In our recent posts on the subject of helicopters we have discussed a couple of options for heavy lift, the 10-15 tonnes payload bracket.
At the lower end of that scale is the default choice of the Western world, the Chinook and at the higher end is the Sikorsky CH53K. The Russian Mi Mil-26 remains an intriguing option, perhaps one day many of the proposed joint ventures between western, Chinese and Russian companies might actually produce a workable and attractive proposition for western armed forces.
Helicopters are extremely complex, slow, expensive and very maintenance intensive but the crucial features which means military forces are willing to put up with all these is the simple fact that they can hover and land/take off without a runway.
Hovering, as opposed to vertical or ultra short take off an landing, provides so much battlefield utility that the downsides of helicopters are trumped by this single factor and if slinging loads, either dropping off or picking up, it is essential.
Recovery of personnel using a winch also makes the ability to hover an essential
We should separate the ability to hover with the ability to land anywhere, the two are not the same.
If we can eliminate the requirements to hover and relax the take off and landing requirements a tactical air lifter comes into favour, short take and landing aircraft like the CASA C235 can deliver Chinook/CH53K sized loads much greater distances, at a lower operating cost and quicker.
When I last looked at the possibility of the RAF having a tactical airlifter in the 10-15 tonne class it didn’t receive a favourable response; most of the commenters made the valid points about the cost of extra airframes, need for runways and marginal improvements in capacity over the Chinook.
With the RAF moving towards a 3 type strat/tac transport fleet of A400/C17/A330 I still think there is a gap in capability between the 10 tonnes of the Chinook and the 30 tonnes of the A400. In Richards post on Flying Cranes he floated the idea of CH53K or Super Merlin development to deliver vertical heavy lift but this still would need to hover when slinging, and slinging would be the default mode of operation.
One of the limiting factors of helicopter design is the need to counteract transmission torque, without some means of doing this a helicopter would tend to spin the fuselage not the rotor, so a number of designs have evolved. The tail rotor is the most widespread but this needs a complex transmission and bleeds power, the tandem rotor design of the Chinook has a much greater efficiency (one of the reasons they are so fast) but is still complex. Kaman have persevered with the offset intermeshing design and now specialise in sling heavy lift in the logging and power transmission installation market and the Russians have the coaxial rotor system which although a little ‘draggy’ produces some incredible performance figures. As an example look at the weight to lift ratios for the Kaman K-Max, Kamov KA32 and the proposed KA92, much better than any other conventional tail rotor type. Sikorsky have revisited their older coaxial rotor designs with the X2, modern design and materials technology have allowed an older concept to be resurrected.
With the V22, Bell have taken a different path, the XC-142 tilt wing and many more clearly shows the limitations of helicopters were well understood several decades ago but the V22 has shown itself to be just as complex, if not more complex. Cost and availability issues continue to dog this troubled aircraft.
All these solutions still have helicopter levels of cost and complexity.
One of the reasons heavy lift helicopters are often forced to sling loads and therefore have the need to hover is because, in general, their fuselages are too small. Simply making a fuselage bigger is not as simple as it sounds because more fuselage means more weight and every kilogram of fuselage means a kilogram less payload, so there is a fine balance to be struck. A bigger fuselage also means limitations in operating from ships, one of the reasons they are forced to operate from ships is because of small low range, its all a bit circular.
Loads typically hit internal volume/stress limits before weight limits. Height and width in particular, cause more problems that length.
Tactical air lifters like the C130, A400, C235 and many others generally offer greater range and speed at a much lower cost but their Achilles heel is an obvious need for somewhere to land. Even the smaller ones that can land in austere locations need a runway of some sort, these might be nothing more than a track or rough strip but it is still a relatively large area. This area has to be recce’d and prepared to some extent and for operations in theatres like Iraq and Afghanistan, this also means sanitising the area of IED’s. The larger this landing location becomes the more time consuming and labour intensive these clearance operations become. The recent resurgence in parachute delivery of stores has in part, been driven by this. The RAF have lost or damaged to such an extent that they needed to be explosively denied, 3 C130, in recent operations because of mines and IED’s, very expensive.
What would be valuable is an aircraft that could operate like a helicopter but had the payload and cost advantages of tactical airlifters.
Being able to move short, but strategically useful distances and deposit its cargo of personnel, stores and in particular, vehicles, would be a hugely impressive and useful capability and could provide a serious alternative to many of the amphibious capabilities we currently have.
I wouldn’t view this as a helicopter but more of a light tactical air lifter with very very impressive short field performance.
One possible solution might be to resurrect an old design, the Fairey Rotodyne.
Insane you say…
I might usually agree, these older designs have suffered at the hands of evolution, if they were so good why aren’t we using them today but like balloons, given the advances in computer aided design, simulation, materials technology, computerised flight control systems and engine power, is an old but proven design concept like the Rotodyne viable today?
The Fairey Rotodyne
In the post war period the British aeronautical industry was a fertile breeding ground for innovative designs. Out of this environment came the Fairey Aviation Rotodyne. It was designed by Dr J Bennett and Captain G Forsythe using the lessons learned from the record holding Fairey FB-1 Gyrodyne and Jet Gyrodyne. The FB-1 first flew in 1947 and the Rotodyne in 1957.
The Rotodyne featured a large 4 blade rotor with each blade having a tip mounted nozzle that channelled compressed air from the stub wing mounted turboprops. Because the tip nozzles were not directly coupled to the engine no counter rotating torque was generated, negating the need for a tail rotor. In normal flight the rotors would be unpowered and the pitch reduced to reduce drag, when landing or taking off the rotor would be powered to allow vertical landing or take off. It could also fly with one engine out.
Performance was impressive, 48 passengers, cruise speed of nearly 200mph and a range of over 500 miles.
Compare that with the Chinook still being used 50 years after the Rotodyne was cancelled, similar number of passengers, cruise speed slightly less and a range of about a hundred miles less, with more power.
If the words ‘ahead of its time’ could be used to describe any aircraft, the Rotodyne would be it.
Towards the end of the fifties, despite it demonstrating incredible performance, the need to reduce costs and reduce the number of aircraft manufacturers placed it firmly in the centre of a political and economic storm from which it did not emerge, being cancelled in 1962.
For a full description click here
What Would a Modern Rotodyne Look Like
The concept has been kept alive by a couple of US manufacturers, Carter Aviation and Groen Brothers Aviation although there are technical differences between the two approaches. The Carter Slowed Rotor Compound concept has very recently been licensed by AAI for use in unmanned designs, will be interesting to see what comes out of this.
In 2005 the US announced the Joint Heavy Lift program which envisaged an aircraft with the payload of a Hercules but with STOVL capabilities. Yet another alphabet soup of programmes has followed but has been beset with by a lack of definitions and operational concepts, is it a helicopter or is it a tactical airlifter?
The Groen Gyrolifter is the closest to the Rotodyne concept but was rejected from the programme, one wonders if it is because the design means it would be unable to operate from USMC amphibious vessels and therefore would not be very ‘joint’
The programme changed to Joint Future Theatre Lift and there was a realisation that vehicles were getting heavier and the Future Combat System was heading for the scrap heap. This coincided with concepts around future tactical airlifters (AJACS) and no surprises, its all in the PowerPoint stage. The Army wants vertical lift, the USMC want the same but it has to be able to operate from ships and the USAF just want something cheap.
The Sikorsky Quad Tilt Rotor seems to be the front runner but given the issues around the V22 and obvious budget issues there does not seem to be much appetite to pursue it. If the twin engine V22 is eye wateringly expensive a version with double the number of engines would be astronomically expensive.
Looking back to the Rotodyne its performance is comparable with a Chinook so why bother?
Clearly it must be in the 20 tonne Hercules payload class.
The Groen Gyrolifter proposed taking a C130 and modifying it, producing a C130 derived aircraft that could carry 18 tonnes a distance of 1,100miles or 1,000 nautical miles. Whilst this is impressive it fails to improve on the volume limitations of the C130 that have driven, in part, the need for larger aircraft.
If there is room in the equipment plan for such an aircraft it should be as simple and low cost as possible but it must have a large internal volume.
Aerodynamic efficiency and the need to exploit this efficiency by flying high means that the slender cylindrical tube is the preferred fuselage configuration. Cylindrical shapes make pressurisation, for more efficient high altitude flight, much easier but results is volumetrical inneficiency, look at a vehicle inside a tactical transport aircraft like the Hercules or C235 and it becomes obvious that even when fully loaded, it is transporting a lot of fresh air.
Pallets and vehicles have square cross sections, not round.
Without the need for high altitude and high efficiency flight profiles the designers of helicopters tend to make their fuselages less cylindrical and squarer. If we accept the trade off of medium altitude and unpressurised flight profiles the fuselage can be square and therefore closer matched to payloads.
This would lead to a new fuselage design with a square cross section.
mmm, this is sounding expensive!
But whilst we are all sucking our teeth and asking ‘how f**king much?
Consider this, the map shows 1,100mile radii from Gibraltar, RAF Akrotiri, Al Udeid Airbase in Qatar, the French airbase in Djibouti and Masirah Island in Oman.
Draw your own maps, here
Gibralter (36.1833, -5.3667), RAF Akrotiri (34.59027777, 32.98749999), Al Udeid (25.11722222, 51.315), Djibouti (11.547331, 43.159481), Masirah Island Oman (20.471111, 58.815278), RAF Mount Pleasant (-51.82222222, -58.44166666), Lungi Airport Sierra Leone (8.616444, -13.195489), Ascension (-7.933333, -14.416667), St Helena (-15.933333, -5.716667), Belize (17.51555555, -88.19583333), Al Udeid Qatar (25.117222, 51.314722), Turks and Caicos (21.75, -71.583333), Cayman Islands ( 19.333333, -81.4), British Virgin Islands (19.333333, -81.4), and Anguilla (18.21027777, -63.057)
Range could of course be extended with buddy refuelling or conventional airborne refuelling.
Any takers?
The heavy VTOL lift niche doesn’t justify the development and procurement expenses which are necessary for a new aircraft.
Heavy lift helicopters are nice tools, but they are simply too expensive.
gloalsecurity.com:
“Marinized heavy lift currently comes at a very high price. On average, every hour a CH-53E flies costs the Marine Corps approximately $20,000 and requires 44.1 maintenance man-hours.”
I think one of the key design drivers for the CH53K was a significant reduction in maintenance
So CH53E is cheaper than Merlin to run?
x, you would be comparing apples and grapes. All helicopters and maintenance heavy because of the high pressures and moving parts
i would’ve thought that development and procurement costs could be eaten up as this has, as shown in the video huge civilian potential as well. city airports and just airports in general are struggling to expand hey ho no runway required so the tree huggers can cut the chains and go home!!
Also the groen website states that most of the certification is not required as they are existing aircraft. When you think about it the main gripe (blatant lie) was the noise from the rotor tips well it’s 55+ years since the fairey so i reckon we’ve got that sussed and as for engine power for the stub wings well we spent a bucketload on getting the A400m ebgine squared away and that kicks out 11,000+ shp, So lets get it built who knows might even win a US contract (it’s friday, it’s late and i’ve had a beer).
Bae have got some spare aircraft engineers/designers
A rotodyne sounds like a great solution, but I suspect will never happen with public funding: mainly because the A400 would be rapidly squeezed out of the theatre airlift role and that would offend the powers that be (largely the politicians and the RAF). A private venture solution might well do very well however.
If memory serves, one of the issues with the Rotodyne was the noise from the rotor tip jets. Rolling takeoffs might well mitigate this however. Will dig further…..
Theres a good history of the Rotodyne as a PDF here; http://www.gyropilot.co.uk/downloads/Rotodyne%202%20RTF%20Mod.pdf
“Whilst this is impressive it fails to improve on the volume limitations of the C130 that have driven, in part, the need for larger aircraft.”
Why not utilise the proposed C-130XL fuselage in the same Rotodyne configuration?
http://www.flightglobal.com/articles/2008/09/22/316314/picture-lockheed-martin-unveils-wider-larger-c-130xl-to-fight.html
It is true that modern helicopters, are mechanically complex items, one of the main problems is the mas production and adoption of specific types that sets the ‘mode’. Its not that this is the best design, but the one chosen by the most prolific manufacturers who cornered the market. A case of the VHS versus Betamax, the best does not always win.
The most popular type is the ‘Penny Farthing’, with the large main rotor and smaller tailer rotor, which Admin quite rightly points out ‘bleeds power’.
To rid the need for anti-torque all you need to do is remove the torque reaction by shifting the thrust to the end of the rotor blades. This was described above on the Rotodyne, but it was also used on smaller helicopters such as the Sud-Ouest SO.1221.
Instead of driving a gearbox, the gas turbine powered a compressor, which fed air to nozzle tips at the end of the blades. This removed the need for anti-torque and significantly reduced complexity and weight. I believe the only problem was the noise was deemed unnacceptable for civillian operators, not a problem in military circles.
Perhaps it is time to look at the Sud Ouest configuration with regards to heavy lift? An S-64 Skycrane with nozzles athe blade tips and no parasitic tail rotor would definitely have a lift capability advantage over the ‘traditional’ designs.
http://www.aviastar.org/helicopters_eng/snias_jinn.php
if something between the chinook and the A400 is required, combining the best qualities of both, then the quad tilt rotar looks tempting if only because it should be capable to carrying internally what i consider the becnmark:
a bronco.
I have one word for you – AIRSHIPS !
UK is world leader in design and build of modern hybrid airships – if you want long range, quasi-strategic vertical lift, its the only way to go
Some Youtube-stuff to add
admin said “x, you would be comparing apples and grapes. All helicopters and maintenance heavy because of the high pressures and moving parts”
I know. It was a throw away statement to see if anybody would bite…..
Why do the RAF love the A400m so much?
As an aside, if only we could fix the Kamov Ka-92 rotor and drive system on top of a Merlin……
….now that would be a decent piece of kit.
@Jedibeeftrix – Tilt rotors have a very chequered history and the V-22 certainly doesn’t inspire confidence in the concept. A Quad tilt rotor will probably never happen
BTW, are you PAID by ST Kinetics?
lol, much as it might appear otherwise I am not in fact a member of ST Kinetics sales team.
I’ve been lurking on this blog for ages, thought it was about time I made a comment! I’ve always thought that a Rotodyne type aircraft was a much more logical evolution of the helicopter than the tiltrotor concept. But Jed really hits the nail on the head: Airships!
Welcome to TD Nick, might do a post on airships in the future then
If the airship and Fairey Rotodyne are being resurrected why not the Armstrong Whitworth A W 681? Re-engine the Embraer KC-390 with two or four F135/136s and you have a VTOL C-130 equivalent.
If the “cuts,” sorry review, goes as some think “the” entire army battle group will be able to lifted into theatre in the RAF’s only Storch. But only on Tuesdays and Thursdays. Monday and Tuesday the Navy will have the Storch; not to fly just to polish. Fridays it will be hired to the Royal Mail PFI buy out to deliver parcels…..
Am I the only one who thinks airships are a really bad idea? I’m thinking WW1 Zepplins getting shot shot down, lumbering speeds, weather limited.
The AAC tried using airships back in the 90′s, I think the fact that they dropped the idea speaks volumes.
Brian, the AW 681 was very similar in concept to the YC-14/15 competition. Although it fell on its a*se, it eventually resulted in the C-17 Globemaster. I can’t see it being funded when the A400M is struggling as it is.
Richard,
WWI Zeppelins were built as light as possible in order to have a reasonable payload/ceiling/range and also to avoid fighters- the height climbers (hence the large number of structural failures, eg the post-war R-38 tragedy, if not handled carefully).
But the Graf Zeppelin and Hindenburg were safer than their heavier than air contemporarires when captained by Eckener and Lehmann.
The downside of cargo airships is their sheer volume to payload ratio. The bigger the airship the larger clear area needed for take-off and landing (or hover with skyhooks, really!) For a C-5 size payload, a landing field at least as long as a C-5 runway is needed.
My modern AW 681 is not based on the Medway version (the YC-14/15 progenitor) but on the Pegasus version – V/STOL not STOL.
Richard, technology has moved on somewhat since pre-WW1 days !
http://militaryairships.blogspot.com/
However, just like any other platform / technology heavier than air hybrid airships are NOT a silver bullet. But if your talking HEAVY lift, then yes an airship capable of carrying 1000 tonnes will need a 5000 strip – but not concrete and remind, how much less than a 1000 tonnes can a Galaxy carry ?
Brian, the more I read about your AW 681, the more reasonable it sounds. I’m sure Dornier or Fokker did something similar with pylon mounted Pegasus engines….just checked, it was the Dornier Do-31.
Mind if I make a small suggestion/alteration to your proposal? Rather than using bi-furcated rear nozzles, use a singular rotating nozzle as used on the F-35B. This combined with the two front nozzles would still provide stability and be more efficient with regards to thrust.
Pie in the sky stuff I know, but hey….a good idea is still a good idea.
Richard,
Many thanks for reminding me about the Dornier Do-31. My proposal to have four engines is a practical one as I recall Bill Bedford saying once that a VTOL aircraft with engines under the wings would be fine until an engine failure, when it would then gain the record for rate of roll!
Now if I’m allowed pie-in-the-sky I vote for Thunderbird 2.
Brian,
Thunderbird 2 doesn’t seem far from a decent requirement, the only major problems seem to be ground erosion and ground clearance. Gerry Anderson definitely had vision, especially with the fore-swept wings.
I don’t know if you saw my piece about Flying Cranes (modular helicopters), I argued for a CH-54/S-64 Tarhe Skycrane based on the forthcoming CH-53K. A skeletal airframe with interchangeable, modular pods dependent on the role. I also highlighted the Kamov Ka-226 light helicopter, and also suggested the Merlin being a possible starting point.
Admittedly not a patch on the Thunderbird 2, but definitely a close runner in the rotary sense.
http://www.thinkdefence.co.uk/2010/09/flying-cranes-time-to-take-another-look/
My favourite for the future of rotary aviation is the mock-up of the Kamov Ka-92. Contra-rotating rotor blades and rear-mounted props, all fixed atop a troop carrying fuselage – what more could you want!
I’ve said it before, and undoubtedly I’ll say it again some time in the future, but we’re starting to hit the upper technological limit with helicopter design so we’ve got to start looking at alternatives and begin to innovate. I guess that’s the same for fixed-wing aircraft.
Interesting paper, excepted the fact that you forget the recent Boeing-Eurocopter proposal for an oversized Chinook-like heavy lift helicopter with 15t payload :
http://www.flightglobal.com/articles/2010/06/09/343011/ila-eurocopter-reveals-chinook-style-heavy-transport-helicopter.html
Hi BPC’s, welcome to Think Defence
We referenced the Euro heavy lift proposal in earlier posts on the subject
http://www.thinkdefence.co.uk/2010/09/a-helicopter-strategy/
Jed
I’m a big fan of airships, but they are not helicopter replacements.
They arent really even C5/A400 replacements.
What they are, is a Point Class replacement/supplement.
There use would be to move heavy/none urgent equipment between bases at little cost.
Tank Regiment from Germany to Shrewsbury, Afghanistan or Canada. Not a problem.
I though that the main problem with noise from the gyrodyne was that it didn’t just pipe compressed air to the blade tips but it also burnt fuel there too, the noise created by what was effectively 4 afterburners would be deafening.
How about, a boxy unpressurised fuselage sized around admin’s favourite 20ft Iso container?
Also if we’re talking about ressurecting obscure VTOL/STOL concepts, I’ve seen some recent UAV concepts incorporating Fanwings and also what about variable incidence wings. I think the USN Corsair II fighter aircraft used it and I saw it on some of the initial concepts for the JFTL. Increasing the incidence of the wing by a few degrees is alot simpler than tilt-wings and coupled with some sturdy undercarriage and blown flaps could give you some really impressive STOL performance
Just to beat the drum again, rather than PFIs galore (especially the tanker boondoggle), why not a leveraged buyout of Groen Bros.? Get the remains of Rotodyne IP back in British hands.
Jed et al.,
I must be a deacon in the church of airships by now. For all sorts of applications, and particularly for the “world’s fastest sealift” category. (Why say sealift, besides annoying jet-engine supporters? Because for both speed and security, you’d want as much of the transit to the theatre of operations to run via the airstreams over open ocean as possible. Same for commercial carrying trade.) And yeah, a proper loadmaster team aboard a fully realised version of, say, the now-old SkyCat 1000 design would pack one airship with about five times the most heavily-loaded C-5 you’ll ever see.
So, you want to move a follow-on brigade fast? Have the Points in RFA livery at last, ready to pick up heavy gear at a prepo site, and move everything else (lighter gear, personnel, all your sustainment materiel) by airship. Be bloody useful to get modern Rotodynes aboard an LHD, though. Four to six of them in place of a squadron of Junglies. Need a mother of an elevator system, but we can dream. (For the sort of airlift Admin’s describing I suspect you’d be better off with A400M in quantity. But for on-point expeditionary air, Rotodyne would be a happy choice. Do the job better than an Osprey.)