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Post by racket on Oct 5, 2021 23:36:06 GMT -5
Hi Smithy
Ah yes , thats the thing , thanks for that :-)
Nice and "soft" for a better seal .
I'll keep persevering with the leafblower for a bit longer, at least until I get the ignition of fuel well sorted , just the usual things to "learn" with a new build .
How long does it normally take you to get the GT6041 spooled up ?? .............it'll give me a number to consider , its been so long, I've forgotten how a leafblower start behaves .
Cheers John
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Post by racket on Oct 6, 2021 19:51:08 GMT -5
Hi Guys
Did some flow vs pressure vs atomisation testing today .
With a delivery pressure of 4.5 psi ~1,000 ml/min went through the 9 X 19G bent tip injectors in the engine .............thats what drained out the combustor drain , test repeated a few times to be sure .
To test atomisation I fitted a tee piece into the delivery line and used a spare injector attached to the end of some 3/16" tubing .
Even at the modest pressure drop across the injector of only 4.5 psi , the fan spray was reasonable with good atomisation .
At a higher flow rate of ~1,600ml/min to better represent idling/low power conditions , the test injector with ~7.5 psi of pressure drop had excellent atomisation .
All looking good :-)
Cheers John
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Post by racket on Oct 13, 2021 22:18:26 GMT -5
Hi Guys It was time to improve the backpack blower's "compression" efficiency , so have added a shroud to it , no more bypassing around the blades . Just waiting for the silicone glue to cure and I'll give it a try . My small leafblower had a shroud fitted to it >20 years ago to enable starting of the TV84 bike engine , its still working OK :-) Cheers John
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Post by smithy1 on Oct 18, 2021 23:02:04 GMT -5
Hi Smithy Ah yes , thats the thing , thanks for that :-) Nice and "soft" for a better seal . I'll keep persevering with the leafblower for a bit longer, at least until I get the ignition of fuel well sorted , just the usual things to "learn" with a new build . How long does it normally take you to get the GT6041 spooled up ?? .............it'll give me a number to consider , its been so long, I've forgotten how a leafblower start behaves . Cheers John Hi John, Once light-off occurs.. I like to take things slow and steady watching for temp spikes. Plenty of blower helps.....I then chase it up with slow/steady increases in fuel till my idle setting of ~ 130psi fuel pressure, then I just open up the fuel supply tap fully as the throttle valve minimum flow setting now controls the fuel flow..... it usually takes a good 25 seconds or so to achieve a stable idle. I'd rather a slightly slower warm-ish start than a quicker hot one, less thermal stress on the hot bits. I try to limit max temp during start to ~800C...I know the inconel turbine wheel can handle 1000C for very short periods but I'd rather not go there. As you're well aware, the 6041 is a big heavy lump of a rotor to get spinning. Once up to idle she's happy to sit at just ~2-2.5 psi P2. Idle temps are usually in the mid 450C area. I have the max P2 limited via the max throttle stop to 42psi..... but achieving this often depends on the ambient air temp and altitude etc.. You may remember up in the mountains where you used to live.... it just wasn't possible. Cheers, Smithy.
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Post by racket on Oct 19, 2021 3:22:48 GMT -5
Hi Smithy
Thanks for the numbers , thats reassuring , I sorta remember now you mention it that the rotor was slower to accelerate than the TV94 ones because of the extra weight , and these TF15 ones are even heavier , so I'd better be content to have anything up to 30 seconds for spoolup :-(
I'm hopeful of some video this week of a successful start , if my long awaited screws arrive so that I can get the engine back on the test stand .
Thanks again :-)
Looks like you might be able to leave Qld by Christmas , or at least return ;-)
Cheers John
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Post by racket on Oct 21, 2021 18:39:25 GMT -5
Hi Guys
She's all tanked up , the oil heater is on , camera battery charged , hopefully this afternoon might just see her fired up .
LOL.....Just need to put my "big boy" pants on and find a coupla balls ;-)
Cheers John
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Post by pitciblackscotland on Oct 21, 2021 20:32:00 GMT -5
Good luck John Cheers, Mark.
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Post by madpatty on Oct 21, 2021 21:21:15 GMT -5
Good Luck Racket. 👍
Cheers
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Post by racket on Oct 21, 2021 22:06:53 GMT -5
Hi Guys
I found 1.5 balls , but it was enough :-)
She lives , video later, gotta stop shaking first , that wasn't good for my heart , its been playing up ever since the second Covid jab 2 months ago , I'm "sweating like a pig" and its only 23 deg C :-(
I'm happy , the fuel setting was a tad low during spoolup so needed a bit more to prevent a hung start, but that was the only complaint , otherwise it was a fairly straightforward spoolup .
She's a tad noisy even with an open pipe on her :-)
Cheers John
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Post by racket on Oct 21, 2021 22:43:50 GMT -5
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Post by pitciblackscotland on Oct 21, 2021 23:25:53 GMT -5
Hi John, Look like a nice easy start there Next time are you going to flex it's muscles Cheers, Mark.
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Post by racket on Oct 21, 2021 23:40:20 GMT -5
Hi Mark
Yep , I'll take it out to my test area where the noise won't be a problem and I can extend the run time and take some proper numbers, this was only to see if it fired up .
Temps were only ~500C so thats good :-) a jetnozzle needed .
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: 231
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Post by ripp on Oct 21, 2021 23:52:24 GMT -5
My Congratulations
Ralph
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Post by racket on Oct 22, 2021 0:33:20 GMT -5
Hi Ralph
Thanks for that , much appreciated :-)
Cheers John
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Post by andym on Oct 22, 2021 0:37:31 GMT -5
Hi John WoW..... nice clean spool.... wonderful... All The Best Andy
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