(original post by neoteric on 22-JUN-2004)

Hovercraft suggestions
My name is Wayne Young and I have been working with the Australian Hovercraft Federation President Ken Osmond on both hovercraft construction at my school Billanook College and promotion of hovercraft construction to schools. I also have extensive involvement in organising and promoting the Australian International Model Solar Vehicle Challenge (being on the state and national committees) which is run around Australia and in other countries. The Discoverhover event looks to be a fabulous project which will engage many students. I have read through the documents and have included some information below which may be of use and some areas that I would like further clarification.

Section 1 - Possible amendments to the instructions and plans
1. Include cutting layout sheets for the most efficient use of both ply and foam.
2. On a photo (bottom hull 2) it shows extra ply and wood pieces ? are these to bolt the top onto? ?There are not drawings for these parts.
3. Licensee page ? reproduced, construction (spelling is incorrect).
4. Engine mount construction ? Point 5 ?with the engine bas(e)?
5. Possible error in the plans(or my reading of them) ? Drawing 65 (is the last section on the left 250mm?).
Drawing 65 shows 2250 mm from the back of the engine post to the front of the craft, however drawing 2 shows 2161 mm from the back of the engine post to the front of the craft, a discrepancy of 89mm.
6. Drawing 6 needs distances to achieve 61 degree cut.
7. Drawing 7+8 need distances to achieve 83.6 degree angle.
8. Drawing 17 needs distances to get top angle
9. Drawing 20, 21 and 30 need distances to get angles.
10. Installing skirt ? 5-15 mph conversion to km/h is not correct Should be 8?24km/h.
- Last paragraph ? change insure to ensure.
11. Thrust duct ? point 1 ?there is no drawing page for this page.
- point 8 ? Part 39 is one piece, but in point 9 it calls for 2 pieces to be stuck together.
- Point 11 ? mentions a hot wire cutter. These are banned in Australian schools because of the fumes produced. Could some safety notes be included in this section.

Section 2 - Questions about the race rules
1. How many drivers?
2. Will there be a skills section?
3. Will there be a speed section?
4. How long?
5. How far?
6. Are boat licences needed in Canberra?
7. Is there a minimum legal age to use the hovercraft in Canberra?
8. What safety equipment must be carried on board to comply with Australian boating regulations?

Section 3 - General questions/issues
1. On the License page it states that only one hovercraft can be built therefore I assume that to build further hovercraft another registration by another teacher would be needed. Is this assumption correct?
2. How much can the craft be modified (eg. provided that the length, width and engine capacity and a cost limit are not exceeded can all other features be altered or do all specifications have to be followed exactly etc.)?
3. Engine issues ? The Tecumseh engines are not available in Australia and the comparable engines are lower in horsepower, heavier and more expensive.
Brand and model Weight lbs Cost $ US Max rpm Max. horsepower
Honda GX340 81-90 : $898.00 3600 9.7
Tecumseh Enduro Rider Engine - - Model #OHV135-206625D Ship Wt. 67.0 lbs $419.99 3600 12.5 HP
Briggs and Stratton 80 - 90 $1000 3600 11

4. The height to the shaft for the other motors (Briggs and Stratton, Honda etc) is vital for the height of the engine which effects the engine mount position. Could alternate designs be done to allow for each of the major brands of motors?
5. Plans ? Could we get a top view and a side view of the hovercraft (It would help with doing designs for the painting)?
6. Safety information is needed on epoxy use (website links and catalogues eg - http://www.westsystem.com/
- a manufacturer of epoxy and products for finishing epoxy , appropriate clothing, breathing apparatus etc).
7. Hull construction - Exterior/marine ply is difficult to get and very expensive in Australia so we have used standard ply except for the engine mount.
8. Body assembly ? Any fibreglass needed?
9. Are there any restrictions on the display of sponsor logos?
10. Why has drawing 2 changed?
11. Can I get written permission to reproduce plans so that the graphic design classes can produce design options for the final painting of the hovercraft? As per licensee page. This is a way of getting more students involved.

Graphic Design Class ? Design brief
The task - A design is needed for a one person hovercraft.
The client - the school (student constructors, coordinating teacher, principal etc)
Design restrictions ? The topside of the craft should be painted with a light colour to prevent heat build-up from the sun. This is especially true of the thrust duct..
Paints must be UV resistant and provide water resistance.
Allow space for the licensee number.
Allow space for race numbers.
Reference materials - Use drawings 4 and 71 and links from http://www.discoverhover.org as a guide.

Section 4 ? Project management

With my class I have placed all the plans into a plastic display book and placed the table below at the front and students have signed up or been assigned responsibilities. They can then move on to their next task easily and the plans are kept in good order. Other teachers may find this useful as a project management tool.
Hovercraft construction responsibilities
Drawing No. Part Material Person Responsible and date required Completed
1 Main deck panel 3 Ply (1/8 ? 3mm)
2 Main deck panel 1 Ply (1/8 ? 3mm)
3 Main deck panel 2 Ply (1/8 ? 3mm)
4 Cockpit (side) (2) Ply (1/8 ? 3mm)
5 Cockpit (top) Ply (1/8 ? 3mm)
6 Engine post Med. density wood
7 Bracket right Mild steel/Alum
8 Bracket left Mild steel/Alum
9 Hull block 2 (right) Foam
10 Hull block 3 (left) Foam
11 Hull block 6 (2) Foam
12 Stiffener Ply (1/8 ? 3mm)
13 Steering stick Conduit or pipe
14 Hull block 5 foam
15 Stringer bottom (2) Low density wood
16 Bracing fin (2) Ply (1/4 ? 6mm)
17 Nose block Low density wood
18 Rudder bridge upper(2) Low density wood
19 Rudder bridge lower(2) Low density wood
20 Stringer top (2) Low density wood
21 Wedge (2) Med. density wood
22 Seat back Ply (1/8 ? 3mm)
23 Skirt attachment front strip (2) Ply (1/4 ? 6mm)
24 Skirt attachment side strip (2) Ply (1/4 ? 6mm)
25 Support (2) Low density wood
26 Air box infill (2) Ply (1/8 ? 3mm)
27 Front infill Ply (1/8 ? 3mm)
28 Skid mount front Ply (1/8 ? 3mm)
29 Skid mount side (2) Ply (1/8 ? 3mm)
30 Skirt mount front Low density wood
31 Skirt mount sides (2) Low density wood
32 Skirt mount rear Low density wood
33 Engine mount Ply (5/8? 16mm)
34 Hull block 1 Foam
35 Hull block 4 Foam
36 Airbox back Ply (1/8 ? 3mm)
37 Airbox top Ply (1/8 ? 3mm)
38 Airbox sides(2) Ply (1/8 ? 3mm)
39 Thrust Duct Foam
40 Rudder tie bar Alum
41 Rudder arm (2) Med. density wood
42 Spacer (2) Plastic
43 Rudder (2) Foam
44 Screen Steel or Alum
45 Propeller Wood as specified
46 Prop Hub Steel or Aluminium
47 Rudder sub assembly
48 Duct assembly
49 Engine mount sub assembly
50 Hull assembly
51 Body assembly
52 Handle Flat nylon
53 Landing skid Alum
54 Front Handle Purchased Alum. handle
55 Hand throttle Alum
56 Steering sub-assembly
57 Steering block Ply (5/8? 16mm)
58 Steering cable As shown
59 Throttle cable As shown
60 Front attachment Alum angle
61 Control assembly
62 Fitting Brass rod
63 Duct Base Ply (1/8 ? 3mm)
64 Skirt corner Coated Nylon
65 Body base Ply (1/8 ? 3mm)
66 Skirt front Coated nylon
67 Skirt side (2) Coated nylon
68 Ferrule Purchased item
69 Skirt rear Coated nylon
70 Hovercraft assembly
71 hovercraft
76 Hinge As shown
98 Pulley As shown
100 Hovercraft assembly
Overall responsibilities
Hull construction ? ______________________________________________
Body subassembly ? ______________________________________________
Engine mount construction ? ______________________________________________
Thrust duct ? ______________________________________________
Air box ? ______________________________________________
Propeller ? ______________________________________________
Rudders and trimming ? ______________________________________________
Hovercraft skirts ? ______________________________________________
Body Assembly/Cockpit ? ______________________________________________
Control Assembly ? ______________________________________________
Thrust duct Assembly ? ______________________________________________
Section 5 - The sheet below could be laminated and placed in a visible position inside the cockpit.

Hovercraft cockpit instructions

Before each engine start/outing check the following parts for security, damage and fatigue cracks.
· engine mounts
· propeller guard
· propeller

After each use
· store the propeller in the horizontal position
· check the hovercraft skirt and screws for damage/looseness and repair.

Skirt filled with water on water
· Use just enough power for a stable hover
· Move forward at a slow pace until the skirt completely drains
Skirt filled with water on land
· Stop hovercraft
· Engine off
· Lift the front of the hovercraft to drain the skirt

Section 6 -
Hovercraft license for students

I intend to produce a test for my students that they need to pass prior to driving the hovercraft. The test will cover information based on the points below (much more detail will be added). If you can send me the information listed in Section A below in Word format I will put together a document and test that I could send back to you so that it could then be used by any teachers.

A. Read the following sections from your manual
1. hull construction ? paragraph 1
2. Propellers ? paragraph 1
3. Propeller maintenance
4. Rudders and trimming
5. Installing the skirt ? paragraphs 4,5+6
6. Skirt repair ? paragraph 1
7. Driving your hovercraft ? All

B. Safety and Environment
? Hearing protection
? Helmet
? Eye protection
? Life Jacket
? Propeller and guard - loose objects etc
? Pilot education
? Environmental issues- The environmental footprint pressure is less than that of a seagull standing on one leg! With such negligible impact,hovercraft have flown over a pedestrian without inflicting harm, and in that respect are possibly the most environmentally safe vehicle in existence.
- wake
? Safety
? Operating area safety ? bystanders/audience
- other craft

Section 7 ? Powerpoint presentation
I produced a powerpoint presentation which Ken Osmond and I used at the Technology Teachers Association Of Victoria Conference. If you are interested in this for teachers or other conferences , let me know and I will send you a zip copy.
Thanks for reading this far,
Wayne Young

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