Fw 190: the good, the bad and the ugly (1 Viewer)

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It was easier that way?


Look here, it is 2700 rpm for the Jumo 211R. Problem with the 211R is that it was too late to matter - every 211 built in 1944 means one 213 less.
 
Look here, it is 2700 rpm for the Jumo 211R. Problem with the 211R is that it was too late to matter - every 211 built in 1944 means one 213 less.
The other suggestion (of putting emphasis on a higher altitude rated 211 sooner -at the expense of low altitude performance) still stands. If the 211R used a 2-stage supercharger arrangement similar to the 213A, that would be less directly applicable to potential earlier developments, but if it was closer to the single-stage unit of the F/J/N/P (or identical to it, but using higher gear ratios) then that indicates such developments should have been feasible to introduce considerably sooner. (doing so in parallel with the 211J's intercooler development seems attractive given the greater needs for charge cooling with higher supercharger compression ratios)
 
Yes and no, the inter-coolers create drag, and the more you compress the air, say for high altitude work, the hotter it gets and the more airflow (drag) you need to cool the intake air. Now at high altitude where the air is thin the extra power more than offsets the extra drag and the plane will be faster. At lower altitudes the drag trumps the extra power and the plane is slower.
it is not the manifold pressure that counts here (1.42 Ata or whatever) but the amount of compression needed to get the outside air to 1.42 Ata (or whatever manifold pressure you are looking for).
 
If using an intercooler closer to (or the same) size of that of the 211J, wouldn't it be possible to increase the supercharger speed (or use a larger/different supercharger) and end up with acceptable charge densities and temperatures? (perhaps close to the 211F's but with higher critical altitudes)
 

The 213A was using 1-stage S/C, not two stage S/C. The 2-stage unit was introduced with Jumo 213E.

Jumo 211J (= intercooled), with 'faster' S/C should've been a decent 'fighter engine'. The engine + intercooler will have a bit less drag than even the tightly cowled BMW 801, plus there is a weight save and less consumption. Weapon drag will be also smaller for same firepower, assuming prop cannon is installed instead of cowl HMGs. Use of C3 fuel will mean also plenty of power at low and medium altitudes, though the engine needs to be tested rated for that in the 1st place.

With that said, the intercooled DB 601/605 engines would be also interesting choices for the Fw 190.
 
The Jumo 211J was the ONLY single stage engine that was mass produced and fitted with an intercooler and it was used on bombers. The general thinking of the time was that the benefit of using an intercooler on a single stage engine engine in a fighter wasn't worth the weight and bulk/drag. The engine installation in a fighter being a much larger fraction of the total drag than the engine installation/s on a bomber. We may be able to find the weight of the intercooler on the 211J but you are aiming at a moving target. Running the supercharger faster and compressing the air more for better altitude performance is going to heat the intake charge more and require a larger inter-cooler and and higher mass flow of cooling air than the "J" needed.
 
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The engine installation in a fighter being a much larger fraction of the total drag than the engine installation/s on a bomber.

It was the other way around - powerplant drag of 2-engined aircraft represented a bigger percentage of the total drag than on the 1-engined A/C in ww2. Eg. - Welkin started with powerplant drag being 19.4% of total drag, the Beaufighter was at 35.4%, Mossie and Whirly being in between. Spitfire was at 16.5-18 (Merlin 45) and at 19% (2-stage Merlin); British calculated the Fw 190 with 21.5%. Per tables kindly provided by Neil Stirling a short while ago.
We may be able to find the weight of the intercooler on the 211J but you are aiming at a moving target.

The intercooler was also a radiator - ie. it is of air-to-air type. The weight should be pretty low? The compressed air exited through the tube (42a), entered the intercooler and exited it, to enter the tube 44a:



Running the supercharger faster and compressing the air more for better altitude performance is going to heat the intake charge more and require a larger inter-cooler and and higher mass flow of cooling air than the "J" needed.

The fighter with the Jumo 211J will fly faster than the Ju 88 with the same engine - 100 km/h faster on same settings, or 25% faster, for 25% more air flow?
 
The 213A was using 1-stage S/C, not two stage S/C. The 2-stage unit was introduced with Jumo 213E.
Was that single-stage Jumo 213 still used the swirl type inlet/throttle guide vanes, right? Was it also intercooled?

The engine + intercooler will have a bit less drag than even the tightly cowled BMW 801, plus there is a weight save and less consumption. Weapon drag will be also smaller for same firepower, assuming prop cannon is installed instead of cowl HMGs.
Similar or better fire with the hub cannon, yes. (either an MG 151/20 or MK 108 should be more destructive than the pair of MG 131s, let alone preceding MG 17s). Drag might be a better than Jumo's standard annular radiator with a more streamlined one adapted specific to the 190 airframe. (plus, moving the radiator further aft, below the engine or fuselage should give better control over CoG while still keeping coolant lines and intercooler ducting short)

With that said, the intercooled DB 601/605 engines would be also interesting choices for the Fw 190.
Sticking with the existing 211F and J as the basis might have advantages in reliability over the 605 too. (DB 601 with intercooled DB 603 supercharger would have been interesting, intercooled DB-605AS certainly too though again there's the bearing lubrication issues)

Come to think of it, I don't recall any mention of the DB 603 suffering from bearing issues. Had it avoided use of roller bearings from the start and incorporated more satisfactory alternatives than the DB 605? (or at least compared to the initial production DB 605) If that was the case, might it have made more sense to forgo DB-605 production altogether in favor of more DB 603s as DB-601 production wound down?


For that matter, the 211J entered production ad service much earlier than the 605AM or D, and if tested/rated for higher boost with C2/C3 fuel, should have outstripped the 605A's performance without water injection, or possibly even approach the 605AM's at critical altitude.



Weight would be a bigger consideration on a single engine fighter (cockpit/pilot/armor, fuel tankage, and engine weight would all be bigger considerations on a single engine fighter). And unless you use a push/pull arrangement, the twin engine examples have the full engine nacelles adding to drag rather than the engine sharing some of its drag with the fuselage.

You'd need a very large wing and fuselage (and gun/turret bulges, external racks, etc) to skew that. (might have been the case for typical Ju 88 production models)

The intercooler was also a radiator - ie. it is of air-to-air type. The weight should be pretty low? The compressed air exited through the tube (42a), entered the intercooler and exited it, to enter the tube 4
From what I recall, the 211J intercoolers were also still fairly compact, fitting into an annular radiator cowling of the same diameter as the 211F but filling in some holes/gaps present between the coolant radiators.
 
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I said "bomber" not fighter
The chart doesn't list much in the way of twin engine bombers and the size of the airframe can make a difference in the percentage the engine installation takes up. The Beaufighter's engines contributing 35.4% of the drag but essentially the same engines on a Lerwick flying boat (admittedly a huge airframe) are only 14.2% of the total drag. If you make the rest of the airframe ugly enough you can get even a rather dodgy engine installation to look good number wise.



engine was only 12.3% of the total drag, much better than a Spitfire

I probably phrased it wrong. Each engine on a multi engine aircraft is a smaller percentage of the total. ie, each engine on a Mosquito is 12-14% of the total and each Merlin on a Lancaster I is about 6% of the total drag. A bomber could use certain features in engine installations that wouldn't hurt the performance anywhere near as much as the same feature on a a single engine fighter.

Granted the JU-88 was a lot smaller than a Lerwick but but there was still a lot of airframe compared to a single engine fighter.


The intercooler was also a radiator - ie. it is of air-to-air type. The weight should be pretty low? The compressed air exited through the tube (42a), entered the intercooler and exited it, to enter the tube 44a:

Thank you for the pictures.

The fighter with the Jumo 211J will fly faster than the Ju 88 with the same engine - 100 km/h faster on same settings, or 25% faster, for 25% more air flow?

and now we get into dynamics. Yes the higher airspeed gives higher airflow. However we have not just the increase in frontal area ( the easy part) but the drag of the airflow though the ducts and the inter cooler matrix. Increase the velocity of the airflow by 25% and you increase the drag by 56% even at the same mass flow. Since you increased the mass flow by 25% you may now have 90-95% more drag than the bomber had in it's inter-cooler set-up unless you change something? Like increase the area of the matrix and duct cross section to lower the velocity of the air as it goes through the inter cooler matrix?)

To get a 40% efficient inter-cooler (lowers the intake charge temperature by 40 degrees for every 100 degrees of starting temperature or every 100 degrees added to the ambient temp by the supercharger) you need a mass flow equal to the charge flow, cooling air equals combustion air. 1.5 times the combustion air can get you a bit over 50% efficiency and twice the mass flow of the combustion air can get you a bit over 60%.

It is not quite bolt the power egg from a JU-88 on the nose of a FW 190, change to fighter reduction gear ratio and prop and away you go.

Say you pick up 100hp at the prop but the inter-cooler is costing you 50hp in drag, is it worth it?
 
Say you pick up 100hp at the prop but the inter-cooler is costing you 50hp in drag, is it worth it?
Even assuming those figures stayed static (given whatever radiator configuration employed), there's still the question of: is it worth it relative to what alternative?

If either case is superior to the drag situation of the BMW 801 while also weighing significantly less, then it becomes more of a competition between the 211F and 211J (or similar engines with supercharger gearing increased for higher altitudes -if only modestly so). And then the question of what happens when more weight is added to the airframe and the added drag of the intercooler becomes less significant relative to the power gained? (ie a heavily loaded fighter-bomber or -in the more altitude optimized case- heavily armed and armored bomber interceptor)

Also consider the weight and drag related to the intercooler vs weight, drag, and fuel consumption/displacement of a (hypothetical) rich mixed or MW/50 injection system, assuming such could even be fielded on the 211F at the time the 211J became available. Then consider weight impacting drag/range and climb performance.
 
With the Jumo 211J the addition of Rich mixture or MW/50 isn't going to get you much. You are already cooling the intake charge and extra cooling isn't going to get anywhere near the increase in power. Some American planes used both inter-coolers and water injection but then they were compressing the air a heck of a lot more to begin with. A late model P-47 could pull 72in (2.4Ata) at 30,000ft in level flight (with RAM) and was compressing the air 8 times over the ambient air pressure. It was also exceeding the capacity of it's intercooler/s which had not be designed for that air flow (40% more than an early P-47).
Early American turbo practice (before WER settings) was to lower the intake air temperature back down after the turbo to 100 degrees F max at the carb intake and 90 degrees ideally. If your inter cooler on the Jumo 211 is doing it's job to begin with the intake air in the manifolds should be around a similar temperature. injecting water or extra fuel into even 100-150 degree air doesn't get you the same sort of cooling that injecting it into 200 degree+ air does.

The intercooler on the 211J may have been there as much for climb performance on the bomber as it was for speed. You are trying to get a 26-31,000lb bomber up to operating height and or improve ceiling as much as add 10-15mph to the speed. Water injection or rich mixture don't work well for long, hard climbs, you use up more Lbs of material (water or fuel) than the intercooler weighs. It could take a JU-88A-4 23 minutes to hit just under 18,000ft while weighing 27,557lbs. max take-off was 30,865lbs. The inter-cooler allowed operation at higher power levels for long periods of time and the shorter climb to altitued vs a non interecooled engine allowed for greater range on the same fuel. On a fighter it is different, the climb is much shorter only 1/3 or less of the time to get to the same altitude.
 
Was that single-stage Jumo 213 still used the swirl type inlet/throttle guide vanes, right? Was it also intercooled?

1 - yes (link), 2 - no.

The standard DB 601E was producing as much power as the intercooled 211J, so it would still be my preference to intercool the DB. We can recall that Ta 154 crashed 3 times due the engine troubles, so it would be prudent not to claim that Jumo 211 was more reliable than DB 605A, that produced more power on 30 min rating than the Jumo 211J on 1 min rating (!).
Intercooled DB 605A or 605AS would be fine engines.

(plus, moving the radiator further aft, below the engine or fuselage should give better control over CoG while still keeping coolant lines and intercooler ducting short)

Radiator under fuselage - no-no IMO, it will be a speed brake. The CoG issues should be close to non-existant with the annular radiator, the Jumo 211 engines were much lighter than the Jumo 213 or DB 603A (and one of Fw 190s flew with DB 603 and without tail 'plug').


It all depends on how long it would it take for the DB to sort out the 603A, and how good supercharger set-up is installed on the DB 601(E), plus whether it would be easy to rev-up the 601E to 2800 rpm, like the 605 managed eventually.

As above - methinks that the DB 601E 605A would need less fiddling with, in order to achieve a bit better performance. Probably, the engine that 1st is to get a workable 2-stage S/C is the 'winner'.

From what I recall, the 211J intercoolers were also still fairly compact, fitting into an annular radiator cowling of the same diameter as the 211F but filling in some holes/gaps present between the coolant radiators.

The difference in installation of Jumo 211B and 211J:

 
To move a bit to the more powerful engines - the comparison between DB 603A (the original graph) with added lines for the Jumo 213A (blue) and BMW 801D (fully rated; thick red; thin red is for overboost above 1.42 ata). Above 6 km, the DB 603A (on B4 fuel) will make 10% more power than the 801D (C3 fuel), with perhaps main bonus being that overall drag will be decreased.

 
Sorry, I don't think I was very clear with my phrasing before. I'd meant to say that the 211J's arrangement is generally more useful all around than a hypothetical 211F with similar power levels achieved through water/rich mixture injection. (an overboosted 211F running C-2 or C-3 might be more useful, but it won't help altitude performance any)


The separate point was that using higher supercharger ratios with the 211F's intercooler should still be practical at the expense of increased charge heating as with any supercharger arrangement. (but still be better off than similar supercharging without intercooling)




You don't think there's any way of managing an embedded or retractable radiator with significant improvements over the annular arrangement? (especially for the 211F without concerns for the intercooler)

This same issue came up before on the high speed Ju 88 design discussion (with embedded wing radiators suggested over the annular ones) though I suppose the Ju 88 offers a lot more space for that sort of compromise.

It all depends on how long it would it take for the DB to sort out the 603A, and how good supercharger set-up is installed on the DB 601(E), plus whether it would be easy to rev-up the 601E to 2800 rpm, like the 605 managed eventually.
I was suggesting the 603 emphasis more in leu of the bearing shortages that forced some of the redesigns in transition from DB 601 to 605. (with continued use of ball bearings, the 601 -or alternate 605- might have had an easier time with higher RPM as well)

As above - methinks that the DB 601E 605A would need less fiddling with, in order to achieve a bit better performance. Probably, the engine that 1st is to get a workable 2-stage S/C is the 'winner'.
Larger single stage supercharged arrangements seemed to work well enough too (an intercooled DB-605AS should have covered most of the needs without resorting to a 2-stage arrangement or requiring water injection). The swirl/radial throttle guide vanes on the 213 also helped smooth power curves even better than the DB's fluid coupling in some respects. Having the latter available on the 211 earlier would have probably been more important than a 2-stage arrangement and probably more important than intercooling. (the upgrade from the crappy supercharger in the 211A-D series to the ones of the F was important for sure)



Interesting that the 213A manages best power at the low altitude ends of its 2 supercharger speeds. I'as assume the critical altitudes would remain rather similar in height and power output for a simpler throttle plate configuration which implies the radial guide vanes actually improve power under dense air + restricted flow conditions and that a similar configuration applied to the earlier 211 models should have significantly increased their power at all heights outside of critical altitudes (or above 2nd speed crit alt) as well as making peak power output at SL. (possibly allowing the 211J to outperform the 605A, or the 211F to directly compete? -possibly without the added reliability problems suffered by the 211N depending what the cause of that actually was)
 
For radiators the retracting scheme may be a dead end.

A major source of the drag is the airflow through the radiator core or matrix. It depends on what the pressure drop is of the air moving through the radiator. A small area radiator with a high pressure drop is just as bad as a large radiator with a low pressure drop. This was part of what made the Mustang good. The air entered through the bottom scoop and the duct rapidly got larger which slowed the air before it hit the radiator core/matrix. the slower speed helped a lot because drag goes up with the square of the speed. The Mustang was trading volume inside the airframe for a low drag installation. Using short front to back radiator cores shoved out into the airstream (even part way) is like partially deploying an airbrake.
 
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You don't think there's any way of managing an embedded or retractable radiator with significant improvements over the annular arrangement? (especially for the 211F without concerns for the intercooler)

I agree with SR6 here - the retractable radiator would bring more bad than good re. streamlining.


The advantage of the 2-speed S/C with the swirl throttle vs. hydraulically driven S/C with 'normal' throttle is that losses due to slippage at lower altitudes are non-existant, so there is more power left to drive the prop. Advantage of DB s/c drive is that is available 5 years earlier historically for the LW, and it too can have the swirl throttle installed, like it was the case with DB 605L and 603L (the 2-stage supercharged engines).
The swirl throttle cannot increase the rated altitude, however, and this is why I've suggested the 2-stage S/C for the DB 601/605 and Jumo 211 (hopefully inter-cooled, and that will increase power vs. non-intercooled engine variant) - LW have had plenty of fine engines for under 20000 ft work, the Allied multi-stage engines reigned supreme above that altitude, when we talk about service engines from late 1943 to May 1945.
At 10 km and vs. DB 605A, the DB 605AS offered ~170 HP more (about equaling the Merlin 66), the DB 605L was offering 550+ PS more (like 2-stage RR Griffon). That is quite a difference.



Swirl throttles are the key to the increase in power under the rated height. Indeed the rated height will remain the same with simple throttle, but obviously the 213A (and othe 213s) will loose a good deal of power under the rated heights in that case.
As above - the improved throttle device will not increase the rated height, but more power down low will come in handy, especially for bombers and fighter-bombers.

(possibly allowing the 211J to outperform the 605A, or the 211F to directly compete? -possibly without the added reliability problems suffered by the 211N depending what the cause of that actually was)

I wouldn't be so sure that 211J (let alone the 211F, that was of lower power than the DB 601E already) will be outperforming even a restricted DB 605A. The 605A can still make 2600 rpm for 30 minutes, the 211J for 1 minute historically (take off only), and maybe 5 min in a faster flying fighter. The 605A has smaller drag due to the lack of intercooler, and it is even 4 cm narrower (not that it will mean anything for the installation on the Fw 190).
 
A retractable radiator would still have advantages in drag over a similar fixed radiator, wouldn't it? The He 100's example for takeoff/ground running is a bad example as it's not ducted/cowled. I'm thinking more in line with designs intended to be used in-flight like the single seater Fw 187 prototypes, He 111, and I believe some He 112 prototypes.

I'd think the major trade-offs would be added weight and complexity for the retraction system, and internal space consumed. (though the latter shouldn't be any worse than a similarly sized burried radiator)
Hmm ... perhaps I've answered my own question though ... a fixed, burried radiator with similar location and just a retractable intake scoop might work better and be lighter. (admittedly, the Fw 187 prototypes actually appear to use that configruation more so than actually retracting the radiator core)

Still, there must be some reason the He 111 didn't adopt the Junkers style annular radiators.


Thinking on this again, I had originally meant to imply more of a 'beard' type radiator under the nose (like P-40, Typhoon/Tempest, Ju 87, Bf 109A/B/C/D, etc) but that might not work as efficiently on an inverted V arrangement than an upright V. (or have few/no advantages over the annular placement) The P-40Q seems to have slimmed it down a good bit (and the P-40B/C was more streamlined as well, or at least appeared so aesthetically) but I'm not sure that would mean so much for the Jumo or DB engines. In all cases you'd still want some sort of ducting/cowling arrangement with boundary layer splitter and radiator cores shaped/placed accordingly. (having ram ducting and diffusion area like the P-51 used is another matter entirely and requires a lot more space)



At 10 km and vs. DB 605A, the DB 605AS offered ~170 HP more (about equaling the Merlin 66), the DB 605L was offering 550+ PS more (like 2-stage RR Griffon). That is quite a difference.
Agreed there, but I think the point of potential for an intercooled 605AS still stands. Similarly there should have been more room for single stage (with and without intercooling) growth on the 211 itself. The 213A seems to have maxed that potential out though, or come close enough. (same for the 605AS and the 603A)

I was more suggesting that the 211 might make better competitors had the swirl throttle been available sooner (and assuming Jumo got it working satisfactorily earlier than DB). The added power below critical altitude might make the 211F and J better for low level operation than the 601E and 605A (or at least more attractive with weight and production volumes in mind). 211N would be more interesting but as you mentioned also seems to have reliability issues, at least in testing on the Ta 154.
 
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In the case of XP-40Q, two radiators were relocated in the wings, hence the smaller 'beard' that now housed only one (oil?) radiator.


The annular radiator circumvents the need to have the boundary layer splitter. In case we want a P-51-style radiator, one of the fuel tanks must go - not such a big problem, there is enough of space between the spars for fuel tanks, but still a work to be done.


The Jumo 213A and DB 603A/E were among the best 1-stage engines, once sorted out. Strong points being the ability to use 87 oct fuel and still perform, the shortcoming being greater weight and bulk, as well as lower power above 20000 ft than a decent 2-stage supercharged 700-750 kg (dry) engine, let alone with 2-stage 1000 kg engines.
 

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