Talk:Base Defence Systems

I added some info about TFTD to the article since it talks about TFTD too. I noticed though that some of the info conflicts with Base_Defense (TFTD) article. e.g. here it says the item limit has been raised to 110, there it says the limit is still 80. Anyhow, I can verify there's a sorting algorithm from my experience, but not much further. I wonder if it may end up preferring unresearched guns for example.. Cesium 20:02, 30 December 2009 (EST)

Hadn't realized that there was a page for TFTD. I just corrected it to 110 (this number is actually from the Unofficial Strategy Guide but from what I recall it is correct). About the sorting algorithm I can't confirm it. Hobbes 20:40, 30 December 2009 (EST)

I just ordered a lot of Jet Harpoons, Dart Guns and Chemical Flares to a base and let the aliens find it. The equipment available in the load screen was mainly Sonic Rifles and Sonic Cannons. The Darts, Jets and Flares were not available. Something has to account for the quartermaster being sane, and we do know some attention was given to base defense (since the item limit was raised). I guess only way to be sure is for someone to disassemble the executable and examine the code.... Cesium 09:35, 31 December 2009 (EST)

Well the quartermaster is mostly sane. However it does not check if you have researched the clip before it packs the shiny new Sonics. So be sure to move them out if you have not or you might end up with lots of guns without ammo. If you want Medikits be sure to reduce the number of spare weapons--Tauon 19:32, 16 October 2010 (EDT)

Not sure the 110 number for TFTD is technically correct. When I try to load more than 80 items on a craft I still get a warning. --Zombie 22:31, 30 December 2009 (EST)

The limit for weapons being carried in craft is still 80 but for the base defense missions the game allows for 110 items. Hobbes 22:56, 30 December 2009 (EST)

Penetration Math

"...Missile/Torpedo Defences are the most cost-effective of the defensive base facilities. The odds of penetrating 12 such modules and a Grav/Bombardment Shield are 30 to 1. On average, 30 attack ships will be destroyed before one gets through. Such a system costs $3.7 million. For the same price, 3 Fusion Ball/P.W.T. Defences with a Grav/Bombardment Shield will offer only 9 to 1 protection..."

Huh? Where is this math coming from? From the way I understand it, it's a simple binomial distribution (at least for exclusively one type of base defense module).

In order to bring down a battleship (3200 hits) you need to connect 7 rounds from a missile defense (500 damage). With 12 missile defenses and a grav shield, you have 24 bernoulli trials with a 50% probability of success. The probability of 6 successes or fewer out of 24 trials at 50% I believe is ~0.01133, or 1 out of about 88 ships getting through your defenses. I calculated this in excel via =BINOM.DIST(6,24,0.5,TRUE) so I am confident it is correct.

In the fusion ball case, I believe it is 2 or fewer successes out of 6 trials with 80% probability, =BINOM.DIST(2,6,0.8,TRUE), 0.01696, or 1 out of about 59 ships getting through.

While the original point still stands with my math (missile is more cost effective than fusion), the odds of penetrating either setup are greatly reduced, as is the difference between the performance of the two. Perhaps I do not properly understand the mechanics of base defense modules, or screwed up my thinking or math somewhere along the way.

--Jewcifer 12:57, 16 March 2012 (EDT)