Building with Craft Foamboard

[Paul TParticipant @pault84577]

Ashley: The tanks will be set up for fresh water (tap water) filling after the model is launched, the water will be pumped in from a storage container and after sailing pumped back out again. I want to avoid using lake water as it tends to leave a smell in the tanks.

The tanks wont need anti slosh plates as they will be filled.

Kim: I have been toying with making some kind of launching trolley with attached crane winch because as Ashley says I am well past my sell by date.

Ian: Sorry to say that I don't know what the final displacement will be as I am still playing around with the design.

Not feeling so hot today

Paul

[Paul TParticipant @pault84577]

Having been laid up with plenty of time to think I am now convinced that laminated foamboard would be an excellent material for building model hovercraft.

I have been looking at Mark Porters plans for his Griffon 2000td and think that foamboard would make an excellent substitute for plywood.

[LARRY WHETTONParticipant @larrywhetton68737]

Hello Paul,

Nice to see back on the forum, hope you are feeling better now

and getting the old little gray cells active , but take it easy now cheers Larry….

[Paul TParticipant @pault84577]

Hello Larry

You know what its like …once a builder always a builder…you just have to be active and it doesn't matter if its a huge site or a simple model because you fear that if you stop then you will never start again.

Take care

Paul

[Ian GardnerParticipant @iangardner62867]

Welcome back Paul,

I shall watch with interest if you do decide to have a go at the Griffon hovercraft.

A while back our club lost its water and I thought I might be forced to use a stretch which is notoriously weedy in summer- so my thoughts turned to hovercraft and I researched the Griffon 2000- even downloaded the drawings and bought a DVD!

Luckily the club has found a new water but there still remains a spark of interest in these fascinating craft.

I used to use foamboard a lot when I worked as a framer, and I can see the potential, clean and easily worked. Wood dust seems to affect me more these days as well.

Stay well!

Ian

Edited By Ian Gardner on 09/04/2013 09:02:14

[Trevor HollowayParticipant @trevorholloway99134]

I thought I'd chip in on this one.

I have a free flooding 1:24 styrene barge built for my Jasmin (Model Boats free plan), it gives a decent displacement but is light to transport. With hindsight I should have used bigger vents and drains but it still works well.

Also have built a Griffon from the free plans on the web, one suggestion I would make would be to build it at a smaller scale as it came out too big to easily transport in the back of the car, still an interesting build though.

[Paul TParticipant @pault84577]

Hello Ian

Its nice to be back and I am very grateful to the NHS for enabling my return especially the ambulance crew who worked on me for half an hour before whisking me off to ICU.

I am playing around with my own hovercraft design so its not the Griffon I have learnt a great deal from Marks designs but decided to create my own which is more suited to foamboard.

Its slightly smaller than the Griffon so it will fit into an average family car, big thanks to Trevor for the suggestion.

Paul

[Ian GardnerParticipant @iangardner62867]

I know the NHS can get a lot of flak these days but I think we have much to be grateful for.

The suggestion to build Griffon smaller seems a good one, although my instinct is to always go larger! There is quite a useful DVD on model hovercraft with some stuff from Mark Porter although I was a bit dissapointed at the lack of hard information included. There are some good shots of Griffons in action. If you want a borrow, pm me.

I will still watch your progress with interest.

All the best…Ian

[Paul TParticipant @pault84577]

Hello Ian

Thank you for the very kind offer but I have enough info on model hovercraft especially the Griffon. I might be able to return the favour though…what hard info do you need?

Paul

[Ian GardnerParticipant @iangardner62867]

Hi Paul,

I shan't actually be building the Griffon now as the panic over the water has passed- it was a sort of emergency contingency.

Have fun with it though- that's what it's all about!

Ian

[Paul TParticipant @pault84577]

Getting bored with sitting still so I have started playing around with the foamboard hovercraft idea.

Straight forward foamboard build with 6x6mm timber strengtheners.

Lift motor support beams

Thrust motor mount

Paul

 

Edited By Paul T on 14/04/2013 19:24:51

[Ian GardnerParticipant @iangardner62867]

That's looking very interesting Paul. What size did you go for in the end? Good luck with making the skirt- I believe its possible to purchase a ready made skirt at the original size. I must say, it's what put me off a bit.

I have recently been researching the use of foam block for models, as wood is such a ghastly price these days. A friend offered me a lump of blue foam to play with yesterday and I noticed a gent in the latest Model Boats had used foam in his sail training ship. I gather it can be sheathed successfully with cloth and Eze Kote, so am seriously thinking of giving it a go when I (finally) start my enlarged Guardsman- got a bit sidetracked with another project. I'm easily diverted!

Hope you are still on the mend- you must be feeling a bit perkier to have made such good progress with the Griffon.

All the best….Ian

[Paul TParticipant @pault84577]

Hi Ian

Its 850 x 520mm and the skirt will be made from Ripstop Nylon material stitched together by Jane.

Having fun trying to balance the motor output with the right size blades.

Thanks for asking I am feeling a little better but still very weak. Just got fed up with sitting around.

 

Paul

Edited By Paul T on 15/04/2013 19:06:26

[ashley needhamParticipant @ashleyneedham69188]

Paul. Nice to see you back.

Has this post officially moved on to the hovercraft now??

Very interesting and exactly the sort of material for this sort of thing. Brushed?? Several rudders behind the airscrew? Sossidge skirt or finger?

A small ducted fan unit would sit nicely in the lift hole, no faffing about with prop sizes.

A ducted fan, moved by a servo would of course be ideal for the pusher as well..also no messing with matching motors/props.

Ashley

[Bob Abell 2Participant @bobabell2]

Hello Paul

You take it easy, you've been rather too active of late!

Now then…

I know hovercraft have skirts, but for water use, why not have a simple wooden edge?

Or is this an obvious daft question?

Bob rocking the boat again!

[Paul TParticipant @pault84577]

Hello Ashley

The thread hasn't changed as I am are still exploring the pros & cons of using foamboard, ducted fans would be ideal if it wasn't for the price but the fan blades from computer cooling equipment do appear to have great potential when coupled with 500 size motors. I am now hunting fleabay for a couple of 150mm cooling fans to test the theory.

Hello Captain Bob

I am under strict supervision when working and I'm not allowed into the workshop so everything is being done on the dining table, actually its great way to work, being comfortable sat in front of the big TV and being waited on with a constant flow of hot drinks.

Re your suggestion about running without skirts, Christopher Cockerell had the same idea and he described it as a momentum curtain but it didn't work very well as SRN 1 struggled in heavy seas.

Paul

[ashley needhamParticipant @ashleyneedham69188]

BUT a small lip and possibly some suitable ducting to take the lift air out to the edges (and point in) would probably be fine for carpets, floors and calmish ponds.

An SRN1 is on my list somewhere, but there is really nowhere to put the gear unless you made the craft very large or deep, and it would have to be skirtless of course.

Ashley

[Paul TParticipant @pault84577]

Ashley

I imagine that a model SRN1 would have to be at least 2ft in diameter just to be large enough to carry the RC equipment….but if ever a design suited a ducted fan.

 

The original designs for SRN1 contain a great deal of interesting calculations dealing with airflow but as can be seen from this photo the craft had a very limited ground clearance.

 

 

Eventually though a skirt was fitted which enabled higher speeds over rough water and greater dry ground clearance

 

Paul

(Images removed du to copyright infringement request – Colin)

Edited By Colin Bishop on 05/03/2021 15:05:42

[ashley needhamParticipant @ashleyneedham69188]

Paul. It was modified with a box on the back for a gas turbine later on as per picture, so scope there for gear. A more "solid" cabin could house gear, and even the front ducts coiuld be used, as the craft doesnt need reverse, it just needs to spin around!

I modern LiPo would easily fit in a slightly fatter hull as they are very thin. Hmm….

I like the idea of NO skirt, its like my airfix model was, and if a solid/slotted bottom weas used, with enough forward propulsion the thing would become a semi-skimmer anyway and lift on its own, like a flying saucer.

Ashley

[ashley needhamParticipant @ashleyneedham69188]

paul, a moder Lipo would fit underneath the hulla s they are very thin. gear could go in a more solid cabin, and even the front ducts could be used, as the craft will spin easily and so not need reverse.

A solid/slotted bottom would be fine on a lake, and this would become almost a skimnmer if there was sufficient forward propulsion.

What a great project for foamboard…ideal I would say !!

Thinking about it, only a modest lift would then be needed and some small ducted fan units would sit comfortably in the ducting bend, to provide the thrust rather than bleeding off lift air. Small gear should easily be accomodated in a slightly fatter hull surely..? Seperate thrust units will do away with servos and linkages.. cor…on me list!

Ashley

[Paul TParticipant @pault84577]

Ashley

Looks like you are talking yourself into building one…….be careful these hovercraft things are addictive.

Paul

[Bob Abell 2Participant @bobabell2]

Just for interest only…….

In the 50`s or was it the 60`s?……There was a daily Hovercraft service from Blackpool to Rhyl!

We never had a trip on it, as it must have been quite expensive?

What a treat we`ve missed?

Bob

[Paul TParticipant @pault84577]

Added a few more bits before running out of steam.

[ashley needhamParticipant @ashleyneedham69188]

My one and only ride on an SRN6 over to the IOW, as a small boy.. I remember the trip as damp (the whole craft appeared to be..damp).. noisy and none to smooth.

One presumes the diesel engined ones are more better at everything.

Paul. Looking good and how rapid a build! Might it be possible to slim down the rear tunnel support any..?. I realise that you need the strength of material of course. but.. And I am not criticising, just offering my opinion as usual.

Control is the issue on hovercraft and large multiple slats at the back appear to work best as far as I have seen in my limited experience (as no hovercraft perons likely to post!!!)

Ashley

[Paul TParticipant @pault84577]

Hi Ashley

The front panel of the thrust unit is a critical buttress support and unfortunately the calculations show that it needs to be this size and shape to resist the push of the thrust unit.

You can see from this photo taken during construction that the walls of the duct itself are quite thin

Paul

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