It Really Wasn't Close

I agree. I think Elon's team should first consider fabricating a rocket that won't explode when it falls over when landing. This rocket doesn't have to reach the ISS or carry any payload more than the crafts instrumentation. They've already achieved the very difficult task of precisely reaching the platform but as every gymnast knows, sticking the landing is the point of the routine.

the idea is to never topple over especially while you have propellant on-board or you go off like a firework! after thinking about it I can envision a dedicated landing pad that resembles the design of airplane refueling cones , a cone that guides and funnels to a central point once the rocket starts to enter at the top of the channel it can only desend.

That maybe avoiding the goal of landing on a flat surface. I looked a couple of times at the failed landing again and several key points comes to my mind. First the rocket is not vertically descending as the KSP animation implies to be the desired approach. The rocket is moving horizontally as it descends. This will mean a very non-uniform landing load on the three landing legs and the barge underneath. Since your actual landing attempt video is from a camera attached to the barge, a pitching of the barge could easily be what caused it to flip back. I also notice that directional jets at the top seem to be undersized for providing enough torque to correct the alignment. I say this because it looks like the exhaust plumes get blown around much too easily. They are obviously sized properly for the trip down or the rocket would never get close to the barge. but as anyone who has skydived will tell you, it takes less effort to spin while in free fall than to just right yourself out of a chair.

I think its like balancing a broom. it seems easy until it tilts then "saving it" gets tough once the top heavy end moves away from the pivot point, the current design just will fail too often, it needs to be altered.

Ummm... Maybe some credit is in order for this analogy?

Post #3: http://cr4.globalspec.com/thread/100504/No-Cigars-for-Elon

And as every athlete knows, you must bend the knees. The energy has to go somewhere and as crash testing vehicles shows, it is usually off at an angle. To achieve a 'stick' the athlete gives a lot in the knees and proportionately adjusts tension in one leg/foot joint to compensate for the upper end wanting to go off ( down ) on an angle. I am sure the Segway people could design landing legs that keep it up whilst absorbing energy and compensating for uneven terrain.

Jim

Maybe being too simplistic, but why not just use the old method of " parachute to a soft landing, retrieve, and re-use" Why does it have to "hit the barge"??

Can't it just be close enough for pick up?

I agree. I am an advocate of KISS. (not the band but the engineering acronym) In the science fiction movies, a vertical landing was just how rockets were parked before being reused in the same state as the landing. Like the shuttle, these rockets are going to need some significant servicing and refueling after each use. Having a rocket land like somebody just ran the film backwards is certainly really cool, but only really cool.

I don't like the tripod, I prefer 4 feet with vectoring nozzles, similar to a Harrier, divert thrust from the main to the controlled nozzles, it would work far better and is reusable trying to tame a single thrust point and knocking it back to center with additional thrust at the heavy end is not the brightest approach, it will continue to topple!

The prototype (Grasshopper) rocket had four struts and an apparently a lower center of mass than the Falcon. Add to this the complications of a bigger wind load and any lateral movement during final descent to get an even more chaotic condition. Oh here's an added thought. If there is lateral movement and forces being compensated for by the vectored main engine thrust during the final descent, what will happen when ground effects of this thrust comes into play. The vertical portion of the thrust will increase and slow the descent more. Will the lateral portion of this vectored thrust increase proportionally to the vertical increase, I don't think so. Things will continue to fall over.

if you watch shuttle video you can see vectoring is a significant part of steering. I like the idea of vectoring the main nozzle but still having the nozzles near the 4 feet for an even higher level of control( landing only).l. the main would still be used as the primary thrust to control downward forces. the 4 smaller nozzles would provide a small upward thrust but their primary function would be stabilization of the heavy column, I'd entirely ditch the small thrusters on the top and swap their weight to the lower positioned nozzles. wind loads here aren't a consideration if pre-launch wind parameters are respected.

What about the idea of "Bow Thrusters", that large ships use..Maybe put it high on the cone as a revolving nozzle, changing direction in an controlled fan ,rather than as a direct burst, then having to re-counter on the other side if too strong..? It could be an offset force , getting gyro info from below and counteracting above…

I think the idea is to highly control a vertical decent. bow thrusters are for parking, turning, holding position in shifting seas,pushing against a tilting column trying to get it back to center just bothers me

You are totally right, as those same thrusters basically operate in a 2 -d dimensional state. Then, maybe a variable orbital thrust system (3_D), easy to design, but probably very difficult to control, due to the various power level differences…Although, it seems that the base thrust system, being attached to the "Lower center of gravity " specific part of the missile, the top end would need much less thrust guidance since it is very "light", as you are all pointing out. Watching Harriers, and other systems, I do not think think the problem is technical, but a matter of viewpoint of applying the technology. Given Musk's deep Gov't pockets , "They will figure this out." Watch you wallets….

Yeah, as I said in the other thread, just splash the booster, haul it onto the barge and towel it off.

Landing to take off again is too much work for 'cool points.' The shuttle was cool, and we as a public stopped caring about the launches after what, the seventh one? And we stopped caring about the landings after the tenth, only concerned about the disasters after that.

That's how we used to do it with water rockets!

Wow ! A rocket that explodes when landing? Sheer genius! What a tax write off that must be. Now if could get a few things over here to explode when they fall over,,

Actually it was pretty damn close. In Elon's write up of the landing (and visible in the video) they were surprised by the residual lateral speed of the first stage. The thrusters are strong enough but they have to respond really really fast to changes in attitude, especially at touch down where the rocket can have no residual lateral speed. He feels they should have been able to compensate had the throttle valve responded quickly enough. You can see the thruster increasing as the rocket tips over. I guess we shall see in two months.

They have had much success with the prototype "grasshopper" test bed, but that was not screaming through the atmosphere at transonic speed. It simply went up and then down. The Falcon 9 is re entering and then attempting to land on a postage stamp. Since this has never really been seriously tried before, I am inclined to give him a little leeway. I think he is doing a great job and it is on his own dime so as far as I'm concerned he can blow up as many as he wants. Especially considering how many others have tried to resupply the ISS with less success.

Next up (pun) the Dragon Crew cab. LOL

--It is one of the very few things I miss about Florida, seeing rocket launches.--

Land in a hole where the crosswinds are zero!

Dr. Evil's lair in the volcano!

I don't know.

The space shuttle lands on wheels.

The Apollo capsule pops a chute and lands in water.

The Russian capsule pops a chute and sets down on land.

An Estee's rocket pops a chute and lands on Terra firma.

Even the Chinese got it figured out.

Even if it fell over and got bent up, that's gotta be a whole lot easier to recycle then looking for a billion little pieces scattered all over every which way.

Look, I'm just going to come out and say it - why not cut the thrust and safely shut down before landing and change the landing pad to something soft like a retractable net or inflatable bouncy castle or something. Hitting a target has been shown to work after all.

Simple(er).

Like any version of the Windows OS (for example), it doesn't have to be perfectly Engineered to work in real life, as long as it is safe and cheap.

_{Jack - Former NASA subcontractor (Unmanned Mars mission - canceled).}