I remember first encountering this problem on a kit from Quest. The situation was made worse because so little of the engine hook could be flexed when inserting the engine. Just trying to fit an engine would bend the engine hook far enough that it wouldn't spring back enough for the rear of the hook to engage the engine casing -- meaning you'd need to use a tape wrap over the engine hook and around the engine mount tube and the engine (making the engine hook somewhat pointless).
One place where the newer engine hook design could be problematic would be with the smaller diameter 13mm motors -- as the efflux from the motor could impinge on the extended hook -- causing a "thrust vectoring" effect.
Hi Naoto, A few years back, the 13mm engine hook design did cause thrust vectoring. Estes re-designed it in 2013. It now has a smaller finger tab that is out of the way of the motor thrust. https://modelrocketbuilding.blogspot.com/2013/08/new-mini-engine-hook-from-estes.html
Has anyone ever identified the person or persons responsible at Estes for the decision to solve the non-existent problem of engine hooks by adding the extra metal tang at the bottom of the hook? We somehow survived several decades without it.
Hi Anonymous, I don't know who the person was that came up with the extended engine hook finger tang. I believe the Estes Alpha was the first to use an engine hook in a kit. (1967) The engine hook on the far right side of the picture was the kind that could scratch your hand up if you tried to catch a rocket before it could touch down. That's why an additional rounded bend at the bottom was added later on.
I remember first encountering this problem on a kit from Quest. The situation was made worse because so little of the engine hook could be flexed when inserting the engine. Just trying to fit an engine would bend the engine hook far enough that it wouldn't spring back enough for the rear of the hook to engage the engine casing -- meaning you'd need to use a tape wrap over the engine hook and around the engine mount tube and the engine (making the engine hook somewhat pointless).
ReplyDeleteHi Naoto,
DeleteThe Quest and recent MPC labeled kits had the bendable engine hooks. I've had to use the tape wrap too!
One place where the newer engine hook design could be problematic would be with the smaller diameter 13mm motors -- as the efflux from the motor could impinge on the extended hook -- causing a "thrust vectoring" effect.
DeleteHi Naoto,
DeleteA few years back, the 13mm engine hook design did cause thrust vectoring. Estes re-designed it in 2013. It now has a smaller finger tab that is out of the way of the motor thrust. https://modelrocketbuilding.blogspot.com/2013/08/new-mini-engine-hook-from-estes.html
Has anyone ever identified the person or persons responsible at Estes for the decision to solve the non-existent problem of engine hooks by adding the extra metal tang at the bottom of the hook? We somehow survived several decades without it.
ReplyDeleteHi Anonymous,
DeleteI don't know who the person was that came up with the extended engine hook finger tang. I believe the Estes Alpha was the first to use an engine hook in a kit. (1967)
The engine hook on the far right side of the picture was the kind that could scratch your hand up if you tried to catch a rocket before it could touch down. That's why an additional rounded bend at the bottom was added later on.
A bendable motor hook is manufacturer malpractice, full stop.
ReplyDelete