Originally Posted by rcjets_63

erbroens,

Yes, that particular incident is rather well known and and unfortunately led to the loss of a beautiful model. The incident involved two very large "subsonic" tanks being released from the wing pylons. My understanding is that one of the tanks got hung up and possibly hit the plane. Asymmetric drag would have made matters worse.

Dropping tanks or ordnance (from a model or a full scale aircraft) isn't as simple as may seem. The release mechanism must be reliable, the stores must drop away cleanly without the possibility of getting hung up or striking the plane. Full scale fighters (such as the F-16) include a pyrotechnic charge that fires to push the bomb/tank away and there are limits of the +ve/-ve "G" at which the stores may be released.

In my case, I built the smaller "supersonic" style tank and installed it on a centerline pylon below the plane. Since it is only a single tank on the centerline, I don't have to worry about asymetric drag should there be a release failure. Additionally, there is nothing on the underside of the fuselage on which the tank can get caught. The tank is installed at a slight negative angle to accomodate the AOA of the plane flying in level flight. The front of the pylon was designed to create a local region of high pressure at the top/front of the tank to push the tank downwards on release. The BVM EZ drop is a simple and reliable release mechanism which we have previously tested releasing 1-1/2 lb stores. The eyebolt into the tank is carefully adjusted such that the tank has minimal play on the pylon and there is little sideload on the release pin. There is an alignment guide at the rear of the tank to keep it straight on the pylon. The drop is controlled by a button valve tripped by the brake servo using a mix. The setup was tested/adjusted extensively on the ground and then flight tested this weekend to ensure it functioned perfectly before bringing the jet to a major show. Five drop tests were done. The last four were perfect; the first attempt was a failure as I'd forgotten to connect the airline (D-oh!) but this gave an opportunity to land the plane in a strong crosswind with the tank attached. As you can see by the first three photos, the landing went fine too.

Still, point taken and I don't expect to be dropping the tank all that often. Why go looking for trouble as scale jets are already complicated. Also dropping onto hard packed Arizona desert is a bit harder on the tank than dropping onto grass.

Regards,

Jim