nlappos

Flywise,
As a former helicopter test pilot, I have had my share of similar experiences, they are the meat and substance of flight test, frankly. Can I suggest a few pointers?
1) See if you can duplicate the vibration on the ground. Have a friend shake the engine firmly in first up-down and then lateral motions at a fast frequency, close to what you felt, while you sit in the pilot seat. Have him stop the shaking and let go of the engine so it "bounces" a few more times on its own. Try to think back as to what it felt like, and concentrate as much on the extra bounces because those are the natural frequency of the fuselage that the vibration was exciting. In other words, a vibration gets the airplane shaking, but the airframe shakes at the frequency it likes, not necessarily the frequency the shake started at. Then have the friend go to the wing tip and do the same thing both vertically and at the training edge in a wing twisting manner (torsional). Be sure he shakes it fast enough to make the structure vibrate. Again look for the feeling in the cockpit that you experienced.
2) If the engine were shaken at 5 hz, I am guessing the carbs (582 with Bings?) would bounce too, and make the engine change its throttle setting a little, so the engine would cue you with an rpm change, most likely.
3) The spar is probably not involved, most bad aircraft vibes are true flutter, where the ailerons wiggle and make the wing twist torsionally, and dump lift as they down twist, then increase lift as they up twist. That makes big G's in the cockpit and also big wing stresses. I believe there is no reason not to overkill the flaperon weights, and make them too heavy as a safety/troubleshooting fix. Heavy weights make the flaperons want to not rotate, so they would make lateral controls a bit heavy. 
4) Because you got there already, it might be a good idea to make the next flight at higher altitude, with a parachute. Gulp. 

9460 Hysol, I bet 60 degrees will work fine, here is a copy of the directions:
"2. Mixing the adhesive just prior to use is recommended. The temperature of the separate components prior to mixing is not critical, but they should be close to room temperature."
 
https://tds.us.henkel.com/NA/UT/HNAUTTDS.nsf/web/E26C4A5F8C916DE2882571870000DB25/$File/EA 9460-EN.pdf

I took my spring off and went to a car spring shop, they rebent it in 5 minutes and did it for $20.
The tail wheel is at station 147.5 on my MK IV, so that every 2.6 inches is a degree (one inch per 57 inches is a degree).
I went from the 6" Maule to the 8" Matco (pneumatic, single arm) and I guess I am now a degree or so lower angle at tail touch than before, but the full stall 3 pointers are just as easy as ever, and the landings are softer, the taxiing is noiseless and easy to steer, and I love the new tailwheel.
Here is the full discussion thread: http://www.avidfoxflyers.com/index.php?/topic/4360-tail-wheel-swap-to-a-matco-pneumatic-8/

The way I land, my prop could do the job.....;-)

Get ready, your Hero has decided that our ISP can sell our browsing histories to advertisers (and spy networks?) to make more money. 

Gotta take care with Rotax 2 stroke mufflers. The muffler is a tuned part of the exhaust system, and can cause problems where EGT goes sky high if the standing wave frequency mis-tunes with the piston stroke, since the low pressure phase of that standing wave helps exhaust the cylinder. Severe power loss and possible egt problems can be experienced if the muffler system isn't close to the factory one. There are some sites on the web that discuss it a bit more.

Here is a good shot of the wing on that bird, looks like lots of ribs. Comments Guys?
Here, too, is a PDF on how the various wings are built.

Wing contruction.pdf

I emailed the seller yesterday, he sent me those numbers on the weights. 

Here you go:
EW=498 lbs, MGW = 1100
http://www.ebay.com/itm/1992-Avid-Flyer-Speedwing-/182497270032?hash=item2a7daf5910:g:O34AAOSwYXVY0ISG&vxp=mtr

Mike
I am fairly new here, going on two years, and for what its worth, the various models of the Avid have varying useful loads that might drive your decision a bit. I ended up with a Mark IV "heavy hauler" because the MGW is 1150 lbs and the empty weight is usually about 550 lbs (with a Rotax 585, 65 HP engine) so the useful load is almost 600 lbs!  A Bandit has MGW of 950 lbs, but it is lighter than the IV, as well. It might be a good idea to check the kit to see what the declared MGW is.  A bit of a warning, some owners call their aircraft by a different model number so there can be confusion, the serial number should help know the real deal. Let the "guys" here know what you're looking at and they can confirm.
This forum has lots of info, and also the experts to help you make a good decision. Here is one thread that can help:  http://www.avidfoxflyers.com/index.php?/topic/3895-is-a-bandit-a-iv/
Here is where the models are explained a bit, and the serial numbers decoded: http://avidflyer.wikia.com/wiki/Models
and another: http://www.avidfoxflyers.com/index.php?/topic/540-how-to-tell-if-its-a-mkiv/
One piece of advice I will offer free of charge is to build one for the fun, but buy one in the mean time so you get 3 or 4 years more flying in! Barnstormers has Avids all the time for between 11 and 15K, ready to fly. The biggest problem Avid pilots seem to have is wiping the grins off their faces when the think about flying.
Good Luck and welcome!

Thanks Joey!

Two big deals:
Balance- the parts have to provide control and balance throughout the flight envelope, so the designer has to do some calculations for tail sizing and elevator authority, and main wing location relative to CG. Work with someone who has done it to make basic assumptions for your design.
 Structural strength - the pieces have to stay together through the worst maneuver, often a high speed dive and pullout. This stresses the wing itself (spar strength) and the wing and tail attach points. Based on the loads generated by the pieces (used in the balance calcs above) make the structure able to stand 1 1/2 times those loads without bending or breaking. Remember, the FAA would like the wings to stand 4 g's on a normal aircraft, and an experimental shouldn't compromise on this basic strength. One way to assure strength is to load the structure up with sand bags that test it.
 
http://aircraftdesign.com/
http://www.sonexaircraft.com/aircraft/xenosdev/xenosarchive3.html

Yea, my Dad was in the 8th Air Force and he said the stories about how cushy it was are true. They rode 4 hours on oxygen to visit some nice tourist towns, and then rode home in time for dinner. A lot of times hundreds of fighters flew by to greet them. He said if it got bumpy, you could walk home on the flak. I guess he was really sad that he never saw real combat. But things were sometimes rough, they lost more airmen in the Mighty Eighth than all the US Marines who died in WWII, difference was they didn't have as many photographers. Funny, he visited dozens of cities, but they never landed........
 The 94th BG, Bury St. Edmunds, England. The smoke is coming from a former FW 190 factory that someone didn't like very much. 

I mounted the small post antenna on my belly, almost between the pedals, so it is on that thin aluminum floor. I just drilled a 1/2" hole and mounted it with a lock washer. This is an excellent ground plane, and also convenient since the short BNC cable just drops down from the panel. The Xponder checks out fine with ATC.

My nose gear is angled pretty sharply aftward. But it is also quite a bit farther aft than yours, I think. About 10 feet...... ;-)

Beautiful aircraft! Good luck.
 

That FAA warning was for new, bad production stock, Joey. Your old install is surely fine. For the antenna, any bnc coax will do:
http://www.ebay.com/itm/2ft-CablesOnline-RG8x-Coax-BNC-Male-Male-Plug-50-ohm-Antenna-Cable-R-BX002-/291130848270?hash=item43c8c0340e:g:28wAAOSwuAVWznhe
 and here is an Ebay cheap ELT antenna:  http://www.ebay.com/itm/like/272504839565?vectorid=229466&lgeo=1&item=272504839565&rmvSB=true

He got too cute, less back pressure and a touch of power would have cured it all, but messed up his spot landing and landing speed. Bound to happen.

  FAA SPORT PILOT RULE
This is a synopsis of the definition of a light sport aircraft category, the requirements to obtain a sport pilot certificate, and requirements to obtain a repairman certificate with a maintenance or inspection rating. View the complete FAA regulation
The Light Sport Aircraft Rule:
The FAA defines a light sport aircraft as an aircraft, other than a helicopter or powered-lift that, since its original certification, has continued to meet the following:
Max. Gross Takeoff Weight
1,320 lbs (1,430 lbs for seaplanes)
Max. Stall Speed
51 mph / 45 knots CAS
Max. Speed in Level Flight (VH)
138 mph / 120 knots CAS
Seats
Two (max.)
Engines / Motors
One (max. if powered.)
Propeller
Fixed-pitch or ground adjustable
Cabin
Unpressurized
Landing Gear
Fixed (except for seaplanes and gliders)

Here is my Weight and Balance on S/N 1174D, a MK IV, it is a pretty standard MK IV with a 582 blue head, and one fuel tank in the right wing. Built by Jim Peet, who paid close attention to weight!
LAPPOS N4052X Weight and Bal.xls

EDMO, one factor to work into the design is the shift of the aerodynamic center of the wing cord as the flaperons/ailerons are made longer. That will shift the balance of the aircraft and affect the CG needed for trimmed flight.
Recall how a Cessna tucks nose down as the flaps are extended. That is caused by the fact that a substantial area of the wing has a longer cord when the flaps are extended, so the lift shifts aft and that makes the nose tuck down, and causes you to need to trim the elevator up (stick aft). The aero center of the wing is generally about 25% of the cord, so if you extend the flaperons/ailerons 4 inches longer, the wing lift will shift about 1" aft, and the balanced CG will as well. I'd be glad to help you estimate the affect on trim, as I am sure other members might also,

That electric gauge is probably not at all accurate enough to balance some carbs. its accuracy is listed at plus and minus 2 psi, which is 103 mm of mercury,

True story on the value of liability insurance:
A friend had a Federal Judge as a father-in-law. This judge drove off the road to avoid one of those pile-ups that occur, he went left and passed thru the opposing lane and off into a flat spot, no harm no foul. But he passed in front of a horse carrier that jack-knifed when the driver slammed on the brakes. Dead horse was a race horse, worth 1 million, or so his lawyers said. The judge's car insurance paid $100K and walked away, his house insurance paid 250k more and also walked (they both simply paid the max the policies had). The Judge lost the liability case, owed the balance of $650K so he lost his house and all his retirement savings. If a Federal Judge could lose his house, imagine one of us fighting in court!
If we plunk down in a field for one of a thousand reasons, no sweat, but if that highway looks better, and two SUVs crash as a result, it could easily be 250K in liability. No Insurance? Never.

Fred, your video is marvelous, and the journey is a once in a lifetime experience. Congratulations on having the moxie to do it, all the more after the difficulty (who hasn't had one??)
Nice job, and thanks for sharing it with us so elegantly.
Nick