By Gavin Bull, Aircraft Propulsion Specialist


In the dark days of the late 1930’s when the clouds of war gathered over Europe, Frank Whittle was busily conducting tests on his brainchild, The Jet Engine, which would revolutionise air travel. Meanwhile, in a muddy field in Gloucestershire, Bill Grundy was dreaming along similar lines. Grundy was a pig farmer and he had made the stunningly original observation that the gaseous ejections from his pigs was mainly methane. Grundy realised that if he could somehow harness and utilise this source of fuel, then he could achieve the Valhalla of Aeronautical Engineering – Porcine Aviation.

If only he could develop a reliable and workable propulsion system for his pigs, then the world would indeed be his oyster. A Fellowship of the Royal Aeronautical Society and even Presidency of the Society of British Aerospace Companies would await him and he would be feted across the Atlantic as the true descendant of Orville and Wilbur Wright.

Grundy knew that he would have to accurately mathematically model his pigs’ methane production and so set about gathering empirical data. He took ten of his best pigs and fed each one on a different diet, while rigging up a methane collection apparatus in his pigsty. After three weeks, he discovered that the pig on an ‘unpasteurised milk and cinnamon’ diet produced vast quantities of methane, but this pig spontaneously combusted one night during a violent electrical storm.

Grundy was ready for flight testing … he converted a couple of old metal funnels into a convergent-divergent nozzle, added an ignition source of a couple of old spark plugs and strapped the entire contraption to the back of a pig. The pig was mounted on a sled and then placed on a ramp. When the pig was ready, Grundy connected the spark plugs to an old car battery and ... ‘We have ignition!’. The pig rocketed up the ramp, before tipping nose down and creating a large crater in the field, after a total flight distance of ten feet, a maximum altitude of four feet and a terminal velocity of 150 feet per second.

Despite the loss of the prototype, Grundy was elated – he had proved that pigs could indeed fly, he just needed to iron out some development problems before series production of his ‘External Combustion Pulse Detonation Engine’ could begin in earnest.

To be continued ….?

By Nick Holdaway, based on spoof ATP report from British Regional Airlines


Undaunted by technical realities, the design team at Porcine Aerospace (PAe.) has announced plans for the PIG-XL, promising more noise, reduced payload, lower cruise speed and increased pilot workload.

We spoke to Mr. Fred Gribble, former Railtrack employee, and now Chief Project Engineer. Fred was responsible for developing many original and creative design flaws in the service of his former employer, and will be incorporating these in the new PIG-XL technology under a licensing agreement. Fred reassured PIG pilots, however that all the fundamental design flaws of the original model had been retained. Further good news is that the XL version is available as a retrofit option.

Among the new measures is that of locking the ailerons in the central position. Following simulator and flight tests which showed that whilst pilots of average strength were able to achieve up to 30 degrees of control wheel deflection, this produced no appreciable variation in the net flight path of the PIG. Thus the removal of costly and unnecessary linkages has been possible, and the rudder has been nominated as the primary direction control on the XL.

In keeping with this philosophy, but to retain commonality for crew’s transitioning to the XL, additional resistance to foot pressure has been built in to the rudder bias system to prevent over-controlling in gusty conditions (defined as those in which wind velocity exceed 3 knots).

An outstanding feature of PIG technology has always been the adaptation of the PW100 engine, which mounted on any other aircraft in the free world is known for it’s low vibration levels. The PIG adaptations cause it to shake and batter the airframe, gradually crystallising the main spar, lock the left hand main gear after retraction, desynchronise the accompanying engine and simulate the sound of fifty skeletons fornicating in an Aluminium dustbin. PAe. will not discuss the technology they applied in preserving this effect in the XL but Mr. Gribble assures us it will be perpetuated in later models and sees it as a strong selling point. "After all the Concorde makes a lot of noise" he said, "and look how fast that goes."

However design documents clandestinely recovered from the PAe. shredders have solved a question that has puzzled aerodynamicists and pilots for many years… how does the PIG actually fly? These documents disclose that it is actually noise which causes the PIG to fly – the vibration set up by the engines, and amplified by the airframe, in turn causes the air molecules above the wing to oscillate at atomic frequency, reducing their density and creating lift. This can be demonstrated by sudden closure of the throttles, which causes the aircraft to fall from the sky. As a result lift is proportional to noise, rather than speed.

Mr. Gribble was at pains to point out that during the take-off phase, the previous equation is not applicable as the net take-off flight path is completely proportional to the willpower of the flightdeck, cabin crew and passengers combined. "Any single person not willing the aircraft to become airborne could cause a major accident, " he commented.

In the cab (as Gribble describes it) ergonomic measures will ensure that long term PIG pilots' deafness does not cause in-flight dozing. Orthopaedic surgeons have designed a cockpit layout and seat to maximise backache, en-route insomnia, chronic irritability and terminal (post flight) lethargy. Redesigned ‘Bultworker’ elastic aileron cables, now disconnected from the control surfaces, increase pilot workload and fitness. Special noise retention cabin lining is an innovation on the XL, and it is hoped in later models to develop cabin noise to a level which will enable pilots to relate ear-pain directly to engine power, eliminating the need for engine instruments all together.

We were offered an opportunity to fly the XL at PAe’s secret development facility in the West of Scotland, however all PAe. aircraft are prohibited from flying in Scottish airspace during the avalanche season, so the test flight was carried out over the Irish Sea. For our mission profile the XL was loaded with Benbecula passengers for a standard 100 nm trip with normal Railtrack reserves, carrying three pilots (all captains due to crew shortages) and 68 + 40 passengers (all from the same family) to maximise discomfort.

Passenger loading is unchanged, the normal ‘prop rotating in wind of 5 knots, due to slack groundstaff failing to secure it’ syndrome, inflicting serious lacerations on 71% of boarding passengers, and there was the usual confusion in selecting a seat appropriate to the nearest emergency exit. The facility for the clothing of embarking passengers to remove oil slicks from engine cowls during loading has been thoughtfully retained on the XL.

Start-up is standard, and taxiing, as in the standard PIG is accomplished by brute force. Take off calculations called for a 250-decibel power setting, and the rotation force for the (neutral) C of G was calculated at 180 ft/lbs. of backpressure.

Initial warning of an engine failure during takeoff is provided by a reduction in vibration of the flight instrument panel. Complete seizure of one engine is indicated by the momentary illusion that the engines have suddenly and inexplicably become synchronised. Otherwise identification of a failed engine is achieved by comparing the vibration levels of the windows on either side of the cabin. (Relative passenger pallor has been found to be an unreliable guide on many PIG routes because of ethnic consideration).

Shortly after takeoff the XL’s chief test pilot Capt. Horrendous demonstrated the extent to which modern aeronautical design has left the PIG-XL untouched; he simulated pilot incapacitation by slumping forward onto the control column, simultaneously applying full right rudder and bleeding from the ears.

Whilst initially noticing nothing out of the ordinary, on discovering that Capt. Horrendous actually was incapacitated, the crew of the XL discovered that, like it’s predecessor, it demonstrated total control rigidity and continued undisturbed. Power was then reduced to 249 decibels for cruise, and we carried out some comparisons of actual flight performance with graph predictions. At 5000 ft and ISA, we achieved a vibration amplitude of 500CPS and 240 decibels, for a fuel flow of 700 kgs/hr making the PIG-XL the most efficient converter of fuel to noise after the Titan rocket.

Exploring the Constant noise/Variable noise concepts, we found that in a VNE dive, vibration reached its design maximum at 1 000 CPS at which point the limiting factor is the emulsification of human tissue. The catatonic condition of long term PIG pilots is attributed to this syndrome which commences in the cerebral cortex and spreads outwards. We asked Capt. Horrendous what he considered the outstanding features of the XL. He cupped his hand behind his ear and shouted "Whazzat?"

We returned to Porcine Aerospace, convinced that the XL model retains the marque’s most memorable features, whilst showing some significant and worthwhile regressions.

PAe. are not, however, resting on their laurels. Plans are already advanced for the BOAR-XL and noise tunnel testing has commenced. The basis of preliminary design and performance specifications is that lift increases as the square of the noise, and as the principle of acoustic lift is further developed, a later five-engined vertical take-off model is also a possibility.

Porcine Aviation Files : OldMacDonald-Dugless, Boaring & Swillair; CAA suggests pigs might not fly!
Porcine Aviation Files II: Pioneers of Porcine Aviation
Porcine Aviation Files III: Piggles of The Royal Porcine Flying Corps
Porcine Aviation Files IV: Ovine Aviation - The Sheep Strike Back
Porcine Aviation Air Force Marching Song


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