|
|
Post by racket on Sept 25, 2011 17:41:47 GMT -5
Hi Chris
LOL, .....................its as simple?? as I could make it ;-))
Fortunately the 6041 has a very strong compressor wheel , the map goes to a tip speed of ~1,900 ft/sec at ~78,000 rpm but best power is ~66-68,000 rpm , giving a 10,000 rpm buffer.
Mass flow doesn't increase much between 66,000 and 78,000 rpm due to inducer choking because of the 56 Trim wheel and efficiency falls off badly as well over that rpm range , so I'm thinking of using these "disadvantages" to negate the need for a variable jet nozzle area , ..................just wind her up to 70,000 rpm or so ( ~40psi P2 ) then hit the A/B switch , the rpm will then drop back into the more efficient region of 66-68,000 ( 35-37psi P2) and all will hopefully be well even in the event of an A/B flameout as the rpm will only climb back up to the initial setting ........................heh heh , that's the theory anyway , gotta wait until I can fire her up to find out if it works .
Cheers
John
|
|
|
|
Post by Johansson on Sept 27, 2011 4:30:20 GMT -5
A really neat sollution with the afterburner switch!  |
|
wolfdragon
Senior Member
Joined: April 2011
Posts: 287
|
Post by wolfdragon on Sept 27, 2011 6:55:47 GMT -5
Don't forget to charge up the camera
|
|
|
|
Post by racket on Sept 27, 2011 15:21:00 GMT -5
Hi Wolf
Yeh , the camera .................LOL. why do I have so many problems with the camera ..............just press button and it should work ............its not "rocket science" ...............mmmm , maybe thats the problem , I'm not good with "gadgets" ....................I'll try harder :-)
Cheers
John
|
|
|
|
Post by enginewhisperer on Sept 28, 2011 17:41:44 GMT -5
give me a yell when you're doing testing and I'll see if I can visit, with an extra camera and a set of earmuffs  |
|
|
|
Post by racket on Sept 28, 2011 20:03:58 GMT -5
Hi Andrew
Still trying to get the ignition electrodes for the A/B , I've been in contact with some people so hopefully soon , otherwise I'll be disassembling some spark plugs to use their ceramic bits .
Cheers
John
|
|
|
|
Post by enginewhisperer on Sept 29, 2011 2:56:11 GMT -5
keep me posted |
|
|
|
Post by ernie wrenn on Sept 29, 2011 16:34:31 GMT -5
racket
look at the spark plug for the torpedo oil heaters that are used on construction sites, they have long electrodes and grounding straps.
ernie
|
|
|
|
Post by ernie wrenn on Sept 29, 2011 16:37:03 GMT -5
|
|
|
|
Post by racket on Sept 29, 2011 21:30:38 GMT -5
Hi Ernie
Thanks for the Link ......................yep , some of those with the twin electrodes are whats needed , my biggest problems has more to do with what I can make to mount the electrodes into that can then be bolted and sealed against the red hot A/B wall some distance downstream from the flameholder , hopefully the electrodes I've ordered will do the job otherwise I'll be revisiting thing :-)
Cheers
John
|
|
|
|
Post by stoffe64 on Sept 30, 2011 0:28:40 GMT -5
John,you could also use the hot streak ignition method,have you considered that alternative?
|
|
|
|
Post by racket on Sept 30, 2011 1:15:15 GMT -5
Yep, considered that , but prefer to not stress the turbine wheel any more than it already is , also it would require pump , timer and plumbing to do it "correctly" , theres also the chances of things going wrong , guys have fried wheels from "dribbling" hot streaks , with a turb wheel costing >$1,000 I don't want to fry it , preferring the A/B bits to all be downstream of the gas producer .
Did some flow checks on the spray ring today , the EFI pump produces ~3.4 litres/min- 200 lph of kero thru the 16 X 1mm dia holes at very little pressure , so even with the several psi of gas pressure in the A/B , flow should be close to this figure .
The engine flows ~1.25 kgs/sec -75 kgs/min of air , so we'll need ~5 kgs/min of fuel overall , or ~6.25 lpm of kero , with the gas producer needing maybe 2 lpm that leaves ~4.25lpm for the A/B requirement ..................I might need an extra pump, but we'll see how she goes with this limited amount first :-)
Cheers
John
|
|
|
|
Post by racket on Oct 14, 2011 3:33:10 GMT -5
Hi Guys
Bit of an update on "progress??" .
Electrodes finally arrived a couple of days ago and were fitted to their mounting block which was then fitted to the A/B outer wall ~2 inches downstream of the flameholder , muffler putty used for sealing the mount to A/B
Leads were made and fitted between ignitor unit and electrodes , suitable high temp sheathing over the leads to minimise radiant heat problems .
Ignition on/off tested at the preset 28 psi P2 pressure ignition point , nice light inside the A/B , interesting how only one of the electrode metal bits gets hot , must be the "direction?" of the spark .
Plumbing between A/B fuel pump and spray ring made and fitted , with allowances for expansionary changes requiring sliding mounts for the stainless tubing .
She's all tanked up and ready for a test run tomorrow.......................yeh yeh , I'll remember the camera ;-)
Cheers
John
|
|
|
|
Post by stoffe64 on Oct 14, 2011 4:03:34 GMT -5
Nice work John,looking forward for the film to come,goodluck with the run tomorrow
|
|
|
|
Post by Johansson on Oct 14, 2011 5:27:37 GMT -5
Good luck John, can´t wait to see the engine running! |
|
