What if helicopter development was accelerated in World War 2?

First post and a great one too (even if making a fool of myself )! Positive rep on the way

 

Shucks, thanks.
(I posted some comments in the Me262 supersonic thread too if you're interested and wrote large portions of the wikipedia V1 entry.)

Interestingly, the Kolibris had a lifting capacity for their weight and engine power unmatched by most modern helicopters. Rather than being a primitive configuration, the synchropter is a highly effective helicopter configuration with many advantages over conventional craft. However one obvious drawback of the Kolibri's small size was the non vertical angled rotor hubs resulted in the blade tips at the sides of the craft being around body height and made the craft dangerous to approach from the ground whilst the blades were spinning. They had a simple rule that ground crew could not approach at that time or only directly from the front. The Fa 223 had no such problem and could be loaded and unloaded whilst generating lift from the rotors.
The kolibri used to shake laterally on rotor start up as a result of some harmonics at low rotor speed and a modern derivative shares this trait. Once at operating speed everything smoothed out. A tiny drawback against many advantages.
The Kolibri's configuration is seen today in the spectacular Kaman Kmax which holds various lifting records for it's size. Pilots claim it is probably the easiest chopper to fly in the world and one of the most stable which is why it is used for much heavy lift utility work. The twin rotor system means it packs heavy lifting punch for a small rotor diameter.
The kolibri was highly regarded by its pilots. Watch the youtube vid and see the amazing stability and control of the Kolibri. One shot shows the pilot drifting his craft past the ship with both hands in the air! Yet despite the astounding stability it had aerobatic qualities that made it nearly impossible to shoot down by fighters. This came in handy when they were used for artillery spotting on the eastern front and came under attack from russian fighters.
The earlier Fl 265 had similar qualities and would have been effective in mass production too, demonstrating its ability to perform sea rescues, line lifting and towing of people, boats and land vehicles. Anton Flettner was a perfectionist though and sent the 5 Fl 265s into combat at sea whilst he developed the easier to manufacture and more versatile 282.
He obviously thought the 282 had more potential for observation with its forward pilot position and rear observer/gunner rumble seat.

 

One has to note that postwar, the only reason the US Army invested so much into helicopters was the Howze Board decision that relegated all armed fixed wing aircraft to the Air Force. This forced the Army to adopt the helicopter for most aviation missions.
A good example of this is the joint Army / Marine developed OV-1 Mohawk. This aircraft was fitted to take 8 wing hardpoints (4 each side) along with a fuselage hardpoint for ordinance and could be armed with up to four 20mm cannon internally. The Marines insisted on these options expecting to use this aircraft for close ground support.
The Air Force went absolutely ballistic over the Army getting this aircraft and wanting 24 per division. They saw it as a backdoor end run by the Army to get their own ground support aircraft. The Army was forced, literally forced, by Congress to accept only limited numbers of the OV-1 as an unarmed reconnissance airplane. This pretty much killed it for the Marines too. This is unfortunate as the OV-1 is and was probably a better close support aircraft than the Harrier.

Basically what I am pointing out is that fixed wing aircraft are actually better for many- the vast majority actually- of missions the Army has to carry out. Helicopters are quite limited and given the choice a poor second to aircraft. On the whole there are a few missions where they are necessary and relavant, but not many.

 

That is true. The reason I raised the idea in the first place is because of a post on Waco gliders. So it dawned on me that maybe, just maybe some form of helicopter could either replace or supplement the use of these gliders. It's not farfetched to have a helicopter in some form or other in operational wartime use had enough research and development funds were devoted to it. If such was so, it is plausible that it wouldn't be that inferior an aircraft to the standard fixed wings.

Let's take two campaigns and see how it could have played a role.
Normandy: (after Overlord) if a powerful enough helicopter was in existence, it could allow rapid movement of troops to bypass German strongpoints during hedgerow fighting, allowing for a faster campaign. Losses would be expected though.
North Atlantic: a chopper operating from a ship within a convoy could be used as a platform for helping spot U-boats. Certainly, it would be easier to operate rather than float planes, which needs a crane to get it back to its ship.

 

Very interesting post and some great reading.

Fundamentally, the helicopter has always had a problem in combat regardless of era or conflict. It is an incredibly vulnerable aircraft which can endure only light damage before being disabled.

It proved extremely valuable in Vietnam, to a lesser extent in Korea and has had its cameos in other conflicts, Gulf, Falklands, Afghanistan, Iraq etc. However, combat losses in attack and particularly transport roles in front-line duties have always been relatively high.

The crucial issue here though, I feel, is that when the helicopter has done well it has been when deployed in limited engagements where front lines are sporadic, fleeting and fluid and generally where helicopters were able to travel large distances over relatively safe territory before reaching "hotspots" of enemy activity, carrying out their mission, and getting out as quickly as possible.

In WWII the helicopter, no matter if it had been developed even to recent standards, would not have been afforded this luxury. The front line was generally stable. Flying over the front line would have encountered inevitable heavy engagement from ground forces and enemy aircraft.

One RAF pilot stationed in Germany during the Cold War explained that quite simply the role of the RAF helicopter force based in Germany in the event of a conventional Soviet invasion - a situation more akin to WW2 battles - was to try and drop off as many small artillery anti-tank units at key geographical bottlenecks to try and stall tank formations for as long as possible. The expected survival rate of the helicopters and crews after just days was extremely low.

Modern helicopters are now further protected by their stand off weapons systems. Apaches, Cobras etc can stay out of direct small arms fire by firing from distance. But these kind of weapons systems were probably in a less advanced state than helicopters towards the end of the war.


There would certainly have had a role, in logistics, insurgency and special forces - perhaps much like the RAF's SOE Lysanders which proved invaluable carrying agents into occupied Europe.

But as far as contributing to any large scale engagements, their role would almost certainly have been negligable, and the losses catastrophic, even if commanders had allowed them anywhere near the front. The first RAF Meteor jets were ready by June 1944 but were not deployed over Europe for fear of the technology falling into German hands. It would have been almost inevitable that any allied force would have used a similar strategy if helicopters had been developed. In the hands of Germany towards the end of the war, I'm sure like every other development they would have been thrown into haphazard operational use, and almost certainly wiped out within months.

Well that's my two bob's worth
Cheers!

 

Considering the Germans already had used jets, had axial flow turbines, afterburners, turbo props etc and were aware of centrifugal turbines I'm not sure it was the British jet technology itself they were worried the Germans would copy. Just fear that the Germans would know exactly at what stage of development the British were at.
The Germans already had spectacularly performing helicopters able to lift artillery and whole airframes. They were already being thrown into use, it wasn't hypothetical. They had already used helicopters for submarine spotting and dropping marker flares over the submarines.
They already used helicopters for picking up downed airmen, artillery spotting and other observation duties.

 

Very basically without going into all the points again, the helicopter could never had chamged the war, just the possible effects that it could have after the war, in terms of deployment and uses.

 

There's some stunning Footage of a Fa-223 airlifting a whole fieseler storch off the ground here. Image and Film Galleries And the remains of a FW190 and a kübelwagon.
Apparently the FW remains were flown over 30kms to a parts recovery area.
Also some nice footage of a Fl 282 being assembled from storage on the back of a ship at sea: Image and Film Galleries and being tested by Allies after capture: Image and Film Galleries

 

An interesting alternative possibility is the US XF5U "flying pancake." The original Zimmerman prototype proved to be a good flying machine on very limited horsepower. The production model was expected to hit 500+ mph (probably a highly optimistic figure) but even if it only did a bit over 400 it would still have made a powerful alternative to helicopters. The aircraft could take off using a very short run of just tens of yards and land nearly vertically.
A variant for use as a small transport with landing gear suited to rough fields might have been a viable alternative to the helicopter. Certainly, the higher flight speed, ability to fly over a larger range of altitiudes, the probability that it could actually defend itself against an enemy aircraft, and its longer range all argue that it would have made a good helicopter replacement.

Vought V-173 / XF5U-1 Flying Flapjack Info

 

Thanks Grommo I enjoyed lerning about this.

 

If this kind of wing worked so well, why did the concept vanish with the cancellation of this project? I would have thought that the skies would be full of nothing else...

 

Because the concept is limited to propeller driven aircraft. The props are an integral part of generating the necessary lift over the "wings" such as they are. The jet did away with the concept; although I also suspect that its limited development also simply relegated it history rather that wider acceptance.

 

Yes T.A., the pancake was a spectacular design . Testing of concept models showed tail-sitting hovering modes but the full size craft did not seem to have sufficient rotor lifting power for hover.
Footage of it landing at what almost appears to be running pace, (I'm exaggerating slightly) shows it possible suitability for ship board use and landing on rough and remote tiny island airstrips.
Watching the doco "strange planes" seems to suggest that due the requirement for greater power to match other fighters speed, the drive-train complexity escalated and the weight penalty offset the performance gain.


The british alternative to island combat fighter support was the Saunders Roe jet seaplane where you could have jet speed and still land almost anywhere in the lee of an island.

 

The prototype test bed flew on just 160 hp and weighed about 2200 lbs loaded for a power to weight ratio of .082.

The intended production version had 3200 hp on 15,000 lbs load or a ratio of .213. That's alot better than many other fighter aircraft of the period had by quite a margin. But, since it never flew any real test flights we shall never know for sure.

Seaplanes, jet or prop, have some severe drawbacks. The biggest is the need for a planing hull and having the engines mounted such that they will not ingest water or spray. These problems along with the saltwater corrosion issue make them less than desirable in many applications.
The Zimmerman design built with a couple of turboprops of even greater power could even today provide a useful ground attack design. I would think that the aircraft itself could be made rather stealthy without undue difficulty and having the engines buried on the top of the "pancake" would make them less vulnerable to dust and fod ingestion while the exhaust in such a location would reduce the IR signature to ground fired missiles.

 

i'm more interested in hovercraft development, both with submerged propellers and pure hovercrafts. would the germans having those have made sea lion feasible?

 

I suggest you check out wiki as an introduction to the history of the hovercraft's development. Hovercraft - Wikipedia, the free encyclopedia

Another one would be Hovercraft history.

The website MilParade.ru | #32 | Levkov s Hovercraft has an article on Soviet research on the hovercraft's military applications. I concede that it was the Austrian Hungarian navy that first looked at some form of hovercraft in the pre-WWI era but they didn't continue it. The Soviets in the 1930s made an effort and did produce some craft. However with Germany rampaging across the countryside, the development was still born.
It's unlikely, though, for the Germans to have developed hovercraft for crossing the Channel to invade England. Even if German pilots did prove the existence of the ground cushion effect with the Dornier aircraft, as far as I have checked, the German research didn't dwell into hovercraft.
The modern-day British inventor recognized for the development of today's hovercraft is lucky that the Soviets had such a penchant for secrecy.

 

The German Navy had a standing requirment for improved naval aviation due to ToV preventing them having carriers. Back in WW-I they resorted to sticking Small sea planes on the fantails of their Destroyers to improve naval aviation.

Torpedobootzerstörer History

Großes Torpedoboot 1913 History

Through the 1930s Admiral Raeder kept an eye on developments like the C-30 autogyro [They aquired 40 in the mid 1930s that were scraped by WW-II but 15 were captured from France in 1940] and the fledgling Fl 184 & Fl 185 helicopters...which lead to the Fl-265 experimented in early 1940s on warships and then the Fl-282 which was used on convoy patrols late in the war. However Hitler always argued before the war, that the German warfleet would not be needed until mid 1940s, so little funding and development occured.

If that is all changed, its not hard to see some of these helicopters on warships as small as TB from 1940 on. Mindyou they would have to loses a Torpedo rack or 4" gun to make space for such helicopter. In fact some Fl-282 were trailed operating from tiny UJ vessels. For Crusiers and larger a helicopter could operate from each upper turret roof , maybe a couple on battleship turrets?

In naval warfare finding the enemy is most of the battle. So the more airborn searching platforms the better. The Fl-282 proved to be very good at spotting subs approaching to periscope depth [as much as 150 feet below the surface] .

Then ofcourse their was the numerous converta plane concepts <evil grin>. Actually the Fl 269 could have been made to work with the limited rotar swivel as a STOL. I gather that late in the War the Germans trailed Fi 156 storch on cruisers like the Hipper. they could get the plane to slow down to ~30mph to match the Hippers speed , but could not get it to work in the wake of the turbulance from the superstructure? No idea where they would have landed it?

 

I don't think the helicopter would have done much in WW2, besides create a more advanced base from which postwar development would have been a step ahead.

Helicopters, even today, are very vulnerable to SAMs, ground AA, and enemy fighters. Extensive strategies have been put into place to help. In Vietnam, helicopters were widely used because the U.S. had basically achieved air superiority. Even so, piloting was a hazardous job, with the AA that dotted the Vietnamese country.

The only way, IMO, that helicopters would help in a full-blown war, with both sides roughly equal, would be their now super-range. If both belligerents were equally matched, the effectiveness of helicopters would take a nosedive. Imagine if Iraq in 1991 was good enough to keep their SAM defenses up and running, and get well-trained pilots in advanced interceptors up in the air? The usefulness in the helicopter is underscored by its massive firepower. Gunships can take out tanks from miles away, thanks to advanced missiles and electronic equipment. Without such a capability, helicopters in WW2 would essentially be ground attack planes, but without the air-to-air capabilities and without the speed and toughness of the fighters.

Otherwise, modern transport choppers are the equivalent of the truck in WW2, just that it is not as extensive. Imagine it as a superfast truck. That would be its only asset in WW2. As such, funding was not allocated to the research of rotor aircraft, because there was just no battlefield potential.

 

The germans did mock dog fights between fighters and helicopters and found that it was very difficult to get a helicopter in the gun sights long enough to have shot it down. Its almost impossible when the Helicopter is using NAPE tactics , which the Germans were experimenting with as well.

One way in which helicopters can make a big difference in addition to naval scouting and ASW , is 'economy of force' missions. A dedicated scout helicopter troop added to a small ground unit can patrol an area allowing the combat unit to remain mounted and dispatch subgroup fastest to the most threatened area while still keeping an eye on the rest of its sector.

That inturn allows the larger parent unit to remain further back in reserve, maybe move from 'two up and one back' deployment ,to the more modern 'one up and two back' . With less forces engaged up front, the commander has that much more reserves to effect the out come of a tactical battle.

 

While gunship/attack helicopters were not going to make much of a differernce a troop transport chopper - like the H-21 which came into service in 1949 - might have. In the mountains of Italy the ability to drop troops behind German positions might have helped at Monte Cassino.
In the Philippines the raids to rescue POW would have been much easier with H-21s. Another tantalising use of helicopters would be during Op Market Garden. You could imagine a fleet of H-21s carrying airborne troops right on to the Arnhem bridge.
Helicopters might not have changed the war but still could have a role in speeding its end.