RESOURCES
About HovercraftAfter a another couple of weeks work, it was time to put the skirt on. This took a couple of hours with some help from a friend. “Let's fill it up with fuel, and start the engine” he said. So that's what we did. And it started. First time. The first hover was literally just up and down on the roadway (not a public road, I should mention) outside the house. The usual sort of problems showed up : a connection to the oil injection tank leaked, and the engine exhaust gas and cylinder temperature gauge didn't work. The oil leak needed a new hose clip, and the gauge was cross wired by the fool who wired the instrument panel (me).
A short time later, and it was out to sea for the first time, a slightly worrying experience for a novice pilot, but interesting, nevertheless. The craft performs exactly as advertised. Nothing fell off, came loose or gave any cause for concern, unlike the pilot, who still needs a lot more experience…
The slipway by the house is narrow and steep, and whilst going down it was easy, getting back up involved full power with someone pushing the craft as well, as due to the width of creek, its more or less impossible to get up any speed when approaching the slip. The width (about 3 metres or 10 feet, between high quay walls) also made approaching at speed rather a dumb thing to do.
However, about 500 metres further down the creek is a marina with a nice, wide and gently sloping slipway, and I'm pleased to say that negotiations to use this one instead have been successfully concluded.
Just waiting for the gales to blow themselves out, and then its back to the water.
“Dearest, I think a hovercraft would be really great on all these mudflats, much better than a boat. The tide's always out you see, and you'd never get a chance to use a boat, whilst a hovercraft…”
“Well, possibly, but only if you call it MID LIFE CRISIS”
That's more or less how the project got started. March 2003 saw me visiting Neoteric in Terra Haute, using up lots of accumulated frequent flyer miles to get the trip across from the UK for free. One day with Chris Fitzgerald and his team had me hooked – after a couple of hours on the Wabash river, I placed an order for a Hovertrek deluxe with the Hirth fuel injected engine. I've been a fan of fuel injection ever since I had a Lotus sports car with twin Dellorto carbs which were permanently out of tune. (it was probably nothing to do with the carbs, but thats another story)
Chris got a rush of orders around that time, and the craft wasn't ready until late August, by which time I was off driving the Silk Roads across China for two months, so eventually it was shipped mid October, arriving at the end of the month exactly on my birthday, how did you know, Chris ?
I bought the craft with its trailer, but without the US standard tow hitch and electrical system, as both would be illegal in the UK. Neoteric simply put all the parts in the hull, and strapped everything down with the cover. The craft and contents were then winched onto the trailer, and the whole lot simply pushed into a standard 20' shipping container. The container was unloaded and transferred to the shipping company's depot in less than 48 hours, so my first problem was how to get a non – towable trailer from a depot about 90 miles away to the assembly “workshop” (OK, two car garage). This was easily solved by hiring a flatbed car recovery truck and driver, who for about $150 collected the trailer and craft and delivered it a couple of hours later.
John – he lives next door, has a boat called “The Oldie” and makes several appearances in this epic – rushed out, and helped me unload the boxes. At this point, you have heaps and heaps of stuff. Much doesn't make a great deal of sense. I tried checking to see if everything was there, but gave up, because there isn't a parts list, but I found all the big bits. Well, not all, I couldn't find the windscreen or the skirt retention strips. These are (a) pretty large, and (b) rather fundamental. In fact they were there, but because they are quite long they had been slipped into the port lift duct. Only took a day to find them… Nothing then happened for a couple of months, due to illness in the family, but around Christmas a start was finally made. The first hole you drill is the worst. The second isn't much better, but by the time you've done a hundred or so, you get blasé about drilling this shiny new fibreglass tub thing you've just bought. Like Dave Reyburn, the first contributor to the Hovergarage, (thanks for all your advice Dave, your contribution has been really useful) my first job was to install the skirt retention strip. I treated myself to a small compressor and an air riveter, which made this job really easy and kept my hands soft. If you work on a computer all week as I do, your hands don't take to hand popping 3/16 inch rivets without blisters. By the way, don't look at the video on this one, its now completely different. I did, and started incorrectly, but it all came out right in the end. Actually, so much has changed that I personally found the video not very helpful, and it can now be rather misleading. My way of working was to look at the parts, look at the instruction book, which is brief in the extreme, and only if I couldn't work out what was required, look at the video. At this point the video invariably seemed to be using parts I hadn't got, so it was an email to Chris instead.
The first small problem happened at this time: the fact that the craft was mostly Imperial in its fittings. The 3/16 inch rivets used in the skirt retention strip are actually a snug fit on a 4.8mm drill, which my extended metric set happened to have, but I was lucky with this. In the end I bought a set of imperial drills from a specialist supplier. Only when I got to the end of the job, at the bottom of a box full of electrical bits and pieces, did I find that Neoteric had actually thrown in a 1/4” and a 3/16” drill.
Next job was taking out the engine, and mounting and bonding the lift duct air splitter. I used an engine hoist, and guess what – the trailer wheel gets in the way of the hoist leg, just like Dave Reyburn said. The engine came out OK, and the lift duct splitter fitted without problem, but getting the engine back in took the combined efforts of John and myself for what seemed like hours, with much old fashioned British cursing of all things foreign. The engine mount spacing washers in particular were difficult, invariably slipping out just as you thought you'd lined everything up. At this point you have to ignore the video again, as the engine fixing has been greatly simplified, using the thrust bell housing, although John & I did manage to push one of the well nuts right through its mounting hole. Fished it out again with a pair of fine long nose pliers, and it all went in properly the second of third time.
I then decided to drill all the big holes, mostly because this makes a lot of dust, which its nice to get out of the way early on. The large holes for the instruments and tacho were made using hole saws, which over here all seem to be metric equivalents of imperial sizes so there was no problem in finding the right saw for the job. The smaller holes for the switches were drilled using a conical “sheet metal” drill. These are stepless, cone shaped bits which can drill almost any size hole in thin materials. The advantage is that the hole is very clean, with no cracking of the gel coat around the hole. Disadvantage is that the hole is as big as you make it, so you have to go slowly, fitting the part all the time. I'd recommend this way though, its much less stressful on the material than an ordinary large diameter drill bit.
Neoteric have marked out many of the drilling locations, but they can be difficult to see. I found a soft pencil rubbed over the marks helpful. Instruments and handles were uneventful, although I was a bit surprised to see the tacho reading 1500 rpm, without being connected to anything. I am assured this is normal. Reverse thrust buckets also went in fairly easily, although there was a bit of straining to get the starboard bucket clear of the exhaust “bump”. The actuators seemed very stiff when they were first installed, but this could have been a lack of lubrication, and also that the garage was only just above freezing when I was working on them. They are much easier now. The cables from the actuators don't now go to terminal blocks in the lift duct, but are directly soldered to the cable from the bucket controllers. Each soldered joint was insulated with heatshrink, and then then the entire cable covered with a glue filled heatshrink tube, which forms a watertight seal after shrinking.
John & I fitted the exhaust. On the Hirth engine, this is different to the funny bent sausage thing the Fujitsu engine uses, and looks much more like a proper silencer. Fitting the bell joint to the exhaust and its retaining springs is a dangerous occupation, which almost certainly contravenes all European health and safety regulations. Those springs are lethal. Again, use of large pliers, screwdrivers and lots of sticking plaster (on John and myself) and eventually the job was done.
The actual silencer bit fitted easily. Both the manual and video are incorrect here – the Hirth silencer doesn't use the predrilled plate or the heat shield, the tail pipe simply sticks out of the hole in the hull, using the steel wool and mounting flange.
The seats went in next. Rear seat was easy, the front not too bad, but here is my only real engineering gripe with Neoteric – the location of the holes you have to drill and tap for the front seat wheels. I drilled and tapped at the marked locations (had to buy an imperial tap set as well), only to find that the seat was “too high” and the rearmost of the two sliders couldn't be closed, and that the roller didn't make contact with the slider bar.
After much measuring, I found that whatever I did, it just wasn't going to work. I couldn't raise the wheel positions enough to get the rearmost slider to work properly, as the seat frame is only about 1/4” off the floor of the craft as it is. My solution was to leave the seat wheels where they were, and to modify the slider, using spacers made out of 1/2” thick aluminium bar and longer stainless steel bolts. It all works well enough now, and is very stable.
The rest of the mechanical components fitted in well enough, including the glove boxes, which caused much merriment by having two cup holders in each – it being part of European folk lore that in the USA products are solely judged by the number of cupholders they have.
Next thing was the electrics. Now I have (a) the deluxe Hovertrek with reverse thrust buckets, (b) a salt water package and (c) a fuel injected Hirth engine, complete with an engine management computer. This means that all references to the terminal blocks on the engine are spurious, and you need to work out which wire goes where. I needed Neoteric's help with this, as there are two yellow wires coming out of the Hirth engine, and even the Hirth manual doesn't mention them. Chris, can you do a sketch drawing for the next person ?
I'm afraid I didn't like the harness construction used by Neoteric, so I redid most of this using Raychem “Duraseal” connectors, which are crimp connectors with glue filled heatshrink sleeving. Once crimped and shrunk, you get a permanent watertight connection. If you do this, its wise to invest in a proper ratchet crimp tool.
I think this brings me up to date. I have spent only around 4 hours per week – not really more – since Christmas, and its now the end of March. I think it needs about another 8 hours work until the maiden flight. I have yet to order the Mid Life Crisis decal, but I am still being told I can't launch without it.
I'll keep you posted about the rest.
-Nigel
