Would the Airwolf helicopter have worked in real life? We got expert analysis
The Fantastic Airwolf
For many children of the 1980s, the Airwolf theme song alone was enough to trigger a massive surge of adrenaline. Knight Rider was just a car, Airwolf was a freaking helicopter.
Airwolf had everything a Cold War action show should have: Stolen high-tech weapons, Colonel Gaddaffi, canyons, explosions, sexy pilots, sinister CIA operatives, and a complicated political outlook that swings between big state patriotism and rebellious libertarianism. And that theme song! Here are the credits to put you in the mood:
The helicopter was amazing, and capable of things no other helicopter was. So, with our adult heads on we ask: was it possible? We enlisted the help of Hush-Kit's tamed rotorcraft expert and former Head of Future Projects at Westland, Ron Smith, 'Could Airwolf have worked?'. Over to you Ron:
"The Airwolf TV show is a clever, exciting and much-loved creation that combines the traditional threads of the fight between good and evil, with the addition of amazing technology and the sort of action sequences that one might otherwise associate with a James Bond movie. The star addition is Airwolf – a helicopter (supposedly) capable of supersonic flight (with stealth capabilities) and with an armoury that would put an A-10 to shame. The helicopter, in effect combines with the cast and the episode plots in much the same way as the car KITT in the Knight Rider series.
Helicopter Design Process
My background comes from working on helicopter rotor design and then preliminary design of complete helicopter projects during ten years in the role of Head of Future Projects and Chief Design Engineer (Light Attack Helicopter) at Westland Helicopters Ltd in the UK. I was also a member of the Configuration Team of the NH90 helicopter during its Feasibility and Pre-Design Study (FPDS), when the UK was still involved in the NH90. One thing that this experience drove into me was that the primary concerns when designing a new helicopter from scratch are:
Mission capability
Weight
Performance
Packaging
Put another way you have to answer these top-level questions:
What does it have to do?
What equipment does that require?
How many crew are required
How far and fast does it have to fly, and in what range of conditions?
What is it likely to weigh?
How much power does it need?
What engine, rotor and gearbox technology is available?
Does it operate in a threat environment?
What does it need to survive in that environment?
Can I fit all the necessary kit in?
To answer these questions, you need a thorough understanding of the present state of the art across many areas, backed up by analysis capability including (among other capabilities) experienced designers, weight estimation capability across all the systems required, performance prediction models, survivability modelling, flight and engine control systems, crew ergonomics and anthropometry, etc.
So why is Airwolf a non-starter as a helicopter?
Reading the information available on the net (Wikipedia entry Airwolf - Wikipedia and the Airwolf Flight Manual pages Airwolf: Flight Manual Cover Page (archive.org) It is immediately apparent that the writers decided to focus on specifying the capability required to suit the TV script, with no consideration of technical constraints, availability of suitable powerplants, feasibility of control, assessment of weight or power requirements, and the packaging of the necessary systems.
In fairness, it could be said that certain Governmental procurement organisations have, from time to time, fallen into some of these same traps for the unwary. (Although Concept or Pre-Feasibility studies should, in principle, weed out the most glaringly impossible requirements and design approaches).
My approach here is to briefly review the starting point for Airwolf and then to discuss the implications of some of the postulated capabilities of the machine starring in the TV series.
The Starting Point
This is a brief summary of the capability and characteristics of the starting point. Airwolf is based on a modified Bell 222B helicopter. This is an executive and utility helicopter with a two-bladed rotor that was first flown in 1976. The data below is extracted mainly from (Janes All the World’s Aircraft 1990 – 91 and the EASA Type Certificate Data Sheet).
Its basic characteristics and Certification limitations are summarised below. Later, the claimed Airwolf capability will be discussed and compared with the actual Bell 222B capability. The plan is to follow this with a ‘what could you do about this?’ discussion, possibly with a ‘why won’t that work?’ follow-up.
The starting point is a Bell 222 helicopter with the features outlined below:
Additional assumptions: the maximum cruise speed is achieved at the twin-engine transmission torque limit (875 shp). Crew weight 100 kg (220 lb) per person. Fuel density (Avtur): 8 lb per imperial gallon – Bell 222 max fuel is therefore approx. 1,250 lb.
With two crew, max fuel and no military modifications or equipment, the Bell 222B additional disposable load is therefore 3,250 lb – 440 lb (crew) – 1250 lb (fuel) = 1,810 lb.
Airwolf claimed characteristics
The data below is drawn from the Airwolf (helicopter) page in Wikipedia (Wiki) and from a page claiming to be the Airwolf Flight Manual (FM). There are some differences between these, which will be pointed out where necessary.
The first point to note is that there is no weight statement of any kind, neither are the installed power, turbo-thruster capability, or fuel capacity stated. The turbo-thruster capacity is quoted (Wiki) as 45,000 lb-ft, which is a measure of torque (not thrust, or power).
The major claims, some of which I discuss below are as follows:
Extensive armament and equipment capability – discussed in more detail below
Capable of 300 kt in helicopter mode (Wiki/FM)
Range 1,450 miles with two crew (Wiki)
Capable of Mach 2.0 from sea level to 85,000 ft (FM) – rotor blades disengaged for supersonic flight. Ceiling 89,000 ft (pressurised)
Lifting body fuselage
Pressurised, bullet proof armoured fuselage
Stealth capability, IR suppressors
Weapons & Equipment
The extensive weapon and equipment fit cited represents a significant payload (and potential source of aerodynamic drag) not present on the original Bell 222. In some cases, they will also present some packaging difficulties.
Where there are differences between the Wiki and FM data, I lean toward the less demanding (and therefore marginally more achievable) claims. There are also some differences between the different programme series.
Fixed equipment
The so-called Flight Manual lists a very sensible collection of military equipment supporting both offensive and defensive and/or survivability features.
The table below lists the functionality provided, gives an example of such kit, and a speculative weight penalty for its carriage.
This admittedly speculative assessment indicates a ‘mission equipment’ delta mass of just over 1,200 lb before the addition of any weapons. The pressurisation implications alone, suggest that a complete structural redesign would be required.
Weapon Systems
The documents available indicate a wide range of weapons that were apparently deployed in the various series transmitted.
Guns The documents suggest wing-tip mounted guns and the Wiki information is the more believable. This calls for 4 wing-tip mounted 0.5 inch Browning machine guns – with 1,000 rounds each, an indicative mass is estimated at 736 lb. The wing-tip mounted guns are supplemented by one 30 mm cannon in each wing. An M230 30-mm cannon weighs 130 lb, with each round weighing 1.62 lb. Two M230s, each with 200 rounds would equate to a mass of 584 lb.
With these assumptions, the delta mass solely due to the gun fit is 736 lb plus 584 lb, a total of 1,320 lb.
[The FM called up 4 X 30 mm chain guns at the wing tips and two 40 mm cannon, one in each wing. The 40 mm guns would be assumed to be Bofors L/60, as fitted to the AC-130. This combination is dismissed as impracticable.]
Internal Weapon Carriage Airwolf is provided with some internal weapon stowage, with munitions being auto-loaded onto an external launching platform known as the ADF (All Directions Firing) Pod. As a rough estimate, the ADF Pod is assumed to weigh 125 lb and increase the aircraft drag by 15%. It cannot be used above 300 kt.
An extraordinary range of missiles is suggested, and these are listed below based on the Wiki information for ADF-launched systems.
The following ADF weapon loads (Wiki series 1 data) are assumed to be alternatives:
Six Copperhead rounds (each 137.6 lb) 825.6 lb
Twelve FIM-43 Redeye (each 29 lb) 348 lb
Six AGM-114 Hellfire (each 104 lb) 624 lb
Taking this at face value, the ADF load capacity is up to 900 lb.
In addition, four AIM-4 Falcon missiles are supposed to be carried.
Four AIM-4 Falcon missiles (each 818 lb) total 3,272 lb are supposed to be carried two to a side in internal bays alongside the ADF mount.
It must be questionable whether there is sufficient volume available for the 4 Falcon missiles, which are 12 ft 6.5 in long, alongside the ADF mount – an example of a packaging challenge.
Secret ‘45,000 lb-ft’ turbo-thrusters
No information exists as to the actual characteristics of these novel propulsion devices. The fact that their capability is expressed as a torque, rather than a thrust is unhelpful. To deliver Mach 2 speed capability to a helicopter (which must have at least the drag of an SUV) these devices must deliver the thrust equivalent to two afterburning turbojet or low by-pass turbofan engines, say at least the capability of two EJ200s (roughly 2X 20,000 lb thrust with reheat, weighing roughly 2,200 lb each).
At the same time, the visual space occupied by these devices suggests the same sort of size and volume associated with a very light executive jet. Let us say an Embraer Phenom 100, which is powered by two P&W PW617F1-E turbofans, each offering 1,730 lb thrust and weighing 379 lb.
This demonstrates, based on existing propulsion technology, that one is looking for engines of the same capability as Typhoon (at least) and weighing in at 4,400 lb, in a package comparable to a lightweight executive jet engine and weighing in at around 760 lb for both engines.
My conclusion is that the capability is incredible and that the supersonic performance (which exceeds that of Concorde) is equally incredible. For the purpose of constructing a mass statement for Airwolf, I am generously allocating 760 lb to the turbo-thrusters but not conceding any supersonic capability at sea level, or any other altitude.
Overall Mass Statement
Despite the guesswork involved, we can now produce a mass statement for a basic Bell 222, with its existing rotor, engines, fuel capacity and transmission system fitted with the mission equipment and weapon systems nominated for Air Wolf. Some aspects remain unaccounted for as will be noted in due course.
Note that the mass penalties associated with pressurisation, IR suppression and bullet proof protection are not accounted for. No separate mass allocation is made for the turbo-thruster fuel.
Implications
The certificated all-up mass of the Bell 222 is 8,250 lb so the figure for a notionally equipped Airwolf represents an increase of 67.6%. This will require revalidation of the static and fatigue load certification and, due to its impact on hover power requirements, is likely to lead to the need for new (or significantly uprated) engines and transmission system.
Hover power depends on weight to the power 3/2. Increasing the mass by a factor of 1.676, implies a overpower increase by a factor of 2.17. The current hover performance is delivered using a twin engine transmission limit of 875 hp; this would have to increase to 1,900 shp to maintain hover performance. This will definitely imply new engines and transmission system (including tail rotor and associated drive).
Dependent on the initial design philosophy, the rotor blade area will need to be increased to maintain the same flight envelope and retreating blade stall limits. Consequently, there will be additional mass increases to accommodate these design changes.
Knock-on aspects.
So we have a redesigned four-blade machine with double the twin-engine transmission limit. Unfortunately, exploiting this increased power in the cruise will double the fuel consumption, but (roughly speaking) only increase the cruise speed by the cube root of the power increase. This is about 1.3, increasing the cruise speed from 140 kt to 180 kt. Due to already high tip speed, the advancing blade tip speed will be close to sonic, if not supersonic. At the same time, the increased fuel consumption will reduce the unrefuelled range to around 165 nm.
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What of the claimed helicopter mode maximum speed of 300 kt and range with two crew of 1,450 miles? First, say goodbye to any notion of achieving this without the magic turbo-thrusters. At 300 kt, the drag (which dominates the cruise power requirements) will be four times greater and the power required will be eight times higher. Consequently, the fuel consumption will also be eight times greater – even without allowing for the drag (and other consequences) associated with the now supersonic advancing blade rotor tip speeds. Good luck with the stealth treatment of that.
Suffice to say, a further complete redesign of rotor and transmission system and re-packaging to store the fuel volume would be required.
In Conclusion
Airwolf is a great idea for a TV and film spectacular, but without consideration of the actual impact of the extensive mission systems and armament, or of their impact on aircraft mass, most of the postulated capability is completely unachievable based on a slightly refreshed base helicopter.
The idea of any supersonic flight capability (pushing the boundaries of Concorde and SR-71) is so risible as not to merit further discussion. Even the proposed 300 kt cruise solely in helicopter mode is a complete non-starter.
The basic credibility of the much-vaunted ‘turbo-thrusters’ is seriously undermined by the absence of any functional description and the quoting of their power in units appropriate to torque, rather than thrust or power.
As a helicopter it is fantastic – in the sense of these Collins English Dictionary definitions: extravagantly fanciful; unrealistic; incredible or preposterous; absurd."
Dr RV Smith
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