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 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.
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.
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.
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.
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.
Making a new top mould.
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.
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.
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.
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.
I 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.
One 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.