Bistol Type 153 wins the F.37/35, no W. Whirlwind

[don4331]

And there was also the F director or Type F sight that was included in the equipment of aircraft like the Barracuda. This was developed by the RAF from 1937. The pilot pointed the aircraft at the target ship, fed in range and speed data etc, and the sight / director set the deflection needed on the torpedo. This superseded the crude arrangement of a sighting bar in front of the cockpit of aircraft like the Swordfish and Albacore, with the pilot doing all the maths involved.

E EwenS : Do you have any additional information on the F director? (I checked most of the Tech pages on the site here, and didn't find anything but might have missed when distracted by other interesting things of note...)

The old system:
Flying my airplane, to arrive at a point 400m* abeam (assuming 40kn torpedo) and 10x the speed of ship in front (e.g. 300m for the 30kn Bismarck), basically keeps me out of LAA range until last possible moment (3/4/5 triangle, says I am 500m away at torpedo drop - decently long range for iron sights at Swordfish doing 100mph and in theory only 1/4 of the LAA can be brought to bear as the rest needs to watch the other 3 quarters). MAA with director control is problem, but hopefully I am between shots of the semi-auto cannons (and again same 1/4 limit).

What you are describing:
Flying directly at the ship - 0* deflection scare the $#!+ out of me as a pilot: 1/2 the LAA and MAA would be targeting me and while there is a slight convergence issue as all the guns aren't exactly midships, I'm not getting warm fuzzies that I'm not a big target.
Even as an engineer, getting the gyros on the plane to provide accurate enough data on speed and range to program the torpedo's gyro for the required deflection seems at technological limits for '37. And then the torpedo has to execute both the stabilization for depth and the turn to the require angle in the 400m (maybe a little more with the curve). It does help that it is a 1D problem of 100+ meters; don't need to worry about it moving up/down, and torpedo is running through anything ahead of it.
So, any data you have is appreciated.

*400m being more/less the distance for torpedo to have achieved stable running depth/armed, which allows minimum time for evasive maneuvers of the vessel.

 

[EwenS]

D don4331
I must admit I don't recall reading about it before but must have since I have references in a couple of books in my library. Anyway, here is what I have.

From "British Military Airfield Architecture from Airships to the Jet Age" by Paul Francis published in 1996, under the section on the Torpedo Attack Trainer:-

"The Torpedo Attack Trainer (TAT) was a sophisticated device that provided instruction in the use of the F director system of torpedo attack on various types of ship within a simulated 'attack' environment."

After discussing the method used on the Swordfish and the need for estimates of speed range etc and calculation of the deflection required it goes on:-

"The F director, a computer in the aircraft, was fed with information by the pilot. The director in turn fed settings to the torpedo, calculating the amount of deflection required. The aircraft was positioned straight at the target ship, thus eliminating sighting error and the torpedo headed off at an angle after entering the water."

It then goes on to discuss the dive attack profile used by the Barracuda. At the bottom of the dive it continues

"At this point, dive brakes were raised and the aircraft flew level, and the settings on the F director controls adjusted as necessary; the target ship's speed was set to the known performance of the vessel, and the bow angle was corrected. When the ship started to turn, as a ship under attack always did, the 'avoiding action' was entered. The aircraft had to be straight and level with no roll or pitch since any error would affect the aim of the torpedo.

At this point, one aircraft would have the target head on and the other two would have a shot on the bow [my note - an attack by a flight of 3 was being described]. All three would drop their torpedoes, though no hit was expected from the head-on shot. If the pilots had got everything right, the other two would hit; the F Director was that good. Getting everything right was difficult which was why so much training was needed."

Then from "Naval Anti-Aircraft Guns & Gunnery" by Norman Friedman chapter 1 p22-27 under torpedo bombing (you might find this on internet in Google books depending on the browser you use).

"Torpedo attack was inherently dangerous because because the pilot had to point his aircraft more or less directly at the target, using a torpedo director like that on board a ship to solve the triangle of ship course and speed and torpedo course and speed. In 1934 the Germans demanded that future aerial torpedoes be capable of angling; they may have been the first to do so. In 1937 an RAF officerhad the same idea, and during the war British aerial torpedoes could angle, the attacker using a Type F sight. The Italians seem to have had the same idea. During the war the British initially rejected the US Mk 13 torpedo partly because it lacked this feature."

And Note 16 on page 317.

"The British torpedo school (and torpedo experimental establishment) HMS Vernon commented in 1934 that a torpedo dropped at high speed and considerable altitude would be difficult to aim because the torpedo's speed through the air would be so different from that through the water. A pilot dropping such a torpedo would find it difficult to take into account the time of flight of the torpedo before it entered the water. However, if the torpedo course were set once it was in the water, torpedo control would be greatly simplified. This argument seems not to have been accepted by the Royal Navy, which initially did not buy angled air torpedoes (the RAF seems to have adopted angling as an aid to survival). In 1937 the two services agreed to buy a single type of torpedo (Mk XII), which could be angled as the RAF wished. For the British officer who proposed angling for the RAF, see AIR 20/1132, the Minutes (1937-9) of the Aircraft Torpedo Control Sub-Committee (formerly Torpedo Sights Sub-Committee)."

Edit: additional info as site was not allowing me to continue with original post.

In 1937 the RN had the biplane Swordfish in service, the Albacore under design and the Barracuda at the beginning of the design process and not scheduled for service entry in 1940/41. The RAF had the biplane Vildebeest in service and had the Beaufort under design for service entry around 1939. So the problem identified in 1933 was obviously beginning to be taken seriously.

There is this training film about the Mk.XII torpedo but it makes no mention of angling.


In the first book I referred to there is a diagram of the TAT which includes a box marked "computer Type F" down around the pilot's feet. But the photos I posted have the bar arrangement as used on the Swordfish and Albacore which are missing from the diagram.

"The Fairey Barracuda" by Matthew Willis p42 includes this comment:-

"The Barracuda had introduced new technology in the form of a torpedo sight that enabled the pilot to set the direction of the projectile once it entered the water, and could be adjusted to compensate for evasive manoeuvres by the target vessel. Commander B.W. Vigrass described the method employed using the Barracuda and its 'F'-type torpedo Director:"

He then describes the dive attack method then goes on to note the dropping distance as 1,000 yards at 200 feet. This is in early 1943 when the Barracuda was newly in service.

"In a Swordfish aircraft it was necessary to aim the aircraft in the direction we wished the torpedo to travel and the torpedo sight consisted of a row of twelve flash light bulbs which enabled the pilot to calculate the lay-off angle appropriate to his estimate of the of the target's speed. In a Barracuda the pilot aimed the aircraft directly at the target and a control in the cockpit enabled him to apply the required lay-off angle to the torpedo. The torpedo entered the water in the direction the aircraft was travelling but it then changed course to the direction which had been pre-set by the pilot."

The book has an annotated photo of the left side of the Barracuda cockpit. There is a ledge just under the small window in line with the wing leading edge and outboard of the throttle controls and elevator trim tab controls. Forward of the cockpit light switches, is a control marked "control for inputting estimated ship speed and direction during torpedo attack, part of the Type F Torpedo Director".

In "Barracuda from the Cockpit" this control is described by a Barracuda pilot as follows:-

"Fitted on a shelf above the trim controls was an unusual instrument, namely the Torpedo Control. This was a metal disc about four inches in diameter with a circle printed on it which was divided into 360 degrees, with 0 degrees aft and 180 forward; '0 degrees' represented the heading of the target ship on a steady course. Mounted in the centre of the circle was a large switch shaped like a ship with a sharp end and a blunt end. This switch could be turned through 360 degrees and was connected directly to the controls within the torpedo. We could set the estimated ship's speed on the control, and there was another switch that could be moved from side to side and marked 'Avoiding', 'Away' or 'Towards'.

In terms of dropping speeds and altitudes "The Strike Wings" has a comment that the Mk.XV torpedo introduced about 1943 was capable of being dropped from 1,000ft at up to 350mph, but Beaufighters generally dropped from 175ft at 210mph.

The US Mk.13 was constantly improved during WW2. By June 1944 Avengers were cleared to drop them at 240knots +/- 10knots, at altitudes of 650ft +/- 300ft.

When the Avenger entered service with the FAA in 1943, I'm not sure which came first, the dissatisfaction with the Mk.13 or the need to use it as an ASW aircraft. It's use from the fleet carriers only became necessary in Oct 1944 when the Barracuda was struggling to cope with climatic conditions in the Indian Ocean. As the Avenger couldn't carry British torpedoes, the Mk.13 had to be adopted but it was never used.

In May 1945 the Admiralty issued instructions to the Barracuda squadrons in 11ACS (on the light fleet carriers en route to the Pacific) to stop practising torpedo strikes and concentrate on dive bombing.

Now the question is whether this device was ever fitted to any of the RAF torpedo bomber types? If so from when? The video would suggest not the Beaufort. The aircraft markings indicate it was shot pre-May 1942. Probably not the Wellingtons as they were theatre conversions in the Med. The most likely candidate would be the Torbeau Mk.X. I'll have to look out some cockpit photos.

Edit 2. To pick up on the Barracuda attack profile. Flights were generally of 6 aircraft flying as 3 pairs line astern, 500 yards between each pair. Approach at medium altitude. When c1 mile ahead of target turn across its bow and dive to low level. Dive lasted maybe 15 secs. Object was to have a pair on each bow of enemy ship and a pair ahead. Then turn towards enemy and drop torpedoes at 1,000 yards. Then turn away to get clear.

The approach from the bow minimises opportunities for gunners. And whichever way enemy turns he has at least a pair of TB on his flank.

These tactics were practised during training and on operational squadrons. Training would work up to multiple flights - one pilot mentions 36 aircraft (6 flights) being the ultimate. That would represent something like the TB complement of 2 Armoured carriers mid-war.

Unfortunately the Barracuda crews rarely got to use their torpedo tactics. There are only 1 or 2 recorded torpedo attacks against merchant shipping in late 1944 IIRC. Most of their work was with bombs in 1944/45.

 

[Howard Gibson]

Pretty conventional Type 153 was to be powered by a Bristol Hercules, armed with 4 cannons (per spec), and was among the 1st designes supposed to have the bubble canopy. Let's say Bristol's design wins instead of Westland's.
Will the RAF be better off, or not? Possible repercussions on future British, German and/or US fighter designs? The FAA version?

picture (not the best; the 153 is at the top right)

I find the use of the Bristol Hercules in a single engined fighter to be interesting. It was 38.7litres displacement, rather small for a successful radial engined WWII fighter. On the same fuel used by the Merlin_61s, it ought to be able to do 2000HP. Maybe Spitfire armament of two 20mm Hispanos plus some sorts of machine guns would have been a good compromise!

Did it really have a wingspan of of 46ft? That provides nice, low landing speeds on a carrier, and terrible performance in a dogfight.

 

[tomo pauk]

I find the use of the Bristol Hercules in a single engined fighter to be interesting. It was 38.7litres displacement, rather small for a successful radial engined WWII fighter. On the same fuel used by the Merlin_61s, it ought to be able to do 2000HP. Maybe Spitfire armament of two 20mm Hispanos plus some sorts of machine guns would have been a good compromise!

Zero have had 30L radial engine, and no access to high octane fuel, but it was still fairly successful. Hercules was making 1700+ HP before the 100 series and on 130 grade fuel, and 1900 HP from 100 series on - ballpark with BMW 801, R-2600 or ASh-82.
(more than 2100 HP for the post-war Mk. 762 and 763)

Spec asked for 4 cannon set-up, but wartime expediences often take precedence.

 

[EwenS]

The original Blackburn proposal in Jan 1940 for a fighter for the FAA used the Hercules. By April it was developed into the Sabre engined Firebrand proposal.

 

[Howard Gibson]

Zero have had 30L radial engine, and no access to high octane fuel, but it was still fairly successful. Hercules was making 1700+ HP before the 100 series and on 130 grade fuel, and 1900 HP from 100 series on - ballpark with BMW 801, R-2600 or ASh-82.
(more than 2100 HP for the post-war Mk. 762 and 763)

The Nakajima Sakae was 28litres. By mid-war, the Zero was increasingly out of it, mostly due to its small engine. I find the Zero's armour and protection discussion to be moot. Do you want to be only 30mph slower than the enemy, or do you want armour? On 2500HP, we can discuss how thick the armour should be.

Late in the war, the Germans were phasing out the BMW 801 out as a fighter engine. The R-2600 never reached service as a fighter engine. The ASh-82 was installed in La-7s late in the war, where they got good performance below 20,000ft. The Hercules was the smallest of these four engines.

Spec asked for 4 cannon set-up, but wartime expediences often take precedence.

Spitfires with the C-wings were capable of carrying four 20mm Hispano MkII cannons. They rarely did because they restricted the Spitfire's performance.

 

[tomo pauk]

The Nakajima Sakae was 28litres. By mid-war, the Zero was increasingly out of it, mostly due to its small engine. I find the Zero's armour and protection discussion to be moot. Do you want to be only 30mph slower than the enemy, or do you want armour? On 2500HP, we can discuss how thick the armour should be.

Late in the war, the Germans were phasing out the BMW 801 out as a fighter engine. The R-2600 never reached service as a fighter engine. The ASh-82 was installed in La-7s late in the war, where they got good performance below 20,000ft. The Hercules was the smallest of these four engines.

2500 HP for 1940-41 with one engine?
I didn't said that Zero was the ideal fighter, just pointed out that one can make a good fighter around an engine that is not of very big displacement. Note that engine power (via the thrust-producing propeller) propels the aircraft, displacement does not.

An 1430 HP engine in 1940 is more than enough to make a fighter around it, with firepower, protection and performance. So it is a 1670 HP engine in 1941.

Spitfires with the C-wings were capable of carrying four 20mm Hispano MkII cannons. They rarely did because they restricted the Spitfire's performance.

??
Thread is about Type 153, not about Spitfire.

 

[Howard Gibson]

??
Thread is about Type 153, not about Spitfire.

The Bristol 153 is all about Hercules engines and four 20mm cannons. I am trying to put all of this into some sort of perspective. How early in the war would this be available with 20mm cannons, and how late in the war would it be an effective fighter? Are there any alternative single engined fighters the RAF could have used instead?

 

[tomo pauk]

The Bristol 153 is all about Hercules engines and four 20mm cannons. I am trying to put all of this into some sort of perspective. (1) How early in the war would this be available with 20mm cannons, (2) and how late in the war would it be an effective fighter? (3) Are there any alternative single engined fighters the RAF could have used instead?

(my bold)
1 - Probably same as it was the case with Whirlwind or some cannon-outfitted early Spitfires, ie. by second half of the BoB.
2 - Until August 1945.
3 - OT, but yes.

 

[Shortround6]

I find the use of the Bristol Hercules in a single engined fighter to be interesting. It was 38.7litres displacement, rather small for a successful radial engined WWII fighter. On the same fuel used by the Merlin_61s, it ought to be able to do 2000HP. Maybe Spitfire armament of two 20mm Hispanos plus some sorts of machine guns would have been a good compromise!

Did it really have a wingspan of of 46ft? That provides nice, low landing speeds on a carrier, and terrible performance in a dogfight.

You can't swap the engine limits between the Merlin and Hercules like that.
The Hercules had some cooling limits/problems which were being worked on during the development/production of the engine. More cooling fins, different arrangements of fins and later in life copper alloy heads were used to get cooling up to where it needed to be for the higher power powers. Not to mention that sleeve valves didn't tolerate really high cylinder pressures all that well.
Hercules XVII was tested in a Beaufighter XX in Jan -March of 1943 at 10lbs boost.
The 100 series engines had a number of major changes.

The specifications for the Bristol 153 call for a 37ft wing span and 204 sq ft of wing area. Once you load it up with self sealing tanks, armor and other "stuff" (like a dinghy) the nice slow landing speed has disappeared.

Late in the war, the Germans were phasing out the BMW 801 out as a fighter engine. The R-2600 never reached service as a fighter engine. The ASh-82 was installed in La-7s late in the war, where they got good performance below 20,000ft. The Hercules was the smallest of these four engines.

The AHh-82 got good performance because they put it in a small airplane. 189 sq ft of wing and gross weight of 7300lbs and they restricted the armament to two 20mm ShVAK caoon or three 20mm Berezin cannon to get that performance.

What level of Hercules performance are you expecting to get in the initial stages?

 

[tomo pauk]

The AHh-82 got good performance because they put it in a small airplane.

That would be "The La-7 got good performance because it was a small airplane"?

 

[Shortround6]

The Bristol 153 is all about Hercules engines and four 20mm cannons. I am trying to put all of this into some sort of perspective. How early in the war would this be available with 20mm cannons, and how late in the war would it be an effective fighter? Are there any alternative single engined fighters the RAF could have used instead?

Early would have been about the BoB judging from the availability of the cannon.
Which didn't work well when tilted on their sides. The Bristol wasn't tilted as bad as the Spitfire wing but it wasn't vertical either.

It would have been a day late and dollar short for it's entire career using the Hercules engine. Which only became available in numbers (more than a 3-400?) in 1941

The Merlin III was good for around 1300hp when running at 12lbs of boost in 1940. The Merlin XII was a bit better and The Merlin 45 (in the spring of 1941) blows it out of the cricket pitch.

The Hercules VI engine was uprated from 7lbs of boost to 8lbs of boost in May (?) of 1942.

Chances of the Bristol 153 ever making it's promised speed is about zero.
The Bristol 156 fighter (Beaufighter) was originally estimated at 370mph.

 

[Shortround6]

That would be "The La-7 got good performance because it was a small airplane"?

same difference

or

"The ASh-82 got good performance in the La-7 because it was a small airplane"

 

[tomo pauk]

The Merlin III was good for around 1300hp when running at 12lbs of boost in 1940. The Merlin XII was a bit better and The Merlin 45 (in the spring of 1941) blows it out of the cricket pitch.

The Hercules VI engine was uprated from 7lbs of boost to 8lbs of boost in May (?) of 1942.

Hercules VI was making 1670 HP in 1941.

Chances of the Bristol 153 ever making it's promised speed is about zero.

How do you figure?

same difference

or

"The ASh-82 got good performance in the La-7 because it was a small airplane"

The Type 153 was also a small airplane.

 

[tomo pauk]

The Bristol 156 fighter (Beaufighter) was originally estimated at 370mph.

We can take a look at Beaufighter.
Wing was 19% thick at root + wing area of 503 sq ft = draggy item of a big size. Two radial engines sticking out. Fuselage of such a big cross section where the aft gunner can go from it's seat and change ammo drums.
If all of that does not say "I'm as draggy as a house", nothing will.

 

[Jabberwocky]

Hercules VI was making 1670 HP in 1941.

On a bench, or in service?

I can't find any reference to any Hercules VI powered aircraft entering service until June/July 1942, with the Beaufighter Mk VIF.

 

[Admiral Beez]

That would be "The La-7 got good performance because it was a small airplane"?

The La-7 was small. Smaller than a Curtiss P-36 from nine years earlier but with 80% more hp.

I don't think many single engined fighter of 1944 were this tiny. It's two feet shorter and four feet narrower than a Ki-84, for example.

 

[Shortround6]

Hercules VI was making 1670 HP in 1941.

when and what altitude?
Making a useful fighter in late 1941 or early 1942 after making a poor fighter in 1939-40 doesn't seem like a good trade off.

How do you figure?

Go back to post #6

Compare to the Japanese Ki-44 II.
A smaller wing, a lot less gun weight, an engine that weighed about 100gk less and yet the Ki-44 II is only a few kg off from the claimed weight of the Type 153?

Bristol's cowl design department left something to be desired in 1938-42.

A great many British designs (but not all) in the late 30s suffered because the British didn't have the high speed design experience or the wind tunnel data to properly estimate drag in the mid to high 300mph range. Drag can make a sudden rise that speed range after following a fairly predictable path/curve from low speed to that point.

Not to pick on the British, a number of American companies came up with some truly amazing performance estimates. Like the Douglas XP-48 and the Tucker XP-57.
Or the Curtiss XP-46 which was supposed to go 403mph using the same engine as the P-40D/E. Actual tests with operational equipment (like guns) recorded 355mph.

 

[tomo pauk]

On a bench, or in service?

I can't find any reference to any Hercules VI powered aircraft entering service until June/July 1942, with the Beaufighter Mk VIF.

FWIW (although the rated altitude and speed is a bit on the optimistic side):

 

[tomo pauk]

when and what altitude?
Making a useful fighter in late 1941 or early 1942 after making a poor fighter in 1939-40 doesn't seem like a good trade off.

Whirlwind was even worse in 1939 and in 1st 8 months of 1940 - namely, it wasn't available.
See post #99 for June of 1941 for Hercules VI. 1670 HP was produced at low altitude, as one can expect: RAF data card says at 7500 ft, Bristol table says at 4500 (I'd believe that data point better).
For 1940, the Mk. III does 1400+ at low altitudes.

Compare to the Japanese Ki-44 II.
A smaller wing, a lot less gun weight, an engine that weighed about 100gk less and yet the Ki-44 II is only a few kg off from the claimed weight of the Type 153?

You were questioning the speed of the Type 153, not rate of climb.
With engines of same power, speed is about drag, rate of climb is about weight, and we don't know anything about the claimed RoC for the 153.

Bristol's cowl design department left something to be desired in 1938-42.

A great many British designs (but not all) in the late 30s suffered because the British didn't have the high speed design experience or the wind tunnel data to properly estimate drag in the mid to high 300mph range. Drag can make a sudden rise that speed range after following a fairly predictable path/curve from low speed to that point.

How bad were Bristol cowls in 1938-42 vs. anyone else (bar BMW with 139 and 801)?
Sudden rise of drag was a problem with thick wings (is that a thing for the Type 153?) and with very high speeds, talk 400-450 mph at 25000 ft (way, way above the manufacturers claims for Type 153, both for speed and altitude).

Not to pick on the British, a number of American companies came up with some truly amazing performance estimates. Like the Douglas XP-48 and the Tucker XP-57.
Or the Curtiss XP-46 which was supposed to go 403mph using the same engine as the P-40D/E. Actual tests with operational equipment (like guns) recorded 355mph.

Unlike Curtiss, Bristol was not promising the moon.