"German WW2 helicopter" Topic

A few pics of a Flettner 282, RS 1/72 scale Models kit.

Pics not quite correct will redo later.
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I saw that in historical footage … Kind of neat !

A very nice kit and work

Better make sure you don't stand up in the cockpit while the rotor is still turning though!

Two rotor blades on side by side mounts? How did that work, even with steep pitched blades. Rather complicated way of doing things.

Indeed Narratio, sounds/looks complicated but the intermeshing main rotors deos away with the need for a stabalising tail rotor………..so I read………dont pretend to understand the physics myself. The basic design concept was around for a good while post war.
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dont pretend to understand the physics myself.

The 2 rotors turn in opposite directions cancelling out the torque, hence no need for a tail mounted torque rotor.

Rather complicated way of doing things.

Probably easier than doing contra rotating rotors on a single axis from an engineering point of view. Never been up close to a Kamov and IIRC the Husky to see how it was done.

Great for Pulp.

Two rotor blades on side by side mounts? How did that work, even with steep pitched blades. Rather complicated way of doing things.

They're geared together, so it's physically impossible for the rotors to hit each other unless the entire transmission fails (and you have bigger problems then!).

It gives you more lift than having a tail rotor, about 10% more, and that's really important with low-power piston engines. Turbines are much lighter for their output, which is why helicopters didn't really become a thing until the late 1950s with the Huey.

Can't work the way you have it configured there! The lower rotor will hit the column of the other taller rotor. The only way these can work if the rotors are angled enough that ONLY the rotor BLADES inter-mesh in sequence . . . and, yes, they must counter-rotate to each other to neutralize the torque.

- Tibor

Remember that rotor blades aren't flat when they're under power, their tips are elevated over the hub by a significant amount (a Huey's rotor tips are a good 5 feet above the hub, for example, and even the Bell 47 MASH helicopter gains over two feet in height at power)

Clearance *is* pretty low on the Kolibri, but it's (just) enough to keep the rotors from hitting each other.

The rotors in the pics are just resting in place so may not be lined up correctly its planned to have prop blur rotors fitted normally.
Sorry to confuse specforc12.
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Yep, been in many Hueys and later Blackhawks … Lion and Leon are correct. But even as the chopper was on the ground with rotors turning. We'd still crouch down running to get on the bird. Once all were on board they'd put pitch and we'd rapidly gain lift off. Based on the load, temperate, etc.

Worth looking at any Chinook. See those blades dropped at rest and how scarily close they do seem in some angles of attack, esp nose down.

The physics. See a conventional helicopter if it loses its tail rotor, without immediate pilot action the helicopter starts to rotate in the opposite direction to the blades. Remember Newton and action and reaction is equal and opposite?

OK, so what If you getting dizzy going around and around? Ah, it was the rotating blades that gave you any lift. They are now going much more slowly…..it is surviveable I am told. Something to do with hauling up on the collective and bracing yourself for impact. Ejector seats never really caught on for helicopters for some reason……….

Spent a lot of time in CH-47s too. Big Birds and a lot of noise. Especially when flying with the ramp open.

Choppers can auto-rotate their blades, taking the blades "out of gear" per se. Allowing the blades to still turn and in turn produce some lift as the bird loses altitude. Of course the pilots have to try to keep it level, etc. And basically try to do a controlled "crash" landing.

When operating in a hot climate like when we were in Panama. In the thin air when loaded. The UH1s we flew in had to get their nose down a bit and fly low and fast along the LZ. To gain speed to actually get enough lift to get in the air. By about 11:00 hours we may of had to reduce the load/troops. In each birds because of the hot thin air.

That makes sense, your helicopter has then become an autogyro I guess. The blades are slowing your descent, but not actively giving lift. Sounds like it would need a very steady nerve and a fast response to pull it off.

Thanks!

Yes, autorotation requires very fast reflexes to successfully pull off. It's why good chopper pilots practice it all the time.

You push the collective stick (left hand) all the way down to minimize torque on the rotor, then pull the collective all the way up right before hitting the ground so you have a little lift slowing the impact.

A Huey's rotors are actually weighted enough that you can cut the engine, take off, move over 50ft, and land again, just off of that stored energy.

Yes, you always want/hope to get very skilled and experience pilot/co-pilots flying you to an LZ. In the sometimes no so friendly skies …

Dassit.

I remember it from Chickenhawk.

Mind you I thought the first thing you did was pull up on the collective! Woops. That is the last (possibly last ever) thing you do.

Never want to experience that, but thanks for the explanation!

I had to read up on this as the photos do not show well the fact the rotor shafts are inclined outwards so that the blade misses the other rotor shaft "DURR BRAIN FADE" its a bit obvious really.