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Post by Johansson on May 19, 2012 6:48:43 GMT -5
I tested the oil system today and it seems to work fine, a nice and steady 5 bar oil pressure and the scavange pumps holds a 0.3 bar underpressure in the return line. It will be interesting to see how close to 0 it gets once P2 air starts to bleed into the bearing system.
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Post by Johansson on May 20, 2012 14:17:24 GMT -5
Olov and I made an effort to sort out the rev counter today, we have had lots of trouble getting the trigger signal strong enough for the rev counter to "feel" it but after building a signal enhancing circuit and using a laser transmitter it seems to work. Yours truly testing the rev counter on a piece of paper taped to the mill head rotating at 1000rpm. Just before we called it an evening Olov started to solder the parts to a circuit board, a couple of hours more and it will hopefully be finished. Cheers! /Anders
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Post by Johansson on May 23, 2012 16:20:22 GMT -5
Today I went by Olov and picked up the finished rev counter, it still needs a box and some more practical cables but it´ll do for the test run. I made a small aluminum bracket for the laser module and reciever diode. After bending it so the laser hits the white mark on the comp wheel inducer tip (it was painted on for rev counting during balancing) I torqued the bracket down and hit the light. I even managed to make a short video of the rev counter test, you can clearly see that the TV94 bearings are extremely sluggish at full oil pressure from the fast deceleration of the turbine shaft once the starting air is shut off. My next task is to source a jug of kerosine and set a date for the next run of JU-01! Cheers! /Anders
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Post by racket on May 23, 2012 18:09:11 GMT -5
Hi Anders
Neat :-)
Nice strong bracket on the laser pickup ,...............LOL, you worried about it getting sucked into the comp ;-)
Yep, time to buy some kero and light the fire .
Cheers John
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ashpowers
Veteran Member
Joined: February 2011
Posts: 207
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Post by ashpowers on May 23, 2012 19:51:25 GMT -5
Very nice, Anders! Mind telling us what laser and phototransistor combo you used? Setup looks great! =)
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Post by ernie wrenn on May 23, 2012 20:54:40 GMT -5
Love the tach setup...... Tell us more (how to build)
ernie
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Post by Johansson on May 23, 2012 23:54:15 GMT -5
Thanks guys! I say this on Olovs behalf since my contribution to the circuit board construction was to make coffee and stare incomprehensibly on what he was doing. ;D I´ll ask him for the specs on the laser and phototransistor and post the wiring diagram here after the weekend, will head off to the coast to see my brother and down a few cold ones tonight.
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ashpowers
Veteran Member
Joined: February 2011
Posts: 207
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Post by ashpowers on May 27, 2012 21:18:27 GMT -5
3,2,1 ? =)
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Post by Johansson on May 27, 2012 23:07:41 GMT -5
Counting down to the rev counter release? I asked him yesterday and he wants to make a new and better drawing of the wiring diagram with part numbers for everything etc. since the one he made for himself is a rather crude one with explanations in Swedish written all over it and lots of strange looking symbols for the parts... He´s a busy guy so please have some patience with him, he´ll get to it eventually. Cheers! /Anders
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ashpowers
Veteran Member
Joined: February 2011
Posts: 207
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Post by ashpowers on May 28, 2012 0:31:06 GMT -5
Hi Anders,
That was a countdown for your next turbine run test! =) I'm in no hurry for the tach - I've got plenty to do before I need it!
-Ash
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Post by Johansson on May 28, 2012 4:45:18 GMT -5
Aha, I see. =)
I have some work around the house and a driveshaft repair on my car to get done before I can start the JU-01 up, but if Olov has time to assist me I should be able to give her a spin this weekend.
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Post by turbochris on May 28, 2012 9:05:59 GMT -5
what did the signal look like on the o-scope?
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Post by Johansson on May 28, 2012 15:25:01 GMT -5
It comes as a square wave, we use a component called a comparator that takes a small voltage difference (like a weak signal from a laser/phototransistor setup for a gas turbine) and transform it to a strong signal/large voltage difference. en.wikipedia.org/wiki/Comparator
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Post by Johansson on Jun 3, 2012 2:39:26 GMT -5
Yesterdays test went well, unfortunately the rev counter didn´t work in daylight so after a couple of attempts to shield it I thought fuck it and ran the engine anyway. Dinner was fast approaching so we didn´t have time for any heavier modifications. She performed well and got up to 2.6 bar P2 before the fuel pump started to have problems flowing enough fuel, the jet pipe pressure gauge showed 0.55bar and the TOT was just above 700°C so it should be possible to get more power out of her later. We measured a thrust of 45kg at only 2.2bar P2, at that point the test bench started to tip over so with me and Linus holding the bench down any further thrust readings were sort of pointless. I think this test will end the pure jet development, I am in desperate need of my welding bench and I don´t think there is any reason to do any more test runs at this point. I really want to start constructing things again since there has been little done on that account after the engine tests began, now I can make the bike accessories and start on the power turbine section! Hooray! ;D Cheers my friends! /Anders
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Post by Richard OConnell on Jun 3, 2012 3:39:04 GMT -5
Very nice. Although it would be interesting to see where the performance of this engine is peaking at, I also tend to live on a bit on the boring, less wild side. 700 isnt a bad temp, but I wouldn't push it. You have a very good thing going for you and I am very impresed with your work, but I would hate to see something go wrong. I think this marks an excellent stopping point for your project and it deserves a huge congratulations from anyone who has had the pleasure of following this thread There is of course room for higher power, but that seems like it is serving as a nice comfort barrier for the time. -Richard
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