US Army Hyper Engine

[Zipper730]

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.

So the reason was for this had to with the economic climate, the unwillingness of the manufacturer to design an engine with their own money, and the constant design changes?

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

So they should have basically designed a single cylinder and then had the engine built around the cylinder specs?

 

[Shortround6]

For engines using two cylinders per crank throw (Vs, inverted Vs and some flat engines) a two cylinder test rig works well as you get to test the actual connecting rods and crank journal design.

Some aircooled engine makers used a common cylinder assembly for 4, 6, 8 and 12 cylinder engines. But they weren't trying to get anywhere near the same amount of power per cu in/liter as the supercharged hi performance engines.

 

[wuzak]

So the reason was for this had to with the economic climate, the unwillingness of the manufacturer to design an engine with their own money, and the constant design changes?

Continental were acting as the Army's jobbing shop.

They made what the army asked, when the Army asked, no more and no less.

 

[Zipper730]

Continental were acting as the Army's jobbing shop.

They made what the army asked, when the Army asked, no more and no less.

I get that, but I was under the impression that the reason this deal was hatched between the US Army and Continental (because you said so) was that they would not have agreed to designing the engine on their own money with US specifications outlined...

 

[Shortround6]

That is what happens when you get a government agency (the army) trying to radically challenge the accepted engineering standards of the day.
1 HP per cubic in (61hp per liter) was a goal exceeded by very few engines of the time of any type. Especially running on the gasoline of the day.
Any aircraft engine that had meet that standard was a short duration racing engine running on some sort of special brew. The number of car engines that could do it were also race engines running on semi-secret mixtures.
Things like a Delage 1.5 liter straight 8 Grand Prix engine running on 40% benzol, 40% petrol, 20% alcohol and a "zest" of ether for starting is hardly the basis for an aircraft engine.

The Army could have put out a specification but the number of bidders or companies responding would have been small and mostly of the crackpot variety.
The last Curtiss V-12 to built got 700hp from 1570 cubic inches.

 

[Zipper730]

The Army could have put out a specification but the number of bidders or companies responding would have been small and mostly of the crackpot variety.

I thought for national security matters, you don't have to select a competitor?

Looking back earlier in the thread, kmccutcheon wrote

In 1932 an agreement for the engineering and development of this cylinder and of the engine employing it was reached between the Army and the Continental Motor Company. . . . The company had earlier had an unimportant contract with the Army for a single-sleeve-valve liquid-cooled engine, which was dropped because of poor performance at the time the Hyper project was undertaken. . . . The Army not only had decided upon the basic principles and the size of the Hyper cylinder but also had laid down the main lines of the complete engine in which it was to be used, and the first two years of work were actually done in a special office set up by the company in Dayton to be near Wright Field.

I'm honestly wondering if the Army made the decision to just be building the engine manufacturer, like they wanted to be nationalizing engine production. Kind of like producing all the bullets...

 

[Shortround6]

The Army at the time had no money for building any manufacturing facilities. You are 3 years into the great depression. The Army was lucky it could order a few hundred planes a year (if that) let alone scheme to build engine factories.

The Army never schemed to make ALL the bullets. Their WW I experience taught them that the commercial sector could certainly provide large quantities of war material if necessary. The Army Arsenals avoided a monopoly and gave the army officers experience in actual costs of production (or production engineering experience) so they could evaluate contract proposals better.

 

[swampyankee]

The Departments of Navy and Army both maintained manufacturing and design facilities. One of the benefits of this was that both services had considerable in-house expertise, which has been lost since these facilities were largely closed.

 

[Zipper730]

The Departments of Navy and Army both maintained manufacturing and design facilities.

The Navy had it's own aircraft factory if I recall. I'm surprised the US Army didn't do that too.

One of the benefits of this was that both services had considerable in-house expertise, which has been lost since these facilities were largely closed.

That's a good point

 

[Zipper730]

I was thinking of two things: Wing thickness, and designs that actually did mount their engines in the wings.

I'm curious how thick they expected future aircraft wings to be? From what it seemed the decision to change the engine into a flat arrangement was around 1933 (AFAIK)

1. Martin B-10: Already flew (2/16/32); exact thickness is unclear, and I'm not sure if any data survives.
2. The Boeing XB-15/XBLR-1 & Martin XB-16/XBLR-2 weren't ordered until 1934 if I recall.
   • The XB-16 never flew
   • The XB-15's wings were so thick you could walk through them
3. Race Planes: By the 1931, it would appear a speed of 407 was achieved; by 1933: 423.6 was achieved. I'm curious if anybody paid attention to the thickness of the wings of these aircraft, or made any estimate of airframe thickness, combined with speed over time?

As for aircraft that mounted engines in their wings, I can't really think of any except one possible candidate: The Davis Manta. It never flew and had a number of problems in that it would likely never have produced anywhere near the speed on projected power, and with the wind-tunnel model "disappearing" at a highly convenient moment (investigations, possibly into fraud), it only seems to confirm my suspicion.

Regardless, the aircraft was half wing mounted, and half amidships mounted in that it was mounted amidships, and the wing was shoulder mounted and so thick the engine was effectively buried in the wing (the fuselage tapered into the wing, and extended out aft of it).

Was this design inspired by the Wrights proposals of stuffing the engines in the wings?

 

[Shortround6]

The XB-15's wings were so thick you could walk through them

Walk is a bit of an exaggeration. This a 314 Clipper wing but it was only 3 ft shorter than the XB-15 wing. I would also note that the 314 Clipper carried over 4000 gallons of fuel in the early models and over 5400 gallons in the late version. Not all was carried in the wing but thick wings made fuel storage easy for bombers.

Race Planes: By the 1931, it would appear a speed of 407 was achieved;

Notice the bracing struts. You can get away with a a thinner wing if you aren't depending on the the wing itself to handle all the bending loads,

How much of the struts/wires were to brace the pontoons and how much the network of struts and wires braced the wing I have no idea, somewhat of both?
Please note that the race planes were stressed to a much lower standard than fighter planes, NO 6G turns or pullouts for example.

Somebody may have known that thin wings had less drag. What was unknown was how much less drag (and at what speeds). This was complicated by the known fact that a thin wing of a given strength was heavier than a thick wing of of the same size and strength. Thin but heavy wing for more speed or thicker and lighter wing for better climb and maneuverability?
Please note the race plane used a 30 ft wing span and had 145 sq ft of wing area.

 

[Zipper730]

Walk is a bit of an exaggeration. This a 314 Clipper wing but it was only 3 ft shorter than the XB-15 wing.

Did that include the crawl space, or just the whole wing thickness?

Notice the bracing struts. You can get away with a a thinner wing if you aren't depending on the the wing itself to handle all the bending loads,

So there was an assumption that a non-racer would have thicker wings to support itself from within?

Somebody may have known that thin wings had less drag. What was unknown was how much less drag (and at what speeds). This was complicated by the known fact that a thin wing of a given strength was heavier than a thick wing of of the same size and strength.

It would appear that, at some point, they had concluded that a fighter could not carry an engine within its wings (at which point they went to an inverted-V), which makes me wonder how much thoughts they gave to this early on (the USAAC had some elements in it that were almost comically bomber-centric).

How tall was the O-1230? I ask because the Seversky P-35's wing was around 0.18:1 based on a drawing I have and that seems around 16-17 inches thick.

 

[Shortround6]

="Zipper730, post: 1479554, member: 67843"]Did that include the crawl space, or just the whole wing thickness?[/QUOTE]

3ft less wing span. I would imagine that much of the interior wing structure as the same or similar.

So there was an assumption that a non-racer would have thicker wings to support itself from within?

The racer had over 2200hp at sea level compared to the 880 om a Merlin II/III. They thought the struts/wires caused drag and a thicker wing without struts/wires would have less total drag.

How tall was the O-1230? I ask because the Seversky P-35's wing was around 0.18:1 based on a drawing I have and that seems around 16-17 inches thick.

It was never going to fit in a single engine/single seat fighter wing. The basic engine was fairly flat but the magnetos, intake manifold, supercharger and carb all added to the hight.

It might not have done too bad in something the size of an Airacuda though.

 

[wuzak]

="Zipper730, post: 1479554, member: 67843"]
It was never going to fit in a single engine/single seat fighter wing.

Why would anyone want to fit an engine for a single engine fighter in the wing?

In any case, I don't think it would have fitted inside the wing of a P-38 either.

 

[Shortround6]

It wouldn't. but then the engine/s were conceived at a time when such things as the Airacuda (684 sq ft wing) and A-18 Shrike ( 530 sq ft wing) were being worked on.

We are right on the edge of some military planes using flaps for landing let alone take off so wings were bigger than on later planes.

 

[Zipper730]

="Zipper730, post: 1479554, member: 67843"]3ft less wing span. I would imagine that much of the interior wing structure as the same or similar.

Oh, never mind...

It was never going to fit in a single engine/single seat fighter wing. The basic engine was fairly flat but the magnetos, intake manifold, supercharger and carb all added to the hight.

So it was a faulty premise even back then? I'm looking at the PB-2A/P-30 and I'm also getting T/C figures of 20%, but even then the aircraft's only 30 feet long, and with the chord being what it is -- almost 128 inches just outside the fillet, and with 20.2% from that area that gives me 25.8" thickness, which is substantial and might even be able to fit inside. But that's almost at the root.

Do you have exact dimensions for that engine?

It might not have done too bad in something the size of an Airacuda though.

True, but that plane was huge and was only stressed for 5.1 ultimate and 3.4 normal. That said, the Beaufighter TFX was not much smaller (in length anyway), and could pull 8.5G at 25120, about 8.9-something at 24000 and 9.5 or so at around 22450 (basically with the torpedo off).

There was that chart that listed aircraft components and g-load, and I based it on an 8.5g load at 25120 and that coming out to the ability to lift 213520 lbs.

Why would anyone want to fit an engine for a single engine fighter in the wing?

It was based around the idea of reducing drag. I'm not sure what they knew about radiator design and reducing cooling drag.

 

[wuzak]

It was based around the idea of reducing drag. I'm not sure what they knew about radiator design and reducing cooling drag.

Well duh.

Which wing do you put your single engine in for a single engine fighter?

 

[Zipper730]

Which wing do you put your single engine in for a single engine fighter?

Good point! From what I remember, they wanted the flat arrangement to reduce drag in bombers. Then they figured that the bombers wouldn't need more power than the engines would allow (I'm surprised they didn't just add more engines), and then figured -- hey we can use this on fighters -- wait we can't put this engine in a fighter wing.

I'm surprised they didn't just put a flat cylinder in the fighter's nose it'd probably allow a little bit of visibility to be improved, or something like that.

 

[swampyankee]

Well duh.

Which wing do you put your single engine in for a single engine fighter?

The top one?

 

[Shortround6]

I'm surprised they didn't just put a flat cylinder in the fighter's nose it'd probably allow a little bit of visibility to be improved, or something like that.

The engine was actually rather large. The one test bed aircraft went from this.
to this