ETLB Squawk Forums — Archive

Hi,
In the past I have owned a 1600R. I am currently building a 1550V. I am getting ready to start on the wings. Not that it's hard to get in and out of the cockpit. But I'm thinking that the 1550V will be a little more tricky than the 1600R. Has anyone ever thought about modifying the top of the first wing rib bay to support the weight of the pilot. So maybe you could climb on the wing to get in and out of the aircraft.

Ken

I am actively currently thinking about that but I worry about crushing the spar since they are not solid and might not like it.  

If anyone has any ideas though I am about to have my wing torn down to the skeleton so I'd be very interested, haha..

A "wing walk" could be useful and would probably be reasonably doable given some thought and attention.

However I might add to your considerations that in the pat I had a "standard" minimax (1984 version in other words) and a V-Max.  I'm not sure how the 1600 you mentioned was configured but...

On the first max I would enter it using the "boarding step" in front of the wing in the fuselage and sort of step around the fixed windshield.
On the V Max the seat back is moved a few inches aft of where it is on the versions using a lighter engine.  The seat back rests right against the rear spar carry through bulkhead.  I found it quite easy to stand BEHIND the wing on the left side of plane and just step my right foot into the seat and grabbing/bracing the "headrest" of the turtledeck I could just step up in and lift my left foot over the aileron and in.  It was so easy I never used the boarding step I cut in front of the wing.  I also entered it with the engine running because I'd hand prop the VW and entering from the back was much safer, more moreover it was also much simpler.   I was 35 years old then and 170 lbs or so and am 5'11".  This method probably would not work for all people at all ages.....  Shorter legs would obviously increase the difficulty.

I have plans for the Ultra-Baby which uses the Mini-Max wing design.  The plans show wing walks, just 1/8 ply boxes with some internal reinforcements.

You're proposing to put maybe 200 lbs of shear on the root attachments. I suggest that each attachment should be able to take 200 lbs.  Note that flight loads impose only a few pounds of shear at the root even at the design limits.  If the birch plywood spar doubler takes 3350 psi in bearing perpendicular to the face ply grain then the bearing on the bolt hole is .252x3350=209 lbs. Likewise the spruce spar cap lends an additional 109 lbs of bearing for a 1.5 safety factor.  What about tear out? A similar computation using moduli of rupture indicates plenty of strength (>10x). Then turning our attention to the aluminum carry-through, can it take the bending imposed? I suggest that the mounting bolt should be nearer the end of the carry-through especially if the carry-through has been cut down for weight savings.

Good information Bob. I really haven't given it that much thought. The photo that Walkabout posted was exactly what I was thinking about doing. I just assumed that the structure of the airframe would handle the weight. I was planing on putting thin plywood on each side of the two ribs. And adding an extra nose rib. I guess maybe I should rethink this. I usually don't make modifications to the airframe without checking with Team.

It seems this paragraph from ANC-18 would preclude loading the root fitting bolts in shear without some modification:

the 1550V is actually easier than the 1600r because you can use the windshield bow for a handhold. Rather than have a wing walk, I always put my foot on the upper fuselage longeron before stepping down to the seat.

Chris