Snailman

Snailman replied to a topic

Help checking missile acceleration calculations.

I would like to ask some people to please check my math for me with regard to SF2 missile acceleration.   First, I recommend opening the links below as tabs in a separate browser window, plus your Windows calculator in scientific mode with the unit conversion panel open.   Calculating rocket acceleration<-----Formula Source.   Convert Meters Per Second Squared to Standard Gravity   Convert Standard Gravity to Meters Per Second Squared   Convert Pounds-force to Newtons   Velocity, Acceleration and Time Calculator   Uniform motion (travel distance) Calculator   WesternElectricNikeHerculesBrown.pdf<-----The bulk of the missile data was drawn from this document.   Missile Data <-----This was used to fill in some blanks.      Now, here is the issue. I am calculating the booster and sustainer acceleration g-force for two missiles.   ||-----Formulas-----||   Weight (in kg) = Mass (in kg) x 9.81   Resultant Force (newtons, N) = Thrust (in N) – Weight (in kg)   Acceleration (m/s2) = Resultant Force (newtons, N) ÷ Mass (kilograms, kg)   //-----MIM-3 Data-----\\   The MIM-3 missile has a combined missile-booster weight of 2499.3 lbs (1133.663410341 kg). The missile’s weight is 1193.3 lbs (541.271775121 kg). The booster’s weight is 1306 lbs (592.39163522 kg).   The booster produces 59,000 lbs of thrust (262445.0753 N) for 3.5 seconds. The sustainer produces 2600 lbs of thrust (11565.3762 N) for 20.8 seconds.   //-----MIM-3 Calculations-----\\   Missile With Booster   11121.23805544521 kg = 1133.663410341 kg x 9.81   251323.83724455479 N = 262445.0753 N– 11121.23805544521 kg   221.69176049261208816117588018214 m/s2 = 251323.83724455479 N ÷ 1133.663410341 kg   22.606268 g = 221.69176049261208816117588018214 m/s2   Missile With Sustainer   5309.87611393701 kg = 541.271775121 kg x 9.81   6255.50008606299 N = 11565.3762 N – 5309.87611393701 kg   11.557040979394478940811698611408 m/s2 = 6255.50008606299 N ÷ 541.271775121 kg   1.178490g = 11.557040979394478940811698611408 m/s2   For Data File...   BoosterDuration=3.500000 BoosterAccel=22.606268   SustainerDuration=20.800000 SustainerAccel=1.178490   \\-----MIM-14 Data-----//   The second missile has a combined missile-booster weight of 10,550 lbs (4785.3995035 kg). The missile’s weight is 5,250 lbs (2381.3599425 kg). The booster’s weight is 5,300 lbs (2404.039561 kg).   The booster produces 173,600 lbs of thrust (772211.272409 N) for 3.4 seconds. The sustainer produces 13,750 lbs of thrust (61163.04721 N) for 29 seconds.   \\-----MIM-14 Calculations-----//   Missile With Booster   46944.769129335 kg = 4785.3995035 kg x 9.81   725266.503279665 N = 772211.272409 N – 46944.769129335 kg   151.55819336488235166633669125594 m/s2 = 725266.503279665 N ÷ 4785.3995035 kg   15.454635g = 151.55819336488235166633669125594 m/s2   Missile With Sustainer   23361.141035925 kg = 2381.3599425 kg x 9.81   37801.906174075 N = 61163.04721 N – 23361.141035925 kg   15.874083333403933748247300082398 m/s2 = 37801.906174075 N ÷ 2381.3599425 kg   1.618706g = 15.874083333403933748247300082398 m/s2   For Data File...   BoosterDuration=3.400000 BoosterAccel=15.454635   SustainerDuration=29.000000 SustainerAccel=1.618706
You are lucky if you have data!  I did this for 50+ missiles for the RSSW pack...  In many cases it's a pain in the big A, even with available RL data - but what to do. With this system we have and tools it is a happy result if we produced something near similar.   What I did, was entering real life values into the missile range calculator proggy, then thought it over, which values must stay, which can be altered. My goal was end-user performance, with priority 1. Correct range (including passive flight,) with correct lifetime (self-destruct) 2. Correct engine operating time 3. Correct speed - if possible - it is hard to test because missile range  calculator has only one height setting (IAS/TAS) so you have to check at low alt (0.95) medium (0.8616) and probably high (0.6 or 0.40) - then test fire against actual targets in-game and watch the speed value in debug mode +custom weapon view 5. Correct to-hit chance - another story of radar/jammer/missile issues 6. Altitude range, it has to be set in the attached SAM_Radar class network object (MinRadAlt + MaxRadarAlt), in mind with intermediate zones I mentioned 7. Misc features like maneuverability/guidance etc etc - have to consider guidance types here - as with Rear60 IRMs Beam-Rider (tail chasing) guidance routine is also useless.     I changed all SA-2 to SemiAuto - which is a bit strong but there is no such guidance which would  be in-between the two (command guidance with lead-computing)   Before   After     Use the cutoff speed to fix the operating time.  In case the missile system can guide a single missile only, it's important to optimize missile lifetime. The stock SA-2 after a miss, cannot fire a second missile for an entire minute until the previous one ends it's run on ballistic.