Curtiss XP-37/YP-37

[wuzak]

In any case, the IV-1430 was being developed at the behest of the USAAC, while the O-1230 was largely a private venture. In that case it is hard for the government to kill one, while not wanting to kill the other.

The O-1230 however did work though correct?

Yes, it worked.

The O-1230 was developed by Lycoming, but the IV-1430 started life (on paper) as an O-1230, before becoming an O-1430 and then the IV-1430.

Okay, I gotcha.  Why did they go from O-1430 to IV-1430?  And why did they feel the O-1430 had enough potential to consider justification?

Tomo covered this earlier. The opposed engine was for buried installation in bombers, to theoretically cut down on drag.

Things like wheel stowage meant that, practically speaking, there was no benefit. So it was redesigned as an inverted V-12, as someone in the army thought that was the best layout.

The project was the army's baby, so there was the justification.

Out of curiosity, why did they focus on HP/Cubic Inch instead of HP/Pound?

No idea. Probably just seeing what they could get out of a certain displacement.

The Continental and Lycoming engines were based on the "Hyper" cylinder developed at the Engineering Division of the USAAC in the late 1920s. No coincidence that they had the same capacity (initially).

The goal of the hyper-project was over 1 hp per cubic inch of cylinder based around the idea of a sleeve-valved engine?

I gave you incorrect information earlier. The original Continental engine was 1,008ci, then enlarged to 1,425ci.

The hyper engines did not feature sleeve valves.

Allison

• V-3420: First proposed in 1934, first run in 1937, first suitable for use in 1942-1943?
  

The V-3420 was first proposed as an X-3420 with a single crankshaft, but using pistons, cylinder blocks, heads, etc, from the V-1710. It later was proposed to be what it became - essentially two V-1710s joined together.

Continental

• IV-1430: Begun in 1932, became IV-1430 in 1934?
  
• O-1430: Begun in 1938
  
• XH-2860: Designed, but I'm unsure if it was built
  

The IV-1430 began life in 1932 as the 1,008ci engine then quickly becoming the O-1430. Single cylinder development continued until 1938.

To put that in perspective, the Merlin started life at around the same time, was run as a V-12 in 1933 and was in production in 1937.

Never heard of the XH-2860. I doubt it ever existed, even in people's minds, as the O-1430 was redesigned to the IV-1430.

Pratt & Whitney

• X-1800 (H-2240): Developed in the 1938-1940 period; eventually enlarged to 2597.7 (H-2600)
  
• XH-3130: Developed in the late 1930's; eventually enlarged into the XH-3730 and cancelled in 1940 in favor of the Wasp-Major (I think that was a good choice)
  

Pratt & Whitney's sleeve valve projects were driven by George Mead, whose health deteriorated until he quit the company. After which the X-1800 (XH-2600) was cancelled in favour of the R-4360.

The XH-3730 wasn't cancelled until 1943.

Wright

• R-2160 Tornado: Proposed in 1940, first used in 1944
  

The Tornado was first proposed in 1938 and cancelled in early 1944.

The 14 cylinder test engine (T-14) first ran in 1940.

The full engine (T-42) ran maybe in 1941.

The Tornado wasn't "used" as such. It only ran on the test bench, and there were many issues with it.

No, two speed prop drive.

To permit more efficiency for cruise and more power for takeoff?

Isn't that what I said?

[KJ_Lesnick]

wuzak

Yes, it worked.

That's good to know!

The opposed engine was for buried installation in bombers, to theoretically cut down on drag.

The NACA Cowling began to equip every radial from 1932 on right?

So it was redesigned as an inverted V-12, as someone in the army thought that was the best layout.

Makes sense

The project was the army's baby, so there was the justification.

Bureaucratic inertia...

No idea. Probably just seeing what they could get out of a certain displacement.

While I could sort of understand trying to squeeze as much out of as little, the ironic thing is that power to weight is a more important measurement LOL.

The hyper engines did not feature sleeve valves.

Really?  Then why was that mentioned in the development history?

The V-3420 was first proposed as an X-3420 with a single crankshaft, but using pistons, cylinder blocks, heads, etc, from the V-1710. It later was proposed to be what it became - essentially two V-1710s joined together.

That I did not know: Why did they go with a W instead of an X?

The IV-1430 began life in 1932 as the 1,008ci engine then quickly becoming the O-1430. Single cylinder development continued until 1938.

Understood

To put that in perspective, the Merlin started life at around the same time, was run as a V-12 in 1933 and was in production in 1937.

Yeah, the UK seemed to either have a better budget or more money allocated to engines...

Never heard of the XH-2860. I doubt it ever existed, even in people's minds, as the O-1430 was redesigned to the IV-1430.

I just compiled a list -- it appeared to have been something drawn up but it's unlikely it was built.

Pratt & Whitney's sleeve valve projects were driven by George Mead, whose health deteriorated until he quit the company. After which the X-1800 (XH-2600) was cancelled in favour of the R-4360.

I didn't know that, but the R-4360 was cooked up in 1940?

The XH-3730 wasn't cancelled until 1943.

Now that I didn't know, but nice to know though 

The Tornado was first proposed in 1938 and cancelled in early 1944.

The 14 cylinder test engine (T-14) first ran in 1940.

The full engine (T-42) ran maybe in 1941.

The Tornado wasn't "used" as such. It only ran on the test bench, and there were many issues with it.

So, it was impractical or unreliable?

[wuzak]

The hyper engines did not feature sleeve valves.

Really?  Then why was that mentioned in the development history?

What development history?

The V-3420 was first proposed as an X-3420 with a single crankshaft, but using pistons, cylinder blocks, heads, etc, from the V-1710. It later was proposed to be what it became - essentially two V-1710s joined together.

That I did not know: Why did they go with a W instead of an X?

They were able to use more common parts. And reduced design time - they didn't have to design a master and slave rod arrangement.

To put that in perspective, the Merlin started life at around the same time, was run as a V-12 in 1933 and was in production in 1937.

Yeah, the UK seemed to either have a better budget or more money allocated to engines...

I don't know if it was about money.

Rolls-Royce started the Merlin as a private venture, tipping a lot of their own cash into the project. In contrast the IV-1430 program was dictated by the government and its purchasing processes.

There was also the slight matter of urgency in the UK that didn't exist in the US in the mid 1930s.

The Tornado was first proposed in 1938 and cancelled in early 1944.

The 14 cylinder test engine (T-14) first ran in 1940.

The full engine (T-42) ran maybe in 1941.

The Tornado wasn't "used" as such. It only ran on the test bench, and there were many issues with it.

So, it was impractical or unreliable?

There were issues with the design.

But Wright had not enough resources to devote to it, as they were still trying to debug the R-3350 at the same time.

[KJ_Lesnick]

What development history?

https://en.wikipedia.org/wiki/Continental_XI-1430 there was a mention of sleeve valves

They were able to use more common parts. And reduced design time - they didn't have to design a master and slave rod arrangement.

They didn't realize this early on I would guess?

I don't know if it was about money.

Rolls-Royce started the Merlin as a private venture, tipping a lot of their own cash into the project. In contrast the IV-1430 program was dictated by the government and its purchasing processes.

There was also the slight matter of urgency in the UK that didn't exist in the US in the mid 1930s.

1. When you say urgency, do you mean the build up to war with Germany?

2. What government practices screwed it up?

There were issues with the design.

What issues?

[wuzak]

What development history?

https://en.wikipedia.org/wiki/Continental_XI-1430 there was a mention of sleeve valves

In the late 1920s Harry Ricardo wrote a paper on the sleeve valve design that led to the USAAC's hyper engine efforts. He [Ricardo] claimed that the 1 hp/in³ goal was impossible to achieve with poppet valve type engines. The USAAC engineering team at Wright Field decided to test this claim by beating it.

This is the part to which you refer. It mentions a claim made by Ricardo about poppet valve engines not being able to get the 1hp/ci mark, and then states that the USAAC determined to prove him wrong.

They were able to use more common parts. And reduced design time - they didn't have to design a master and slave rod arrangement.

They didn't realize this early on I would guess?

The USAAC asked them for an X engine that would use V-1710 blocks.

Allison later suggested that the double Vee was a better solution.

I don't know if it was about money.

Rolls-Royce started the Merlin as a private venture, tipping a lot of their own cash into the project. In contrast the IV-1430 program was dictated by the government and its purchasing processes.

There was also the slight matter of urgency in the UK that didn't exist in the US in the mid 1930s.

1. When you say urgency, do you mean the build up to war with Germany?

2. What government practices screwed it up?

Yes, the deteriorating political situation in Europe was a driving force behind the RAF's rearmament.

It was said earlier. Each stage of development went through a procurement process. Unlike most programs where the procurement is for the finished product.

There were issues with the design.

What issues?

There were a lot of issues.

[KJ_Lesnick]

wuzak

This is the part to which you refer. It mentions a claim made by Ricardo about poppet valve engines not being able to get the 1hp/ci mark, and then states that the USAAC determined to prove him wrong.

And others started working on sleeve valves

The USAAC asked them for an X engine that would use V-1710 blocks.

Why did they suggest an X over a W?

It was said earlier. Each stage of development went through a procurement process. Unlike most programs where the procurement is for the finished product.

Strange layout if you ask me...

There were a lot of issues

We're just going in circles... could you list one for instance?

[wuzak]

This is the part to which you refer. It mentions a claim made by Ricardo about poppet valve engines not being able to get the 1hp/ci mark, and then states that the USAAC determined to prove him wrong.

And others started working on sleeve valves

The hyper engine program had nothing whatsoever to do with sleeve valves.

You are having a failure of comprehension.

The hyper program was a cylinder design featuring 2 OHV per liquid cooled cylinder, in an hemispherical combustion chamber.

The hyper engine family used these features and separate cylinder construction as identifiable features.

A family of sleeve valve engines was designed and built by Pratt & Whitney off their own bat, driven by George Mead who had been impressed by the Napier Sabre. It had nothing to do with hyper engines.

The British were not involved in the hyper program, and it is they who built most of teh sleeve valev engines - production or otherwise.

The USAAC asked them for an X engine that would use V-1710 blocks.

Why did they suggest an X over a W?

An X is more compact.

Allison had built the X-4520 to a USAAC design in the '20s.

It was said earlier. Each stage of development went through a procurement process. Unlike most programs where the procurement is for the finished product.

Strange layout if you ask me...

Well, yeah.

There were a lot of issues

We're just going in circles... could you list one for instance?

The proximity of the exhaust and intake manifolds.

[KJ_Lesnick]

wuzak

The hyper engine program had nothing whatsoever to do with sleeve valves.

You are having a failure of comprehension.

No, I get it: The hyper engine did not use sleeve valves, though other people did (it wasn't part of the hyper design).

An X is more compact.

Why didn't they just issue an RFP for a high-power engine-design using of 2 x V-1710 blocks, ask them to submit the possible layouts; then select the arrangement that worked best?  The manufacturers often knew what they were doing and could pick the best arrangement and if the USAAC makes the final call, then you win either way.

As for the need to design a new master/slave-rod arrangement: Why didn't they realize this problem would occur?  Was it just because Allison made it work before on the X-4520?  While I'm at it was there a V-2260?
   

Well, yeah.

Why did they lay out such a strange process?  Was this a purely experimental engine -- if so why didn't they start with something smaller; then issue an RFP for a larger scale?

The proximity of the exhaust and intake manifolds.

Too close?

[wuzak]

An X is more compact.

Why didn't they just issue an RFP for a high-power engine-design using of 2 x V-1710 blocks, ask them to submit the possible layouts; then select the arrangement that worked best?  The manufacturers often knew what they were doing and could pick the best arrangement and if the USAAC makes the final call, then you win either way.

They requested a single crank engine using 4 V-1710 cylinder banks.

It was a change in chief designer that led to the V-3420.

As for the need to design a new master/slave-rod arrangement: Why didn't they realize this problem would occur?  Was it just because Allison made it work before on the X-4520?  While I'm at it was there a V-2260?

The X-4520 did not use a master and slave rod arrangement, Allison did not do the design (at least the initial design) and there was no V-2260.

https://oldmachinepress.wordpress.com/2013/06/16/allison-x-4520-24-cylinder-aircraft-engine/

Well, yeah.

Why did they lay out such a strange process?  Was this a purely experimental engine -- if so why didn't they start with something smaller; then issue an RFP for a larger scale?

It was a bureaucracy.

As for starting with something smaller, they did 6 years of single cylinder development.

The proximity of the exhaust and intake manifolds.

Too close?

It was a small diameter 7 cylinder radial with 6 rows.

It was basically three 14 cylinder radials geared together with 7 layshafts driving the reduction gear.

http://www.williammaloney.com/aviation/AviationHallOfFameTeterboroNJ/AircraftEngines/images/09WrightTornadoR2160.jpg
http://www.weakforcepress.com/TornadoWP1280.jpg
https://www.youtube.com/watch?v=9PydBh1NhLA

[KJ_Lesnick]

wuzak

They requested a single crank engine using 4 V-1710 cylinder banks.

Okay, that makes more sense

It was a change in chief designer that led to the V-3420.

So they just based it around what made the most sense (compactness), or based on previous experience with the X-4520?

While on this subject: The X-3420 started in 1934, when did it switch to the V-3420?

The X-4520 did not use a master and slave rod arrangement

Why would the V-3420 need one then?  Was it due to using two engines as one?

Allison did not do the design (at least the initial design) and there was no V-2260.

So the US Army came up with the basic design; then told them to refine it into something that would work and submit the proposal?  Was this how the United States did things as a rule?

It was a bureaucracy.

I'm also curious about the delay in going from O-1230, to the O-1430, to the I-1430 even despite the fact that the NACA cowling was created in 1929, and began to equip aircraft from 1932 on, and the design began in 1932: I'm curious how much multi-disciplanary skill did engine designers have with the rest of the airframe integration? For example did the guys designing the engines understand development changes in radiator and cowling designs?

I know there was a problem in the US with multi-disciplinary work which supposedly lead to delays in jet-engine development.

As for starting with something smaller, they did 6 years of single cylinder development.

You mean along with the engine right?

It was a small diameter 7 cylinder radial with 6 rows.

So the RPM would be higher than a 3-row radial with 14 cylinders?

7 layshafts driving the reduction gear

That's to change the RPM down to something remotely reasonable I would guess?

[wuzak]

The X-3420 started in 1934, when did it switch to the V-3420?

~1937

The X-4520 did not use a master and slave rod arrangement

Why would the V-3420 need one then?  Was it due to using two engines as one?

As the X-4520 was designed from the outset as an X, and it was air cooled, its bore spacings could be made to allow for the space for side by side fork and blade rods. It meant that the lower banks were offset from teh upper banks and the engine was slightly longer.

The X3420 was to use existing V-1710 cylinder blocks and heads, and was thus stuck with the same cylinder spacing. To use side by side fork and blade connecting rods would have meant the connecting rods weren't strong enough or the crank wasn't strong enough or both.

The V-1710 crank
http://www.oldengine.org/members/diesel/duxford/Allison5.jpg

It was a bureaucracy.

I'm also curious about the delay in going from O-1230, to the O-1430, to the I-1430 even despite the fact that the NACA cowling was created in 1929, and began to equip aircraft from 1932 on, and the design began in 1932: I'm curious how much multi-disciplanary skill did engine designers have with the rest of the airframe integration? For example did the guys designing the engines understand development changes in radiator and cowling designs?

I'm sure you realise that the late 1920s was a tough time for the aviation industry?

As far as I am aware, airframe integration was the job of the airframe manufacturer.

And if they weren't selling new products, they wouldn't be using the latest technology.

As for starting with something smaller, they did 6 years of single cylinder development.

You mean along with the engine right?

No, 6 years on single cylinder development before they built a V-12.

It was a small diameter 7 cylinder radial with 6 rows.

So the RPM would be higher than a 3-row radial with 14 cylinders?

Difficult to have a 3 row radial with 14 cylinders.

RPM was dependent on allowable piston speed, which was related to stroke. The R-2160 had a short stroke so could rev higher.

7 layshafts driving the reduction gear

That's to change the RPM down to something remotely reasonable I would guess?

The lay shafts were to connect the 3 cranks to the reduction gear.

The reduction changed the speed to something suitable for the prop.

[KJ_Lesnick]

wuzak

~1937

Okay

As the X-4520 was designed from the outset as an X, and it was air cooled

Wait, I thought inlines were almost always liquid cooled unless they were single row?

The X3420 was to use existing V-1710 cylinder blocks and heads, and was thus stuck with the same cylinder spacing. To use side by side fork and blade connecting rods would have meant the connecting rods weren't strong enough or the crank wasn't strong enough or both.

So it needed something tougher...

I'm sure you realise that the late 1920s was a tough time for the aviation industry?

I'm well aware of that, but the British generally did better than us so I figure...

As far as I am aware, airframe integration was the job of the airframe manufacturer.

However one would realize if they were smart that the reason for having an engine buried in the wings is to reduce drag: The rest flows from there...

No, 6 years on single cylinder development before they built a V-12.

Okay, I understand what you meant 

Difficult to have a 3 row radial with 14 cylinders.

Well, that's if it's air-cooled...

RPM was dependent on allowable piston speed, which was related to stroke. The R-2160 had a short stroke so could rev higher.

That I grasped, I figured everything else revolved around the need to lower the RPM to something the propeller could use

[wuzak]

Difficult to have a 3 row radial with 14 cylinders.

Well, that's if it's air-cooled...

So you would have rows of 5-5-4, or 5-4-5, or maybe even something really different, 6-2-6?

[wuzak]

As the X-4520 was designed from the outset as an X, and it was air cooled

Wait, I thought inlines were almost always liquid cooled unless they were single row?

Ever heard of the De Havilland Gipsy series of engines? Up to and including the Gipsy Twelve/King that powered the DH 91 Albatross?

Napier Rapier and Dagger?

Rolls-Royce Exe and Pennine?

Hirth inverted 4s and V8s?

Allison's air-cooled version of the Liberty L-12, the VG-1410?

The Ranger V-770?

The X3420 was to use existing V-1710 cylinder blocks and heads, and was thus stuck with the same cylinder spacing. To use side by side fork and blade connecting rods would have meant the connecting rods weren't strong enough or the crank wasn't strong enough or both.

So it needed something tougher...

No, the space wasn't there to do side by side fork and blade rods, so a master and slave rod would be required.

[KJ_Lesnick]

wuzak

So you would have rows of 5-5-4, or 5-4-5, or maybe even something really different, 6-2-6?

Uh, I thought you meant 14 on each-row!  Like 14, 28, 42...

Ever heard of the De Havilland Gipsy series of engines? Up to and including the Gipsy Twelve/King that powered the DH 91 Albatross?

I've heard of the engine, but knew nothing about specifics...

Napier Rapier and Dagger?

Rolls-Royce Exe and Pennine?

Hirth inverted 4s and V8s?

Nope

Allison's air-cooled version of the Liberty L-12, the VG-1410?

I know of the Liberty, but I didn't know they made an air-cooled version

The Ranger V-770?

Nope

No, the space wasn't there to do side by side fork and blade rods, so a master and slave rod would be required.

Okay.  By the way what took so long from 1937 to 1943 to get the V-3420 online?  I know the V-1710 crawled along at a snail's pace from 1929 to 1936-7 because of the depression and the NACA cowling