A temporary halt

Things have been going very slowly on this build as you can tell.

The plan was to build a gnarly F3 shaft drive and see what I could do in that. However, it has taken too long to get this far and my Son is now 11 and old enough to race. The problem is that I don’t want to put him in a big heavy F3 that he will struggle to control.

So, I’ve decided to put this build on hold a make something he and I can both drive.

Here’s to Spin Dizzy.

Flow straighteners

After fitting the duct to the hull it is time to fit some flow straightener vanes. There are some basic rules here.

  • You need a different number of flow straightener to the number of blades you have. This avoids a nasty beat frequency as all of the blades pass in front of all of the straighters at the same time.
  • They need to have some shape to guide the air from its swirling path off the blade to a flow parallel to the sides of the duct.

I borrowed some moulds to make a set and all was going well unitl I tried filling them with foam for strength and the deformed beyonr recognition 🙁 My old freind Dan came to the rescue wth various vanes he had lurking in his collection. Not only that but he came rounod to help me fit then and also had a pair of rudders. Top man.

The duct

VLUU L200  / Samsung L200The duct is 1M in diameter, quite large for an F3 but I figured it would be about right for this craft. The duct was made by my old friend Dan  who was doing it as a plug for a duct he was building and it was no longer required.

I collected it on a filthy night, strapped to the roof of the car as you can see. You can make out the Kevlar containment area that should hold everything together if a blade lets go and tries to leave through the side.

There is also a flat “plate” running all round the duct. This is to help to keep it circular, particularly where the blades run. It’s quite hard to stop a duct from flexing and as long as the part with the blades in stays circular, the rest can move around a little.

The planing surface

074456a094d63b73f15a88acce6a5b13The Outlaw mould was made ready to take part

Next the various layers of Chopped Strand Matting (CSM), Diolen and Kevlar are cut/torn and laid out on a ground sheet until needed.

36f33050fbe0ffb8392f327294b95707The finished part was popped out of the mould after a few days…

But took an amount of mould with it.

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Random orbit 3 – Outline and hull

Introduction.

By now I had a new mould for a top deck/hull and a polished mould for a planing surface that I thought would give me one piece from which I could take another mould.

But, we’re getting a little ahead of ourselves here. I mentioned in the introduction to the Outlaws that I had formed a plan. the plan was to build a new craft on a light, interesting hull. It also involved twin ducts because I like twin ducts and a four stroke engine because I like four stroke engines. I’d still go shaft drive because otherwise engine choice is a bit limited.

 

The hull.

We’ve seen how the top deck plug was mounted, buffed and a mould taken. The next step was to take a part from that mould.

For reasons unknown I don’t have any pictures of the new mould. Suffice it to say that the plug was pulled of the frame and the mould put onto it. Now I have a mould on a nice frame that can be rocked over at a jaunty angle to make laying up easier.

The layup.

First up, after waxing and polishing comes a couple of layers of gelcoat. I chose a letterbox red. Then a mix of CSM and Diolen. I think I put down one layer of CSM followed by Diolen followed be CSM. It’s been a while, cut me some slack.

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The front duct.

The plan was to use two fans, one for thrust, another for lift. The list fan duct is made from GRP as to be expected and was given to me by a freind who has moulds for this kind of thing and a spare duct.

df645fbb4f2efb1831e98d187fc2fd45It was quite a simple matter of finding the centre of the front section of the hull, cutting a big hole and using glue and rivets to hold it in place.

Refurbishing the moulds

Making a new top mould.

85ffe21bfadbd70eecb52846a680a80aFirst, I built a frame to hold the plug. Waxed it well and put on two coats of gelcoat in a colour I was unlikely to use for a hull (this makes things easier later)

9919be69f430d92dcdb01d17403cbe98Next the matting goes on. If I remember correctly 6 layers of CSM but the job is so boring I may have mis-remembered.

 

The mould for the planing surface.

The mould for the planing surface was made from a plywood frame with a hardboard surface and was in a very sorry state. After several attempts at restoring it I decided to make it good enough to get one part out of it and make a new mould from that.

074456a094d63b73f15a88acce6a5b13The mould above has been filled with pounds of car body filler, painted and waxed.

 

 

The Outlaws

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I decided that I had gone about as far as I could go with the Motocyclone and although I was somewhat sad to see it go, I had to move it on to someone else and build new one. I tried starting the new craft while I still had V2 but it really wasn’t a good idea. What I had done however was form a plan.

The plan.

First of all I wanted a new, light hull. Weight is very important in hovercrafting and V2 had become too heavy. I was unsure which hull too choose but “cheap” was important and “interesting” was important too.

 

The search was on.

A few years ago I spotted a craft I hadn’t see before. It was a twin fan design in turquoise and was called “The Texan Outlaw”

I rather liked the look of that and after some chatting I found the Geoff Sweetman was instrumental in its design and build. At the time I wasn’t on the lookout for a new craft but now I was. It turned out that Geoff had the moulds and was looking to sell so I set off down to Kent in August 2008 with a borrowed trailer, some cash and a slice of optimism.

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What you can see in the picture above is my old friend Jake getting the bits off the trailer. What I actually got was a two-sided wooden mould and a GRP plug that had originally been taken from the mould and had then been modified to have a centre console. You can see the hull side of the mould is hanging down but that won’t be used again so it doesn’t matter. The top side is the planing surface mould and the plug is resting in it.

 

The first step was to be the refurbishment of the moulds and the start of the Outlaw dynasty.

 

The end

b68814ddfa8520c9ffb976e0af494753I had a lot of fun with Random Orbit mk2 but I decided I wanted to move on and that I couldn’t get it to go much faster so I sold it on.
The last time I saw it the old thing was still going strong. The majority of the hull is about twenty years old by now and it’s not getting any lighter but it still gives me a wee twinge of pride when I see it. In 2008 it was driven be David Northall in the HCGB national championship. It was sold on to race again but I’ve lost touch with it now.

Keep your eyes on ebay.

Engine and fan frames

d6b6df4d18a828b64846c3aa3e62913cOne of my overriding design ideas for Version 2 was that the duct should be clear of obstructions and that the engine was to be as low as possible and out of the way. To achieve this I decided to put it down in the corner of the craft. In order to get it to fit and too make use of standard length drive belts that didn’t give me much height and so the engine frame couldn’t be the usual chunky steel affair.

a8b0c0b3ff33d3cd133b75bb52a1e901Because of this and also because I fancied having a go at it I made the engine frame out of carbon fibre. As you will see, I didn’t think to take a photo (despite it being a thing of beauty), but I did take one of the mould I made it in.9434348ec2baec326d616fb42f536b1e

The hull

The Hull

Firstly an apology. For some reason I didn’t take nearly enough photos of this… Sorry.

In most cases, when you fit a lift duct to a craft that didn’t have one, you cut a large hole in the front deck and fix in a glassfibre duct.

The Moto cyclone doesn’t really have a front deck to speak of so that’s not an option. You can see from the pictures of Random V1 that there was a black fly screen at the front. This was fixed to raised lip that runs all around the cockpit. The new duct is a large moulding that fits over this lip and about a third of the length of the craft.

The inside wall of the cockpit was removed as was the buoyancy up to about half way down the plenum. The new duct was fitted and because I needed the buoyancy and didn’t need a very wide cockpit, a large chuck of the foam was glassed in on each side of the cockpit.

At the back a 900mm duct was fitted in place of the 750mm. This tme there was no need for a splitter plate. The flow straigteners are standard this time and were bought from K&M products as was the duct.

A centre console was needed. The old one wasn’t long enough as there was going to be a prop shaft running the length of the craft and it’s not a good idea to crouch down over an un-guarded prop shaft that’ rotating at 3,500 RPM. A new console was built. This was made from GRP layed up on to a foam plug which was then removed. It wasn’t pretty but it was functional. Other guards were built from steel and aluminium to cover other exposeded bits. More on that later.

A short step from where you are.