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Post by racket on Sept 14, 2023 2:58:28 GMT -5
Hi Ralph
Yep , I really should try to mount a tach .
My latest test run a couple of days ago didn't provide any new explanations of why theres no repeatability of results , it seems that each test run is different to the next , its very frustrating .
I get the feeling that the comp wheel with its "high"inducer tip angle of ~34 degrees is creating the inconsistencies , theres no way I can produce acceptable inducer velocity triangles :-(
I'll pull the engine apart again and have a look inside .
Cheers John
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Post by racket on Sept 19, 2023 4:07:27 GMT -5
Hi Ralph
Tach sorted , I can slip it into the starter spider once the engine is up to idle , comp snout and nut have been black and white painted and reflective tape added to the white side , hopefully it does the job :-)
Other mods ..............changed back to an earlier flametube used 18 months ago , and increased the diffuser exit area by removing ~6 mm off the alloy wall .
Engine reassembled , back on the test stand tomorrow .
Cheers John
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ripp
Veteran Member
I'm sorry, I don't speak english, so I torment you (and myself) with a translation program,Sorry
Joined: January 2013
Posts: 236
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Post by ripp on Sept 19, 2023 14:44:42 GMT -5
Hi John,
I hope there is an improvement and I'm looking forward to the video 🤞
Cheers Ralph
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Post by racket on Sept 22, 2023 22:43:59 GMT -5
Hi Ralph Something just for you :-) youtu.be/TKL2jUYtCvIThings were going well until a slight malfunction of the ignitor security :-( The old flametube seems to provide better temperatures , but will need to wait until I have the A/B fired up . Cheers John
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ripp
Veteran Member
I'm sorry, I don't speak english, so I torment you (and myself) with a translation program,Sorry
Joined: January 2013
Posts: 236
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Post by ripp on Sept 23, 2023 3:01:01 GMT -5
Hi John,
thank you! But you make it exciting!
52993 rpm, 2.7 par and the tachometer switches off
I'm excited to see what the values are at 3.5 par
thanks Ralph
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ripp
Veteran Member
I'm sorry, I don't speak english, so I torment you (and myself) with a translation program,Sorry
Joined: January 2013
Posts: 236
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Post by ripp on Sept 23, 2023 3:12:33 GMT -5
Hi John, is it this shape of combustion chamber? Cheers Ralph
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Post by racket on Sept 23, 2023 5:09:52 GMT -5
Hi Ralph I'm using this old flametube imgbb.com/6sSqyDf , jetandturbineowners.proboards.com/thread/1459/11-127-manned-flight-engine?page=26 it preceeded the one you posted a pic of, its not ideal as it has holes in less than ideal positions :-( I started running into problems today as I was approaching 3 Bar P2 , the whole test stand was starting to shake , I think its from turbulence within the afterburner when its not operating ,this has happened before. I'm not sure if it was the vibration that caused the tach to stop , or if it has a time limit of some sort , but the shaking then dislodged the ignitor leaving a 13mm diameter hole blasting out hot air which took me by surprise as this has never happened before . When I fitted the "new/old" flametube I made some changes to the ignitor mounting so that it protrudes deeper into the flametube to help ignition , which it appears to have done , but the fittings that hold the ignitor , a nut and olive , 1/2"copper pipe fittings , weren't compressing the olive sufficiently to crimp onto the ignitor body , I've since machined off another couple of millimeters from the nut so that it doesn't bottom out on the 1/2"BSP thread mating piece silver soldered into the outer can, the ignitor is now nicely secured :-) Hopefully the next testrun will be less "exciting" . The manometer readings were of interest to me as it appears more air was flowing through the engine than when the A/B is alight , I wanted to do a set of "dry "readings up to 3.5 Bar and then a set of "wet " readings to find how things change along with the RPM readings to give me an idea of how the air flow is behaving , but it looks like it might be difficult reaching 3.5 Bar during a dry run because of the vibration . RPM appear to be roughly what I had with the old Chinese compressor wheels at the various P2 readings, I need to do some research on P2 vs RPM vs tip speed to give me an idea where it would be flowing on an imaginary map :-) The weather was good today , hopefully it will stay that way so that I can get the numbers I need :-) Cheers John
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Post by racket on Sept 23, 2023 18:34:22 GMT -5
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Post by racket on Sept 24, 2023 3:40:39 GMT -5
Hi Guys Another test this afternoon with different result . She's dead :-( youtu.be/t4RFGaEmf9kCheers John
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Post by racket on Sept 24, 2023 4:23:41 GMT -5
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ripp
Veteran Member
I'm sorry, I don't speak english, so I torment you (and myself) with a translation program,Sorry
Joined: January 2013
Posts: 236
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Post by ripp on Sept 24, 2023 5:24:58 GMT -5
Damn what happened?
Ralph
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Post by pitciblackscotland on Sept 24, 2023 9:19:16 GMT -5
Hi Guys Another test this afternoon with different result . She's dead :-( youtu.be/t4RFGaEmf9kCheers John
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slittlewing
Senior Member
Joined: November 2017
Posts: 493
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Post by slittlewing on Sept 24, 2023 12:44:27 GMT -5
Hi John,
TOTs were already too high at 3 bar (875C?) but the final push was too much! How bad is the damage?
At least you aren’t injured which is the main thing! Lots of flames out of the back at the end!
Cheers
Scott
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praendy2203
Veteran Member
Joined: August 2020
Posts: 181
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Post by praendy2203 on Sept 24, 2023 15:35:49 GMT -5
Hi John,
This was the turbine wheel I think. It was a contained engine failure. Waiting for your diagnosis😫
Andy
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Post by racket on Sept 24, 2023 19:56:09 GMT -5
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