AD500 飞艇

540 FLIGHT International, 24 February 1979 AD 500 AIRSHIP ally be able to carry farepaying passengers anywhere in the world. Certification called for a lot of extra work and time, not least because to begin with there were no firm British Civil Airworthiness Requirements (BCARs). Roger Munk, chief design engineer of the AD-500, speaks highly of the CAA, which was faced with the task of writing the rulebook. He says that the Authority was helpful and always willing to see the company's point of view, pro- ducing a new part of BCAR for airships, Section Q, within about six months. Envelope THE envelope of the new airship is made from thin single-ply polyester coated with titanium dioxide polyure- thane. The fabric was developed by Aerospace Develop- ments in conjunction with two French companies: Brochier, which made the material, and Aerazur, which assembled the envelope. The material is stronger across its width, or weft, than along its length. This is desirable for two reasons. First, the best way to form an envelope is to fix together shaped strips, called gores, running lengthwise. Second, the circumferential stress in any cylindrical pressure vessel is always twice the longi- tudinal stress. Traditional materials, weaker across the width, previ- ously forced constructors to accept either an overstrong envelope or to form each gore from lots of little crosswise strips. Having produced a material with more suitable mechanical properties, Aerospace Developments can claim a simpler, lighter and cheaper solution. Another departure from convention is the use of single-ply fabric. Multiple- ply fabric has been used on previous airships to ensure some shear stiffness, which is desirable when diffusing gondola loads into the envelope. Roger Munk claims to have got over the problem by careful design of the gondola suspension. Twelve main cables made of Kevlar (a man-made fibre with better mechanical properties than glass fibre) support the gondola. The cables "grow" additional branches before being attached to the envelope by means of four conven- tional load curtains in its roof. The nose of an airship hull has to be reinforced, tradi- tionally with battens, to resist aerodynamic loading. If the craft is to be moored by attachment to a mast, the nose must also be strong enough to take mooring loads. The nose of the AD-500 is a domed disc moulded from Kevlar in a similar way to glass-fibre-reinforced plastic. This is claimed to simplify construction and save weight. The airship is designed for use with a transportable mast. The lifting power of an airship depends upon the mass of air which its hull displaces. Helium is the preferred lifting medium because although it is not as light as hydrogen, it is an inert gas and there is thus no fire risk. A balloon, which depends upon the wind for movement in the air, is best made spherical in shape because this gives maximum volume per unit envelope surface area, and I hence lowest weight. In an airship, which is driven through the air by its powerplant, the drag of a spherical shape is unacceptable and a more streamlined outline has KEY 1 Envelope in polyurethane-coated polyester 2 Bonded seams 3 Shear collar 4 Weather strip 5 Fibrelam ceiling bulkheads and floor 6 Stainless steel-cfad bulkhead 7 Gondola, Kevlar/epoxy laminate- wrapped 8 Polyurethane foam stiffeners, Kevlar laminate-wrapped 9 Welded steel tube outriggers 10 Kevlar gondola support rigging 11 Rigging equalising pulley 12 Rigging adjustment 13 Tension signaller 14 Gas seal 15 Access to gas envelope 16 Topping-up valve 17 Shot-ballast box 18 Water-ballast tank (total 1,1301b) 19 Duct to forward ballonet 20 Duct to aft ballonet 21 Ballonet control flap valves 22 Engine access door 23 Fuel tank (1 ISgal) 24 Pressure-refuelling point 25 Propulsion fan duct, rotatable through 210° for thrust vectoring 26 Duct rotation motor (4h.p.) 27 Duct rotation drive chain 28 Duct position synchronising shaft ' 29 Duct support bearing 30 Ballonet duct pressurising fan 31 Flap valves 32 Porsche engine, 190 b.h.p. 33 Tongue tube 34 Modified Lynx gearbox 35 Hoffman five-blade variable and reversible-pitch fan 36 Pitch-change cylinder 37 Blade-tip attr i t ion strip 38 Oil tank 39 Cabin heating air 40 Engine mounting 41 Engine intake air 42 Engine hoist beam 43 Electrics panel 44 Fire bottle 45 Rudder control travel-increasing pulley 46 Elevator control travel-increasing pulley 47 Gas and air valving controls 48 Gas and air pressure manometers 49 Circuitbreaker and switch panel 50 Flight instruments 51 W e a t h e r radarscope 52 W e a t h e r radar 53 Throt t le levers 54 Pitch change {mode selection) 55 Thrust vector control 56 Water-ballast dump lever 57 Envelope internal inspection dome FLIGHT International, 24 February 1979 541 M IT •Hi. ik f,^ W //'so fRANK MUN&£%. A.rtJZ.fie.S. AD500 飞艇 1.pdf AD500 飞艇 2.pdf