Hi-max Ribs?

[ironnerd]

Just a quick reality check.
Are the ribs from a Hi-Max compatible with the LE?
I looked at my .pdf plans and they look the same (except for the lightening holes in the nose rib).

Note: I plan to take a hard look at my full-scale Hi-Max drawings when I get up to the airport this weekend to see what differences I spot.

[IflyHG]

That is a bit of a loaded question.  Do a search for airfoil and read some of the posts, there have been some good discussions.  This is what I can say from first hand knowledge.  I have a digital version of the MiniMax 1030F where it says on the rib drawing that it covers Model NOs 1100 - 1700, and I have a paper version of AirBike plans where the rib sheet looks identical to the MiniMax digital sheet.  In Leonard's introduction video he says the LEU wing is a MiniMax wing but that he modified the design to make the ailerons half span.  In the video, I don't recall him saying anything about changes to the airfoil.  I have LEU and LEXL plans and the rib pattern is the same between the two Eagles.

There are some notable differences in the plans.  One is the thickness of the spar webs.  The MM & AB wings use 1.5mm thick spar webs, the Eagles use 3mm thick spar webs, this impacts the spacing on the rib verticals that go on either side of the rear spar.  The area that supports the aileron cove is handled a little differently.  Whether or not to have a vertical support in the aileron, and what that support should be (1/4 x 1/4 with gussets or just a gusset, or no support).  The MM & AB ribs use 1.5mm thick gussets, the Eagles use 0.8mm thick gussets.  The shape and size of the gussets is different between the sets of plans.

So are ribs from a Hi-Max compatible with the LE?  A direct answer is no.  You can't take ribs built for a Hi-Max and use them to build wings using LE plans, there will be incompatibilities.  If you want to build a LE you are most likely to be successful if you build to just 1 set of plans. 

That isn't to say that you can't learn a lot by studying plans for related ultralights as well.  That is why I bought LEU, LEXL, AB, MM plans and the Iron Design supplementals.  Things that were not clear to me in one set of plans were clear in another.  I have also enjoyed comparing and contrasting how these 5 sets of plans solve the same problems in different ways.  It is also clear that the LEXL implements a number changes as compared to the LEU that in my opinion are improvements. 

Enjoy the process, this will be a journey.

[ironnerd]

My thinking was that I would use the Max drawing as a starting point for the LE rib, and make the adjustments for the different spar thickness (which is a good catch - thanks for pointing that out). From there I would build a rib jig.

I tried printing the rib from the plans and piecing it together, but it did not come out the right size.

[IflyHG]

I had the same experience with printing out the pages, as have others.  Here are some options for moving forward.  You could order the full size rib plan from Leonard.  This involves the least risk as everything else in the plans should mate.  Some people have had success with adjusting the print scaling to get them to come out to the right size.  You still have to fiddle with it as some sheets have gaps between them and not everything lines up perfectly.  Keeping the bottom edge straight and the verticals actually vertical is critical to success.  The vertical that mates to the front spar is easy to not have vertical and then the front spar isn't vertical in the wing (some builders have had this issue). 

Mixing drawings for different designs is fraught with peril so generally not recommended here but if you do go down that road...

I don't know if anyone has tried your approach with adjusting a MM drawing but if you are careful that could be made to work.  As you stated, the nose ribs will have to change to account for the different front spar thickness, the location of one of the verticals for the rear spar will need to change for the same reason.  If I were going that route I would transfer all the LE specific content to the MM drawing, and then build the rib jig from that.

You already have LEU plans but if you were willing to change to an LEXL (buy another set of plans) then you could purchase the Iron Design supplementals which has a full size rib drawing.  The Iron design supplementals are CAD generated and have differences from Leonard's plans so you shouldn't try to use information from the ID plans to build LEU wings.  If you go this route you build the ID wings and mate them to the LEXL.

It has been said many times here that 1 change begets 10 more by accident, and some you don't figure out until further into the build.

[ironnerd]

So... could an LE/XL/DE/CE use the fiberglass Mini-Max drooping wingtips?
I have no plan to do so, but it seems like someone would want the "finished look and a little extra lift" at the cost of $270 and 10# of additional weight.