Heliopters & autogiros for the ww2: underused, or not worth it?

[tomo pauk]

Some countries used helicopters and/or autogiros prior/during the ww2. Could it be worthwhile if they were built (better, more useful ones) in greater numbers, or that would represent a wasteful effort? I'm not just pointing into 'sexy' applications (CAS, tank busting etc) - primary missions including medvac, transport of different shapes & sizes, patrol, SAR etc.

[Shortround6]

You have bit of a timing problem. Helicopters are very sensitive to power to weight ratios. To make useful helicopters you need engines that are powerful for the their weight. helicopter engines (especially piston engine ones) tend to operate at either full throttle or a lot closer to it than fixed wing planes operate their engines. Helicopters don't spend much time at 60% power or less. Engines in Helicopters often had much lower time between overhauls than the equivalent engine in a fixed wing aircraft.
The timing problem comes from the fact that there were few suitable medium power engines available. Most engines in the 400-800hp range were "left-overs". older versions of engines that didn't have the most up to date power to weight ratio. SO you have a choice of trying to use a small engine in a small helicopter with the resulting small useful load, a "medium" engine in a medium helicopter that may offer double or triple the payload/range of the light helicopter, which isn't saying much because the light helicopters don't offer much more payload/range than a Piper Cub, or raking a real gamble and trying for a high powered Helicopter with 1200-2000hp. The Trouble in WW II is that you only have a couple months time to play with the light/small helicopter prototype before you have to start cutting metal on the high power one if you are going to get a production version in service in WW II. If everything doesn't go strictly according to plan the whole thing is a waste of effort as far as WW II goes. Major benefits post war though.

More might have been done with both helos and auto-gyros than was done but they probably weren't going to be game changers.

[davebender]

Fi-256 are good for artillery observation but helicopters are better. That's why we still use them today (supplemented by UAVs). I suspect the ~800kg Fi-285 would have been dirt cheap to mass produce. The Heer missed the boat by not embrasing this observation helicopter during 1942.

[davparlr]

Interesting topic, I think that autogyros had very limited applications, except maybe artillery spotting, so I won’t address them. Helicopters are a different story. Both America and Germany had useful helicopter designs that, by mid-late war were mature enough to support military operations. The problem with German helicopter usage was that the early helicopters had little war fighting capability do to limited weapons carrying ability and slow speed. And since Germany was starting to be pressed hard at the time helicopters started to mature, the question seems to be would it have been wise to divert resources into an innovative but little understood and the seemly limit fighting ability of this aircraft. I would guess, no. America, on the other hand, was not under such constraints yet helicopter usage was limited. They had the Sikorsky R-4 and the very capable R-5, which contributed much in the Korean War. I suspect that both the Germans and the Americans did not fully understand the potential of what they had nor understand the infrastructure necessary to achieve that potential. The helicopter would have been very useful in the Pacific in medevacs and light materiel support and on board carriers, as it was later successfully used. This all changed over the next fifteen years.

So, I guess my answer is no for Germany, but yes, underused and would have been worth it, for the Allies.

[davparlr]

The Heer missed the boat by not embrasing this observation helicopter during 1942.

I suspect this was a pretty universal attitude toward this new toy.

[gumbyk]

Sikorsky produced the R-4, R-5, and R-6 helicopters during the war, mostly used for rescue.
Sikorsky tended to use radial engines, for the better power to weight ratio that they could provide.

I think that, with hindsight, they were under-utilised, much the same way you could say that the aircraft was under-utilised during the early stages of WW1. I agree with Dave, no-one fully foresaw the usefulness of the helicopter, but had the war extended another couple of years, we may have seen more rapid acceptance of the helicopter.

[muscogeemike]

I read once that Japan used autogyros from a ship against sub’s in WWII.

[norab]

actually the Japanese did field autogyros for artillary sotting and anti- submarine work. One may have sunk a US sub,



Kayaba "Ka"-Go / Ka-1 helicopter - development history, photos, technical data

I think the biggest problems with Helicopters and autogyros at the time was a general ignorance of their peculiar and unusual abilities

[davebender]

Like V2 rockets and Type XXI submarines? Those innovative but unproven and little understood programs were given a blank check.

The Fi-282 observation helicopter was tested and approved for production during 1942. Why not give Anton Flettner 5% of the V2 budget for helicopter production? Unlike the V2 and Type XXI submarine Flettner helicopters would be contributing to the German war effort during 1943.

[Shortround6]

Their capabilities were rapidly evolving, as were supporting technologies. For instance the R-4 used a 200hp engine and had a useful load of 483lbs for crew, fuel, oil armament and depending on definition of empty weight, radios. The later R-6 used a similar sized rotor (if not the same one?) but a more powerful engine (240hp), better streamlining and other improvements increased speed from 75-82 mph to 100mph. Gross weight only went up 19lbs though, I don't have the empty weight to figure out the useful load but it can't be much different. For these small helicopters every pound was important, many of their performance specifications are suspect as they come from trading one attribute for another. Max range or endurance is often achieved with auxiliary fuel tanks that take the place of the second crew man or any other useful load. While they may carry two stretchers it is not only without a second crewman but it is with less than full standard fuel tanks.

TO be a useful artillery spotter required a second crewman and a decent radio set up. A new model radio that was 20lbs lighter than a previous model could mean 3 to 3 1/2 gallons more fuel and on some of these early low powered helicopters that could be around 10% of their fuel load.

Please note that a Piper L-4 Grasshopper with a 65hp engine had a useful load of 455lbs and a top speed of 85-87mph and an endurance of about 3 hours on about 12 gallons of fuel.

More could have been done with both types but please try to work out what size machine would be needed to actually perform a useful job like anti-sub patrol. two men, radio, even a pair of 100lb bombs to make at least some sort of attack (no sub even wants to be damaged deep in enemy waters) and enough fuel for, say a 2 hour patrol? if you want an aircraft in the sky at all times during daylight the relieving aircraft has to take-off before the relieved aircraft lands. You don't want worn out crews but one hour patrols spend too much time taking off and landing. You need a useful load of at least 800-900lbs if not more and that starts to put you into the 450-600hp class of aircraft.

[gumbyk]

Sikorsky R-5 (from wikipedia, so who knows how accurate it is!) Gives some idea of the performance.
General characteristics
Crew: 2
Capacity: 2 stretchers in external panniers
Length: 57 ft 1 in (17.40 m)
Rotor diameter: 48 ft 0 in (14.63 m)
Height: 13 ft 0 in (3.96 m)
Disc area: 1,810 sq ft (168.2 m²)
Empty weight: 3,780 lb (1,718 kg)
Loaded weight: 4,825 lb (2,193 kg)
Powerplant: 1 × Pratt & Whitney R-985, 450 hp (335 kW)

Performance
Maximum speed: 92 knots (106 mph, 171 km/h)
Range: 313 nmi (360 mi, 580 km)
Service ceiling: 14,400 ft (4,390 m)

Climb to 10,000 ft (3,050 m): 15 min

So, for 450HP you would basically get a two-place observation platform. There were plenty of fixed-wing aircraft that could do that, and they would have been a more stable platform too.

So, a useful load of 1045 lb.
pilot and gear, 200 lb
co-pilot and gear, 200 lb
pair of 100 lb bombs, 200 lb
fuel 445 lb (280 litres, 74 US Gal) I'm not too sure what fuel endurance was, but it looks like around 3 hours.
I haven't even thought about radios, etc. This would eat into the fuel available too.

This heli was available right at the end of the war, so I guess that any earlier there just wasn't a suitable aircraft available.

What more would a helicopter with these capabilities have achieved that wasn't adequately being covered by a fixed-wing aircraft?

[davebender]

Those characteristics aren't terribly important for an army division aviation detachment. However the ability to operate without an airfield is a huge advantage. Fi-282 / Fi-285 observation helicopters can operate from the same terrain as artillery battalions they are supporting.

[davparlr]

Like V2 rockets and Type XXI submarines? Those innovative but unproven and little understood programs were given a blank check.

It is strange to me to compare the helicopter to the V2 and the Type XXI sub. Both the V2 and sub were perceived as potential war winning weapons, certainly potent weapons. I don’t think anyone in any military thought that of the helicopter.

The Fi-282 observation helicopter was tested and approved for production during 1942.

I am familiar with this helicopter design. In the early ‘70s, we had its modern equivalent Kaman HH-43 Huskie stationed at our training base as emergency rescue helicopters. We called them Pedros due to their call sign. If there was any helicopter deserving to be called “egg beater” the Flettner design was it!

What more would a helicopter with these capabilities have achieved that wasn't adequately being covered by a fixed-wing aircraft?

Medevac. Unfortunately, at this time I do not think the military or medical experts recognized the importance of rapid medical attention that, with the help of helicopters, revolutionized battlefield survival rates. Korea really started the ground work for this very important support task of the helicopter.

While helicopter warfighter applications improved in the early 50s with the likes of the H-19 Chickasaw and H-34 Choctaw, and developing Air Calvary insertion and removal tactics, the real advance came with the gas turbine engine and the game changer HU-1 Iroquois (Huey).

[tomo pauk]

Could someone make capability estimates for a helicopter powered with, say, R-1820?

[Shortround6]

While helicopter warfighter applications improved in the early 50s with the likes of the H-19 Chickasaw and H-34 Choctaw, and developing Air Calvary insertion and removal tactics, the real advance came with the gas turbine engine and the game changer HU-1 Iroquois (Huey).

And that is a really big part of it. The engines in the early Hueys could give around 850-860hp and yet weighed about what a Lycoming flat 6 of around 240-280hp did. later versions gained power faster than they gained weight. Similarly the Allison shaft turbine in of 317-420hp in the Hughes and Bell light helicopters weighs less than a Lycoming O-235 of about 100hp. Small and medium Turbine powered helicopters of the 50s could have useful payloads 200-600lbs higher than a piston powered equivialent at the SAME gross weight. Almost as important was the fact that the turbines, with more advanced engine controls could be more easily "flat rated". Engines were held to below peak power in normal conditions at sea level so that they supplied a steady amount of power as the Helicopter climbed or in high/hot conditions.

This improved useful load and the "flat rated" engines which supplied a reserve of power added greatly to the the small-medium helicopters usefulness.

Also consider the Sikorsky S-55 and the Westland Whirlwind helicopter. As with all aircraft on on going search for more power lead from the 600hp R-1340 of about 800lbs to the Wright R-1300 seven cylinder engine of 700hp and over 1000lbs



to a 14 cylinder radial of 750hp and 1200lbs, the Alvis Leonides Major 755 and finally to the under 300lb but over 1000hp Gnome turbine (license built General Electric T-58 ).

All in the same airframe. The Piston engine versions could carry either dipping sonar or a SINGLE MK 44 torpedo (432lbs) but NOT both at the same time.

Please remember that most aircraft specifications are given at sea level and at 59 degrees F. Higher and hotter degrades both engine power ( for non-supercharged engines) and lift for both winged aircraft and for Helicopters (rotary wing). An 800lb useful load at sea level and 59 degrees could fade considerably at even 4-5000ft and 100 degrees.