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Post by racket on Jan 17, 2023 19:48:33 GMT -5
Hi Guys
Went for a testrun this morning , oil tank preheated , the weather was OK , I was feeling ready , took my time setting up , had the load cell fitted and afterburner ready to fire for a full power test .
All went great until I tried to fire her up :-(
Couldn't get up to idle on the first try , and the second attempt was rather short as the starter motor decided to give off the "magic smoke "..............bummer , packed up and came home .
LOL.............some days are successes , others are failures ..............maybe next time :-)
Cheers John
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Post by madpatty on Jan 17, 2023 19:55:32 GMT -5
Hi Racket.
I totally understand what you may be feeling. Such is R&D. I’ve had my fair share of failures with my current engine.
But we have to keep going with this R&D as you always say.
Cheers Patty
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Post by racket on Jan 17, 2023 21:05:54 GMT -5
Hi Patty Yep , only perseverance will get us through . LOL , I checked the 3 camera batteries , the loadcell tablet battery , the two 12V car batteries for the starter and the deep cycle battery for the ancillaries , plus the various batteries in the thermometers ...........heh heh , they all worked flawlessly :-) Heres a short video on just another failure youtu.be/wzL52Au536k Cheers John
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Post by enginewhisperer on Jan 17, 2023 21:12:02 GMT -5
bummer! It looked like a nice relaxed setup until that point
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Post by racket on Jan 17, 2023 23:17:58 GMT -5
Hi Andrew
Yep , all was going well,..... LOL, maybe too well , the gremlins soon sorted that out ;-)
Cheers John
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Post by racket on Jan 18, 2023 0:37:29 GMT -5
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Post by racket on Jan 18, 2023 17:14:13 GMT -5
Hi Guys
Pulled the starter apart and it doesn't look very nice :-(
The brushes have been arcing badly and were stuck in their sliders , lotsa molten copper at the edges .
Mounted the armature in the lathe and skimmed the commutator , it looks OK , sort off :-)
Might see if I can cannibalise some brushes out of one of my "spare " motors .
It sorta explains my recent starting difficulties
Cheers John
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Post by racket on Jan 19, 2023 2:20:31 GMT -5
Hi Guys
Starter motor "fixed " , bit rough, but it happily spins the rotor :-)
Pinched a couple of carbon brushes from an old starter .
Cheers John
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Post by racket on Feb 4, 2023 2:43:58 GMT -5
Hi Guys
Have ever been in a situation where you "know" the " Gods " are against you :-(
I've been waiting weeks for everything to be "right "for a testrun , the starter had been test 10 times in the shed , running the rotor up without problems , but out at the test site for an actual fire up , it decided to die again :-(
LOL.....please , I just want one more test run .
Cheers John
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slittlewing
Senior Member
Joined: November 2017
Posts: 458
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Post by slittlewing on Feb 4, 2023 12:27:24 GMT -5
Sorry John, I’m sure the trials and tribulations will make eventual success even more enjoyable!
Cheers
Scott
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praendy2203
Veteran Member
Joined: August 2020
Posts: 160
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Post by praendy2203 on Feb 4, 2023 16:45:52 GMT -5
Hi John,
thats very sad😁
I some of your last videos I saw a leef blower for cooling down the engine. I guess the blower is not strong enough to spool the shaft. (Only for backup)
Next time try only 9 times, so you will have 1 try left😊
Good luck,
Andy
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Post by finiteparts on Feb 4, 2023 17:22:38 GMT -5
Your gas turbine engine R&D has somehow become a high speed starter R&D. I know the pain.
I worked on a small development engine that was using some exotic bearing tech, but the primary goal was to demonstrate this special little engine, which we anticipated to have some leanings of it's own that would need to be taken care of once we fired it up. Well, long story short, our engine became a bearing test rig for many test weeks. We finally had to swap out the "special" bearings for more standard stuff, just so we could get the little dude running.
Two laws from Akin's Laws of Spacecraft Design seem to apply:
3. “Design is an iterative process. The necessary number of iterations is one more than the number you have currently done. This is true at any point in time.”
39. "Any exploration program which “just happens” to include a new launch vehicle is, de facto, a launch vehicle program"
Our's was a de facto bearing development program!
Keep up the good fight!
-Chris
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Post by racket on Feb 4, 2023 19:16:29 GMT -5
Hi Chris
LOL.......very true :-)
I pulled her apart and found that my "mods "to the internal cabling were the problem , arcing melted the wiring onto the field coils :-(
Gotta find another starter , but am having problems as I can't seem to find what the original parts came from , so going back over my notes to find something .
If all else fails I'll go see my local "auto recycler ", they know everything :-)
Cheers John
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Post by racket on Feb 4, 2023 19:18:23 GMT -5
Hi Andy
Yep , only 9 times and I'd have been OK :-)
Nope blower not strong enough , I even purchased a big backpack blower earlier on to try , but it even failed to spool her up .
Cheers John
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Post by madpatty on Feb 4, 2023 23:29:02 GMT -5
Hi Racket.
Why don’t you try a brushless motor for the starter? I am using a leopard 5692 rated at max power of 5mw for my starter. I am using a hx82 rotor (98mm compressor with 112mm turbine) almost similar to your 10/98 engine and I am getting close to 18000 rpm dry during startup.
I am pretty sure there are more powerful bldc motors available out there suitable for your rotor size.
Regards Patty
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