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Post by turbochris on Dec 13, 2011 12:50:02 GMT -5
Smithy, how are you hot streaking your jet dragster?
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smithy
Member
Joined: August 2010
Posts: 31
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Post by smithy on Dec 18, 2011 17:26:50 GMT -5
Smithy, how are you hot streaking your jet dragster? Hey Chris, Pretty much the same way as a normal jet dragster engine, I just have a fine shot of fuel entering the combustion chamber in the primary zone with it's exit pointing straight at the turbine wheel. It seems to be fairly reliable now and I've not had any major dramas with it.. Cheers, Smithy. |
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Post by Richard OConnell on Dec 18, 2011 18:05:49 GMT -5
Chris, you wouldn't be making considerations on how to light "afterburners" on your new project would you?  |
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Post by turbochris on Dec 19, 2011 9:34:39 GMT -5
Richard, if I had my way. everyting I owned would have a built in fire show. Smithy, did you add a nozzle or use something existing? I've never had my gas generator apart. I remember you're using a timer built into the RC but are you using a pump, valve/ pressure tank? How big is the hot streak jet?
On this little bike they're called AnkleBurners, not AfterBurners......
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Post by Richard OConnell on Dec 19, 2011 12:50:02 GMT -5
Well, I suppose your legs aren't going to shave themselves...
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smithy
Member
Joined: August 2010
Posts: 31
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Post by smithy on Dec 19, 2011 16:46:02 GMT -5
Richard, if I had my way. everyting I owned would have a built in fire show. Smithy, did you add a nozzle or use something existing? I've never had my gas generator apart. I remember you're using a timer built into the RC but are you using a pump, valve/ pressure tank? How big is the hot streak jet? On this little bike they're called AnkleBurners, not AfterBurners...... Hey Chris, I added a nozzle to the combustion chamber, but I didn't go in through the outer case, I fitted a small 3mm festo fitting connected to a stainless tube (2.5mm) down through the diffuser in a similar fashion to the normal propane and fuel lines. The Wren will have a similar setup. I just removed one of the diffuser cover attaching screws and passed the stainless tube through there. I then tapped out the hole to take the festo male 5mm x 0.8mm thread. The stainless tube then passes down the outside of the combustion chamber until it reaches one of the small primary holes and I poke it in through there, pointing it at the turbine wheel ~midpoint of the blades. I've not had any dramas with burnt blades or NGV as yet. I originally had a fairly wide spray pattern but found it was only effective at low rpm, I now have a straight spray shot, much like a garden hose, this seems to carry the flame further down the exhaust and allows a reliable light-off pretty much every time. You'll need to fit a check valve in each line though as the CC and A/B pressure tends to force the fuel back through the pump when they're not in operation and forces the fuel back into the tank causing pump cavitation when you next activate it. I'm using the main A/B pump (actuated by a momentary switch on my radio) and run a "T" fitting to the hotstreak, I've not worried about using a timer since I had A/B flame-out issues some time back. I actually have two A/B pumps, one supplies the hot streak and normal spray ring, the other is used for a "supplementary" injection system for a nice big fire show at lower rpm's. I just run the two supplementary supply lines to the back of the A/B can about 1" from the exit, this gives a nice 3 meter flame for entertaining the kids. At higher rpm and at higher mass flow and speed the flame disappears up the exhaust and becomes a really nice thrust producing small blue flame. I get ~30-35% extra thrust depending on ambient conditions. John (Racket) has seen it running and commented on how well it was running, which was a nice thing to hear. If you need help with a hot-streak setup, let me know and we'll see what we can do for you..! I'd suggest you may need something a little different for your gas producer/free-turbine setup but the principle will be similar. It may even be appropriate to fit a small Jacobs Ladder setup in your exhaust with fuel injected just upstream of this. I believe you may have something similar in your Nimbus powered van??? Cheers, Smithy. |
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Post by turbochris on Dec 20, 2011 11:23:30 GMT -5
"supplementary" injection system..... you and Ernie would get along great. His fuel pump in the yellow pickup pulls over 100 amps at 24 volts........ while the turbine is idling.... full AB fuel flow... you get the picture.. Anyway, so you're just turning the pumps on and off to control fuel flow? My experience is solenoids react much faster but one great thing about a pump over a solenoid is when you cut the power, a solenoid can hang open and still give flow, a pump just stops. what's the ID on that 2.5 SS tube? I'm with you, a nice straight shot of fuel right into the turbine, keep it tight and it will streak right out the tailpipe. I'm using a hot streak on the nimbus, timer with 2 Compucar solenoids. I've never seen one of Ernies solenoids fail but it's best to have redundancy with the hot streak. The fuel to the spray bars is from an electric fuel pump that had the motor timing advanced and is run off 24 volts instead of 12 volts.
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smithy
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Joined: August 2010
Posts: 31
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Post by smithy on Dec 20, 2011 15:39:05 GMT -5
Hi Chris,
The ID of the little "hot-streak" is only ~0.80mm so nothing huge. I had to play around and experiment with pressures and flows to get it happening the way I like... but it works and works pretty well now.
Cheers,
Smithy.
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smithy
Member
Joined: August 2010
Posts: 31
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Post by smithy on Dec 20, 2011 15:58:13 GMT -5
Hi Guys,
Just another little update and to get back on topic, I've finished the "starter bendix" setup for the Jet Kart, I've made it pretty much exactly the same as the one used for my micro turbine starters. I figured if it worked for them, it should work for the 6041..!
I have it attached to a Castle 1717 (1580kv) brushless motor, this thing has some serious torque and will happily pull just shy of 0.5lb-ft @ 100amps with no dramas.
Cheers,
Smithy.
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Post by racket on Dec 21, 2011 19:24:20 GMT -5
Hi Smithy
I'm going to be very interested in how this setup performs
Did you just scaleup a "standard" bendix ??
Its going to be awesome when its finished :-)
Cheers
John
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smithy
Member
Joined: August 2010
Posts: 31
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Post by smithy on Dec 21, 2011 21:06:58 GMT -5
Hi Smithy I'm going to be very interested in how this setup performs Did you just scaleup a "standard" bendix ?? Its going to be awesome when its finished :-) Cheers John Hi John, I sent you a PM regarding the starter bendix, attached is a pic of the offending item!!??....and yes, it's just a scaled up version of a micro turbine unit.....I had to "hand make" it too....took me an eternity to get it right  Cheers, Smithy. Attachments:
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Post by racket on Dec 21, 2011 21:16:08 GMT -5
Hi Smithy
Thats nice :-)
Cheers
John
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Post by pitciblackscotland on Dec 21, 2011 22:10:58 GMT -5
Hi Smithy, I have a small starter Bendix and was thinking of scaling up for my T 30 turbojet project, i have a castle 2650KV brushless motor and yes they have some serious torque. I sent it to John to try on his 10/98 but wasn't powerful enough but it might do the job for the T 30. I got my fingers crossed for you as i hope it will work out, looks like you spent many hours on that thing very nice job  Cheers, Mark... |
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smithy
Member
Joined: August 2010
Posts: 31
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Post by smithy on Dec 22, 2011 2:11:16 GMT -5
Hi Smithy, I have a small starter Bendix and was thinking of scaling up for my T 30 turbojet project, i have a castle 2650KV brushless motor and yes they have some serious torque. I sent it to John to try on his 10/98 but wasn't powerful enough but it might do the job for the T 30. I got my fingers crossed for you as i hope it will work out, looks like you spent many hours on that thing very nice job Cheers, Mark... Hi Mark, Yes, John told me of his exploits with the Mamba Monster 2650kv motor and how it fried the controller..!  I'm afraid it would not have anywhere near enough torque for the 6041, as mentioned earlier I'm using a Castle 1717 (1580kv) motor and it definitely has some serious power behind it and I've got no reservations about using it on the 6041. If fact I did a "Mock-up" mounting of it this afternoon and gave it a good old fashion spin on the 6041, I'm uploading the video to Youtube as we speak, I'll give a link to it when I can. It works extremely well and will easily turn the 6041 up to well over 10,000rpm with over 70psi oil pressure using a 14.8v 4s 4000mah 45c Lipo battery. Cheers, Smithy. |
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Post by pitciblackscotland on Dec 22, 2011 3:21:39 GMT -5
Hi Smithy, Ok so the 1580kv has more torque than the 2650kv motor, but i think it will be enough power to get the T 30 up and runing as it's not as big as the GT60 turbo. I am looking forward to a successful start up - Cheers, Mark. |
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I'm afraid it would not have anywhere near enough torque for the 6041, as mentioned earlier I'm using a Castle 1717 (1580kv) motor and it definitely has some serious power behind it and I've got no reservations about using it on the 6041.