[AR] Re: "How Hard Can It Be" rocket episode
- From: Henry Spencer <henry@xxxxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Sun, 17 Nov 2013 15:34:45 -0500 (EST)
On Sun, 17 Nov 2013 johndom@xxxxxxxxx wrote:
> > the Ranger landers had solid retros that decelerated them to fairly low
> > velocity before impact.
>
> Fairly low velocity is relative. For Ranger impact probes made of balsa wood
> their lunar impact velocity after retro braking still was at least an order
> of magnitude larger than the impact velocity of the amateur rocket in "How
> Hard.Can It Be" landing without a chute.
Don't know what the number for the latter is, but the maximum impact
velocity specified for the balsa-sheathed Ranger hard-lander capsule was
250 ft/s (about 75m/s), which is not that high as a terminal velocity on
Earth.
> The issue here: by what means could such velocity be neutralised on impact
> (over here) if the chute did not deploy. To save the electronic data.
Same approach, really, as the Ranger capsule: you need a crushable shock
absorber, so the deceleration takes place over tens of centimeters rather
than (worst case, hard surface) a few millimeters. Modern electronic gear
is pretty tough but there are limits.
Henry Spencer
henry@xxxxxxxxxxxxxxx
(hspencer@xxxxxxxxxxxxx)
(regexpguy@xxxxxxxxx)
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