Jim's XL build D-25

[Rich Snyder]

As always, guys; sage advice. I believe I will avoid trying to ream out any tubing and just buy a little bit of .058 wall thickness stuff. No use in forcing a fit when an easy fit is available. I like easy. The decision to bend the upper longeron is a tougher choice. As this is my first welding project I have been doing my homework and dutifully welding up scrap tubing for practice. The tech advisor from my EAA group is coming over this Saturday to school me and to see if what I'm doing is adequate work. Even then; a newbe like me likes to visualize himself hanging from solid tubing, not a weld. I get that the weld and patch is more proper. In my mind's eye I see the bend in the tubing bending more under stress but sees the weld breaking apart. I should have more faith in myself I guess. My welds have held under the most severe hammer beatings and when cut apart are not cold welds. Rich.

[rockiedog2]

hi Rich
of course do what you want to about the tailpost but here are a couple more considerations...
Leonard to my knowledge hasn't undersized any fuse tubing and calls out 035 for that tailpost. from that and field experience that is all that is necessary. anything thicker is overkill and needless weight. 
and when you go to fit up your vert stab to the tailpost and the front tube mount that it goes into you may wish you had a little slop in the tailpost. after finish welding the 2 tackwelded mounts may get a little misaligned and if you go .058 on the tailpost and it gets misaligned you're likely gonna have to heat and bend that front mount into alignment due you got no slop to play with cause your rear mount is a near perfect fit. now heating and bending that front mount into alignment is no big deal(hopefully you won't have to cut it off and reposition it but that is a possibility) but why do that to yourself just to add some needless weight?
generally speaking...Leonard has everything properly sized to my knowledge. i can't figure out why we would want to upsize anything unless it's the horsepower. we got precious little of that left over for climb and if we go arbitrarily adding weight here and there we got even less
well that's my idea of it.
but i think everybody oughta do their own thing.

[rfeenstra]

43.13 has a good section on tube structure repair approved methods. there are a lot of good illustrations. notice every illustration has a centerline axis drawn in on each tube and all those lines meet in the center of the cluster... i think it says in the text somewhere that all tubes should point at the center of the cluster. we can't bend the cabanes without violating that requirement.
that doesn't mean we can't get away with a little deviation. mine has a number of minor deviations and so far it's stayed together. but obviously when it's not in line it isn't a straight push/pull on the tube anymore and a bent tube wants to bend some more.
and that's all i know about that.



OK. Sooo... My bottom longerons on the double eagle are bent at station 2 and 3.  the plans don't call for any finger straps or gussets. Am I gonna crash and burn?

[Poorman2]

Sam, You read my mind about the top longeron carrying on through on the right side. You answered before I even asked the question. It may just be adding extra weight, but I definately think it would stiffen  the fuselage in that area and have the side benefite of an arm rest. Thanks.

[rockiedog2]

>>>OK. Sooo... My bottom longerons on the double eagle are bent at station 2 and 3.  the plans don't call for any finger straps or gussets. Am I gonna crash and burn?

in my DE plans p3A and 4 there are straps shown at both the top and bottom of the cabanes. (Those straps are a clue that is supposed to be a welded joint instead of bent). If I didn't have those I would definitely add them. Yessir...

Bent longerons are the normal way. No prob there

[Sam Buchanan]

>>>OK. Sooo... My bottom longerons on the double eagle are bent at station 2 and 3.  the plans don't call for any finger straps or gussets. Am I gonna crash and burn?

in my DE plans p3A and 4 there are straps shown at both the top and bottom of the cabanes. (Those straps are a clue that is supposed to be a welded joint instead of bent). If I didn't have those I would definitely add them. Yessir...

Bent longerons are the normal way. No prob there

Things are getting a bit confusing now.

Jim was told Leonard discourages bending the top longeron, but yet bending the lower longerons has been the accepted method of construction for a very long time.

So which is it? Bend or not bend?

I'm saying all this to say that common sense must prevail. Yes, bending structural members is generally not the accepted method, but there can be exceptions. I carefully looked at my project and decided bending the top longeron and the cabanes met my standards. This method may not meet other's standards. Each builder must decide for himself, but be open to all options that are not definitively unsafe.

[rockiedog2]

and I'm still trying to figure out where the confusion is about the tailpost. I've about decided my proof set of plans has a page or something missing as I can't find a reference to .062 in there anywhere. I've never heard of .062 only .058 and .065....062 must be a typo that got missed.
Or something.
I'm going to the shop...things are simpler for me there

[grdev]

When Tim Anderson, the Fed out of Milwaukee, inspected my DE he looked at the .040 finger straps I had welded on the cabanes and stated he was happy to see them on there.  I didn't see them on my XL plans, but I will be welding them on.
A 3/4" .035 slides like a glove in my 7/8 tail post I got from Wicks, no slop, just a slip fit. I'll have to measure the wall on my 7/8, but pretty sure it is .058

[scottiniowa]

When Tim Anderson, the Fed out of Milwaukee, inspected my DE he looked at the .040 finger straps I had welded on the cabanes and stated he was happy to see them on there.  I didn't see them on my XL plans, but I will be welding them on.
A 3/4" .035 slides like a glove in my 7/8 tail post I got from Wicks, no slop, just a slip fit. I'll have to measure the wall on my 7/8, but pretty sure it is .058

[Jlwright]

I am getting the hang of grinding the tubes to fit. I wish I had a pedestal grinder on each side if the table. Seems like I do a lot of walking between the table and grinder. Making slow progress though.

[grdev]

Jim, looking good, your moving right along:)

[scottiniowa]

I am getting the hang of grinding the tubes to fit. I wish I had a pedestal grinder on each side if the table. Seems like I do a lot of walking between the table and grinder. Making slow progress though.

Hi Jim!

Yes a second comment on great progress.

 What has been done many times and is easy to do,- take a 2' square plate (round works too) , put casters (I prefer 3 casters as then I never have a high wheel)  use quick step on locking casters to hold your grinder in location- one swivel, two rigid works fine..   Do your center post up from the plate to desired height to hold your grinder.   If you feel it is vibrating to much just add more weight at the base.  A 3" dia. riser or 4" square is generally stiff enough if 1/4" wall is used.   That way you can have your grinder at hand at all times.  If you spend 2 hours building this and 10 hours of walking, your way money ahead to do it.  Most have all the required items in house.  Casters are cheap as they will be in use the rest of your days.  

Lastly a vice on a very strong post/floor plate-  (not move-able of course) is also a great shop addition and frees up your flat work bench to boot.

Hope this helps.
Scott

[Jlwright]

It does help Scott. I should have thought of that. I have casters and all I need to do is add them to the base. Here we go!

[Jlwright]

I spent most of yesterday forming up station three and ground and fit tubes today. I am really starting to enjoy building the fuselage. Fitting joints are coming much easier now. Having the little laser to keep everything in proper alignment is worth it's weight in gold as far as I am concerned.
The second picture shows the laser pin pointing the location of one of the joints. You might have to zoom in a little to see the red lines.

[grdev]

Looks very professional, great job. I'm jealous!:)