RAFT HF Antenna Deployment Test                           25 Mar 2005
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The initial test of the HF antenna spooling deployment system failed to fully deploy the antenna.  The separation of the two spacecraft only achieved a 2 foot separation instead of the required 12 foot separation on the initial, quickly improvised low-friction track test.  The following plan of action will be taken to resolve this initial test:

* Quantify the limitations of the test compared to zero-G reality
	- Measure track friction and assess test qualifications
	- eliminate launcher spring from test, use sep springs only
	- improve test fidelity

* Quantify the spool system friction
	- develop test apparatus to better measure spool drag friction
	- We had used 40g as design basis.  What is actual?
	- refine model to match failed test for better understanding

	
* Re-evaulate design details
	- eliminate the 15 degree offset with smaller spool
	- trade-off smaller spool with increased wire bend radius drag
	- allow more gaps in windings (shorter antenna)
	- determine friction contributions
	- evaluate using teflon to reduce friction

* Re-evaluate mission requirements
	- shorter antenna length

* Increase spring separation force
	- re-evaluate separation velocities from shuttle
	- design for minimum of 1 foot per second
	- evaluate doubling spring force with springs in opposite pockets
	- find alternate springs
	- eliminate brass housing for larger diameter

We have confidence that success can be achieved.  At least a 9 fold improvement is required to assure success with a 1.5 safety margin.  Here is a possible budget of improvements in descending order of preference:

50% reduction in friction using teflon and better geometry
Doubling of spring force
10% improvement in test fidelity
10% factor allowed for 1-G test losses
50% improvement by shortening antennas to 3' instead of 6 feet

Bob Bruninga
USNA Satellite Lab
410-293-6417