Supermarine Type 327

[wuzak]

The Type 327 was an updated version of the Type 324, which was proposed to the F.18/37 specification which led to the Typhoon.

The main difference between the Type 324 and Type 327 is that the former's 12 x 0.303" in the outer wing panels were replaced by 6 x 20mm cannon in the wing roots, as the 327 was proposed to as a cannon armed fighter.

The engine choices were the Merlin RM.2SM (Mk X??) and the Taurus TE-3SM.

The engine performances:

Merlin RM.2SM
Fuel: 100 octane

Supercharger Gear	High	Low
Maximum Power (bhp)	1,145	1,265
at Altitude (ft)	16,750	9,500
International Rating (bhp)	1,135	1,250
at Altitude (ft)	15,500	8,000
Power at Economical Cruising Speed @ 15,000ft (bhp)	-	233
Take-off Power (bhp)	-	1,300
RPM	-	3,000
Reduction Gear	0.42	0.42
Dry Weight (lb)	1,390	1,390

Taurus TE-3SM
Fuel: 100 octane

Supercharger Gear	High	Low
Maximum Power (bhp)	1,165	1,250
at Altitude (ft)	15,000	5,000
International Rating (bhp)	980	1,080
at Altitude (ft)	15,000	5,000
Power at Economical Cruising Speed @ 15,000ft (bhp)	-	226
Take-off Power (bhp)	-	1,200
RPM	-	3,300
Reduction Gear	0.444	0.444
Dry Weight (lb)	1,345	1,345

Estimated performance:

Engines	Merlin	Taurus
All Up Weight (lb)	11,312	10,536
Maximum Speed (mph)	465	430
at altitide (ft)	22,000	20,000
Speed at 15,000ft (mph)	423	404
Economical Cruising Speed (mph)	210	195
at altitide (ft)	15,000	15,000
Service Ceiling	40,000	35,500
Take-off Over 50ft, no wind (yd)	409	465
Landing Over 50ft, no wind (yd)	439	393

The wing had a span of 40ft and wing area of 304sq.ft. It was fitted with Fowler Flaps which covered 57.5% of the span.

The wing was structurally very similar to the Spitfire's. It was described has having a single spar at the maximum thickness. It was built in 5 sections:
The centre section was built with the fuselage and contained the 6 20mm cannon installation.

The mid sections contained the engine, the radiator (buried in the wing outboard of the engine, fed from a leading edge intake), the main landing gear (folding inwards), the Fowler flaps and mechanisms and fuel tanks in the leading edge inboard of the engine (68 UKG each, and forming part of the structure) and in the engine nacelle (42 UKG each).

The outer wing panels contained the ailerons. These could be swapped for panels conaining 6 0.303" mgs for the ground attack role.

The wing section was of the NACA 2200 family, as was the Spitfire's.

The basic dimensions were:

Engines	Merlin	Taurus
Span (ft)	40	40
Gross Area (sq.ft)	304	304
Length Overall (ft)	33.5	33.5
Height on Wheels (static) (ft)	9.75	9.75
Chassis Track (ft)	12.5	12.5
Wheelbase (ft)	9	9
Airscrew Diameter (ft)	10.3	8.75

The weight break down was:

Engines	Merlin	Taurus
Structure (lb)	3,776	3,696
Power Plant (lb)	4,410	3,809
Load	3,126	3,031
All Up Weight	11,312	10,536

The breakdown of the load was:

Engines	Merlin	Taurus
Pilot and Parachute	200	200
Fixed Military Load	583	583
Removeable Load	875	875
Fuel (at 7.2lb/UKG)	1,225	1,265
Oil	243	108
Load	3,126	3,031

 

[wuzak]

The Type 324 had been rejected in favour of the Typhoon/Tornado because the Air Ministry saw no advantage over a single engine type.

A new requirement for a cannon engined aircraft came up, so Supermarine submitted its revised design.

Some members of the Air Ministry were keen, as the only cannon armed fighter on the horizon was the Whirlwind, with the possibility of the Beaufighter and Gloster F9.37. Others weren't so keen, citing Supermarine's inability to rapidly build prototypes and bring them into production.

Some features of the Type 327 were also criticised as unwaorkable - such as the cannon armament. At the time of the proposal the Hispano was fed with a drum. The Type 327 arrangement had the drums mounted in the fuselage, the rounds being fed to the guns via flexible feed chutes. This was thought impractical by some.

One disadvantage the Type 327 had against the proposed Beaufighter was that it only had one crew member, whereas the latter had a second, who could change ammo drums in flight.

Interestingly the Type 327 didn't have ejection chutes for the spent casings, but a collection box. Supermarines suggested that these could be reused.

 

[tomo pauk]

Thanks for the detailed overview.

Some of the details can raise an eyebrow, however. The specified Taurus engine, featuring a two-speed supercharger, and offering more than 1100/1200 HP was never a real production engine, at least going by Lumsden. The specified Merlin offers more power than Merlin X at FT heights, but at a lower altitude than Merlin XX?
The wing profile might belong to the NACA 2200 series, but it is not as thin as Spitfire's (circa 13%), at least when one looks at pics drawings available on the 'net. Supermarine was hoping for 430 mph on 1165 HP radials, the similarly sized Ki-45 was good for some 336 mph. The P-38L was not able to beat 430 mph mark, even with 2 x 1600 HP aboard (and admitedly no exhaust thrust).

 

[wuzak]

Thanks for the detailed overview.

Some of the details can raise an eyebrow, however. The specified Taurus engine, featuring a two-speed supercharger, and offering more than 1100/1200 HP was never a real production engine, at least going by Lumsden. The specified Merlin offers more power than Merlin X at FT heights, but at a lower altitude than Merlin XX?
The wing profile might belong to the NACA 2200 series, but it is not as thin as Spitfire's (circa 13%), at least when one looks at pics drawings available on the 'net. Supermarine was hoping for 430 mph on 1165 HP radials, the similarly sized Ki-45 was good for some 336 mph. The P-38L was not able to beat 430 mph mark, even with 2 x 1600 HP aboard (and admitedly no exhaust thrust).

Yes, it does appear that the wing is thicker. My rough calcs show a thickness of 19% at the root.

 

[GregP]

In case you haven't seen it ...

 

[wuzak]

Thanks Greg.

That shows an interesting point of the Type 327 - the exhaust was taken via a manifold and dumped out the back end of the nacelle, an attempt to gain exhaust thrust.

 

[Shortround6]

Trouble is that may not work as well as short stubby exhaust nozzles. It may have lower drag though.

Since exhaust thrust is dependent on the mass of the exhaust flow times the velocity of the exhaust gases at the exit/nozzle, long ducts that slow the exhaust gasses and/or allow them to cool (reducing pressure/velocity) aren't going to give the thrust of short/stubby pipes.

 

[wuzak]

True SR, but they may have not realised that at the time. There was a bit of development of exhaust stubs for the Merlin during the war, for both maximising thrust and reducing glare.

 

[GregP]

Both of your above comments assume the model builder was correct and, in that context, are good points.

I have seen several different illustration of the 327, and several don't agree with one another. I suppose that is natural seeing as how it was a paper aircraft and never flew. Changes are to be expected, I suppose. If anyone has a better illustration, post it by all means.

 

[wuzak]

I believe that model you posted was made by Supermarine.

Anyway, a couple of drawings from the proposal.

Wing layout

Close up of nacelle elevation

Armament layout

 

[wuzak]

Pictures of the mockup

 

[GregP]

Pretty darned cool, Wayne! Thanks!

I think it would have been a bit better with two wings and three wheels, though ... asymmetric as hell! And ... no propellers to boot.

What were they thinking? Too much beer, no doubt. Maybe Spitfire Ale?

 

[wuzak]

Pretty darned cool, Wayne! Thanks!

I think it would have been a bit better with two wings and three wheels, though ... asymmetric as hell! And ... no propellers to boot.

What were they thinking? Too much beer, no doubt. Maybe Spitfire Ale?

Probably couldn't be bothered doing the other half because they weren't getting paid for it!

 

[GregP]

No doubt about it. Maybe they ran out of sandpaper and decided to call it a a day!

I like the rear ejector exhaust, but wonder about the field maintenance. Closed-in hot things tend to burn things around them and be difficult to work around. Perhaps it was different than it appears on the surface. If the manifolds were routed out of the way, maybe they weren't such a hit on servicing the aircraft.

 

[Jabberwocky]

Beautiful looking aircraft. Supermarine really had an eye for flowing curves.

The speed projects seem a bit … ambitious. Although that wasn't uncommon with paper aircraft of the time. There were umpteen 450 mph + aircraft of the early 1940s that never made it off the ground.

With only 1265-1300 hp, I suspect that the Type 327 may have made something more like 420 mph, maybe 430 mph.

Wing area is about 93% of that of the P-38. Even if the Type 327's single-fuselage offers a drag advantage over the P-38's twin-boom design, I don't see the aircraft making 60+ mph more than a P-38G with less power and at lower altitudes,

Look at the Westland Whirlwind. Although a little handicapped by the Peregrines, it was smaller, lighter and had less frontal and wing area than the proposed Type 327 and made 360 mph on 885 hp. When Petter proposed re-engineering it to take Merlin XXs, which were producing 1125 hp at the time, the on-paper proposal speeds were 410-422 mph.

 

[tomo pauk]

Enjoy some bacon, wuzak
Any chances there would be more schematics, or hi-res of those posted above?

 

[parsifal]

looks very interesting. i never knew about this a/c. looks like a possible contender for the mossie in some respects

 

[Balljoint]

Look at the Westland Whirlwind. Although a little handicapped by the Peregrines, it was smaller, lighter and had less frontal and wing area than the proposed Type 327 and made 360 mph on 885 hp. When Petter proposed re-engineering it to take Merlin XXs, which were producing 1125 hp at the time, the on-paper proposal speeds were 410-422 mph.

It's a shame that the Whirlwinds were parked up north during the BoB. An actual record of what this type of aircraft could do –or not- would be useful. Still, if the WWs hadn't been operational, I can't see building them.

 

[wuzak]

Enjoy some bacon, wuzak
Any chances there would be more schematics, or hi-res of those posted above?

Thanks for the bacon!

I do have some more schematics.

 

[wuzak]

It's a shame that the Whirlwinds were parked up north during the BoB. An actual record of what this type of aircraft could do –or not- would be useful. Still, if the WWs hadn't been operational, I can't see building them.

According to Wiki the squadron with Whirlwinds wasn't operational in time for the BoB and the aircraft were being delivered slowly. At one stage they had 5 Whirlwinds, all of which were unserviceable.