usapyro Posted November 4, 2012 Share Posted November 4, 2012 (edited) Anyone find the specific impulse for whistle mix anywhere? NA Sally and NA Benz are what I am looking for. I have not managed to find the specific impulse information for any type of whistle mix... Here is what I do know... After an hour of searching around on google this is all I managed to find... No whistle! BP = 80, Sugar Fuel = 130, APCP = Around 300, NG/NC = 235(250 alumnized), and ANCP = 180. Edit: Wrong forum, please move to rocketry! Edited November 4, 2012 by usapyro Link to comment Share on other sites More sharing options...
AirCowPeacock Posted November 4, 2012 Share Posted November 4, 2012 Just putting it out there, based on performance compaired to those other fuels, I would guess Whistles ISP in those units is greater than 130 (Sugar Fuel) and below 180 (ANCP)... this isnt very helpful of course. There is a way to calculate the ideal--maybe you could hust do that. Link to comment Share on other sites More sharing options...
gregkdc1 Posted November 4, 2012 Share Posted November 4, 2012 (edited) I think the numbers you have posted for the propellants are with nozzles and in a high pressure motor. Also the number for APCP looks like it is in a vacuum, normally at sea level in a small motor APCP will get you an isp of around 180-200. Without the nozzle it may be hard to determine the ISP of whistle mix but given the fact that it is a low pressure motor without a nozzle and the maximum theoretical isp at 1000 psi is usually around 180 I wouldn't be surprised if it is similar to sugar or black powder. If you had a test stand you could calculate it. Edited November 4, 2012 by gregkdc1 Link to comment Share on other sites More sharing options...
Algenco Posted November 4, 2012 Share Posted November 4, 2012 everything can be found here Link to comment Share on other sites More sharing options...
AirCowPeacock Posted November 4, 2012 Share Posted November 4, 2012 Well thats mesure ISP, which doesnt show the ideal, inefficency is inevitable, you could high ISP then mesure there. But check out the WM catalyst tests. That should give you a good idea. Link to comment Share on other sites More sharing options...
usapyro Posted November 4, 2012 Author Share Posted November 4, 2012 I looked through there. Great website... But he doesn't list ISP's anywhere? everything can be found here Link to comment Share on other sites More sharing options...
AirCowPeacock Posted November 4, 2012 Share Posted November 4, 2012 http://creagan.net/fireworks/rockets/whistletests.html The product of the average thrust and the burn time is the total impulse. Devide the total impulse by the fuel weight and you have mesured specific impulse. Link to comment Share on other sites More sharing options...
nater Posted November 4, 2012 Share Posted November 4, 2012 http://www.nakka-rocketry.net/impcalc.html You will need a test stand too, let us know what you find out when you press and test some motors. https://lh4.googleusercontent.com/-fb7utnxeA_g/UHi0-caWqCI/AAAAAAAABE4/MMhgwn4XswY/s1024/Nate%252B.750%252BSuper%252BWhistle.jpg. there is one of my thrust curves, but one would have to estimate the mass of the fuel burned in the core. Link to comment Share on other sites More sharing options...
usapyro Posted November 4, 2012 Author Share Posted November 4, 2012 (edited) So... For brown iron oxide... Core thrust time 0.87sec x 1000g average thrust = 870g thrust/second. 870/25g of fuel = 34.8... Whistle mix has an ISP of 35??? That can't be right... If you calculate with core average thrust x time... It calculates out to a ISP of 170. Not sure I'm supposed to be using core thrust duration or time in the calculation. Edited November 4, 2012 by usapyro Link to comment Share on other sites More sharing options...
AirCowPeacock Posted November 4, 2012 Share Posted November 4, 2012 Yeah, that cant be right.. hmm... I wonder who, and where the mistake was made. The integral of thrust would be the average thrust multiplied by time right? Link to comment Share on other sites More sharing options...
usapyro Posted November 4, 2012 Author Share Posted November 4, 2012 I think you need to measure the amount of gas output and temperature of burn versus the amount burned or something to get ISP... Link to comment Share on other sites More sharing options...
nater Posted November 4, 2012 Share Posted November 4, 2012 You need to meausre the exit velocity of the exhausted basses vs the amount burned over time, but according to Nakka's site I linked above yoh can figure it out from thrust curves as well. That is probably why you found data for rcandy, bp and apcp since the HPR crowd uses those fuels and needs more exact details of the motors than pyros. I am not aware of any whistle motors for HPR. I have often been curious how close our whistle fuels get to APCP, I think with some the lines between them get blurred. Link to comment Share on other sites More sharing options...
usapyro Posted November 4, 2012 Author Share Posted November 4, 2012 (edited) I found some questionable information from someone talking about the "predicted" specific impulse of whistle mix being 166. Also, this explains why perchlorate is not used in rocket fuel..."Oxidizers used in composite propellants : Potassium perchlorate (KClO4). Potassium pechlorate was one of the first used oxidizers. One of it's draw- backs is the product of decomposition ( potasium chloride ) is not a gas at regular temperatures and does not contribute as a working gas. The KCl appears as a dense smoke in the rockets exhaust. Burning rates of propellants made with KClO4 are usually high at 0.8 - 0.9 in/sec at 1000 PSI. Densities of fuels made with KClO4 also tend to high at 1.8 - 2.0 gm/cc. Specific impulses are usually below 200 lb-sec/lb. Potassium perchlorate is hardly ever used im modern propellants." Edited November 4, 2012 by usapyro Link to comment Share on other sites More sharing options...
AirCowPeacock Posted November 4, 2012 Share Posted November 4, 2012 pound-sec per pound. So thats force-time per propellant mass. So the integral of force, which should be average force multiplied by time, over propellant mass. I know, you used grams as your force unit, but grams are not a unit of force. Try newtons and kilos. Or poundfeet (force) and pounds (mass.) Link to comment Share on other sites More sharing options...
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