The SkyClimber

[jimfromnsf]

". When you travel over 100 million miles to get there it would be nice to land at the landing site instead of 20 kilometers away....."<br />MSL can do that already.

 

[rlb2]

<font color="orange">MSL can do that already.<font color="white"><br /><br />Wrong. They only warrantee that they can get to within 6 kilometers.... <br /><br /><font color="orange">Try to explain why a world class organization like JPL chooses to not use more parachutes<font color="white"><br /><br />They never had time yet to look this proposal over and give it the good peer review that it deserves, I’m done here…. <br /><br /></font></font></font></font> <div class="Discussion_UserSignature"> Ron Bennett </div>

 

[jimfromnsf]

Yours can't better it, since it won't work. The payload can't lead the chute. That's why there is steerable chutes. Here is another hole in your propoal: A steerable chute would be lighter and less complex than wings on the payload <br /><br />Still waiting for your answer to the JPL question?

 

[j05h]

<i>> ...wings on the payload...</i><br /><br />I noticed that in the viewgraphs. Umm... say what? Any idea beyond "it looks cool"? I can't imagine it helping any. There are many types of steerable parachutes and the little winglets dont' seem like they would add jack to descent characteristics.<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[jimfromnsf]

"They never had time yet to look this proposal over and give it the good peer review that it deserves,"<br /><br />You are diluting yourself if you think this warrants a JPL peer review. <br /><br />Like I said, why do you thinK JPL doesn't use a parachute to provide more braking, when it would clearly would be a better way to go? Because it is not possible.<br />

 

[rlb2]

<font color="orange">I saw some people talking to you after the presentation including the guy from Space Daily is he going to publish it.<font color="white"><br /><br />Thanks I had a better reception than I expected for being in a room half-full of rocket scientist, had a good time - saw Buz again at the conference. Yes I did get approached afterwards by several different people and we exchanged cards but right now that’s all I can tell you. As talked about in my presentation we are mainly developing this for use on Earth and are examining different types of approaches including recoil like devices, flywheels, energy recovery systems such as are on Hybrid car etc, etc, etc. went to the Mars Society Conference because we think it can work on Mars and I have some old friends who visit there every once in awhile.</font></font> <div class="Discussion_UserSignature"> Ron Bennett </div>

 

[j05h]

<i>> Everything that went to Mars and landed safely used a parachute to help slow it down. </i><br /><br />The key is "slow it down". Parachute-only landings are impossible/veryhard on Mars. Terminal descent with a parachute is still fast - hundreds of kph fast. It still requires retro rockets of some kind, and possibly other measures such as air bags. <br /><br />At the datum, Mars' atmosphere is 1% the density of Earth's atmosphere. The issue as I see it is one of the force of the SkyClimber's acceleration causing the parachute assembly to collapse. Solid retros (ala Pathfinder or Soyuz) are well understood tech, and Mars tested. The winch and cable (hundreds of feet/meters) to support an MSL-sized payload is almost guaranteed to mass more than braking rockets.<br /><br />For current projects like MSL or small rovers, the "skycrane" or Pathfinder-type airbags/retros/chutes makes sense. Phoenix is using chutes and retros, no airbags. <br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[jimfromnsf]

"estreet says - no that is way wrong when using more than one chute."<br /><br />Actually, you are wrong and josh is right. <br />Engineers come up with this stuff<br />Mars' atmosphere is too thin to land with parachutes. More chutes doesn't help<br /><br />It doesn't take a rocket scientist to see that no Mars lander has used parachutes to land. Retro rockets and airbags have been used. Explain that <br /><br />Your MSL data is wrong. MSL is going mach 2 when the parachute is deployed and it jettisoned a 1500m at around mach 0.5. And it only has one chute

 

[jimfromnsf]

"estreet - You both must come from the same mother."<br /><br />If we are going to play this game, <i>***Ad Hominem Deleted***</i><br /><br />I am an engineer(vs "I are an") working on MSL. More chutes don't work, retrorockets are better.<br /><br />Also, his chutes aren't supersonic. He can't get to 70km/hr. Also 70 km/hr is too quick for a winch. So his concept doesn't work. <br /><br />it doesn't take an engineer to figure out parachutes don't work, since ESA, NASA and the Russian's don't use them

 

[thereiwas]

A lot of the interesting sites on Mars are several km <i>above</i> the datum. Really thin air up there. This latest Phoenix mission is not going to any of those, but old (maybe) sea bottom, several km below the datum.<br /><br />Who has the equation for those deceleration curves in the Braun and Manning paper on Mars reentry? (I want to play with some radical low-beta ideas.) A weakness in current approaches they point out is that the parachute designs in use today are the old Viking design with a single disk+cylinder chute. They said the necessary testing to develop new hypersonic parachutes is quite expensive. <br /><br />estreet, you have to present backup data for your technical arguments. The moderators have declared that discussing whether or not Jim is a jerk is out of bounds.

 

[jimfromnsf]

"I can see I am dealing with a <i>***Reference to Ad Hominem Deleted**</i> that is spreading misinformation,"<br /><br />You must be looking in a mirror<br />You are the one spreading the misinformation.<br /><br />MSL mass is not "changing" It changed months ago. <br />Again you do not know what you are talking about. Like I said, I am working on MSL. <br /><br />Explain why they chose not to use "5 - 134 ft diameter chutes" or any other combination? <br /><br />Get that <i>***User Name Distortion Deleted***</i>? <br /><br />Hear is the plain and simple statement, how cand ESA, NASA and the russians be wrong, <i>***User Name Distortion Deleted***</i> be right?<br /><br />Plain and simple chutes can not, repeat, CAN NOT, get a package to the martian surface for less weight than a retro system<br /><br />

 

[thereiwas]

Can we see some numbers, please?

 

[telfrow]

<font color="yellow">jimfromnsf</font>and <font color="yellow">137estreet</font><br /><br />I have edited the posts in this thread for ad hominems and user name distortions.<br /><br />Fair warning to both of you: <b>Do not</b> continue this type of behavior in this, or any other thread. <br /><br />Enough is enough. <div class="Discussion_UserSignature"> <strong><font color="#3366ff">Made weak by time and fate, but strong in will to strive, to seek, to find and not to yeild.</font> - <font color="#3366ff"><em>Tennyson</em></font></strong> </div>

 

[j05h]

<i>> You both must come from the same mother. </i><br /><br />No, because my brother would have gotten me a tour of the Shuttle cockpit! <img src="/images/icons/wink.gif" /><br /><br />70km/hr upward is going to be a serious feat for a winch that has just spent 6 months in deep space. And, again, you have to figure the mass of the cable. MSL is a big vehicle, something like 800kg. Steel cable, synthetic rope or kevlar strap, the SkyClimber's cable is going to mass quite a bit. How much does 1000' of 1/2" steel cable weigh?<br /><br />I still don't get the "SkyCrane" concept, either. A pallet or Viking-type rockets seems so much simpler. Drop the aeroshell, stabilize, wait, thrust, cut the engines at contact, drop engines/tanks after checkout. Cut the pallet out if possible. <br /><br />Josh<br /> <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[windnwar]

Although it may be a silly comparison look what happened to the several different cablessynthetic ropes on the recent mythbusters episode when they tried to use them to sling a car around a 90 degree turn at 35 mph. That car wieghed approximetly 3,000 pounds and at 35mph it snapped cable that had a break strength of close to 18,000 pounds. <br /><br />Compare that to your cable that will have to fight against a similar load at a higher speed. That will have to be one hell of a cable and it'll have to be extremely flexible to keep it from snagging at the speeds your going to run it through the winch. If you can build such a cable, please sell it to the space elevator guys. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <p> </p><p><font size="2" color="#0000ff">""Only two things are infinite, the universe and human stupidity, and I'm not sure about the former." --Albert Einstein"</font></p> </div>

 

[CalliArcale]

*mod hat on*<br /><br />This board is not a place to act like grade-schoolers. Do not attempt to continue the fight.<br /><br />*mod hat off* <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[telfrow]

I'd suggest you follow her advice and my direction.<br /><br />Discuss the topic of the thread and refrain from personal attacks. <div class="Discussion_UserSignature"> <strong><font color="#3366ff">Made weak by time and fate, but strong in will to strive, to seek, to find and not to yeild.</font> - <font color="#3366ff"><em>Tennyson</em></font></strong> </div>

 

[Boris_Badenov]

Stop arguing with them!!! I appreciate your posts & don't want to see you get banned. <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>

 

[brellis]

I agree with Boris. Your input is welcome. Take a deep breath, stay cool. <div class="Discussion_UserSignature"> <p><font size="2" color="#ff0000"><em><strong>I'm a recovering optimist - things could be better.</strong></em></font> </p> </div>

 

[jimfromnsf]

"Flame it up then run to mommy, a classic move. "<br /><br />I made no such move. You brought it on yourself.

 

[jimfromnsf]

"Sudden tangent forces acting on a body, a cable,"<br /><br />there is no such thing as tangent forces on a cable. The cables broke because of tensile forces

 

[spacehappy]

<font color="black">there is no such thing as tangent forces on a cable.<font color="white"><br /><br />Come on pal give him a break, the tangent force is the force acting along the tangent line to a circular motion, (sling a car around a 90 degree turn at 35 mph) and those who know what they are talking about tend to forget that they are talking to someone who doesn't know the subject matter. He explains everything to you in great detail and all you can come up with is one liner’s, some things are very obvious to those who know. Don’t bother posting a one liner on me I won't answer it. <br /></font></font>

 

[j05h]

SpaceHappy - Jim often answers in one-liners, it's his style. He'll give a longer answer if necessary.<br /><br />What do you think the mass of cable, reel and winch would be for an MSL-sized SkyClimber? What is the actual force applied to the cable, both dropping the payload and reeling it in? These are the real questions. I posted last night MSL will mass around 80kg/1760lb. How much for does that exert, climbing to 70mph? I don't care if it's tanget forces or not, what strength of cable is needed? That is something everyone has dodged on this thread. <br /><br />http://www.gbgindustries.com/StrandedCable.htm<br /><br />Has various steel cables. The absolute minimum is 1/8" lin at 1200lbs breaking strength (35lbs/1000') A more likely back-of-envelope item would be 3/8" 1x19 stainless or galvanized (Jim? help on that plz - will it react in space?) with a breaking strength around 18000lbs and massing 300lbs/1000ft. You might be able to get lighter metal cable using a titanium allow, but it's still going to be 100-200lbs of cable. Plus winch. Hundreds of pounds to climb that cable, that's a lot of retros and airbags. Pathfinder-type landers used short Kevlar straps to stand-off the backshell then airbags and retros for a reason. It Works. Viking/Phoenix landers also work, using aeroshell/retrosto land.<br /><br />YMMV, but SkyClimber seems to be a solution looking for a problem. If it works great on Earth, great, but it's not going to help on Mars. <br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[spacehappy]

<font color="black">80kg/1760lb. How much for does that exert, climbing to 70mph?<font color="white"><br /><br />Do you mean 800 kg and I thought they said 70 km/hr with a acceleration rate of 3.8 m/s not 70 mph, that’s a big difference. At 70 km/hr that is about 43.5 mph. <br /><br /><font color="black"> Has various steel cables. The absolute minimum is 1/8" lin at 1200lbs breaking strength (35lbs/1000') A more likely back-of-envelope item would be 3/8" 1x19 stainless or galvanized<font color="white"><br /><br />I would favor a belt made out of Spetra. There are a lot of different types of material available such as spetra - one commercial use that is in use today is for ultra high strength fishing line, very small diameter is needed for the same diameter test line compared to the rest.<br /><br /><font color="orange">Ultra high molecular weight polyethylene (UHMWPE), also known as high modulus polyethylene (HMPE) or high performance polyethylene (HPPE), is a thermoplastic. It has extremely long chains, with molecular weight numbering in the millions, usually between 2 and 6 million. The longer chain serves to transfer load more effectively to the polymer backbone by strengthening intermolecular interactions. This results in a very tough material, with the highest impact strength of any thermoplastic presently made. It is highly resistant to corrosive chemicals, with exception of oxidising acids. It has extremely low moisture absorption, very low coefficient of friction, is self lubricating and is highly resistant to abrasion (15 times more resistant to abrasion than carbon steel). Its coefficient of friction is significantly lower than that of nylon and acetal, and is comparable to teflon, but UHMWPE has better abrasion resistance than teflon. It is odorless, tasteless, and nontoxic.<br /><br />Its melting point is around 144 to 152 degrees Celsius, and according to DSM, it is not advisable to use UHMWPE fibers at temperatures exceeding 80 to 100°C for long periods of time. It bec</font></font></font></font></font>

 

[windnwar]

Most of the cable i've messed with personally has been used for antenna tower guy wires for radio and tv. Even 3/8 inch cable is very stiff and unwieldy to coil. The spool it is rolling up and down would have to be fairly large to keep it from being too tight of a bend radius. Beyond just the strength needed for the cable to survive, trying to reel in a cable like that at those speeds i'd think would be very difficult for the winch system to handle. High speed and high load, it'd need some serious reductiong gears and a very highspeed motor to get the rpms needed, all while not tangling. <br /><br /> <div class="Discussion_UserSignature"> <p> </p><p><font size="2" color="#0000ff">""Only two things are infinite, the universe and human stupidity, and I'm not sure about the former." --Albert Einstein"</font></p> </div>