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End of the Sprite project
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03-27-2014 | 03:29 AM
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Jgwright
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Norfolk , UNITED KINGDOM
End of the Sprite project
The end of the Sprite project
My winter project this year was to build up all the sets of parts I had for the Sprite into engines to reduce the number of boxes of parts lying about the house. Amazing how much more room the engines take when in bits!
Originally I had ideas of making the engine for sale but rapidly found that having a running engine and having a reliable engine that was simple to assemble is a totally different thing. In the years since making the first engines I have had to shorten the shaft and thicken it to remove shaft vibration. I had new shaft tunnels made from stainless steel to help protect the rear bearing which runs very close to the exhaust outlet. The compressors all needed modifying and new compressor nuts.
The most difficult thing to get right was the preload. With this particular engine design and the compressor the shaft moves differently under load and with no load. This took lots of time and experiments before finally devising a solution.
I now have 31 engines complete so should have a some good runners among them! I still have some mods to do to the older engines to get them to the same spec. Please don't mail me asking for engines, as I will not be selling them to the general public. Now all I need is a project that needs 31 engines with 100Kg thrust! Seriously I am now making up a Falcon 120 powered by 2 Sprites that I am converting to a flying wing. I shall post some info on how it is done and what the results are. My Arado will need its 6 engines that are now hopefully reliable so it can complete the LMA schedule.
The spec of the engines is unchanged. Thrust is 3.25 - 3.5 Kg at 250,000 rpm.
As you know this has morphed into Gaspars new Merlin 35. Gaspar has achieved what I struggled to achieve, a reliable engine that is simple to manufacture. The long wait will definitely be worth while. Every aspect of the engine has been looked at and often changed. The only thing that has remained constant is the spec, where Gaspar has the engine running with a slightly less high max rpm. This is very much a next generation engine especially the electronics.
John
Sprite on test
http://www.youtube.com/watch?v=ioBf4GAe8wU
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