Intro: A Revolving Map-board for Open-cockpit Flying
I fly a microlight and I have a retracting undercarriage, the controls for which are between my legs. Consequently, I don't have room to have a mapboard across my entire lap, as other flexwing microlighters do. So I wanted a means to carry a map on one leg. That presents a problem, because navigating with a quarter mil map requires quite a wide expanse of map for a single flight.
So I experimented with various folding (and unfolding systems), which would be practicable for open-air flying. Then it came to me: what if I had the map wrapped around my leg and could revolve it.
I went to my local hardware store looking for something I could cannibalise and make a large, leg-sized tube out of. I was going to get a bucket, then my girlfriend suggested a flower pot! Perfect.
Step 1: Bill and Ben, the Flowerpot Men
Anyone who is around my age (46) and grew up in the UK will get this reference. Obalob was the noise Bill and Ben (marionette puppets made of flowerpots - in a TV programme for children) made.
Consequently, I call my method of aerial navigation the Obalob Method.
Take one flowerpot. . . .
Step 2: Check Size
It needs to be large enough to put your upper leg through.
You will need to remove the base to know it fits for sure, but in the shop you can estimate
Step 3: Remove Base
Step 4: Open Out
cut the pot from top to bottom ....then remove any strengtheners which will cause friction inside the tube.
I colour copied 2 x A4 views from my 1/4mil chart of England South, stuck them together (reduced the length to 1 1/2) and laminated them (interleafing two A4 pouches carefully to make a longer one).
To test the system out, I mounted the laminated chart around the pot with duck tape and then tightened the pot around my suited leg, securing it with a final bit of tape.
Because the flowerpot is conical rather than cylindrical, the map arcs.
For the final version, I used velcro to secure the map.
Step 6: Securing
Put velcro inside the tube to secure it around the leg. Do so, as I have, with the furry surface (not the coarse stuff) innermost, next to the pilot's leg. This is less for comfort, than to reduce friction when you try to rotate the map-board.
Step 7: Airfield Info, Radio Frequencies Etc
As I say, because the tube is conical, the map arcs around the map-board, so that it is not practical to have the map wrapped all the way around the flowerpot. I found that with a map of 45 nautical miles around my leg, I still had room for a second map of about 35nm. But as I fly around a sector rather than continuously in one direction, I think I shall use the additional available space for airfield information, checklists, radio frequencies, etc.
I have designed a Mk2 (about which, more later) which has a stack of available maps stored in the pot, (wrapped around the leg), which would allow for several hundred miles of straight-line flying.
Step 8: Go Flying
Get suited up, strap the map-board around your leg, securing it with velcro. Secure the map to the mapboard with velcro. Secure any addidional, laminated notes etc to the remaining space.
Rotate the map-board around your leg as needed.