EZ AHAB

I understand the purpose of pdf very well. I'm just saying it's not exactly intended to reproduce scale drawings like CAD is. Maybe it works fine anyway, I've never tested it. Also, I've never actually tried to get something printed at Kinkos that I needed to be dimensionally accurate so I can't speak to that. If I really needed quality full sized prints, I would try to find a place that does architectural drawings. I don't live in all that large a city and there's one here so I would assume they aren't that hard to find??? Anyway, I usually just print everything at home on my inkjet printer on legal sized paper and then paste the pages together. That way I have full control over the dimensional accuracy of my prints. If I properly calibrate my printer it works fine. 1 inch equals 1 inch. I also have an old HP pen plotter that does an excellent job too but will only print vector images, not pdf or bmp. I got it on ebay delivered for $30. As far as CAD losing accuracy between packages; again I only have one package that fulfills all my needs plus I always use dwg format, not dxf so I haven't had to deal with any of that. It just seems to me that it should work very well. Maybe I'm wrong. I do know that after I import images to CAD and get everything set up properly and then print them again, they line up perfectly with the originals.

Looks to me like the solution to all this dimensional accuracy stuff is to use a CAD format. Reproducing dimensional accuracy is what CAD is for, not PDF. Am I just stating the obvious or is there a good reason this hasn't been done. I've digitized portions of the plans myself but not all of them. I redesigned the lofting of the fuselage on my plane so I drew all new fuselage bulkheads anyway. It shouldn't be all that big of a deal to simply import the images into CAD and scale them appropriately. I've done this plenty of times to repoduce the hotwire templates. What I don't know is whether or not raster images are exported in dxf format for printing purposes. I'll investigate and see. Also of note on the subject of dimensional accuracy is the fact that I measured the Roncz canard templates on my original plans I got from RAF. There are 2 that are simply mirror images of each other. They should be exactly the same length, right? They were about 1/10" off which I consider to be very significant since the whole chord length on the template is only about 10". That's a 1% difference even when comparing two original drawings printed at the same time on the same piece of paper! This could give you up to 1/2" of error over the 43" length of the largest wing template.

Still waiting to hear back from Wicks and RAF.

What concerns me is not the density, it's whether or not this is an approved substitute foam. This isn't a matter of density variations between batches of foam, I'm afraid it simply isn't the same foam. According to the canard pushers, foam is never used to transmit primary or secondary loads so the lesser strength may not be a big issue. However, it also specifically says not to substitute materials with less strength. The smaller cell size might affect the peel strength but the only way to find out would be to test it. I emailed Wicks concerning this and received a reply yesterday as follows: "The F200 is the same foam, but it was changed long ago to 1.6 density, in place of 2.0 density. Aircraft Spruce sells the 1.6 also." As I mentioned in my eariler post, I ordered samples from both suppliers. The foam is very similar but does appear to be a bit different. I weighed and measured the stuff from A/C Spruce and it does seem to be 2 lb/ft^3, not 1.6. It also has slightly larger cells and the color is slightly darker than the stuff from Wicks. They didn't tell me anything about compressive strength but Wicks did give me an MSDS number with which I was able to track down exactly what it was on the Dow website. What I'm worried about is the possibility that the type of foam was changed due to the original Styrofoam FB being discontinued and the new stuff was deemed close enough and never tested. I’m afraid Wicks may have assumed it was “the same foam” as it says in the email above and that they may not have sought RAF’s or Nat’s approval for the substitution. It was easy enough to find the strength of the new foam but I had to do some digging to find the original material’s strength. When I did find it I was alarmed to see that the new stuff has less than 60% of the strength of the original. This is what made me start questioning whether or not it is an approved substitute at all. There are other factors such as fatigue strength and no telling what else that may play a part that would have been tested by RAF if they approved it. I’m waiting for replies from emails I sent to Wicks and to RAF concerning this issue. I’ll let you know how it turns out.

You should save approx 7 lbs for a pair of wings. This doesn't include canard or winglets so they may save you another couple of lbs or so. As you said though, this has nothing to do with weight savings. I'm going to thoroughly run this to ground before going with the 1.6# stuff. I would really like to use it but I'm going to have to be sure it's ok first. If I can't get a definitive answer, I'll suck it up and buy from A/C Spruce.

I've been doing some research on the foam used in the flying surfaces of both the Long-EZ and the Cozy. What I've found is that the original "2 lb/ft^3 Styrofoam FB" called for in the plans doesn't seem to be made any longer. A/C Spruce still sells what they call 2 lb/ft^3 Styrofoam FB so maybe they stocked up on it? Wicks sells "POLYSTYRENE Blue Large Cell expanded 1.6 lb. density". I called both suppliers and the lady I talked to at A/C Spruce had no knowledge beyond what was printed in their catalogue. She gave me a phone number to their distributer which led to a dead end. Wicks sells 1.6 lb/ft^3 pipe insulation. I ordered samples from both suppliers and they are indeed different. The foam from A/C Spruce is, in fact 2 lb/ft^3 and has a larger cell size than the stuff from Wicks. What concerns me is that the original Styrofoam FB had a compressive strength of 35 psi while 1.6 lb/ft^3 pipe insulation has only 20 psi. That's less then 60% of the strength. Also, there are warnings in the old canard pushers about using only the correct type of wing styrofoam called for in the plans. It specifically says not to use different types with less strength. There is also, by the way, a specific warning against using dock floatation foam which I have heard others say is the same stuff. I would just order the stuff from A/C Spruce and be done with it but A/C Spruce is really expensive. The price difference between suppliers for foam for 1 airplane is $260. Add to that the fact that I would have to pay for shipping from A/C Spruce while I could go pick up the other stuff in my truck and you get probably more like $500 in price difference. Do any of you have any further insight/information on this? Perhaps a Cozy builder could find out since it is still a supported design.