Reply to post: Launch rail and backplate issues

LOHAN ideas..

Anonymous Coward
Anonymous Coward

Launch rail and backplate issues

A couple of issues occur to me regarding the use of a launch rod and backplate, at least as shown in the Reg diagrams.

Re the launch rod: First, whilst using a Teflon insert that completely encircles the launch rod to reduce friction seems like a good idea there are a couple of potential problems with this. The major problem is that if anything sticks to the launch rail, from ice build-up due to frozen condensation to tiny bits of grit, then by completely wrapping the launch rail with the insert you've maximised the surface area where anything stuck to the launch rail can jam against it.

A better idea would be to use just two long and thin strips (thin to minimise the swept area and long to bring the contact area back up enough to lower the contact pressure), angled about 45 deg either side of vertical, at the top of the hanger loops (and if you were to go this way then you should also cut/trim them so that they come to a point at the front, giving them a chance to divert anything stuck to the rod around them or, alternatively divert them around anything that won't shift)

An even better idea though, would be to ditch the cantilevered launch rail entirely and just use some curtain rail, which could be attached along its entire length, with a couple of roller glides which would roll over anything but a catastrophic build up of crud. Make sure you completely degrease the rail and roller glides though; any lubricant is likely to freeze and jam (this was a trick learned by photographers in the arctic/antarctic, where the lube in their cameras was prone to freeze)

Re the backplate: This is a _really_bad idea. Y'know rockets work by equal and opposite reaction? Well the rocket will go forwards because of all the stuff it's chucking out the back but all this stuff coming out the back will hit the backplate, forcing it and the entire truss backwards. However, because the truss is suspended from above what will happen is that the truss will pivot backwards, swinging the launch rail downwards just as the plane is moving along it.

Do away with the backplate entirely and just use a 'stop' on the launch rail to hold it in place and prevent it dropping off the end.

Oh yeah - re the plane swinging about uncontrollably in the wind: won't this only be an issue at low altitudes? I thought that high altitude winds were relatively 'smooth' and not very turbulent, so just launch when the low-alt weather is fairly calm; once it gets up high it'll be moving _with_ the relatively un-turbulent air.

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