Go to the end of this page for links to F1, F3 and FJ craft construction photos.

21/04/03

We are very late in preparing the craft this year. We were going to renew the hull but simply ran out of time. Changes this year to last years craft are;

1)       Revised skirt design. Skirt angle again reduced and the angle of the pressure piece in the segments revised.

2)       New Lift Engine, we are experimenting with an engine developed for paragliding. Wieght and power output compared to the Rotax we have been using are favourable. Reliability is a completely unknown question at this time, water proofing may well be an issue.

3)       Thrust engine 17mm lower

4)       Revised exhaust. Some improvements in power output obtained.

5)       Thrust fan tip speed increased.  We have hitherto been running a very conservative pulley ratio gearing. This has been changed to the maximum allowed by the regulations.

6)       Some detail changes such as different fuel pump, carburettor air filter design and instrumentation.

Not all these changes may be available for the first race meeting.

Testing 20/04/02

OK, so how fast to sixty mph (100kph) is our new hovercraft? GPS equipment is too slow to measure it. Ken who also owns a microlight reckons that a decent microlight accelerates as fast as a Porsche. Testing at a microlight airstrip we were comfortably faster than that and I was having to shut off power after 5-6 seconds having covered more than half the runway length. Videos\0-60 mph.wmv We need to "con" our local Police in to using their speed trap equipment..... we are working on it.

We have hit a snag with the addition of an elevator. During test runs down a slightly bumpy microlight airstrip at full power, neither Ken nor I were able to take our hands of the handlebars to use it!!

The new geometry pressure bag skirts do make the craft feel less "bouncy" and laterally more damped.... but blasting up and down an airstrip wasn't a good test. The cushion, skirt and hull pressures were interesting though.

Other than a small piece of re-enforcing required on the lift engine silencer we are ready for the 2002 season.........

The new craft for 2002 is a development of the Mirage that came third in last years Championship. Changes include -

Reduction in weight. Last year we used chopped strand mat to construct the craft - simple and easy to work with. Now that we have gained experience with the craft and know the areas that can be lighter and the others that needed strengthening we have switched to construction using woven matting. The basic hull without machinery will be at least 10% lighter.

Revised skirts. The pressure bag skirts will be less tightly sewn to produce an increase in effective width by two inches per side. Quite apart from making the craft effectively 4 inches wider the different skirt construction will reduce the cushion pressure and possible back pressure problems on transitions affecting the lift engine (see 2001 Bilcombes Lake report).

Fitting of an elevator.

Lift engine changes. Last year our first choice of lift fan blades were not available. We had to make do with fixed pitch affairs. We tried several designs during the year but were never really happy with the lift engine setup. Fortunately the variable blades are back in production and we can revert to a tried system.

And as you can see - a different colour scheme - Purple with Yellow duct and side flashes.

The hull is made, just the skirt to deal with. Testing will be a last minute affair - 20th April 2002 at Tattershall.

Mirage Rotax F1 hull # 1244

Eagle TZR250 MkII F3 hull # 1127

Eagle RD250 MkI FJ hull # 695