How Far Will A Pusher Plate Take You?

[Nightside]

12 hours ago, Spacescifi said:

 

Call me crazy but I say there IS a way to make an atmospheric launched Medusa using nukes or AM bombs.

Step 1: Make the large catcher net. It's going to be HUGE with tethers.

Step 2: Attach tethers. From the net to the sides of the spaceship.

Step 3: Attach an array of booster rockets to the edges of the net. A

Step 4: Launch the net via the boosters, while the net tugs at the ship which remains on the ground, while fully stretched, the grounded ship launches a a nuclear missile to detonate in an airburst  high above it where the net is hovering.

 

Before the nuclear missile is launched the booster rockets detach and fly away from the net.

Then before the net can fall back to Earth the nuke detonates, and in strange display, the ship on the ground is yanked upward as if by some massive balloon... propelled by NUCLEAR explosions.

 

We could do it... and my details and methods may be off, but this IS an engineering problem we CAN solve.

 

SS Mary Poppins

[magnemoe]

On 4/7/2020 at 3:55 PM, Bill Phil said:

Not because there isn't enough energy, but because the pusher plate is actually very inefficient. It's basically a brute force attempt to harness nuclear energy for propulsion. Making the plate larger to catch more propellant/energy and making the shocks more efficient would improve performance. Indeed a larger Orion ship (probably taking advantage of thermonuclear pulse units as well) could likely get much higher specific impulse than just 12 thousand seconds, but at that point making large vehicles becomes less practical and it's better to use something more like Mini-Mag Orion or Medusa for that performance.

 

This, the problem is that an nuclear bomb is hard to contain and small nuclear bombs are not weight effective, the smallest possible bomb is around 50 kg and is 0.1 kiloton while an 200 kt is say 200 kg. Multi megton bombs is above a ton, 20 MT is 10 ton I believe but this is an icbm warhead who is heavier so at large yields it become more linear. 
You can not contain 0.1 KT in an spaceship, that is 100 ton of tnt. However an ship using hundreds of kiloton pulses would have to be massive, think star destroyer. 
Medusa is interesting as it can spread out the pulse mush more letting an smaller ship use larger charges who is more efficient. 
Mini Mag is an fusion engine who is another type of engine, yes its pulsed and nuclear but its much weaker pulses, less one one kg blasts, this you can contain magnetic, one problem is power as it need to be external powered and you can only fire then you have enough charge. 

[Bill Phil]

3 minutes ago, magnemoe said:

Mini Mag is an fusion engine who is another type of engine, yes its pulsed and nuclear but its much weaker pulses, less one one kg blasts, this you can contain magnetic, one problem is power as it need to be external powered and you can only fire then you have enough charge. 

Mini Mag is fission - just like Orion. However instead of chemical explosives to compress the fissile core, it's done with a Z-pinch. Now the idea would be to get just enough power from each pulse to recharge the capacitors, and to have backup capacitors just in case. 

You can use some fusion fuel in the fissile core to increase the neutron flux and thus the fission rate to get a higher yield per shot. This should increase ISP as well.

I've been wondering if an "afterburner" is possible for Mini-Mag to increase thrust at the expense of specific impulse. Using the fusion boost, this could be a reasonable loss for more thrust for, say, fighting gravity during a lofted ascent.