Improve That Design: How Aircraft Could Have Been Made Better

[GrauGeist]

In regards to Brewster amd their terrible production and quality control:
The company was not only mismanaged, but had poorly trained employees and disgruntled union members, who went on strike several times (which was illegal during wartime). The Navy stepped in, took control of the company in '42, but that didn't help things much.

Add to that, the Brewster's original manufacturing plant, which was an old auto manufacturing facility that was poorly suited for producing aircraft - in otherwords, as a plane was being manufactured, it had to be disassembled enough to move it to the next floor, reassembled and production continued until it needed to be moved to the next stage of assembly, which it then had to be partially disassembled in order to be moved along. Then they had to be shipped about 50 miles to the airfield, where they were finalized for delivery to the USN. This did not help the quality control nor was it very efficient time-wise.

An example of how bad things were; the Navy, after cancelling the Buccaneer contract, removed more than three hundred airframes from the plant and directly scrapped them.

It was just one great big mess all the way around.

 

[swampyankee]

Brewster is one of a (what's the antonym of elite?) small group of defense companies that managed to go out of business during wartime. This sort of management brilliance was probably not included in any MBA program as analyzing failure is not something those guys do.

 

[Zipper730]

Having worked in a classified project, I found it amazing what the military found necessary to classify. At the time, among other things that were classified were some of the computer programs, which were based on standard textbooks and readily available technical publications, many of which were from the USSR (there were a lot of articles from the Soviet equivalent of IEEE and APS; it was ironic that Cold War era stealth technology was so reliant on Soviet sources).

Weird that they'd classify things that are publicly available.

It is ironic that much of the knowledge of stealth came from the former Soviet Union. From what I recall, the problem was that they had trouble creating shapes that were stealthy that could also be made compatible with shapes that can fly.

what's the antonym of elite?

Dregs...

 

[Zipper730]

First, when Bell was asked to produce the jet, they were not told ANYTHING about the engine ... they got a big block of wood and were told the real engines would not be any bigger than the wood form block. But, and here's the part that most are missing, they were not told how much it would weigh, how much thrust it made, what the fuel consumption was, or where the engine mounts connected to the engines!

How does one design an airplane around that? It's vital to know about the propulsion system. The intakes have to be designed around how much airflow goes into them, while I am not hugely knowledgeable on reciprocating engines (despite them powering pretty much every single car on the road), you would assume the carburetor & radiator intakes would be sensitive to these issues (though I could be wrong).

It's one thing when you're building a bomber to carry a nuclear bomb: The bomb is usually carried on the center of gravity (that said, you'd still want decent figures for weight), and you can fly without it.

They COULD have done things differently

Could you give an example of how?

the US Government wasn't very big on sharing data such as the amount of intake air required at the time. Probably, they really didn't know.

I'm curious how the UK handled this matter? I know they developed a propulsion testbed (E.28/39) and the Gloster Meteor, of which both had jet-engines.

 

[Kevin J]

How does one design an airplane around that? It's vital to know about the propulsion system. The intakes have to be designed around how much airflow goes into them, while I am not hugely knowledgeable on reciprocating engines (despite them powering pretty much every single car on the road), you would assume the carburetor & radiator intakes would be sensitive to these issues (though I could be wrong).

It's one thing when you're building a bomber to carry a nuclear bomb: The bomb is usually carried on the center of gravity (that said, you'd still want decent figures for weight), and you can fly without it.
Could you give an example of how?
I'm curious how the UK handled this matter? I know they developed a propulsion testbed (E.28/39) and the Gloster Meteor, of which both had jet-engines.

The Meteor could handle whatever turbojets or turboprops were becoming available.

 

[Zipper730]

The Meteor could handle whatever turbojets or turboprops were becoming available.

So, the problem was that the RAF was telling the company what engines existed and more capability about what they could and could not do?

That and the engines were mounted on the wings in pods that could be more easily changed...

 

[davparlr]

Hey, Greg, how are you guys doing? I heard there was some rocking and rolling in your neck of the woods.

Broke my heart to hear about the crash of the N-9M and loss of the pilot.

The problems with the P-59 were more involved than what I am reading. We are restoring the 10th YP-59A to flight status and we have many documents.

It always is

First, when Bell was asked to produce the jet, they were not told ANYTHING about the engine ... they got a big block of wood and were told the real engines would not be any bigger than the wood form block. But, and here's the part that most are missing, they were not told how much it would weigh, how much thrust it made, what the fuel consumption was, or where the engine mounts connected to the engines! So, the engine compartment were made too large to accommodate whatever came along as an engine.

It is amazing that the military would foolishly not keep Bell updated on progress of the jet engine. An imbedded Bell engineer should have been keeping the aircraft engineers updated on the latest evolution of the I-16 engine.

The plane we have has engines that burn about 575 gallons per hour combined at low altitudes. It has less than 300 gallons of fuel, excluding the extra fuel tanks. Good luck with the range! It needs auxiliary tanks to have enough fuel to get around the pattern more than two or three times! The fuel consumption could be made to drop, but you'd use up the internal fuel just climbing up to any decent height making the extended climb a thing to avoid.

A comparison here of the YP-59A to the XP-80 (which flew a year later) is interesting and also the P-59B and the P-80A (both flown by end of war)

YP-59A
Gross weight 10,532 lb
Fuel Quantity 290 gallons
Engine/s two GE I-16 1600 lbs thrust, 3,200 lb total
Specific Fuel Consumption (SFC) 1.23
Top Speed 409 mph at 35,000 ft
Service Ceiling 43,200 ft

XP-80
Gross weight 8,916 lbs
Fuel Quantity 200-285 gallons
Engine one De Havilland Goblin H-1 total thrust 2,460 lbs
SFC 1.23
Top Speed 502 at 20,000 ft.
Service ceiling 41,800 ft.

As you can see here there is a slight difference between these two. The P-59 is slightly heavier but with 30% more thrust and a slightly higher ceiling. It also has more fuel. However, it is 100 mph slower. Fuel consumption (SFC) is identical, however the more powerful P-59 engines would use more fuel especially since the plane was very draggy.

P-59B
Gross weight 11,040 lbs
Fuel Quantity 365 gallons
Engine two GE J-31 (I-20) 2000 lb thrust each 4,000 lb total
Engine weight 902 lbs, total 1804
SFC 1.2
Top speed 413 mph at 30,000 ft
Service ceiling 46,200

P-80A
Gross weight 11,700 lbs
Fuel quantity 470 gallons
Engine one Allison J33 4,000 lb thrust total
Engine weight 1,850 lbs
SFC 1.19
Top Speed 558 mph at SL, 508 at 30,000 ft
Service ceiling 45,000 ft.

These two planes are also similar, similar weight and thrust and SFC. P-80 has almost 30% more fuel. Again, the P-80 is almost 100 mph faster at 30,000 ft. probably more at SL. Fuel consumption was an issue on all the early jet engines. Its obvious that the main issue is the drag on the P-59, mainly due to the wing design.

If you DID get above 35,000 feet, the canopy would freeze over from the inside! If you open the canopy in flight, you can't get it closed! The roll rate was VERY slow, and would have been difficult to improve. The aileron gap seals were quite long (and still are), and the ailerons only had about 11° - 13° of movement in them at full deflection! The aileron tabs were servo tabs ... we have changed them to anti-servo tabs to get maybe a bit more roll rate at the expense of a slightly heavier stick. Our plane will be an airshow machine only, and it won't ever go very fast.

Except for the canopy, my new wing would fix this.

There is NOTHING on the YP-59A that is easy to work on, and changing engines is not a fun task.

I suspect product schedule pressure negated desire to build to maintainability.

Overall, I suspect all of these issues could be address successfully and time to do so if there was a desire. However, in 1942-43, I think there was a general apathy in the US to work jet issues. In 1944 with the advent of the Me 262, priorities changed. The AAF did not want to fix an old and slow airplane, they wanted a new one, and they got a good one.

 

[Zipper730]

It is amazing that the military would foolishly not keep Bell updated on progress of the jet engine.

I'd say so, especially when you consider that we started developing a jet engine because the British and Germans were developing the designs. In other words, we were behind the curve, so that means we don't have to keep as many secrets as say, the UK or Germans, because they were ahead of the curve.

An imbedded Bell engineer should have been keeping the aircraft engineers updated on the latest evolution of the I-16 engine.

When you say that, you mean the engineer would be specially briefed and "read in", and he would be allowed to give data as needed?

I suspect product schedule pressure negated desire to build to maintainability.

The P-59 served two purposes, as I understand it: Firstly, to be a proof of concept for jet powered aircraft/fighters; secondly: To be a functional jet fighter.

It at least met the first goal, and it flew fast enough to show the benefit of jet-engines (375 mph IIRC 1 lbf = 1hp)

Overall, I suspect all of these issues could be address successfully and time to do so if there was a desire. However, in 1942-43, I think there was a general apathy in the US to work jet issues.

I always found that surprising...

 

[P-39 Expert]

Supposednly the engines didn't deliver the advertised thrust also.

 

[Shortround6]

I think there was a general apathy in the US to work jet issues

I am not sure about that given the total number of engine projects being worked on. However some of them never produced working hardware (or at least worked well enough to get off the test bench) so the effort gets a bit short changed in many popular histories.

Nathan Price started work in 1938, he went to work for Lockheed but the over ambitious L-1000 engine sucked up a lot of time for little result.

Vladimir Pavlecka had gone to work for Northrop in 1939 with the idea of developing a turbo prop, they got money from both the army and navy in 1941.

The NACA was fooling around with ducted fans.

By Sept 1941 GE had to projects going, the Whittle type engines at Lynn and an axial flow turbo prop at Schenectady.

P&W had started work on 5000hp turbo prop in May of 1941. They stopped work in June 1945 after spending 3.3 million dollars.

Allis-Chalmers was involved in several projects but they led to no real practical results (they may have been the Brewster of Jet engines)

Westinghouse got contracts to build a jet engine (axial) in Jan 1942.

One thing (out of a number of things) that hindered US progress was the Army's insistence that everything be top secret. So much so that the two GE programs were not allowed to talk to each other let alone any company talk to another company. There was a lot of needless duplication of effort in things like burner cans, igniters, bearings and lubrication, fuel management and so on.

 

[Zipper730]

I am not sure about that given the total number of engine projects being worked on. However some of them never produced working hardware (or at least worked well enough to get off the test bench) so the effort gets a bit short changed in many popular histories.

True

Nathan Price started work in 1938, he went to work for Lockheed but the over ambitious L-1000 engine sucked up a lot of time for little result.

I'm amazed at the overly complex nature of the engine. It was too complex to begin with, and became increasingly absurd around requirements that weren't necessary for the engine

1. They either miscalculated the efficiency of the engine, were trying to get more power than they really needed, or both
   • The earliest design had an axial flow compressor feeding a reciprocating compressor, with an afterburner: It didn't seem to go far
   • The second design incorporated a mixed-flow arrangement
     • The reciprocating compressor was replaced with a three-staged centrifugal-flow section
     • The first compressor stage was variable-pitched in configuration
     • Intercooling was placed between the axial and centrifugal compressors; provision also existed for intercooling between at at least two of the three centrifugal flow stages.
     • The engines were "handed" something that's not needed in jets
     • The engines were fitted with a differential gearing and hydraulic coupling to allow the adjustment of the RPM, so it can operate a boundary-layer control system. I'm not sure if this was something Mr. Price was looking at himself, or Lockheed took a serious interest in.
   • The third design incorporated a twin-spool arrangement
     • 32-stages of compressor blades divided across two 16-stage shafts
     • The first four blades on the LP shaft was effectively hydraulically clutched
     • Intercooling was retained, and positioned between the LP & HP shafts
     • The engine was now fitted with an annular combustion chamber
     • The afterburner used a regeneratively cooled configuration from what I remember
2. They designed the engines around qualities that might not have been planned in the aircraft, such as laminar flow control
3. They seemed to not quite factor in the fact that fuel burn drops quite a bit as you go higher, and ram-compression adds quite a bit of performance to the engine

Vladimir Pavlecka had gone to work for Northrop in 1939 with the idea of developing a turboprop, they got money from both the army and navy in 1941.

Still an improvement over a piston driven engine. His design was axial flow, and would have easily laid the way for turbojet development.

The NACA was fooling around with ducted fans.

They really had a predilection for that over a turbojet. They seemed to be preoccupied with that over a gas-turbine. Fro what I remember, the rationale was as follows

1. Edgar Buckingham's Report: It wasn't about a gas-turbine, but about a piston engine producing all it's power in the form of thrust instead of driving a propeller
   • His expectations were for exhaust-velocities as high as 5280 fps: Higher exhaust velocities work terribly at lower speeds and, while I don't know the exhaust stack airflow velocity, considering that 375 mph results in 1 hp / 1 lbf: I would be lead to assume that the velocities would be similar to gas-turbines
   • His expectations called for pressure-ratios of around 15-30, which would hinge upon gear-driven or exhaust-driven superchargers: Most early jet-engines had pressure ratios that were around 3.5-4.0. I'm not sure when we would see pressure ratios of 15-30 to 1.
   • While he factored in ram-compression reducing the required engine-size: He did not factor in speeds above 250 mph, and speeds of that figure were already being approached, reached, or exceeded in 1923.
2. Gas-turbines were believed to be grossly overweight: This seemed to have not been understood as well as it should be -- it seems many steam turbines were big because they were designed for power-generation, not an inherent fault in the design of the engine.

One thing (out of a number of things) that hindered US progress was the Army's insistence that everything be top secret. So much so that the two GE programs were not allowed to talk to each other let alone any company talk to another company. There was a lot of needless duplication of effort in things like burner cans, igniters, bearings and lubrication, fuel management and so on.

The problem is how does one balance secrecy, with the ability to coordinate efforts? You'd think there'd be some guy who's in charge of everything and he manages all the projects.

 

[GrauGeist]

One thing (out of a number of things) that hindered US progress was the Army's insistence that everything be top secret. So much so that the two GE programs were not allowed to talk to each other let alone any company talk to another company. There was a lot of needless duplication of effort in things like burner cans, igniters, bearings and lubrication, fuel management and so on.

Which is one of the reasons the P-59A was never able to live up to it's full potential. It was literally built around an imaginary engine (as Greg noted) and so it had considerable flaws as a result.
The interesting fact here, is that the P-59A first flew in October 1942 - just a few months after the Me262 (V3) first flew under jet power - and almost 6 months before the Meteor first flew.
And *if* the Army had dropped all the cloak & dagger stuff and been a little more forthcoming with the engine details, the Airacomet may have not only been able to perform better, but it's teething troubles would have been far lesser resulting in a shorter maturation time and it most likely could have been seen in Europe's skies as a result.

 

[Mad Dog]

….The .5in Vickers was large, heavy and suffered from jams even though it rarely actually broke. (How do you define reliability?) it also didn't have a particularly high rate of fire. Provision of truly effective ammo was a problem, No HE rounds and good incendiaries only came later?....

For the Army, the sole reason for the Vickers .5 was to provide a punchier companion to the Vickers .303, and firing only AP ammo. There was no driver to produce a SAPI round as far as the Army was concerned. The Royal Navy did have a reason as they used the Vickers .5 in quad mountings as a close-in air defence weapon, but they decided to upgrade to the Oerlikon 20mm cannon instead. The RN also used a SAP round as it was almost as effective as the AP round and cheaper to make. Kynoch had developed a SAP-T round in 1935 but the MoD didn't buy it for the Army, but the RN did. Rate of fire was 750rpm, which was higher than the Hispano.
If the RAF had decided to go with the air-cooled Vickers .5 in the '30s, then they could have quite easily scaled up the existing .303 incendiary and tracers, and produced a de Wilde/Dixon SAPI round in 1940. Which suggest the RAF could easily have had an air-cooled Vickers .5 version, firing HE, SAPI, SAP and SAP-T in time for the Battle of Britain. They could even have copied the Italian .5 HE bullet seeing as the Italian round was a Vickers modification of their .5 round, or scaled up the .303 HE rounds like the Pomeroy type. Good info on actual Vickers .5 ammo here and info on the Vickers here

 

[PAT303]

For the Army, the sole reason for the Vickers .5 was to provide a punchier companion to the Vickers .303, and firing only AP ammo. There was no driver to produce a SAPI round as far as the Army was concerned. The Royal Navy did have a reason as they used the Vickers .5 in quad mountings as a close-in air defence weapon, but they decided to upgrade to the Oerlikon 20mm cannon instead. The RN also used a SAP round as it was almost as effective as the AP round and cheaper to make. Kynoch had developed a SAP-T round in 1935 but the MoD didn't buy it for the Army, but the RN did. Rate of fire was 750rpm, which was higher than the Hispano.
If the RAF had decided to go with the air-cooled Vickers .5 in the '30s, then they could have quite easily scaled up the existing .303 incendiary and tracers, and produced a de Wilde/Dixon SAPI round in 1940. Which suggest the RAF could easily have had an air-cooled Vickers .5 version, firing HE, SAPI, SAP and SAP-T in time for the Battle of Britain. They could even have copied the Italian .5 HE bullet seeing as the Italian round was a Vickers modification of their .5 round, or scaled up the .303 HE rounds like the Pomeroy type. Good info on actual Vickers .5 ammo here and info on the Vickers here

Your forgetting the biggest issue with aircraft weapons which is how they perform once installed and under G load. Look at the Hispano and Browning .50 as examples, on a fixed mount both worked perfectly, in a twisting wing under G load both fared poorly, the RAF used .303 brownings because they worked all the time every time throughout the war, the Hispano and BMG were more effective weapons but both required lots of debugging before they got there, there's nothing to suggest the .5 Vickers would be any different. Interesting enough both the .50's ended up using scaled up versions of .303 ammunition which means fighting the BoB with cup and core ball ammo if they were adopted, in my opinion it would have been better to stick with what works, the .303 brownings and devote time and money in producing more specialised De-Wilde/Dixon/AP ammunition than a whole new gun system.

 

[Shortround6]

The trouble with the .5in Vickers was that it was a Vickers, with all the good and bad that came with it. Vickers guns are reputed to break very seldom and last for tens of thousands of rounds (if not hundreds of thousands given barrel changes) but are subject to a large variety of jams/malfunctions, most of which can be cleared quickly if the gunner has access to the gun which in a wing mount he does not. This was the impetus for adopting the Browning, getting a gun that could be mounted away from the pilot or crew. There is no reason to believe the Big Vickers would be any better than the small Vickers in this regard and indeed a few tales from the Royal Armoured Corp with .5in Vickers in one man turrets suggest that the gun was harder to work on than the smaller gun due to the confined space.

the 2nd problem with the Vickers is that for some reason it had a lower rate of fire than the Brownings. The best they got out of a rifle caliber Vickers seems to be about 900rpm with synchronization while the small Browning could hit 1200rpm (or higher in experiments), The best out of the Big Vickers seems to be 700rpm? The Japanese got 900rpm out of their Browning copy (unsynchronized) and the Americans got 800rpm or better from the M2 in late 1940 or early 41.

Firing AP bullets the numbers don't look good for the big Vickers. since you can mount two .303 Brownings for the weight of a single .5in Vickers (?) the two Brownings can deliver 448 grams of projectiles per second (40 bullets) vs the 424 grams or less for the .5in Vickers (figured 12 bullets per second/720rpm) The .50 Browning used significantly heavier bullets than the .5in Vickers.
We can try comparing the amount of incendiary material thrown another time but you need to push the firing rate of the gun (of whatever action) using the .5 Vickers ammo to 900rpm to get even an 18% increase in throw weight over the pair of .303 Brownings (which are still lighter and use lighter Ammo. ) how much of an improvement do you need to make a change?

 

[P-39 Expert]

The trouble with the .5in Vickers was that it was a Vickers, with all the good and bad that came with it. Vickers guns are reputed to break very seldom and last for tens of thousands of rounds (if not hundreds of thousands given barrel changes) but are subject to a large variety of jams/malfunctions, most of which can be cleared quickly if the gunner has access to the gun which in a wing mount he does not. This was the impetus for adopting the Browning, getting a gun that could be mounted away from the pilot or crew. There is no reason to believe the Big Vickers would be any better than the small Vickers in this regard and indeed a few tales from the Royal Armoured Corp with .5in Vickers in one man turrets suggest that the gun was harder to work on than the smaller gun due to the confined space.

the 2nd problem with the Vickers is that for some reason it had a lower rate of fire than the Brownings. The best they got out of a rifle caliber Vickers seems to be about 900rpm with synchronization while the small Browning could hit 1200rpm (or higher in experiments), The best out of the Big Vickers seems to be 700rpm? The Japanese got 900rpm out of their Browning copy (unsynchronized) and the Americans got 800rpm or better from the M2 in late 1940 or early 41.

Firing AP bullets the numbers don't look good for the big Vickers. since you can mount two .303 Brownings for the weight of a single .5in Vickers (?) the two Brownings can deliver 448 grams of projectiles per second (40 bullets) vs the 424 grams or less for the .5in Vickers (figured 12 bullets per second/720rpm) The .50 Browning used significantly heavier bullets than the .5in Vickers.
We can try comparing the amount of incendiary material thrown another time but you need to push the firing rate of the gun (of whatever action) using the .5 Vickers ammo to 900rpm to get even an 18% increase in throw weight over the pair of .303 Brownings (which are still lighter and use lighter Ammo. ) how much of an improvement do you need to make a change?

You have mentioned before how the Browning .50 improved throughout the war, could you point me to a post that summarizes that? Is that why often the rate of fire is quoted as a range (600-720)? How much did synchronization through the propeller reduce the rate of fire? Thanks.

 

[swampyankee]

You have mentioned before how the Browning .50 improved throughout the war, could you point me to a post that summarizes that? Is that why often the rate of fire is quoted as a range (600-720)? How much did synchronization through the propeller reduce the rate of fire? Thanks.

According to Tony Williams "tests of cowling-mounted .50M2 in US aircraft revealed RoFs of 400–450 rpm " http://www.quarryhs.co.uk/Synchro.pdf

 

[Shortround6]

You have mentioned before how the Browning .50 improved throughout the war, could you point me to a post that summarizes that? Is that why often the rate of fire is quoted as a range (600-720)? How much did synchronization through the propeller reduce the rate of fire? Thanks.

actually the early guns (up to some point in 1940) fired at 500-600rpm, this is with short belts and on a test stand with no extra G's causing extra belt drag. The rate of fire was boosted to 750-850rpm at some point in 1940, I don't know what month. The older guns could be brought up to the new standard with a parts kit. At some point they changed the feed cam trackway and doubled the amount of pull the gun exerted on the belt to help with some of the feed problems. All guns fired over a range as even guns built hours apart on the same production line have slightly different weight bolts, different "fit" (even a few thousands of in inch difference in clearance) and slightly different strength springs.

As shown in the link provided by Swampyankee synchronization could affect some guns more than others but the Browning .50 seemed particularly affected.
The other major change was that the ammo changed right before the war and then the provision of different bullets during the war.

 

[P-39 Expert]

Thanks for the info. So from about 1941 through the rest of WWII the .50 remained about the same?

 

[davparlr]

I am not sure about that given the total number of engine projects being worked on. However some of them never produced working hardware (or at least worked well enough to get off the test bench) so the effort gets a bit short changed in many popular histories.

Perhaps I should have said "jet aircraft" issues. They had originally designed the P-59 to be upgraded to a fighter, better than projected prop jobs. They knew immediately that the plane was not capable of that yet they seemed not to be particularly interested in upgrading performance, like replacing the wing. The Me 262 had flown only a few months ahead of the P-59 but was still able to make significant changes (like getting the main landing gear behind the center of gravity, gotta be major wing modification, and installing a nose gear, another major modification) and addressing the various propulsion issues that all had to face in the early days, and still make combat in spring of '44. The Germans did have an advantage of knowing what they wanted out of a jet plane and had more expertise behind them. Still determining why the plane was such a poor performer and fixing it didn't seem to fit the equations (it had more thrust available than the 100 mph faster He 280). I think the general philosophy of the military at this time was "better is the enemy of good enough" and in 1942 they had designs that were good enough and didn't stress fixing the P-59 (maybe also affecting the design of the T-26 tank and larger bazooka, and others) . Secrecy may have played into this however redesigning the wing would not have been a problem, allocated money may have been. I still think they might have slapped on the P-63 wing and gotten significantly better performance.
There just didn't seem to be pressure to make it work as there was in Germany, and England.