THE MYSTICAL MERLIN POWERED P-38

[SaparotRob]

The air at 20,000 feet is very cold the world over. There is no excuse for not designing proper cockpit heating for an aircraft designed for a service ceiling of over 30,000 feet.
This was not some unknown fact. The plot of the prewar movie Dive Bomber revolves around how cold it gets at altitude above sunny San Diego.

It's a must watch movie for a snapshot of USN aviation just before Peal Harbor.

I forgot how great that picture was. Thanks for the reminder.

 

[Reluctant Poster]

There is if the customer never specified a requirement for specific heating requirements!

At what altitudes do you think aerial combat was being undertaken in 1937????

The design spec for the P-38 (Circular Proposal X-608) only specified the aircraft must climb to 20,000 feet in six minutes. No one, to include Lockheed's initial and primary customer, the AAF ever thought the P-38 would be operating over 20,000, let alone 30,000 feet for sustained periods. It was designed as an interceptor, not a long range escort fighter!

Besides, Burbank is a lot warmer than San Diego! (Lived in SoCal for many years)

Kidding aside, it's amazing how the same aircraft was operated in Alaska and there's been little discussion about the cockpit heater from that theater!!!

What was not a known fact was what was going to happen in 5 years!

BTW, great movie! A young Fred MacMurray!

Its still below freezing at 10,000 feet.
As to blaming the customer, I work all the time with government agencies. The reason they hire me is that I know more about the subject than they do. I would fail in my duties as an engineer if I said; you didn't ask for heat tracing on your water lines so I didn't put it in. When the pipes burst I would be the one held responsible.
Specifications cannot cover everything. When I buy a big axial fan I don't expect the fan blades to be attached to the hub by duct tape because I didn't specifically ask for bolts. The manufacturer has more knowledge about his product that I do.

 

[GregP]

When they fixed the cockpit heat, it was simple ... install an electric heater! Duhhh ...

Wonder why it took so long?

 

[pbehn]

Were the bombers they escorted heated?

 

[tyrodtom]

Were the bombers they escorted heated?

If you mean the B-17s etc. no.
With all the gun slits in the turrets, and open waist positions, they'd be impossible to heat.
Or maybe the cockpit area only.
When you look at pictures of the crews, the pilots seem to be dressed lighter.

At some point they developed electrically heated longjohns. until that they bundled up.
When I was a kid, one of my uncles gave me the rheostat from one of those heated suits.

 

[Reluctant Poster]

Were the bombers they escorted heated?

Yes. Scroll to the bottom of the page to see a diagram of the B -17 cockpit heating system.
B-17G. Equipment. Turbo-superchargers.
The gunners were given electrically heated suits

 

[pbehn]

If you mean the B-17s etc. no.
With all the gun slits in the turrets, and open waist positions, they'd be impossible to heat.
Or maybe the cockpit area only.
When you look at pictures of the crews, the pilots seem to be dressed lighter.

At some point they developed electrically heated longjohns. until that they bundled up.
When I was a kid, one of my uncles gave me the rheostat from one of those heated suits.

It was a rhetorical question in a way. My uncle was invalided out of Bomber Command ops with severe lung problems before they introduced heated suits. All planes were different, some were uncomfortably hot for some of the crew near the hot air vent. Rear gunners routinely removed the Perspex in front of them so were in effect in an unheated bubble open to the air. I think the P-38 had its own problems because the pilot couldn't move, was on his own and missions became longer than anyone ordering and designing it could imagine.

 

[FLYBOYJ]

Its still below freezing at 10,000 feet.
As to blaming the customer, I work all the time with government agencies. The reason they hire me is that I know more about the subject than they do. I would fail in my duties as an engineer if I said; you didn't ask for heat tracing on your water lines so I didn't put it in. When the pipes burst I would be the one held responsible.
Specifications cannot cover everything. When I buy a big axial fan I don't expect the fan blades to be attached to the hub by duct tape because I didn't specifically ask for bolts. The manufacturer has more knowledge about his product that I do.

You still fail to recognize that this was in the late 1930s, the military aviation contracting world was in the stone age compared what is done today and I don't know if you worked in the aviation industry, so comparing this to your example is "apples and oranges." The customer sets the requirement and in most cases establishes internal equipment requirements. The P-38 was never designed to be produced in large numbers let alone operated in continual freezing weather, end of story. I have over 30 years working on aviation government contracts and there were many times when suggestions were made to the government (customer) and for one reason or another we were told to "design or work to the requirement." That's what happened here.

Early production P-38s did have a heater, obviously it was not adequate enough for operators in the ETO (although those operated in the Aleutians seemed to have no issues) and was improved later. If you look at heating systems for twin engine aircraft, it is difficult to bring diffused hot air into the cabin and I believe these systems were in their infancy when the P-38 was first designed and flown.

On 27 January 1939 the AAF accepted and flew the XP-38. If the aircraft wasn't to the requirement of Circular Proposal X-608, it would not have been accepted and Kelsey wouldn't have flown it. Later improvements came mainly from improvements required by the customer (based on operational requirements). That's the way it works in this industry unless there is incentive for the contractor to offer improvements and that concept is something that's only been put into affect in more recent times.

Below is a simple diagram of a reciprocating engine aircraft heating system.

Note where the "to cabin" duct is located. On early P-38s this duct had to run from the left engine IIRC through the wing into the fuselage gondola that housed the cockpit.

 

[FLYBOYJ]

When they fixed the cockpit heat, it was simple ... install an electric heater! Duhhh ...

Wonder why it took so long?

Ask the AAF!

The first 8AF P-38s didn't arrive until Sept 1943. Within 6 months with operational experience were issues addressed. BTW, the 8th AF was the only major command that complained about the P-38s heating system IIRC. Complaints justified but you can't blame the contractor retroactively for an issue that wasn't even thought of when the aircraft was first conceived.

 

[pbehn]

You still fail to recognize that this was in the late 1930s, the military aviation contracting world was in the stone age compared what is done today and I don't know if you worked in the aviation industry, so comparing this to your example is "apples and oranges." The customer sets the requirement and in most cases establishes internal equipment requirements. The P-38 was never designed to be produced in large numbers let alone operated in continual freezing weather, end of story. I have over 30 years working on aviation government contracts and there were many times when suggestions were made to the government (customer) and for one reason or another we were told to "design or work to the requirement." That's what happened here.

Early production P-38s did have a heater, obviously it was not adequate enough for operators in the ETO (although those operated in the Aleutians seemed to have no issues) and was improved later. If you look at heating systems for twin engine aircraft, it is difficult to bring diffused hot air into the cabin and I believe these systems were in their infancy when the P-38 was first designed and flown.

On 27 January 1939 the AAF accepted and flew the XP-38. If the aircraft wasn't to the requirement of Circular Proposal X-608, it would not have been accepted and Kelsey wouldn't have flown it. Later improvements came mainly from improvements required by the customer (based on operational requirements). That's the way it works in this industry unless there is incentive for the contractor to offer improvements and that concept is something that's only been put into affect in more recent times.

Below is a simple diagram of a reciprocating engine aircraft heating system.

View attachment 614975

Note where the "to cabin" duct is located. On early P-38s this duct had to run from the left engine IIRC through the wing into the fuselage gondola that housed the cockpit.

I can imagine the discussion in the late 1930s when someone said, "you will need a good cabin heater for all those long range, bomber escort missions you will be doing".

 

[FLYBOYJ]

I can imagine the discussion in the late 1930s when someone said, "you will need a good cabin heater for all those long range, bomber escort missions you will be doing".

My point!

 

[FLYBOYJ]

Yes. Scroll to the bottom of the page to see a diagram of the B -17 cockpit heating system.
B-17G. Equipment. Turbo-superchargers.
The gunners were given electrically heated suits

Those diagrams show the typical system and even then they weren't that efficient.

 

[tomo pauk]

Is the Circular Proposal X-608 available anywhere for download?

 

[FLYBOYJ]

Is the Circular Proposal X-608 available anywhere for download?

I've seen it on line once (didn't review it in detail) and could never find it again. I would love to find it again!!!

 

[tomo pauk]

I've seen it on line once (didn't review it in detail) and could never find it again. I would love to find it again!!!

A reason why I've asked is that internet is full of references to the Proposal, yet nobody seems to have ever read it. Thus we actually don't know the level of detail it went into.

 

[eagledad]

Gentlemen

On cabin heat:

There were complaints about cockpit heat listed in "Final Report on Tactical Suitability of P-38F Type Airplane" dated March 6th 1943. It is point b in Recommendations as found on Mike Williams and Neil Sterling's site.

The 7th Photo Recon Group was aware of the problems pilots had with the cold cockpits of their F5's by July of 1943. (See Eyes of the Eighth page 53).

It looks like a solution was "found" with the J-15 model, which I believe did not enter combat until early May in the ETO (corrections welcomed).
See
http://www.wwiiaircraftperformance.org/p-38/P-38J_performance_11march44.pdf

I agree that the P-38 was never envisioned to fly long periods of time at high altitude when first conceived and I am guessing its cockpit heating system was probably as good as any as any other multi-engine aircraft designed at that time.

My questions are,
Why did it take about a year to "fix" the problem?
How did heated flight suits fit into the fix?

Just thinking out loud.

Eagledad

Edit (It looks like a solution was "found" with the J-15 model, which I believe did not enter combat until early May in the ETO, changed late Feb early March to May)

 

[Shortround6]

I can imagine the discussion in the late 1930s when someone said, "you will need a good cabin heater for all those long range, bomber escort missions you will be doing".

Well, considering the original "Circular Proposal X-608" according to some books (not primary source) was for an interceptor with 2 hours of endurance the discussion about long range bomber escort may never have come up.
Especially when you consider that the P-38F was the first P-38 to be fitted with drop tanks. In fact the first 128 P-38Fs may not have had drop tanks as built (?). Some early P-38Fs were refitted after delivery.

 

[Reluctant Poster]

You still fail to recognize that this was in the late 1930s, the military aviation contracting world was in the stone age compared what is done today and I don't know if you worked in the aviation industry, so comparing this to your example is "apples and oranges." The customer sets the requirement and in most cases establishes internal equipment requirements. The P-38 was never designed to be produced in large numbers let alone operated in continual freezing weather, end of story. I have over 30 years working on aviation government contracts and there were many times when suggestions were made to the government (customer) and for one reason or another we were told to "design or work to the requirement." That's what happened here.

Early production P-38s did have a heater, obviously it was not adequate enough for operators in the ETO (although those operated in the Aleutians seemed to have no issues) and was improved later. If you look at heating systems for twin engine aircraft, it is difficult to bring diffused hot air into the cabin and I believe these systems were in their infancy when the P-38 was first designed and flown.

On 27 January 1939 the AAF accepted and flew the XP-38. If the aircraft wasn't to the requirement of Circular Proposal X-608, it would not have been accepted and Kelsey wouldn't have flown it. Later improvements came mainly from improvements required by the customer (based on operational requirements). That's the way it works in this industry unless there is incentive for the contractor to offer improvements and that concept is something that's only been put into affect in more recent times.

Below is a simple diagram of a reciprocating engine aircraft heating system.

View attachment 614975

Note where the "to cabin" duct is located. On early P-38s this duct had to run from the left engine IIRC through the wing into the fuselage gondola that housed the cockpit.

Dutch Harbor (rarely less than 22F) doesn't get much colder than Norwich (Rarely less than 27 F)

 

[FLYBOYJ]

Gentlemen

On cabin heat:

There were complaints about cockpit heat listed in "Final Report on Tactical Suitability of P-38F Type Airplane" dated March 6th 1943. It is point b in Recommendations as found on Mike Williams and Neil Sterling's site.

The 7th Photo Recon Group was aware of the problems pilots had with the cold cockpits of their F5's by July of 1943. (See Eyes of the Eighth page 53).

It looks like a solution was "found" with the J-15 model, which I believe did not enter combat until late February early March in the ETO (corrections welcomed).
See
http://www.wwiiaircraftperformance.org/p-38/P-38J_performance_11march44.pdf

I agree that the P-38 was never envisioned to fly long periods of time at high altitude when first conceived and I am guessing its cockpit heating system was probably as good as any as any other multi-engine aircraft designed at that time.

My questions are,
Why did it take about a year to "fix" the problem?
How did heated flight suits fit into the fix?

Just thinking out loud.

Eagledad

Excellent information! Thanks for posting!

From discussing this with folks from Lockheed when I worked there (about 37 years ago) the AAF had to order the re-design and put it in the contract. There were numerous other modifications going on at the time.

I knew a pilot who flew P-38s in the ETO (Mike Alba). He confirmed the heating issues with the P-38 and did say the heated suits did help a little but were "uncomfortable".

 

[FLYBOYJ]

Dutch Harbor (rarely less than 22F) doesn't get much colder than Norwich (Rarely less than 27 F)

Yes - and figure the lapse rate at 10,000'. Pretty cold - probably colder then what 8AF P-38 drivers were experiencing.