P!mp my Blenheim

[tomo pauk]

Perhaps it might have been more sensible to upgrade and/or refine the Bristol Blenheim than to produce some of other British 2-engined aircraft? Here is the chance

 

[Shortround6]

I certainly think much more effort could have been put into the Blenheim for an improved return at little increase in cost.

Please note this is more from a reduced accident rate, improved survival rate than any great increase in speed or weapons load.

1. change the propellers.
2. put clam shell doors on the landing gear and not the apron doors.
3. Fix/relocate some the controls in the cockpit.
4. perhaps expand the vertical fin a bit?

For weapons,
1. after the first few dozen belly pack gun trays redesign the thing so it doesn't look like something teenage apprentice railroad wagon makers built.
2. stick a gimbaled K gun in the nose much like the Beauforts twin mount.
3, see if there was any possibility of increasing the bomb load on the MK IV? Even at a cost in range.

 

[tomo pauk]

Some data sheets, kindly provided by Neil Stirling:

 

[Snautzer01]

Stick some guns underwing that will lob a shell through a panzer 1 to 3. Yes a hs129. Fast and manouvrable it will kill the german 3 rd armee in its tracks. No Duinkerken, no breakthrough un attended.

 

[tomo pauk]

<snip>
3, see if there was any possibility of increasing the bomb load on the MK IV? Even at a cost in range.

We can see in the data sheets that tare weight went up by about 1700 lbs from Mk.I to Mk.IV, and then another 1000 lbs from Mk.IV to the Mk.V. The max weight went up 3300 lbs, and then by another 1240 lbs for the same aircraft. Granted, some of that weight was due to the additional fuel tanks fitted, change in fuselage, added protection for crew, and MGs increase from two to five.
Having 100 imp gals of fuel less equals 720 lbs, plus whatever weight is saved by removing a fuel tank. Being allowed for 1720 lbs of war load and still having 370 imp gals of fuel still means 1000+ miles of range even if the additional war load is hung into breeze?

 

[Kevin J]

Perhaps it might have been more sensible to upgrade and/or refine the Bristol Blenheim than to produce some of other British 2-engined aircraft? Here is the chance

So we cancel the Mosquito, yes?

 

[Kevin J]

Perhaps it might have been more sensible to upgrade and/or refine the Bristol Blenheim than to produce some of other British 2-engined aircraft? Here is the chance

Okay, for the maritime patrol role to replace the Anson, first replace the Mercury with the Perseus. We should have lots spare if we cancel the Botha. Altitude performance not required. No rear turret, just a Beaufighter style dome. Stick four point 303 LMG packages round the front fuselage. Arm it with bombs and depth charges. Targets are Axis merchant shipping, submarines, torpedo boats. Start point is Bristol type 143.

 

[swampyankee]

For submarines, one wants no less than 20 mm, as one would want some chance of penetrating the U-boat's pressure hull. Maybe a 20 mm isn't enough, but the 40 mm "S" gun should suffice.

So a couple of 0.303 in machines to deter the U-boat crew and a 40 mm "S" gun to put a hole in its pressure vessel.

 

[Shortround6]

One of the U-boats ( I forget which one) had 22mm hull thickness. Granted it was not armor but it was a much better grade of steel than surface ship hulls.

The 20mm is going to need divine intervention of the parting clouds, golden rays of light and heavenly chorus accompaniment kind.

The 40mm isn't going to do much better. The navy settled on a 4in gun on their escorts as they found that 3in or 12pdr guns would not reliably pierce a U-boat hull.
U-boats are low in the water, the pressure hull is round and at best (unless really lucky with the waves) you are going to get a glancing hit on the curve of the hull.
The British 6pdr AT gun would go through more armor than the 75mm gun on a Sherman tank which is why it worked in the Mosquito.

If you are close enough to take pot shots with a 40mm gun (rate of fire under 2 rounds per second) you are close enough to fly over the sub and drop a string of 250 anti-sub bombs or depth charges.

This is one thing that makes the Blenheim a much more effective Coastal Command aircraft than the Anson. The ability to actually kill the U-boat rather than just annoy it even if the chances of a kill are low. The higher cruise speed and longer endurance also mean more hours on each mission in the patrol area or escorting the convoy rather than flying to and from the duty area.

the "improved" Blenheim is not a war long solution, just a 1 -2 year "fix" while even better aircraft are developed and brought in (or transfered from Bomber command as the 4 engine planes show up).

Improved Blenheims could also take on other roles but given the low power of the engines each role is going to require a special version and not a one plane fits all roles solution.

 

[Shortround6]

replace the Mercury with the Perseus. We should have lots spare if we cancel the Botha. Altitude performance not required

No need for the Sleeve Valve kool-aid, The Mercury XII offered 830hp for take-off and 890hp at 6000ft on 87 octane fuel. You do loose the speed up high but for Coastal Command work it might have done OK.
Later Blenheims were Allowed to use 9lbs boost with 100 octane fuel which pretty much solved the power problem at low altitudes without changing the supercharger/gears.

 

[swampyankee]

One of the U-boats ( I forget which one) had 22mm hull thickness. Granted it was not armor but it was a much better grade of steel than surface ship hulls.

The 20mm is going to need divine intervention of the parting clouds, golden rays of light and heavenly chorus accompaniment kind.

The 40mm isn't going to do much better. The navy settled on a 4in gun on their escorts as they found that 3in or 12pdr guns would not reliably pierce a U-boat hull.
U-boats are low in the water, the pressure hull is round and at best (unless really lucky with the waves) you are going to get a glancing hit on the curve of the hull.
The British 6pdr AT gun would go through more armor than the 75mm gun on a Sherman tank which is why it worked in the Mosquito.

If you are close enough to take pot shots with a 40mm gun (rate of fire under 2 rounds per second) you are close enough to fly over the sub and drop a string of 250 anti-sub bombs or depth charges.

More bombs are the solution, then.

I do remember reading that several MPA had 20 mm installed in the hope of actually damaging the submarine, as opposed to scratching the paint. I was thinking the 57 mm would be too much weapon for a Blenheim to carry without degrading performance too far. Against the U-boat's crew, 0.303 in MG should be enough to wreck their day.

 

[Kevin J]

One of the U-boats ( I forget which one) had 22mm hull thickness. Granted it was not armor but it was a much better grade of steel than surface ship hulls.

The 20mm is going to need divine intervention of the parting clouds, golden rays of light and heavenly chorus accompaniment kind.

The 40mm isn't going to do much better. The navy settled on a 4in gun on their escorts as they found that 3in or 12pdr guns would not reliably pierce a U-boat hull.
U-boats are low in the water, the pressure hull is round and at best (unless really lucky with the waves) you are going to get a glancing hit on the curve of the hull.
The British 6pdr AT gun would go through more armor than the 75mm gun on a Sherman tank which is why it worked in the Mosquito.

If you are close enough to take pot shots with a 40mm gun (rate of fire under 2 rounds per second) you are close enough to fly over the sub and drop a string of 250 anti-sub bombs or depth charges.

This is one thing that makes the Blenheim a much more effective Coastal Command aircraft than the Anson. The ability to actually kill the U-boat rather than just annoy it even if the chances of a kill are low. The higher cruise speed and longer endurance also mean more hours on each mission in the patrol area or escorting the convoy rather than flying to and from the duty area.

the "improved" Blenheim is not a war long solution, just a 1 -2 year "fix" while even better aircraft are developed and brought in (or transfered from Bomber command as the 4 engine planes show up).

Improved Blenheims could also take on other roles but given the low power of the engines each role is going to require a special version and not a one plane fits all roles solution.

On the other hand, the 40 mm cannon would make a fair bit of a mess of German torpedo boats, so maybe a 40 mm cannon sticking out the nose, a couple of depth charges behind it in the rear bomb bay and two 250 lb bombs under the wings. If attacking a sub aim for the conning tower or gun crew peppering them with LMG fire on the way in, while dropping your bombs and depth charges when you got closer. There was even a case of a Soviet Cobra sinking a German freighter with its cannon fire, so anything is really possible. The 40 mm cannon was first used 1942 in the Western Desert, although I don't see why our up-gunned Blenheim couldn't have been wrecking havoc in the Bay of Biscay in 1941.

 

[tomo pauk]

So we cancel the Mosquito, yes?

No.
There is a lot of other stuff needing cancellation. The two don't use same engines, nor the same material, nor they are made by same company.

 

[Kevin J]

No.
There is a lot of other stuff needing cancellation. The two don't use same engines, nor the same material, nor they are made by same company.

My thoughts on cancellations are the Albemarle, Botha and Hereford which were a complete waste of time and money. What us Brits really lacked were home produced bomber transports, even the Soviets had lots. So more Harrows and Bombays and an earlier introduction of the Short Freighter. I like your idea of a some more useful Blenheim variants.

 

[Shortround6]

On the other hand, the 40 mm cannon would make a fair bit of a mess of German torpedo boats, so maybe a 40 mm cannon sticking out the nose, a couple of depth charges behind it in the rear bomb bay and two 250 lb bombs under the wings. If attacking a sub aim for the conning tower or gun crew peppering them with LMG fire on the way in, while dropping your bombs and depth charges when you got closer. There was even a case of a Soviet Cobra sinking a German freighter with its cannon fire, so anything is really possible. The 40 mm cannon was first used 1942 in the Western Desert, although I don't see why our up-gunned Blenheim couldn't have been wrecking havoc in the Bay of Biscay in 1941.

You are expecting a lot for small engines.

I have no idea why this fascination with the 40mm S gun. Rate of fire was sssllloooooowwww.
It weighed 320lbs so you can stick in two 20mm guns with weight left over for more ammo and have 12 times the number of shots fired per second.

In 1941 you already had Whirlwinds trying shoot up S-boats with four 20mm cannon.

The "improved" Blenheims day in the sun (or moonlight) should have been in 1940-41 and been replaced going into 1942.

My ideas are for a bit more target effect with fewer loses, many of the losses being due to poor propellers, engines not suited for the altitudes being flown, poor cockpit controls, air brakes extending with landing gear and perhaps other things that make single engine flight difficult or impossible.
That and Blenheims were kept on in Bomber Command to keep up numbers when they could have contributed more in other areas, Keeping Ansons on coastal patrol /ant-sub duties until 1941 was a gift to the Germans.

 

[Shortround6]

Interesting write up and pictures about flying a Blenheim in modern air displays.

A History: John Romain & the Bristol Blenheim

Some information on dealing with Mercury engines.

 

[tomo pauk]

Any point in sticking the Merlin on Blenheim, or something else that is more powerful than Mercury on same fuel?
A dive-bomber Blenheim?

 

[Shortround6]

Sticking Merlins on it wouldn't fix most of the problems the RAF had at the time, which had to do with doctrine, training and acceptance of some pretty strange cockpit layouts.

The Blenheim might have made a fairly decent interim torpedo bomber. It wouldn't do what the Beaufort was supposed to do but it would sure do a lot more than the Vildebeest. It might have also helped point out that slowing a 200mph airplane down to 100mph to drop the torpedo wasn't a good idea. Later torpedoes got higher drop limits.

Converting it to a dive bomber is a lot of work for little result. If you want better bombing accuracy get a better bomb sight for medium altitude work and figure out some sort of bomb sight/technique for low altitude work besides pilot pointing the plane at the target and releasing the bombs a little short using just his judgement.
This was part of the RAF failings. Too much emphasis on numbers and not enough on what kind of results or what was needed to get results. Dive bombing only works if you can find the target and most good dive bombers used a sight of some sort.

 

[Shortround6]

Many british aircraft were partially crippled by the poor british bombs.
The standard British 250lb GP bomb was filled with about 67lbs of explosive.
The Germans rather ignored the 100-120kg catagory but the SC-50 bomb carried about 55lbs of explosive and the SD-50 carried 35.2lb
The SC-250 carried 276-287lbs of explosive and the SD-250 carried about 176lbs.
The British 500lb GP bomb carried about 143-146lbs,

I believe (open to correction) it took awhile for the British to introduce MC case bombs with higher percentage of of explosive.

This seems to be something the British had a hard time with. The actual weapon is the bomb, bullet or shell in that they are what does the damage. The gun or airplane is just the delivery system. Great delivery system with poor payload equals mediocre, at best, weapon system.

 

[tomo pauk]

...
Converting it to a dive bomber is a lot of work for little result. If you want better bombing accuracy get a better bomb sight for medium altitude work and figure out some sort of bomb sight/technique for low altitude work besides pilot pointing the plane at the target and releasing the bombs a little short using just his judgement.
This was part of the RAF failings. Too much emphasis on numbers and not enough on what kind of results or what was needed to get results. Dive bombing only works if you can find the target and most good dive bombers used a sight of some sort.

The last sentence holds true for the 'level bombers', too.
The good bomb sight and a bomb aimer well seasoned in the use of the sight are a must, while dive bombing was done with 'normal' sight as found on fighters. Dive bombing was 1st and foremost 'dive at a steep angle and point your aircraft to just over-shoot the target' procedure, obviously followed by tossing the bomb and leveling-out.

For the starters, I'd try with reinforced U/C legs so they can be extended at higher speeds to act as dive brakes.