Originally Posted by metlfreak
Hey guys I saw on here where someone was going to make an upscale Ram Jet. I have also thought about this. Looks like I can get everything from semroc. however im having a little trouble getting the fin patterns (both inside and outside) just wondering if anyone has them. Also isnt there a computer program that makes it really easy for upscaling and designing rockets?
Sorry for all the questions ive been out of the loop for about 4 years. im just getting back into the hobby again.
No computer program for upscaling just use a little basic math.
First figure out what size body tube you want to use.
Go to Jimz's site and download the plans.
On the finset the balsa sheet is 3" wide so use that as your reference. Print out the fin sheet.
Us a copy machine going up or down enlarging or reducing until the sheet shows that it is 3" wide.
Now to upscale
Divide the body tbe size you will be using for the main body, for example a BT-70
by the original body size which is a BT-55 1.325" O.D.
You get 2.217/1.325=1.6732 or in other words 167%.
Blow all the dimensions up by 167%. so the main body tube (there are 2 of them and they are 5.3" long each.
So 5.3 x 1.67=8.85" long each
Just continue on from there.
Just in case you don't know all of the body tube length are on the page on the plans with the caliper scale and compass.
OH, yea when you get the fin pattern right just hit 167% on the copy machine for your fins.