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Provisional Conditions for Air Start and Two Stage Flights

Posted by Tim Rempel on February 13, 2012
CAR-ACF is pleased to announce that the following provisional conditions have been approved by the CAR-ACF Board upon recommendation from the RSO committee. If you have any questions in regard to this, please contact your local board member.

CAR Provisional Conditions for Air Start and Two Stage Flights

These conditions apply to rockets with multiple stages or air-started motors where total impulse is 640 Ns or greater. While staged/ air-start flights of less than 640 Ns total impulse are currently exempt from the following rules, adherence to these rules is suggested as good practice for all such flights.

A rocket must have a reliable means of inhibiting air starts or upper stage ignition if the trajectory deviates by more than 20 degrees from the vertical. Possible solutions include a device that detects the rocket's actual flight angle or a device that is programmed to require the rocket to reach a minimum altitude by a set time. Other methods may be acceptable, at the RSO's discretion.

For all electronic interlock devices, the flier shall document and present the operating principles, the programming and the wiring to the RSO's satisfaction.

Maximum deviation from vertical shall not exceed 20 degrees. The launch RSO may require tighter tolerances in order to ensure the sustainer remains within the launch range.

A flight simulation acceptable to the RSO shall be presented to the RSO prior to approval of a flight. Fliers who use the time to altitude method shall demonstrate an understanding of the trigonometric solution.

At the present time, the following devices are known to satisfy the above requirements: Rocket Tilt-o-Meter (detects flight angle); Raven (programmable events if altitude is reached before a time limit); UFC3 (same as Raven). These are listed as examples only - other devices may exist, or may be released in the future, with similar capabilities.

No 'sparky' motors are allowed for two stage / air start flights.

Approval of all flights remains subject to the launch RSO's discretion.

These conditions are subject to review after one year, or sooner if needed.

CAR Guideline for Electronics and Short Burn Motors

Some, mostly older design altimeters and staging devices are not designed to detect very short periods of acceleration. These devices must not be used with short-burn motors.

An example is the old Adept 231 series - minimum acceleration time to detect liftoff is 0.3 seconds. If a motor burns for less than this time, the device will not "see" liftoff and will not function.

All fliers are responsible to ensure they use compatible electronics with their motor selection.

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