I was getting ready to start on the IV-P baggage area- my kit doesn't have the "elephant butt" wheel housings so I received two sheets of 1/4" material and no instructions. Thankfully I have a number of photos from different sources.

 The sheets, P/N 1026A  and 1026B vary in the fabric orientation- A is 0-90 and B is +/-45 degrees. I asked the factory and was told to use the 0-90 for the baggage area, but the photos of various projects show everyone using the +/-45 material. Could those who have gone before confirm what they've used and where?

  Also, I checked the archives and found some discussion about moving the hydraulic power pack forward to the area behind the pressure bulkhead. Is that a good location in terms of W&B?

Bill,

I had always planned to install an air conditioner in my IV-P and therefore expected to have an aft CG issue because of the A/C components installed pretty far aft. I moved my hydraulic pump forward to the right side of the baggage compartment, just behind the pressure bulkhead. I also machined 1” thick aluminum “spool” spacers to bolt between the engine mount and the fuselage, moving the engine 1” forward. Both mods have worked well in 700+ flight hours to date. If you do the engine relocation thing, you have to plan this early, as it affects the cowl fit, nose gear retraction, etc, etc. In the end, I can load my airplane to about 3600 pounds with four people and all stowables as  far forward as is “reasonable” before I run out of aft CG. That’s how I determined the max certification weight. I suspect there is some safety margin built into the published aft CG limit based on my flight testing to the aft CG/weight limit I certified, but even though I work with the Navy on operational test of their new airplanes for a living, I didn’t want to get into the area of expanding the CG envelope….I am too old for that stuff…and my wife is pretty sure this is the only Lancair I’ll ever own… J

To your specific questions: I used the +/- 45 degree honeycomb material for my wheelwell closeout and baggage area. The wheelwell closeout area is not subject to substantial twisting loads, so either sheet of material should work fine there. Consider the 45 degree material for the flat parts of the baggage closeout…especially if you extend  it all the way back to bulkhead 171. This will stiffen the fuselage just a bit in twist, but even so, the difference is very small, and either would work in my opinion. I did make cardboard templates for all of these pieces and fitted them carefully before starting to cut the honeycomb…mistakes with this material are expensive. I also trimmed the top off the bulkhead behind the main gear area to lower the “floor” of the baggage compartment as much as possible.  You can only lower it an inch or so and still have the wheels retract and the doors close under them. If you don’t have the gear and doors fitted and working, do this first, then extend the MLG bumper blocks to stop the MLG wheel retraction as close to the gear doors as possible, then make the top of the wheel the “floor” of your baggage compartment. Should get at least an extra  inch…which is significant in that teensy (according to my wife) baggage compartment…

Hope this helps!

Bob