Electro-static charge and its effect on rocket operation.


Cause and effect

Water rockets are currently predominantly produced using plastic materials PETE

 bottles plastic fins etc. All these materials are relatively easy to charge with static


Subsequently they fly through the air at velocities that can be anything up to 100+m/s

 having been pressurized by a pump with a friction seal piston and possibly a plastic



Potential causes of electro-static charge:

  • Rapidly flowing air over the surface of the plastic rocket surface. (Multiple

 launches would increase this charge unless controlled )

  • Statically charged air from the pump.

  • Rubbing operations encountered whilst manufacturing the rocket.

  • Charge transfer from launcher system.

  • Charge introduced by contact with either an electrically charged ground crew

     or third party such as a car or a television.

    A classic case would be somebody who has just travelled in a car or put on a

     synthetic pullover taken out of the clothe drier that are both highly charged.

  • Proximity to a charged television/computer screen

  • Electrical charge introduced by on board transmitters or electronic circuits

 using batteries.

  • The affects of accumulated electro-static charge can be important in several

 operational conditions:

  • An electro-statically charged plastic parachute canopy will not readily open/

 inflate. The two halves of the parachute remaining stuck to each other . Or fails to

 release from the charged coiffe. The parachute remaining stuck to the inside of the


  • Micro electronics in a highly charged electrostatic environment will not function

 correctly and can be seriously damaged. Electronic instrumentation needs to be

 protected from this type of environment.

Precautions to be taken to avoid significant electro-static charge building up

 on the rocket:


  • Use a good quality electro scope meter and measure the charge seen on the various parts of the rocket body prior and after charging with compressed air.

  • Similarly measure the accumulated charge after each successive flight.

  • Discharge the static electricity using a good earth. This can be created by using

     a metal rod or tube driven into the ground adjacent to the launch site.

    A quick earth can be created using a garden fork stuck into the ground

     adjacent to the launch pad. To which a car battery jumper lead can be


    Alternatively a cold water supply that is always connected to the launcher tube

     can provide a good earth. Check to see that this discharges the launcher. The

     level of charge relative to earth can quickly be determined using a sensitive


  • Connect the earth to the rocket launcher using a good size cable. Using the

 multi-meter to measure the time it takes for the rocket, coiffe or launcher to discharge.

  • Use talc on the surfaces of the parachute and coiffe to prevent direct surface


  • Similarly discharge the ground crew who come into direct contact with the


  • Avoid wearing synthetic clothing.

  • Use natural materials for the launcher system and parachute where possible.

The better the earth the shorter the discharge time. If the earth is left attached to the

 launcher table/tube them it can reduce the level of electrostatic charge transferred to

 the rocket.

Examples of electrostatic electricity can be demonstrated using a balloon rapidly

 rubbed against the fabric of a pullover Too attract hair or stick the balloon to the



Or a plastic comb rapidly rubbed against a sleeve and used to attract small pieces of

 plastic packaging or polystyrene.

Charge build up on the screen of a television or computer discharges through you when you touch it. It also attracts lots of dust particles from the surrounding atmosphere.


To check if a parachute is significantly charged without using a electro scope.

 Suspend the parachute vertically from its cords and see that it is not attracted by

 another object. Curtains, wall etc. If it is attracted the cords will no longer hang in a

 vertical cone and the parachute needs to be discharged.

To reduce the potential electrostatic charge capacity of the rocket avoid using plastic

 materials that have been either heavily rubbed or abraded during manufacture.


In industry where more and more parts are produced from plastics electro-static

 charge is controlled using special surface treatments like 'air plasma'.


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This site was created on the 15th April 2003

 ŠJohn Gwynn and sons2003 

You're welcome to reproduce any material on this site for educational or other non commercial purposes

 as long as you give us proper credit (by referring to "The Water-Rocket Explorer" http://waterocket.explorer.free.fr).