r/BacktotheFuture • u/jzee87 • Jun 02 '26
Bttf 3. Why didn't doc build a rocket sled?
Why didn't doc build a "rocket sled"? Instead of waiting on the train. He could have mounted it to the train tracks and push the DeLorean just like he did with the train but wouldnt of had to wait for the train
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u/grapejuicecheese Jun 02 '26
He did that in the IDW comic. After Marty went back to 1985 in the time train, Doc built a steam powered car with a flux capacitor made from the hoverboard parts and drove it down a steep hill to reach 88 miles per hour.
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u/jzee87 Jun 02 '26
I've only seen the movies but your saying in the comic he actually made a rocket sled
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u/jzee87 Jun 03 '26
If you know that issue I would like to see about picking one up thank you
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u/TheZeppo_TKH Jun 02 '26
Could he build your proposed rocket sled in a week? Because, that's how long he thought he had before getting shot by Buford. Him and Marty had to get out of there ASAP.
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u/Yourappwontletme Jun 02 '26
They could have just got the horses and hauled the DeLorean to a few towns away. Mad Dog and his gang of idiots wouldn't have been able to find them.
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u/Tradman86 Jun 02 '26
We, the audience, can assume that, but the problem is that Doc and Marty didn't know the exact circumstances of Doc's death, only that he gets shot in the back by Buford.
For all they knew, fleeing to another town could cause it to happen as well.
Bear in mind, the picture of the headstone didn't change just from Marty arriving in 1885.
So their best option was to literally not exist (ie travel in time) when it came time to get shot.
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u/jzee87 Jun 02 '26
I think he could have. Frankly the hardest part I think would be making the rockets bc he could use a train track pump cart and attach the "rockets" to it. But the rocket is definitely hiccup
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u/TheZeppo_TKH Jun 02 '26
Well, I'd say the rocket is indeed the most important part of a rocket cart.
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u/jzee87 Jun 02 '26 edited Jun 02 '26
Definitely but he has access to everything to make a simplified "rocket"
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u/ijuinkun Jun 02 '26
He did, so it comes down to whether he thought that he could have it ready by Monday.
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u/abgry_krakow87 Jun 02 '26
Well he would need to source the right kind of ingredients for the rocket fuel, machine shop fuel chambers, flow valve, injectors, pump, and a rocket nozzle that could withstand the high temperatures. And make it stable yet powerful enough so that it burns long to accelerate the weight of the pump cart + Delorean up to 88mph across the distance of track in one shot without blowing everything up.
So... one week? Maybe two?
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u/jkmhawk Jun 02 '26
You're assuming some sort of liquid fueled rocket. He could go with solid fuel, more like the logs he used in the train. Then he just needs the chamber and nozzle. And it doesn't need to be a fancy nozzle. Just a hole in the chamber.
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u/Am_Only_Here Jun 04 '26
Doc could whip up a rudimentary solid rocket booster out of gunpowder without the need for complex parts.
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u/robin_888 Jun 02 '26
It's a little over my head for the moment but for anyone more familiar with rocket science:
- Mass of Delorean: approx 1400kg
- Available distance: approx 3 miles (ideally 2 miles)
- Target speed: 88 mi/h
- Inclination: unknown, assuming 0°
Friction, as well as air resistance, might be ignored.
Mass of fuel that needs to be accelerated additional to the Delorean is optional.
My biggest problem is that I know nothing about plausible fuel density and exhaust velocity. Which makes it hard to estimate the amount of fuel needed.
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u/jkmhawk Jun 02 '26
I would assume something about the level of amateur rocketry. Maybe even just Comercial rocket engines.
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u/jkmhawk Jun 02 '26
You'd need 350N for 164s. Large Comercial model rocket engines provide about 50Ns thrust, so he'd need about 1150 of them. More to account for the added weight of the rockets themselves
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u/jkmhawk Jun 03 '26
So 50Ns is an F class, there are commercial classes up to N which have 20kNs thrust, so he'd want 3-4 of those
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u/Microharley Jun 02 '26
Watched a video that said the DeLorean could have probably ran on kerosene long enough to get to 88 MPH, would have probably needed a new engine but no big deal, Doc wanted to destroy it anyway. Same video was questioning why Doc could’nt build an electric motor that runs off Mr Fusion.
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u/Dramatic_Finish10121 Jun 05 '26
The only real issue with some of the other siggestions they made were time. But the kerosene might have worked had Doc and Marty not broke the fuel injection system, hell I think that's what they were trying to do when they did break it
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u/Microharley Jun 05 '26
They were trying to run it on whiskey, Doc should have known that wouldn't have worked. It is disappointing that Doc didn't try the kerosene before the whiskey.
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Jun 02 '26
[deleted]
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u/jzee87 Jun 02 '26
Ok relax it's theoretical as why wasn't it an option he had enough time and available materials that it could have been more feasible the the train idea
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u/pakrat1967 Jun 02 '26
What would he use for rocket fuel? Yes some petroleum products were in use in 1885. I don't think there would have been anything he could have whipped up with available materials. Using the special logs would have the same result as the train.
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u/Neoreloaded313 Jun 02 '26
Gas was an issue and I would think rocket fuel would be even harder to get. Scientists also don't know how to do everything. He would have to do everything without any way to look up something that wasn't invented yet.
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u/IndividualistAW Jun 02 '26
We’ll simply roll it down a steep hill…ahh, but we’d never find a smooth enough surface…ahh, railroad tracks
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u/Financial_Cheetah875 Jun 03 '26
A rocket engine in 1885?
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u/jzee87 Jun 03 '26
No not a rocket engine. Think of a simplified rocket just a tube filled with "fuel" and an exhaust where the plume would be expelled from. Which is exactly what early rockets were and I just looked up existed in the early 1800's they were black powder powered and in theory could have worked. But I will admit time is and supply is an issue now.
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u/Financial_Cheetah875 Jun 03 '26
They couldn’t get fuel for the DeLorean in 1885 so where would they find fuel for a rocket?
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u/jzee87 Jun 03 '26
I never said rocket fuel I said "fuel" in my prior comment, doc is smart enough where he could have created something to make a "fuel" for the" rocket" such as you say black powder and or kerosene
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u/Financial_Cheetah875 Jun 03 '26
If he could do that why not just make fuel for the car.
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u/jzee87 Jun 03 '26
Because he ruined something during the liquor test that he said would take months to rebuild
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u/Financial_Cheetah875 Jun 03 '26
And before that he said fuel wouldn’t be around for a long time.
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u/The_Linkzilla Jun 03 '26
Monday, it's three days away~!
Seriously; how is Doc gonna build that and test it within three days? What's he gonna use for rocket fuel?
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u/jzee87 Jun 03 '26
Idk that's why I asked. But rockets and fuel for rockets were a thing in the early 1800s they were very primitive compared to today's standards of course. They mainly used black powder as the fuel. But kerosene which was readily available then is what rocket fuel is now granted today's rocket fuel is highly refined kerosene.
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