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  #1  
Old 01-18-2011, 11:28 AM
Beowulf Beowulf is offline
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Question Precision Launch Pads?

After our flight on Saturday , I am very interested in building a launch pad that allows for more accurate targeting than our basic Estes one. I have an old german equatorial mount, to which I am thinking about attaching a platform. The idea is that I could adjust the tripod to level the pad, and then set the launch angle and direction using the mount.

What I'd really like to be able to do is to enter the current environmental conditions into an application and then use the calculated rod deflection and direction in order to return the rocket close to the launch pad. Heck, if I could make it land back on the rod, then I would!

My question is this: has this type of project been done before? I don't see a similar thread having been posted previously, which leads me to suspect if such a thread exists, that it has been archived. Either that, or the idea itself is folly. What do you all think? Thanks for your feedback!
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Old 01-18-2011, 11:50 AM
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GregGleason GregGleason is offline
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Were it not for the atmosphere, it would be a fun project. What I mean by that is that winds aloft and wind shear wreak havoc with flight profiles, and therefore have a lot of "say" on where a rocket lands. It might be a fun science fair project in NASA's VAB, since you do not have the wind influence (when the doors are closed) that you have at a more typical launch.

More often than not, when I have left the launch rod toward dead-center, it's a better flight. For me, things sometimes have gone awry when I begin tilting the rod.

Greg
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Old 01-18-2011, 05:23 PM
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Many times, the wind at ground level and just above the tree line are a bit different. Causing a rocket to either veer off course (most notably the sci-fi Viper) or the chute to carry it several blocks more than planned...
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Old 01-23-2011, 10:32 AM
Beowulf Beowulf is offline
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Wink

Thanks for the comments. I realize that the wind at higher altitudes is going to be different than that at the launch site. It also occurs to me that wind is three dimensional: it won't exert a purely orthogonal force to the flight of the rocket.

However, I was thinking that I could project where I thought the rocket would land, and then use a GPS to mark the actual landing site. The difference between the two would be a combination of two factors: environmental effects, and then imperfections in the build of the rocket itself. I was playfully thinking of the latter quantity as "rocket fudge."

Over consecutive launches on the same day, environmental effects might be consistent enough to include as rough estimates. I'm not expecting to predict the exact spot in which the rocket will land, although I do think it would be cool to have a contest to accurately predict the landing site. If I could bring the rockets down within 50 yards of the launch site, then I think that would be a success.

I'll update this thread with my progress. It could still be a fool's errand, but at the moment it's very intriguing for me!

Last edited by Beowulf : 01-23-2011 at 11:10 PM. Reason: spelling
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Old 01-23-2011, 09:13 PM
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Please post the results. My guess is that the lower the impulse, the tighter the CEP will be.

Greg
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Old 01-24-2011, 12:03 AM
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Mark II Mark II is offline
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I think that this is more art than science. You develop a feel for where your rockets will land based on your knowledge of the specific field, your experience launching rockets in it under various conditions, and your experience launching your specific rockets with various motors. It all gets combined and processed in your brain to produce something akin to an intuitive feel for the process. I wish it could be reduced to a set of equations, I really do. No expert system or artificial intelligence ever invented has ever had anything like the information processing power of the human brain, nor has any technology ever had anything approaching the incredibly tight coordination of eye, hand and mind. The quadrillions of computations that are executed between our ears every second take place at a level just below consciousness, and they produce results that we perceive as intuition and experience-derived knowledge. I suspect that the most successful predictions of the landing spots for our unguided model rockets will be achieved through the use of these stupendously powerful tools.
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Old 01-26-2011, 02:18 PM
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Though the capability may bother some, I have always been fascinated by the possibility of combining a steerable parachute, a GPS receiver and a microcontroller.

Such a system is not likely to be good enough to guarantee a win in spot landing, but it will lessen wind drift and can be programmed to try to avoid hazards such as roads, clumps of trees or bodies of water.


Bill
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Old 01-26-2011, 02:46 PM
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How about a Gemini Titan with an RC Rogallo wing capsule recovery system? Naturally you'd need to have the scale recovery skids for full fidelity points. If things got ugly during glide recovery you could eject the scale astronauts out of the capsule using some Quest 'freeps' in the ejection seats.

I guess NASA planted enough of their boilerplate capsules in the desert during development that they stuck with parachutes and a water recovery. That doesn't mean we have to!!
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Old 01-26-2011, 03:35 PM
Beowulf Beowulf is offline
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Quote:
Originally Posted by pterodactyl
How about a Gemini Titan with an RC Rogallo wing capsule recovery system? Naturally you'd need to have the scale recovery skids for full fidelity points. If things got ugly during glide recovery you could eject the scale astronauts out of the capsule using some Quest 'freeps' in the ejection seats.

I guess NASA planted enough of their boilerplate capsules in the desert during development that they stuck with parachutes and a water recovery. That doesn't mean we have to!!
I was about to say that your suggestion didn't really fit with my idea of a "precision launch pad," but then I saw Bill's post above. Your idea is a bit outside of my budget!

I have to admit that I briefly considered adding RC servos to an Estes SR-71 rocket and eschewing parachute recovery altogether. That's a completely different project.
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Old 01-27-2011, 01:05 AM
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blackshire blackshire is offline
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Quote:
Originally Posted by Beowulf
After our flight on Saturday , I am very interested in building a launch pad that allows for more accurate targeting than our basic Estes one. I have an old german equatorial mount, to which I am thinking about attaching a platform. The idea is that I could adjust the tripod to level the pad, and then set the launch angle and direction using the mount.

What I'd really like to be able to do is to enter the current environmental conditions into an application and then use the calculated rod deflection and direction in order to return the rocket close to the launch pad. Heck, if I could make it land back on the rod, then I would!

My question is this: has this type of project been done before? I don't see a similar thread having been posted previously, which leads me to suspect if such a thread exists, that it has been archived. Either that, or the idea itself is folly. What do you all think? Thanks for your feedback!
This could be the seed of a fascinating NAR Research & Development contest category entry. You could use the same "wind-weighting" equations that are used to aim the launchers of full-scale unguided sounding rockets so that the rockets will land in desired impact areas. As the folks at Wallops Island, White Sands, Woomera, and other ranges do, you could collect pre-launch wind data from a ground-based portable anemometer and acquire "winds aloft" data by tracking the motions of released helium balloons. (The "big boys" sometimes botch their "wind-weighting"--the second British Skylark sounding rocket veered far away from its assigned impact zone on the Woomera Range in Australia because the launch crew accidentally skipped one of the equations that they used to compute the rockets' trajectories based on the winds aloft!)
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