This helicopter was never fielded due to some teething problems which appear to have been overcome, cost overruns leading to a per unit price of $3 million, opposition from the Air Force and other aerospace manufacturers. Its speed, range and lethal weapons package probably would have made it the weapon of choice for close air support. Of course, the Air Force was working to produce the A10. The advanced design features on the Cheyenne would reappear 50 years later in helicopter candidates for the Army.

That similar next-gen helo is the Boeing-Sikhorsky Defiant. Which adds coaxial rotors to the mix.

https://www.defenseone.com/business/2021/01/sikorsky-and-boeing-unveil-new-helicopter-could-replace-army-black-hawk/171617/

Well, the Lockheed (Sikorsky) Boeing FLRAA and FARA are interesting, but a lot bigger/heavier than the Cheyenne was. Ultimately, the latter had an untimely crash which didn't help. The Apache (which rose from the ashes in a new RFP/competition a few years after this was cancelled) hasn't turned out to be too shabby though.

Lockheed also didn't really build helicopters back then. They also screwed up on the wind tunnel testing after the fatal accident, but made a valiant effort to keep selling it for a couple years (including flight demonstrations in Europe and asia, I believe). Lockheed finally bought Sikorsky a few years ago, so they're a 'big' player in the space today.

I think the Defiant (or whatever they end up calling it if it wins. not really sure how many Indian tribes they have left that they could use. Or if political correctness would let them.) will be a good bit faster than the AH-56, even if it's heavier. The co-axial main rotors mean there's no power 'wasted' on the counter-torque rotor. All the power goes to lift and thrust. (That, incidentally, is why the CH-47 is faster in a straight line than the AH-64.)

I think the Apache benefitted from a lot of lessons learned from Vietnam, lessons that had yet to be learned when the AH-56 was being designed and tested. Mostly about survivability - armor protection, redundant systems, excess system capacity, exhaust damping, etc.

The Deifiant's competition (I forget who makes it) in the Army's Future Vertical Lift (FVL) competition is a tilt rotor. I'm not sure which has the edge in speed, range, and payload. I do know that one advantage for the coaxial rotor design is that it's foot print is smaller. This allows a single aircraft to use a smaller LZ, and to fit more aircraft in a given size LZ

The Cheyenne was sort of ahead of it's time from a control/pilot workload perspective. For the role, the pilot needs to spend a lot of time looking outside, and that control system (all analog, basically), didn't afford really what was needed. Then Lockheed botched the wind tunnel tests to fix the flexing of the fuselage/wingtips.

A lot of advanced tech, but a typical (even then) Lockheed project that probably would have been a pain to really produce/maintain in a cost effective way (see: C-5, US-101, F-35, F-22, SLS, etc.). Here's another great piece on it;

https://www.thedrive.com/the-war-zone/40014/the-cheyenne-attack-helicopter-had-a-crazy-rotating-gunners-seat-right-out-of-star-wars

And the AH 1 was the quick fix. I recall a former classmate who was assigned as a pilot to a Transportation Aircraft Maintenance company. I visited him once and he asked if I would like to go along on an AH1 that had just finished scheduled maintenance and needed a test flight. I was in the gunners seat and he took the bird out over Lake Belton and put it into a dive, then recovered. I was amazed the ship held together after the shaking.

AH-64s are still bad assed. Although, you would have to question that at least a little bit if you watched them struggle for altitude in the mountains in Afghanistan.

OH-58 Kiowas were the best and most plentiful. But they too would have to circle in order to get to the altitude where the bad guys where.

Afghanistan, especially the eastern part, was a rough operating environment for helos. Kabul is at about 4,500', IIRC, Bagram was about a mile high. Lots of mountains in N2KL and the range separating Khowst from Gardez that were up past 10,000'.

The whole country was "high hot" operating conditions in the summer during the day. (Less so at night when it cooled off.) It basically turned Blackhawks into glorified VIP transports, because they could only carry 5 troops at a time. Apaches were limited on how much ordnance they could carry. Chinooks were precious, because they had the power and lift to go over the mountains instead of having to fly up the valleys.

The T408 is supposed to be a drop-in replacement on Chinooks/Apaches. Not sure on Blackhawks being funded but I bet a re-engine initiative does happen at some point (also the T901).

This is 3,000 SHP which is a big power boost (something like 1,000 HP more per engine):

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GE Aviation continues to make strides to accelerate the program. It remains committed to the Army's goal of accelerating the testing and delivery of the engine. A team of approximately 250 employees in Lynn, Massachusetts, and Cincinnati, Ohio, continue executing on the Engineering Manufacturing Development (EMD) phase of the T901 program.

"We are extremely happy with the teamwork demonstrated by GE T901 and US Army ITE teams in reaching this key program milestone," said GE T901 Program Director Tom Champion. "We have begun rig testing of T901 product configuration components and look forward to full engine testing next year."

Earlier this year, GE Aviation and the Army successfully completed a T901 fit check of a Sikorsky UH-60M Black Hawk and a Boeing AH-64E Apache. According to Rich Crabtree, a member of the Army's ITE AH-64E Integration team, the engine "fits like a glove just like the T700."

"We continue to monitor and assess risks daily, in conjunction with GE Aviation," said Col. Roger Kuykendall, Army Aviation Turbine Engines Project Manager. "It is a true testament to GE and the government team on the work they have done to minimize delays and remain ahead of schedule."

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