Me 209 - any worth in it?

[Koopernic]

A lot depends on timing. The small cylinder but many cylindered engine has several advantages over a large cylinder engine.
1. The small cylinders offer better cooling. Both due to a higher cylinder wall to volume ratio and and a shorter path for the heat to travel from center of piston to cylinder walls. This allows for higher compression or higher boost than the big cylinder engine can use.
2. The smaller reciprocating parts allow for higher rpm. The DB 604 could turn about 18% more rpm than the DB 603.
3. The smaller cylinders should show higher volumetric efficiency than large ones.

For any given grade/PN number fuel the high rpm small cylinder/multi cylinder (over 12 in the case of inline or V engine) should show a marked advantage over the large cylinder 12.
However there are also a number of disadvantages to the layout/s and the large 12s did NOT stay frozen in time.
Comparing a 1943/44 large 12 to a 1940/41 24 cylinder engine ignores some of the progress made in rings, bearings, piston design and other aspects that helped close the gap. Scaling up only works to a certain extent. Changing the stroke from 160mm to 180mm and keeping the smaller engines rpm means about a 26% increase in loads on the rod bearings and main bearings just from the change in piston speed and doesn't take into account the increased weight of the bigger rods and pistons. Granted the scaled up engine has larger bearings but are they large enough?
In the late 30s many engine designers/companies thought they could just add cylinders or adopt complex engine layouts with little more trouble than they had with the lower number of cylinders. Time proved them wrong. But without the aid of the retrospectroscope it is a lot harder to find fault with them. If all you have is 87 octane fuel you run into limits on how much power you can get from a certain size cylinder pretty quick. The size of the cylinder helps dictate engine rpm. The common V layout was 12 cylinders so the basic limits were pretty well known.
The ways out included better fuel for higher boost/compression. Higher RPM which required better bearings and a much better understanding of harmonic vibration. Or going the 16-14 cylinder route.

I don't really accept all of those arguments as having a significant effect. I think the main issue with big spark ignition cylinders was the propagation velocity of the flame front "deflagration" i.e. sustaining a stable burn that completes in time. One thing that you've listed as an advantage is better cooling is also a disadvantage, you don't want to be loosing heat from an engine, you want to retain it but cool the engine parts.

 

[EKB]

Some engine designers obsessed a bit too much about frontal area.

Official flight test data of the Spitfire and Typhoon would seem to agree with that view.

For example, Typhoon Ib R7700 (8 Nov 1942) and Spitfire IX JL165 (1 Feb 1944). The Napier Sabre and Merlin 66 engines were both supercharged to approximately 2000 bhp for the speed checks. Despite that the Typhoon was a much larger aircraft with its so-called "thick wings", there was hardly any difference from the Spitfire in level speed, at all heights up to 24,000 feet.

The British test pilots were either unable or unwilling to run the Sabre engine at full power during the trials of Typhoon R7700. Napiers advertised 2200 bhp on +9 lbs. Boost, but the A&AEE trials set limits of +7 lbs. Boost for level speed and +6 lbs. Boost for climbs.

 

[Shortround6]

The fuel/air mixture burned a pretty constant rate. Most designers wanted the combustion to be pretty much over with by the time the the piston was about 20 degrees past top dead center. Even with dual ignition this tended to put limits on both the cylinder bore and the stroke. You could use really big cylinders, you just couldn't run them very fast. Most aircraft engines used fixed ignition timing or at most a retard timing setting/device for starting or idle.

Retaining heat in an engine is great for class room theory on efficiency. In the real world of 1930s and 40s the two main problems to getting (and surviving) aircraft engine power were heat and not breaking parts.

Efficiency and max power sometimes need opposite features. The air cooled engines progress in power per liter or power per cylinder of like class engines follows the ability to put sq in of cooling fins on the cylinder. the more sq in of cooling fin surface the more power they could get from the cylinder. The liquid cooled engine didn't follow quite the same chart (and Wright published charts showing power development over the years in relation to cylinder fin area) but youhave the same problem. With any given fuel (87 octane or 100/130) you can only use so much compression and boost and intake temperature. raise the intake temperature 100 degrees and peak temperature in the cylinder goes up 100 degrees and the exhaust temperature goes up the same 100 degrees. Now our engine designer can try to use extra cooling of the cylinder ( and I include the cylinder head here) to lower the temperature a bit so he can use either a bit more boost or compression. the center of the piston was often a weak spot (not just on the DB 605 engine) so distances and "paths" of heat dissipation for the piston were often of concern. Piston either gets rid of heat to the cylinder walls or to oil on the bottom of the piston, either splashed or sprayed.
The Bristol Hercules was another exercise in cooling, it not only went through something like 5 or more cylinder head designs (and a Hercules cylinder head did nothing except seal the top of the cylinder, hold the spark plugs, and provide cooling surface.) and in the post war versions was made of copper alloy instead of aluminium for even more heat transfer. You can worry about heat retention and efficiency of the engine after you stop melting holes in the tops of the pistons or cooking exhaust valves (R-3350s) or suffering other catastrophic failures.

As for volumetric efficiency, there must be something to it. Practically every form of car or motorcycle racing has progressed to more and more cylinders for a given displacement unless the rules prohibit it. And in some cases 2 cylinder engines are given a displacement advantage against 4 cylinder engines to try to even things out.

 

[tomo pauk]

Official flight test data of the Spitfire and Typhoon would seem to agree with that view.

For example, Typhoon Ib R7700 (8 Nov 1942) and Spitfire IX JL165 (1 Feb 1944). The Napier Sabre and Merlin 66 engines were both supercharged to approximately 2000 bhp for the speed checks. Despite that the Typhoon was a much larger aircraft with its so-called "thick wings", there was hardly any difference from the Spitfire in level speed, at all heights up to 24,000 feet.

The British test pilots were either unable or unwilling to run the Sabre engine at full power during the trials of Typhoon R7700. Napiers advertised 2200 bhp on +9 lbs. Boost, but the A&AEE trials set limits of +7 lbs. Boost for level speed and +6 lbs. Boost for climbs.

Maybe this is where the small details kick in. Like the Typhoon having fully-enclosed main undercarriage and a retractable tailwheel, or, one radiator's group vs. two groups? Also, the test of the Typhoon IB R.8762 was said to be using new engine limits of 3700 rpm and +9 psi boost, old limits being same 3700 rpm but on +7 psi - that would be 1900 HP at SL with plenty of ram?
The thicker wing should be having more problems where it would be closer to the critical Mach number - and that's felt more as the aircraft is higher, eg. like the Bearcat with thick wings having no problem at 5000 ft vs. aircraft with nominally more streamlined wings (P-51, Tempest)?

 

[tomo pauk]

I am not sure. All series 5 fighters appear to be much cleaner than the Bf 109 and with more advanced wing profiles. The inferior speed of the tests could be result of derated italian DB 605s plus inferior propellers.

I'm not sure that Italian Series 5 fighters were used any of the advanced wing profiles - the profiles used were pretty much the same as what was used on the MC.200, Re.2000 or G.50. The Bf 109G-6 was good for 620 km/h with gondola cannons and de-rated engine, or same as the G.55 with same firepower and same engine setting. Granted, the G.55 and Re.2005 should be more pleasant to fly since they were with bigger wing.
On the other hand, the ~385 mph of speed is still ~20 mph under the Fw-190A-4 or Spitfire VIII/IX of 1943. We want a 385 mph fighter with Db 605 and serious firepower? Produce the Fw 190 with DB 605.

If you add under wing guns in to 109 to have the same armament as the italian fighters ,the 109 is clearly inferior. Also with their greater fuel capacity the series 5 fighters can operate at higher power levels longer than the 109.
Finally with their overall bigger size could recieve easier additional cooling devices to allow more powerful vertions of the DB605

The only Italian fighter with more fuel was the Regianne, 430 kg (almost 600 L).

 

[dedalos]

I'm not sure that Italian Series 5 fighters were used any of the advanced wing profiles - the profiles used were pretty much the same as what was used on the MC.200, Re.2000 or G.50. The Bf 109G-6 was good for 620 km/h with gondola cannons and de-rated engine, or same as the G.55 with same firepower and same engine setting. Granted, the G.55 and Re.2005 should be more pleasant to fly since they were with bigger wing.
On the other hand, the ~385 mph of speed is still ~20 mph under the Fw-190A-4 or Spitfire VIII/IX of 1943. We want a 385 mph fighter with Db 605 and serious firepower? Produce the Fw 190 with DB 605.



The only Italian fighter with more fuel was the Regianne, 430 kg (almost 600 L).

1) The G55 had inferior propeller and 1300 ps
2) G55 carried much more ammunition than the Bf 109, both for the central and under wing cannons
3)With similar power loading and much superior wing loading , series 5 fighters were not just more pleasant to fly.
4)The spit ix was faster because of the 2 stage supercharger and superior fuel.
FW190A4 was also faster but also using C3 fuel and accepting very High wing loading while the italian fighters B4 fuel,derated db 605s and inferior propellers. Furthermore Fw was faster in a strait Line. In turning would loose Energy faster.
Also,are you sure that the 190 was significant faster than the Re 2005? The G55 appears to be slower but it was big enough to recieve the db603/jumo 213 and with its big wings should have much better handling at altitude than the 109
5)NO WAY Fw 190 could be cpmpetitive with DB 605. NO WAY. It was just too heavy
6) The C 205V was direct development of earlier machi designs, but the G55 and the re 2005 were totaly NEW designs
7) The C205 could also be modifeid to Carry 600 lt of fuel. The G55 carried similar load of fuel with the 109 but being larger had the space for additional fuel

 

[Juha]

Official flight test data of the Spitfire and Typhoon would seem to agree with that view.

For example, Typhoon Ib R7700 (8 Nov 1942) and Spitfire IX JL165 (1 Feb 1944). The Napier Sabre and Merlin 66 engines were both supercharged to approximately 2000 bhp for the speed checks. Despite that the Typhoon was a much larger aircraft with its so-called "thick wings", there was hardly any difference from the Spitfire in level speed, at all heights up to 24,000 feet.

The British test pilots were either unable or unwilling to run the Sabre engine at full power during the trials of Typhoon R7700. Napiers advertised 2200 bhp on +9 lbs. Boost, but the A&AEE trials set limits of +7 lbs. Boost for level speed and +6 lbs. Boost for climbs.

IMHO it is more on the intercooler radiator, see Spit XII (Griffon II 1760 hp at 1,000 ft and 372 mph at 5,500 ft) vs Typhoon Ib (Sabre II 2,180 hp 3,700 rpm and +9lb at sl and 374 mph at 5,500 ft). But radiators and the windscreen were the weak spots of the later part of the war Spits' aerodynamics together with the only partially covered undercarriage wheels.

 

[kool kitty89]

The DB 609 was essentially a V-16 version of the DB 603. It had similar power to the DB 604, but using larger capacity (62l vs 46l) and heavier weight.

V-16s will be longer than an equivalent V-12. The length of the crankshaft and camshafts potentially cause problems. That's why the Chrysler IV-2220 used a central gear drive, essentially making the engine two V8s.

The DB 609, however, had the power take-off at the front.

The frontal area will be lower, but the length will be greater.

A V-16 using the 603's cylinders mitigates all of the advantages and compromises that the suggested DB-601 (or 605) derived V-16 would have. Size, weight, displacement, piston size, piston speed at given RPM, better piston cooling, higher practical RPM, etc. Plus, potentially at least some parts commonality and more directly shared development resources with the DB-601/605.

Though I suppose the same could be argued for Jumo 211/213 derived V-16 development over the Jumo 222. Then again, an X-24 derived from the Jumo 210 may have been more practical than the 222 as well.

Some engine designers obsessed a bit too much about frontal area. A seated pilot, even in the position of having the legs go almost straight out in front has a bigger "frontal" area than many (most) V-12 engines (not including radiator). On a twin engine bomber you have the frontal area of the fuselage being much larger than all but the biggest engines even on a small bomber. Obviously there is a big difference between a 5-6sq ft V-12 and a 16sq ft radial but the difference between a 5-6 sq ft V-16 and a 7-8sq ft V-12 isn't really going to be that great once you add in everything else.

True, though for multi-engine aircraft, the added drag is still notable given it's not hidden by the fuselage, and for either case the difference is more significant as engine sizes go up. (once you have the engine easily being the widest part of the aircraft -without extremely slim/tight fuselages like the Spitfire, 109, and He 100, it's a good deal more significant) The large frontal area is also one of the disadvantages of the Jumo 222. Same for radial engines in general, though the BMW 801 managed to minimize that rather well.

For that matter the BMW 802 might have been more appealing if the stoke had been shortened somewhat to reduce diameter -losing some displacement/power may not have been a bad thing for development/time to service in that case either. (particularly if more compromises had been made on the supercharger and especially for use as a bomber engine)



Edit: I overlooked the X-16 arrangement. That should have been lighter and more compact than the XI-2220's arrangement while maintaining a shorter crankshaft and a single crankshaft rather than coupling at the gearbox. It'd be larger frontal area wise than a V-16 or X-24 of similar displacement, but should be mechanically simpler and easier to develop. (and again potentially share more in common with existing V-12s in development)

Maybe this is where the small details kick in. Like the Typhoon having fully-enclosed main undercarriage and a retractable tailwheel, or, one radiator's group vs. two groups? Also, the test of the Typhoon IB R.8762 was said to be using new engine limits of 3700 rpm and +9 psi boost, old limits being same 3700 rpm but on +7 psi - that would be 1900 HP at SL with plenty of ram?
The thicker wing should be having more problems where it would be closer to the critical Mach number - and that's felt more as the aircraft is higher, eg. like the Bearcat with thick wings having no problem at 5000 ft vs. aircraft with nominally more streamlined wings (P-51, Tempest)?

Weather would be a big factor too, and smaller issues like whether the spitfire had full or clipped wings. Warmer air will further reduce mach related drag issues, while being less favorable in other respects.

It's still hard to believe that a 2000 HP spitfire wouldn't be faster than a 2000 HP Typhoon with that power maintained at given altitudes.
P-51 sure, even with considerably greater weight ... Tempest, maybe, but Typhoon? That'd be about as surprising as the Hurricane managing the same.

 

[Juha]

In fact according a tabular form Spit LF. MK. IX +25 lb boost was 8 mph faster than Typhoon MK.IB (Sabre II +9 lb boost)from S.L. to 4,000 ft (the performance shown was from S.L. to 4,000 ft with 500 ft intervals).
See http://www.spitfireperformance.com/merlin66_18_25.jpg

 

[tomo pauk]

1) The G55 had inferior propeller and 1300 ps

The speed figures I've quoted for the Bf 109 are also for a restricted engine (1300 PS for take off). Any good source to back up the claim that G.55 have had inferior prop?

2) G55 carried much more ammunition than the Bf 109, both for the central and under wing cannons
3)With similar power loading and much superior wing loading , series 5 fighters were not just more pleasant to fly.

You're right about the ammo. The Series 5 should be more maneuverable and easier to take off and land, how do they compare in dive with German and Allied fighters?

4)The spit ix was faster because of the 2 stage supercharger and superior fuel.
FW190A4 was also faster but also using C3 fuel and accepting very High wing loading while the italian fighters B4 fuel,derated db 605s and inferior propellers. Furthermore Fw was faster in a strait Line. In turning would loose Energy faster.

It does not matter why another aircraft of the era was faster, what it matters is that Series 5 don't offer anything above best current Axis and Allied fighters, while they lack in speed. The Fw 190 will loose the energy in turn faster, but it will be rolling faster (thus entering the turn faster).
Granted, from late 1943, the ratings for the DB 605A will be upped, so we'd see Series 5 doing ~650 km/h (the lightly armed MC.205V even faster), thus equaling the Spit IX and Fw 190A-6. The P-47 and Merlin Mustang will up the bar, however.
We can recall that LW was fielding a fighter with 4 cannons and 650 km/h as early as winter of 1941/42.

Also,are you sure that the 190 was significant faster than the Re 2005? The G55 appears to be slower but it was big enough to recieve the db603/jumo 213 and with its big wings should have much better handling at altitude than the 109

660-650 km/h for the Fw 190A3 to A6, 630 km/h for the Re.2005 in best part of 1943. The G.55 was at 620 km/h, it have had the biggest wing of the '5' fighters - thus the refit with DB 603A (=G.56) should've made it an excellent fighter with 3 cannons and 685 km/h claimed.

5)NO WAY Fw 190 could be cpmpetitive with DB 605. NO WAY. It was just too heavy

Exchange from BMW 801 to DB 605 means plenty of weight and drag is lost. The BMW 801D was above 1000 kg without oil system, pumps generators, mounts and cowling; whole powerplant was heavier than 1600 kg.

6) The C 205V was direct development of earlier machi designs, but the G55 and the re 2005 were totaly NEW designs
7) The C205 could also be modifeid to Carry 600 lt of fuel. The G55 carried similar load of fuel with the 109 but being larger had the space for additional fuel

I've checked out a bit, and yes, the G.55 also carried plenty of fuel (part of it behind the pilot). Not the MC.205, though. The wing profile of either of Italian fighters is not offering anything new, however.

 

[dedalos]

The speed figures I've quoted for the Bf 109 are also for a restricted engine (1300 PS for take off). Any good source to back up the claim that G.55 have had inferior prop?


You're right about the ammo. The Series 5 should be more maneuverable and easier to take off and land, how do they compare in dive with German and Allied fighters?



It does not matter why another aircraft of the era was faster, what it matters is that Series 5 don't offer anything above best current Axis and Allied fighters, while they lack in speed. The Fw 190 will loose the energy in turn faster, but it will be rolling faster (thus entering the turn faster).
Granted, from late 1943, the ratings for the DB 605A will be upped, so we'd see Series 5 doing ~650 km/h (the lightly armed MC.205V even faster), thus equaling the Spit IX and Fw 190A-6. The P-47 and Merlin Mustang will up the bar, however.
We can recall that LW was fielding a fighter with 4 cannons and 650 km/h as early as winter of 1941/42.



660-650 km/h for the Fw 190A3 to A6, 630 km/h for the Re.2005 in best part of 1943. The G.55 was at 620 km/h, it have had the biggest wing of the '5' fighters - thus the refit with DB 603A (=G.56) should've made it an excellent fighter with 3 cannons and 685 km/h claimed.




Exchange from BMW 801 to DB 605 means plenty of weight and drag is lost. The BMW 801D was above 1000 kg without oil system, pumps generators, mounts and cowling; whole powerplant was heavier than 1600 kg.



I've checked out a bit, and yes, the G.55 also carried plenty of fuel (part of it behind the pilot). Not the MC.205, though. The wing profile of either of Italian fighters is not offering anything new, however.

It DOES matter why the FW was 20 km/h faster against the 1300 ps series 5 fighters. In order to gain speed used a smaller wing which resulted in very High wing loading which is BAD for rate of climb and manouverability. Also required the precious for germany C3 fuel. By the way the 801was more fuel hungry than the 605.
A G55 with 1475 Ps and the AS engine would be practically as fast as the 190A8 below 6000m and faster above that altitude, not to mention far superior handling. If we add c3 fuel or MW50 would be faster at all altitudes. Also would have a marginal power to weight advantage
You are right that Lw had from 1941/42 an 650KM/h fighter with 4 cannons. Yes, but that fighter was a dog above 6500m from the beginning. And with little space for improvements without major redesign. In order to reach 685 km/h it required an inline engine much heavier and powerful than the db 605, and despite sacrifising 2 cannons it still had an wing loading of over 230kgr/m2. I estimate that the G55 could reach that kind of speed on DB605D with a wing loading in the area of 185kgr/m2. Plus it carried 35 lt more fuel and a more economical engine. And bigger wings for additional tanks.

 

[kool kitty89]

Exchange from BMW 801 to DB 605 means plenty of weight and drag is lost. The BMW 801D was above 1000 kg without oil system, pumps generators, mounts and cowling; whole powerplant was heavier than 1600 kg.

I was also suggesting said developments start back with the 601 in parallel with the original 190 prototypes (possibly as a superior alternative to the He 100 -and more versatile total replacement for the 109), so more potential divergence in structural strength/weight requirements for a totally lighter aircraft. (possibly also being better suited to the original small wing, though the larger area/lower wing loading and easier handling of the full sized wing might be preferable)

The 190 airframe would probably be easier to adapt to the Jumo 211 if the need/demand arose as well. (certainly easier than the He 100, possibly easier than the 109) And that option becomes more interesting once the 211F appears. (stronger crankshaft, higher rpm, pressurized cooling, more efficient supercharger, and potential further power boost for low-altitude optimized engines for ground attack and low-alt fighter work more needed on the eastern front) Perhaps more akin to an overboosted merlin powered P-40 in power/weight and overall size. (or maybe more like a P-40E/K using overboost/WEP down low but also with a high gear setting closer matching the 9.6:1 supercharger -so ~1,570 hp at ~4000 ft and 1,480 hp at ~10,000 ft with RAM)

 

[Denniss]

Didn't the italian DB-engined fighters use german props or at least licence-built german props, the same as used by Bf 109 with DB 601A/605A ?

 

[SpicyJuan11]

So what would it take to get the Me 209 to be a great successor to the 109 and still keep the same amount of hoped part commonality? Or would it have been better to go with the G.55/56? If so, why didn't they?

 

[tomo pauk]

It DOES matter why the FW was 20 km/h faster against the 1300 ps series 5 fighters. In order to gain speed used a smaller wing which resulted in very High wing loading which is BAD for rate of climb and manouverability. Also required the precious for germany C3 fuel. By the way the 801was more fuel hungry than the 605.

"There ain't such thing as a free lunch" applies as ever, along with 'every device is a compromise'. The strong points of the wing were excellent roll rate, plenty of internal space and (reasonably) low drag for good turn of speed. Stick a bigger wing and there is a gain in maneuverability and turn rate; shortcomings are decrease of roll rate (that is also a part of overall maneuverability), decrease of G limit and a small loss of speed. We can note that early Fw 190 was able to handily outclimb the lighter Spitfire V, as well as the USN Corsair and Hellcat, while the high roll rate was rated high in Allied reports about the Fw 190, whether from combat or from testing.
If we're worried about the prodigious rate of C3 consumption - stick the DB 605A on the Fw 190.

A G55 with 1475 Ps and the AS engine would be practically as fast as the 190A8 below 6000m and faster above that altitude, not to mention far superior handling. If we add c3 fuel or MW50 would be faster at all altitudes. Also would have a marginal power to weight advantage

It would be certainly a far better performer than the 190A-8.
But there are flaws in your comparison - the Fw 190 was giving in winter of 1941/42 what the 'G.55AS' would be giving in Spring of 1944; everybody important was a better performer than the 190A-8, too.

You are right that Lw had from 1941/42 an 650KM/h fighter with 4 cannons. Yes, but that fighter was a dog above 6500m from the beginning. And with little space for improvements without major redesign. In order to reach 685 km/h it required an inline engine much heavier and powerful than the db 605, and despite sacrifising 2 cannons it still had an wing loading of over 230kgr/m2. I estimate that the G55 could reach that kind of speed on DB605D with a wing loading in the area of 185kgr/m2. Plus it carried 35 lt more fuel and a more economical engine. And bigger wings for additional tanks.

The bolded part would be expected from some LW-basher, and it is wide from the mark. Fw 190 possessed THE fighter airframe of ww2 (for land-based fighters), and was seldom equaled, let alone surpassed by another piston-engined airframes.
Neither RAF, nor USAF, nor VVS were of opinion that Fw 190 was a dog above 6500 m, at least not prior mid 1943.
Why would you give the DB 605D for the G.55, and not to the Fw 190?? The engine of late 1944 (DB 605D) is not available in late 1943 (Jumo 213A, DB 603A); that LW failed to have Fw 190C/D in winter of 1943/44 is the fault of the RLM/LW themselves, not the incapability of Jumo or Fw. The G.56 was stated as 685 km/h fast, BTW.
Again - we're worried about high wing loading? Stick the DB 605A/AS/D on the Fw 190.
As for the fuel - there is enough of space between the wing spars of the Fw 190, the late Doras were to have 4 fuel tanks installed there as Rustsatze. Plus, the drop tank facility - we have it on the Fw 190 (up to 3 tanks), the G.55 will need a modification in order to have them.

 

[The Basket]

The Italian fighters didn't have anything better than the 109, maybe they were better aircraft but to cancel the 109 for a marginal replacement is hardly clever.
He 100d. Now that is another ballgame.
I see no problem with advancing Me 209 and trying to build a better fighter. If it doesn't work then that's called engineering.

 

[Shortround6]

He 100d. Now that is another ballgame..

Yep, a total loser. There was nothing wrong with the He 100 that throwing the whole thing out and starting over wouldn't have fixed.
It offered very good speed on the engine power available but after that things go to pot in a hurry. None of them were ever fitted with armor or self sealing fuel tanks, it had a very large, cumbersome and vulnerable cooling system, it had limited space for armament as built. Now, most if not all things could be fixed but then you wind up with a plane so far from the original there is no point in trying to estimate performance based on the He 100 numbers.

 

[GrauGeist]

Yep, a total loser. There was nothing wrong with the He 100 that throwing the whole thing out and starting over wouldn't have fixed.
It offered very good speed on the engine power available but after that things go to pot in a hurry. None of them were ever fitted with armor or self sealing fuel tanks, it had a very large, cumbersome and vulnerable cooling system, it had limited space for armament as built. Now, most if not all things could be fixed but then you wind up with a plane so far from the original there is no point in trying to estimate performance based on the He 100 numbers.

The final emulation of the He100 was far from being a loser. It had the nessecary armor and conventional cooling system and was armed with two MG17 or two MG151/20 in the wings and the provision for a MG FF motorkannone.

While the combat dress did give it a performance penalty, it was still capable of max. speeds over 400 mph and a combat range twice that of the Bf109E.

What most likely killed the He100, was the fact that it relied on the DB601, which was in great demand for the Bf109 and Bf110 at the time because Daimler's difficulty in producing the 601 in sufficient numbers.

 

[Shortround6]

Any source for the MG 151/20mm guns actually going in the wing roots?

A pair of MG 17 machine guns is hardly first class armament. the MG FF may or may not have been fitted in actuality. I don't believe the ones the Russians got had it. ANd even if fitted there are no reports on how well it worked and the 109Es couldn't get the gun through the prop to work reliably. The Fs did but that is a bit after the He 100. There was talk and drawings/sketches of a wing with two MG 17s in each wing root but I am not sure if it was ever built or flown. It probably could have been built but we keep getting further from the condition/configuration the performance numbers are for.


Some of them may have been fitted with armor, Is there any evidence they were fitted with self sealing tanks?

The cooling system was never conventional. A retractable radiator was fitted but more a supplement to the cooling surfaces in the wings than a total replacement. The oil cooing system was never changed from the oil cooler being suspended in an alcohol tank behind the pilots seat with cooling surfaces for the alcohol being in the turtle deck, the horizontal stabilizers and the vertical fin. Quite a number of sq ft for bullets to hit and compromise the oil cooling system. Granted it is not an instant kill but what happens when a certain amount of alcohol leaks out?

 

[EKB]

Weather would be a big factor too, and smaller issues like whether the spitfire had full or clipped wings. Warmer air will further reduce mach related drag issues, while being less favorable in other respects.

It's still hard to believe that a 2000 HP spitfire wouldn't be faster than a 2000 HP Typhoon with that power maintained at given altitudes. P-51 sure, even with considerably greater weight ... Tempest, maybe, but Typhoon? That'd be about as surprising as the Hurricane managing the same.

Squadron Leader Neil of No. 41 Sqn noted that Spitfires built to Mk XII specs (1735 bhp with +12 lbs. Boost) were good for only 325 mph at sea level; or about 20 mph slower than the prototype.

" In the air, the Mk XII behaved much like any other Spitfire except that the engine was a good deal rougher than the Merlin — it grumbled rather than buzzed — and the beat of the big four-bladed airscrew was very pronounced. It was about 30mph faster low down than the Mk V for roughly the same engine settings, the nose wagging about like a terrier's tail with any change of power. There being no provision for emergency boost — there was rather too much 'urge', anyway — 9lb was obtained with the throttle at the gate and 12lb beyond it, at which setting a genuine 325mph could be achieved at sea level.
As with earlier Spitfires, the aircraft's maximum performance was obtained at around 18,000ft, where the second stage of the supercharger was engaged manually, using a lever on the left-hand side of the cockpit. In common with all two-speed superchargers, it came with a slightly worrying 'clump' although we seldom found ourselves using it as, more often than not, we were at 1,800ft rather than 18,000."

According to Jeffrey Quill, the Merlin 61 equipped Spitfire Mk IX did about 310 mph at sea level, which was rather disappointing performance in view of the high output engine (1570 bhp on +15 lbs. Boost). His favorite Spitfire was DP845 (the prototype Mk XII) which clocked in at 346 mph at sea level per the A&AEE.