Aces High Bulletin Board
General Forums => The O' Club => Topic started by: Sol75 on March 23, 2009, 10:47:26 AM
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Hey guys,
I have an R/C Byron F-16, with a Jetcat P-80 turbine. I have drawn out plans for a functional afterburner to be used on it. (mainly for scale purposes rather than true performance boost, but that could be fun too lol). My question is, do any of you know of, or can, build this contraption for me? I did all the drawings in AutoCad. I know nothing about metalworking, so, I appeal to those of you who are skilled in such things to get in touch with me! (and yes, this IS an afterburner, not a lighting setup that mimics one). Should put a nice cone of flame out the rear of the jet, and add some power as well.
Who knows,
If it is succesful, there might be a future in selling these things to other modelers.... If that happens, I would be glad to offer whoever made it first right of refusal to make more for other people.
Sol
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Did you also plan for the added fresh airflow into the exhaust stream when afterburner goes online?
How much pressure is the pump delivering to the afterburner?
What fuel do you plan on using for the afterburner?
Are you adding the exhaust port/cone for the afterburner to the exterior, or do you plan on fitting it internally to the tail?
If I had the bandwidth, it would be a fun project.
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SHawk owns a machine shop, you may want to contact him and see if he is interested.
TD
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I see an explosion coming.
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Just get a bypass air supply and throw a fuel line back there. Make sure u record ur first flight PLS :devil
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Oh man that looks pretty tough. I wouldn't know but if you go to RCU, you might get an answer.
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Skuzzy:
Did you also plan for the added fresh airflow into the exhaust stream when afterburner goes online?
Yes, I did, I drew plans for a new tailcone that will allow scoops to open ahead of the spray nozzles for the afterburner, with ignition of the afterburner, providing a source of fresh air. Scale? no, but at speed and altitude they should be quite unobtrusive. functional? not really known, but should be.
How much pressure is the pump delivering to the afterburner?
Unknown yet. This will have to be done via trial and error, if done solely by myself. I am a network engineer, not aerospace engineer :) this is a hobby! But, this should be reasonably simple to try different values until I obtain the ideal situation.
What fuel do you plan on using for the afterburner?
The same thing the turbine runs on, Jet A, or Kerosene with oil additives.
Are you adding the exhaust port/cone for the afterburner to the exterior, or do you plan on fitting it internally to the tail?
I am intending to add it to the interior of the tail. I also have a.. much less detailed and MUCH less expensive aircraft which i got from a friend when i first got into turbines.. basically a traditional balsa built up airframe, but designed as a
"turbine trainer". Will likely use that as my testbed jsut in case something goes wrong. Don't want to destroy the F-16, put WAY too much time into it.
If anyone has ideas on anyting for this, I would be GLAD to hear from you.
Sol
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I have a CNC rig, drill press and CNC lathe. Just wish I had the bandwidth for this.
Putting the cone internally is going to be a challenge, due to heat. Also, you need to cone to have a slight bell at the intake edge (from the exhaust of the turbine) to prevent shock wave feedback up the stream. I assume the profile of the cone's internal shape is parabolic?
How long is the cone from the onset of fuel introduction? I can run some calcs on the parabolic shape based on kerosene fuel.
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I see an explosion coming.
Now thats just funny :rofl
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Would definitely get Shawk involved. I've been to his shop and he can program the machines to build it up for ya in 3d if you got the CAD drawings and dimensions worked out.
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Hehe..wow you guys dont mess around. If it were me Id duct tape a torch to her and let her rip!
Arent afterburners super intricate? I cant imagine trying to machine the parts involved.
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Sounds like a -Hey watch this -- moment in the making
They always have interesting outcomes
:)
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Which is precisely why im not just stickin this thing on a plane and letting it rip. Why im posting here, seeking the advice of a freind of mine who is an aeronautic engineer that works for General Electric, etc etc. As for your question abt that cone Skuzzy, as son as I hear back from said friend, I will let you know the specifics on it :)
Sol
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sol, I'll take a look at it, but I likely think you will have to have a tail cone extruded or pressed. I might be able to find some things around here to use, but I am not sure. Send me a PM and you can send me your plans and we can go from there if you want.
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Links i found for RC engines with AB.
http://translate.google.com/translate?sourceid=navclient&hl=en&u=http%3a%2f%2fwww.skypipe.de%2findex.php%3fsite%3dturbinen
http://www.airtoi.com/special/spec2.htm
thread
http://www.rcgroups.com/forums/showthread.php?t=413487
http://www.moddedmustangs.com/forums/clubhouse/108903-r-c-model-f-16-w-afterburner.html with VIDEOS!
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Have you figured out the specific materials and run calculations yet? Also are you looking at formed and fabricated or machined.
If you have autocad drawings I'd like to take a look at them if you don't mind. Sure sounds interesting. My email is p38lightning@gmail.com.
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I can see it today.....
(http://ah8thairforce.org/Sols.gif)
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I will be sending the drawings to those of you interested. I may have put the cart before the horse on some things though. I need some help, before i can have anything "built". I will be formulating a list of items I need to know before beginning fabrication or anything, and post it here. Maybe with everyones help I can get this thing up and running, SAFELY.
Sol
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When you started the thread, I went over in my mind what goes into a modern afterburning engine to make it work reasonably seamlessly for the pilot... Variable bypass for cooling and flow control, variable nozzle area to control pressure and EGT, flame holder and injector design, ignitors, light-off detectors that automatically cut burner fuel supply if the thing doesn't light off right away or if the burner blows out, etc etc... I figure you ought to be able to make it function with just a tube, flame holder, injectors, and igniters, but it won't run right and you'll have to be very concerned with temps and what it does to the engine. To make a simple model turbine burner, you'll probably end up doing a LOT of static ground testing (with and without forced airflow to simulate flight conditions) just to keep the thing from blowing up or melting inflight. Buying one that's already been tweaked is probably a better idea.
Ironically, the more complex you make the system, the less testing you'll need because you'd be able to adjust the various parts on the fly. Have bypass airflow automatically increase when the ignitors are running. Have fuel flow tied to igniter operation. Have igniters run on a timing system where they only operate for 2 or 3 seconds if a light-off is not detected, and cut it all off at 20-30 seconds if there is a good light-off. Use at least a two-step variable nozzle, closed down for normal operation and opened up for burner operation. Or tie nozzle area to EGT. Point being that a simple design with very few adjustments will be reliable but will take a hell of a lot of manual testing and tweaking to get to run right, while a very complex system could work pretty well with little operator input.
Again, I'd probably just buy one that someone else had already tested. Reliable full-scale afterburners took decades to perfect and only became truly reliable with the advent of full-authority digital engine control units. Even the F-15Cs in use at Tyndall AFB for training have a pretty high burner blow-out rate with the older engine control units, while an F-15E can do a tailslide with the pilot running the throttle from idle to burner and back, without the engine quitting. It's far more complex but much more reliable.
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just be careful with air intake and heat iv seen, both in real life and online were somebody at the field has something too close to the engine, (like a receiver covered in foam, only to find out the foam got fuel on it somehow) or when you may have goten a foreign object in the intake (like a pebble or a screw), and there engine in flight or taxying spews sparks or catches ablaze and damn that stuff is more flammable than it seems.
i have a question though,
how does afterburn work, all i know is that it make it go faster..
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Eagl,
Thanks for the input, I have been doing Turbine RC for about 4 years now, however, I am YET to see a functional afterburner, until the recent post in this thread. My thought was to create one of the 1st. Perhaps it is more complex for me to attempt, but, I would still like to make the attempt, IF it can be done safely. Ground testing is fine for me... and as for FADEC, our RC turbines already run on FADEC believe it or not. I would jsut need to find a way to adapt it for AB usage (if possible). Not sure how, perhaps I can see if the manufacturer of my turbine might be of aid.
I've always been fascinated by advancing the hobby/sport i love, I just completed a prototype testbed for a full VTOL and conventional transitionable V22 osprey. the testbed is UGLY as heck, but it works! Next is to build a scale model and put the system in that.
Afterburner is something I want to pursue after that is completed.... i did the plans for the tubes and such, but that swhy I brought the idea here... I dont know a lot aside from the physical layout of the AB... thus why I am soliciting input!
Sol
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Well then, if you want it to be different than that other one, give it a variable exhaust nozzle so you can run it for more than 20 sec :)
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Mach 1 RC plane, sounds like fun. :rofl
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Mach 1 RC plane, sounds like fun. :rofl
lol I can se it now, Sol gets the first FAA fine for making a sonic BOOM with a RC plane.
Wonder if the AF has trie putting AB's on any of their UCAV test models? If ya think about it all they are is bigger and WAY more expensive RC toys, just more complex and can make things go boom
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http://www.moddedmustangs.com/forums/clubhouse/108903-r-c-model-f-16-w-afterburner.html with VIDEOS!
That f-16 isn't a real afterburner. It has led lights and water injection to simulate the look of an afterburner (and does it quite well), but its not a real flame.
Cool stuff, though. Those turbines are impressive.
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Wonder if the AF has trie putting AB's on any of their UCAV test models? If ya think about it all they are is bigger and WAY more expensive RC toys, just more complex and can make things go boom
I think the general concensus on UCAVs at this point is to rely on low observability, not speed. So the engines have engines and exhaust ducting that reduces radar and thermal signature at the expense of power and efficiency. In other words, no AB on most (maybe all) UCAVs so far.
Look at the back end of the F-22 and compare it to the F-35... The JSF gives up a LOT of rear-aspect stealth and IR signature in the name of lower costs.
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Jesus please film this stuff ! I bought a couple 35 dollar toy EPP P-38's got rid of stock 6 Volt 150 MaH nimhs . Replaced them with 7.4 720 Mah Lipos . Me and the 7 year old boy fly the crap out of these things every chance we get . I am brand new to this hobby . I just picked up a Park Zone RTF F4u Park flyer . It will stay in its box until the weather straightens up here in Oregon . Still need to pick out a trainer to destroy first as it looks like I will be doing this on my own . No local RC clubs that are active . Except for cars . Spend that kind of money on a toy what don't fly . I will be patiently waiting results on this , I will live vicariously thru all you guys care to share . My little story is to show my enginering skills level hence the need for films and photos <G>