AHC: replace Bristol Blenheim much earlier

[Just Leo]

Its a possibility - perhaps had Supermarine not been bombed in Southampton?

Also I'm not sure if that's what you meant but the Hispanio Cannon in the French Fighters did not fire through the Hub per se but fired from between the Vee of the Engine using an interrupter gear much like the Bf109

But there would be no need for such a complex fitting if the 4 cannon could go in the nose - which they could!

The Hispano motor cannon was fitted between the cylinder blocks and the barrel protruded through a hollow propeller hub offset by the reduction gear box. It did not require an interrupter gear. It is interesting that the length of the barrel was quite long for the purpose of clearing the hub, and the RAF Mk5 version took advantage of a much shorter barrel with little effect on muzzle velocity.

The Supermarine 313 speed estimate came from a heavy dose of bullshit. Its general arrangement is not dissimilar to the Curtiss YA-18 Shrike which lost out to the A-20 for contract gold, but the Goshawk engine was effectively proven a non-starter. Similar pie-in-the-sky performance estimates were applied to several other Supermarine napkin projects. It's all just whimsy. R.J. Mitchell was dead.

 

[tomo pauk]

The Bf 109 also did not use interrupter gear for it's cannon(s), apart from one off attempt with single gondola MG 151/20E in place of the drop tank.

The 'Twin Battle' (two Merlins) - what it has to offer? Wing is thick so much that it would ashame the Bristol aircraft, same wing span as Blenheim.

 

[Mike D]

The 'problem' wasn't really the Blenhem, it was the RAF's appalling early war mission choices and planning.

You could have Mosquitos in the same role in 1939 and they'd still get slaughtered if they were sent out unescorted to attack targets heavily defended by light flak and fighters at low level.

In 1940, a squadron of 12 Blenheims was dispatched to attack an airfield in the Netherlands. One aborted. The pilot facing court martial for cowardice/LMF died before his hearing, on another mission.

Denmark (an airfield outside Aarlborg) from memory.

 

[tomo pauk]

The French were using DB-7 and (later named) Maryland fast bombers, and suffered only light casualties. So I don't think that a 320-330 mph bomber would've been slaughtered like it was the case for 250 mph Blenheims and Battles. Faster bomber means it is a tougher target for Flak, bigger bomb load improves chances of destruction of designated target.
Sure enough, fighter escort would've been a great thing for Battles and Blenheims, the targets in Belgium were not that far out from RAF fighter bases. Fighter escort was not what RAF was doing well, or doing at all before 1942/43/44, depending on theatre.

 

[Mike D]

The French were using DB-7 and (later named) Maryland fast bombers, and suffered only light casualties.

How well would the Maryland have done taking off from the UK, crossing the North Sea, flying half the length of Denmark and then attacking a target heavily defended by light flak all while being watched by German radar and ground observers?

That's the kind of stupid target choices the RAF was making for their Blenheims in 1940. I seriously doubt any WW2 type would have done much better for survivability under the circumstances the Blenheim was used.

 

[Cryhavoc101]

The Hispano motor cannon was fitted between the cylinder blocks and the barrel protruded through a hollow propeller hub offset by the reduction gear box. It did not require an interrupter gear. It is interesting that the length of the barrel was quite long for the purpose of clearing the hub, and the RAF Mk5 version took advantage of a much shorter barrel with little effect on muzzle velocity.

The Supermarine 313 speed estimate came from a heavy dose of bullshit. Its general arrangement is not dissimilar to the Curtiss YA-18 Shrike which lost out to the A-20 for contract gold, but the Goshawk engine was effectively proven a non-starter. Similar pie-in-the-sky performance estimates were applied to several other Supermarine napkin projects. It's all just whimsy. R.J. Mitchell was dead.

I stand corrected

But the arrangement is unnecessary if you can fit the cannon in the nose of the aircraft - easier to service and rearm etc.

Although replacing the nose area with a bomb aimer position would of course make shifting the cannon somewhere else - possibly the hub firing arrangement - a better idea.

 

[tomo pauk]

Hello, Mike D,

The Mosquitoes were doing just the scenario you've described.

 

[yulzari]

The Blenheim was a generation just before the alternatives suggested. At the time of it's introduction it was a fast medium day bomber that could outrun most contemporary fighters. In operations against the Italians in Albania they coped with the opposition of similar quality.
The production lines existed when the RAF was being enormously expanded. To stop production to make something else would leave new squadrons armed with it's predecessors not it's successors.
It is tempting to take the Merlins off the Battles but you run into the same situation. Light day bomber squadrons flying Harts. A better Battle would have been more Hurricanes with a bomb rack but that is OTL 20/20 hindsight and you still need a Blenheim replacement as there will not be enough Merlins for a Battle and a Blenheim replacement.

The warload of a Blenheim is 1,000lb. The same as the Battle. This is easily carried with 1,600bhp such as with two Mercuries. Bristol was incapable of making any of it's sleeve valve engines in quantity at the time and was flat out with the Pegasus for Hampdens, Sunderlands and Wellingtons. Rolls Royce was flat out with the Merlins as IOTL. The possibilities are Bristol's Mercury or Napier's Dagger. Just possibly the Tiger.

The customer at that time wanted a pilot, navigator and a gunner in a turret so that has to be dragged about. The customer will also want the craft to be able to use small grass fields so a low wing loading is required by them. Now we would not ask for such things but, at that time, it was thought necessary.

Now we can understand why the Blenheim continued. For the power available from two Mercury engines and with the necessary crew and range with a low wing loading it was as good as you were going to get.

So I would revise the question to, what POD in Air Ministry thinking would let you deliver 1,000lb of bombs in daylight better using either Bristol Mercuries or Napier Daggers? Even the Hawker Henley only carried 500lb in it's bomb bay.

What was needed was not an alternative Blenheim in the same timescale but a next generation that could be in full production to equip these new RAF squadrons. Foreign made engines and airframes were supplements. The RAF had to be planned around UK made engines and airframes for security of supply. Ideally it would merge with the same need for a Battle replacement and, just possibly, a FAA strike need.

 

[Mike D]

Hello, Mike D,

The Mosquitoes were doing just the scenario you've described.

Much later in the war, against a weakened Luftwaffe, with far more thought put into their attacks, carried out with crews with far better training.

 

[tomo pauk]

Also against reasonable radar network, visual coverage in all of the West Europe, the 400 mph fighters, and twice as numerous Flak.

 

[galveston bay]

I've never figured out why the USAAF did not use the Martin Maryland or the Martin Baltimore. Both were very good planes the RAF and SAAF seemed to like them.

because the B25 and B26 where better

 

[Driftless]

I wonder why so few of the twin engined Martins were used by the RAF? The production line for the 167s was operating, and projected output for 1941 was 1200+. The existing July delivery was commandeered by the Brits. Some stripped models were used for high altitude/long range reconissance. Instead Havocs and Mauraders were ordered from the US.

I've never figured out why the USAAF did not use the Martin Maryland or the Martin Baltimore. Both were very good planes the RAF and SAAF seemed to like them.

because the B25 and B26 where better

I'd think a big part of it was timing of availability.

Martin Maryland: First Flight - Mar 1939, in service early 1940
Martin Baltimore: First Flight - June 1941, in service later 1941
Douglas DB-7: first Flight - Jan 1939, in service Jan 1941
NA B-25: First Flight - late Aug 1940, in service Feb 1941 - but early revisions followed before it was ready for "prime time"
Martin B-26: First Flight - Nov 1940, in service Feb 1941 but the learning curve was steep.

During 1939/40 the British & French needed useful aircraft quickly, the US could afford to wait on the potential of the B-25 & B-26

B-25 tidbit

In 1939, the modified and improved NA-40B was submitted to the United States Army Air Corps for evaluation. This aircraft was originally intended to be an attack bomber for export to the United Kingdom and France, both of which had a pressing requirement for such aircraft in the early stages of World War II. However, those countries changed their minds, opting instead for the also-new Douglas DB-7 (later to be used by the U.S. as the A-20 Havoc). Despite this loss of sales, the NA-40B re-entered the spotlight when the Army Air Corps evaluated it for use as a medium bomber. Unfortunately, the NA-40B was destroyed in a crash on 11 April 1939. Nonetheless, the type was ordered into production, along with the Army's other new medium bomber, the Martin B-26 Marauder.

 

[Just Leo]

The 'problem' wasn't really the Blenhem, it was the RAF's appalling early war mission choices and planning.

You could have Mosquitos in the same role in 1939 and they'd still get slaughtered if they were sent out unescorted to attack targets heavily defended by light flak and fighters at low level.



Denmark (an airfield outside Aarlborg) from memory.

I think you're right.

And, OOPS.

One thing lacking in doctrine was an offensive fighter policy. Someone gave it a thought but the result of that thought was the misbegotten Whirlwind, delayed by choice of dead-end engine and lack of interest. The planned escort fighter morphed into an attack fighter bomber, of the type it was intended to defend. Curiously, the Whirlwind's armament was 4 cannons, selected for future use based on field testing against a Blenheim's armor and self-sealing fuel tanks. Later, the Luftwaffe verified those findings.

 

[tomo pauk]

I don't think that Whirly was ever designed as an escort fighter. It was a winning proposal for a requirement that asked for a fighter with very heavy firepower and high speed, basically a next-gen interceptor fighter. Total of 134 imp gals for total of 1750+ HP won't cut it for long range work; fuel system did not have cross feed needed when one engine is out.
It is really too bad Westland/Peter designed it around wrong RR engines.

RAF FC did not have a desire for escort fighter, their job in interwar period was air defence of UK.

 

[Just Leo]

I don't think that Whirly was ever designed as an escort fighter. It was a winning proposal for a requirement that asked for a fighter with very heavy firepower and high speed, basically a next-gen interceptor fighter. Total of 134 imp gals for total of 1750+ HP won't cut it for long range work; fuel system did not have cross feed needed when one engine is out.
It is really too bad Westland/Peter designed it around wrong RR engines.

RAF FC did not have a desire for escort fighter, their job in interwar period was air defence of UK.

I agree that the RAF didn't want an escort fighter because they never planned for it, but the Air Ministry did mouth the term. But talk is cheap. They didn't plan everything just as it turned out. However, as late as Feb 1944, Hawker Typhoons were escorting Mossies on Operation Jericho, and Typhoons were a failed fighter with as many flaws as the Whirly, but more power. They carried 150 gal., and had much the same range or less.

PS; the name's Petter. Arthritis will do that to ya.

 

[riggerrob]

Mosquitos' wooden airframes were transparent to radar. Mossies only reflected radar waves went water-logged.

Meanwhile Blenhiem's all aluminum airframe provided great primary return of radar waves.
A related question is how large a radar blip did fabric-covered airframes present?
Fabric-covered metal frames aka. Wellington?
Were they painting fabric with aluminum powder impreganted dope back in 1939?
How big a blip (primary target) was reflected by aluminum-doled fabric on wood frames?

 

[tomo pauk]

There are still 2 engines, together with radiators and with two props turning. Radars of the era did not have problems detecting small aircraft like Bf 109. Later even the midget V1 flying bombs, and, as early as Italy landings even smaller battleships shells. We can recall that Mosquitoes were flying very much at treee top/wave top during daylight missions, better safe vs. radars than sorry.

Hi, Just Leo,
The Typhoon was outfitted with 2 drop tanks before too late, a luxury that Whirly never acquired. Amiens, in Norther France, was closer than Brussels when flying from Kent.
For escort against Ruhr, staged and ending in England, it will need considerably more fuel, both internal ans external. Something along the lines of what Tempest got by the end of 1944 - some 190 imp gals internally, plus 2 x 90 in drop tanks. For escort in deep Germany, maybe 250 imp gals plus similar volume of external fuel?

Thanks for the tip re. Petter.

 

[marathag]

Mosquitos' wooden airframes were transparent to radar. Mossies only reflected radar waves went water-logged.

Meanwhile Blenhiem's all aluminum airframe provided great primary return of radar waves.
A related question is how large a radar blip did fabric-covered airframes present?
Fabric-covered metal frames aka. Wellington?
Were they painting fabric with aluminum powder impreganted dope back in 1939?
How big a blip (primary target) was reflected by aluminum-doled fabric on wood frames?

That's the problem. Al powder was added to almost all Dope by the '20s, for UV protection for both fabric and wooden stringers.

But don't understate the return you get from two big rotating metal propellers attached to two big engines with large reduction gear sections for supercharging. Then add in metal fuel tanks and Radiators

The Mossie was good from its shape/small cross section, not from it being wood.

 

[Just Leo]

I'd think a big part of it was timing of availability.

Douglas DB-7: first Flight - Jan 1939, in service Jan 1941

According to a source, 64 AdA DB7s were in service on May 10, 1940. They flew 70 sorties and lost 8 before they were withdrawn because they could cross the Med.

 

[Driftless]

According to a source, 64 AdA DB7s were in service on May 10, 1940. They flew 70 sorties and lost 8 before they were withdrawn because they could cross the Med.

I scooped that Jan 1941 off the Wiki insert - so the precision is suspect. The earlier date makes sense