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Post by smithy1 on Aug 21, 2014 14:49:51 GMT -5
Hi Brett, Thanks for the photos, good to see this beast again :-) Hope you have a good run on Sunday. Cheers, Mark. Thanks for the kind words Mark....Will do my best on Sunday  . I've changed a few things since I last ran the engine a few weeks ago, so I'll need to give the "Beast" a good looking at/check over prior to the first spool-up. Hopefully if Andrew is able to come along he can cast his eyeballs over things to make sure all is as safe as possible...the more eyes the better I guess. Cheers, Smithy. |
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Post by smithy1 on Aug 21, 2014 15:14:31 GMT -5
Nice setup, what are you using as a hot streak timer? Hi Richard, I'm not using a timer as such, just a momentary switch under my right thumb. The A/B activation switch, (on the left in the pic) and hot streak solenoid switch, (on the right) are independent of each other, I like to have control of things as much as possible . This way I can have some nice white clouds of unburnt A/B fuel if I so choose...  I plan to fit a second solenoid in the hot-streak fuel line for redundancy in the not too distant future. John has fitted a P2 dependent isolation switch which will not allow power to the A/B fuel pump unless P2 is above a pre-set pressure, (a pretty good idea really), I have essentially by-passed it and this will allow me to activate the A/B pump at any P2/rpm, I mainly did this to give me access to a nice big fluffy flame for car show purposes....looks impressive but does absolutely nothing for thrust augmentation..  Just hoping my hot streak will work as intended  .....the plumbing is a bit untidy at the moment, once I can be certain it works as designed, I'll set about cleaning things up a bit. On a side note....I've ordered and will be fitting a non-return/check valve to the A/B fuel line, this will stop any residual exhaust pipe pressure pushing the fuel in the line back through the pump and into the tank when the A/B is not operating....I had similar issues with my little 1/4 scale dragster, when the engine was running I could physically see the fuel running back through the A/B lines and pumps... and blowing bubbles in the tank...  , of course, next time you hit the A/B nothing happens because the pump is now suffering from cavitation..! All fixed with a simple check valve. Cheers, Smithy. |
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Post by Richard OConnell on Aug 21, 2014 16:43:00 GMT -5
If you want a timer somewhere down the line as a safety measure to keep the hot streak from running too long just let me know  Its never a bad idea in case something stops working as planned. |
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Post by smithy1 on Aug 21, 2014 18:56:42 GMT -5
If you want a timer somewhere down the line as a safety measure to keep the hot streak from running too long just let me know Its never a bad idea in case something stops working as planned. I might take you up on that Richard.....both the A/B and hot streak switches are momentary... so I can't forget to turn them off , mind you there's no guarantee they can't fail at some point. Cheers, Smithy. |
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Post by turbochris on Aug 24, 2014 13:17:49 GMT -5
don't forget to let go of the hot streak button! Push button NGV burnout! Use a timer!
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Post by smithy1 on Aug 24, 2014 15:24:27 GMT -5
don't forget to let go of the hot streak button! Push button NGV burnout! Use a timer! Hey Chris, LOL.....I'm well aware of the "melting turbine button" , I have the same setup on my little jet dragster, I have a little experience of driving real jet cars too, have done a few "slow-ish" passes in a Westinghouse J-34 & P&W J-60 powered machines a few years ago. I will most likely fit a timer once I get everything sorted and plumbed in correctly. Cheers, Smithy. |
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Post by smithy1 on Aug 24, 2014 15:28:34 GMT -5
Big thanks to Andrew, (enginewhisperer), and his lovely missus, (I'm afraid I've already forgotten her name??), for taking the time to come out and give me a hand to start the "Green Beast" yesterday, she started and performed nicely, all pressures and temps were in the "green" zone....although the EGT seemed a bit on the low side..! My hot streak experiment unfortunately was a bit of a dud, we suspect that the flame front in the CC didn't extend into the tertiary area which is where I had the hot streak nozzle. Needless to say, all I did was spray everyone with clouds of white Jet-A1 smoke  . I have a video which I will hopefully get up on Vimeo soon. I'm going to "re-plumb" the hot streak further up into the primary or secondary area and see how she goes, I'll then setup the second Bosch 044 fuel pump in the system to try and get this issue sorted....if this is the only problem I've got...I can't complain too much . john, I had a small issue with the ignitor plug, I had previously been getting intermittent spark, so I pulled the plug and checked it, plug ok, plug lead ok, ignitor module ok, seems the plug cap itself is dead, it has the 5kohm resistor and I think it might have given up the ghost....no continuity through the cap  , so I just connected the lead directly to the plug and the problem went away..! Cheers, Smithy. |
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Post by racket on Aug 24, 2014 17:15:32 GMT -5
Hi Smithy
OH NO ......not the plug cap .........bugger ;-)
Mmmmm , interesting that the hot streak didn't ignite , I guess the evaporators are doing their job and combustion is all in the top of the flametube ..............could you post a few pics of her insides when you next have her down for mods , I'd be interested to see how things look as I never had the engine apart after firing her up for the first time.
I hope the "audience" was suitably interested ..............looking forward to the video :-)
Cheers
John
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Post by smithy1 on Aug 24, 2014 17:26:59 GMT -5
Hi John, I think your evap tubes and combustion chamber are too damn good, it slowly became obvious to us that there wasn't any flame front down in the tertiary zone as the hot streak would've worked fine otherwise. Will carry out the necessary mods in the next couple of days after work. Will definitely take some pics of the innards while I have the lid off, from memory there was no heat distress to speak of as I didn't note anything amiss when I fitted the hot streak nozzle last week. Come to think of it, I only noticed slight coloration of the upper chamber, so yes, you're probably right, all the fire is happening very early, as it should. So I'll blame you for my hot streak not working..LOL I'll use the same nozzle insertion point on the outer chamber and just run the line outside the flame tube and have it entering further up into the primary zone.... My new "dual" Bosch 044 pump bracket has just arrived so I'll set about fitting all the required gubbins and plumbing while I'm fiddling with the hot streak. I was also interested to note the EGT during yesterdays run, it was quite low.... in the 380-390c range at idle , this had Andrew and myself raising an eyebrow or two... whereas last fire up she was ~460c, 380-390c seems a bit on the cool side to me, I might check the thermocouple calibration and see if the probe insertion length is consistent, but I can't see that being the issue...can't hurt to check I guess. Both readings were the same across both thermocouples, redundancy is a wonderful thing. As you're aware, I have some "contacts" at Sydney Dragway and I might see if I can organize to take the beast out to the track to at least do some engine testing in the large paved carpark. Cheers, Smithy. |
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Post by racket on Aug 24, 2014 18:26:01 GMT -5
Hi Smithy
Blame accepted :-) ..............she is a fairly long flametube compared to "micro" type engines , I was aiming for a "no hassles" flametube.
Would there be any potential vibrational fatigue problems with an extended hot streak line ?? .............I guess a few bits of lockwire holding it firmly against the flametube should solve any "fluttering" in the airflow .
Sub 400C is kinda low , maybe new batteries ( 4 X AAA size) required in the unit, I just had to replace the ones in my test stand unit,....I'm getting it operational for FM-1.
LOL.....Will those "engine tests" be with a driver in the seat ;-)
Cheers
John
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Post by smithy1 on Aug 24, 2014 18:41:35 GMT -5
Hi John, A "No Hassles" flametube..?? You've made it so well it's become a pain in the ar$e....thanks for that ya bastard..!LOL I fitted some new batteries to the EGT gauge just last week... had to clean up the contacts as they were a tad untidy...my fault though..left them in there too long. I don't forsee any vibrational fatigue issues, combustion sounds super smooth to me and I'm sure Andrew would agree there's not much in the way of perceived "flutter". I'm using a nice -4 stainless fuel tube from one of our RR Allison-250-C20B engines for the internal hot streak line, nice thick walled items they are too, all I've done is fit a 0.040" orifice to the end of it, I tested it with water and it squirts nicely with little or no spray as such, just a straight jet, exactly how I want it. Yep, I have some nice 0.025" inconel lockwire for just such an occasion too.. I'll be doing the driving duties at the track for sure, want to get the A/B running sweetly before I do anything silly, will be taking it nice and easy until I get my head around how it handles, brakes and steers etc......I fit nicely in the seat now too..! You wouldn't know where I could purchase caliper repair kits and brake pads for the front calipers would you?? Cheers, Smithy. |
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Post by racket on Aug 24, 2014 19:33:30 GMT -5
Hi Smithy
Nice solid tube for the hotstreak , no worries .
LOL...........if you can fit in that seat, you have slimmed down a tad ;-)
Ah, front brakes , now getting parts might be an issue , I did a fair bit of work on them to just get them into some sort of working condition, they'd been horribly abused by someone "paddock bashing" the kart.............they're a reputable brand of brake , so there might be bits available .
Most of the afterburning DIY turbine karts only have a single back brake which seem to be all they need , having fronts as well was more of an "insurance" issue for me rather than a "pulling up in time" thing , I found having 4 wheel braking on my earlier 2 shaft kart was a bit of overkill for our style of driving , probably needed when originally on a twisty racetrack where the extra bit of retardation could have meant the difference between winning or losing..............also the Class they run in can be pulling some pretty high speeds approaching 200ks , pulling the kart down from those speeds for a tight bend would need all the brakes you could muster.
Cheers
John
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Post by smithy1 on Aug 24, 2014 19:58:34 GMT -5
Yeah I hear you....the brakes still work ok, I was just thinking ahead...One of the front brake pads is looking a little ordinary and the pad material is coming away from the backing plate. What I could do is, modify one of my motorcycle pads to suit, that should see it sorted.
Yes I have "slimmed down" a tad, was close to 110kg's ~12 months ago... am now just over 95kg's, feel much better for it too, although loosing weight doesn't make me any prettier..! I've still got a head like a smacked ar$e ;-)
Cheers,
Smithy.
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Post by enginewhisperer on Aug 24, 2014 22:25:26 GMT -5
Thanks for the good day Smithy! I got a bit of video of the dragster - but my phone seemed to mainly pick up interference from the radio gear! youtu.be/Z3fOfLmAndQThe other theory we had with the hot streak is that since it's teed off the AB fuel line, maybe when there's higher P2 pressure there's not enough AB fuel pressure to flow enough in for the hot streak. It could be a combination of that and the lack of fire that far down the combustor It's probably worth testing it with the separate hot streak fuel pump first - and then moving the injection point further up if necessary. It certainly makes plenty of white smoke, so the AB was getting fuel! |
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Post by smithy1 on Aug 25, 2014 3:06:42 GMT -5
Hi Andrew,
You could be right, although at idle the P2 is only ~5psig and the A/B pump will easily overcome that. I still think the tertiary zone is pretty much devoid of flames in this situation..we'll soon find out I guess.
Cheers,
Smithy.
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I plan to fit a second solenoid in the hot-streak fuel line for redundancy in the not too distant future.
Just hoping my hot streak will work as intended 
.....the plumbing is a bit untidy at the moment, once I can be certain it works as designed, I'll set about cleaning things up a bit.
, of course, next time you hit the A/B nothing happens because the pump is now suffering from cavitation..! All fixed with a simple check valve. 
Its never a bad idea in case something stops working as planned.
. I have a video which I will hopefully get up on Vimeo soon.
, so I just connected the lead directly to the plug and the problem went away..! 
