Mosquito rear guns

nuuumannn · Sep 19, 2019

pirate_smee said:
The British air ministry forced De Havilland to install a turret in a mock up, but the speed reduction was significant, so it was droope

The first picture is the installation fitted to the prototype W4050, which was a mock up only for drag trials. Note the holes, through which dummy guns were poked to assess their effect on drag. The second is most likely W4053, the turret fighter prototype fitted with an actual Bristol B.11 turret. Again though, this work was for a dedicated turret equipped night fighter, not for the tail turret equipped bomber. The prototype still has the fittings for the turret buried in its fuselage. As mentioned, two turret fighters were produced, these eventually became the prototypes of the T.III, the third flying prototype W4053 and W4073 and the turret fighter was canned, also because the B.11 turret would not rotate at speed. It's hydraulic system was not up to task.

At the time the first turret fighter Mossie flew, DH had produced the fixed gun night fighter prototype, W4052 and that proved faster, naturally and the decision was made to not progress with the turret fighter variant as a result of the manufacturer's findings regarding the turret not moving at speed. The second turret fighter went from the production line straight to having the turret removed.

nuuumannn · Sep 19, 2019

As an aside, this is a picture of the prototype's cockpit canopy with a rub line, which was from the tunnel fairing installed to close the gap between the turret and the canopy, which without caused a 10 mph loss in speed and buffeting round the turret. Hidden within the structure are four attachment points through which the fittings for the mock up turret were installed.

0507 de Havilland Aviation Heritage Mosquito Prototype turret fairing

The prototype at the excellent De Havilland Aviation Heritage Centre at Salisbury Hall, its birthplace.

0507 de Havilland Aviation Heritage Mosquito prototype

Shortround6 · Sep 19, 2019

JohnL said:
Their was a Aircraft version of the .50 which as cooled by the aircraft's slip-stream, the air-cooled 12.7 mm AN/M2 was fitted with a substantially lighter 36-inch (91 cm) length barrel, reducing the weight of the complete unit to 61 pounds from 83 pounds . So weight of 4 over 300 pounds plus ammo for fifteen seconds so one less 500 pound bomb or not

While the manual for the gun says 61lbs just about every weight and balance chart for US aircraft or just weight charts goes about 71-75lb for each .50 cal gun.
remote cocking devices? Gun heaters? remote firing solenoids? I don't know but this is a constant discrepancy.
.50 cal ammo with links goes about 30lbs per 100 rounds. SInce the .50 AN/M2 fired at around 800rpm your 15 seconds of firing time is 60lbs per gun.

ANd four bare guns and 800 rounds of ammo in pile on the Grass or Pavement is not a weapons system. You need mounts/braces, ammo boxes, chutes/feedways and such. These could add 10-30% more wight over and above the weight of the guns and ammo. Since this installation is in the tail you are going to need eigher ballast or a lot of engineering to get the plane back into balance. You may be giving up two 500b bombs or over 100 gallons of fuel.

Drifter · Sep 20, 2019

JohnL said:
The Mossie avoided losses by outrunning the enemy . So why were streamlined pods not fitted to the rear fuselage say four in each quarter containing a small machine gun (the Browning .50 AN/M2 would be good ) that could fire tracer . Operated by the co pilot and sighted through enhanced rear facing wide and narrow mirrors .
How disconcerted an attacker would have been with four streams of tracer coming at him . So forcing him to evade or be shot down and reducing time could stay on Mossies tail .
In fact on firing this quad mount it would have given the mossie a speed boost . So good idea or ? .

You cant see oncoming tracers, they are only visible from the point of where they are fired from.

Sid327 · Sep 20, 2019

The loss ratio for the unarmed Mosquito types speaks for itself in comparison to other aircraft.

There is much talk of maximum speeds for aircraft.
But surely it's the aircraft with the highest max continuous cruise speed that means much more in this context. And that is what the advantage is for the unarmed versions of the Mosquito.
Why fix something that isn't ''broken.''

JohnL · Sep 20, 2019

Using Headlight ammo mentioned by shortround6 . However as wrote in pre entry Mossie pilot saw Me 262 guns firing from behind so maybe no need for Headlight .
However had a thought reduce weight effect reduce to two .50 machine guns . However mount them inside in the roof just behind bomb bay doors or the cockpit to reduce COG issue. Angled 5 or 10 degress up so firing above rudder and recessed in the roof like cannon in the nose . So reduced weight by half and any drag minimal . Now the pilot when attacked could pull up avoiding the German planes shot , but having his own guns line up to retaliate . Like the Schräge Musik system in the Ju 88 G-6 and Me 110 etc .

Greyman · Sep 20, 2019

Drifter said:
You cant see oncoming tracers, they are only visible from the point of where they are fired from.

Disagree strongly on this one -- based on personal experience and untold number of anecdotes. I'm sure there are exceptions to the rule, but I'd say the vast majority of tracer rounds could be seen from almost every angle.

buffnut453 · Sep 21, 2019

JohnL said:
Now the pilot when attacked could pull up avoiding the German planes shot , but having his own guns line up to retaliate . Like the Schräge Musik system in the Ju 88 G-6 and Me 110 etc .

But pulling up means the Mossie slows down. Given that the odds of hitting an adversary are very low, why would you sacrifice the primary attribute that contributed to low Mosquito loss rates?

Sid327 · Sep 21, 2019

Looking at the Prototype W4050
In post #22 above.....and going by memory, so I need help on this. Once W4050 was fitted with the 2-stage engines it became the fastest Mossie (no doubt verified correctly).
If so and just musing here. I assume it did so with the type of (earlier) props shown in the picture(?)
What if it were fitted with the paddle-blade props that the later aircraft had, or even the 4-blade props fitted to some.
Would that have made any difference?

As an aside I remember TT35's flying around Heybrook Bay (Naval gunnery range on the coast near Plymouth) in the distant past and will never forget that sound.

Navalwarrior · Sep 26, 2019

glennasher said:
Weight is not your friend, four .50s weigh a considerable sum, add the ammo and the situation gets even worse. Not to mention the COG shift to the rear. The Mossie was pretty fast and hard to keep up with, as it was.
All in all, the penalties in weight would outweigh any minor benefit.

Resp:
If one waits to let an attacker get on ones tail, then the attacker also has time to fire on the Mosquito.

Thos9 · Oct 2, 2019

A lighter wing on the A-6 - interesting. Care to share some good data/sources on it?
Kay and Smith "German Aircraft of the Second World War" (2002) p99: the Fw 190A-6 "had a a redesigned wing which was lighter and could take four 20 mm MG 151/20 cannon."
I agree that for the 190 Jabo the 801 radial was optimal, but for air superiority and interception a 603 or 213 V12 was better: lower drag, more power at altitude and potentially a better sight angle. Wing radiators would fit behind the landing gear legs as in the Spiteful (for example).

Denniss · Oct 4, 2019

The only redesign in the wing should have been structural changes to support the outer wing MG151E and its ammo belts instead of MG FF and its ammo drum. Don't know if they left some additional space free for the MK 108 or if the wing was later changed again to support this cannon as well.

stona · Oct 4, 2019

pirate_smee said:
The British air ministry forced De Havilland to install a turret in a mock up, but the speed reduction was significant, so it was drooped.
Some pictures of the mosquito turret installation.
De Havilland Mosquito

The first Mosquito to fly with a mock up four gun turret was prototype W4050, on 24th July 1941, the turret cost, on average 20 mph and was thankfully never adopted. Nuuumann has covered this in his answer.

The turret lived on in the turret fighter. The turret fighter concept was not abandoned in 1940/41 and gained some traction with the Mosquito. It was proposed, for example, as a long range convoy escort.

In mid April 1941 de Havilland were told to finish two fighters with four machine gun Bristol turrets. W4053 and W4073 were selected.

W4053 was flown out of Salisbury Hall Field on 14th September, shedding part of its turret on the way to Hatfield.

W4073 was flown out of the same field on 5th December with a mock up turret. This was soon removed and faired over at Boscombe Down. W4073 had dual control and would eventually be used as a trainer.

The turret did impose a speed penalty of between 12 mph and 20 mph, depending on the position of the guns and fairing used. This was not the reason the turret was abandoned. This was due to the success of the fixed cannon armament in the fighter version (cannon were first fired from W4052 on the Hatfield butts on 5th May) which rendered the turret fighter redundant.

Mosquito rear guns

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