Repost from: Longbow Jet Hydroplane UK
– Update by Dave Aldred | Sep 27, 2019
Back with the construction of our jet hydroplane Longbow, we are very grateful to gas turbine expert, Ian Bennett for his guidance with regards to the correct part numbers for some of the connectors to the gauges and electrical fuel pumps serving the twin Viper jet engines for the craft. These connectors were not listed in the engine manuals that we had, so Ian really did come to our rescue on their identification and he has a fantastic website for the gas turbine enthusiast, that we cannot recommend highly enough if you would like to visit: http://www.gasturbineworld.co.uk/
Armed with the correct part numbers we were then able to go to our sponsor, RS Components and within the many thousands of parts that they stock, they found they had exactly the right connectors for the rpm gauges. These they kindly supplied along with a reel of shielded multiple cored and individually numbered (for identification), cable to serve the multi-pin canon plugs we mentioned within last month’s update, that are located on the top of the engines.
The connector plugs for the electrical pumps however are no longer in production and are an unusual design, being a screw fitting that has two pins just above the centre line, so these had to be sourced from a supplier who fortunately still had some as ‘new old stock’.
The correct oil pressure gauges for the Viper jet engines are electrically driven and are somewhat unusual in respect of they read full scale deflection (40psi), with no power to the gauge. They then revert to zero upon engine start sequence prior to reading the correct oil pressure once the engine is running. Whilst there were many old stock 40psi aircraft oil gauges on the second hand market, everyone we looked at was reading zero with no power and therefore unsuitable for our application. Another treasure hunt was required to resolve this little puzzle but we got there in the end:
Last month we revealed the start of the next task which was cutting to size and then forming the scarf joints to the marine grade plywood kindly supplied by our sponsor Robbins Timber, for the sides to the hull of Longbow.
When it comes to attaching these plywood sections into place they need to be held in place whilst the West System Epoxy from our sponsor Wessex Resins cures. We were about to do this using a combination of metal screws, nails and staples when we were approached by Utility Composites Inc from the USA, who manufacture Raptor® composite nails and staples, that amongst other applications have been used with great success by boat builders.
There are several advantages to using these composite materials such as unlike their metal counterparts they can be sanded, they will never corrode, are UV resistant, have a high tensile strength and as they are driven into the wood they slightly melt forming a bond to the substrate. It is a fantastic unique product that we were totally unaware of, not having seen anything similar here in the UK. Pam Tucker and Cheri Clemons of Raptor® could not have been more helpful and enthusiastic for our venture with their support, even sending us the appropriate nail and staple air guns that you can see Steve using in the photo below after Fred coated the plywood with West System Epoxy prior to adding a layer thickened with 403 microfibre filler.
They do say that when boat building you can never have enough clamps which we can certainly vouch for as shown in the following photograph. These rugged reversible ‘F’ type clamps as you can see from our sponsor Sealey, really are superbly made, handling everything we continue to throw at them throughout the build without slippage.
That is it for this month’s update folks. We could perhaps have shown some more with regards to the progress with Longbow but thought this time around we would focus on the feedback from Dave’s latest round of tests with Spirit of Australia II and the current news regarding the historic jet hydroplane Crusader K6 from Steve, which we hoped you enjoyed reading.
Thank you for tuning in, if you have not done so already, please take a moment to like our Facebook page and we hope to see you again towards the end of October for the next instalment of this British attempt upon the Outright World Water Speed Record.
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