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HOVERCRAFT FAQ (Frequently Asked Questions)

By: Alex Olshove
V. 1.33

This FAQ will be updated as required and posted to ALT.REC.HOVERCRAFT
at least once a month.  It is meant to be used as general reference by those not familiar with the hovercraft.  If you reproduce this in any way, I only ask that you give me some credit (unless it's bad). :-)

Hovercraft

Contents:

1 This FAQ is completely sucky... how can I make repairs to it?
2 What is a hovercraft?
3 The Skirt
3.1 What's the big deal about the skirt?
3.2 What types of skirts are there?
3.2.1  The bag skirt
3.2.2  The segmented skirt
3.2.3  The juped skirt
3.3  Comparison between skirts.
4  The Engine
4.1  How many engines does a hovercraft need?
4.2  What types of engines can a hovercraft use?
5  Okay, a hovercraft sits on a cushion of air but where does the air
come from?
5.1  How many fans does a hovercraft use? 
5.1.1  Single fan design
5.1.2  Dual fan design
5.2 What types of fans are there?
5.2.1 Axial fans
5.2.1.1 Ducted fans
5.2.1.2 Propellers
5.2.1.3 Propellers vs. Fans
5.2.2 Centrifugal fans
6  How much does a hovercraft cost?
6.1 What are some good sources for buying a hovercraft?
7  Where can I find plans to build a hovercraft?
8  Do you need a pilot license? Driver license? Any US states require
licenses?
9  Are there associations and conventions for hovercraft owners?
Clubs
9.1  Conventions
9.1.1 U.S.A.
9.1.2 France.
10  Are hovercraft allowed on public roadways?
11 What companies manufacture hovercraft?
11.1  Australia
11.2  England
11.3  Canada
11.4  Holland
11.5  U.S.A.
12  Where can I get more information about hovercraft on the
Internet?
13  Can you recommend good hovercraft books to read?
14  Can you make a hovercraft stop and back-up?
14.1  Reversible pitch fan
14.2  Reverse bucket
14.3  Transmission
14.4  Puff ports
15  Can I insure my hovercraft?
16  Aren't hovercraft ‘handicapped’ when it comes to control
(stopping/steering)?
17  Do Hoverboards like in ‘Back to the Future’ really exist?
18  Where the heck to do I find 1/8” marine plywood!?!

1. This FAQ is completely sucky... how can I make repairs to it? Just e-mail me at .  I'm not claiming to be an expert so there may very well be errors in this and I'll be happy to fix them or add more information if you want to set me straight. ;-)

2. What's a hovercraft?

I'm going to answer this question with a description of newer, popular hovercraft.  Perhaps I'll add a history lesson later with descriptions of peripheral jets, etc.

A hovercraft is a vehicle which is suspended upon a cushion of air.  The cushion of air is generated by a fan which is attached to an engine which is attached to the hovercraft.  The cushion of air is contained by a flexible sleeve called a 'skirt' that is attached around the perimeter of the craft to hold the air under the craft and thus upon an air cushion.  The craft is then propelled by whatever means is necessary to carry it forward.  A majority of craft simply utilize a ducted fan or a propeller attached to a small 2 or 4 cycle engine.  Be assured that pretty much every mode of propulsion known to man has already been tried from jet engines to sails.

Control of a hovercraft is accomplished primarily through the use of rudders like the type used on aircraft.  The main difference would be, however, that hovercraft generally utilize many rudders rather than just one.  Another method of control is through 'puff ports' (see 13.1.4) or dual thrust fans where you would slow one down and speed up the other to turn in the direction desired.

3. THE SKIRT

3.1. What's the big deal about the skirt?

The skirt is one of the most important parts of a hovercraft as it is the part that allows the hovercraft to clear obstacles.  Generally speaking, the higher the skirt, the larger the obstacle that the craft will clear.  However, if the skirt is too tall, the craft will 'slide off' the cushion and the cushion will deflate or the craft will become extremely unstable.  This is not a FAQ on hovercraft design so I won't go into this in any more detail.  On larger craft (> 1 or 2 tons) the skirt is made of heavy, rubberized fabric.  On smaller, recreational craft, the skirt is made of neoprene coated nylon that weighs >= 8 oz/sq. yd.

3.2. What types of skirts are there?

There are several types of skirts but the most common are the bag skirt, the segmented skirt, and the jupe skirt.

3.2.1.  The bag skirt:

The bag skirt is basically just that... a bag. The bag skirt should probably be called a tube skirt because it consists of a tube that encircles the perimeter of the craft. The bag is inflated which serves to lift the craft off the ground and more importantly, to contain the air cushion. There are two methods of inflating the bag skirt, the first being serial feed and the second being parallel feed. The serial feed method requires that air be directed from the lift fan _through_ the skirt and then out into the cushion. The parallel feed method requires that a certain amount of air be split off of the lift fan into the skirt (about 10%) and the rest into the cushion.

3.2.2.  The segmented skirt:

The segmented skirt is also called a 'finger' skirt because it consists of several separate nylon segments that, when inflated, press together to form a shape that looks like fingers of a hand that are pressed tightly together (place your hand into a fist and then look at your knuckles). Although much more complex to manufacture than a bag skirt, the segmented skirt offers much less resistance to obstacles and much more ease of repair when damaged since you only need to replace one or two damaged fingers instead of an entire skirt. Segment skirted craft, however, are less stable than bag skirted craft (not necessarily a bad thing if you race hovercraft).

3.2.3.  The juped skirt:

The jupe skirt (a.k.a. cell skirt) consists of several cells that look like cones with their tops cut off and have their bases attached
to the bottom of the craft.  When inflated, these cones readily
support the weight of the craft upon a stable cushion.  A jupe
skirted craft generally utilizes a minimum of 2 or 3 cells surrounded
by a large jupe that encompasses the perimeter of the craft. 
Although a jupe skirted craft is very stable, it will experience
difficulty when attempting to inflate the jupes on a rough terrain
such a tall grass or deep gravel.  Jupe skirts also tend to scoop
water in rough conditions and drag on grass.
 
  3.3. Comparison Between Skirt Type (excerpt from 'Light
Hovercraft Design' by Christopher Fitzgerald and Robert Wilson):

4. THE ENGINE
 
  4.1. How many engines does a hovercraft need?

With the exception of human powered craft, a hovercraft needs at
least one engine.  With a conventional hovercraft, air needs to be
supplied to lift (to make the cushion) and thrust (to propel the
craft).  The supply of air to lift and thrust can be accomplished
using only one engine  by either powering a single fan and then
splitting an amount of air off to lift (about 33%) and the rest for
thrust (called an 'integrated' system) or the one engine can be used
to power separate lift and thrust fans.

Most hovercraft, however, use a dual engine system where one large
engine is used for thrust and another, smaller engine is dedicated to
lift.  Unlike the integrated system, this allows the craft to remain
hovering while the thrust engine is turned off.

Larger, commercial craft may use as many as 6 or 8 engines for power
of the lift and thrust systems.  Engines types range from diesel to
gas turbine.
 
  4.2.  What types of engines can a hovercraft use?

A hovercraft can use (and probably has used) any type of engine you
can think of.  The main point of concern about the engine to be used
is weight.  Obviously a high weight to power ratio is bad for a craft
that is supported by a cushion of air.  Although an air cushion can
support a massive load, that load must still be moved and accelerated
from a dead stop (and then stopped again when need be).  Also, drag
becomes more imminent as the weight of the craft increases.  So, you
must try to keep the engine light and powerful.  Currently, the
engine with the best power to weight ratio is the 2-cycle engine
which is the primary engine used for racing hovercraft. 
Unfortunately these things are _generally_ noisy and temperamental. 
Also, they generally require a gear, belt, or chain reduction system
to match the fan or propeller they are powering.

A large majority of hovercraft utilize the heavier, but quieter, 4-
stroke engines.  Although these engines put out less power than a
similarly sized 2-stroke engine, they are much quieter, don't require
a special fuel-oil mix, and sometimes don't require a gear-down
mechanism.

Large, military or commercial craft will sometimes utilize jet
turbine engines that put out thousands of horse power as well as
large diesel engines.

5. Okay, a hovercraft sits on a cushion of air but where does the
air come from?


The answer is 'fans'.  Fans are a very important part of a hovercraft
whose primary purpose is to inflate the cushion contained within the
skirt beneath the craft as well as to provide thrust with which to
propel the craft forward.  For all intents and purposes, 'fan' in
this text will be used to describe any air moving device.
 
  5.1. How many fans does a hovercraft use?

A hovercraft can use as many fans as the designer wishes.  In fact,
the larger military and commercial hovercraft like the Bell Aerospace
AALC Jeff (B) uses six lift fans and two thrust fans.  In the
recreational hovercrafting world, however, most craft function on two
basic designs. The single fan or the dual fan design.
 
                 5.1.1.  Single fan design

In the single fan design, one engine powers one fan (or propeller). 
Most of the air generated by this single fan is directed rearward as
thrust while a moderate percentage of the air (c. 33%) generated is
split off and thrust below to charge the air cushion contained by the
skirt.
 
   5.1.2.  Dual fan design

In the dual fan design,  one or two engines are used to power two,
separate fans.  One of the fans is dedicated to the generation of air
for the maintenance of the air cushion beneath the craft while the
other is dedicated to the generation of air to provide forward
momentum for the craft.  Typically, this configuration utilizes two
separate engines but occasionally, you will see a system devised
which uses only one engine to power both fans.  This often proves to
be a more daunting task than using two separate engines as the
mechanics involved may become very complex.  After all, you need to
provide a constant speed to the lift fan while allowing the thrust
fan's speed to be moderated. If not, the basic advantage of using two
fans is lost.
 
  5.2.  What types of fans are there?

There are several types of fans that may be used  but the two main
types of fans are axial fans and centrifugal fans.
 
   5.2.1  Axial fans

Axial fans are those that propel air parallel to their axis.  Of the
axial type of fan, there are propellers and ducted fans.
 
                5.2.1.1. Ducted fans

Ducted fans typically utilize several blades that are generally wide
at the tip and  taper towards the base.  A ducted fan may contain as
few as 3 blades and as many as a dozen or more.  These fans need to
be contained within a duct to realize their peak performance.  Some
advantages of ducted fans include the ability to mount reversing
mechanisms such as reverse buckets which direct air forwards when
placed in the column of air generated by the fan.  Also, ducted fans
are generally of a smaller diameter than propellers which can allow
several fans to be placed side by side thus allowing for better
control of the craft (speed one up and slow one down and the craft
turns).  One more major benefit that comes from using fans is that
fans are readily available from ventilation companies.  Ducted fans
can be used to provide either lift or thrust.
 
    5.2.1.2. Propellers

Propellers typically utilize between 2 and 5 blades that are quite a
bit longer than those used on ducted fans.  Although propellers are
generally more efficient (and safe!) when placed in a duct, ducting
is not a necessity as propellers will function well in open air. 
Propellers must be replaced if damaged by debris whereas a blade is
replaceable on a ducted fan.  Propellers are generally noisier than
ducted fans.  Propellers can be used to provide either lift or
thrust.

                   5.2.1.3  Propellers vs. Fans. 

 (Note: This was taken from James Perozzo’s ‘Hovercrafting as a Hobby’ and is best viewed with Courier 10 font.)

  5.2.2.  Centrifugal fans

Centrifugal fans are those that propel air perpendicular to their
axis.  That is, they draw air in the center and 'fling' it out the
side similar to the type used in hair dryers.  This type of fan is
generally limited to use as a lift fan due to their orientation and
relative bulkiness although some craft have been built that use
centrifugal fans exclusively.

6.  How much does a hovercraft cost?

Depends on several factors.  A hovercraft could be build for less
than $300 if you don't mind that it may only support 100 lbs and only
goes 5 MPH.  However, if you need a craft that will support 2 adults
over water at around 30 MPH, then you will probably spend in the
neighborhood of $5000 for a pre-manufactured recreational craft.  If
you can stand something that's used, you can get a good deal for
between $1000 and $5000 for the same craft which will probably get
you a trailer as well.  If you're handy with a saw and screwdriver
then you could build one for less than $1000 or as much as you want
to spend.  All in all, the cost boils down to the materials used to
manufacture the craft (fiberglass or plywood?), the time spent, the
engine(s) (Rotax 503 or B&S 12 HP?), the fan(s), the skirt (bag or
segmented?), and the gadgetry (Radio? electronic actuators?
elevons?).
 
 
  6.1. What are some good sources for buying a hovercraft?

The HoverClub of America's bi-monthly publication called 'The
HoverNews' lists several good deals in the classifieds section in the
back.  Also, there are a few hovercraft related pages on the Web that
have a classifieds section.  You can also order a brochure directly
from the manufacturers listed below.

Recreational hovercrafting Have fun riding on a cushion of air ... Visit my site for fun and profit! usahovercraft.com

7. Where can I find plans for building a hovercraft?

Why not design your own?  If you're not feeling that confident, then
try the dealers listed below:

Sevtec Inc.
PO Box 846
Monroe, WA  98272.
794-7505
sevtec@aol.com
Models:
Scout  ($29)
Vanguard ($44)
Prospector ($48)
Explorer ($62)
Mariner ($92)
http://members.aol.com/sevtec/sev/skmr.html

Universal Hovercraft
3rd Street Box #281w
Cordova, IL 61242
Phone / Fax (309) 654-2588
Complete Catalog $2.00
Too many plans to list
http://www.hovercraft.com

Databoat International, LTD.
PO Box 1073, 8609 Fissile Lane
Whistler, BC Canada V0N 1B0
databoat@whistler.net
Models:
Neoteric Neova 4 ($143.50)
http://www.databoat.com/27hover.htp

Robert Q. Riley Enterprises
Box 12294
Scottsdale, AZ   85267-2294
Phone: (602) 951-9407
rqriley@netzone.com
Models:
Tri Flyer ($45)
Pegasus ($35)
http://www.netzone.com/~rqriley/plans.html

8. Do you need a pilot license? Driver license? Any US states
require licenses?

Most vehicles are required to be insured (whether as a boat or an off-road vehicle, or both).  About hovercraft regulations

9. Are there associations and conventions for hovercraft owners?

Yes, here is a list of Clubs followed by some annual conventions.
 
  9.1.  Clubs

Australian Hovercraft Federation
Michael Nell
17 Fegen St.,
Huskisson, NSW 2540, Australia
Email: nell@mpx.com.au
Title of Publication: Australian Hovercraft News
Frequency of Distrbiution: Quarterly
Cost of subscription: Australia AUS$20.00; USA US$25.00
Contact: Tim pryor, Editor, Australian Hovercraft News [tpryor@mail.fairfax.com.au].
38 Barnes Road, Frenchs Forest, New South Wales 2086, Australia

Hovercraft Club of Canada
10 Gold Crescent
Russell, Ontario
CANADA K4R 1B4
Tel / Fax: (613) 445-3139
Bob Rennick
Title of publication: 'Hovercraft Club of Canada Newsletter'
Frequency of distribution: Four times a year
Cost of subscription: Membership in the club ($15/yr)
http://www.peaceregion.com/hover/


Hoverclub of America
PO Box 908
Foley, AL  36536-0908
Phone: (334) 943-3279
Title of publication:  'HoverNews'
Frequency of distribution: Every two months
Cost of subscription: Membership in the club ($30/yr).
Http://www.hoverclubofamerica.org/


Hoverclub of South Africa
5 Marais Street
Somerset West 7130
SOUTH AFRICA
Title of publication:
Frequency of distribution:
Cost of subscription:


Belgian Hoverclub
Blvd St. Michel 78 1040
Brussels
BELGIUM
Title of publication:
Frequency of distribution:
Cost of subscription:

RHONE ALPES AEROGLISSEURS
Jean CLAUDE DELORME
RUE DU MONT CINDRE ST
CYR AU MONT D'OR
FRANCE
Title of publication:  "POTIN d'AEROS"
Frequency of distribution: bi-monthly (once every two months)
Cost of subscription: 12 (Francs?)

Hoverclub von Deutschland
Lechfeld Str. 2
Mering
GERMANY
Title of publication:
Frequency of distribution:
Cost of subscription:

Hoverclub of Great Britain
Secretary: Mrs Brenda Kemp
Long Acre, Bingham, Notts, NG13 8BG
Title of publication:  Light Hovercraft
Frequency of distribution:
Cost of subscription:
Editorial contact: Jeremy Kemp
Long Acre, Bingham,
Nottingham, NG13 8BG

The Netherlands Hovercraft Club
Uiterdijksehof 5,
JK Nederhorst den Berg
HOLLAND
Title of publication: Hovercraft Sportnieuws
Frequency of distribution:
Cost of subscription:

Japanese Hovercraft Association
C/o SOREX Co. Ltd.
KOUMENAKA
Kumenan-cho, Kume-Gun
OKAYAMA-KEN, 709-36
Title of publication:
Frequency of distribution:
Cost of subscription:

Hovercraft Club of New Zealand
David Van Bysterveldt
Robinson Rd,
4, Paeroa
Phone 64-7-862-4793
NEW ZEALAND
Title of publication: Hover News
Frequency of distribution:
Cost of subscription:

Wellington and Wairarapa (New Zealand) Hover Club
Kerry Workman
Harvard Grove
Totara Park
Wellington.
New Zealand
Phone: (04) 5267655
http://www.voyager.co.nz/~arthurg/
arthurg@voyager.co.nz

Swedish Hoverclub
Ollonvaegen 17
Akersberga
SWEDEN
Title of publication: Hover News
Frequency of distribution:
Cost of subscription:
 

       9.2. Annual Events

There are many annual events around the world.  Here are some of them
listed by country.  For more specific information, visit
http://www.hoverclubofamerica.org/content.aspx?page_id=2&club_id=831743 courtesy of the
Hoverclub of America.
 
    9.2.1. U.S.A.

What: West Coast Hover-In and Cruise
When: July
Where: Long View, Washington

What: The U.S. National Cruise on the Wisconsin River
When: August
Where: Muscoda, Wisconsin

What: Scioto River Hover-In & Cruise
When: August
Where: Chillicothe, Ohio

What: Tennessee Hover-in
When: October
Where: Big Spring, Tennessee

What: Texas Hover-In
When: October
Where: Dallas/Ft.Worth Texas

What: 23rd National Annual Hoverally
When: June 12,13, & 14, 1998
Where: Troy, Ohio
 
 
    9.2.2.  France

What: The World Hovercraft Championship
When: August
Where: Luçon in the Vendée, France
 

10. Are hovercraft allowed on public roadways?

Nope.  And you probably wouldn't get very far if they were since most
roads are 'humped' up in the middle to allow for water run-off. 
Unfortunately, this also causes air cushion vehicles to slide off to
the side of the road since there is no friction to hold 'em on there. 
If you're a skilled driver, then you can counteract the sliding
affect by directing the nose of the craft towards the center of the
road and 'crab' sideways like you would during heavy wind. 
 

11. What companies manufacture hovercraft?

The companies listed below are categorized by country.
 
  11.1.  Australia

Airlift Supercraft (Aust) Pty.Ltd.
Olsen Avenue
ASHMORE, 4214
Queensland
Australia
Phone: Australia 07 5527 8111
Fax: Australia 07 5527 8016
Models:
AS 400 Thriller
AS 560 Hoverflyer
AS 560U HoverUte
AS 600C Mustang
AS 600A Mustang Ambulance
AS 8900 Pioneer
AS 10600 Pioneer L(ong)
AS 1200 Challenger

TURBO Hovercraft Pty. Ltd.
Vortex Hovercraft Pty. Ltd.
Models:
Turbo 235 Superwedge
225 Wedge
Vortex 245
Turbo 265 Super
Turbo 265 Hyper
Rocket

Revolutionary Technology
11 Mulberry Court
Eltham
Victoria, Australia, 3095
(Owen Ellis designer of Rocket)
Models:
Rocket (seen by many at the last world championships)

 
  11.2. England

Pegasus Aviation
Elm Tree Park
Manton, Marlborough, Wiltshire, SN8 1PS
ENGLAND, UK.
Tel. + 44 (0)1672 861578
FAX. + 44 (0)1672 861550
pegasus@cccp.net
Models:
Cyclone PRIMO
http://ayla.avnet.co.uk:80/pegasus/caprimo.htm#primo

Bill Baker Vehicles

Eagle Hovercraft

Ingles Hovercraft Associates Ltd.
Ingles Manor
Castle Hill Avenue
Folkestone, Kent CT20 2TN
ENGLAND, UK
Models:
River Rover
 
 
  11.3. Canada

AeroTour Canada
1279 boul. Hurtubise
Gatineau, Quebec, J8P 7C2
Tel.: (613) 762-3167
Voice and fax: (819) 669-8454
http://www.angelfire.com/biz/aerotour


Canair Hovercraft Inc.
O. Box 478
Carleton Place, Ontario
K7C 3P5
Telephone: (613) 257-8332
Facsimile: (613) 257-7948
Models:
Canair 504L
http://local40.pr.incentre.net/~hover/canair.htm


Surface Effect Boats (S.E.B.) Enterprises Inc.
Models:
AirCat 7
 
  11.4.  Holland

Hovertrans B.V.
Keizersveer 9
LD HANK
The Netherlands
Telephone: +31 1622-3062
Tel/Fax: +31 1622-3075
hovertrans@pi.net
Models:
Colibri
Hurricane

HP Design
Uiterdijksehof 5
JK Nederhorst den Berg
NETHERLANDS
Models:
Sprinter
 
     11.5.  U.S.A.

Hovercraft America
N114 W18605 Clinton Dr.
Germantown, WI 52033
Phone: 414.253.9979
FAX: 414.253.9033
hover@execpc.com
Models:
HA-5
http://www.execpc.com/~hover/index.html

Hovercraft Concepts
13910 SW 139 Court
Miami, FL 33186
305/256-8696
FAX: 305/256-8698
Contact: William Flett
Models:
SA 580
Aerocruiser SA 1100 (price: $12,995)

HoverDynamics
JAKenney@aol.com
Models:
Starcraft RX2000

GPL Enterprises
Contact: Gary Lutke
Tangelo Terrace #A13
Delray Beach, FL 33444
Phone: (407) 274-2247 or (800) 541-7228
Fax: (407) 276-4159
Models:
Air Commander

Neoteric Hovercraft Inc.
Tippecanoe Street, Dept.. 12
Terre Haute, IN  47807-2394
Telephone: (800) 285-3761
Alternate Phone: (812) 234-3217
Fax Phone: (812) 234-3217
Hovercraft@delphi.com
http://www.sapphire.com/UNCAT/uncat135.html

Oregon Hovercraft
27612 Crow Rd.
Eugene, OR 97402
Telephone: (541) 485-0588
hiblerp@continet.com
http://www.continet.com/hovercraft/

Sevtec Inc.
PO Box 846
Monroe, WA  98272.
sevtec@aol.com
Models:
Scout
Vanguard
Prospector
Explorer
Mariner
http://members.aol.com/sevtec/sev/skmr.html

Hovertechnics Inc
Contact: Hugh B. Firminger
Box 257
St. Joseph, MI 49085
Phone:(616) 925-0025
Fax: (616) 925-6940
Models:
HoverJet

Weber Hovercrafts
28728 Crabtree Corner Road
Cuba City WI 53807
vweber@mhtc.net
Phone: (608) 744-3678: Verdon
Fax: (608) 759-5704: Vernon
Models:
StarCruiser 1-4
Price: $3400 +

SCAT Hovercraft of Washington
PO Box 4838
Federal Way, WA  98063
voice (206) 838-5005 or (888) NEW-SCAT

New Mexico Scat
P O Box 90575
Albuquerque  NM  87199
Dan Morris
Phone: 505-828-2273

St. Louis Hovercraft Rides Inc.
P.O. Box 73
Chesterfield, MO  63006
Michael Murphy (MURHOVER@aol.com)
Models:

HoverStar
HoverJet
http://members.aol.com/MURHOVER/index.html
 

12. Where can I get more information about hovercraft on the
Internet?

When I first started the Hovercraft Homepage, there was no, none,
zip, zero, nada information about hovercraft on the Internet.  Now
there are hundreds of web pages to access.  If you're too lazy to do
an Alta Vista search, here are what I consider to be the main pages:

http://www.olshove.com/HoverHome My Hovercraft Homepage.

http://www.hovercraftersresource.com/  Kelly Jernigan's Hovercraft Resource.

http://members.aol.com/sevtec/sev/skmr.html Barry Palmer's Sevtec
page.

http://www.hoverclubofamerica.org/ The HoverClub of America's
Official Homepage.

http://www- personal.umich.edu/~untitled/hover.html HoverTechnic's
Page.

http://www.ozemail.com.au/~ahf/index.html The Australian Hovercraft
Federation Page.

http://www.ils.nwu.edu/~eric/hover.html Eric Goldstein's page.

http://www.innotts.co.uk/~pault/hcgb.htm The Hoverclub of Great
Britain Homepage.

http://www.hovercraft.com  Universal Hovercraft.

http://www.peaceregion.com/hover/ The Hovercraft Club of Canada
Homepage.

There is now one newsgroup relating to hovercraft called
alt.rec.hovercraft.  If you don't see it on your local news server
then please e-mail root@ (root@xoom.com or root@netcom.com,
etc) and request that they start carrying alt.rec.hovercraft on your
news server.

An easy way to read and post to alt.rec.hovercraft is through a
service called DejaNews.  You can get to this service via your web
browser by entering http://www.dejanews.com as the location.  When
you get there, you can simply enter ‘alt.rec.hovercraft’ in the edit
box marked ‘Type a specific question or topic:’.

I have the capability to start a mailing list but I want to see how
the news group does for awhile before I consider maintaining such a
pain in the hoo-ha.
 

13. Can you recommend good hovercraft books to read?

Sure thing.  In fact, these were the primary sources for this FAQ
(other than from my noggin that is). ;-)

Title:  Hovercrafting As a Hobby
Author: James Perozzo
Subject:  All aspects of hovercraft design for recreational use.
Available From: Twin Peaks Publishing; 30455 Kent-Blk Diamond Rd.,
Auburn, WA 98092. (253) 631-7347.
NOTE: The author has passed away and this book is out of print.  If
you can get a copy, it’s a good book for beginner to intermediate.

Title:  Jane's Surface Skimmers
Author: Jane's USA
Subject:  General hovercraft reference.  Lists darn near everything
ever built.
Available From: http://www.janes.com/.
Your best bet for getting your hands on one of these rather expensive
references is to search for a used one through a book exchange.

Title:  Light Hovercraft Design
Author(s): Christopher Fitzgerald and Robert Wilson
Subject:  General hovercraft design reference.
Available From: The Hoverclub of America.  See above for contact
information.
 
14. Can you make a hovercraft stop and back-up?

Yes, although it requires some mechanical wizardry since no part of
the craft is in contact with the ground.  This is generally
accomplished via reversible pitch fan, 'reverse bucket',
transmission, or 'puff ports'.
 
  14.1.  Reversible pitch fan

A reversible pitch fan (or propeller) is a fan that allows the
operator to physically reverse the pitch of the fan blades thus
reversing the flow of air forward thus slowing and/or reversing the
direction of the craft.  These are mechanically complex and are not
useful in a craft of single fan design (see 4.1.1.a) since the
reversing of the airflow would essentially create a vacuum in the
cushion and suck the craft to the ground.
 
  14.2.  Reverse bucket

A reverse bucket is placed, mechanically, directly rearward of the
thrust fan to redirect it's airflow forward via a curved surface when
the operator wishes to slow the craft or stop.  Although this method
is much simpler than a reversible pitch fan, the bucket adds weight
to the rear of the craft in addition to the engine, duct, fan, and
rudders.  Also, reverse buckets are only useful with smaller diameter
fans.
 
  14.3.  Transmission

A transmission is sometimes as complex a solution as a reversible
pitch fan.  As in an automobile, a transmission reverses the rotation
of the fan and is attached to the driveline between then engine and
the fan.  A transmission may utilize gears as in an automobile or
belts as in a 'mule drive'.
 
  14.4.  Puff ports

Puff ports are apertures through which air is redirected from the
lift or thrust system to the front or sides of a hovercraft.  When a
puff port is opened, the air is allowed to flow out of the craft in
whatever direction the operator desires.  Realistically, puff ports
are only useful at slow speeds since they often lack the ability to
pass air at a sufficient velocity to counteract a craft with much
momentum and are used primarily for low speed maneuvering.
 

15.  Can I insure my hovercraft?

Currently, insurance for hovercrafts is very difficult to obtain (in
the USA anyway).  Most insurance companies don't even know what a
hovercraft is but may insure your craft as a boat
 

16.  Aren't hovercraft  ‘handicapped’ when it comes to control
(stopping/steering)?


Nope, we prefer to see those as "limitations of frictionless motion". 
It could as easily be said that automobiles suffer from the handicap
of not being able to move over water or that boats suffer the
handicap of not being able to transition to land travel.  The primary
advantage of the hovercraft is that you can fly them over any
relatively flat surface on land, snow, mud, water, swamp, peat bog,
river, etc.  They are being used more and more often for rescues,
ferrys, and general grins (_big_ grins).

Advances are gradually being made in control.  We've learned, for
instance, that a tighter, more controlled turn at speed can be made
by tilting the hovercraft to one side and banking it through a turn.
This can be accomplished by operator weight shift, elevons, or
cushion control mechanisms.  The resulting control starts to approach
that of your average speed boat on full plane and exceeds that of
your basic automobile on an icy highway. ;-)

Braking is accomplished fairly effectively through the use of thrust
reversing mechanisms such as reversible pitch propellers, and reverse
buckets.

True, hovercraft don't offer the best response times for braking and
steering as water plows (boats) and automobiles but owners/operators
of hovercraft would agree that the advantages of hovercraft travel
outweigh the disadvantages which, by the way, are adjusted to as the
operator gains experience.


17. Do Hoverboards like in ‘Back to the Future’ really exist?

Figure it this way.  An axial fan puts out only so much lift
per horsepower.  In hovercraft terms this is measured in pounds per
square foot.  A good lift system will produce 10 lbs per sq. ft. 
Multiply the the area of the hovercraft by the lbs-sq-ft for a rough
idea if it will work or not.  How big is the hoverboard?  1' x 4' ? 
That is 4 square feet.  With a good lift system you will have 40 lbs
of lift total.  Now, how much do you weigh?

Note:  This explanation was graciously provided by Dave Galka who is
the editor of HoverNews for the Hovercraft Club of America.  In
summary, a 1’ x 4’ board is capable of supporting about 40 lbs. 
Unfortunately, most humans weigh much more than this.  Sorry, but
hoverboards will not be a possibility unless a seriously powerful
power source can be devised.  Preferably one that can supply at least
40 lbs per square foot and still fit within the confines of 1’ x 4’.

18. Where the heck to do I find 1/8” marine plywood!?!

Okoume is a fairly common mahogany 3-ply marine plywood available
from numerous sources. It is light, bends easily and is moderately
durable.  Below are some suppliers:

M.L. Condon Co., Inc.
260 Ferris Ave.
White Plains, NY  10603
914- 946-4111
914-946-3779 (fax)
Marine grade okoume - 3 mil, 4x8 $40 / sheet

Edensaw Woods, Ltd.
800-745-3336
PortTownsend, WA
www.olympus.net/edensaw/
Marine grade okoume - 3 mil, 4x8 $37 / sheet

Boulter Plywood Corp.
24 Broadway, Dept WB
Somerville, MA  02145
617-666-1340
617-666-8956 (fax)
Marine grade okoume - 3 mil, 4x8 $39 / sheet

Harbor Supply
1401 Russell Street
Baltimore, MD  21230
800-345-1712
410-752-0739 (fax)
Exterior grade okoume - 3 mil, 4x8 $24.68 / sheet
Marine grade okoume - 3 mil 4x8 $53.20 / sheet

 

 

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