Post by rockooby on Jun 27, 2024 21:03:01 GMT -5
Hi everyone I made my rendition of the full size Bruce Simpson 55lb pulse jet. It incorporates the straight between two 90 degree bends instead of the called for 180 degree bend, as I was unable to find a premanufactured 180 bend within my range of size specifications and I didn't want to make one again. This full size pulsejet is showing more promise than my 35% pulsejet ever did. It is still leaky (by leaky I mean when I fill the PJ completely with water there are a few drips maybe 10 or 15 consistent dribble no jets of water coming out these are not water geyser leaks) but I was on the verge of running out of welding gas, so I decided to try it out with the leaks. I welded the same fitting from the 35% pulse jet (a drilled through 1/4 steel compression fitting with 1/4 inch tubing acting as the fuel rail) onto the new pulsejet and reused the fuel tubing from the 35% pulse jet as well. Just drilling more holes to get around 50 square mms (the holes were 10 2.7mm holes in addition to 8 1mm holes from the 35% PJ.) I was a bit hasty and left some pretty big burrs in the drill holes I'll fix those tomorrow. Sadly, I could not get it to run today as it would start pulsing then I would take the leaf-blower off the intake and the pulse would slowly fade away into silence. I attributed this to the leaks ruining my pressure waves, is this a good assumption?
Also this might be basic level pulsejet knowledge I'm missing but its worth asking. When I'm starting the pulse jet I light it off from the intake and then start to blow with the leaf-blower then just adding or taking away gas and air to get it to the proper air to fuel mixture(I watched a Colin Furze video on lighting a pulsejet with a blow lamp at least six times.) But with my 35% pulsejet I noticed if I turned on the gas and blew air into the inlet I could light the outlet of the PJ, then the pulsejet would make a deafening sound that sounded more like what I would expect a pulsejet to sound like. This led me to doubt the way I've been trying to start my pulsejet. I tried both methods with the large pulsejet and I couldn't get it to sustain either. I recorded examples of both procedures of starting the pulsejet. When I light it from the front the whole length of pipe gets near cherry red like a pulse jet should, though in the video I didn't get it to sustain very well as my bottle was chilled and low on gas from previous try's. When I light my pulsejet from the back I notice only the very end of the exhaust cone gets cherry red. I assume I'm just wasting lots of gas with little thrust to show for it as per it all being used to make the deafening sound outside the pulsejet where it does no good. Which is the right way to start it any suggestions?
I've also been working on a auto coil circuit with a ne555. I tried one circuit I found on Bruce Simpsons website but I couldn't get it to continuously spark as the ne555 didn't want to time with this setup (I'm not sure if it was the way I set it up or just the circuit configuration in general but I couldn't get the ne555 to time.) So now I'm trying just a bare bones ne555 astable timer circuit with ne555 hooked to a transistor base with collecter and emitter joining the coil ground wire in an attempt to ground out the coil like on my car a few times every second. This has not worked yet either. Though now the ne555 is actually timing. With this I've seen massive voltage jumps on the oscilloscope. I don't know exact voltage as it is a old oscilloscope and the screen cannot contain the whole graph on the largest frame setting. So I just compared a 12volt signal to the other signal that was truncated at the top and the coil is outputting at least 200 volts. Though that is relatively high its not that high for a coil and sparkplug setup. So now I want to try a larger 12 volt battery as the one I've been testing with is small and probably needs to be charged. If that doesn't work I'll see if its might be the components I'm using leading to the lack of voltage and lack of spark. I hope to be able to add a spark plug to my pulsejet soon.
Oh also learned when I you heat concrete like with a pulse jet lit from the outlet laying on it likes to explode. Very amusing after I caught my breath. I took a picture of the damage.
Thanks
Below is me lighting the PJ from the back
Below is me lighting my PJ from the front
Below is the Colin Furze video I used for PJ starting reference
youtu.be/raT_8B7kP38
Also this might be basic level pulsejet knowledge I'm missing but its worth asking. When I'm starting the pulse jet I light it off from the intake and then start to blow with the leaf-blower then just adding or taking away gas and air to get it to the proper air to fuel mixture(I watched a Colin Furze video on lighting a pulsejet with a blow lamp at least six times.) But with my 35% pulsejet I noticed if I turned on the gas and blew air into the inlet I could light the outlet of the PJ, then the pulsejet would make a deafening sound that sounded more like what I would expect a pulsejet to sound like. This led me to doubt the way I've been trying to start my pulsejet. I tried both methods with the large pulsejet and I couldn't get it to sustain either. I recorded examples of both procedures of starting the pulsejet. When I light it from the front the whole length of pipe gets near cherry red like a pulse jet should, though in the video I didn't get it to sustain very well as my bottle was chilled and low on gas from previous try's. When I light my pulsejet from the back I notice only the very end of the exhaust cone gets cherry red. I assume I'm just wasting lots of gas with little thrust to show for it as per it all being used to make the deafening sound outside the pulsejet where it does no good. Which is the right way to start it any suggestions?
I've also been working on a auto coil circuit with a ne555. I tried one circuit I found on Bruce Simpsons website but I couldn't get it to continuously spark as the ne555 didn't want to time with this setup (I'm not sure if it was the way I set it up or just the circuit configuration in general but I couldn't get the ne555 to time.) So now I'm trying just a bare bones ne555 astable timer circuit with ne555 hooked to a transistor base with collecter and emitter joining the coil ground wire in an attempt to ground out the coil like on my car a few times every second. This has not worked yet either. Though now the ne555 is actually timing. With this I've seen massive voltage jumps on the oscilloscope. I don't know exact voltage as it is a old oscilloscope and the screen cannot contain the whole graph on the largest frame setting. So I just compared a 12volt signal to the other signal that was truncated at the top and the coil is outputting at least 200 volts. Though that is relatively high its not that high for a coil and sparkplug setup. So now I want to try a larger 12 volt battery as the one I've been testing with is small and probably needs to be charged. If that doesn't work I'll see if its might be the components I'm using leading to the lack of voltage and lack of spark. I hope to be able to add a spark plug to my pulsejet soon.
Oh also learned when I you heat concrete like with a pulse jet lit from the outlet laying on it likes to explode. Very amusing after I caught my breath. I took a picture of the damage.
Thanks
Below is me lighting the PJ from the back
Below is me lighting my PJ from the front
Below is the Colin Furze video I used for PJ starting reference
youtu.be/raT_8B7kP38
