Design update by 4wings Hovercraft development May 1999

- May update -

To all passing by at our pages, lot of thanks, and to all sending in some info even more thanks from us as well as all the Hovercraft interested surfer. The main part of our update is from Ross McLeod - Airlift Australia with his designs. I saw his crafts a few years ago on hunter.net which disappeared from the www. So lets give these nice designs a new home where we can all appreciate the sweeping lines of the design.
Besides we post some info on differentially acting "Elevons" which might be for some of us quite interesting.
All the credit goes to MAF Hovercraft's. Follow-up on Hovercraft construction requirements and regulations from Canada which made the long way via snail mail to S-Texas.
Last not least I want to remind you all to sign up for our list server to get informed about future update like this.
Lot of thanks
Michael

Hovercraft Ranger by Ross Mc.Loud - Airlift Hovercraft

Ross McLeod - Airlift Hovercraft Australia -

designed some of the commercial crafts you might see in Australia, Hong Kong, Malaysia and other parts of this globe. His crafts are designed after existing regulations - ( British Loyd's / USCG / HCGB / Au. ...) which gives the future owner the possibility to use the craft on a commercial basis with prepared paperwork. Something you should hold in mind before you commission a craft for smooth operation. As well as none of his craft have had structural failures.
His craft's range from the 6 Person Hover flyer to the 25 Person craft seen in a later update. We feature in this update the Hover flyer and will post the other designs with time passing by.

The Hoverflyer

General Specification The HoverFlyer is a fully amphibious hovercraft that has been well proven and manufactured since 1989. It has provided many thousands of hours of enjoyment and income for commercial owners carrying many thousands of joy riders. Private owners too are enjoying the benefits of the HoverFlyer with uses as diverse as yacht tender to accessing fishing, diving, holiday house access and hunting. Technical Details

Length : 5.60 meters
Width   : 2.35 meters
Cockpit length : 2.8 meters
Cockpit width   : 1.5 meters
Cushion height : 350 mm front, 320 mm rear
Accommodation : 5 Passengers
Payload   :   500 kg
Empty weight : 670 kg
Lift engine Briggs & Stratton Vee Twin, OHV, air-cooled, 16 h.p.
Thrust engine Subaru flat 4 cyl, OHV, water-cooled
Fuel consumption 9.7 liters per hour (cruise) average Fuel capacity60 liters

For more detailed info please see our Guest page.

An Integrated System of Control For Hovercraft
Using Differentially Acting “Elevons”
T. J. R. LONGLEY
by
T Eng(CEI) AMRAeS
Chief Designer, MAF Hovercraft Introduction
The design of the “River Rover” light Utility hovercraft posed a number of stringent demands. The most exact-ing was without doubt the requirement that the craft should possess the ability to negotiate sharp bends in rivers with the least possible sideways skidding.
Hitherto, most light hovercraft have relied on vertically hinged rudders or vanes to achieve directional control. With undesirable “side effects” of such systems . Suffice it to say here that, as a result, lack of really positive control is a feature which has to a large extent become accepted as inevitable.
On larger commercial craft where more precise control is a requirement, this is only achieved at considerable expense and complication. Various systems, such as skirt shift or skirt lift, “puff-ports”, and pivoting Propeller pylons are employed. Sometimes a combination of all three systems may be found on one craft.
The “elevon” system of control not only combines the functions of these systems in one extremely simple system, but with little extra complica-tion it can also provide longitudinal pitch control, and thrust control over a full range from full forward thrust, through zero, to full reverse thrust. This feature makes the elevon system readily adaptable to hovercraft using the simplest of integrated lift and propulsion systems (i.e., one where the engine is permanently engaged to both lift and propulsion fans). The “River Rover” embodies such an integrated System and, together with its elevon controls, results in a hovercraft which is of extremely simple construction, but which is easy to drive and very maneuverable.

The Effect of the Elevon System on Directional Control

In its simplest form, an elevon can be considered as a pressure balanced butterfly valve hinged horizontally across the efflux of a propulsion fan duct. These ducts are mounted in pairs, each one being positioned either side of the craft center line, as far outboard as practicable. A single engine drives both fans via belts and pulleys. The elevons are rigged so that, in the neutral Position, both lie
horizontal, thus presenting the least possible resistance to rearward thrust.
A joystick type control column in the cabin is used to effect differential movement of the elevons. Lateral dis-placement of the control column causes the trailing edge of one elevon to move downwards through a relatively small angle (up to 13° on the River Rover). The trail-ing
edge of the other elevon can be moved upwards through a greater angle, until the vertical position is
reached. In this position it shuts off all rearward flow from the duct. The combined action of the two elevons is therefore as follows:
Small sideways movements of the control column impart small positive incidence angles to one elevon, and small negative angles to the other.
This action is analogous to the Operation of ailerons on an aircraft, causing the craft to bank into the desired direction of turn. Further, coarser, sideways movement of the control column progressively increases the negative incidence of the upgoing elevon, thus increasingly restricting the rear-ward
efflux from the fan on that side. On the other side, the elevon retains its small positive incidence angle, with little reduction in thrust. The resultant differential thrust combines with the bank into the turn to cause the craft to yaw in the desired direction.

- Follow up on construction requirements -

For our friends in Canada :
"The current construction standards for Canadian air cushion vehicles (hovercraft) are contained within Transport Canada's publication TP5579. "Design, Construction and Operational Safety of Dynamically Supported Craft in Canada - Air Cushion Vehicles".

TP5579 is not available on the Web at this time, here is an on the Web where some of the Canadian TPs are available: http://www.tc.gc.ca/shipsa~1/toc_e.htm
If other persons are interested in getting copies of TPs that are not available on the Web they can E-mail, phone or right to me to get a copy, because they are not available anywhere else.
Thanks
Lise Charron
AMSB
(613) 991-3135"
If your craft is below 1.000 kg payload you don't need them - just try to work after HCGB construction requirements.

For our friends in Great Britain :
"At present the WHF and EHF are really only concerned with racing craft. The British Club, the Hovercraft Club of Great Britain have construction regulations for bigger cruising craft.

Category Two craft are for those which are used in protected environments and Cat 3 for independent use. Cat 2 regs are available, Cat 3 are being drawn up.

The major problem is that in Britain we are limited to craft of a maximum unlaiden weight of 1000 kg. After that the craft must be registered with our Marine Safety Agency - and that is very expensive!

Commercial craft are built to a separate set of regulations set down by the British Government Agency.

Jim"

You can get the available literature from the HCGB at this URL : http://www.hovercraft.org.uk/publications.htm#Top

This was the may update - we hope you found something interesting and see you soon at 4wings Hovercraft development