Summer 2005 - Part 2
Now you just know something is going to go wrong.
Whittelsey was a bank holiday event which meant three days of racing and six possible Novice races.
The practise session Saturday morning was a laugh. I was the first one out so headed off around the course. Now I really had listened to the race director's briefing given by Gayle Spedding and I'm sure she described the course very well, but it sounded very confusing at the time. It's only once you get out there that it makes sense. So I headed out across the lake looking for the marker buoys, but I couldn't see them. The marshalls were pointing way back to my left so I did a quick 180, saw them in the distance, and eventually got back on the race line! The water transitions were no problem and generally things went well except for one part of the course where I was skimming along and suddenly the nose dipped a little and I felt a sudden deceleration. Aha - the famous plough in effect that I had heard of but not experienced so far ! I hung on as best I could, didn't let go of the throttle, and ended up doing a 360 pirhouette. In that one particular straight stretch of the lake it was the same for every lap of the race and every race - I could feel the craft wanting to nose down every time, so I learned to lean back and keep the nose up.
On the 2nd race of the Sunday (4th race of the weekend) I was approaching the finish line and I could see the chequered flag ahead, I had just left the water when suddenly BANG and the engine revs went very high. I knew what had happened and pulled the lanyard to cut the engine. The belt had come off the back of the pulley again, having first eaten a U-shaped channel into the bottom of the duct, and worn itslf down to 1 inch wide (from being 2 inch wide). Having recently re-shimmed the lower pulley to hopefully prevent this, I had been checking it before every race and it had seemed fine so what had gone wrong? I didn't know, but I had now stopped 20 metres from the finish line. Not that it really mattered though. I had completed enough laps to count as a finish, but stopping so close to the chequered flag kind-of hurt a bit, know what I mean?
Ken from K&M was at Whittlesey and was able to sell me a new 660H200 belt. At £37 pounds each I didn't want to wreck another one so we retired home to make a flange to go onto the rear of the pulley. Why it was supplied with only a front flange I don't know, but it needed one at each end. This one was made by punching out a disc of steel, and then punching out another disc from its centre. I welded it on to the pulley with 4 short runs.
I was still very unhappy about the craft's lack of power - the acceleration at the start was very poor, so I decided to go from 8 blades to 6 which meant splitting the fan hub, removing some blades and re-adjusting the remaining 6 blades to a steeper pitch - as each blade would now be absorbing more power.
Pictures from Whittlesey:
Steve Walsh (#213) brought along an inflatable hovercraft that folds in half and can be transported in the back of a transit van. Amazing!
Tony Broad brought along his new super-lightweight craft which performed well.
“Pest” (Peter Symes-Thompson #161) with his new home-built craft .
Sunset over Whittlesey lake, after the chip van had arrived.
Return to Black Ditch
The club requires new drivers to complete 15 Novice races before you race in the full Formula. Things were going well as I had completed 13 Novice races and so needed just 2 more. There would be 4 Novice races available over the Black Ditch weekend...
Left picture from Paulz Video at http://www.hovercraftvideo.co.uk
and used with kind permission
Saturday's practise was interesting. I came out of the water for the first time and the revs immediately dropped to around 4,000 rpm. I looked at the engine and saw that the HT lead to the front spark plug had parted company from the connecting cap. Thinking I could push it back in, I picked up the end of the lead. BAD IDEA. I don't know exactly how many volts went through my hand* but boy did it tingle! The marshalls offered to pull me to the side but I reckoned I could fix it on the spot, so I stopped the engine, made the connection with the electrics OFF and then restarted and drove back to the paddock.
Above: Two F2 craft, Brian Reynolds #40 and Bob Coles #54 at Black Ditch 2005
By the end of Saturday I had completed 2 more races without incident (apart from destroying a few catch netting fence posts) which meant I had completed my Novice races. However I did not think the engine was up to F3 level and rather than be a hazard to other drivers I thought I might as well stay in Novices for the last race day of the season.
Sunday's first race went equally well, so that was 3/3 so far. Then, on the Sunday afternoon, in the last Novice race of the year, I was approaching the water and the revs started to drop a little. I hit the water (for the 20th time that weekend) but this time the craft ploughed in and I got chucked out. I went in really quickly and the only thing that I can remember was thinking "I'm going in!". I felt my craft going over the top of me, powered by its momentum, and then I felt another one going over. I resurfaced facing the water-entry, to check that I wasn't going to be hit by another craft. I saw the marshal waving a red flag to stop the race and I thought "why are they stopping it rather than just waving a yellow caution flag?". Then I turned round to see Rachael Gifford's craft stuck on top of mine, and Rachael nowehere to be seen. I was concerned as I thought she was still under the water, but it turned out that she had been thrown out and was on the other side of the crafts. The water was very weedy and the bottom was very muddy so I swam to the crafts and got in to the rescue boat.
Pictures from Paulz Video at http://www.hovercraftvideo.co.uk and used with kind permission
The marshalls took us both to the side of the lake and we watched while they recovered our craft. Unfortunately they had to sink my craft to get Rachael's off, although several people were very impressed by its buoyancy. Then they towed them to the bank and trailered them back to the paddock. My craft had a cracked thrust duct, a very twisted duct guard, and a bent radiator - and the engine had taken in water. Rachael's craft had a ripped bag skirt, which was repairable.
So that was the end of my racing for the year. I'm just glad that I DID get chucked out, otherwise I might have been truly squashed between the two craft! And if you are going to go out with a bang - do it in front of an appreciative crowd!
Strangely the bits of the craft that I built - hull, fan frame, bracing struts etc were undamaged, but the bits I bought - the duct, guard and radiator were very damaged. In fact looking back over the last 16 completed races, and several that were half finished, the craft suffered a fair amount of knocks and the hull never needed repairing. But then again, if it hadn't been so tough and heavy maybe it would have gone faster!!!
The duct was not competely destroyed. Someone with glass-fibre mending experience could probably fix it quite easily, but not me - I'm an aluminium worker.
So if you are interested in buying this 900mm duct it is yours for £1 ono - buyer collects.
I am going to replace the duct with a similar 900mm one (in yellow). The engine was very worn anyway - a 65psi compression test reading from the cylinders isn't great, so I'll fit my spare engine and see how that works. The radiator was from a bike scrap yard, but I have got two original TZR rads so maybe I'll put one of them back.
But I don't think I will be racing again. That was too close!
Nobody in my family wants me to race and I don't want a broken leg, a dislocated or broken shoulder or a punctured lung. I had always wanted to build a hovercraft and now I have. The construction was a great experience, the club spirit is great, but for me the racing was only fun - and at the same time extremely stressful. At the end of the day I'm an engineer, not a racer.
I'll go to hover-ins and do some marshalling at races, and I might even build a big twin-engined cruiser one day, but I don't think I'll be doing any more racing.
* Yes I know it's electrical current that passes through you when you get a shock, but it doesn't sound quite right when telling the story.