Mercury LES orientation?
 

I've looked at dozens of photos of the Mercury Atlas capsules and LES assemblies--both real and models, and I can't quite determine the correct orientation of the LES fuel tank to the capsule (Schirra's Sigma 7 specifically.)

Any help would be appreciated!

VR, Jeff

Well,for one, that's not a fuel tank. It's a casing for a solid rocket motor that has three nozzles.

There is a drawing set by David Weeks, from RealSpace models, about Mercury and the rockets that launched it. But I’m not sure if the escape rocket is shown in enough detail for what you are looking for.

http://www.realspacemodels.com/draw...ury-drawing-set

Do Google IMAGE searches searches such as this for mercury with these keywords: "mercury escape tower"

https://www.google.com/search?q=mer...iw=1002&bih=478

One of the hits is for this photo, from: http://www.americanspacecraft.com/pages/mercury/ba.html



And this one (which is a 1/1 model) from: http://www.americanspacecraft.com/p.../merc_pens.html




or “Mercury Spacecraft Drawing": https://www.google.com/search?q=mer...1.0.PXhlKr-6q7U

Also, BTW, John Pursley's Mercury Redstone model in exquisite detail: http://www.accur8.com/NARAM44_LibertyBell.html

As well, James Duffy is an expert on the Little Joe-I, which of course flew several Mercury spacecraft with Escape Rockets. Some things might have been a bit different for Mercury Atlas launches such as Sigma -7 ,but most would have remained the same.

BTW - here's one pic from John Pursley's Accur8 site: http://www.accur8.com/NARAM44_LibertyBell.html

This is his MODEL, not the real thing!

Thanks! I think that will work for me.

Also, I didn't know that was a solid propellant in the LES. I learned something today.

Good stuff, George. Thanks for sharing.

BTW, John Pursley presented at my first ever NAR event, a NARCON in Dallas, back in 2000, IIRC. (Met Bunny there, too :)) John was showing how his 4" Mercury Redstone "sun seeker" worked. Way cool !

Doug

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BTW - John Pursley's gimbaled engine guidance did not use sun seeking.

IIRC, he used a combination of "horizon sensing" from an early model plane autopilot and model plane gyros. Or perhaps only the horizon sensing. That was different from sun seeking as sunseeking flies towards the sun unless it is a cloudy day. Which is really bad for a gimbaled engine system since the rocket motor is already angled at ignition (I realized this the hard way in 1989, and the best flight I had was an overcast day when the sun seeking guidance flew the gimbaled rocket mostly vertically).

With horizon sensing, the side-looking sensors can tell if the rocket is off-vertical, assuming that the horizon is level on all sides. This could sometimes be a problem for a gimbaled rocket taking off with tall trees on one side and clear ground on the other side. But I don’t even think that exists anymore because….

These days, the best way to do guidance is to use flight controllers much like those used for Multicopters. The Eagle Tree Guardian is meant for use as model plane autopilot, similar kind of 6 degree of freedom sensor and inertial system. So it “remembers” which way is up and tries hold the model plane level (or a rocket vertical). It’s been used for rocket guidance a few times, works great. And some of the user-configurable multicopter fight controllers can be set up to do the same kind of thing, to control servos for steering as opposed to commanding motor speeds for rotor thrust control (such as controllers that run Ardupilot or CleanFlight, which are open-source). The typical controller inside of ready-to-fly multicopters are not capable of being reconfigured like that (other than perhaps some special “racing drones” that might run Cleanflght or similar software).

Yes, that was it. Thanks for the clarification.

Doug

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