▁fast en ers ▁or ▁cord ▁and ▁loops ▁inside ▁the ▁compart ment . ▁Many ▁high - per formance ▁light ▁aircraft , ▁hel ic op ters ▁and ▁some ▁smaller ▁tur b op rop ▁aircraft ▁use ▁bl ad der ▁t anks . ▁ ▁T ip ▁t anks ▁Many ▁aircraft ▁designs ▁feature ▁fixed ▁tip ▁t anks ▁mounted ▁at ▁the ▁end ▁of ▁each ▁wing . ▁The ▁weight ▁of ▁the ▁t anks ▁and ▁fuel ▁counter act ▁wing ▁b ending ▁loads ▁during ▁man oe uv res ▁and ▁reduce ▁fat igue ▁on ▁the ▁sp ar ▁structure . ▁ ▁External ▁t anks ▁ ▁Con form al ▁fuel ▁tank ▁Con form al ▁fuel ▁t anks ▁( C FT s ) ▁or ▁" fast ▁pack s " ▁are ▁additional ▁fuel ▁t anks ▁fitted ▁closely ▁to ▁the ▁profile ▁of ▁an ▁aircraft ▁which ▁extend ▁either ▁the ▁range ▁or ▁end urance ▁of ▁the ▁aircraft , ▁with ▁a ▁reduced ▁aer od ynamic ▁penalty ▁compared ▁to ▁external ▁drop ▁t anks . ▁ ▁Drop ▁tank ▁Drop ▁t anks , ▁external ▁t anks , ▁wing ▁t anks , ▁p yl on ▁t anks ▁or ▁bel ly ▁t anks ▁are ▁all ▁terms ▁used ▁to ▁describe ▁auxili ary ▁extern ally ▁mounted ▁fuel ▁t anks . ▁Drop ▁t anks ▁are ▁generally ▁exp end able ▁and ▁often ▁j ett ison able . ▁External ▁t anks ▁are ▁common place ▁on ▁modern ▁military ▁aircraft ▁and ▁occasionally ▁found ▁in ▁civil ian ▁ones , ▁although ▁the ▁latter ▁are ▁less ▁likely ▁to ▁be ▁disc arded ▁except ▁in ▁the ▁event ▁of ▁emer gency . ▁ ▁Drop ▁t anks ▁were ▁originally ▁designed