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Post by racket on Jun 24, 2023 18:23:00 GMT -5
Hi Chris Temp the other day was 17 C and humidity would have been ~50 - 60% at late morning when the test was conducted , just a normal winters day . A coupla pics of the jetpipe innards Thermocoupes and P4t pitot are at ~20-25 mm from the wall so as to be in the main gas stream , I try to position the thermos the same distance out so as to hopefully measure similar temps , the last test results were pretty good with not a lot of variation , well withing reasonable limits . Yep , next test will be interesting as the nozzle diameter is getting a bit tight, , hopefully the extra surge slot width will help with spoolup by dumping more air and aiding the aero into the wheel . The P4t pitot is only a section of 3/16"tubing bent at 90 degrees , probably not the most accurate device but it does provide a "number" which over the years has proved to be good enough for rough calcs . Cheers John
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Post by racket on Jun 25, 2023 22:11:54 GMT -5
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Post by racket on Jun 26, 2023 4:37:58 GMT -5
Hi Guys
Nearly another 30 lbs of thrust :-)
But with extra temps :-(
She was "chuffing" like a steam train when I throttled back from high power , might need more surge slot area .
A good test run overall , nice clean start and the new manometer mounts made for more accurate readings .
It seems I've got a bit of vacuum at the surge slot at max power , might need to reduce the IGV angle some more or even remove them if I open up the surge slot by another millimeter or two .
I'll collect all the numbers tomorrow and compare with last test
Cheers John
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Post by racket on Jun 27, 2023 2:23:20 GMT -5
Hi Guys
It looks like I had a tad more pressure in the jetpipe over the entire range , temps up by 50 C degs or so , but a lot more air being dumped at the surge slot according to the red manometer , worst at low power settings but improving as we went up the power range , with something strange going on between 2 and 3 Bar P2 , lots more "vacuum"at the comp inlet and an increase in surge slot dumpage , the comp inducer was biting off more air..
At full power the "vacuum "at the comp face of ~1360 mm of water represents a pretty high inlet velocity , a drop of a couple of psi static pressure and 11.5 C degrees .
I'll wait until my new 200 kg spring balance arrives before doing another test run , so I can verify whether or not theres an issue with the load cell readings when the engine is operating , its OK when static tested .
Cheers John
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dieselguy86
Veteran Member
Joined: September 2014
Posts: 186
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Post by dieselguy86 on Jun 27, 2023 7:28:05 GMT -5
Hi John,
Between your 2 and 3 bar, could that be where the inlet air is "lining up" with the blade inlet angle?
If it was further downstream, it wouldn't be showing up in the surge slot. Only thing that makes sense in my mind, is the rpms, blade angle, and incidence are all agreeing with each other in that range.
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Post by racket on Jun 27, 2023 18:55:30 GMT -5
Hi Joe
Yep , something must have "aligned" ..................I don't think theres much more I can do with the engine in its present configuration , it really needs a higher flowing turb wheel to take advantage of the comps potential , but then I'd need to redo the diffuser , then the flametube etc etc :-( ...............LOL, another build , no no no !!!
It was "interesting"when I throttled back , the whole test stand was gently pulsing, I don't know why as it settled down after a while .
This comp wheel has be a learning experience .
Cheers John
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bigkwaka
Member
Joined: August 2010
Posts: 11
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Post by bigkwaka on Jun 28, 2023 0:11:18 GMT -5
Hi Joe Yep , something must have "aligned" ..................I don't think theres much more I can do with the engine in its present configuration , it really needs a higher flowing turb wheel to take advantage of the comps potential , but then I'd need to redo the diffuser , then the flametube etc etc :-( ...............LOL, another build , no no no !!! It was "interesting"when I throttled back , the whole test stand was gently pulsing, I don't know why as it settled down after a while . This comp wheel has be a learning experience . Cheers John Hi John, Is there a “Higher flowing turb wheel” that fits the bill? Regards
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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 Jun 28, 2023 1:07:26 GMT -5
Hi John,
those are interesting findings!
thanks Ralph
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Post by racket on Jun 28, 2023 2:09:30 GMT -5
If only there was a suitable turb wheel , there isn't much choice at these sizes :-(
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Post by racket on Jun 28, 2023 2:11:54 GMT -5
Hi Ralph
Hope you enjoyed the videos :-)
Yep , the manometer readings are interesting as they show how things change at that critical position
Cheers John
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Post by stoffe64 on Jun 28, 2023 5:17:48 GMT -5
This is VERY interesting!, John are you going to install the afterburner now OR is that idea No Good idea? Would this be able to be used in lightweight homebuilt aircraft? Cheers/Stephan
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Post by racket on Jun 28, 2023 16:52:14 GMT -5
Hi Stephan
Afterburner will be re installed at some stage .
Yep , lightweight experimental class
Cheers John
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Post by racket on Jul 3, 2023 4:06:28 GMT -5
Hi Guys
The 200 kg spring balance arrived in the Post today :-)
Got 20 liters of kero to make up a new brew .
And will endevour to increase my oil pressure by packing up the pressure relief valve a tad .
Might make up a camera mount to video the spring balance before the next test , hopefully later in the week
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 Jul 4, 2023 1:27:47 GMT -5
Hi John,
let me sponsor some kero for your tests.
Cheers 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 Jul 6, 2023 1:55:49 GMT -5
Hi John,
I'm sorry, I forgot that you've already declined a support from me.
I am already looking forward to the next test run.
Cheers Ralph
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