US Army Hyper Engine

[Shortround6]

The NACA cowl was being tested in 1928/29, By 1932 it was on quite a few aircraft but like many new things it took quite while to be fully adopted. While the difference between an uncowled engine and an NACA cowl is very large the difference between a townsend ring and the NACA cowl is not so marked. It was more expensive and made maintenance more difficult.

You need some way to adjust the amount of cooling the engine gets once you get much beyond needed 75% or more power just to stay in the air.
Once planes became streamlined enough to cruise at 60-66% power (or 70%) then you were either over cooling the engine or wasting power due to excessive air going through the cowling.

When climbing you don't have anywhere near the airflow through the cowling that you do when leveled off and cruising at high speed, let alone trying for top level speed.

It took almost 7 years to go from the first crude NACA cowling (no matter how great an advance that was) to the basic full featured cowling and there were more refinements coming but those were internal.

 

[Zipper730]

Continental did not want to spend Continental money on building the engine.

I thought the construction of the engine was paid for by the government? I remember in WWII there were entire factories that were totally owned by the government...

 

[Shortround6]

There was a vast difference it what the government would spend during the 1930s and what it would spend in 1940.

Please remember that even the Allison V-1710 was a very close run race between being adopted and being shut down.

IN the Spring of 1939 the US Army owed Allison over $900,000 dollars for work already done. General Motors, which owned Allison had already given Allison over 1/2 million dollars and was getting ready to pull the plug and shut down the V-1710 program (Allison was highly profitable in several other areas like bearings) The order of over 500 P-40s and over 700 Allisons in April of 1939 are what saved the Allison program.

Allison never got the $900,000 dollars. They had to "forgive" the debt to get permission to export (sell) the V-1710 to the French and the British.

Depending on government contracts was NOT a good way to make money during the 30s (1939 excepted). It may have been a way to keep to the doors open while waiting for better times.

If the army contracted for a single cylinder test engine to perform (complete) certain tests, that is what they paid for, a complete test. Even though they designed it should anything happen during the test (like a broken connecting rod) it was up to Continental to build the replacement part/s, rebuild the engine, and re-run any part of the tests not checked off as completed before the part/s broke before the Army would pay any money.
Continental, on their part, would not move on to the next phase (either building or testing any new parts/design) until the army did cough up the money for work successfully completed.

 

[Zipper730]

There was a vast difference it what the government would spend during the 1930s and what it would spend in 1940.

I didn't factor that in...

If the army contracted for a single cylinder test engine to perform (complete) certain tests, that is what they paid for, a complete test. Even though they designed it should anything happen during the test (like a broken connecting rod) it was up to Continental to build the replacement part/s, rebuild the engine, and re-run any part of the tests not checked off as completed before the part/s broke before the Army would pay any money.

How much money was spent to design the engine and how much was spent to build it? Because as I understand it as it was run the Army designed the engine and Continental built it...

 

[Shortround6]

How much money was spent to design the engine and how much was spent to build it? Because as I understand it as it was run the Army designed the engine and Continental built it...

Tracking down design cost would be difficult as the design work was done by either serving officers or civilian workers at Wright field who may or may not have been working on other projects at this time. Or who started there and left. How much time they spent in a given year on the Hyper project in addition to other duties would be a bit hard to work out.
Contract costs to Continental would be easier to find.

With the hyper project there were three things going on,
1 was the state of fuel development at any given time, fuel changed considerably during the course of the project.
2 was the engine design itself, what Displacement/rpm and other features were needed to reach the desired power goals.
3 was the state of materials/manufacturing. Even if the desired power could be reached could the engine survive more than a few minutes/hours at those power levels.

In regards to the last the first few hundred Allison R-1710s had to be sent back to the factory and reworked to bring them up to the design/contract levels of power. Until reworked they were limited to 2770rpm instead of 3000rpm and to around 930hp instead of 1040hp.

high performance engine design was not easy. Please note that the high power aircraft engines of the late 30s weighed less per HP than F1 racing car or Indy racing car engines.

 

[Zipper730]

Tracking down design cost would be difficult as the design work was done by either serving officers or civilian workers at Wright field who may or may not have been working on other projects at this time.

I'm mostly interested in what cost more: Coming up with the design or building the design?

Please note that the high power aircraft engines of the late 30s weighed less per HP than F1 racing car or Indy racing car engines.

I never would have thought that

 

[Shortround6]

I never would have thought that

Just to eliminate confusion that would be for the racing car engines of the time, not now

ANd the aircraft engines, despite their lower hp to weight ratio had to be much more reliable/longer laster.

Trying for 1hp per cubic in and doing it using commonly available gasoline and getting the engine to last for several hundred hours, even at a reduced rating was a very large challenge.

Please note that when Howard Hughes set the world speed record in 1935 for a land plane (he was still slower than the Floatplanes) he used 100 octane fuel that was being produced in such small batches that it cost over 10 times as much as "regular" av-gas (the floatplane racers didn't run on gasoline). People knew 100 octane was coming, they didn't know when.

 

[Zipper730]

Trying for 1hp per cubic in and doing it using commonly available gasoline and getting the engine to last for several hundred hours, even at a reduced rating was a very large challenge.

Wasn't the design equipped with two stages of turbocharging?

 

[Shortround6]

Just About all versions used an engine driven supercharger and a turbo-charger. Much like a P-38 or B-17/B-24.

Some of the last claimed power number for the -25 version are 1600hp for take-off at 3300rpm using 15.5lbs of boost (61in) and 2100hp (emergency) at up to 25,000ft at 3400rpm and 29lbs of boost (88in) the last needing 100/150 fuel.

Nobody has any record of it actually achieving that in flight, in fact getting to 1600hp in flight seemed rather problematic.

This is for the IV-1430, what they were planning for the earlier versions (the flat ones) I don't know.

 

[Zipper730]

Still, if you were to guesstimate: Which would cost more, designing or building? I'd figure building would be way more expensive...

 

[Shortround6]

Again, it depends on your accounting. If you engineering staff (officers and civilians) at Wright Field are being paid anyway, regardless of which project/s they are working on, dabbling with the Hyper engine may not cost that much out of pocket, or is hidden among other projects.

Please note they did not assemble a 12 cylinder version of the engine until 1939. all the "test" engines up until then were one or two cylinder engines. There were probably very few people, if any, who were assigned to the hyper engine full time. At least during most of the 30s.

 

[wuzak]

Still, if you were to guesstimate: Which would cost more, designing or building? I'd figure building would be way more expensive...

Building a prototype would be quite expensive. Possibly more expensive than the design.

But building production engines is much cheaper.

 

[Zipper730]

If you engineering staff (officers and civilians) at Wright Field are being paid anyway, regardless of which project/s they are working on, dabbling with the Hyper engine may not cost that much out of pocket, or is hidden among other projects.

Good point

Please note they did not assemble a 12 cylinder version of the engine until 1939. all the "test" engines up until then were one or two cylinder engines.

Why didn't they just go from 2-cylinder tests, to 4-6 cylinder tests, and from there to 6-12 cylinder prototypes?

 

[Zipper730]

Building a prototype would be quite expensive. Possibly more expensive than the design.

And the hyper was a prototype...

But building production engines is much cheaper.

Why didn't they sweeten the pot by proposing a production contract?

 

[Shortround6]

Good point
Why didn't they just go from 2-cylinder tests, to 4-6 cylinder tests, and from there to 6-12 cylinder prototypes?

A two cylinder test rig is one crank throw. Playing around with 2-3-4 crank throw engines actually doesn't tell you a lot about how the crankshaft and crankcase are going to act as each configuration has a different firing pattern and a different vibration pattern. The two cylinder test rig told you how the combustion was going work in the cylinder, they told you about the valves and valve train. they told you about the pistons, piston rings and connecting rods. Bite the bullet and build a 12 cylinder engine, the 1/2 way engines are waste of time and money. If they had paid for a complete engine they might have figured out out using a seperate cylinder engine was NOT the way to go much sooner.

Why didn't they sweeten the pot by proposing a production contract?

two problems
1 there was no money. Allison delivered 7 engine in 1937 and 12 in 1938, that is not even "production" in normal terms.
2. what were they proposing to build? Flat q2, V-12, inverted V-12? Until you have a complete engine go through a type test there is little sense proposing production contracts as you don't know what might have to be changed as a result of the test. The Army was probably dangling the idea of a production contract but nobody knew in what year it would come to pass and that is a lousy way to run a business.

 

[Zipper730]

The two cylinder test rig told you how the combustion was going work in the cylinder, they told you about the valves and valve train. they told you about the pistons, piston rings and connecting rods.

So, the idea was to see if the engine could make the specified horsepower? How many different prototypes did they build before they bit the bullet?

If they had paid for a complete engine they might have figured out out using a seperate cylinder engine was NOT the way to go much sooner.

If I recall they did that because they didn't think the strength could be taken otherwise...

two problems
1 there was no money. Allison delivered 7 engine in 1937 and 12 in 1938, that is not even "production" in normal terms.
2. what were they proposing to build? Flat q2, V-12, inverted V-12? Until you have a complete engine go through a type test there is little sense proposing production contracts as you don't know what might have to be changed as a result of the test. The Army was probably dangling the idea of a production contract but nobody knew in what year it would come to pass and that is a lousy way to run a business.

So the problem was financial issues and also the fact that they kept making engine design changes?

How should they have ran things?

 

[Shortround6]

So, the idea was to see if the engine could make the specified horsepower? How many different prototypes did they build before they bit the bullet?
If I recall they did that because they didn't think the strength could be taken otherwise...

Most engine histories don't spend much time on the hyper engine so any real numbers would have to come from government archives. Since this was also a shoestring operation the would sometimes rebuild a test engine using only such new parts as they were interested in testing. One "engine" may have been rebuilt several times.
This was actually fairly common, P&W built one test rig for the R-2800 as a 9 cylinder engine and used the nose case and gears from an R-1830 engine.
This is one reason there are so few prototype engines in museums. Nobody saw their worth at the time and they were either run to destruction and scrapped or modified/used in other programs/tests.

Please remember that Continental only built 23 actual 12 cylinder engines over a number of years before the program ended.

Enbloc engines are actually stronger than separate cylinders. They are also shorter (less room needed between cylinders) which makes for shorter, stronger crankshafts. RR stopped making separate cylinder engines with Kestrel, Curtiss never did and that was in the 20s. Hispanos were enbloc engines from the WW I V-8s. In fact the only people making separate cylinder engines by the beginning of WW II were the Italians.

 

[swampyankee]

Good point
Why didn't they just go from 2-cylinder tests, to 4-6 cylinder tests, and from there to 6-12 cylinder prototypes?

One and two cylinder engines are for checking and optimizing issues like combustion behavior and valve timing, which assume minimal interaction between cylinders. Two cylinder engines probably look at the behavior of the connecting rods and bearings in a pair of cylinders. The next prototype would be a complete engine, as accurately predicting things like intake behavior was beyond the era's technology.

 

[wuzak]

To get a sense of the slowness of development of the IV-1430, the Rolls-Royce PV-12/Merlin was started after the hyper program began, and was in series production and service when the first Continental V12 engine was run.


It depends on what type of engine was being designed as to what sort of test engine was required.

For the IV-1430 a single cylinder should have sufficed. Not sure if they did multi-cylinder development at all.

Obviously for the R-2800 the dynamics of the master and slave rods was crucial, so they built a 9 cylinder.

Rolls-Royce built V-2 test engines for the Crecy. This was because of the sleeve drive mechanism, which ran off the crank as well.

Wright built a 14 cylinder 2 row radial test engine for the Tornado project. The engine was to be built from 3 of the modules for 42 cylinders.

 

[Zipper730]

Most engine histories don't spend much time on the hyper engine

Other than how it was screwed up mostly. Frankly, had they just stuck to a V-cylinder they would have saved themselves a lot of grief because at least they're using the same basic shape.

The RAF didn't see any need for a flat-engine buried in the wings (admittedly, they also failed to notice stuff like constant speed props) and did fine.

Since this was also a shoestring operation the would sometimes rebuild a test engine using only such new parts as they were interested in testing. One "engine" may have been rebuilt several times.

Makes sense, if I was building something in my garage I'd have done the same (admittedly my house doesn't have a garage, so...)

Enbloc engines are actually stronger than separate cylinders. They are also shorter (less room needed between cylinders) which makes for shorter, stronger crankshafts.

Interesting.