Been looking for information on whether trim tabs should be mass balanced,but could not find anything conclusive; however if one `googles `SAWE`Paper3020`,by Space Electronics,there is good stuff about mass balance and the effects of `flutter`.
I have had aileron flutter on an aircraft,coincidentally an 80% scale Mustang;on completion of some testing for `G` limits and `rolling `g`pull-outs.It started at about 160kts,as I was doing a little `flypast` for the owner at an airfield at about 3-400ft.It sounded like a `Gatling` gun firing,and looking at the left wing I could not see it,the right was quite steady.Vibration was also quite severe,and I had to climb,reduce power almost to the stall to stop it.After landing, the aileron bellcrank and pushrod were found to be sheared .Also,although made to specification ,there was insufficient mass-balance on the ailerons.The wings were wooden,and stressed to +-12 g,but I`m sure if they had been metal,it may have been different. The flutter started instantly,and at a speed that I had already tested,but that had obviously weakened the internals.
So, what Lyman and M-B are probably seeing on the video is a series of snapshots of the tailplane vibrating,but the frequency may well be above the camera speed.I also agree that there is a slight distortion/alignment there as well.
If one looks at the photo on P9,#162,to me it appears that there is slightly more `up` elevator than the left one.I`m only gauging that from the shadows on the mass-balances.Now ,if one is putting UP elevator on one side ,and the tab on the opposite side is forcing Down,then there will be a difference in tension on both sets of elevator cables,and on the bolts holding both torque tubes together.Could lead to cable stretch,possibly sufficient to disengage from the pulleys and guides,or cause the bolts to `fret` or loosen.
`Voodoo` appears to have that happen,but there again does not appear to be a comprehensive report about it`s failure either.