captainG Posted January 21, 2015 Posted January 21, 2015 (edited) Ok so I did a search on a lot of dif threads but couldn't really find an answer so here is my question. I have made quite a few rockets now with 0 catos....knock wood. so I think I'm ready to take the next step and start trying different payloads and lift capability with flour, smoke,then cut stars. So what's the advantage of having a delay as opposed to just drilling the bulkhead with a charge to fire before apex? And what circumstances would call for the use of each? Edited January 21, 2015 by captainG
alexpyro101 Posted January 21, 2015 Posted January 21, 2015 I think it's just to let the rocket fly as high as it can before exploding. I think if you were to just drill a hole there would still be some fuel left to burn off when the header. Imagine those little moon traveler rockets, they only burn for like half a second, but they keep traveling up for quite some time before exploding because of the delay comp. I don't think the effect will be quite as drastic as the larger rockets but I'm sure it will be noticeable. 1
nater Posted January 21, 2015 Posted January 21, 2015 A coreburner motorn with no delay would burn for about 0.5 - 0.7 seconds and then ignite the heading. Obviously you want a motor to coast a ways before displaying its heading. Last fall I made a whistle rocket with too little delay. The heading was old napthalene smoke stars broken with BP and whistle. The short delay blew through and I ended up with a salute about 10 ft off the ground. Impressive, but not what I had in mind. A delay allows the motor to reach the intended altitude. Personally, I like the drama when a rocket reaches apogee and just arcs over before the heading ignites. A delay can be the same fuel you use as thrust or it can be a different effect. A clay bulkhead may or may not be needed as well. 1
alexpyro101 Posted January 21, 2015 Posted January 21, 2015 you could always attach a ball shell at the top too with some time fuse or taped up visco for the delay.
captainG Posted January 21, 2015 Author Posted January 21, 2015 I guess I should have mentioned these are 3/4" core burners made of pounded 60/40 powder drilled about 3" into 4" of fuel. So I guess that brings me to a couple other questions. Does the core do better if it goes all the way to the top or is the way I'm doing it ok? Also when inserting fuse should it go all the way in the hole like i have been doing or is just in a little bit ok? Thanks cap
schroedinger Posted January 22, 2015 Posted January 22, 2015 60/40 Sugar /KNO3 or Charcoal/KNO3? On a 1 lb you can mostly go up to 5" core and 3/8 nozzle diameter.Give it about 2-3 seconds delay to reach hight.
FLMark Posted February 8, 2015 Posted February 8, 2015 I could be wrong, but with sugar fuel, it seems like if you're drilling 3" deep in to 4" worth of fuel, then you should already have an appropriate delay built in right there (the un-drilled fuel). 1
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