the 'plain' 323R), hopefully someone will set me straight on this
I've tried to use underlining of same color to leave the table as clear as possible, yet to be reasonably understandable. Please open it separately for high resolution.
Last edited:
Shortround6
Major General
The reprint of the 1946/47 'Jane's' (not a primary source) gives the same Supercharger gear ratios and prop gear reductions even if they don't have the same number of models listed.
It does list max pressure with the 11.4:1 supercharger gear as 1.45 ata for take-off and emergency at 2500rpm and 1.53 ata for the 9.52:1 supercharger at 2500rpm.
The P,R and T engines are listed at 1.5ata at 2500rpm and the R-2 at 1200hp for take-off at 2600rpm and 1.63ata with the methanol/water.
It does list max pressure with the 11.4:1 supercharger gear as 1.45 ata for take-off and emergency at 2500rpm and 1.53 ata for the 9.52:1 supercharger at 2500rpm.
The P,R and T engines are listed at 1.5ata at 2500rpm and the R-2 at 1200hp for take-off at 2600rpm and 1.63ata with the methanol/water.
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
They tried the WB81Z pods slung underwing on the Ju87 and it wasn't a very successful venture.
kool kitty89
Senior Master Sergeant
Yes, but air superiority doesn't mean there's no need for escorts or ability to evade interception, including said evasion buying time and making escorts more effective.
Additionally, P-40s and Hurricanes used as fighter-bombers also needed escorts to be effective.
Indeed, pilot armor and fuel protection is very necessary as well and can't be ignored. Likewise, the Hs 129 itself (already very heavily armored) could have fared better with Bramo or 14N radials in both takeoff/speed/climb and single-engine performance (which was virtually unusable on the 14M -totally useless on the originally planned As 411).
Indeed, the 323, 211, and DB 600/601 were all contemporaries and all in the same power class initially, but when the likes of the Jumo 210 (sometimes Bmw 132) were being substituted due to shortages of DB 600s and 211s, while the late 30s 323s seem like they would be more attractive alternatives in at least some situations. (Bf 110 and Ju 87 more so than Fw 187, and purely speaking of the early A/B and C/D models)
This of course assumes the 323 was also not suffering shortages around the same time as the DB 600 and Jumo 211A.
At very low level, I'm not surprised the BMW V12 powered models were a bit faster (lower weight to consider too), but I have a hard time believing that was true at altitude. (given we're not talking about the 850 HP supercharged BMW XI -I think Kawasaki even implemented ejector exhausts on in the late 1930s)
The Russians and Japanese took more interest in supercharged BMW VI/VII/IX derivatives, but I'm not sure what the situation was like in Germany. (otherwise that may have been a more attractive alternative than either the Jumo 210 or radial engines for some applications)
From the discussions where that claim came up, it seems 'sea level' and 'low level' were confused and in fact the 322 MPH figure was for the crit alt of the 210G in low gear, which makes much more sense given the 329 mph figure for high gear (and the Bf 109C's performance on the same engine -or D on the slightly lesser 210D)
322 mph at SL would have been fantastic at the time, and significantly faster than any fighter in service in 1940, including the 109E. It's likely closer to what the 187 would have managed on DB 601As.
That said, the Fw 187A-0 was supposed to be as fast or slightly faster than the Spitfire and 109E below 10,000 ft. (without WEP) Climb rate advantage was bigger.
Perhaps also useful as a performance boost on Finnish B-239s with the 2-speed Bramos replacing the lower powered Cyclone engines, though I'm not sure how similar the mounts were.
Shortround6
Major General
The BMW V-12 was little more than two WW I straight sixes on a common crankshaft and was most definitely behind the other engines. It gave the Luftwaffe it's start. It was a 47 liter engine that weighed 1100lbs and ran at rather low RPM and was unsupercharged until the IX model. It wasn't a contender and that is why the Germans were working on so many new engines. BMW actually built the BMW 116 inverted V-12 in the same class as the Jumo 210 and Kestrel but it saw no use. Point in bring it up was, once more, to try to show the big difference in drag the radials had. You are going to use up several hundred of the extra HP just fighting the drag of the radial if the goal is speed.
My Mistake, I quoted Green. Figures may be 289mph at sea level and 319mph at 1900 (6270ft) meters. FW engineers figured exhaust thrust was good for a 13% boost in power but that may be an average or best case ?
Unless you use water/methanol injection the Bramo had no more power than the Cyclone. The Finns used the R-1820-G5 engine which was good for 1000hp for take-off. "normal" rating (which is max continuous rich) was 850hp at both sea level and 6000ft in low gear and 750hp at 15,200ft (4640 meters), Normal rating was at 100rpm less than take-off. AHT claims the engines used in the Finnish aircraft were good for 800hp at 16,000ft "military power" at 2200rpm instead of the 2100rpm Max Continuous. The Finnish engines were supposed to have two speed superchargers according to American accounts.
Found a textfile on my drive with Bramo 323 subtypes:
Fw 200C-3 Kennblatt states it's equipped with Bramo 323R-2 with 1000PS at 2500rpm and 1.5 ata (1100PS with 100 Oktan fuel (AKA C-3)).
Code:
Var Fuel System Supercharger Type ... Drive T/O HP Reduction
A High altitude engine 11.4 900 0.62
J Carburettor High altitude engine 11.4 900 0.62?
B High altitude engine 11.4 900 0.71
Q High altitude engine 11.4 900 0.71?
M Carburettor Low altitude engine 9.52 1000 0.62
D Low altitude engine 9.52 1000 0.62
C Low altitude engine 9.52 1000 0.71
T Low altitude engine 9.52 1000 0.71?
P Two-speed supercharger 9.6/12.4 1000 0.62
N Two-speed supercharger 9.6/12.4 1200 0.62? MW injection
S Two-speed supercharger 9.6/12.4 1000 0.71?
R Two-speed supercharger 9.6/12.4 1200 0.71? MW injectionFw 200C-3 Kennblatt states it's equipped with Bramo 323R-2 with 1000PS at 2500rpm and 1.5 ata (1100PS with 100 Oktan fuel (AKA C-3)).
BMW also worked on the BMW 117, a 36L engine. It was developed between 1934 and '36, being cancelled (along with the 116) in winter of 1936/37 by the RLM decree that specified that BMW would concentrate on radial engines. The BMW 117 and 116 dispensed with individual cylinders of legacy inlines, featured the 1-speed S/C, CR was 6.5:1. The 117 was supposed to make 1100 PS on take off at 2580 rpm, rated height was at 3800 m, weight 525 kg, fuel injection.
Potentially a better engine than Jumo 211 or DB 600 series, though the weight is a bit on the light side? More worthwhile to push forward than with BMW 139/801?
edit: the DB 600 started from 540 kg, for TO power of 1000 ps at 2400 rpm.
On the Bramo 323: If I understand this correctly, the installation of fuel injection begun with J and N versions? Von Ghersdorff et al saying that J and M were 'outfitted with carbs initially' when exhibited in Paris in 1938.
The 30 min power of the 323P was 820 PS in 1st gear. How much in 2nd gear, 700 PS? Sure enough, the engine will need to be rated for 5 min rating, that again might bring the power to maybe 750-800 PS in second gear?
The Bramo 323 featured the 'single handle' powerplant control, that came to fame with BMW 801.
Last edited:
One of the uses of the BMW 323 R/2 was the Ju 352 Herkules. That aircraft generally ran of 87 octane "B4" fuel but could used 96/125 "C3" to increase boost during take-off before optionally switching back to the B4 fuel supply. The table you provided says "ausfuring" which means issue: that to me means it could be issued as a C3 version.
So, in order to gain power through increase boost there were two alternatives either B4+MW50 before reversion to B4 only or C3 before reversion to B4. Obviously one could run of C3 all the time but that defeated the purpose of reserving this precious fuel for critical areas only.
It seems a good solution: a separate C3 tank is probably less inconvenient than a MW50 tank, furthermore it can be used as an emergency reserve fuel supply and factored into range calculations. Methanol for MW50 itself could be in short supply as it too came from a refinery. MW50 was injected at a rate equal to the B4 rate but I imagine C3 alone would be injected in at a rich mixture about 25%
Shortround6
Major General
The Bristol Blenheim used a similar arrangement. outer tanks with 100 octane and inner tanks with 87 octane. the 100 octane being reserved for take-off and combat. The higher octane fuels do not have to be injected at significantly higher rates unless you are going for the last few percent of performance and are using the excess fuel as a coolant. You do have to keep the air/fuel mixture rate the same and allow for fuel flow to match the higher boost/airflow. Trying to mix the fuels ,ie, 75% 87 octane and 25% 100 octane is going to give you something like 91-92 octane fuel, assuming you get a good mixture in the intake manifold and not 89 octane going to a few cylinders and 95 octane going to others.
How effective this trick is depends a lot on the engine. It was very effective on the Mercury XV engine and much less effective on the Pegasus.
How well this trick works on 30 minute (climb) is another question and it doesn't work at all on cruise.
How effective this trick is depends a lot on the engine. It was very effective on the Mercury XV engine and much less effective on the Pegasus.
How well this trick works on 30 minute (climb) is another question and it doesn't work at all on cruise.
kool kitty89
Senior Master Sergeant
Wouldn't any C3 applicable Bramo engine also be using direct fuel injection?
Shortround6
Major General
It should. The BMW 801 (or one model of it) also injected fuel into the air intake in front of the supercharger, this was over and above the fuel needed for combustion and acted as a charge coolant much like MW/50. AS the fuel went through the supercharger and the heating of the supercharger the fuel vaporized and it is this heat of vaporization that cools the charge (R-R figured they got about 25 degrees C of cooling from the fuel vaporization on a single stage Merlin).
Koopernic had stated " MW50 was injected at a rate equal to the B4 rate but I imagine C3 alone would be injected in at a rich mixture about 25%"
MW 50 was injected into the eye of the supercharger, not direct injected into the cylinders.
On the BMW the system injected 14.3 gallons (imp) per hour into the air intake. this allowed the boost pressure to go from 5.5lbs to 8.8lbs. Total fuel flow went from 146 imp gal an hour to about 185 Imp gal an hour.
I am getting the figures from the 1946 Jane's reprint and so this is a British evaluation of captured equipment. German documents/sources may differ.
If you spray fuel into the intake before the supercharger you are subject to the same distribution problems carburetor equipped aircraft had even if the bulk of the fuel is direct injected.
