The only drawing that is not included is the sail plan. Right from the onset of this project it was felt that the sail was the component that it would be impossible for the majority of Homebuilders to build. It would require full scale Mylar plans, which would be prohibitively expensive, specialist sewing machines and a great degree of inspection which would be virtually impossible to achieve. The sail is available from Hiway Light Aircraft, extremely competitively priced, in a wide variety of colours. Cost approx. £1170 (UK pounds) Some other fabric parts which can benefit from commercial construction are the seat fabric and any "skirt" that is required at the rear of the pod.
All the tubing used was to the British specification HT30 TF mandrel drawn tube, with the exception of the Trike frame which is HE 30 extruded square tube sleeved in places with round HT30TF. For people building this aircraft abroad it will be their responsibility to ensure that the materials are comparable to this specification and it may be necessary to retest some of the airframe if it is not possible to proof the suitability. The round tubing used in the Wing is mainly 17g imperial tube as this allows the various diameters to easily sleeve the next size up or down. This is consistent with normal Hang glider construction.. The maximum diameter (crosstubes)is 25/8" sleeved with 21/2". The leading edges are a composite of 21/4", 21/8", 2", 17/8". The A frame sides are 13/4" and the A frame bottom is 11/8". The Kingpost uses 11/8" and 1" sleeving. The Keel uses a composite of 21/8" 2", 17/8" and some 13/4". The Fin is 1". There is some HE30 channel and some HS30 1/8" and 3/8" plate. There is some mild steel square tubing used in both the steering assembly and the engine mounting. What tools do I need and is there any welding, turning or other specialised work? The engine mounting and the steering components require some welding, normally either gas or TIG, although MIG may well be acceptable. There is also a minimal amount of turning required, mainly nylon 66 and small amount of Aluminium and steel. The seat frame requires the use of a Hilmor type pipe bender capable of bending 11/8" x 13g HT30TF tubing. Most builders get this done commercially.
In Britain there is a series of Senior Inspectors nominated by the BMAA and the construction of the machine is overseen by one or several of these inspectors. Only when a number of series inspections have taken place satisfactorily will a Permit to Test be issued. An approved pilot will then be required to test the aircraft and a minimum of 5 hrs will be required before a full permit is issued. In many cases this flying can be performed by the builder. This careful inspection and testing is particularly important where the builder is inexperienced or in some cases this is his/her first encounter with an aeroplane. How much will it cost me? The plans are £110 UK pounds plus the post and packing which will depend on your locality. I can only accept Bankers Draft from abroad and this should be Sterling and made out to J A Hunt. The plans describe the construction for a 440 Robin engine but are easily adapted to the 503 Rotax or the 462, or the 582. The sail is approx. £1170 plus appropriate p&p and is available from Top Flight Sails Tel/Fax 01495 306431.Hiway Light Aircraft, Longtown, NR Hereford. UK. 01497 851671 are able to supply both tubing and other parts. At the moment the cost of building a Huntwing complete with new 503 Dual Carb, Dual ignition (the favourite for most UK builders) complete with electric start (£500) and full instrumentation is working out at about £5500 to £6000. This would be the equivalent of a machine costing £12,000 to £14,000 at present. Using some second-hand parts, particularly the engine, pod and instruments, can decrease the overall cost dramatically.
The front wheels uses 4 springs. The rear axle does not have suspension, only the tyres. This has not proven any problem and cuts down on the weight.
At present there are 100+ sets of plans issued and there are 12flying in the UK and 4 or 5 in Eire. There are also several being built in the States, Australia,Tasmania, Sweden, Holland and Italy. There are many more just about ready to fly.
The MAUW design and tested is 372Kg's and this allows for 50 litres of fuel and 2 x 90kg pilots with some personal equipment. If you build it a bit heavy, too many instruments, electric start, battery, heavy or large pod, then you will have to either reduce fuel capacity or restrict passenger weight)) In Britain it is now considered acceptable to use 86Kgs as the average weight of the occupants and so this will allow a slightly heavier build providing you are not over 86 KGs. Whichever way it is important to know that 372 KGs is the tested weight. It is also important to understand that the Max wingloading currently allowed by section S is 25 Kg's per Metre 2. This wing is exactly the right size for this loading at 372kgs. However by June we should be in line with the new Section s which will allow weight and balance and, provided that the stall speed is below 35miles per hour, any wing loading. The MAUW will also increase to 450Kgs but of course this would require the aircraft to be retested to that weight.
The majority have used the Rotax 503 engine but there is also 2 462's, 1 582
, several 447's and Robin 440's. I would recommend using the 503 as a minimum
and the 582 really motors. 1500ft a min with one on board and 800 with 2. The
462 engine weighs in around 42 to 45Kgs when you take everything into account.
On my own trike(462) which uses a copy of the Quasar pod (Full length glass
fibre) with lots of instruments, radio, electric start, battery, GPS etc. the
total all up weight is right on 372KGs with 2 86KG occupants. Perhaps the most
common question relates to the use of BMW engines taken out of motorbikes and
modified but they are very heavy. The lightest BMW is the R100RS will weigh
perhaps 72KGS with an appropriate reduction. See The
BMW story. The VW engines are considerably heavier again. The Jabiru engine
may well be OK as it is considerably lighter but I feel that it would probably
need a reduction drive (putting the weight back up) or else you will be driving
a very small diameter propeller which is both noisy and inefficient. There is
a new 4 stroke due out in April 1998 from Motavia which claims to be the answer
to all our prayers i.e. only 52KGs all up 80HP , spares off the counter from
Ford dealers, Bolt compatible with Rotax and TBO of 1000 hrs but this is early
days and we will have to wait and see. As they haven't yet offered me a free
test sample I will reserve judgement. There is also a Czech 4 stroke (SVS 1400)
which is slightly heavy but is claimed to run on 6 litres an hour. Details from
Milan Stavenik in the USA at AKS
aviation.. It can also be run on propane if you like.
The new HKS engine looks a good possibility and this will be available later this year from both Pegasus Aviation and Thruster UK. Raven redrives are able to supply areduction unit for the Suzuki Swift engine (Geo Metro) and this looks like a very interesting possibility. Check them out on www.raven-rotor.com
A fairly new company is also supplying 2 stroke engines from Italy on www.zanzotteraengines.com.
One final consideration when stepping away from the tried and tested is the possible requirement for noise testing. In Britain the tested aircraft use the Robin 440 with 2.77:1 reduction and a Nicklow Propeller and exhaust. The 462 Rotax with 2.58:1 and 64" 3 bladed Ivoprop, the 503 with the same and the 582 have all achieved noise certificates. You need to check out any noise regulations before trying different engine types.
The VNE is quoted at 72mph which may seem a little slow but this is for good reason. The VNE is calculated as 90% of the top speed achieved and originally the fastest I was prepared to push the aircraft to was 80 or 81. The machine is extremely positive in pitch and to achieve this requires a fast spiral dive. I have subsequently achieved between 85 and 90 MPH so I suppose the VNE could be increased. This 72 MPH is achievable in straight and level with the 582 so it has a good cruising ability and indeed with my 462 I normally cruise at 55 to 60 sometimes 65 if its a bit windy and occasionally 70 if its a gale. Please bear in mind that the VNE quoted on most commercial Trikes is almost unachievable and is not an accurate reflection of its actual cruise speed. The stall speed is 28MPH. I am currently working on a new faster version of the wing but it is very early days. This will probably be based on the same airframe with a new sail design. I know how to make the current wing faster it is just a case of how safe will it be and also the speed, at cruise, is dependant on larger HP engines. There is currently one derivative capable of sustained genuine 70MPH cruise.
Given that the 462 variant is capable of at least 4 hrs sustained flight fully loaded there is not a problem with range
The best looking examples, to date, have been from people who are engineers for a living. Having said that so are the worst. There have been several extremely good looking machines built by people from all walks of life. The minimum time that I could build a new one from scratch would be approx. 300hrs. To get a really good finish takes longer. It is also dependant on how much work you do yourselves and how much you buy in. I.e. I actually made the Quasar pod and it probably took me 150hrs. I could have bought a very good pod for between £50 and £200. The time consuming part is the electric's, the instruments, the trim, the fuel system and the water cooling system. (Save some time by using an air cooled engine)
The Huntwing was only designed and tested to 372KGs. Some parts would need redesigning and strengthening and a complete retest would be required. As the wing is designed to exactly 25KGs per square meter this may also need increasing. The new rules may remove this hurdle and replace it with a maximum stall speed. Dependant on this speed allowed this may remove one problem.
There is room to build the Trike upto 4" longer than the original and this is thoroughly explained in the construction notes and plans. Again the MAUW is 372 so that provide you fly single seat, or with a suitable small passenger, there will be no problem. You could also reduce the fuel capacity. At the other end of the scale the aircraft can be flown with a 70KGs pilot but if you wish to carry ballast you may. Personally I feel no requirement to use ballast in any conditions.
The aircraft is extremely stable in even the worst of turbulence and whilst not quite as light, in roll, as some commercial aircraft its directional stability at all speeds is second to none. This means that less input is required to achieve adherence to track. I have never suffered any form of fatigue whilst flying it which is more than can be said for many of my friends on commercial wings. Speedwise this is comparable to all similarly engined contemporary commercial Trikes.
There are no plans to produce single seat plans
Purchasing second-hand can be very tricky, particularly as the 2 stroke engines need good maintenance. Building your own aircraft can be more exciting, for some constructors, than actually flying. When you eventually take to the air and start flying long distances on a machine, built by yourself with your own individual touches, there is no comparison with the thrill. If you should be unfortunate and bend the aircraft you can legally build all the parts at much reduced cost by comparison to commercial aircraft. For example replacement monopole for the Trike approx. £30 Max for Huntwing, approx. £180 + for most commercial aircraft.
In Britain you can be trained on a Huntwing. If you are not the sole owner the instructor will be unable to legally charge. If you are the sole owner he will. In other words it is not possible for an instructor to build a Huntwing and use it for training his students. However in Eire, where the rules have only just started to take shape, there are numerous flyers who have been taught on the Huntwing and the instructors have told me it is an excellent training aircraft. Of course the biggest problem with a non flyer building the aircraft is his total reliance on others to sort out all the test flights etc. This could prove expensive if you are reliant on a flying instructor. Perhaps it would be better to get trained first and then do your own tests.
All the following is HT30TF round tubing. 0.5" x 20g x 4800 10 lengths 0.625 x 17g x 700mm 1" x 20g x 120. 1" x 17g x 4200 1.5 lengths 1 length cut 600 + (1760 to 1900) + 1550 0.5 length cut 1004 +1000 1.125 x 17g x 5000(Bright) Leaves 1 metre spare 1.125 x 13 x 3310 approx. 550 spare (bright) 1.25 x 17 x 290 Bright 1.625 x 17 x 120 1.75 x 17 x 1475 (120,750,625) 1.75 x 18 x 4250 (bright) 1.875 x 17 x 4000 2 x 17 x 4000 2 x 17 x 3500 600 spare 2.125 x 17 x 3550 2 lengths 2.25 x 17 x 4100 2 lengths 2.5 x 10 x 500 2.5 x 17 x 3100 300 spare 2.625 x 17 x 3300 2 lengths The following can be HE30 square tubing. 2" x 2" x 10g x 5000 Bright Contact Hiway light Aircraft for current availability and prices. Details of the metal specifications.
The plans cost £125 within the UK all inclusive and £135 elsewhere to cover the additional cost of Postage. The dollar is approx. 1.4 to the UK pounds.
In the UK send me a cheque for £125 made out to John Hunt, outside the UK a bankers draft for £125 in UK sterling made out to John Hunt.
A set of BMW plans have now been completed, along with complete instructions on the modifications required to the engine and these are available at a cost of £40. The trike plans will be available as a standalone package, both in there original format at a cost of £60 or complete with the BMW plans at £90. This package includes details of the engine mounting frames and also details of the use of the Pegasus Quantum/Quasar tank. If it is intended to use the Blade wing an additional £15 will purchase the owners manual for this combination. The original Huntwing plans are £125 or £160 with the BMW plans attached.
The overall cost is similar to the length of a piece of string. There are so many variables, engine type, use of secondhand parts, amount of work contracted to others. However a rough guide would seem to be approx £6000 with a new 503 and all of the work being performed by you.
Some approx. prices are: the sail is £1100, Tubing £1000, Engine £2000ish, Propeller £350, Minimum Instruments £300, wheels £200, Pod £150, Spats £90 Fuel tank at least £50 and lots and lots of smaller bits and pieces.
A secondhand engine can considerably reduce this cost but be careful !
Built to reasonable quality you can bank on a minimum of 500 hours. This figure will double if you decide to mould your own pod, bend your own battens and make all the material parts, except the sail.
I hope that the above go some way to answering your questions and if you are interested then send for your plans now from.
John Hunt, Old Railway Inn, Clydach sth. NR Abergavenny. Gwent. NP7 0RD UK
01873830876. (Fax Voice) john dot hunt at huntwing dot co dot uk