322 2) At the point of contact between the boom arms and the boom wraps, friction needs to be minimized to  allow the booms to glide past each roller. Excess friction will exacerbate ‘blooming.’ Early on in the  design cycle, the rollers where exchanged from nylon,  as was heritage with NanoSail -D, to Rulon J  PTFE.   3) Adding f riction between boom wraps decreased the ability for the booms to expand radially. This  method was first noted by the LightS ail-A design team. In order for the booms wraps to expand radially  and cause ‘blooming’ they must slide past one another. By increasing the friction between the boom wraps this sliding is made more difficult , helping to alleviate blooming. This was shown to work with  TRAC booms by scratching the surface with medium -grit sand paper .  4) Increasing contact and friction between the spool flanges and boom wrap aids deployment . By having  one or both flanges directly contacting the boom wraps ‘blooming’ can be impeded to a small degree. It is desirable to minimize any extra height between the flanges.   5) Increasing the packaging efficiency of the rolled  boom pair will also aid in a successful deployment.  Tighter packing can be achieved by pulling the booms outward as they are being spooled inward.   6) Reversing deployment  at intervals can assist in deployment when ‘blooming’ does occur (e.g. , for  every 1 m deployed, reverse 10  cm and repeat). If the boom begins  to expand radially, reversing  direction will tighten up the spool eliminating momentary blooming. It was shown during prototype  testing that the boom wraps will constrict inward before retracting the boom back into the deployer.   7) Adding points of contact at the boom arm significantly alleviate ‘blooming.’ As pictured in Figure 13,  by adding a rocker -bogie to the boom arms, we can double the points of contact from four to eight and  decrease the contact at each point by half. This method has been shown through testing to be one of the most effec tive techniques in reducing ‘blooming.’ Furthermore, if ‘blooming’ does occur, th e rocker - bogie motion has proven to handle the oblong rotation of the boom spool without binding. The rocker - bogie simply rotates back -and-forth around the bulged section of the boom  wrap , where the single  roller would come into contact with t he bulged section creating a large tangential force. This tangential  force would cause a spike in the required  motor torque, which causes  failure. Unfortunately this rocker - bogie design is unable to fit in the NEA Scout design volume.  

Figure 13.  Deployer Prototype with Added Rocker -Bogie Rollers   These approaches  are also applicable to other boom  systems . In fact, during the development of the NEA  Scout  boom deployer, very slight modifications were made to allow for a sp lit tape composite boom (Figure   14). The spl it tape composite boom spool ed tighter and deploy ed with greater ease than the metallic TRAC   boom. The improved deployment of the split tape composite boom when compared to the metallic TRAC  boom can be attributed to 1) significant decrease in strain energy (comparable to force required to flatten  the boom, 2) friction between boom wraps, and 3) ability to package into a tighter roll.   Rocker -Bogie Rol lers