Technical handicap of Finnish Air Force?

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durb
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Re: Technical handicap of Finnish Air Force?

Post by durb » 03 Sep 2014 13:31

Performance comparison between Fokker D XXI (Mercury), PZL P 24 and Hawk 75 fighters using all (?) 87 octane fuel:

Fokker D XXI
max. speed:
348 kph at sea level
418 kph at 5000 meters
crusing speed:
330 kph
rate of climb:
6½ minutes to 5000 m
flight time max:
2½ hours
service ceiling: 9600meters
armament:
4 x 7,7 mm mg

PZL P 24 (Gnome-Rhone Kfs 14)
max speed:
410 kph at 4000 m
rate of climb:
7½ minutes to 5000 m
service ceiling:
9000 meters
armament:
4 x 7,9 mm mg or 2 x 7,9 mm + 2 x 20 mm c

Hawk 75 A:
max speed:
400 kph at sea level
450 kph at 4600 meters
rate of climb:
9½ minutes to 5000 m
service ceiling:
8150 meters
armament: 4 x 7,7 mm

Enemy planes to be compared (the main Soviet fighter I-16 + SB 2 and DB 3 bombers):

Polikarpov I-16 type 5 / 10 (M-25/M-25B)
retractable landing gears/skis
max. speed:
440 / 450 kph at 5000 meters
rate of climb:
6 min to 5000 meters
service ceiling:
9100 m

SB 2 M-100 (M-103)
max speed:
395 kph at 5000 m (372 kph at 3250 m)
rate of climb
12 minutes to 5000 m (11 minutes to 5000 m)
service ceiling:
9000 m

DB-3
max speed:
405 kph at 400 m
rate of climb:
12 minutes to 5000 meters
service ceiling:^
9600 m

Above is based on Haapanen 2002 (Suomen Ilmavoimien hävittäjähankinaat 1918 - 1945) and Suomen Ilmavoimien historia, vols. 5, 7 and 9. I used also various web sources like the much maligned wiki (on PZL P 24 I checked Polish wiki) - for the SB 2 M-100 I looked on this: http://www.ctrl-c.liu.se/misc/ram/sb-2m-100.html
We can see that Fokker D XXI and PZL P 24 had just enough speed to catch bombers.
The comparison was interesting. I was surprised how slow climber Hawk 75 was. Less advanced Fokker D XXI was much better when it came to fast climbing, which is very useful for interceptor. The Hawk 75 would have been better against Soviet fighters as a frontline plane.

One option available for FAF would have been North American NA 16-15 (or NA-50, in USA P-64) which participated in the purchase competition of FAF in 1936. It was reasonably fast (430 - 440 kph at 3000-4000 meters) and it would not have been expensive (actually it was cheaper than Fokker). NA 16-15 was dismissed because there were no option to place cannons in it - looking it afterwards that was nonsense because they did not use the option to place cannons in Fokkers either. Here a wiki entry to NA 16-15: http://en.wikipedia.org/wiki/North_American_P-64

There are still strange things with Fokker adquisition to be investigated. There were no test flights of Finnish pilots with Fokker D 21 before the decision to buy it was made. They did not test the cannon option (which was one of the reasons to buy Fokker instead of NA 16-15) - and ultimately Fokkers were armed only with machine guns like NA 16-15. Fokker was not the best option in terms of price/quality. In today´s world this kind of deal would not be possible, it would be investigated thouroughly. It would certainly have rised a question about the possible bribes paid by Fokker company. But probably it was just laziness to check seriously alternatives. USA was so far away and well-known Fokker so near...

Mangrove
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Re: Technical handicap of Finnish Air Force?

Post by Mangrove » 03 Sep 2014 18:40

durb wrote: When it comes to bombers, Blenheim Mk I and IV were modern and good during Winter War, but by 1942/1943 already outdated with their slow speed and limited bombload - however Finnish aircraft industry manufactured Blenheims up to 1944.
Blenheim Mk. IV (Finnish) was equally fast as IL-4, but 30-50 km/h slower than PE-2 and A-20. However, Blenheim required a lot less runway to clear 20 meter tall obstacles (e.g. trees) and still carried around 900-972 kg of bombs.

The length of the (soft) runway in some Finnish aerodromes in 1942-1943:
Onttola (Joensuu): 1100 m
Immola: 950 m
Kymi: c. 800 m
Malmi: 800 m (concrete)

The length of the runway needed for the plane to take-off with near maximum bomb load:
PE-2: 1290 m
Ju 88: 1280 m
IL-4: c. 1000 m
Blenheim Mk. IV (Finnish): 700 m

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Re: Technical handicap of Finnish Air Force?

Post by Juha » 27 Sep 2014 18:01

durb wrote:...Light bomber and recce planes: the Fokker C X was outdated already by 1939 and can not be considered as a good bargain for Finnish Air Force. ..
Now fairly early in the war it was find out that the army co-op planes were an obsolete category. But in 1939 at least most AFs had them and Finnish pilots liked C X more than Westland Lysander, which was the most modern RAF's army co-op type in service in 1939. And C X could carry more bombs than LW's Hs 126 or JAAF's Ki-36 and was probably better dive-bomber than neither of those. So most of the modern AFs had Army co-op planes in 1939 and C X was one of the most suitable planes of that category for FiAF, so IMHO without hindsight it is rather difficult to blame FiAF on purchasing the type. But of course FiAF would have needed more fighters.

Mangrove
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Re: Technical handicap of Finnish Air Force?

Post by Mangrove » 30 Sep 2014 13:06

Juha wrote:
durb wrote:...Light bomber and recce planes: the Fokker C X was outdated already by 1939 and can not be considered as a good bargain for Finnish Air Force. ..
So most of the modern AFs had Army co-op planes in 1939 and C X was one of the most suitable planes of that category for FiAF, so IMHO without hindsight it is rather difficult to blame FiAF on purchasing the type. But of course FiAF would have needed more fighters.
According to a Finnish Air Force memo dated 9 December 1939, the current need at the time was 24 more planes of a type that had the same abilities as the Fokker C.X. - "Ilmavoimien sodanaikainen lentokonetarve ja sen täydennys"
Kaukotoiminta. [...] Nykyhetken tarve on täten 2 laivuetta = 24 konetta, joiden hankinta on ensisijaisen tärkeä. Näiden koneiden ei tarvitse olla varsinaista pommikonetyyppiä, vaan olisi n. 200 kg. kuljettava, nopea ja ketterä, 90 asteen syöksypommitukseen pystyvä tiedustelukonetyyppi, jopa edullisempikin.

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Juha Tompuri
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Re: Technical handicap of Finnish Air Force?

Post by Juha Tompuri » 30 Sep 2014 20:16

Mangrove wrote:According to a Finnish Air Force memo dated 9 December 1939, the current need at the time was 24 more planes of a type that had the same abilities as the Fokker C.X. - "Ilmavoimien sodanaikainen lentokonetarve ja sen täydennys"
Kaukotoiminta. [...] Nykyhetken tarve on täten 2 laivuetta = 24 konetta, joiden hankinta on ensisijaisen tärkeä. Näiden koneiden ei tarvitse olla varsinaista pommikonetyyppiä, vaan olisi n. 200 kg. kuljettava, nopea ja ketterä, 90 asteen syöksypommitukseen pystyvä tiedustelukonetyyppi, jopa edullisempikin.
I think the memo means long distance range planes, like Blenheims were.
And I think C.X. wasn't that fast. Agile? Was it used at 90deg dive bomber?
More likely I read it as a promotion of (surprise, surprise) another Fokker - G.1.

Regards, Juha

Juha
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Re: Technical handicap of Finnish Air Force?

Post by Juha » 30 Sep 2014 21:42

Juha Tompuri wrote: ...Was it used at 90deg dive bomber?..
Seems to be, at least in one combat report a pilot wrote that because the dive angle went over 90deg he was unable to bomb the target.

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Re: Technical handicap of Finnish Air Force?

Post by Juha » 30 Sep 2014 21:53

D-XXI was a good climber, unfortunately I-153 and I-16 Type 18 were clearly better and Type 10 as good as D.XXI. Fokker also dived well and if there was enough height, it could disengage by diving.
Hawk 75A had very good aileron control and was good in horizontal plane and was also very robush plane. Max flight time appr. 3 hours.

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Juha Tompuri
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Re: Technical handicap of Finnish Air Force?

Post by Juha Tompuri » 01 Oct 2014 20:40

Juha wrote:
Juha Tompuri wrote: ...Was it used at 90deg dive bomber?..
Seems to be, at least in one combat report a pilot wrote that because the dive angle went over 90deg he was unable to bomb the target.
Thanks, I've (earlier) been under the impression that they were trained and used as glide bombers.

Regards, Juha

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Juha Tompuri
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Re: Technical handicap of Finnish Air Force?

Post by Juha Tompuri » 01 Oct 2014 20:54

Juha wrote:Fokker also dived well and if there was enough height, it could disengage by diving.
But IIRC the max diving speed (because of the fragile structure?) being rather modest.

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Re: Technical handicap of Finnish Air Force?

Post by Juha » 02 Oct 2014 21:15

Juha Tompuri wrote:But IIRC the max diving speed (because of the fragile structure?) being rather modest.

Regards, Juha
D. XXI was a robush plane but draggy, it could make 90deg long dive safely but couldn't reach high diving speed because its, cannot remember the right term but lets say that after it reahed its "terminal speed" it couldn't accelerate any more.

Juha

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Juha Tompuri
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Re: Technical handicap of Finnish Air Force?

Post by Juha Tompuri » 03 Oct 2014 22:26

Juha wrote:
Juha Tompuri wrote:But IIRC the max diving speed (because of the fragile structure?) being rather modest.

Regards, Juha
D. XXI was a robush plane but draggy, it could make 90deg long dive safely but couldn't reach high diving speed because its, cannot remember the right term but lets say that after it reahed its "terminal speed" it couldn't accelerate any more.

Atso Haapanen at Suomen Ilmavoimien hävittäjähankinnat 1918 - 1945 mentions the max diving speed (AFAIK power dive) deing of 547km/h

Regards, Juha

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Re: Technical handicap of Finnish Air Force?

Post by Seppo Koivisto » 04 Oct 2014 18:34

According to Lentäjän näkökulma II by Raunio, page 85, the dive speed of FR-79 with skis was tested on 11 April 1938 with the following results:
45 degrees dive; speed of 385 km/h was reached in 25 seconds with the loss of 1300 meters of altitude.
60 degrees dive; speed of 440 km/h was reached in 20 seconds with the loss of 1600 meters of altitude.
90 degrees dive; speed of 470 km/h was reached with the loss of 2000 meters of altitude.
In prolonged dives the max. speed of 480-485 km/h was reached.

As the Fokker D.XXI had a ground adjustable prop, the prop setting could affect the power setting you can use in a steep dive without over reving the engine. Maybe with combat prop setting the speeds would be even lower than with the test prop setting.

durb
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Re: Technical handicap of Finnish Air Force?

Post by durb » 04 Oct 2014 20:06

I have read recently that Richard Lorenz test-flew Fokker D XXI in 1936 before the purchase decision was made. IIRC, he viewed Fokker D XXI favourably. I guess that Fokker D XXI was a decent plane by 1936 standards and by that time something was needed quickly to replace Gamecocks and Bulldogs.

The Fokker D XXI had also some advantages when it came to maintenance. It was a robust and simple plane, easy for mechanics to handle in rudimentary conditions like in icelake bases. My guess is that fixed landing gear and possibility to use skis was a seen as a strength for rough field conditions. Retractable landing gears were still very new thing in 1936, when the long term decision of FAF fighter purchase was made. After that it was difficult to change the chosen fighter. Fiat G 50 was not a ideal for Finnish winter conditions, but it was the only available modern fighter for FAF in autumn 1939 (with short delivery time).

Fokker made it quite well in Winter War. Of course Brewsters (or Hurricanes) would have made it even better, but sadly they were not available until March 1940. Dutch claim that Fokker D XXI had some success against Luftwaffe in May 1940 - I´m not sure, but they reportedly managed to shoot down even few Bf 109 or Bf 110 and dived successfully after Stukas.

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