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  #41  
Old 12-31-2017, 01:51 AM
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rvmills rvmills is offline
 
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The stub spars for the Super Six are longer than those of the 8, since -6 spars meet in the middle of the aircraft. The inner ends will be trimmed slightly as well, to set the dihedral of the wings. The spar web is full height for the inboard 2 feet (where it penetrates the fuselage), and then tapers in height slightly, to allow it to fit the top-to-bottom taper of the carbon wing spar. So the stub-spar caps are bent in that plane, and tapered to a thinner thickness at the outer end, for both fit and lightening. With 8 caps, 2 webs, 8 pin blocks, and Steve's nice diagrams and drawings, it was time to make marks, then chips and holes!



One cap was selected as the master, and drilled at 1/8" to start, per the pattern on Steve's diagrams. It was then used to match drill its mate.



Due to the taper at the outer ends, Steve made a tapered wood block to keep everything level during drilling (looks like a cribbage board now!)



The process was a bit painstaking, as the holes start at 1/8", and the match drilling is held together with #5 screws as "clecos". First upsize is to #19, held together with #8 screws. Then in 3 steps, I upsized with 11/64", #15, and 3/16" bits, finally held together with #10 screws. Last step at that point was to #11 holes, for riveting with 3/16" rivets.



Next came the placement of the pin blocks and match drilling the web to those. The pin holes are 24" on center, and the outer one is flush with the end of the web. So each had to be sanded to a taper, in order to fit tightly into the taper bent into the spar caps, and slide into place so the inner pin hole is at the correct y-distance. The small pin that was used to hold the pin blocks together when they were match drilled to each other (seen in the block on the upper right), served double duty as a viewer to see when the pin lined up with the correct y-axis marking.



Once the pin blocks were fit, we milled a slight bevel in the outer pin blocks, to ensure clearance at the outer edge, when the wing main spars are slid onto the stub spars. Another airport bud, Dave Miller helped with that job. Always fun to work in Dave's shop, with cool cars all around!





Here are a couple of shots of the fully drilled, de-burred, and countersunk (where needed) assemblies. One assembled, one "exploded". At least "fully drilled" for this phase... the match drilling inside the fuselage is yet to come. For now, these babies are just about ready for primer, and Steve and I will be joining up shortly to work on that! This phase was just under 6,000 passes with various drill bits, just over 15,000 de-burrings, and 108 holes countersunk. Whew!





Great fun and education working with pros like Steve and Bob!

Happy New Year VAF!

Cheers,
Bob
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Bob Mills
RV-6 "Rocket Six" N600SS
Reno-Stead, NV (KRTS)
Sport Class Air Racing "Race 49"
SARL "Race 49"
West Coast Ravens FFI RV Formation Squadron
APRS Track

Last edited by rvmills : 12-31-2017 at 09:36 AM.
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  #42  
Old 12-31-2017, 08:24 AM
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Great photos and writeup, thanks for sharing.

I need to stop by and see it in person...
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Mike Starkey
VAF 909

Rv-10, N210LM.

Flying as of 12/4/2010

Phase 1 done, 2/4/2011

Sold after 240+ wonderful hours of flight.

"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."

Last edited by Mike S : 12-31-2017 at 08:28 AM.
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  #43  
Old 12-31-2017, 09:26 AM
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rvmills rvmills is offline
 
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Any time Mike, and we need to come see you guys. Steve and I may run down to Dayton after priming (in a couple weekends), to check out a squeezer Paul has, so we'll call ahead! Happy New Year!

Quote:
Originally Posted by Mike S View Post
Great photos and writeup, thanks for sharing.

I need to stop by and see it in person...
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Bob Mills
RV-6 "Rocket Six" N600SS
Reno-Stead, NV (KRTS)
Sport Class Air Racing "Race 49"
SARL "Race 49"
West Coast Ravens FFI RV Formation Squadron
APRS Track
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  #44  
Old 12-31-2017, 09:31 AM
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Quote:
Originally Posted by rvmills View Post
Steve and I may run down to Dayton after priming (in a couple weekends), to check out a squeezer Paul has, so we'll call ahead! Happy New Year!
If it is the new one he got from Dave, bring a truck-----that sucker is heavy

Happy New Year back at ya
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Mike Starkey
VAF 909

Rv-10, N210LM.

Flying as of 12/4/2010

Phase 1 done, 2/4/2011

Sold after 240+ wonderful hours of flight.

"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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  #45  
Old 12-31-2017, 09:57 AM
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Ironflight Ironflight is offline
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Quote:
Originally Posted by Mike S View Post
If it is the new one he got from Dave, bring a truck-----that sucker is heavy

Happy New Year back at ya

Not "the Monster" Mike - the bench-mounted one that we used for the Xenos spars - still about 70 lbs.....

Definitely come down Bob and Steve - I never seem to find time to get up to Stead!
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Editor in Chief - KITPLANES Magazine
RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
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Dayton Valley Airpark (A34)
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  #46  
Old 12-31-2017, 12:25 PM
scsmith scsmith is offline
 
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Default Additional progress

Bob, nice job catching everyone up. all the pictures look great too.

I thought I would add just a few more details and additional progress.

First, we were not very outspoken about it and some folks may be confused because early on, the plan was for full aluminum spars, bonded to the carbon skins. After getting one set of spars all match-drilled for assembly, we changed course and decided to make carbon spars with aluminum stub spars that fit into the fuselage, and mate to the carbon spars with a pair of large diameter pins 24" apart -- just like modern composite sailplanes join their wings. Its a connection that is easy to analyze with high confidence, and we made a proof-test specimen as well that demonstrated a high safety factor. Other advantages of switching to the carbon spars:
- they are 10 lb lighter, per side, including the stub spars and joining pins.
- they allow a much easier connection to the ribs
- no need for a rear fuel tank baffle to close out the fuel tank
- no longer worried about thermal expansion unzipping the spar flange bond, although a later FEA showed it would have been fine.

The upshot of this is that we now have a set of full-span tapered aluminum spars that would fit either an RV-7 or RV-8 (fuselage mating holes not drilled yet) If anyone would be interested in building a set of all-aluminum tapered wings - which means having the means to make 52 individual aluminum ribs - I would help with the design and make you a super deal on the spars.

Back to the current progress: In the last few photos of the wings that Bob posted, you can see the spar and ribs set into the upper wing skin. The corner joints between the ribs and the spar, rear spar, and forward fuel tank baffle, are all joined with 2-ply corner tapes. The corner joints between the ribs and upper wing skin have also all had corner tapes put in, but with release film in between to prevent bonding to the wing skin. This essentially forms bonding flanges on all the ribs that are molded to fit the upper skin.

After that last picture was taken, the entire assembly of spars and ribs was lifted out of the upper skin, and it weighed just 22 lbs!
Then the assembly was set into the lower wing skin, and after a check fit for clearances, all the edges were coated with Hysol EA 9430 structural epoxy to bond to the lower wing skin, and the upper skin was set in place and the upper skin mold set on top of everything.

https://www.facebook.com/photo.php?f...type=3&theater

hmm -- I thought I could use facebook to host a picture and it would paste in here. I'll see if I can get those pictures hosted so they show here.
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Aeronautical Engineer
RV-8 N825RV
IO-360 A1A
WW 200RV
"The Magic Carpet"
Hobbs 490 in 8-1/2 years
also LS-6-15/18 sailplane
VAF donation Dec 2017

Last edited by scsmith : 12-31-2017 at 01:18 PM.
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  #47  
Old 12-31-2017, 12:44 PM
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Bob Kuykendall Bob Kuykendall is offline
 
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Quote:
Originally Posted by scsmith View Post
...and we made a proof-test specimen as well that demonstrated a high safety factor...
For the curious, and for folks who just like to see things go bang, here is the YouTube video of the spar coupon static test:

https://www.youtube.com/watch?v=BBeTSSfe_3Q

For this test, the stresses equivalent to limit load are achieved with ~2100 lbf at the load cell, and ultimate load is at ~3150 lbf. As you can hear in the soundtrack, we expected the failure mode to be failure of the little skin sample glued to the upper spar cap, followed by a crippling failure of the upper cap.

However, the whole thing turned out to have more robustness than Steve's relatively conservative analysis indicated, and the actual failure was a classic diagonal shear unzip between the two inboard mounting points (corresponding to the mounting points for our aluminum stub spars). This at ~5400 lbf, corresponding to limit load * 2.57 or ultimate load * 1.71. Bottom line, it would have been a successful test if it'd held to 3200 lbf, and it went to a little less than twice that. There's a reason we are carbon-based lifeforms!

--Bob K.
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  #48  
Old 12-31-2017, 01:38 PM
scsmith scsmith is offline
 
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Default Next steps:

The next step will be to remove the upper skin, and install the corner tapes where the ribs bond to the lower skin. We will do some clean-up on the raw edges of the bond flange tapes that were molded to the upper skin.

Then, we install a bunch of wing internals, such as aileron bell crank and counterweight system, push rods, tie-down anchor, fuel caps and fuel tank vent lines, fuel pick-up tube, blind fasteners for flap hinges and aileron hinges.

After that, the insides of the fuel tanks will get coated with our secret process for hopefully sealing the tanks well -- a combination of a very low viscosity epoxy followed by a heavy coat of epoxy thickened with a little cabosil.

Then, finally we will be ready to do the final bond of the upper skin.
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Steve Smith
Aeronautical Engineer
RV-8 N825RV
IO-360 A1A
WW 200RV
"The Magic Carpet"
Hobbs 490 in 8-1/2 years
also LS-6-15/18 sailplane
VAF donation Dec 2017
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  #49  
Old 12-31-2017, 09:28 PM
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rvmills rvmills is offline
 
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Quote:
Originally Posted by scsmith View Post
hmm -- I thought I could use facebook to host a picture and it would paste in here. I'll see if I can get those pictures hosted so they show here.
Steve, here are those pics:









Cheers,
Bob
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Bob Mills
RV-6 "Rocket Six" N600SS
Reno-Stead, NV (KRTS)
Sport Class Air Racing "Race 49"
SARL "Race 49"
West Coast Ravens FFI RV Formation Squadron
APRS Track
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