Best radial fighter of '42

Hi Vincenzo,

>HoHun can you recheck P-36A graphs? (maybe best take out R-1830 variant graphs for R-1820 variant)

Hm, I think the Mohawk IV would be the best choice, but I don't have good data on the R-1820-G205A it used.

Here is some basic data, but it doesn't give full throttle heights or power at full throttle heights:

Reference

What is the propeller diameter of the Mohawk IV? 9' 9" like for some earlier variants?

Regards,

Henning (HoHun)

Hi Vincenzo,

>i've collected some info on time to climb (i've not collected data for the top rated: Fw 190, La 5, Type 2 and Type 0)

Without weight and power setting data, such climb figures don't tell us much, I'm afraid.

They are not so important for my analysis anyway as it does a rather good job of calculating it from other data.

Regards,

Henning (HoHun)

Hi Elvis,

>Since we're talking about radial-engined fighters, the best way I can think of to down an early 190 is to play with him until his engine won't run anymore.

Hm, the initial overheating problems were long cured by the time the Fw 190A-4 relevant for our comparison came out. Besides, the performance advantage of the Fw 190A is so serious that it would probably be able to beat most other fighters at a reduced power setting too

>...that's why the German's switched the 190's power to a liquid cooled V-12.

No, it's not. The DB 603 and Jumo 213 simply were all-around more powerful engines with less frontal area as a bonus, that's all.

Regards,

Henning (HoHun)

Hi Ivan,

>I once wondered why there was no improvement in BMW 801 engine performance after about 1943. Turns out that there WAS a serious improvement though it is a bit more difficult to quantify than most. "C3 Einspritzung" was a means for this engine to essentially run WEP for as long as it had fuel. Output was in the 2000-2100 HP range WITHOUT MW-50.

From what I've read in Dietmar Hermann's articles, it appears that there was a "hidden" performance improvement over time that was not documented in manuals. Initially, the BMW 801D-2 was only cleared for emergency power for 3 minutes (when it was finally cleared for that power setting at all), but when the trials for C3 injection were ran, the engines were able to be run at emergency power for a much longer time even without the additional injection.

Difficult to track, of course, but I think this was evolutionary improvement of the basic engine without change of designation. The BMW 801E/F engines that were supposed to be leaps forward in performance ran into difficulties and never really went into series production, though the engine of the Fw 190A-9 was a "bastard" with some features of the new models applied to the old BMW 801D-2.

Regards,

Henning (HoHun)

Maybe usefull a new list of challengers with explanation
Transition fighter
D. XXI (Twin Wasp Jr SB4-C or G variant in a squadron (it's called fighter squadron but principally used in naval attack) of Finnish Air Force, there are also a few with Mercury VII in a recce squadron) 2,5
Type 96 Navy Fighter (model 24 and 34) (engine kotobuki 41 o 41 kai) (japanese navy principally ground unit) 1
Type 97 Army Fighter (engine Ha-1b (army name for kotobuki) (japanese army, thay and manchurian air forces) 1

Low/intermediate
F2A-3 (engine R-1820-40) (USMC) 8,5
Model 339C (engine R-1820-G105) (nederland east indies) 6
Model 339D (engine R-1820-G205) (nederland east indies) 6
Model 339E (engine R-1820-G105) (RAF and CW air forces) 6
Model 239 (engine R-1820-G5) (Finnish air force) 7,5
P-35A (engine R-1830-45) (USAAC) 5,5
Mohawk IV (engine R-1820-G205) (RAF) 4
Hawk 75A-7 (engine R-1820-G205) (nederland east indies) 2,5
Hawk 75A (engine R-1830-SCG and 1G, 2G, 3G) (finnish air force) 2,5 or 3,5
H-75 C1 (engine R-1830 as finnish) french name for A-1/A-3 2,5 or 3,5
CW-21B (engine R-1820-G5) (nederland east indies) 5
Lancer (engine R-1830-57) (chinese air force) 9,5
I-16 Type 18 and 27 (engine M-62 it's a derivative of Cyclone) (soviet air forces, maybe some allied air forces) 4,5 (18 ) o 13,5 (27)
I-16 Type 24, 28 and 29 (engine M-63, as above) (soviet air forces maybe some allied air forces) (the use of old variant with M-25 engine it's possible, but i think it's very hard that were in fighter unit. also for this more recent variant the use on attack unit was common) 4,5 (24) 13,5 (28 ) 6,5 (29)
F4F-3 (engine R-1830-76) (USN) 9,5
F4F-3A (engine R-1830-90) (USN) 9,5
F4F-4 (engine R-1830-86) (USN) 14,5
Martlet I (engine R-1820-G205) (FAA) 9,5
Martlet II (engine R-1830 SC4G) (FAA) 14,5
Martlet III (engine R-1830-90) (FAA) similar to F-3A 9,5
G.50 (engine A-74 RC38 it's a derivative of R-1830) (italian air force, finnish air force) 2,5
M.C.200 (engine A-74 RC38 it's a derivative of R-1830) (italian air force) 2,5
Re. 2000 (engine P.XI RC 40 it's a derivative of G.R. 14K) (hungarian air force, italian air force, principally variant with more fuel and less performance) 2,5
Type 1 Mark I Army Fighter (engine Ha-25 (army name for sakae)) 1,5
IAR 80 (engine IAR 14K, it's a copy of G.R. 14K, from 80A 14K 1000, firsts 20 IAR 80 14K III, and the others 30 14K IV) (romanian air forces) 3,5 (80)
5,5 (80A) 12 (80B)

Top
Type 0 Navy Fighter (engine: model 21 sakae 12, model 32 sakae 21) (japanese navy) 10
Type 2 Mark I Army Fighter (engine Ha-41) (japanese army) 4,5
La 5 (engine M-82, a development of M-62) (soviet air forces) 11
Fw 190 (engine BMW 801 D-2 for A-3/4, C-2 on A-2 (early variant no more in operations)) (luftwaffe) 31,5

HoHun
sorry have not info on propeller of Mohawk IV

for G-205 see here
Wright Cyclone 1820 radial engine
but table in your link trial that G-205 was not the engine of US buffalo (the 205 was best)

Great work, Vincenzo.

Hi Vincenzo,

>but table in your link trial that G-205 was not the engine of US buffalo (the 205 was best)

I'm still trying to find some data on the Mohawk IV, but the R-1820-G205A seems to have been very similar to the R-1820-56, and the commonly reported 520 km/h @ 4600 m top speed for the Mohawk IV just doesn't match the engine's critical altitude.

I would also think that if the P-36A data is realistic, an engine with a two-speed supercharger would yield a much higher speed due to power remaining high at altitude while air resistance drops, so I'd have expected the Mohawk IV to be markedly faster in absolute speed than the P-36A.

No idea how to fix this ... more data would be required. Didn't the Finns operate Hawks with the R-1820-G205 engine? It would be interesting to know whether they made any speed measurements (and at which power settings, of course).

Regards,

Henning (HoHun)

from my link "1000 hp at 2500 rpm at 14,200 ft." , 4600 are 15100 ft i think it's right.
Yes finns operated with hawk with cyclone but in late '41 they replaced the engines. (finns data for hawk 75 with cyclone: 462 km/h at SL, 520 km/h at 4600, climb a 3 km in 3'12'' a 6 km in 7'36'')

p.s. back to P-36 in the graphs i think that the best speed altitude it's too low, under 1 km.

Hi Vincenzo,

>from my link "1000 hp at 2500 rpm at 14,200 ft." , 4600 are 15100 ft i think it's right.

Hm, according to enginehistory.org, the R-1820-G205A is almost the same as the R-1820-56, and I have a good engine chart for the latter so that I was able to confirm that the full throttle height is close.

However, there is one aspect not covered by the enginehistory.org summary, and that' the supercharger diameter. If the R-1820-56 had a larger supercharger diameter, my assumption might be off, but I don't have any data on that. Did the R-1820 line change supercharger size at some time?

>Yes finns operated with hawk with cyclone but in late '41 they replaced the engines. (finns data for hawk 75 with cyclone: 462 km/h at SL, 520 km/h at 4600, climb a 3 km in 3'12'' a 6 km in 7'36'')

Cyclone is R-1820, isn't it? My data matches the times to altitude very closely (3:08 instead of 3:12, 7:25 instead of 7:36). However, if I drop the full throttle heights to match the horizontal speed, I end up with 9:03 min to 6000 m. Of course, it depends a lot on aircraft weight, and I'm using an aircraft weight of 2608 kg - what did the Finns use?

>p.s. back to P-36 in the graphs i think that the best speed altitude it's too low, under 1 km.

That's correct, it's the standard R-1830-17 using 100 octance, running at emergency power with 2700 rpm. It gave high power but only at very low altitude. Curtiss data for the P-36A is just above 500 km/h @ 3 km, so a P-36 with an engine capable of achieving the same power at 4.6 km should be a lot faster in terms of absolute speed.

Regards,

Henning (HoHun)

i don't know
R-1820-G205, not reported weight (almost not in that web page)
-13 was SC-G (if i understand the enginehistory) it's in hawk 75A-1 so they are few raf take 29 A-1/A-2 (this with -19) so and easy that for '42 the engine was replaced or take out from operation.

Hi again,

>i don't know
>R-1820-G205, not reported weight (almost not in that web page)
>-13 was SC-G (if i understand the enginehistory) it's in hawk 75A-1 so they are few raf take 29 A-1/A-2 (this with -19) so and easy that for '42 was engine replaced or take out from operation.

Hm, I have now found on the enginehistory.org page the second document listing the same engine as R-1820-87 with the R-1820-G205A designation in brackets, and now I understand the confusion. (Besides the typo in just that engine's full throttle height!)

The ratings in the more detailed documents are for "Continuous", showing just 2300 rpm. This results in a lower full throttle height.

"Take-off" is achieved at 2500 rpm though where the engine yields 1200 HP instead of its usual rating of 1000 HP. The "military" rating is given as "none" in the document, but if you look at the list of aircraft types the engine was used in, you'll find that they are all training aircraft (or at least were used as such by the USAAF).

Accordingly, the military rating was not allowed for use, and maybe the aircraft were not even fueled with 100/130 grade petrol as listed in the engine overview, but with lower grade fuel to preserve the high octane for combat operations.

The RAF Mohawk IV however would probably have had access to 100 octane fuel, and accordingly used the "military" power rating and performed much better as a result. I'm not sure if the Finnish Air Force had 100 octane fuel available, though.

To get back to the reported 520 km/h @ 4.6 km, this is closer to what I get from the "continuous" rating, though it requries the assumption that the P-36 did not exploit zero ram effect, which contradicts my data on the P-36A. Some engine ratings are given with ram effect, but that would surprise me as the list these ratings are from lists different and fairly slow aircraft types where no coherent assumption on a generic high-speed situation would be possible, so it would be best to list the ratings for static pressure.

Even more importantly, the 2608 kg weight I am using appear to fit the data I have on the P-36 quite well, and with the "continous" power rating I get nowhere near the climb rates you listed while the "military" power rating I derived from the R-1820-56 chart matches them rather well.

My conclusion is that the top speed and the climb rate data is not for the same power setting, and that the Mohawk IV with 100 octane fuel using the military power setting would in fact be much faster than 520 km/h at 4.6 km.

Regards,

Henning (HoHun)

i think that listed speed (520 km/h) for mohawk IV/hawk 75 with G205 it's not for 100 octane fuel.

Hello
the figures Vincenzo gave for FAF H75A are not figures Finns got from their own tests.
CUw-551 max speed at sea level was 429km/h and for CUw-557 max at 1500m was 425km/h. CUw-572 max at SL was appr. 415km/h and max at 3000m appr 438km/h. Max for CUc (c=Cyclone) was appr 480km/h at FTH.
According to British test in Apr 41 max for H75A-4 was 486km/h at 4300m, max climb at 2870kg 13,2m/s and ceiling 10 300m

The propeller was 3 blade Curtiss Electric constant speed, diameter 3,07,m blade angle moved between 29-52 deg

On 100oct, maybe German C3, LeR 1 had a small secret cache of it to be used in Curtiss for to hunt high speed Pe-2 recon planes, but 87 oct was the standard fuel of FAF

Juha

Hi Juha,

>the figures Vincenzo gave for FAF H75A are not figures Finns got from their own tests.

Ah, very important to know!

>Max for CUc (c=Cyclone) was appr 480km/h at FTH.

Was the full throttle height also given?

>According to British test in Apr 41 max for H75A-4 was 486km/h at 4300m, max climb at 2870kg 13,2m/s and ceiling 10 300m

Hm, I can't quite understand the 4300 m full throttle height, and how the aircraft could be so much more draggy than the official Curtiss numbers would indicate, but 13.2 m/s and 10300 m ceiling at this weight appear perfectly in line with the powers given for 2300 rpm.

>The propeller was 3 blade Curtiss Electric constant speed, diameter 3,07,m blade angle moved between 29-52 deg

Thanks! Another vital bit of information

>On 100oct, maybe German C3, LeR 1 had a small secret cache of it to be used in Curtiss for to hunt high speed Pe-2 recon planes, but 87 oct was the standard fuel of FAF

I see. No idea what the 87 octane power limits were on that engine if combat use was considered ... I'll have to see if the FM-2 manual has something to say on that.

Here is a comparison of my calculations for the Curtiss. #1 is for the 520 km/h @ 4.6 km data point, with some leaps to salvage some logic. #2 is for the 486 km/h @ 4.3 km data point, ignoring the higher full throttle height that appears inevitable even with a modest amount of ram effect - thus the top speed exceeding 486 km/h and being reached at almost 5 km.

#2 shows good agreement in the climb data with the British test results you provided if we consider it to be valid for 2300 rpm. At the full 2500 rpm that the R-1820-87 probably used for Military power, performance would be a bit better, as indicated by the thick line.

Regards,

Henning (HoHun)

Good info, for clear
CUw551 was a A-2
CUw557 was a A-6
CUw572 was a A-3
Maybe that the light weight was w/o armour? weight ~2600 kg put with weights for originals french aircraft (gross weights on baugher pages exactly 2608 kg for A-4).

p.s. i must do something i back on forum 17th evenings (my local time)

Hi again,

>No idea what the 87 octane power limits were on that engine if combat use was considered ... I'll have to see if the FM-2 manual has something to say on that.

No luck ... it seems that while British Pilot's Notes usually mentioned limitations for a low-octane substitute, the availability of the correct type of fuel was considered a given by the US

Regards,

Henning (HoHun)

Hi Vincenzo,

>Maybe that the light weight was w/o armour? weight ~2600 kg put with weights for originals french aircraft (gross weights on baugher pages exactly 2608 kg for A-4).

Hm, so it's:

- French Hawk 75A-4: no armour
- British Mohawk IV: armour
- Finnish Hawk 75A-4: armour???

Regards,

Henning (HoHun)

HoHun said:

..how the aircraft could be so much more draggy than the official Curtiss numbers would indicate

Click to expand...

The Finnish State Aircraft Factory wondered the same thing. It suspected that the Curtiss numbers were obtained with a plane that was polished and waxed, antenna, machine guns and all other protruding parts removed.

It was found that at 6000-7000m the Curtiss had to use full throttle to keep up with PR Bristol Blenheim using its cruise speed.