# Hohmann Transfer Delta-V Approximator

Speaking of handy little Mathcad tools, this one is a generic delta-v approximator for planet-to-planet Hohmann transfers, based on the same mathematics as this Stack Overflow answer:

http://space.stackexchange.com/questions/1380/how-to-calculate-delta-v-required-for-a-planet-to-planet-hohmann-transfer

As mentioned there, it makes various assumptions, including that the bodies’ orbits around their sun are within delta of circular and coplanar (which works reasonably well for Sol), and that you aren’t using low-thrust drives and as such it can get away with treating burns as instantaneous. The further you wander away from these, the more approximate the approximation gets, belike. Caveat calculator!

Anyway, here it is:

https://onedrive.live.com/redir?resid=8B53BC30DA65DCAA!90356&authkey=!AAMfSsixhk7pGRI&ithint=file%2cmcdx

Enjoy!

# Basic Delta-V Worksheet

So, as those who follow my Google+ account will know, I use PTC Mathcad to do the various calculations behind the scenes to reality-check my work, starship designs, orbital parameters, etc., etc. And being the kind and generous soul that I am, I thought I might clean up and share my tools for the benefit of, well, everyone who wants to do this kind of thing.

Here, then, is the first of those cleaned-up sheets – a basic calculator that does the ground-to-orbit-or-escape delta-v calculation, as illustrated by Atomic Rockets here.

Here’s what it looks like (printed as XPS); and here’s the live version for those of you who have PTC Mathcad (requires only the free-for-life Express version).

# Reactionlessness

Have a not-my-fiction recommendation:

https://grantvillegazette.com/wp/article/bumped/

…momentum transfer at a distance: nice trick if you can do it. Just ask any ontotechnologist who’s trying to expand the reach of vector control. Although, Eldraeverse-wise, (spoiler) rira vs lbh pbhyq svther bhg ubj gb qb gung gevpx jvgu irpgbe pbageby, vgf hanibvqnoyr pbafreingvba-ynj pbzcyvnapr jbhyq zrna lbh jerpxrq fbzr cresrpgyl tbbq genvaf va gur cebprff.

# Atomic Rockets!

I just became a patron, via Patreon, of Winchell Chung’s Atomic Rockets web site.

And I am taking this moment now to tell you two things.

Firstly, whether you write SF – in which case I’m sure you already know about it and don’t need me to tell you – or whether you just read SF and want some insight into how things might work behind the scenes and/or exactly how hard the SF you’re reading is, and you haven’t visited it yet, go. Now. Stop reading this, and go read that. Then come back. (Well, first make sure you’ve got a few hours free. But then.)

Secondly, if you’ve enjoyed what you’ve been reading here, this is exactly the extremely valuable resource for, well, people like me that it’s intended to be. And the best part is, there’s lots of new material coming, time and funding to put which up is what this Patreon is intended to raise money for. That prospect certainly inspired me to contribute, but it wouldn’t hurt, gentle readers, if you were to go and do likewise.

(Not that I’d complain if you were overwhelmed by the urge to give me some money too, you understand. Just sayin’.)

After all, as the eldrae would put it themselves: “anything worth doing is worth doing for money; therefore, anything worth having is worth paying for”.