0
JohnRich

Freefall Time Slide Rule

Recommended Posts

Remember these? (See the attached image.)

This was before we had fancy electronic gizmos to tell us exactly how much freefall time we experienced on any given jump. Back then, we consulted tables of numbers, based upon exit altitude, opening altitude and type of skydive.

This little cardboard device featured here operated like a slide rule. You lined up the exit altitude on the top row, with the opening altitude on the sliding insert on the bottom row. Then in the two windows below, you had the calculated freefall time, depending upon the speed of the discipline in which you were engaging: either formation skydiving, or freestyle. (Head-down and sit-flying hadn't been invented yet either.)

In the example shown in the image, exit was at 13,000 feet, and opening was at 2,500 feet, giving 70 seconds of freefall time for formation skydiving.

Oh, and this was in the days of big jumpsuits too, so freefall speeds were a little slower then, than they are now.

There were handed out by Action Air Parachutes, which was the pro shop at Skydance Skydiving, in California.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

0