fat head Posted December 2, 2008 Share Posted December 2, 2008 Hi, a friend is looking advise on how to ignite a spark via a spark plug on a pulse jet he is working on. He is looking for something that can be attached to the plug then removed when the jet starts to fire up. It needs to cause a series of sparks to ignite the petrol vapour in the chamber. 12 v will be the power source i think! Quote Link to comment Share on other sites More sharing options...
simon barr Posted December 2, 2008 Share Posted December 2, 2008 Be careful, FH. As I understand it, pulse jets are illegal in the UK....I may be wrong here, and I'm sure someone will put me right if I am...But.... Quote Link to comment Share on other sites More sharing options...
flytilbroke Posted December 2, 2008 Share Posted December 2, 2008 Nope, not illegal Simon. Merely not allowed most areas. FH. Given no-one else has the answer for making your sparks I may be able to get the details for you. I know that it was found not to be a good idea to fit a spark-plug to the Pulsejet unit, but to use an external probe with the plug at one end and the control unit at a right angle at the exhaust end. Welders gloves were the order of the day for the guy inserting the probe Quote Link to comment Share on other sites More sharing options...
simon barr Posted December 2, 2008 Share Posted December 2, 2008 There you go, I was wrong... Quote Link to comment Share on other sites More sharing options...
Bert Posted December 2, 2008 Share Posted December 2, 2008 FH If it's any help, instead of a spark plug some people used to simply heat up the tailpipe with a blowtorch, once you get a bang the cycle starts and your'e away.And no, theyr'e not illegal if they are under control, just antisocial, I believe they are illegal to use free-flight.Bert Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted December 2, 2008 Share Posted December 2, 2008 Bert wrote (see)FH If it's any help, instead of a spark plug some people used to simply heat up the tailpipe with a blowtorch, once you get a bang the cycle starts and your'e away.And no, theyr'e not illegal if they are under control, just antisocial, I believe they are illegal to use free-flight.BertAs seen in use at the NATS this year....and boy they are still as noisy and scary as I remebered them to be! Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted December 3, 2008 Share Posted December 3, 2008 HiThe conventional way to fire a spark plug on a pulse jet is to use a "trembler" type coil (as used on the Ford Model T!). This has a moving armature switch (a bit like an electric buzzer) that switches the coil on and off rapidly giving an almost continuous stream of sparks, or you could move into the 21st century and use an automatic piezo system like those used on CH heating boilers, they spark about twice a second. Now whether the spark plug will actually light the fuel/air mixture in your pulse jet is quite another matter! Quote Link to comment Share on other sites More sharing options...
fat head Posted December 3, 2008 Author Share Posted December 3, 2008 Great, will pass this info on to my friend. heating the tail pipe sounds a good idea! i think it's a reid valve type jet. He will be at something yet! the turbines must be boring him! will let you know how it goes. thanks for the replys!... Quote Link to comment Share on other sites More sharing options...
Bert Posted December 3, 2008 Share Posted December 3, 2008 Timbo - forum moderator wrote (see)As seen in use at the NATS this year....and boy they are still as noisy and scary as I remebered them to be!You're right about that Timbo, I was about 13 when I saw my first pulse jet (at Tangmere I think) and I can still remember the panic that ensued all around me when the thing started up! Gosh - I was scared witless Quote Link to comment Share on other sites More sharing options...
Former Member Posted December 7, 2008 Share Posted December 7, 2008 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted December 8, 2008 Share Posted December 8, 2008 Also note a pulse jet is just that, it pulses! Not the buzz of an IC engine but full thrust on & off - several times a second! If you are going to fly it make sure everything on the model is fixed firmly.On a historical note the Americans spent some time just after the war trying to improve the V1, the worlds first cruise missile, code name "Loon" but found that the severe vibration made it difficult to make anything, including the pulse jet itself, last much longer than about 20 minutes. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted December 9, 2008 Share Posted December 9, 2008 This ferocious looking beast belonged to a friend of my dads. Beautiful made, he had an engineering business and could weld very thin stainless (rare in the 50's). I doesn't look like it has been run very much. My dad built a smaller one in mild steel - but that never worked properly - pulse jets are tricky things! Quote Link to comment Share on other sites More sharing options...
Ultymate Posted December 9, 2008 Share Posted December 9, 2008 A sure fired copper bottomed guaranteed way to lose your flying site is to fire up one of these puppies, sado masochistic tendencies are a definite advantage if your going down that road Quote Link to comment Share on other sites More sharing options...
fat head Posted December 9, 2008 Author Share Posted December 9, 2008 Simon your photo of a pulse jet is very like the one my friend has! your right about the noise!!! i was at a show in Scotland a few years ago and they had a twin pulse jet in the air a few times. It would be hard to let on to the wife you havn't been in the shed firing up one of these!!! But they are fun to watch.. I hope he takes on the advice you guys have posted. Colin. Quote Link to comment Share on other sites More sharing options...
Former Member Posted December 10, 2008 Share Posted December 10, 2008 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Matt Brewster Posted December 11, 2008 Share Posted December 11, 2008 Hi A friend of mine built one of those and used an old strimmer engine .He removed the spark plug from the strimmer so as to let it turnover freely and attached a cordless drill to the crank then attached the plug lead to jet and earth jet and engine together. apparently work's great. hope this is of help Quote Link to comment Share on other sites More sharing options...
fat head Posted December 12, 2008 Author Share Posted December 12, 2008 Matt, i found an old strimmer engine i had in the shed and give it to him ! i have printed your advice and told him to give it a try. I think this will work!! thanks for your advice. I have had some great advice by everyone who has posted a reply... Colin. Quote Link to comment Share on other sites More sharing options...
Matt Brewster Posted December 12, 2008 Share Posted December 12, 2008 Glad to help. Just one thing ,he said it made his ears painful so it might be a good idea to use ear fenders. Good luck and have fun.Matt Quote Link to comment Share on other sites More sharing options...
Doug Ireland Posted December 14, 2008 Share Posted December 14, 2008 My dad had one as a kid. It had a fuel tank that you had to pressurise with a bike pump, heat the pipe with a blowlamp, turn on the fuel and off it would go!He told me he got into all sorts of trouble one time when he tied the jet to his bike and went thundering down the High Street in Newport on the IOW, burning out the brake blocks in the process. Just after the war this wasn't one of his better ideas!And speaking of V1's (Eric), I had a photo of my old man as a 10 year old sitting astride a V1 that had come down in a field close to the family farm and didn't go off. Quote Link to comment Share on other sites More sharing options...
Former Member Posted December 14, 2008 Share Posted December 14, 2008 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
fat head Posted December 22, 2008 Author Share Posted December 22, 2008 Doug I had LOL picturing your dad sitting on the V1.. at what point did he decide that this thing won't go off???? LOL. Kids have no fear!! I remember watching a couple of kids hitting a 120mm mortar round in the middle east with a iron bar!!! I Did'nt hang around to long to find out if it was a dud. Quote Link to comment Share on other sites More sharing options...
dave windymiller Posted February 8, 2009 Share Posted February 8, 2009 My brauner pulsejet could be started using a blowlamp at the exhaust (not on it, that took too long). During a start a few puffs of air resulted in fuel at the exhaust which burnt like a lazy candle. As the fuel runs out, the flame would suddenly run back into the pipe with a wwwwump. If you timed it right, the next puff of air set it off. I also used a spark plug from an old petrol model engine. I drove it with an electronic ignition kit from a car shop (less popular these days) and it was driven by a 555timer set to 350hz. I used to push the button to set the sparks going but got lazy and put the 12v battery on the button. This was fine until you reached for the plug clip (forgetting to remove the battery off the button!!!). Its polished up as an ornament now that ive built a turbine Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted February 8, 2009 Share Posted February 8, 2009 just found this thread re-pulse jet's---read an article a few years ago about them--allthough not illegal--the article stated that if you used a one you would probably end up having model aircraft flying banned within a 5mile radius of where you were ken anderson. Quote Link to comment Share on other sites More sharing options...
flytilbroke Posted February 8, 2009 Share Posted February 8, 2009 Tell you what guys, make it a long weekend or holiday and come to the Machrihanish Fun Fly with your Pulse Jets. We can take anything legal so any other models large or small are also welcome. With luck we will have a nice delta fitted with three of them, there. Last year our Pulse jet jockey was stuck abroad so did not make it. Hopefully this year we will see him. Must register first though as the Airfield is still M.O.D. Quote Link to comment Share on other sites More sharing options...
Gemma Jane Posted February 8, 2009 Share Posted February 8, 2009 Just to be technically annoying Eric, the V1 was a ram jet not a pulse jet. I saw a twin pulse jet model displayed at North Weald many moon ago (this was like way back when the first commercial model turbines were being displayed to the public). That was totally awesome, but I still remember the terrible sound, I really admired the guy at the controls for the shear spectacle of the thing. Quote Link to comment Share on other sites More sharing options...
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