I remember my math teacher screaming "Order of operations!" at some of the kids in algebra class that just didn't get it. And in normal circumstances, I'd probably have the inboard and outboard wing panels at least partially framed by now. However, these wings will be built in a rather unconventional way... In other words, this is going to be a pain in the arse. I'll have to assemble the spars and ribs and wrap them, then add the lower diagonal bracing, then the upper sheet. The lower sheeting will be added after the diagonal bracing is added to the upper sheeting... Like I said... a pain in the arse. However... I've convinced myself it'll be worth it in the end. Don't post anything to bust my bubble...

Darth Bubblehead

So, I decided to go with the original ribs because the outboards would need the same mod whichever set I used, but the inboards will just need a spar slot cut, and I can stack them. It's taken all day to get the outboard ribs modified and slotted for the cf spar caps. I have the shear webs dry fit for one side. They graduate from 1/4 to 3/16 and finally to 1/8. So far so good.... the dry fit looks like it should. This will get a joiner box built and wrapped and the rest may get wrapped with un-waxed dental floss... As I said before, the spar gets thinner the further out they go, and so does the wing thickness. Did I mention that this is a pain in the arse?

Looks like clearing weather tomorrow so I will probably paint fence instead of building wings......

Darth Painful

Originally Posted by schrederman

I remember my math teacher screaming "Order of operations!" at some of the kids in algebra class that just didn't get it. And in normal circumstances, I'd probably have the inboard and outboard wing panels at least partially framed by now. However, these wings will be built in a rather unconventional way... In other words, this is going to be a pain in the arse. I'll have to assemble the spars and ribs and wrap them, then add the lower diagonal bracing, then the upper sheet. The lower sheeting will be added after the diagonal bracing is added to the upper sheeting... Like I said... a pain in the arse. However... I've convinced myself it'll be worth it in the end. Don't post anything to bust my bubble...

Darth Bubblehead

Great thread. I always enjoy threads about scratch building. My best ideas have come from reading how other people do it. I agree that wrapping is a pain and did it many ways over the years. I finally gave up and started completely fabricating spars including wrapping with Kevlar tow before starting building the wing when I started using bubble dancer type spars. It did require using nose and tail ribs. Looking forward to the rest of your build. It is good to read about building your model. Good luck on getting a built up wing that is winch and flutter proof.

Originally Posted by schrederman

I remember my math teacher screaming "Order of operations!" at some of the kids in algebra class that just didn't get it. And in normal circumstances, I'd probably have the inboard and outboard wing panels at least partially framed by now. However, these wings will be built in a rather unconventional way... In other words, this is going to be a pain in the arse. I'll have to assemble the spars and ribs and wrap them, then add the lower diagonal bracing, then the upper sheet. The lower sheeting will be added after the diagonal bracing is added to the upper sheeting... Like I said... a pain in the arse. However... I've convinced myself it'll be worth it in the end. Don't post anything to bust my bubble...

Darth Bubblehead

Great thread. I always enjoy threads about scratch building. My best ideas have come from reading how other people do it. I agree that wrapping is a pain and did it many ways over the years. I finally gave up and started completely fabricating spars including wrapping with Kevlar tow before starting building the wing when I started using bubble dancer type spars. It did require using nose and tail ribs. Looking forward to the rest of your build. It is good to read about building your model. Good luck on getting a built up wing that is winch and flutter proof.

Winch and flutter proof... ... Well Chuck, maybe I have one. My journey has now been launched as hard as my FLS winch will launch it... and no flutter after the mods I made. I'll be building this one the same way, which is why I can't just build it onto the bottom sheeting as we traditionally have. We'll see when it's done. The one I flew at Mid South in '02 didn't flutter at first. After a few hard landings it fluttered mildly in a spoilers-closed vertical dive a couple of times. I think this one will be OK with some carefully placed diagonal bracing, as I built into the Journey. That's the goal, anyway...

Painted about 100' of fence today... and the rest of the day I'm consumed with PapaJack duty... not a bad thing...

Darth PapaJack

"Rib mods... not fun."

Others wise known as bright ideas . . . ;>)

Always a pain but so worth it when finished.

I am keeping secret until proof of concept does not fail on a spar for my new Super Esprit wing. Talk about bright ideas . . .


Joe

aka Known smart***

Darth XXXX (and no, not sure what quadruple X would be...), what would be the disadvantage of using multiple smaller spars rather than a tapered spar? I am a lazy builder and am curious-I built an Aquila Grande' using this (albeit for electric and no winch) and it was very simple and strong, with no tapering...see my accurate drawing below :

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I know there is something wrong with it, so please tell me. Tapers give me nightmares, and just reading what you are going thru makes Freddie seem dreamlike...

Kit

Well.... multiple spars mean multiple shear webs, if you're going to take advantage of the strength of cf. For a tapered panel, that's one of the most time consuming parts of the build. Once I got into it it went pretty fast. I have been busy with fence painting and grandkids so I haven't done pictures of the assemblies, but the outboard panel spars are done, except for the joiner boxes and whatever wrapping I decide to do. Tapers are great... you just have to grit your teeth and get with it. And... whatever follows Darth is decided by what's happening at that moment... So right now, after painting about 150' of pipe fence today.... I'll sign off...

Darth Icy Hot...

Lots of time consuming quality tapering involved. Besides the cf, there are the spruce spars of course, and if I am not mistaken, you have also tapered each shear web to correspond to the thinning widths of the spruce/carbon cap spars!

The only time intensive tapering (simple in comparison) I had done so far is with the Windrifter kit where the outboard wings' LE and TE stock have to be narrowed towards the tips. Did it slow and with care also and the end result turned out well.

Speaking of the Windrifter, it utilized an 'I beam spar' system, which is essentially (except stronger) what you are building as a replacement for the tube spars in the original. Had purchased a Shuttle 78 kit but looked at its Al tube spar which I felt would have been to heavy for the recent conditions at the flying site here, so your build is a validation of what I had been thinking for the Al tube spar substitute but without the tapering, cf, and the wrap. No winches or hi-starts here, we just toss 'em off the side of a very large hill when signs (we think ) of an approaching thermal appear.

Originally Posted by schrederman

Well.... multiple spars mean multiple shear webs, if you're going to take advantage of the strength of cf. For a tapered panel, that's one of the most time consuming parts of the build. Once I got into it it went pretty fast. I have been busy with fence painting and grandkids so I haven't done pictures of the assemblies, but the outboard panel spars are done, except for the joiner boxes and whatever wrapping I decide to do. Tapers are great... you just have to grit your teeth and get with it. And... whatever follows Darth is decided by what's happening at that moment... So right now, after painting about 150' of pipe fence today.... I'll sign off...

Darth Icy Hot...

Looks like you had already installed the bottom spar/cf and added the ribs and shear webs when the pics had been taken. Definitely lots of tapering up to this point! Looking forward....

Those assemblies are super light... Keeping the weight out of the tips can only help in flight, especially after launch. They're stiffer than if they had 1/8 X 1/2 hard balsa spars. I'm off of fence duty until after my fly-fishing trip, and it's supposed to rain tomorrow, so there will be pictures and progress... Won something at the raffle tonight at a meeting I attended, so I'm happy about that...

Darth Newicechest...

Darth Yet E? Please take some detail shots of the last few rib bays. I am taking notes...!

Light tips are great. So is light weight construction aft of the shear center. Weight aft of max thickness is the principle disadvantage of multiple spars.

Chuck's right. Weight aft of the thickest part of the wing is to be avoided. Weight forward is the concept I pushed with my Journey project, and will again be illustrated here. The diagonal bracing aft of the spar did little to prevent flutter structurally, and may have in some cases brought it on with more weight aft. That's why I'm adding my torsional stiffening inside the D-tube. I'll be getting busy in a bit... but caffeine comes first....

Darth Asleepatthewheel................

Looks like I'm stalled for a couple of weeks... Sorry but fly fishing beckons and I still have some fence to paint... and TNT is coming up. I need practice and a bit of set up work with the Journey. But fear not... this madness will resume at some point in the near future.

Darth Fishfearme.... (BWAHAHAHA!!!)

Originally Posted by schrederman

Chuck's right. Weight aft of the thickest part of the wing is to be avoided. Weight forward is the concept I pushed with my Journey project, and will again be illustrated here. The diagonal bracing aft of the spar did little to prevent flutter structurally, and may have in some cases brought it on with more weight aft. That's why I'm adding my torsional stiffening inside the D-tube. I'll be getting busy in a bit... but caffeine comes first....

Darth Asleepatthewheel................

I've been researching flutter for over 40 years and never understood how diagonal bracing aft of the spar helps prevent flutter. Why not go geodetic and be done with it. A diagonal rib is no heavier than a square brace.