Peter Mugridge
Veteran Member
I think it's more a combination of the vertical sides and the length. Probably not having any opening windows along the length helps as well. Consider this:
Mk 1 / Mk 2 pressure vented - vertical sides, 60ft length, opening windows throughout. No slam effect.
Mk 2 aircon - vertical sides, 60ft length, no opening windows. No slam effect that I remember.
Mk 3 - vertical sides, 75ft length, no opening windows. Slam effect.
Mk 4 - sloped sides, 75ft length, no opening windows. No slam effect.
Mk 1 / Mk 2 pressure vented - vertical sides, 60ft length, opening windows throughout. No slam effect.
Mk 2 aircon - vertical sides, 60ft length, no opening windows. No slam effect that I remember.
Mk 3 - vertical sides, 75ft length, no opening windows. Slam effect.
Mk 4 - sloped sides, 75ft length, no opening windows. No slam effect.