Pyrojack84 Posted February 23, 2015 Posted February 23, 2015 I was wondering how big of a rocket I would need for a 2.5 inch heading. Thanks!
mikeee Posted February 23, 2015 Posted February 23, 2015 Depends on the fuel you are using and motor type. An 8oz or 1lb motor should lift a 2-1/2" header, also depends on the weight of the header you are mounting on top of the motor. Fuels (R-Candy, BP, Strobe, Whistle, etc.) can vary widely on performance.
nater Posted February 23, 2015 Posted February 23, 2015 Whistle or BP? Cored or end burner? Ball or cylinder? A 3/4" BP coreburner will easily lift that, a 5/8" BP motor should as well. A 1/2" whistle should work, maybe even BP depending on the contents of the header and the strength of the motor.
Pyrojack84 Posted February 23, 2015 Author Posted February 23, 2015 Im going to use a bp core burning rocket and a ball shell heading.
nater Posted February 23, 2015 Posted February 23, 2015 A 5/8" (8oz) or 3/4" (1 Pound) motor should do the trick for you.
nater Posted February 23, 2015 Posted February 23, 2015 I bet a six pounder would do it too! I bet a 2.5" salute would sound like a firecracker if it were lifted on a 6 pounder.
dagabu Posted February 23, 2015 Posted February 23, 2015 I bet a 2.5" salute would sound like a firecracker if it were lifted on a 6 pounder. Yea but the echo is well worth it! 2
Pyrojack84 Posted February 23, 2015 Author Posted February 23, 2015 I bet a six pounder would do it too! nah it would hardly get off the ground 1
mkn Posted February 23, 2015 Posted February 23, 2015 also I like to test a motor with a sandbag header of equal weight and shape to see if it will lift properly because of all the variables mentioned above.It's much better to see a sandbag coming back down with the motor still hot, then a live header that you are about to see go where you did not want it to....... Matt
MarkU1967 Posted February 28, 2015 Posted February 28, 2015 I think it would suck having a sand filler dummy go where it wasn't intended to go too.
calebkessinger Posted February 28, 2015 Posted February 28, 2015 my 1/2 in core burner rocket tooling with decent bp nozzled or non will lift 2.5 in ball shells just fine... If you are worried about a tester shell , just use some dog food, or chicken feed put a little bag of bp with a passfire or fuse into the rocket. I do it all the time with just enough bp to break the shell apart and still make it usable again.. The best way to find out is Light Something!!!
MrB Posted February 28, 2015 Posted February 28, 2015 I think it would suck having a sand filler dummy go where it wasn't intended to go too.A sand filled dummy that ends up in the wrong place, or a live shell.... I know what i'd prefer. However, one shouldn't ever be "test firing" where it actually matters if/when the dummy returns. Ideally, live shoots shouldn't be in a area where it matters either. But in reality, live shoots tend to have spectators somewhere. So it makes a bit of a difference.B!
nater Posted March 1, 2015 Posted March 1, 2015 It is wise to build a small flash bag inside dummy header to break everything apart at apogee. A weighted header will turn the rocket into a lawn dart on the way down.
dagabu Posted March 3, 2015 Posted March 3, 2015 It is wise to build a small flash bag inside dummy header to break everything apart at apogee. A weighted header will turn the rocket into a lawn dart on the way down. Pet food or kitty litter and Nates 1g salute works fine for testing.
ddewees Posted March 3, 2015 Posted March 3, 2015 I think I spend more feeding my dogs than myself. That stuff ain't going to waste at my house.
wildcherryxoxo Posted March 3, 2015 Posted March 3, 2015 I would go with 3/4" - once you get into rockets you will be able to tweak and tune smaller motors to do the job, but 3/4" is a good size to start with IMO. Scratch dummy headers all together, fill the bitches with flash! 1
BurritoBandito Posted March 3, 2015 Posted March 3, 2015 ...Scratch dummy headers all together, fill the bitches with flash!Are you serious, or is this just your obligatory "press the hot button" post of the day? 1
wildcherryxoxo Posted March 3, 2015 Posted March 3, 2015 Are you serious, or is this just your obligatory "press the hot button" post of the day? im not trying to shake the mill on this one, im being serious, debris isnt fun. Yes ideally you arent testing in suburbia, but even still, id rather have a flash header. If you are super concerned about performance, get a load cell.
nater Posted March 3, 2015 Posted March 3, 2015 I am with wildcherry on this one too. I don't want a full rocket coming down without being broken apart. I generally use small salutes when testing motors which just slip on the OD of the motor tube. Once a motor is dialed in and you need to test a full weight header, just use a dummy shell with a flash bag or a normal salute on top. Using the binary method, one can do this with relative safety. A test stand also works to know the lifting ability for a motor, but I still like to see one fly with the desired heading too.
BurritoBandito Posted March 4, 2015 Posted March 4, 2015 im not trying to shake the mill on this one... dick.You have a valid rebuttal. The wording "fill the bitches with flash" threw me for a loop. I pictured some colossal 70:30 salute on a questionable motor. A small salute being used to break the rocket is a whole 'nother story.
chand Posted March 25, 2015 Posted March 25, 2015 My propellent is kno3 and sugar and my combustion chamber is of 3 cm diameter and nozzle of 2 to 3 mm will it substance pressure
dagabu Posted March 25, 2015 Posted March 25, 2015 My propellent is kno3 and sugar and my combustion chamber is of 3 cm diameter and nozzle of 2 to 3 mm will it substance pressure Chand, What is the inside diameter of your motor? If your spindle hole is 3 cm and your nozzle throat is 3 mm, you should be fine in a 12 mm ID rocket.
chand Posted March 25, 2015 Posted March 25, 2015 Chand, What is the inside diameter of your motor? If your spindle hole is 3 cm and your nozzle throat is 3 mm, you should be fine in a 12 mm ID rocket. Means you are saying that should of 12 mm
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