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Post by Johansson on Aug 25, 2017 16:03:51 GMT -5
tanks Anders, now I understand how this works, its something i need to see before I see if I can make mine. it would be nice if a pressure sensor can be added to automatically switch the oil scavenge pump on and off. Nahh, just let the pump run all the time. A pressure sensor is just another piece of electronics that will eventually break down and cause problems. |
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Post by Johansson on Aug 23, 2017 14:21:11 GMT -5
John and Anders, What is the purpose of the scavenge pump if it is being bypassed by the check valve during operation? If the pump only becomes effective after shut down, why is it needed? Thanks, Tony Hi Tony, The scavenge pump is needed during low boost running and pre/post running. During one of my test rig runs with JU-01 I measured the pressure in the scavenge line and it was linear with the P2 pressure but aprox. 1 bar lower, so when the engine passed 1 bar P2 the pressure in the bearing tunnel was above atmospheric. This is when the one way bypass starts to work, it will let the air pressure in the bearing tunnel push oil out of the engine past the already maxed out scavenge pump and into the oil tank. Without it the scavenge pump would restrict the scavenge oil which causes the pressure buildup. Cheers! /Anders |
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Post by Johansson on Aug 22, 2017 23:01:30 GMT -5
Here are some pics of the check valve I made for my JU-01 return, I use it in parallel with a single scavenge pump and so far it seems to work perfectly.    Cheers! /Anders |
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Post by Johansson on Aug 22, 2017 14:28:54 GMT -5
That sounds like a pretty complex system, I vote for keeping it simple and not add any more valves and stuff than absolutely needed. The syringes shouldn´t get blocked if everything is working properly.
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Post by Johansson on Aug 21, 2017 14:32:39 GMT -5
That leaf blower should do the trick, we have a 3kW blower as well and I have even started the big JU-02 with it.
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Post by Johansson on Aug 20, 2017 23:05:18 GMT -5
Hi John, They were very satisfied with the visit, I held a short lecture on how gas turbines works first so they would know how everything worked together and "why the exhaust won´t melt the rear tyre" which is a painfully common youtube comment.  I just hope that the weather will be fine, even the slightest drizzle of rain will hold off the race so for once this crappy summer the sun could decide to shine on us. Cheers! /Anders |
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Post by Johansson on Aug 20, 2017 15:07:12 GMT -5
I think that the fuel coil is a bad idea, at shutdown all of the fuel trapped in the copper coil will start to boil and cause flames and soot inside the engine. Possibly even cause occasional syringe blockages just as Tony mentioned. You are doing great progress with your engine, when the oil leaks are fixed it will run like a pro! Cheers! /Anders |
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Post by Johansson on Aug 20, 2017 12:38:08 GMT -5
I was visited today by a jolly bunch of vintage motorcycle riders, they have an annual meeting and this year it happened to be near my place so they booked a jet show.  It was a very good opportunity to test the bike a final time before One Mile, it started perfectly and idled at ok temps so I am very satisfied with it! I didn´t take any video of the start but some of the bikers did so I´ll link the video here if any of them post it on internet. Cheers! /Anders |
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Post by Johansson on Aug 20, 2017 0:49:44 GMT -5
Congratulations!!!
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Post by Johansson on Aug 18, 2017 5:10:10 GMT -5
You really want to get a new off shelf compressor wheel since I know from experience that they are easily damaged during the gas producer R&D. It wouldn´t be fun buying a cheap used compressor and spend years designing an engine around it only to find that you can´t find a replacement wheel when some dirt has been sucked into it and damaged the blades beyond repair... /Anders |
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Post by Johansson on Aug 8, 2017 12:01:23 GMT -5
I printed a little hat for the preheat fan last night, I fear that the small 12v fan might get spun by the passing 300km/h wind and shed its blades into the compressor intake without it...  Cheers! /Anders |
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Post by Johansson on Aug 7, 2017 15:33:04 GMT -5
Nice work! |
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Post by Johansson on Aug 7, 2017 3:30:02 GMT -5
Hi Anders Full flow , 1 lpm - 1 kg/min isn't a lot compared to the 75 kgs/min of air ...............variable flow rates are just another thing to go wrong , or forget to readjust at a critical time. Cheers John Copy that, I have the water pump wired so that the micro switch in the trottle grip activates it. This will give full water flow the second I start trottling the engine up from 0.8bar which is the idle P2 setting, but as I will be revving the engine up quite fast I hope it will keep from drowning during those critical seconds up to full P2. |
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Post by Johansson on Aug 7, 2017 0:48:14 GMT -5
I am a bit confused about the oil vapor running, it takes plenty of fuel to run a turbine of that size until it grenades so I somehow doubt that some ingested oil smoke would be enough. Was the compressor shaft oil seal leaking so bad that it got oil into the combustor that way?
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Post by Johansson on Aug 7, 2017 0:31:39 GMT -5
Bugger! If you had a piece of plywood or any other flat and hard material you could have plugged the compressor intake and choked the engine, this would have extinguished the combustor effectively stopping the engine.  |
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