By now we were really beginning to coalesce into a very slick team and we arrived at the side of Loch Fad to find a pleasant 14 degrees and a light south westerly breeze - perfect running conditions.
We went through the usual inspections and checks then had lunch so it was around 2.00pm when we got down to the serious business of the day and it was something of an experiment. First thing first, we opened the back of the boat shed and got K7 down to the water.
K7 is fitted with two LP boost pumps, one down in the hull in a collector tank and another, a hastily added bodge from the dying days of 1966. We'd had extraordinary difficulties in setting up the linkages to the Orph' such that it would start cleanly then run up to idle. It was easy on the test rig but nigh-on impossible in the hull. We did bottom the issue eventually long after our return from Bute but that was back at HQ and on Bute we simply had no answer to it. The engine would start cleanly but the idle was too high and if we adjusted the idle we got poor starting. But we did notice that with one boost pump disconnected the starting and idle seemed happier - or so we thought.
Thursday was the day we would reconnect it and see if it made a difference. As I'd run up the engine many times I climbed aboard knowing exactly what I was looking and listening for while the team fussed around preparing for a static run.
Because we didn't have the on board start system ready for Bute we had to start from a separate boat and plug the air supply in through a fitting in the hull. It worked brilliantly on water but to do static tests we had to haul the start boat up the beach and it was bloody heavy!
We did one static run to put some heat into the engine, and apart from its obstinate insistence on idling at 50% rather than 37%, it ran well. 50% might sound like lots but you have to remember that the engine makes 80% of it's thrust in the last 20% rpm so at 50% it's not blowing especially hard - but it was annoying that we couldn't get it down because K7 would waft along happily all day at 100mph on 50% throttle such is her efficiency one up and out of the water. It was something for the pilots to manage from the cockpit for now and we'd fix it later.
With a good heat soak the engine was shut down and the second boost pump connected then we fired up for the second time.
Again, I listened and observed carefully for any changes but light-up was normal, temperatures stayed in limits and idle settled at 45% so nothing gained - nothing lost. We shut down, drained the catch tanks (very much not allowed to let any offensive fluids off board into Fad so everything was pumped to a catch tank that we emptied ahead of launching) and prepared to launch.
Malcom carried out his usual safety briefing on the slipway, this threw up no issues and we were off. The brief was for Stew to run to the end of the loch then turn and come back without shutting down - a task that had proven difficult so far due to the awkward and contrary control linkages uncommandedly shutting down the engine when coming out of the throttle. Ted had given Stew a good briefing on how to deal with this annoying problem so we hoped all would go to plan
This was it - time to strap Stew into the hot seat and see how he got on. We never had a doubt.
The wind had come up a little as the day went on and it was blowing straight up the jetpipe so we were concerned about hot starting so we tucked K7 in tight against the dam at the end of the loch and got everyone into position.
The engine lit cleanly and almost immediately K7 was moving with the tail wind, she weather-cocked around the place and Stew later commented on the lack of a rudder on that great big fin on the back - that wasn't our idea. He soon had K7 on track 'like taxiing a Hawk' then hit the throttle. K7 leapt up and howled down the loch. Stew noted that the steering seemed less effective at high speeds than lower down, the opposite of what he expected, but she certainly accelerated hard according to his description. So hard, in fact, that he came out of the throttle too soon and left a lot of spare loch at the western end.
Stew passing Keanes Cottage on the shores of Loch Fad, steady as a rock. Keanes Cottage is a holiday home owned by the Mountstuart Trust and we had to speak with the people who had rented it for the weeks we were there in case they had any particular aversion to gas turbines outside their window in what would otherwise be a very tranquil setting. Needless to say they couldn't believe their good fortune at having us along and brought their deckchairs down to the waters edge whenever we were running.
Regardless of the surplus and unused stretch of loch, Stew taxied round without the engine flaming out, lined up on track, fed in a bit of throttle until she lifted then floored it for the return run, which proved arrow straight and peaked at 136.7mph.
'Goes well in a straight line' he noted.
But he wasn't so keen on the amount of spray that blasted the canopy whilst accelerating.
Half an hour later we'd uplifted more fuel, done our checks and Stew was strapped in for his second run of the day. Again, this would be up the loch, taxi round and back again and this time it was even better. As K7 began to lift he opened the taps to 70% and she was off. Off so quickly that he backed off slightly and cruised up the loch at 55% and 140mph. Another taxi round at the end of the loch without the linkages claiming another victim and the return run was just the right length this time with the boat coming to rest closer to the dam. We were caught a little by surprise, mind you, as the wind had by now reversed direction and was blowing the boat towards the rocky dam. No problem, a couple of drysuited personnel were quickly on the scene but it went into the log book for future reference. We were there for crew training, after all, so it was all good experience.
That was Stew done for the day and it was a big success - he handled K7 perfectly having worked with Ted all week but now we had some new trail blazing for Ted to try. Anything new was given to Ted first, he being massively experienced in hydroplanes, and this time the plan was for him to go up the loch in the usual way then turn around and perform a slow run on the way back down. As the agreement was that BBP would be operating K7 in future we wanted to explore the lower end of K7's performance envelope too in case we were to demonstrate on smaller bodies of water or just generally at lower speeds. The ultimate aim was to se if we could put on an exciting demonstration on half the loch using half the speed so once Ted turned round at the top he would attempt to return at whatever low speed K7 would allow whilst remaining up on her planing points.
After Malcolm's obligatory safety meeting we fired K7's engine at 17:28 and Ted was off. Seven seconds to climb onto the plane then full throttle through the narrow part of the loch before lifting at 125mph and cruising back down to taxiing speed. And then the old engine shutting down gremlin got him. It hadn't molested Stew all day but as Ted throttled back the engine flamed out. The first warning was of low oil pressure and Ted was swift to open the HP cock but there wasn't sufficient energy left in the rotatives for the engine to accelerate without over-temping so as the jetpipe temperature soared past 550 Celsius with no indication of levelling out, Ted shut the engine down. This meant a long chug up the loch in the start boat or a long tow home. In this instance we decided to take the start boat so Ted could still have a go at his low speed pass so he was told on the radio to hang on til we got there.
But as things turned out it wasn't to be. We'd used a lot of starting air and as we were running a compressor at Bute Blacksmith's workshops and they were finished for the day we were on about the minimum amount of air for a clean start - or so we hoped. Ted hit the go button but the engine was slow to light and never got into its stride with Ted choosing to abandon the start as the JPT approached limits. And that was the end of our running for the day. Ted also mentioned that at one point the steering hadn't felt as expected so that went straight to the top of the list of jobs for the following day. It's impossible to overstate how thorough we were with every last nut and bolt and steering was certainly going to get a good going over if Ted had any questions over it.
The log for the rest of the evening makes interesting reading. A drop of hyd oil was found on top of the water brake ram causing a big inspection there too - it was a false alarm. The main planing wedge was drained but found to only contain a spoonful of water while the starboard float wedge contained half a pint of Loch and its opposite number was dry inside. The rudder was sharpened in case the flow was separating from it (a known problem on K7) and the batteries went on charge, to name but a few tasks carried out before we buttoned up the boatshed for the night. A much more thorough maintenance visit would ensue in the morning.
Friday would be the last day before we got a rest and we were all looking forward to it - we'd been flat-out for months and we deserved a break.
And finally - turn your sound up loud and enjoy Stew's first start and release. Video courtesy of Frankie Jordan, Isle of Bute.
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