Westland Whirlwind revisited

[Wild_Bill_Kelso]

But it seems they solved that problem (going from small peregrine to larger merlin) with the Welkin, so maybe they did the hard part already.

 

[Shortround6]

OK guys repeat after me.

Whirlwind has 250 sq ft wing.
Whirlwind has 250 sq ft wing.
Whirlwind has 250 sq ft wing.
Hurricane has 258 sq ft wing.
Whirlwind has 250 sq ft wing.
Whirlwind has 250 sq ft wing.
Whirlwind has 250 sq ft wing.
Spitfire has 242 sq ft wing.
Whirlwind has 250 sq ft wing.
Whirlwind has 250 sq ft wing.
Whirlwind has 250 sq ft wing.
Sea Hornet has 361 sq ft wing.
Whirlwind has 250 sq ft wing.
Whirlwind has 250 sq ft wing.
Whirlwind has 250 sq ft wing.

When idea of twin Merlin Whirlwind enters your head, lay down in a quite place and repeat the above until the feeling passes.

BTW the Sea Hornet had the same wingspan as the Whirlwind.

 

[pbehn]

OK guys repeat after me.

Whirlwind has 250 sq ft wing.
Whirlwind has 250 sq ft wing.
Whirlwind has 250 sq ft wing.
Hurricane has 258 sq ft wing.
Whirlwind has 250 sq ft wing.
Whirlwind has 250 sq ft wing.
Whirlwind has 250 sq ft wing.
Spitfire has 242 sq ft wing.
Whirlwind has 250 sq ft wing.
Whirlwind has 250 sq ft wing.
Whirlwind has 250 sq ft wing.
Sea Hornet has 361 sq ft wing.
Whirlwind has 250 sq ft wing.
Whirlwind has 250 sq ft wing.
Whirlwind has 250 sq ft wing.

When idea of twin Merlin Whirlwind enters your head, lay down in a quite place and repeat the above until the feeling passes.

BTW the Sea Hornet had the same wingspan as the Whirlwind.

The Typhoon had the same number of cylinders as a Whirlwind, with slightly less swept volume and slightly more wing area.

 

[Shortround6]

Even a pair of Merlin IIIs are almost 400lbs more than Sabre, I doubt the props are going to be 1/2 the weight, and the cooling systems are not 1/2 the weight of the Sabre cooling (including oil) and so on.
The Whirlwind with Peregrines is a good match for the Typhoon, Trying to stick in Merlins calls for a lot of imagination. I know there is a letter but the part/s I have seen (not more than what somebody put in a book) simply say they can do it without saying how and they were fighting the cancelation of hundreds of aircraft when they said it.

And it is not just the weight, it is the volume of where the stuff is supposed to go, Add and extra bay (rib) between the engines and fuselage for more cooling space? You are going to need more than 134 Gal of fuel. Whirlwind was already running smaller, higher pressure tires than most other RAF planes. All the other planes did gain weight but the Whirlwind was just about at the top end of the scale in 1940. May have been heavier than early Typhoons with twelve .303 guns?

 

[MiTasol]

Adding a bay between the fuselage and the engines would probably be the most feasible way to fit Merlins - it provides the extra space for additional cooling and additional fuel.

Downsides as Shortround said are the tyres are already at their limit so enlarging the wheels, tyres and brakes is going to need space and add weight.

Additional downsides are the reduction in roll rate from the longer wing and increased engine mass plus possibly higher wing loading.

 

[don4331]

You're adding 2 bays to your Merlin Whirlwind in you're adding fuel as the Whirlwind has its fuel outboard of engines. The bay inside the fuselage and engines is required for the extra foot (0.3m) of propeller radius for Merlins. The extra propeller diameter also means you need taller landing gear so the prop isn't mowing the grass on take off. So, then you need to do something similar to Fw.190D and move the tail back to maintain the correct landing altitude. Merlin IIIs would adding 100+ kg/engine alone, probably double that with all ancillaries.

In contrast inline Ha40 to the radial Ha112 is only 54kg difference including all ancillaries. Jumo 213 is within 30kg of BMW801, noting that even after ancillaries, the Fw190D is lighter than its radial engined counterpart was.

Famous Aircraft of the world has empty weight of Typhoon 1A at 3,460 kg, so Whirlwind I at 3,770 is 300+ kg ~10% heavier with 10% wing area - 279 for Typhoon versus 250 for Whirlwind.

S Shortround6 You can add P-38 Lightning at 327 sq ft

Petters designed the Whirlwind ro get maximum performance out of a Kestrel sized powerplant; he didn't (couldn't) design an airplane big enough to support Merlins later while being competitive on Peregrines.

 

[MiTasol]

You are right about the need for longer legs and a longer fuselage to keep the cg within limits. It all adds up to too many changes to keep the same name. Manchester to Lancaster to Lincoln was far simpler.

 

[ThomasP]

You could fit a 4-blade propeller with wood blades (ie Rotol) to keep the diameter the same and absorb the power (and therefore not have to increase the landing gear length) and keep weight increase to a minimum.

 

[MiTasol]

Those Rotol props were VERY heavy. I can pick up a four blade Ham Std or Curtiss Electric hub assy less blades but no way can I pick up a Rotol hub.

 

[tomo pauk]

In contrast inline Ha40 to the radial Ha112 is only 54kg difference including all ancillaries. Jumo 213 is within 30kg of BMW801, noting that even after ancillaries, the Fw190D is lighter than its radial engined counterpart was.

Fw 190D9 was at 4300 kg full, clean - same as the Fw 190A8 that was armed with an extra pair of MG 151s (and the ammo). Extra weight of powerpant of the 190D was due to the presence of the liquid cooling system.

Due to the powerplant tye used (= relatively lightweight radial, no liquid cooling system), the Ki-100 ended up lighter than the late Ki-61s.

 

[Capt. Vick]

A simple solution guys. Just add a couple of high power, low weight turbo props. Done and done. Now I will work on the tail issue. Geez. So simple.

 

[Wild_Bill_Kelso]

Are we maybe overcomplicating things a bit more than we need to?

Doesn't Welkin already have larger wheels? A modified tail? A modified (and more forward) cockpit? A slightly stretched fuselage and inner-wing section?

What if you just shortened the wings a bit

 

[Wild_Bill_Kelso]

Admittedly I should not be the designer, as mine looks a bit like one of those surreal Blohm und Voss UFOs, but you get the idea...

 

[GrauGeist]

If anything, those models show just how much larger the Merlin's nacelles were compared to the Perigrine's.

 

[Wild_Bill_Kelso]

If anything, those models show just how much larger the Merlin's nacelles were compared to the Perigrine's.

So do the nacelles on those R-2600's on an A-20, but they flew those around

A Welkin had a 70' span, a Whirlwind 45', an A-20 60'... that's fairly close to midway between the two

And yeah ok maybe deepen the wings a bit on the Whirlkin....

 

[ThomasP]

"Whirlkin" - good one, I like it.

 

[GrauGeist]

The nacelles on the Welkin show that they had to provide larger housings for the Merlin, which was a bit wider and almost a foot longer.
Add to that, about 500 pounds for each engine (dry).

 

[buffnut453]

So do the nacelles on those R-2600's on an A-20, but they flew those around

View attachment 710202

A Welkin had a 70' span, a Whirlwind 45', an A-20 60'... that's fairly close to midway between the two

And yeah ok maybe deepen the wings a bit on the Whirlkin....

Not sure what your point is. The relative size of engines on other airframes is entirely irrelevant. The problem with the Whirlwind, as others have pointed out, is that it was physically too small to accommodate the Merlin.

An inline engine requires bearers that run either side of the engine itself. That drives a main structural bulkhead that's wider than the engine. In the Whirlwind, that bulkhead was narrower than the Merlin which would require some really strange geometry for the engine bearers to make them wide enough which, in turn, means they likely lack the structural strength to hold the engine.

Show me one example of an inline engine mount where the main bulkhead is narrower than the engine itself. I've never seen one.

Bottom line is that the Whirlwind's manufacturer decided it was impossible to integrate the Merlin into the airframe. Had it been achievable, it would have been done.

 

[ThomasP]

According to Westland the Merlin XX could be integrated with the airframe, and the Merlin-Whirlwind could have been in production by the end of 1941. But the decision by the Air Ministry was made to end production based on the rationalization of the Merlin-Whirlwind using 2 engines vs 1 - as well as 50% more material otherwise - in comparison to the Spitfire.

See this post: "A 12-gun fighter with 2 RR Kestrel engines for the RAF?"

 

[MiTasol]

Not sure what your point is. The relative size of engines on other airframes is entirely irrelevant. The problem with the Whirlwind, as others have pointed out, is that it was physically too small to accommodate the Merlin.

An inline engine requires bearers that run either side of the engine itself. That drives a main structural bulkhead that's wider than the engine. In the Whirlwind, that bulkhead was narrower than the Merlin which would require some really strange geometry for the engine bearers to make them wide enough which, in turn, means they likely lack the structural strength to hold the engine.

Show me one example of an inline engine mount where the main bulkhead is narrower than the engine itself. I've never seen one.

Bottom line is that the Whirlwind's manufacturer decided it was impossible to integrate the Merlin into the airframe. Had it been achievable, it would have been done.

The Allison mount is a lot narrower than theenine