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JMR (Joint Multi-Role) & FVL (Future Vertical Lift) Programs


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Nov 24, 2008
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Handy chart showing the relationship between discloading and downwash velocity.
The V-22 sits around 22 lb/ft2 and is not *very* pleasant to stand beneath.
Tilt-wings are anywhere between 30-50 lbs/ft2, so it only gets worse.

It is interesting to note that the downwash hits the ground and then spreads radially horizontally, but the vertical distribution of the velocity is different in the case of higher vs lower discloading. With low discloadings, the flow has the highest speed some distance away from the ground, so it tends to overturn people. With high discloadings, the flow has higher speed, but it's concentrated at lower heights above the ground, hence with less overturning moment. Walking in that high speed flow has been described as akin to "wading in a shallow stream".
View attachment 642365
A practical example ;) ...
View: https://twitter.com/bundeswehrInfo/status/1344190233684758528?s=09

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