RV-4 wings folded

[Steve Barnes]

I called Wayne Stonesipher of Phlogiston Manufacturing a few days after the accident. He was just about ready to have a meeting with Van and told me to call him back the next day. I called him and he told me that the meeting was to adjust the production quantities on the 8 spars but not to stop production.

No modifications were to the spars and from the beginning. Van's seemed to be confident that the spars were not an issue. With thousands of those spars flying, I have not heard of another failure.

Steve

[jrs14855]

I have to take issue with Smokey's statement about 11G's incapacitating the pilot. It's all about the duration. In high performance civilian aerobatic aircraft the duration CAN BE extremely short. In this case a 90 degree pitch change at 11 G is hardly noticeable to an experienced aerobatic pilot.
Far more important however are snap rolls. The G incurred is almost totally dependent on airspeed. The various aerobatic RV's would be very vulnerable to snap rolls entered at too high a speed. This is primarily because of the relatively low stall speed of the RV's. Also the snap roll by nature is an assymetrical maneuver, few if any engineers truly understand the forces acting on an airplane during a high speed snap roll.
A snap roll in the Pitts S1S entered at 135 statute is a 7 G maneuver. The highest G I ever incurred in the S1S was 7.5 and that was an aerobatic sequence flown in moderate to borderline severe turbulence. A typical pull at Vne is 6.5 G.

[jrs14855]

The RV8 crash was in Ripley CA, just south of Blythe. The airplane was over the aerobatic gross by approximately 90#. The elevator trim tab pushrod was disconnected at the tab.
The report does not seem to attach any importance to the tab issue.
Apples to oranges but an elevator tab actuator disconnect in the Pitts S1 will take the stick out of the pilots hands.

[scsmith]

Originally Posted by jrs14855

The RV8 crash was in Ripley CA, just south of Blythe. The airplane was over the aerobatic gross by approximately 90#. The elevator trim tab pushrod was disconnected at the tab.
The report does not seem to attach any importance to the tab issue.
Apples to oranges but an elevator tab actuator disconnect in the Pitts S1 will take the stick out of the pilots hands.

Hmmm, I didn't know about the trim tab disconnect before. This is speculation, but if that happened in flight, it could easily explain an otherwise unexplained reason for the pitch-up that caused the over-g. Its also possible that the trim clevis failed on impact and had nothing to do with the departure.

[rvbuilder2002]

Anyone that has ever been involved with wreckage from a crash like this one will tell you that a lot of stuff is found disconnected.......

[scsmith]

Originally Posted by rvbuilder2002

Anyone that has ever been involved with wreckage from a crash like this one will tell you that a lot of stuff is found disconnected.......

Yeah, doesn't surprise me. I've seen one. Very little was recognizable, let alone connected. Very sobering.

[redhawk]

I know there was a wing failure of a RV3 in Colorado years ago during a aerobatic maneuver. The NTSB report said something about a critical wing bolt or nut that was forgotten during assembly...

[Christopher Murphy]

The 3 has had more issues with the spar...I remember one from about 1979 or so. Pretty sure it was an assembly or modification issue.( wallowed out hole)

How many are doing snap rolls in the -4?

Cm