# Back to the Future III: An (semi)obvious solution... **URL:** \ **Category:** Cafe Society\ **Created:** [December 13, 2011, 1:27pm UTC](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029 "2011-12-13T13:27:39Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Mollie\_Magill](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mollie_magill/32/20882_2.png) [@Mollie\_Magill](https://boards.straightdope.com/u/Mollie_Magill)\ **Post date:** [December 13, 2011, 5:29pm UTC](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029/21 "2011-12-13T17:29:27Z")
Mea culpa: Looking it up, I see I mis-remembered. [The terminal velocity of a VW bug in free fall is 125MPH.](http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CCUQtwIwAQ&url=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DIyrvfhOI3ls&ei=U4rnToaoF8Te0QG2-KDpCQ&usg=AFQjCNGzDrfeyHU75rjsxKu9cr_L5S4FoA) At any rate, I stand by my assertion that you would not be able to coast this particular Delorean up to 88mph. ---
**Author:** ![Mollie\_Magill](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mollie_magill/32/20882_2.png) [@Mollie\_Magill](https://boards.straightdope.com/u/Mollie_Magill)\ **Post date:** [December 13, 2011, 5:34pm UTC](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029/22 "2011-12-13T17:34:28Z")
> [@PSXer](#): > > When lightnight struck the delorean it caused it to spin at 88 miles per hour. It leaves behind in the air flaming 99s as a result of the spinning. > > I never thought about whether the speedometer needed to indicate 88 or if the car just needed to be going 88 in some capacity I have a hard time accepting that the lightning made the Delorean accelerate to 88mph in that short space. Doc would have been killed by the g-force. (On a related note: What does it say about me that I have no problem with a fusion powered, time-traveling Delorean that flies, but I cannot accept that it can accelerate to 88 mph in under a second?) ---
**Author:** ![mlees](https://avatars.discourse-cdn.com/v4/letter/m/ba8739/32.png) [@mlees](https://boards.straightdope.com/u/mlees)\ **Post date:** [December 13, 2011, 5:40pm UTC](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029/23 "2011-12-13T17:40:41Z")
Dropping it off a hill (or rolling it down a hill) presents the problem of when it gets back to 1985, it’s going to be still rolling down that same hill. Into someones backyard, no doubt. Firing it on an airborne ballistic course via a Doc-Brown-rocket means the Delorean becomes a lawn dart in 1985. He needed a smooth surface (so they can actually reach 88mph), which would still likely be clear in 1985. I can’t believe Doc tried to use a stagecoach horse team. Was he drunk, or trying to make a point to Marty? ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [December 13, 2011, 5:46pm UTC](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029/24 "2011-12-13T17:46:57Z")
> [@mlees](#): > > I can’t believe Doc tried to use a stagecoach horse team. Was he drunk, or trying to make a point to Marty? We’ve seen how well he holds his liquor. ---
**Author:** ![constanze](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@constanze](https://boards.straightdope.com/u/constanze)\ **Post date:** [December 13, 2011, 5:52pm UTC](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029/25 "2011-12-13T17:52:30Z")
> [@mlees](#): > > I can’t believe Doc tried to use a stagecoach horse team. Was he drunk, or trying to make a point to Marty? He’s a scientist, he tests things. And how likely would be it that a physicist from the 1950s would know the top speed of a stagecoach of the top of his head (no reference books in the past)? Testing it, esp. if more horses = more power = more speed would work, doesn’t take that long. ---
**Author:** ![mlees](https://avatars.discourse-cdn.com/v4/letter/m/ba8739/32.png) [@mlees](https://boards.straightdope.com/u/mlees)\ **Post date:** [December 13, 2011, 5:53pm UTC](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029/26 "2011-12-13T17:53:27Z")
> [@constanze](#): > > He’s a scientist, he tests things. And how likely would be it that a physicist from the 1950s would know the top speed of a stagecoach of the top of his head (no reference books in the past)? > > Testing it, esp. if more horses = more power = more speed would work, doesn’t take that long. 😕 Even the fastest land mammal, the Cheetah, can’t do 88… ---
**Author:** ![constanze](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@constanze](https://boards.straightdope.com/u/constanze)\ **Post date:** [December 13, 2011, 5:54pm UTC](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029/27 "2011-12-13T17:54:09Z")
> [@One\_And\_Only\_Wanderers](#): > > Was the 88 mph just an arbitrary trigger then? I formed the understanding that the speed was necessary to enable the time travel at all, though I do not know where I got this from. They never fully explained it (because that would be difficult), it’s just stated that the flux capacitor needs the 1.2 Gigawatt and the car itself needs to be travelling 88 mph. Presumably because it’s a nice number/ cosmic constant. ---
**Author:** ![constanze](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@constanze](https://boards.straightdope.com/u/constanze)\ **Post date:** [December 13, 2011, 5:57pm UTC](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029/28 "2011-12-13T17:57:30Z")
> [@mlees](#): > > 😕 Even the fastest land mammal, the Cheetah, can’t do 88… But Doc’s not a biologist. How would he know that? ---
**Author:** ![mlees](https://avatars.discourse-cdn.com/v4/letter/m/ba8739/32.png) [@mlees](https://boards.straightdope.com/u/mlees)\ **Post date:** [December 13, 2011, 6:01pm UTC](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029/29 "2011-12-13T18:01:16Z")
> [@constanze](#): > > But Doc’s not a biologist. How would he know that? I am not a biologist either, and I know that. The scene was amusing on screen, but really, now. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [December 13, 2011, 6:11pm UTC](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029/30 "2011-12-13T18:11:27Z")
> [@mlees](#): > > The scene was amusing on screen, but really, now. I imagine that was the only reason for it. ---
**Author:** ![sitchensis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sitchensis/32/4892_2.png) [@sitchensis](https://boards.straightdope.com/u/sitchensis)\ **Post date:** [December 13, 2011, 6:46pm UTC](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029/31 "2011-12-13T18:46:48Z")
They could have hijacked a bunch of heavy duty pulleys and wire rope from the local mine and pulled the DeLorean in the opposite direction of a train going 22 miles per hour with four times the mechanical advantage. ---
**Author:** ![Skammer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/skammer/32/143_2.png) [@Skammer](https://boards.straightdope.com/u/Skammer)\ **Post date:** [December 13, 2011, 6:47pm UTC](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029/32 "2011-12-13T18:47:14Z")
> [@mlees](#): > > 😕 Even the fastest land mammal, the Cheetah, can’t do 88… But what if you harnessed _multiple_ cheetahs, eh, smarty pants? ---
**Author:** ![simster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/simster/32/1047_2.png) [@simster](https://boards.straightdope.com/u/simster)\ **Post date:** [December 13, 2011, 6:51pm UTC](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029/33 "2011-12-13T18:51:22Z")
> [@Mollie\_Magill](#): > > Are you starting from a standstill? don’t you always start from a standstill? ---
**Author:** ![Jas09](https://avatars.discourse-cdn.com/v4/letter/j/d07c76/32.png) [@Jas09](https://boards.straightdope.com/u/Jas09)\ **Post date:** [December 13, 2011, 7:06pm UTC](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029/34 "2011-12-13T19:06:16Z")
> [@sitchensis](#): > > They could have hijacked a bunch of heavy duty pulleys and wire rope from the local mine and pulled the DeLorean in the opposite direction of a train going 22 miles per hour with four times the mechanical advantage. Using mechanical advantage seems like a useful approach. What about using the train tracks but attaching a pulley system with heavy weights dropped over the edge of the ravine to “pull” the DeLorean up to speed? ---
**Author:** ![Balance](https://avatars.discourse-cdn.com/v4/letter/b/ccd318/32.png) [@Balance](https://boards.straightdope.com/u/Balance)\ **Post date:** [December 13, 2011, 7:15pm UTC](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029/35 "2011-12-13T19:15:06Z")
> [@cmyk](#): > > However… if all that was needed was 88 mph of inertial acceleration… why not just use gravity? Horse-draw the thing up a long, steep hill, grease the tires, and let the damn thing roll with reckless abandon until it hits 88. Doc: “I know, I know. Okay, we’ll simply roll it down a steep hill… no, we’d never find a smooth enough surface.” So, he considered it and concluded that it wouldn’t work. The problem he saw was not lack of hills, it was the lack of paved roads leading down those hills. > [@](#): > > If the friction is still prohibitive. If the Doc had time to create 3 chemically treated bundles of fuel, then certainly he could’ve rigged the driver’s gullwing door to fly open and devise an ejector seat + parachute for Marty, and just push it over the tracks right into the Eastwood Ravine. Still dangerous, but much simpler and less guess work / less things to go wrong. Besides, he has the hoverboard for a nice, soft landing. 1. He already had the fuel; he had been using it in his blacksmithing work when he needed a really hot fire. 2. The plan was for both Marty _and_ Doc to return to the future. He would need to arrange a safe landing for both of them–and a safe landing for either of them would be a very dubious proposition, given that they’d have to eject late and in the aftermath of a time jump. Also, the landing zone would be a twisted mass of ex-DeLorean. 3. The drop probably wasn’t long enough. If my math is right, you would need about a 265-foot drop, at minimum, to get up to speed. It’s hard to judge the available drop, but my guess, based on the scale of various objects in the scene, is that it’s around 300 feet. That might possibly be enough to get up to critical velocity, though it would give them only a fraction of a second to eject and slow their fall after displacement (which would be just as fatal as hitting the ground in the car, I imagine). Only a small part of that drop is available if they just roll the DeLorean off the end of the bridge, however. They only get a little more than the height of the trestle that way before they hit the slope–maybe 60 feet. To take advantage of the full drop, they’d need to be going fast enough to launch out over the middle of the ravine…which means they’d need to be going nearly 88 on the approach, anyway. They’d still need the train, the special fuel, and everything to make it work. (On the plus side, since they’d be going near the critical velocity, they wouldn’t have to fall very far to push them over.) Adding untested ejector seats and parachutes to that (in addition to being impractical given their time constraints) simplifies nothing while adding near suicidal risks. I fail to see how this is a better plan. > [@](#): > > I’m sure the Doc would be able to assemble a simple rocket assembly using a crude black-powder booster – or shoot, maybe even an H2O2 engine – with his chemistry know-how – then just let it do its thing and re-enter 1985. This is a slightly better idea, but… Marty: “Doc, you’re gonna get shot on Monday!” ---
**Author:** ![PSXer](https://avatars.discourse-cdn.com/v4/letter/p/48db29/32.png) [@PSXer](https://boards.straightdope.com/u/PSXer)\ **Post date:** [December 13, 2011, 10:30pm UTC](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029/36 "2011-12-13T22:30:02Z")
on the DVD commentary they say that it should have been obvious to Doc that horses pulling the Delorean would never get enough speed, but they included it anyway because it was a cool shot ---
**Author:** ![mlees](https://avatars.discourse-cdn.com/v4/letter/m/ba8739/32.png) [@mlees](https://boards.straightdope.com/u/mlees)\ **Post date:** [December 13, 2011, 10:45pm UTC](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029/37 "2011-12-13T22:45:50Z")
> [@Skammer](#): > > But what if you harnessed _multiple_ cheetahs, eh, smarty pants? The only way they would go 88 mph harnessed together is if I fired them out of a cannon first! 😛 ---
**Author:** ![davidm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidm/32/225_2.png) [@davidm](https://boards.straightdope.com/u/davidm)\ **Post date:** [December 13, 2011, 10:57pm UTC](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029/38 "2011-12-13T22:57:29Z")
> [@Mdcastleman](#): > > One thing that always bothered me about the railroad track idea: wouldn’t the tracks have shifted over a hundred years. Even a coulple of inches you have a spectacular derailment when the Delorean hits 1985. The entire Earth would have shifted over a hundred years. Heck, the entire solar system would have shifted over a hundred years. That assumes, of course, a privileged frame of reference but without that, how does a time machine find a spatial target (as opposed to a temporal target) anyway? ---
**Author:** ![alphaboi867](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alphaboi867/32/3898_2.png) [@alphaboi867](https://boards.straightdope.com/u/alphaboi867)\ **Post date:** [December 14, 2011, 12:11am UTC](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029/39 "2011-12-14T00:11:44Z")
> [@davidm](#): > > …Of course, that doesn’t explain what happened at the end of the second movie, where the car was just hanging in the air and got hit by lightning. I think Doc even came out and said that the Delorean was spinning at 88mph on it’s axis. > [@Mdcastleman](#): > > One thing that always bothered me about the railroad track idea: wouldn’t the tracks have shifted over a hundred years. Even a coulple of inches you have a spectacular derailment when the Delorean hits 1985. > [@davidm](#): > > The entire Earth would have shifted over a hundred years. Heck, the entire solar system would have shifted over a hundred years. That assumes, of course, a privileged frame of reference but without that, how does a time machine find a spatial target (as opposed to a temporal target) anyway? Yeah, just assume that the Delorean only stays in the same position in space relative to the Earth’s core. They never traveled far enought back in time for there to be any major geological changes to deal with. By the time of the cartoon Doc Brown had apparently improved on both time machines enough that they could travel in space as well as time. Now that I think about it how did Doc, who put so much effort into knowing the terrian and what obstacles could be in the Delorean’s way, manage to safely travel into the future? :dubious: He had no way of knowing what he’d risk running into in 30 yrs time. Naturally after the hover conversion this would be much less of a problem, but he didn’t get that until after he’d arrived in 2015. ---
**Author:** ![TBG](https://avatars.discourse-cdn.com/v4/letter/t/c89c15/32.png) [@TBG](https://boards.straightdope.com/u/TBG)\ **Post date:** [December 14, 2011, 1:12am UTC](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029/40 "2011-12-14T01:12:30Z")
The whole thing could’ve been avoided if he’d just saved the gas from his Delorean before burying it. [Previous page](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029.md?page=1) [Next page](https://boards.straightdope.com/t/back-to-the-future-iii-an-semi-obvious-solution/606029.md?page=3)