How to Use RocketCalc App - A rocket altitude and velocity calculator

To use RocketCalc, start by downloading the Android app to your Android smartphone.

Link to RocketCalc for Android smartphones

RocketCalc is a calculator to determine the altitude and velocity a model rocket is likely to achieve. To configure the parameters of your rocket, go to the Parameters menu item at the top of the main screen, or under the button in the upper right corner, and enter into RocketCalc the parameters of your model rocket and rocket engine. There are more details on what reasonable rocket engine parameters would be later on this page.

Model Rocket Calculator

RocketCalc will then display the likely flight profile. You can tap on the RocketCalc flight profile screen to find the altitude and velocity at any particular time during the rockets flight.

Model Rocket Calculator

If you want to know the specific maximum velocity, maximum altitude, or coast time go to the Results menu item at the top of the main screen, or under the button in the upper right corner.

Model Rocket Calculator

The paid version of RocketCalc, 'RocetCalc (No Ads)', allows you to save, and later open, up to four rocket parameter files. To save a rocket parameters go to File Save As under the button in the upper right corner, and select the file slot, one through four, that you want to save the parameters as. Once you save the file, if you make further changes to the parameters, you only need to select File Save to update the file, unless you want to change the file slot you're using. To open any file that you've saved at a later time, go to File Open under the button in the upper right corner, and select the file slot, one through four, that you want to open the parameters from.

Estes Engine Chart

The default parameter values preseted for RocketCalc are for a B6 rocket engine.

Students and teachers can use RocketCalc to calculate the likely flight profile of their own model rockets. They will need to enter some information about their rocket such as total mass and cross sectional area, and can come up with estimates for the parameters of the rocket engine based on the engine coding. To estimate the parameters of the rocket engine based on the engine coding you could try to derive it from the documented meaning of the coding such as:
     A8-#
     'A' indicates total Newton-Seconds of the engine to be between 1.26 and 2.50 Ns
     '8' should indicates average Newtons of 8 N
The problem is, this doesn't include the fuel mass. Alternately you can use an engine chart to come up with most of these parameters. For example, from the chart on the right, an A8-# engine would have:
     Average Force: 2.5 N s / 0.5 s = 5 N
     Max Force: (set same as Average Force)
     Total Duration: 0.5 s
     Max Duration: (set same as Total Duration)
     Fuel Mass: .00312 kg
These parameters would be reasonable; however, this still doesn't include the time of max thrust nor the total time of thrust. It also doesn't indicate actual measured values of engines. Instead of this, using static test data such as http://www.nar.org/SandT/pdf/Estes/A8.pdf would be better.

From NAR.org data, reasonable parameters to enter into RocketCalc for an A8 engine would be:
     Average Force: 3.18 N
     Max Force: 4.0 N
     Total Duration: 0.73 s
     Max Duration: 0.2 s
     Fuel Mass: .006 kg

From NAR.org data, reasonable parameters to enter into RocketCalc for an B6 engine would be:
     Average Force: 5.03 N
     Max Force: 8.4 N
     Total Duration: 0.86 s
     Max Duration: 0.2 s
     Fuel Mass: .008 kg

From NAR.org data, reasonable parameters to enter into RocketCalc for an B8 engine would be:
     Average Force: 8.46 N
     Max Force: 12.3 N
     Total Duration: 0.5 s
     Max Duration: 0.2 s
     Fuel Mass: .008 kg

From NAR.org data, reasonable parameters to enter into RocketCalc for an C6 engine would be:
     Average Force: 4.74 N
     Max Force: 10.6 N
     Total Duration: 1.86 s
     Max Duration: 0.2 s
     Fuel Mass: .014 kg

From NAR.org data, reasonable parameters to enter into RocketCalc for an D12 engine would be:
     Average Force: 10.21 N
     Max Force: 20.7 N
     Total Duration: 1.65 s
     Max Duration: 0.3 s
     Fuel Mass: .026 kg

Reasonable parameters to enter into RocketCalc for the Surveyor spacecraft solid propellant retro rocket would be:
     Average Force: 40900 N
     Max Force: 40900 N
     Total Duration: 42.5 s
     Max Duration: 42.5 s
     Fuel Mass: 590 kg
OK, just making sure you were paying attention.

This rocketry calculator requires no network connection allowing you to work offline and use it anywhere.

Link to RocketCalc for Android smartphones

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