Hovercraft speed record

[Fex2005]

Just reading the Guinness book of records while in the bath (as you do), and came across the speed record for a Hovercraft. Apparently only 72mph?

How is this so slow, surely it wouldn't be hard to beat this (big V8 and massive Fan?).

Edited by Fex2005 on Saturday 12th September 20:07

[Adrian Swarl]

Perhaps the eels slowed it down?

[Caruso]

Adrian Swarl said:

Perhaps the eels slowed it down?

Have a

Does sound like an easy record to beat, unless there's some inherent limiting factor to hovercraft speeds like there is with helicopters?

[OnTheOverrun]

Your book is wrong. Even the old cross channel hovercraft could do 83 knots. That's nearly 96mph for you land-lubbers.

[agric]

Doesn't seem very quick considering the size of the motors & the fact its 'airborne'

Perhaps calculations with a scale model/conveyor belt


What say you Eric?

[Fex2005]

OnTheOverrun said:

Your book is wrong. Even the old cross channel hovercraft could do 83 knots. That's nearly 96mph for you land-lubbers.

From www.hovercraft.org.uk:

SRN4's attained a higher speed during cross-channel operations but I've never had this confirmed (and it was never verified by an 'official' organisation). I've also read that an American experimental sidewall hovercraft, powered by water-jets exceeded 100-mph - also never confirmed.

The www.world-hovercraft-federation.org guidelines for the speed record also limit the noise to 87db which probably ruled the SRN4s out.

So to get my name in the 'big book' I only have to beat 82mph apparently?

Edited by Fex2005 on Saturday 12th September 20:44

[OnTheOverrun]

No, you have to beat the 85.87mph achieved on September 18th 1995 by Bob Windt.

[spikeyhead]

I think I may have jsut found something to stop me getting bored in the Netherlands.

The winter project, rustle up a hovercraft design.

[SimonV8ster]

Adrian Swarl said:

Perhaps the eels slowed it down?

What ? Somebody else has found it hilariously funny but i've missed it obviously. I hate not understanding jokes.

[Adrian Swarl]

SimonV8ster said:

Adrian Swarl said:

Perhaps the eels slowed it down?

What ? Somebody else has found it hilariously funny but i've missed it obviously. I hate not understanding jokes.

http://www.youtube.com/watch?v=2YYM209GJoE

[Simpo Two]

Surely replacing propellers with jets would make a difference...?

[GreenV8S]

agric said:

Doesn't seem very quick considering the size of the motors & the fact its 'airborne'

Momentum drag is a big problem with hovercraft. There's a heck of a lot of air blown through the air cushion, and it all has to be accelerated up to the speed of the hovercraft so the power requirements go up very sharply as the speed goes up.

[Chrisgr31]

The other issue with hovercraft is the fact that you need to keep them relatively near the gound, and avoid them flipping over!

It is worth going along to a hovercraft race if they are in your area to see the craft in action, it can get very hairy especially in the F1 class where the 0-60 speeds are estimated to be around 6 seconds. When they go over they tend to go very quickly, see this clip http://www.metacafe.com/watch/1964673/extreme_hove... which was filmed at Claydon. At Claydon they had the air ambulkance out 2 years in a row! The third year they had a collection for the air ambulance but didn't need it! Did need a land ambulance though!

[RizzoTheRat]

Chrisgr31 said:

The other issue with hovercraft is the fact that you need to keep them relatively near the gound, and avoid them flipping over!

There's some novel ideas to get around that one though. There's an American company that sell a homebuild kit hovercraft that has detatchable stub wings, above about 70mph it flies as a wing in ground effect.

[Sixpackpert]

GreenV8S said:

agric said:

Doesn't seem very quick considering the size of the motors & the fact its 'airborne'

Momentum drag is a big problem with hovercraft. There's a heck of a lot of air blown through the air cushion, and it all has to be accelerated up to the speed of the hovercraft so the power requirements go up very sharply as the speed goes up.

Nope. The cushion is actually very low pressure and with a seperate lift fan there is no problem.

The main problem with 1-2 seat racing hovercraft is that they are inherently unstable. The latest hull design for formula 1 and 2 is very pointy so reducing the frontal area of the craft. This helps to reduce lift at speed and increase stability when cornering.

You also do not necessarily need a large engine for high speeds. One craft I use has a 90hp BMW K100 engine for thrust and will sit quite happily doing 65mph. Another craft that only has a Briggs & Stratton 22hp thrust engine will also do 60 mph quite happily, it just takes longer to get there.

Being able to stop a craft flying when at speed is the key. Also the speed run is done in two directions. One direction could be down-wind, causing the craft to plough-in (this is when the front skirts collapse and the craft stops very very quickly!) the other direction could be up-wind so causing the craft to lift and flip.

Here is an example of a headwind causing a 'bit of an issue.'

Edited by Sixpackpert on Tuesday 29th September 10:05

[dirty boy]

Did you know the Hovercraft was invented just down the road from me.

Useless infomation huh?

Somerleyton.

Anyway, as you were.

http://www.hovercraftsomerleyton.org.uk/index.htm