I’ve never seen anything like it, though the perspective is very unusual (from directly below). Nearly a square body, what might be an open cargo door to the rear, a three-boomed tail?? What looks almost but not quite like coaxial rotors. I was thinking maybe a Chinook that was angled sharply up or down, but the tail configuration isn’t even close.
Is it possible a plane or another helicopter was passing above another at the moment the pic was taken?
This was one of my favorite helicopters as a kid. My Uncle was a USAF helicopter mechanic during the Vietnam War. He later took a job with Bell helicopters in Iran, and left all of his Vietnam Era service manuals at my grandmother’s house, which I found while going through his stuff in the attic.
He had service Manuals for the Huskie, the “Flying Banana” (Piasecki H-21), and the HH-3E. The Huskie was always my favorite though, with it’s cool counter-rotating blades.
I’ve always been partial to the Kaman SH-2 Seasprite. Dad was in the Navy when they were in use. I have a photo somewhere. Dad was a Communications officer in CLG-5 Oklahoma City. A Seasprite ran out of fuel and had to ditch. I don’t know if it was going to Oklahoma City, or if Oklahoma City was just the first ship on the scene. Anyway, the floatation bags had deployed and the aircraft was inverted in the water. In the photo, dad’s wearing his swim trunks, and is helping to attach recovery gear.
My favourite helicopter when I was a kid was the UH-1D (later, the UH-1N). But I’ve always liked the Seasprite.
Any idea why the strange tail configuration? A very thick center tail boom, two thin outer booms, 4 vertical stabilizers, and a very large and wide horizontal stabilizer. Did the rotor configuration cause some kind of stabilization problems?
Ah, I see from another pic that the center boom, doesn’t seem to be a boom, but a large exhaust pipe from the engine. No idea whether the intent is to generate thrust or to route the exhaust so it doesn’t interfere with airflow over the tail surfaces. Odd that the end of the pipe is slightly pointed down.
The intermeshing, counter-rotating rotors eliminated the need for a tail rotor. (The tail rotor on a helicopter is for counteracting torque.)
The thick ‘boom’ in the middle isn’t a boom. It’s a duct that directs the exhaust from the jet engine away from the helicopter. You’ll notice that the end is turned down. This would tend to push the nose of the aircraft down. If you look at other helicopters, such as the UH-1 or UH-60, you’ll see that they have horizontal stabilizers. These can be trimmed to keep the nose in the right place. On smaller helicopters like the R22 or Schweizer 300, the horizontal stabs are fixed. (And in the case of the 300, it’s situated diagonally.) The horizontal stab on the Huskie serves the same purpose.
One problem with the intermeshing blade design is that the rotors need to be inclined. The tips come rather close to the ground. This can be an issue on a slope landing, and makes the aircraft somewhat dangerous to approach even on level ground.
IIRC the design was considered a more stable platform for operations that required prolonged hovering. Think firefighting, search and rescue, constuction, etc.
I think the primary advantage of the intermeshing rotor design is efficiency. In a standard ‘Sikorsky’ layout, the tail rotor is used to counteract torque. The tail rotor is connected to the engine through a transmission that also turns the main rotor, and requires energy to turn. By using counter-rotating rotors, all of the power can go to lifting the aircraft. (This also goes for tandem-rotor designs.)
Hmmph. I live in the town where Charles Kaman founded his little helicopter company and was at an event with him before he passed away earlier this year. Around here, the man and his company are always pronounced “kuh-MAN.”
Why have intermeshing rotors, with their difficulties involving slope landings and danger of approaching the aircraft when the rotors are turning, when these problems are alleviated in a tandem-rotor design that does not require tilting the rotors and, indeed, tend to have the rotors mounted very high?
IANA Aeronautical Engineer, but I’ll offer this non-expert theory: Tandem-rotor helicopters such as the CH-46 Sea Knight and the CH-47 Chinook have a wider CG range than helicopters that have their lift rotor(s) at the CG point. This makes them a little less problematic to load, and also allows for a ramp aft. It also makes them long.
Intermeshing-rotor aircraft like the HH-43 Huskie and the K-MAX (K-1200) do not have the CG range of the Boeing/Vertol offerings, and do not have the interior volume. They are, however, more compact. Given that their mission is air rescue and firefighting, the smaller design can get into places the larger helicopters can’t.
One thing a helicopter pilot has to be careful of is the tail rotor. In confined areas it is easy to knock it against something. This would be suboptimal. Break the tail rotor, and you’re no longer counteracting torque and you start spinning like a top. The intermeshing-rotor design alleviates this problem. The MD 520N, MD 600, and MD Explorer use the NOTAR (NO TAil Rotor) system to reduce the danger of getting the tail into the trees. The MD Explorer has a maximum payload of about 2,500 pounds, less the occupants. I think the HH-43 had a maximum payload capacity of around 4,000 pounds, but I’m not sure. I don’t know how much of the difference in payload is a function of the size of the helicopters, or the efficiency of using all of the power for lift vs. using some of the power to counteract torque.
In any case, ISTM that the intermeshing-rotor design was better suited for rescue operations than tandem-rotor designs, and that they are safer in confined areas since they do not have tail rotors. So why don’t we see more of them? I’m guessing because aerial rescue and firefighting are pretty narrow niches, and the more conventional designs perform other missions just as well or better.
Intermeshed rotors are very stable in hover, but create problems in forward flight. The rotor blades have to be very stiff to prevent contact, but that seems to be what produces the poor forward flight characteristics. The KMAX is an intermeshed heavy lift design. It works well, but has encountered a number of problems. Several units were decommissioned for various problems, and there were a few major accidents.
Kamen has been making intermeshed copters for years, and seems to be the only major advocate for the design. It does require a complex transmission to deliver power to the individual rotors, which are offset at an angle, and have to stay synchronized.
History International is showing the ‘Lost In The Arctic’ episode of Vanishings!. They pronounce the name of the airship Norge as ‘norj’. Assuming that Norge was named for the country, it should have a hard ‘g’ sound, and an enunciated ‘e’ at the end. (Dude probably says ‘Porsh’, too. )
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