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Post by Johansson on Mar 24, 2015 3:03:22 GMT -5
Hi John, Oil pressure has actually been a bit unstable and somewhat related to how the engine is run, running the pump with the gas turbine shut down or idling can produce a pressure of 3.5kg but once the P2 is raised and the afterburner lit the oil pressure seems to increase towards 4-5kg. The test you suggested sounds logical, I´ll tell Olov about it next time we meet. I will ask him to measure the amount of oil in the tank, the 4L I said earlier was my estimation so it might be a bit more in reality. The oil tank is a round helium tank roughly filled to 1/2 with oil, here it is during construction: Cheers! /Anders
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Post by racket on Mar 24, 2015 3:56:52 GMT -5
Hi Anders
Its interesting that the oil pressure increases with P2 and A/B activation , could the oil tank breather be the problem ??
Higher P2 will increase blowby past the seals , if the tank breather is restrictive the air pressure in the tank goes up forcing more oil into the pump if theres also a restrictive suction line and/or cold oil, which then increases oil pressure.
If I was setting up this oil supply, especially for your cold weather operation, I think I'd be using a 25mm ID suction line between tank and pump and 15mm ID out to a Tee piece with 10mm ID lines to each turbo............LOL, I've always had a fear of starving my turbos of oil so tend to over engineer the system to be on the safe side .........I'd like to see Olovs system capable of supplying 20 litres/minute.
The suction side can produce as sort of "cavitation" effect with cold heavily aerated oil flowing through a marginally sized suction pipe.
I hope you guys can get this minor problem sorted as the kick has such huge potential, I wanna see it perform to its best :-)
Cheers John
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Post by Johansson on Mar 25, 2015 2:51:31 GMT -5
Hi John, The oil tank breather is a 20mm ID hose so no restrictions there. The oil pressure lines are 12mm ID at a minimum and has a massive flow thanks to the hydraulic pump, so I don´t think there is any risk of starving the turbos of oil. If the weather holds Olov will do another test run this weekend, he´ll try to fill more oil in the tank and see if that improves things. It would be very satisfying to get a 160km/h run out of the kick before we put it away for the summer. Cheers! /Anders
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Post by racket on Mar 25, 2015 3:17:24 GMT -5
Hi Anders
Bummer , this is gunna be a hard one to fix as Olov has already designed out the usual "problems" :-(
All the best with the next run
Cheers John
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Post by Johansson on Mar 25, 2015 3:41:42 GMT -5
Hi Anders Bummer , this is gunna be a hard one to fix as Olov has already designed out the usual "problems" :-( All the best with the next run Cheers John Hi John, It might be as simple as that the oil is slung backwards during acceleration and bacause of the low oil level the oil pickups at the bottom of the tank starts sucking a vortex until air is ingested. The large flow capacity might actually be causing this problem. Once the engine flames out the loss of acceleration makes the oil drop to the bottom of the tank and the pump starts sucking oil again. It will be interesting to see if the increased oil volume helps, if so the theory is confirmed. Cheers! /Anders
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Post by olovselander on Apr 4, 2015 4:03:40 GMT -5
Hi guys and thank you for all your support! As you may understand i´m "Olov" (the stubborn guy trying to do everything NOT the way Anders told him to ) The oil volume in the tank is almost 10 liters today (at least 7-8) so slightly more than Anders mentioned first, but still not enough thou. Anders came with the idea that we should plug the return lines from the pressure regulator directly to the pump suction line. That won´t help the volume issues but the flow from the oilpickup will be reduced and maybe the need of a bigger diameter suction line will be reduced. Also the possible vortex effect in the tank. At least when the oil is cold we have a masive flow in the tank lines from the regulator. And if pump capacity would be an issue we still have a lot of rev to go with the four stroke pump engine. It may be a good idea to plumb the regulator return lines with transparent hoses and make a static test to check how the regulator return flow is affected by the run time and oil temp. I will also to next year make a new regulator since the one we use now was made for the very first jetkick. I guess you haven´t even seen that one, at least i hope so! I didn´t even have a good lathe at the time so precision isn´t the best. It might be the regulator who´s not capable of closing enough when oil is thinned by the heat. Any way, we have some things to look at and all your input and ideas are highly appreciated! The good thing from the tests on the lake is that thrust seams to be much higher than on SpeedWeekend! Thanks! /Olov
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Post by pitciblackscotland on Apr 4, 2015 4:57:35 GMT -5
Hi Olov, Have you thought about using two separate oil pumps or a 2 stage hydraulic pump to feed each turbo Cheers, Mark.
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rythmnbls
Veteran Member
Joined: August 2011
Posts: 145
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Post by rythmnbls on Apr 4, 2015 7:46:53 GMT -5
Hi Olov, welcome to the site.
Looking forward to more jetkick successes at Speedweek.
Regards.
Steve.
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Post by olovselander on Apr 4, 2015 10:47:42 GMT -5
Mark: Actually i have one on the shelf but since we´ve talked about making a free turbine for´em and put´em in a boat later on i thought about taking the second stage for the free turbine/gearbox. And when we built the twin kick we just pulled the engine/pump unit out of the old one to save some time. The flow shouldn´t be a problem i think/hope. But maybe as i said earlier the return flow test make me have to change my mind on that. Thank you Steve, we´ll do our very best to make shure you will see some. Thanks! Olov
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Post by racket on Apr 4, 2015 18:46:08 GMT -5
Hi Olov
Great to see you here on the Forum :-)
I've heard lots about you from the many emails Anders and I have exchanged over the years .
Theres a lot of potential with your kick , just a few minor problems to sort out , same as with all builds whether by us DIY'ers or the professionals .
Yes , plumb the relief valves outflow back into the suction side of the pump , it'll save a lot of aeration problems with the oil in the tank , I normally use automotive oil pumps which have both filter and relief valves included in the one body , its probably helped with preventing potential lube problems as the oil recirculates within the pump with less being drawn from the tank.
LOL...............thrust would have been up by a huge margin once the jet nozzle diameter was reduced , just some minor tweaking of its diameter to get your TOT temperatures back up to optimum whilst burning your ideal amount of A/B fuel.
I'll be looking forward to hearing more of the kicks development, its a credit to you , you should be very proud of creating such a beautiful machine :-)
Cheers John
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Post by olovselander on Apr 5, 2015 4:05:53 GMT -5
Thank you very much John! TOT still is way too low if we should trust the k-type thermocouples. They both said around 650´c on the last lake tests. And about the A/B fuel amount it would be interesting to measure the flow to know if we´re in the box or not. The hole thing seems to run a little bit to cheap from what i thougt. Still the 044 pump copy runs at full speed for the A/B. Have a large ss bowl that i´ve had small plans to make a pressurized chamber of to flow test fuelnozzles with a simulated chamber pressure. Maybe with the new planned logging device we could also include som flowsensors for the fuel. Lots of fun ahead! Olov
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Post by racket on Apr 5, 2015 15:43:56 GMT -5
Hi Olov
I did some calculations for the twin kick engine some time back when Anders first mentioned it to me and I worked on a combined flow of ~3.3 lbs/sec - 1.5 kgs/sec with a T I T of ~900 C and a TOT of ~750 C , if running in one of your cold winters at 0 deg C you could be producing a 4:1 Pressure Ratio at ~86,000 rpm (indicated) with 3 bar P2 and ~0.75 Bar total pressure in the jetpipe measured with a pitot tube .
With 1.5kgs/sec air flow you'll be needing a total fuel flow of ~2.3 litres/min into the gas producer ( 2 X 1.15 lpm flows ) and ~5.7 litres per minute to the afterburner at full power , so ~8 litres per minute total fuel burn rate for the machine at full power ................thirsty bugger :-)
I think you'll be needing another 044 pump for the A/B as fuel burn efficiency isn't always that good , it can be a lot less than 100% , so you might need to be feeding 6 to 7 litres/min to the A/B
Yep , lotsa fun ahead :-)
Cheers John
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Post by Johansson on Apr 6, 2015 2:49:11 GMT -5
I wonder if the battery is capable of running four 044 pumps flat out.
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Post by olovselander on Apr 6, 2015 13:52:56 GMT -5
At least that´s something we figure out during our workshop testruns Thank´s John, great data! Here is a short onboard video from the lake testing. Not shure how to embed it.. www.youtube.com/watch?v=8_7U0yL70xcOlov
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Deleted
Joined: January 1970
Posts: 0
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Post by Deleted on Apr 6, 2015 14:08:04 GMT -5
Hi, the twin that Nick built that is now in the mini of Dan Goodwin has two 044 pumps teed together for both afterburners, and it could still handle more, so think two on your afterburner is a must
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