XP-65/F7F Development

[Zipper730]

Let me guess. The test mule was fed compressed air at room temperature and the mule wasn't driving the compressor?

The compressed air was to simulate flow off the supercharger?

The supercharger was a gem, though, at least in idea (several patents were issued to the Ford people) - a 2-stage turbo-supercharger. Ie. there was no gear-driven supercharger stage, thus leaving more power for the prop.

Fascinating idea...

There was only one engine called "HYPER" and that was the Continental I-1430.

I actually thought it applied to the O-1230/I-1430 and O-1230 as well...

It should be noted that, unlike the other liquid cooled engines, the I-1430 was actually designed by the army. Continental was a subcontractor hired to build and develop the engine.

Why would somebody do this? It seems quite counterproductive...

The I-1430 was based on the Army's "hyper" cylinder design.

This meant hemi head and 2 valves per cylinder.

The O-1230/H-2470 was developed based on the same architecture, as was the Chrysler IV-2220.

Actually, many of the people at Continental quit and went to Lycoming

 

[Jugman]

There was more to the hyper cylinder than the hemispherical combustion chamber. Only the O-1080/I-1430 actually used Heron's design. The hyper name only shows up in connection with the Continental engine in official correspondences and reports. None of the other engines ( such as the O-1230 or the R-2160) thought of today as hyper engines were ever called that. I don't know when this trend of calling all the high power experimental liquid-cooled engines hyper engines started, but it wasn't used during ww2.

 

[pbehn]

The compressed air was to simulate flow off the supercharger?

Yes, but that is the problem, any simulation has gas flowing at a temperature, pressure and flow rate with a level of fuel to air mixture. The whole problem at the time was getting superchargers or turbos to deliver that level of flow, pressure and temperature at the optimum level of mixture at altitude. This apart from a single cylinder on a test bed bears only a passing resemblance to twelve of them linked together under a close fitting cowl at 25,000 ft. with one lubrication and cooling system.

 

[Jugman]

Zipper how is it counterproductive? Wright field didn't have the engineering resources or manufacturing capacity to build an engine on there own. As a dedicated engine design and manufacturing company Continental had experience in doing this sort of deal for other companies.

 

[pbehn]

Zipper how is it counterproductive? Wright field didn't have the engineering resources or manufacturing capacity to build an engine on there own. As a dedicated engine design and manufacturing company Continental had experience in doing this sort of deal for other companies.

Once war is declared every institution involved in military equipment are subcontractors and or project managers for the only client which is the government. Any institution connected to the government can hire the experts required to design something and commission some other organisation to put it into action. .

 

[Shortround6]

There was more to the hyper cylinder than the hemispherical combustion chamber. Only the O-1080/I-1430 actually used Heron's design. The hyper name only shows up in connection with the Continental engine in official correspondences and reports. None of the other engines ( such as the O-1230 or the R-2160) thought of today as hyper engines were ever called that. I don't know when this trend of calling all the high power experimental liquid-cooled engines hyper engines started, but it wasn't used during ww2.

Heron may have been gone by the time Continental was brought into the act.

Heron had designed an air cooled cylinder to be used on top of a Liberty crankcase and crankshaft. (or underneath, Allison made a small run of inverted air-cooled Liberty engines) but the smaller bore dropped displacement from 1650 to 1410 cubic inches. 5in reduced to 4 5/8ths.

Early attempts to prove Riccardo wrong and the need for sleeve valves included building a water jacket around one of the cylinders from the air cooled Liberty and spraying water on the cylinder heads. The results were encouraging enough for the next step to be taken. A complete water jacket covering both cylinder walls and head. At this point they decided to shorten the stroke to allow for higher rpm. They selected a 5in stroke as this would give a displacement of 1008 cubic in (84 cu in per cylinder) for hyper cylinder #1. This was tested in 1933.In 1934 the Army had become worried that other engines of larger displacement might be more powerful than their engine and had Continental develop Hyper Cylinder #2 of 118.8 cu in inches or 1424 cu in for the complete engine. Stroke was kept the same but the bore went to 5.5 inches making this engine one of the few oversquare aircraft engines of the era.
Work on the Lycoming started in the Fall of 1932 and the single cylinder test rig was running in the spring of 1934 and was of 102.8 cubic inches (5.25 bore X 4.75 in stroke) another over square engine.
It was pretty much in direct competition to the Army/Continental engine while the Allison used larger displacement and less rpm as a path to power. 142.5 cu in cylinders.

 

[wuzak]

There was more to the hyper cylinder than the hemispherical combustion chamber. Only the O-1080/I-1430 actually used Heron's design.

Yes, it was an oversquare cylinder, with a bore:stroke ratio of 1.1, whereas most of the time, like the Merlin and V-170, where undersquare (stroke bigger than bore).

It was also designed to run with high coolant temperatures - 300°F/149°C, though this was revised back to 250°F/121°C as it was realised that the reductions in radiator size were offset by the increases in the oil cooler size.

The hyper name only shows up in connection with the Continental engine in official correspondences and reports. None of the other engines ( such as the O-1230 or the R-2160) thought of today as hyper engines were ever called that. I don't know when this trend of calling all the high power experimental liquid-cooled engines hyper engines started, but it wasn't used during ww2.

That may be the case, but the O-1230, H-2470 and IV-2220 shared some general characteristics with the Hyper Cylinder.

Others, such as the R-2160, had less in common. And the Pratt & Whitney H-24 sleeve valve engines had nothing in common.

 

[Zipper730]

There was more to the hyper cylinder than the hemispherical combustion chamber. Only the O-1080/I-1430 actually used Heron's design. The hyper name only shows up in connection with the Continental engine in official correspondences and reports. None of the other engines ( such as the O-1230 or the R-2160) thought of today as hyper engines were ever called that.

Now that's interesting...

Zipper how is it counterproductive? Wright field didn't have the engineering resources or manufacturing capacity to build an engine on there own. As a dedicated engine design and manufacturing company Continental had experience in doing this sort of deal for other companies.

That's not what I meant: I found it strange that Continental pretty much had the army draw up the blueprints, and they build it. Generally, one tells the manufacturer what they want, and occasionally stipulate certain things; then the contractor builds it and updates the buyer...

Yes, but that is the problem, any simulation has gas flowing at a temperature, pressure and flow rate with a level of fuel to air mixture. The whole problem at the time was getting superchargers or turbos to deliver that level of flow, pressure and temperature at the optimum level of mixture at altitude. This apart from a single cylinder on a test bed bears only a passing resemblance to twelve of them linked together under a close fitting cowl at 25,000 ft. with one lubrication and cooling system.

Couldn't you test the engine on a mountain? The US has some that go over 10,000

 

[Shortround6]

That's not what I meant: I found it strange that Continental pretty much had the army draw up the blueprints, and they build it. Generally, one tells the manufacturer what they want, and occasionally stipulate certain things; then the contractor builds it and updates the buyer...

The "Hyper Cylinder" got it's start in the experimental area of Wright Field. Sam Heron was working for them at the time. He left at some point in the Early 30s and by 1934 he held the position of Director of Aeronautical Research at the Ethyl Corporation (makers of the Tetraethyl Lead used in fuel).
But Wright Field didn't have the resources (casting/foundry equipment, large machine tools, etc) for engine fabrication.
Unfortunately the Army was reluctant to give up their baby and in fact kept it on life support way too long. It wasn't canceled until 1944 or 45?

Couldn't you test the engine on a mountain? The US has some that go over 10,000

You could but why?
Dr Sanford Moss did test a turbo charger on Pike's Peak in 1918

But by 1940 most large aircraft engine manufacturers had test houses where they could control the atmosphere in terms of pressure/density and temperature to simulate high altitude flying. They could also pipe in pressurized air to test the basic engine (power section) and not be limited by supercharger development at certain stages in the program.

 

[XBe02Drvr]

Couldn't you test the engine on a mountain? The US has some that go over 10,000

Get real, Zipper! Do you have any idea what an engine test cell entails? Or the difficulties and expense of building on a 10K+ mountaintop where there aren't any roads and the terrain is too steep for conventional construction equipment and it's the middle of a depression and an isolationist mentality nation isn't even convinced the need is there?? How about a couple of Sikorsky Skycranes? Piece of cake, right? GET REAL!!
I suggest you read up about the project of building a weather station on top of Mt. Washington in NH. And tatt was only a 6K mountain. And that was considered a national priority at the time.
And what relevance does a 10K test cell have to an engine whose target performance arena is 20-30K?
Cheers,
Wes

 

[Jugman]

Continental didn't have the army do anything -well Continental did have the army draw-up a signed contract for every expense made by Continental- the Army came up with the basic design and needed someone to make it.

Prewar there was no such thing as a "pay-as-you-go" R&D contract. IF you had a contract with the services you had to deliver a discrete thing to them and it had to pass all contractual requirements. Then and only then would the funds be authorized and if those funds aren't there, you may or may not actually get paid in the end. GM/Allison didn't break even on the V-1710 until around 1942. That's twelve years into the project with sales much higher than one could have expected prewar.

With this in mind, I think, at least initially, the O-1430 was meant as nothing more than an experiment. There is no easy way to do this under the system that was in place at the time. By doing much of the design in-house, the army could get exactly what they wanted cheeper and faster. Well in theory they could. This obviously didn't happen and the hyper engine had one of the most, if not the most, protracted development cycles
of any engine of the era.

 

[Shortround6]

Add ended up as junk.

The amount of strength needed in the crankshaft/crankcase may have been severely underestimated in a number of engines as power grew due to boost or increase rpm. The separate cylinder construction became a bigger liability as engine power went up.

 

[Zipper730]

Get real, Zipper! Do you have any idea what an engine test cell entails? Or the difficulties and expense of building on a 10K+ mountaintop where there aren't any roads and the terrain is too steep for conventional construction equipment and it's the middle of a depression and an isolationist mentality nation isn't even convinced the need is there??

I'd almost swear there was a case where an engine of some sort was run on a mountain...

Continental didn't have the army do anything -well Continental did have the army draw-up a signed contract for every expense made by Continental- the Army came up with the basic design and needed someone to make it.

Prewar there was no such thing as a "pay-as-you-go" R&D contract.

When did that start?

With this in mind, I think, at least initially, the O-1430 was meant as nothing more than an experiment. There is no easy way to do this under the system that was in place at the time.

What about NACA? They were equipped for experiments...

 

[pbehn]

I'd almost swear there was a case where an engine of some sort was run on a mountain...

When did that start?
What about NACA? They were equipped for experiments...

Yes Zipper, but that is not true science. You can run an engine at 10,000 ft up a mountain but what does that tell you? You need it to be in its air frame with its cooling system, breathing system etc. You need to build a wind tunnel that supplies air to completely simulate conditions at 10,000 ft, but at the time there were no real problems at that level, you cannot build facilities at 20-25,000 ft because people die there and it costs a fortune. The solution is more research and more science, Aeroplane and its engine technology moved at a lightening pace between 1910 and 1940, from airplanes being designed in back rooms and built in garages to having all the worlds government throwing money at all its issues. NACA aerofoil profiles were not a private venture.

The trick is to find out what you can discover from a test like a single cylinder prototype and what you cant.

Stanley Hooker who made big strides in the development of supercharger for Rolls Royce also has this in his Wikipedia page,

"One major outcome of his work introduced a generalised method of predicting and comparing aircraft engine performance under flight conditions. The status of this work was summarised in an internal Rolls-Royce Report in March 1941 and made public by the Rolls-Royce Heritage Trust in 1997.[7]"

That is how science works, you find out what you know and what you can extrapolate from that and also what you cant. A single cylinder tells you some things about an engines performance but very little about how twelve or more linked together will do.

The P 51 was designed with the best aerodynamics known at the time, but after introduction its engine air inlet, its cooling air inlet and its tail were modified, that does not mean mistakes were made that means they did not know everything but did their best with what they knew.

 

[Shortround6]

I'd almost swear there was a case where an engine of some sort was run on a mountain...

See above posts.

Going on "location" helped in 1918 but you still have a truck load of variables.
Temperature on some of those mountains can change 20-30 degrees in just a few hours. Air density is not constant any more than it is constant at sea level. Dealing with rain or snow sure isn't going to speed things up either. In the high mountains it can snow in the summer. Doesn't stay but screws up any tests scheduled for that day. They had 15-22 years to develop climate controlled test labs right on the factory grounds after 1918 to help eliminate the variables and permit a test schedule that was more independent of the weather.
It made getting spare parts easier in case something broke.

Instead of us spoon feeding it to you;
Superchargers

 

[Jugman]

I don't know the exact date "pay-as-you-go" was initiated but I do know that the R-4360 the first engine project to use it. Also with this system all IP rights were transferred to the military. At least as far as manufacturing right were concerned.


NACA wasn't setup to do, nor was it their mission to do the kind of work the army needed.

SR6 I agree the use of completely separate cylinders was a bad idea . For poppet-valve engines the loss of a mono head and the rigidity it provides is much to pass up. For sleeve-valve engines I actually thing they're an improvement as you have all the disadvantages -and them some- anyways.

 

[pinsog]

Get real, Zipper! Do you have any idea what an engine test cell entails? Or the difficulties and expense of building on a 10K+ mountaintop where there aren't any roads and the terrain is too steep for conventional construction equipment and it's the middle of a depression and an isolationist mentality nation isn't even convinced the need is there?? How about a couple of Sikorsky Skycranes? Piece of cake, right? GET REAL!!
I suggest you read up about the project of building a weather station on top of Mt. Washington in NH. And tatt was only a 6K mountain. And that was considered a national priority at the time.
And what relevance does a 10K test cell have to an engine whose target performance arena is 20-30K?
Cheers,
Wes

Sir, I would imagine Zipper is a younger person that doesn't have the experience or knowledge of the rest of the group. Instead of berating him and talking down to him, try talking to him like he's your grandson. Obviously he is interested and would like to learn, so let's be kind and teach him, enjoy the opportunity to pass on your knowledge. Remember that none of us was born knowing anything, we all had to learn 1 step at a time.

 

[fubar57]

@pinsong read all the rest of his posts with multiple bloody quoting, quite frustrating and annoying. Plus he has been warned about it from the Mods on at least 2 occasions. Almost destroys the threads that I am interested in learning from. Much of what he asks can be found in less than a second using Google

 

[pinsog]

Fubar57, you certainly have a point and I have seen some that wouldn't or couldn't learn. I guess I just try to work pretty easy with anyone and everyone, that whole 'I talk to others like I want to be talked to' thing.

 

[XBe02Drvr]

Pinsog, your point is well taken, and I apologise. As Fubar says, we have a history with our Zipper, and sometimes go a little over the top in dealing with his questions. Thanks for calling me on it. I was out of line.
Cheers,
Wes