Rocket Ejection Charge Calculator/de

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Führungsschiene
FalschirmGrößenRechner
Arbeitsbereich Rocket

AusstoßLadungsRechner

Menüeintrag
Rakete → Rechner → Ausstoß-ladungs-Rechner
Arbeitsbereich
Arbeitsbereich Rocket
Standardtastenkürzel
Keiner
Eingeführt in Version
0.19
Siehe auch
Keiner

Beschreibung

Dieser Rechner gibt nur eine Schätzung der benötigten Pulvermenge. Zu viel oder zu wenig Pulver kann zu einer fehlgeschlagenen Bergung oder zu Schäden an der Rakete führen. Teste die Rakete vor dem Flug IMMER am Boden.

Der Auswurf erfolgt, wenn die Kammer, in der sich das Bergungssystem befindet, mit ausreichender Kraft unter Druck gesetzt wird, um das Bergungssystem aus der Kammer auszustoßen. Die erforderliche Kraft kann aufgrund einer Reihe von Faktoren variieren:

  • Durchmesser und Volumen des Rumpfrohrs
  • Masse der Nase und des Wiederherstellungssystem
  • Ausstoßverfahren, beispielsweise Kolbensysteme erfordern weniger Druck
  • Vorhandensein von Scherstiften zur Verhinderung von Schleppablösung
  • Passform des Wiederherstellungssystems im Rumpfrohr

As such, this calculator will only give you a starting estimate. Too little powder will result in a failed ejection and a failed recovery. Too much powder may result in damage to the rocket or recovery system, which may also result in a failed recovery. It is ALWAYS necessary to do a ground test before flying your rocket.

When calculating the volume of the body tube, it is rarely necessary to include the full length. For example, the shoulder of the nose or electronics bay may consume some volume. Adjust your length specification accordingly.

There are some rules of thumb that can be applied based on years of experience from multiple rocket builders. Of primary concern here is the force applied to the ejectable portion, typically the nose cone or electronics bay. Ejection forces at this interface should be between 150 and 200 lbf (~667 to 890 N). The pressure required can then be calculated based on the volume of the chamber. This pressure will be less for larger diameters and more for smaller diameters. There are presets in the calculator to set these forces (low and high settings in the combobox).

Ground testing should start at the low end of the recommended range to prevent damage to your rocket. Increase the amount as required to ensure safe recovery.

Anwendung

  1. There are several ways to invoke the command:
    • Press the Ejection Charge Calculator button.
    • Select the Rocket → Calculators → Ejection Charge Calculator option from the menu.
  2. Enter the weight of your rocket and parameters for your parachute.

Berechnung

Pressure is set by desired force, or force can be set by specifying the desired pressure. This is based on the force applied to the area at the end of the volume to be pressurized.

P=Fπ(D2)2

where

F= desired force
D= body tube diameter

Once the desired pressure is known, the amount of black powder can be calculated using

m=PVRcTg

where

P= the pressure calculated in the previous equation
V= the volume of the chamber to be pressurized
Rc=12.1579mK, combustion gas constant for FFFFg black powder
T=1739K, combustion gas temperature
g=9.807ms2, acceleration due to gravity

Einheiten

Calculations are done using metric units, but will display in your preferred units. Values can also be entered using any supported units by including the units with the value (eg 5 oz, or 23.2 g)

Referenzen

  1. http://vernk.com/EjectionChargeSizing.htm
  2. https://www.insanerocketry.com/blackpowder.html
  3. https://rocketrycalculator.com/rocketry-calculator/bp-estimator
  4. http://www.rockethead.net/black_powder_calculator.htm
  5. http://hararocketry.org/hara/resources/how-to-size-ejection-charge/


Führungsschiene
FalschirmGrößenRechner
Arbeitsbereich Rocket


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