Bristol Blenheim

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Vaeltaja
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Re: Blunders of Finnish Military

Post by Vaeltaja » 25 Aug 2010 08:43

Surely fastest of its class and better construction than Tupolev SB. It had three hundred horsepowers more per engine and still was slower and less maneuverable than Blenheim.
Nope.. Not the fastest any longer at that time. Blenheim was the fastest in mid 1930s. By 1939 it was no longer fast nor was it exceptional in any other sense. As for it being better construction than Tupolev SB. Not sure if it was better (depending on how it is rated) but it appears to have been aerodynamically 'cleaner' design than SB, more economic being able to reach comparable speed and load with far less engine power (which might have contributed to its acclaimed diving speeds).
Posts at the target are only useful on fair weather, not in typical Winter War weathers when the bombers were spotted five minutes before the bombs were dropped. There were no fighters in the whole world in 1939 which could intercept these bombers in that time. According to post-war study, made by A. Lassila of HLe.Lv.31, it took between one and a half and two minutes for a Bf 109 to takeoff in winter condinitions. Add three, four minutes for a typical fighter to climb to 3000 meters and the bombs are gone!
True. And obsolescent design like Fokker D XXI required even more time.The delays from detection via ground control to eventual scramble always cost valuable time which Fokker with its slow flight speed was unable to regain. Karhunen describes several occasions when fighters were scrambled (near Turku apparently) and even saw the departing bomber formation but was unable to catch the bombers and attack. That is to say that with even slightly better performance interceptors the ground control lead interception might have worked adequately. For Fokker D XXIs its response rate was too slow.

Mangrove
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Re: Blunders of Finnish Military

Post by Mangrove » 25 Aug 2010 10:00

Vaeltaja wrote: Nope.. Not the fastest any longer at that time. Blenheim was the fastest in mid 1930s.
If you like you could point out a light bomber type which was faster and better than Blenheim in 1939. "TNL" provides Sukhoi Su-2 as 460 km/h at 5.200 meters, but the type had only mediocre load, 200-600 kg.
Vaeltaja wrote: Not sure if it was better (depending on how it is rated) but it appears to have been aerodynamically 'cleaner' design than SB, more economic being able to reach comparable speed and load with far less engine power (which might have contributed to its acclaimed diving speeds).
For starters SB crews used notes to pass information as there were no internal radios on the plane. Second the plane did not have self-sealing tanks as Finnish Blenheims had. The M-103s on Tupolev overheated often. On the good side "TNL" attributes good glide ratio ("liukukyky hyvä") to the type.

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Re: Blunders of Finnish Military

Post by Vaeltaja » 25 Aug 2010 11:55

Tupolev SB-2 had comparable top speed and load as had Dornier Do 17Z & Do 215. All which were classified as light bombers. Some bit obscure or rare designs like Yak-2 or Bloch MB.170 were even faster with only marginally smaller bomb load. Douglas A-20 (or as was in French use DB-7B) was introduced only slightly after the Winter War but had completely superior performance to either. Polish PZL.37 Łoś, Heinkel He 111H, Ilyushin DB-3, Savoia-Marchetti SM.79 and Handley Page Hampden were bombers or medium bombers instead of light bombers but all had comparable performance to Blenheim - apart from bomb load which could be several times as high depending on type. Just how many you want there to be listed?

Instead as so nicely put in http://en.wikipedia.org/wiki/Bristol_Blenheim which pretty much sums it up.
The Blenheim was regarded as a pleasant aircraft to fly, although it did have some characteristics which could catch even experienced pilots by surprise. Unfortunately, with the rapid advances in technology which had taken place in the late 1930s, by the start of the Second World War, the Blenheim was obsolescent. The aircraft had become heavier as extra service equipment was installed; much of this was found to be needed through operational experience. This, coupled with the rapid performance increases of fighters, had eclipsed the Blenheim's speed advantage.

Mangrove
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Re: Blunders of Finnish Military

Post by Mangrove » 25 Aug 2010 13:30

Vaeltaja wrote:Tupolev SB-2 had comparable top speed and load as had Dornier Do 17Z & Do 215. All which were classified as light bombers. Some bit obscure or rare designs like Yak-2 or Bloch MB.170 were even faster with only marginally smaller bomb load. Douglas A-20 (or as was in French use DB-7B) was introduced only slightly after the Winter War but had completely superior performance to either. Polish PZL.37 Łoś, Heinkel He 111H, Ilyushin DB-3, Savoia-Marchetti SM.79 and Handley Page Hampden were bombers or medium bombers instead of light bombers but all had comparable performance to Blenheim - apart from bomb load which could be several times as high depending on type. Just how many you want there to be listed?
That's just plain rubbish. Let me illustrate that with this list, data by Raunio & "TNL":
Speed:
Blenheim: 435 km/h (Mk. I), 450 km/h (Mk.IV)
DB-3M: 408 km/h (M-85), 437 km/h (M-87/88)
Hampden: 427 km/h
Do 17Z: 425 km/h
SB-M-103A: 385 km/h

Bomb load:
DB-3M: c. 1.500 kg (racks for 2.000 kg).
Hampden: 1.500 kg.
SB-M-103A: 1.000 kg.
Do 17Z: 1.000 kg.
Blenheim: 972 kg.

Empty weight:
Do 17Z: c. 5.900 kg
SB-M-103A: 5.534 kg
Hampden: 5.350 kg
DB-3M: 5.270 kg
Blenheim: 4.126 kg (Mk.I), c. 4.500 kg (Mk. IV)

As you can see Blenheim was the fastest, lightest and had the around same bomb load as SB and Do 17. SB's top speed is not even near the one of Do 17! Medium bombers like DB-7 would have been nice, but they were too large for Finnish aerodromes (900-950 meters of runway insted of Blenheim's 550 m).

Vaeltaja
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Re: Blunders of Finnish Military

Post by Vaeltaja » 25 Aug 2010 14:02

Let's see

Blenheim
  • Your source: 450 kph (IV)
  • airwar.ru: 428 kph (IV)
  • en-wiki: 428 kph (IV)
  • militaryfactory.com: 428 kph (IF)
SB-2
  • Your source: 385 kph (M-103)
  • airwar.ru: 450 kph (M-103)
  • en-wiki: 450 kph (M-103)
  • militaryfactory.com: 410 kph (M-100)
Do 17
  • Your source: 425 kph (Z)
  • airwar.ru: 410 kph (Z)
  • en-wiki: 427 kph (Z-2)
  • militaryfactory.com: 410 kph (Z ?)
DB-3
  • Your source: 437 kph (M-87)
  • airwar.ru: 439 kph (B /w М-87А)
  • en-wiki: 439 kph (M-87)
  • militaryfactory.com: 410 (only data for Il-4 with M-88)
Hampden
  • Your source: 427 kph
  • airwar.ru: 426 kph
  • en-wiki: 410 kph
It seems like your opinion (or rather the opinion of your source) that Blenheim would have been fastest does not appear to be so. It seems to be fairly average. And other sources in general seem to state that SB-2 with M-103 engines had top speed of 450 kph.

Mangrove
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Re: Blunders of Finnish Military

Post by Mangrove » 25 Aug 2010 14:56

Vaeltaja wrote: It seems like your opinion (or rather the opinion of your source) that Blenheim would have been fastest does not appear to be so. It seems to be fairly average. And other sources in general seem to state that SB-2 with M-103 engines had top speed of 450 kph.
I just have to point out that your sources are also rubbish. I'm using primary and secondary sources which are generally far superior than tertiary sources you're using. I've test flight reports to back up my point of view, you've got nothing. Those higher readings for SB might be based on factory specifications, not real life tests.

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Slon-76
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Re: Blunders of Finnish Military

Post by Slon-76 » 25 Aug 2010 15:40

Martti Kujansuu wrote:
Vaeltaja wrote: It seems like your opinion (or rather the opinion of your source) that Blenheim would have been fastest does not appear to be so. It seems to be fairly average. And other sources in general seem to state that SB-2 with M-103 engines had top speed of 450 kph.
I just have to point out that your sources are also rubbish. I'm using primary and secondary sources which are generally far superior than tertiary sources you're using. I've test flight reports to back up my point of view, you've got nothing. Those higher readings for SB might be based on factory specifications, not real life tests.
And still in attitude SB you in this case are not right.

Results of tests serial SB (M. Maslov + V. Shavrov):

SB #221 M-100 750 hp (1936) - 393 km/h H-5200 m, bomb 500 kg
SB #22200 M-100A 850 hp (1937) - 423 km/h H-4000 m, 600 kg
SB #1/83 M-103 960 hp (1938) - 419 km/h H-4000, 1500 kg
SB #13/221 M-103U 960 hp (1939) - 450 km/h H-4100 m, 1500 kg

Certainly, speed while in service could will decrease, but all the same not on 40-70 km/h. Thus, Blenheim and SB enough close machines under characteristics.

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Slon-76
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Re: Blunders of Finnish Military

Post by Slon-76 » 25 Aug 2010 15:52

Vaeltaja wrote:Well... I wouldn't consider Blenheim to be unique in any aspect by the 1939. It was fast bomber in the mid 1930s but by the end of the 1930s Blenheim was turned from a fast bomber into a light bomber.
What problems? I also did not speak, that Blenheim - the "wunderwaffe". But nevertheless, it has very not bad consulted with the role in winter war. What sense to compare it with SB? Finns could buy SB? It needs to be compared to the Soviet fighters, and on their background it looks rather not poorly. On speed it has been comparable with I-16 and at competent tactics of application could operate rather unpunishedly. In all cases when the Soviet fighters during winter war managed to force down Finnish Blenheims, it was result of a casual meeting in air. Never to intercept a bomber on an alarm signal it was possible.

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Juha Tompuri
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Re: Blunders of Finnish Military

Post by Juha Tompuri » 25 Aug 2010 18:46

Vaeltaja wrote:Let's see

Blenheim
  • Your source: 450 kph (IV)
  • airwar.ru: 428 kph (IV)
  • en-wiki: 428 kph (IV)
  • militaryfactory.com: 428 kph (IF)
Be that as it may - SB-2 has been listed as having that 450 km/h for example here http://www.airwar.ru/bomberww2.html - there is zero credibility to the claim that Blenheim would have been a fast bomber at that time.
Accidentaly or in purpose:
If you rely and post airwar.ru and it's numbers, why not to post the max speed of Blenheim MkI:
Максимальная скорость , км/ч 459
http://www.airwar.ru/enc/bww2/blenh.html
"Information not shared, is lost" as the Forum motto goes
Slon wrote:I do not think, that Wiikipedia is very authoritative source.
http://forum.axishistory.com/viewtopic. ... t#p1427404
Me neither.

Regards, Juha

Vaeltaja
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Re: Bristol Blenheim

Post by Vaeltaja » 25 Aug 2010 19:01

Yes, Blenheim I was claimed in airwar.ru to be able to fly at 459 kph. But i left it out due a reason... http://users.cyberone.com.au/clardo/bri ... eim_i.html
The fabled top speed of 307 mph (and more realistically, of 285 mph with maximum load) were in fact those achieved by Britain First, and in its as-delivered condition. Mischievously, Jane's 1938 edition quoted the latter as the Type 142M/Blenheim I top speed, often re-quoted since, alongside the equally unattainable 295mph for the Mark IV.
...
Maximum speed:
Variously quoted. 265mph at 10,000 ft.
Vne quoted as 285mph or 287mph
Well.. If we agree that Blenheim and SB-2 had roughly comparable performance and that I-16 (not actually sure which I-16s were used in Winter War) had higher top speed than what Fokker D XXI had (at least according to Finnish pilots it was so). Then Soviet I-16s should have had better chance of taking chasing and taking down Finnish Blenheims than what Finnish Fokker had chance of chasing down and dropping SB-2s.

True enough that wikipedia not very authoritative source. It however is accessible without undue fuss unlike many other sources.

And thanks for cutting the Blenheim discussion into separate thread.

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Juha Tompuri
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Re: Bristol Blenheim

Post by Juha Tompuri » 25 Aug 2010 19:47

Vaeltaja wrote:Yes, Blenheim I was claimed in airwar.ru to be able to fly at 459 kph.
As SB-2 is there mentioned to be capable of 450 km/h.

Vaeltaja wrote:Well.. If we agree that Blenheim and SB-2 had roughly comparable performance
According to what I have read and the tables of Slon, Blenheims seems to have been faster than average SB-2's at Winter War.

Vaeltaja wrote:and that I-16 (not actually sure which I-16s were used in Winter War) had higher top speed than what Fokker D XXI had (at least according to Finnish pilots it was so).
Depending of the undercarriage - might have been slightly faster.
Vaeltaja wrote: Then Soviet I-16s should have had better chance of taking chasing and taking down Finnish Blenheims than what Finnish Fokker had chance of chasing down and dropping SB-2s.
From what I have read the chances might have been quite equal, exept for the poorer diving characteristics of the I-16's.

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Vaeltaja
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Re: Bristol Blenheim

Post by Vaeltaja » 25 Aug 2010 19:59

I guess i didn't say it clearly enough... The often quoted top speed of Blenheim I of 450 or more (459) comes from the value gained with the original Britain First 'Blenheim', which was not equipped as a bomber. That has been stated in several places.

In other words... 285 mph (~ 458,66 kph) was the top speed of the civilian non-militarized prototype while as said in several places the actual top speed of equipped Blenheim I bomber was 265 mph ( ~ 426 kph ).

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Juha Tompuri
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Re: Bristol Blenheim

Post by Juha Tompuri » 25 Aug 2010 20:34

Vaeltaja wrote:I guess i didn't say it clearly enough... The often quoted top speed of Blenheim I of 450 or more (459) comes from the value gained with the original Britain First 'Blenheim', which was not equipped as a bomber. That has been stated in several places.
You said it clearly enough - if you trust on the airwar.ru you can't cherry-pick just the numbers that suit to your opinion.

Vaeltaja wrote:In other words... 285 mph (~ 458,66 kph) was the top speed of the civilian non-militarized prototype
Also your http://users.cyberone.com.au/clardo/bri ... eim_i.html source mentions that the max speed of a full loaded Blenheim MKI being 279 mph (~449km/h)
Vaeltaja wrote:while as said in several places the actual top speed of equipped Blenheim I bomber was 265 mph ( ~ 426 kph ).
Several places?
I seem to trust on the Finnish flight tests (Do you?):
Martti wrote:BL-121 did 435 km/h at 4000 meters and 377 km/h at 0 m, both with 5460 kg. Planes equipted with Mercury XV could archive c. 450 km/h.
http://forum.axishistory.com/viewtopic. ... 1&start=15

Regards, Juha

Vaeltaja
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Re: Bristol Blenheim

Post by Vaeltaja » 25 Aug 2010 20:51

I seem to trust on the Finnish flight tests (Do you?)
After seeing Finnish flight test result of SB-2s.. Nope, not really.

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Juha Tompuri
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Re: Blunders of Finnish Military

Post by Juha Tompuri » 25 Aug 2010 21:00

Martti Kujansuu wrote:
Vaeltaja wrote: Hmm.. Not sure which are real data...
From en-wiki.. Blenheim 540 kg, Fokker C X 400 kg.
From fi-wiki.. Blenheim 526-972 kg, Fokker C X 400 - 600 kg.
These are the largest loads I could find from the original mission reports.
http://digi.narc.fi/digi/fullpic.ka?kuid=2917648 (Blenheim, 6x100 + 2x50 + 2x12,5 = 725 kg)
http://digi.narc.fi/digi/fullpic.ka?kuid=1544290 (C.X, 2x100 + 8x12,5 = 300 kg)
Vaeltaja wrote: Regardless... Values are still roughly in the same ballpark. Difference was that Fokker could deliver the amount with enough accuracy to hit individual fireplaces in the woods as was done in 1942 and that for Blenheim required target size of a city block.
They are not. A 250 kg bomb is not the same as five 50 kg bombs, since it is my understanding the destructive power of the bomb grews by the volume, that is power of three. A 100 kg bomb might not have destroyed those half a dozen tanks that were destroyed by Blenheims on July 4th 1941 at Karelian Isthmus. Fokkers usually had the same targets as Blenheims; convoys, factories, railway stations and such. To really access their success we need Soviet loss data.
The Finnish Blenheim bombload thing is a bit unclear to me, but AFAIK during Winter War the max (theorethical) bombload of the planes with Finnish bombracks was something 900-1000 kg
The ones with English bombracks, 563- or 527 kg

Here a 1941 autumn photo of a Blenheim with mention of (at least) 8 x 100kg bombs
Image http://www.militaryimages.net/photopost ... ppuser/364


Regards, Juha

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