Super Blenheim fighter

[tomo pauk]

I am just an old firefighter but with water putting kinks and turns in hoses/pipes can lead to a lot of pressure/flow losses.
I imagine that air is the same. The Allison P-40 and P-51s had a really nice intake, Long and smooth with one roughly 90 degree turn into the carb.
109 used one 90 degree bend, Early Spitfire used one 90 degree bend

Some of the "using an intake in the leading edge of the wing" may look nice but how many twists and turns does it make getting to the carb?
How many 90 degree bends in the Whirlwind intake? at least two? maybe more but shallower bends?
The supercharger multiplies the inlet pressure so just a small drop is a significant change near or above critical altitude.

Whirlwind exhaust was pretty terrible also from a thrust stand point. Might have been good for flame suppression?

Seems like there were at least two problems to iron out before we start blaming the propellers. And far easier to pinpoint.

An improved Whirlwind, and Spitfire Mk. III's. Now THERE is a What If scenario for 1940!

Very true.

It would still struggle to intercept the German Schnellbombers

German Schenellbombers - were there any?

 

[buffnut453]

I wonder what the Blenheim would do with a pair of Peregrines or early Merlins, both with chin rads.

Probably akin to the poor old Jet Provost…constant speed, variable noise.

 

[yulzari]

One might consider the difference is between an attacking fighter at maximum speed and a bomber in formation at cruising speed rather than comparing maximum speeds. If you can simply force the bombers to fly at their maximum speeds then you have reduced their effective range by inducing a much higher fuel consumption. A strategic 'kill' if not a tactical one with a smart line of little swastikas alongside the cockpit of the intrepid pilot.

You also impact the possible bomb load for the same reason and preventing external bomb carriage.

Many a failed attack causes the bombs to be dumped and the throttle opened wide for a run for home. A mission kill.

A bit like torpedos are cool but sea mines are uncool. Even if mining is often more effective, even when not going bang as they restrict movement.

A Schnell bomber can be its own worst enemy unless the speed is sufficient to protect it and it can make more effective precision attacks than the standard model bomber.

 

[tomo pauk]

A Schnell bomber can be its own worst enemy unless the speed is sufficient to protect it and it can make more effective precision attacks than the standard model bomber.

(my bold)
And again - the oxymoron

 

[don4331]

I am just an old firefighter but with water putting kinks and turns in hoses/pipes can lead to a lot of pressure/flow losses.
I imagine that air is the same. The Allison P-40 and P-51s had a really nice intake, Long and smooth with one roughly 90 degree turn into the carb.
109 used one 90 degree bend, Early Spitfire used one 90 degree bend

Some of the "using an intake in the leading edge of the wing" may look nice but how many twists and turns does it make getting to the carb?
How many 90 degree bends in the Whirlwind intake? at least two? maybe more but shallower bends?
The supercharger multiplies the inlet pressure so just a small drop is a significant change near or above critical altitude.

Whirlwind exhaust was pretty terrible also from a thrust stand point. Might have been good for flame suppression?

Someone should have told de Havilland that "using an intake in the leading edge of the wing" just looked nice and that the Hornet wouldn't be fast as a result. (Probably the same for Grumman with the F7F Tigercat, Vought F4U Corsair and a few others).

Whirlwind wasn't the only plane that engine power => air intake requirements changed dramatically between concept and squadron service.

Peters and co taking criticism constructively would have helped -> we're not calling your baby ugly - heels, pearls and a little rouge helps everyone.​

The Whirlwind needs 3 things:

1. Rolls-Royce to commit to at least 500 Peregrine I's in '38.* They can worry about reverse rotation II's after the 1st 500 have been used up.​

a. A sub function of this; Whirlwind needs to be prioritized over Lysander. RAF needs squadron(s) of heavy fighters for BoB.​

2. The flaps need to be disconnected from the cooling system - RAF can't afford to have pilots frying engines because they raised the flaps while taxying back to their hardstand.​

3. The hydraulic throttle needs to be binned until the leaks are cured. Having to regularly manipulate the throttles to maintain control of the engines is workload the pilot doesn't need. Again, having engines blow up because they were over-speeding and the pilot couldn't slow them down is something Westland doesn't need...​

Next:​

4. Tail redone - accelerating air both vertically (horizontal stabilizer) and horizontally (fin) concurrently was causing local compressibility. Hence, the 'acorn'. That's only going to get worse flying higher and/or faster.​

​

Improved intake/exhaust and propellers may be worked on after the airplane after squadrons have a reliable airplane, in quantity.

The last place that you want an airplane with 'teething issues' is 1/2 way around the world from the manufacturer.​

Additional ammunition capacity and fuel, uprated engines, etc. can wait.

*I can't help but thing getting Canada to build the Kestrel/Peregrine would have helped:

We wanted to build the Sabre as we thought the Merlin was too small. (Hey, it looked like a 1k hp engine in '38 and bomber were going to soon need 2k hp.)​

RR selling Canadian gov't that the Peregrine was stepping stone to the Vulture is the angle I'm proposing.​

 

[MiTasol]

I am just an old firefighter but with water putting kinks and turns in hoses/pipes can lead to a lot of pressure/flow losses.
I imagine that air is the same. The Allison P-40 and P-51s had a really nice intake, Long and smooth with one roughly 90 degree turn into the carb.
109 used one 90 degree bend, Early Spitfire used one 90 degree bend

Some of the "using an intake in the leading edge of the wing" may look nice but how many twists and turns does it make getting to the carb?
How many 90 degree bends in the Whirlwind intake? at least two? maybe more but shallower bends?
The supercharger multiplies the inlet pressure so just a small drop is a significant change near or above critical altitude.

Whirlwind exhaust was pretty terrible also from a thrust stand point. Might have been good for flame suppression?

In general yes but there are some "strange" caveats. The early DC-3/C-47 series with Pratts had a nice sweeping carb inlet travelling through about 100 degrees but later ones had the top corner a sharp angle and they were more efficient. Never did see an explanation for that but I would hazard a guess it is related to Bernoulli's law and converting velocity into pressure.

 

[Shortround6]

In general yes but there are some "strange" caveats. The early DC-3/C-47 series with Pratts had a nice sweeping carb inlet travelling through about 100 degrees but later ones had the top corner a sharp angle and they were more efficient. Never did see an explanation for that but I would hazard a guess it is related to Bernoulli's law and converting velocity into pressure.

The later C-47s (and a number of other radial engines) had sand filters installed at the rear of the inlet, the actual air inlet curved down a little earlier. The solid particles tended to go straighter and go through the curved slats at the sharp bend to the outside of the actual intake tract. There were different designs, sometimes the dirt trap was in front(?) like Martin Baltimores? Some P-38s had two inlets. The normal one on the outside of the cowl and an inner one with a filter that drew from the landing gear well. Obviously only used for take-off and landing but that is when dust/dirt was the worst.
Like a lot of other things they were learning a lot between 1936 and 1942-43 in regards to airflow and later installations that look similar from the outside may be a lot better than early installations. Larger passages and gentler bends can do a lot.

For the Whirlwind I can't find any photos of the air intake (inside the radiator bay?) or how the air gets to the top of the engine nacelle behind the oil tank.

 

[Glider]

An improved Whirlwind, and Spitfire Mk. III's. Now THERE is a What If scenario for 1940!

Slapping some Merlin I's with big chin radiators on a Blenheim will make it go a little faster, but it is still dragging a bomber fuselage and wings through the air. It would still struggle to intercept the German Schnellbombers, or Ki-27 and G3M's in the far east. A lot of effort to bring a 15000 lb airplane into firing range, eventually, with just 4x .303 machine guns.
Maybe the bomb aimers position could be faired off, and replaced with a battery of Hispano's?

Some Blenheim fighters were equipped with a 20mm fitted in the nose.

 

[tomo pauk]

For the Whirlwind I can't find any photos of the air intake (inside the radiator bay?) or how the air gets to the top of the engine nacelle behind the oil tank

This is what I have:

 

[don4331]

Westland Whirlwind cutaway

I know the location of a Westland Whirlwind cutaway diagram. (sporting perigrine engines and 4 20mm cannons). In exchange for an HE-177 cutaway or Ki-44 Shoki cutaway, I could email it to you.

ww2aircraft.net

 

[Shortround6]

Thank you for the replies.
I am following a model build on

1/32 Westland Whirlwind

Here we go. My idea is to build a Special Hobby Whirlwind with both engines and nose guns open and exposed. problem: the whirlwind had Rolls Royce Peregrine engines and data on them is hard to find. Very hard to find… Special Hobby knows this and thats the reason they don’t offer an engine. i loo...

forum.largescalemodeller.com

which is not complete and yes it is a model.
But the builder is using a lot of documentation to detail the model and is 3D printing things like the engines, exhausts and oil tanks in the nacelle.
Unfortunately many of the photos/illustrations are rather large.
I have resized this one.

Basically it seems like the inlet duct has to go through the triangle shape in rib just over the tube that is part of the engine mount or it somehow has to come through the circular hole in the main spar after going through the rib.
Picture of model, also cropped/resized as original was 4000 pixels one way.

We can see the hole in the rib to the right of the engine, we can see the top of the carb, we can see the two holes in the spar. We can also see the room between the carb and the top of the cowl. Obviously they got the air to carb. The question is how much "RAM" did it have when it got there.
Model is not finished and perhaps there will be more detail reveled as the build is finished. Build started in Dec of 2023.

 

[tomo pauk]

IIRC the two circular holes were there because the original idea was that two exhaust manifolds are to be routed aft the nacelle.

Basically it seems like the inlet duct has to go through the triangle shape in rib just over the tube that is part of the engine mount or it somehow has to come through the circular hole in the main spar after going through the rib.

Seems like the duct in deed goes through the triangle hole in the spar, with it finally ending in the item 51 ( that seems like if some German spy designed it, leading the air without any curve in the carb intakes).
The final layout of exhausts is also kinda meh, with a good deal of exhaust stream going forward and then going back.

 

[Shortround6]

The final layout of exhausts is also kinda meh, with a good deal of exhaust stream going forward and then going back.

There a lot of detail about the exhausts in the model thread. It looks like the outlet is about where 2nd and 3rd (at best) exhaust ports are in the cylinder head. Unless there are interior partitions in that thing there are a lot conflicts in direction and flow. Cooling the exhaust gases may help with not setting fires and may help with less visible exhaust for night flying but it sure doesn't help with exhaust thrust.

It looks like the Whirlwind had poor propellers and a poor intake system for RAM and a poor exhaust system for thrust. No wonder it problems at altitude.

 

[MiTasol]

A recent exchange of letters published in "Aeroplane" magazine also referred to a whirlwind that was returned to Rolls Royce in an attempt to improve the power of the peregrine engines. Rolls Royce found that the air intakes to the engines were too small and followed a convoluted path , they modified the aircraft sent to them and gained a considerable increase in power. Apparently the modifications were dismissed by Westland because Rolls Royce were just car engine people and knew nothing about aeroplane construction. I think that it's great that you are building a Whirlwind and look forward to seeing it at Hawkinge.

I had never seen that quote but it is a classic example of Petter's attitude which is why I said that the Whirlwind needed to be taken away from him and given to someone else to debug and produce.

The hydraulic engine controls, the flaps interconnected with the cooling system causing engines to overheat and the dH props issue are well known but I was not aware of the induction problem. I have to admit that the Whirlwind has never been an aircraft that interested me so my knowledge on the type is minimal.

Petters dismissal of RR's findings is typical of his no-one knows as much as I do and no-one could improve anything I have designed attitude.

One article I saw many years ago said someone suggested replacing the off the shelf circular radiators with custom rectangular radiators to solve the overheating and that idea was treated like the RR finding.

As for the exhausts - they were no worse than what many Hawker and other aircraft had - it was an in thing for some reason for a while in Britain.

 

[Shortround6]

As for the exhausts - they were no worse than what many Hawker and other aircraft had - it was an in thing for some reason for a while in Britain.

This may be a result of tying to build flame suppression exhaust systems for night flying.
At least for fighters. This may date back to 1930 when they were asking for the exhaust glare to be out of the vision of the pilot. As much to cut down on crashes at night as much at increase chances of spotting an enemy aircraft. This tended to go in and out from time to time.
At times the exhaust system was just supposed to not kill the pilot/crew.
Good

bad

 

[MiTasol]

I was thinking more of these exhausts on the Hinds and Demons

 

[don4331]

The later C-47s (and a number of other radial engines) had sand filters installed at the rear of the inlet, the actual air inlet curved down a little earlier. The solid particles tended to go straighter and go through the curved slats at the sharp bend to the outside of the actual intake tract. There were different designs, sometimes the dirt trap was in front(?) like Martin Baltimores? Some P-38s had two inlets. The normal one on the outside of the cowl and an inner one with a filter that drew from the landing gear well. Obviously only used for take-off and landing but that is when dust/dirt was the worst.
Like a lot of other things they were learning a lot between 1936 and 1942-43 in regards to airflow and later installations that look similar from the outside may be a lot better than early installations. Larger passages and gentler bends can do a lot.

For the Whirlwind I can't find any photos of the air intake (inside the radiator bay?) or how the air gets to the top of the engine nacelle behind the oil tank.

Some views of the RR intake

The issue: While the RR intake allows the Peregrine to make full power, the drag of the intake makes the Whirlwind slow despite the extra power.
Hence the statement that RR should stick to designing cars.

Note the XP-47H had the same issue - without air scoops the Hemi wasn't able to make full power... With air scoops the Chrysler XIV-2220 made full power, but the plane was slower.

 

[tomo pauk]

The issue: While the RR intake allows the Peregrine to make full power, the drag of the intake makes the Whirlwind slow despite the extra power.
Hence the statement that RR should stick to designing cars.

Location of the oil tank made sure that such an air intake will stick out like a sore thumb, increasing the drag inordinately.
Relocate the oil tank and the air intake can go lower, in the upper cowling, like what the P-51s or P-40s had.

 

[MiTasol]

The brits always used short protruding high drag intakes like that one RR put on the Whirlwind

 

[Thumpalumpacus]

I am just an old firefighter but with water putting kinks and turns in hoses/pipes can lead to a lot of pressure/flow losses.
I imagine that air is the same. The Allison P-40 and P-51s had a really nice intake, Long and smooth with one roughly 90 degree turn into the carb.
109 used one 90 degree bend, Early Spitfire used one 90 degree bend

I'm not a motorhead and so I can't say much about the Peregrine, but kinks and turns in firehoses most assuredly weaken the output PSI at the nozzle. Air too is a fluid as well as a gas, and fluid dynamics applies to it as well. That includes friction-loss and induced turbulence.

A poorly-designed air-inlet (and I'm not saying this is so for the Peregrine, only making a general statement) will most certainly impede the inflow of air.