KSR-420S Sounding Rocket This Korean sounding rocket was used to gather data on ozone concentration over the Korean peninsula. The KSR-420S also carried a highly-specialized device to measure micro gravity. In somewhat less peaceful times, the KSR-420S could be modified to carry a 200kg destructive payload over a considerable distance. This sport-scale model of the KSR-420S flies on a cluster of three 18mm model rocket motors As a skill level 2 kit, the KSR-420S is easy to build. This makes it a great choice for rocketeers new to clustering. $26.95  Dimensions Overall length : 27.475" Diameter : 1.637" (BT60) Fin Span : 6.21" Weight : 3.7oz Recommended Motors Estes® 3 x A8-3, 3 x B4-4, 3 x C6-5 Challenges This rocket is pretty easy to build. The balsa fins are pre-cut. Self-adhesive decals are cut from the included decal sheet. The red fin and nose cone are painted, all other markings/bands are decals. Parts A laser-cut centering ring with 3 holes is provided to prevent ejection gasses from blowing out the back.