Well crap, I got the wrong make :(

Four comments in, and this discussion is effectively over.

Yes, random mutations happen randomly. Sometimes they happen in hospitals using antibiotics, but usually they happen anywhere else. Sometimes, those mutations happen to survive long enough to become widespread through a population. Sometimes that population is isolated, and the mutation becomes common. Sometimes a particular antibiotic (natural or synthesized) affects the balance of variants in the population.

Very rarely, we humans have suitable circumstances to actually notice.

what we're saying is that arranging for velocity AND position to be 'null' at the same time is harder than simply arranging for velocity to be null and position to be +/- 100m(or so).

*Sigh*
 
I understand what you're saying - but as with my previously reply, you don't grasp the problem.
 
The appearance of the vehicle "working hard at the last second" during the first attempt was a consequence of running out of hydraulic fluid - and would have occurred regardless of the size of the target. The appearance of the vehicle "working hard at the last second" during the last attempt was a consequence of the throttle valve not operating to spec - and would have occurred regardless of the size of the target.
 
From the point of view of the final landing sequence it's not all that much easier to arrange for velocity to be null and position to be +/- 100m than it is to arrange the same +/- 1m. Selecting a landing point occurs at a relatively high altitude (and on a, relatively speaking, relaxed timeline) and final trim starts around a kilometer or so up (AIUI). From there, jittering the variables (burn time and timing, gimbal angles, and throttle settings) a tiny amount one way or another to maintain targeting isn't a substantial burden (on the software or the hardware) compared to the much larger problem of nulling your velocities.

You're talking about some kind of articulated arm (which can survive being essentially inside rocket exhaust)

I think you're picturing something different. I'm picturing something pretty big that comes in from the sides, staying well away from the exhaust.

That just makes an already heavy, complex, and expensive system even heavier, more complex, and more expensive than I envisioned.

Despite the common misconception, there is actually no general legal requirement that corporations must act to the benefit of their shareholders. Rather, United States law holds only that the company act according to its charter, which may actually have practically any terms the founders see fit. There may be no terms, permitting executives to have free reign over the company, or there may be very restrictive terms detailing precisely how the corporation is to be run, which is particularly useful for incorporated charities.

With that out of the way, why should there be any question about giving away anything for free? I can't recall any large company whose marketing department didn't get a wide variety of samples or freebies to promote the brand. For anything with an engineering department, the offer to make an expensive system work with other expensive systems has been a common sales tactic. These ideas are not new or questionable at all.

Also falling into the "not new" category is Microsoft's ongoing strategy. For the last two decades, Microsoft's primary business model has been to attach their products to existing business dependencies, encourage their use (forming new dependencies), then drop support for the original dependencies in favor of their own new products, leaving their own product as the only upgrade path for a now-locked-in customer.

For several years, Microsoft has clung to a few bad decisions (most notably ignoring the Internet until it was too late, then ignoring the business need for easy provisioning), leaving room for open-source solutions to grow. Having now completed their compatibility phase, Microsoft moves on to encouraging their products' use. A low initial price tag helps that effort.

Reading through TFA, the justification seems to be that Microsoft contributes to a large number of open-source projects:

In other words, Microsoft is still Microsoft. They've firmly established the "extend" part of their usual strategy, and now it's time to start slowly dropping support for those old, outdated open technologies in favor of the newest crap spewing forth from Redmond.

It's like how a real terrorist would not joke about a bomb at an airport. But someone who does is detained or arrested, and time is spent by TSA that could be better spent looking for real terrorists.

I studied and tutored experimental design and this use of inferential statistics. I even came up with a formula for 1/5 the calculator keystrokes when learning to calculate the p-value manually. Take the standard deviation and mean for each group, then calculate the standard deviation of these means (how different the groups are) divided by the mean of these standard deviations (how wide the groups of data are) and multiply by the square root of n (sample size for each group). But that's off the point. We had 5 papers in our class for psychology majors (I almost graduated in that instead of engineering) that discussed why controlled experiments (using the p-value) should not be published. In each case my knee-jerk reaction was that they didn't like math or didn't understand math and just wanted to 'suppose' answers. But each article attacked the math abuse, by proficient academics at universities who did this sort of research. I came around too. The math is established for random environments but the scientists control every bit of the environment, not to get better results but to detect thing so tiny that they really don't matter. The math lets them misuse the word 'significant' as though there is a strong connection between cause and effect. Yet every environmental restriction (same living arrangements, same diets, same genetic strain of rats, etc) invalidates the result. It's called intrinsic validity (finding it in the experiment) vs. extrinsic validity (applying in real life). You can also find things that are weaker (by the square root of n) by using larger groups. A study can be set up in a way so as to likely find 'something' tiny and get the research prestige, but another study can be set up with different controls that turn out an opposite result. And none apply to real life like reading the results of an entire population living normal lives. You have to study and think quite a while, as I did (even walking the streets around Berkeley to find books on the subject up to 40 years prior) to see that the words "99 percentage significance level" means not a strong effect but more likely one that is so tiny, maybe a part in a million, that you'd never see it in real life.

You're not getting what he was saying.

I do get what he's saying. What neither of you seem to grasp is that the size of the target isn't as relevant as you think, because you have to null your horizontal velocity regardless of the size of the target. It doesn't matter whether you're stopping on a postage stamp or anywhere in a given block - either way you still have to stop. It's the stopping that's problem, not the deciding where to stop. Stopping is very difficult for the Falcon 9 because it's T/W ratio is so far out of the optimal range and a larger target area won't make it all that much easier.
 

Though if they're that good at targeting, maybe programming up an adaptive 'catcher' robot would work? I'm thinking of something along the lines of 3 arms that have a range of motion, and when the rocket's within a few feet, they gently 'grab' the rocket using shaped and padded interfaces(I'm picturing a semi-circle matching that of the rocket) and provide stability.

That's "good at targeting" a couple of orders of magnitude better than what they've demonstrated to date (which is, pardon my french, already pretty fucking amazing). You're talking about some kind of articulated arm (which can survive being essentially inside rocket exhaust)... Which is, quite frankly, makes things much harder and more complicated and introduces a metric buttload of additional possible points of failure. Much easier to simply re-engineer the throttle valve.

IMHO, if more of the horizontal velocity was shed earlier, It'd be easier to stay balanced at the end.

At the cost of increasing the difficulty of targeting the landing, and still having to null any horizontal velocity due to the wind. TAANSTAFL.

The rest of what you say is generally true, although a larger target *would* help. The advantage of a larger target is that, while you still have to zero your horizontal velocity, you don't have to zero it anywhere terribly precise.

Yeah, you do. Given the narrow footprint and the low CG of the vehicle, if the horizontal velocity wasn't as close to zero as you can get at touchdown - it's very likely to tip over. (Even if you don't damage the landing legs in the process.) The upper part of the vehicle isn't heavy, but it has a very long lever arm.
 

You can pick an optimal set of thrusts that results in the correct orientation and velocities (horizontal and vertical) without worrying overmuch *where* that series of thrusts has you touching down.

In the end, that makes far less difference than you think because while you can reduce the amount of horizontal velocity that needs to be nulled you cannot eliminate it. (Not without launch criteria that include "near zero wind at the recovery site", which is beyond impractical.) The result is, with the current vehicle, you still have to null horizontal velocity at the last second before touch down. The basic problem is that the vehicle is badly designed for what it's being asked to do.
 

. Both attempts so far clearly demonstrate the ability to do an excellent good job of targeting a (relatively) tiny barge, but currently, if the rocket would come down even 100' (30m) to one side of its target spot, it needs to induce a horizontal momentum (which requires leaving a vertical attitude as well, it can't just translate sideways) and then null that momentum at the right moment (and fix its attitude). That's hard.

Both times they've hit the barge almost dead center - I fail to see how that's an arguement for a larger landing area since neither failure was caused by the landing area being too small. Both vehicles would have crashed regardless of the size of the landing area due to control system failures. (Attitude control on the first, throttle control on the second.) That's what neither you nor the OP seem to grasp.

Kind of makes me wonder if using the barge as such a small target is contributing to the hard landings, simply because it's such a tiny target relative to the area that the rocket has to come down on

Since the first attempt hard landed because it ran out of attitude control gas, and the second hard landed because of a control valve problem... how would a larger target have helped? In case of the first attempt, you've still got to control your attitude regardless of the size of the field. In the second, the size of the field is irrelevant if you can't properly control the vehicle in the first place.

Seriously, don't be misled by the frantic activity in the final seconds of the most recent attempt. That burst of activity was the vehicle attempting to null it's horizontal velocity and then trim it's attitude before landing - something it has to do regardless of the size of the field.

The basic flaw in the landing sequence isn't the size of the target, it's the design of the vehicle. Its minimum T/W ratio is well over unity at landing, meaning it can't hover, can't ease itself down, and you have to take great care to not end up with positive vertical velocity. The only way it can land (with any reasonable sized target) is to approach at high speed, then at the last second try to null horizontal velocity without excessively reducing vertical velocity (I.E. bouncing), followed by a return to vertical and touchdown.

You could avoid this by having a circle of paved ground a quarter to half a mile in diameter - but that's not cheap to build or maintain given the need to resist a rocket's exhaust. Long term, given that the tests are essentially free*, it's cheaper and easier to figure out how to land precisely on a smaller target.

* The first stage is bought and paid for by the launch customer - and so long as the added equipment for landing poses no undue risk during ascent, they don't care what happens to it after separation.

If you can convince the government that your open-source project should fall into the 501(c)(3) category (which will involve a good deal of paperwork on your project's behalf), then yes.

I'm not sure. Ask a lawyer and/or tax professional.

It sure seems that if a larger landing area was available, so that the rocket didn't have to lean so far to adjust to a very small target and thus could prioritize staying vertical, it would be able to land successfully.

No so much as you might think - you still have to trim and eventually null your horizontal velocity, and null any horizontal residuals arising from trying to remain vertical. It's a complicated problem, even if you're just aiming for an arbitrary landing spot in a larger landing area.

On top of that, the crash seems to have been caused not by prioritization, but by a control valve operating sluggishly causing the response time to go out of limits. Even if you're just accepting a landing wherever you're coming down, if the control system gets out of phase you're screwed.

My opinion was always that Wikipedia should be treated as a single interview with an expert in a field. It is generally accurate, but almost certainly wrong on a few details, that other unrelated sources should be used to verify.

From that perspective, it's certainly a good starting point for learning about the "unknown unknowns" in a field, and getting a path for further study. It might even be suitable as the main source for a select few kinds of research.