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From bird strike report: quote "Birds struck the vertical stabilizer causing it to swing top end to the left side of the aircraft which in turn caused the bottom rod end bearing to break, which showed signs of corrosion(post-crash). The rudder bell crank snapped near both rudder cable fittings right side had signs of 45 degree shearing marks and left side showed signs of peeling away down and to the left which is consistent with the vertical being struck by and object from the left side." I doubt pigeon strike/strikes would cause the VS to depart but the canopy definitely would. Quote: "The FAA National Wildlife Strike Database (1990-2015) includes 20 birdstrikes with Rock Pigeon at or above 2000 feet AGL; five of those strikes occurred between 4,000 and 6,000 feet AGL" I had no idea pigeons would be flying at 4,000 to 6,000 AGL. |
Another option
Another option is to put a -8 rudder on the -7. More than one person has gone that route for looks and in my opinion, more margin.
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Are the -8 and -7 rudders the same size? In other words, will the -8 rudder fit on a -7 without any modifications?
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Yes
Yes, it bolts right up. You need to replace the little fiberglass tip on the vertical. Keep in mind that the larger -7 rudder will give a little better spin recovery over the -8 rudder (1 to 1.5 turns if I recall). Given the data gathered to date, I suspect that unrecoverable spins are not on the radar like the unzipped rudders are.
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Vans originally shipped RV-7 kits with the RV-8 rudder, then switched somewhere before 2004 because as Craig mentioned the -7's spin recovery characteristics are apparently better with the -9 rudder.
C-GNDY and N174BK were both overspeed when their failures occurred and it's reasonable to assume that this accident airplane was as well. I haven't seen any accidents like this in RV-8s, or small-tail -7s and it's also reasonable to assume that they're flying the same mission profiles - maybe even more possibility of overspeed with -8s because they're more often flown aerobatically. Does that mean that the -7 has more overspeed margin (in either flutter or overload) with an -8 rudder? Only Van's knows the answer to that question. But in the absence of any hard engineering information I'm questioning whether to finish my -7 as-is or go back to the -8 rudder, just for the warm fuzzy of perceived margin. I know it's legally dangerous for Van's to respond in a public forum, but perhaps they'll find another way to educate us -7 builders on this topic. Dave |
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Please excuse my ignorance and a bit of a thread drift, but would someone please describe in a little more clear concise way the differences in the 7 and 8 rudder? It would also be helpful if someone could maybe post a picture or two of the differences and or a link that details the differences. I'm about to start building the rudder for my -7 and if there's really a benefit to going with the 8 rudder, then now's the time for me to make that change.
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This line of inquiry needs to be in a separate thread. Please move the RV-X tail discussion to its own thread so the discussion of this tragic accident can proceed uninterrupted. Thanks |
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