With research into the future heavy lift helicopter gaining momentum there are various variations to a theme being investigated with the tilt rotor variation being main basic design variation being utilised.
One of the main problems with a tilt rotor is the power requirements for vertical lift being well in excess of that required when a tilt rotor is flying as conventional aircraft Also. the large rotor must have significant drag factor when in the aeroplane mode which inturn limits forward speed.
Using a quad tilt rotor design utilising the TP400-D6 engine together with the FH386 propellor could both provide the power required for vtol operations and when in the aeroplane mode a performance equal to that expected of the modern turboprop powered airlifter.
Surely, four 11000 hp engines driving at 10000 rpm 8 bladed propellors should move sufficient air at a thrust level to enable a fairly sizable aircraft in a vtol mode and then be operated as an efficient conventional military transport aircraft?
Heavy Lift Helicopters (HLH) are a tough nut to crack. Are you looking for a tactical lifter or an assault lifter? Are you looking to replace a fixed wing C130/A400 or are you trying to supply from the nearest runway to the front line?
In our current war the CH-53E/CH-47 seem to be the optimum lifter. Both are in short supply, and both have their limitations. These helicopters were designed from the outset for tactical resupply of fielded troops, and have done a supurb job. Helicopters are built for this type of work, theironly real limit is speed, cruise at 155-165 MPH, dash at 185-190 MPH. Whether there is a need to go faster is debatable, They supposibly were to operate under air cover (when they were designed 40 and 50 years ago respectively) and because they do their jobs so well the have been in sevice for a long time.
The tilt rotor technology is great for small VTOL aircraft, but seems to have reached a limit with the V-22. To build a HLH with tilt rotor technology can be done but is it worth it. The power requirements of such a beast (read economy) far out weigh its utility, especially when compared to the usefulness of the C130>CH53E/CH47>UH-60/Lynx combination. In war you want something that is reliable and flexible, i.e. a truck. Right now we have a tried and true delivery system big truck to medium truck to delivery truck. This was developed by the US Marines in the 1950's (and Others) perfected in Vietnam, and used very well since then.
What the HLH will have to do is fit into the current delivery system with the same reliability as the current HLHs, I do not see that in any Tilt Rotor.
Think about it.
You are absolutely right the current design of helicopters types do provide a very reliable delivery system but they have reached their design limits in regard to speed, range and capacity.
It is human nature to try and better the performance of current designs through innovation e.g. the improvements generated by the BERP rotor blade used on the larger European helicopters. I'm sure there are also US companies who are developing equally innovative improvements to existing designs.
The V-22 is one innovative design that has the potential to better the performance of VTOL transport aircraft, another is the blade tip jet powered rotor used on e.g. the Fairey Rotodyne. But, the tilt rotor needs lots of (fuel hungry) power and is also maintenance intensive and the blade tip jet is exceptionally noisy just to name a couple of problems.
In the mean time any developments to the current range of HLH's such as the CH-47, CH-53 and, the biggest of all the Mil-26, that improve the service to those in need of it will be no doubt be gratefully accepted by the operators for the foreseeable future.
What surprises me is that the European helicopter manufacturer Eurocopter have not developed a HLH to compete against the US manufacture like the competition Airbus provides Boeing in the commercial aviation arena.
A4K