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RV-7/7A In-Flight Breakup Accident Information

Thanks for the reminder Carl, I was aware of this but was previously less concerned with it, until this thread & learning of the possible -9 rudder's narrow margin for error with respect to -7's Vne. I suppose if I do decide to keep my -9 rudder on my -7 then probably should consider having an EFIS -and with a good audible alert.

I wonder if anybody knows of Van's position on this issue yet?
My instinct is to stick with what they provide, but if the -8 rudder on a -7 was at least an option that they endorsed then I'd be more likely to consider it.

Thanks again, and I REALLY appreciate all the input this thread is drawing, yay for VAF!

You're quite welcome. As been noted, the very early RV-7s had the RV-8 rudder. Van's SB 02-6-1 (https://www.vansaircraft.com/service-information-and-revisions/sb-2-6-1/) addresses the change to the -9/-7 rudder. Reading it carefully will show that the -8 rudder and the -9/-7 rudder shipped with kits after 5/20/2002 are acceptable to Van's. There is no urging to early RV-7 kit owners with the -8 rudders to retrofit the -9/-7 rudder, i.e., Van's states in the SB that any owner could request the -9/-7 rudder if desired. Also note the comments by Van's in the SB regarding spin recovery characteristics of the RV-7 with either rudder installed. Both are acceptable.

Regarding modern EFIS capabilities: The ability to set Vne in terms of TAS is quite helpful and assists in the safe operation of the airplane now that Vne is in terms of TAS for RV's. In addition to showing TAS below the IAS tape, it dynamically adjusts the Vne (Redline) on the IAS tape as a function of Altitude and OAT.

In the screenshot below from the SkyView Touch in my RV-8, at 9,800' with an OAT of 36 Deg F, Vne = ~196 MPH IAS as indicated by the Redline on the speed tape. Also, note that Vne (230 MPH TAS) and Vno (193 MPH IAS) are within 3 MPH. At slightly above this altitude (~10,000'), Vne will be lower than Vno.

i-Nq7JcgK-M.png


Here is a screenshot I took at 16,120' MSL and an OAT of 25 Deg F. Note that Vne at that altitude and OAT is only approximately 175 MPH IAS. I am descending at 49% power at only 600 FPM, and I’m close to Vne; so it’s easy to overspeed in the descent from higher altitudes in an RV if one is not careful. Note also that there is no Yellow band since Vno is higher the Vne.

i-5csHKL5-M.png


And they are colorful to look at!
 
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Large rudder

The large rudder and vertical stab structure was designed for the RV9 with a maneuvering speed of 118 mph. Remember that when you are trying to do
a slow roll or knife edge with lots of rudder input at higher speeds. Maybe a hammerhead that turns into a tail slide....or ???
 
The spreadsheet in post #1 has been updated to add the link to the Australian Transport Safety Bureau Final Report for the RV-7A (VH-XWI) accident that occurred on 4/23/2021.
 
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The spreadsheet in post #1 has been updated to add the link to the Australian Transport Safety Bureau Final Report for the RV-7A (VH-XWI) accident that occurred on 4/23/2021.

Thanks for adding the link Carl.

I believe we’re allowed to talk about the VH-XWI accident now that the final report is out. WOW, that’s some description of get there itis.
 
Autopilot

The lesson to be learned from the Australian accident is to know how to use the autopilot and if conditions dictate use the autopilot to get out of trouble.
 
The spreadsheet in post #1 has been updated to add the link to the Australian Transport Safety Bureau Final Report for the RV-7A (VH-XWI) accident that occurred on 4/23/2021.

At the last recorded GPS position (0952:04), the aircraft was at a recorded altitude of about 6,000 ft, where it had rolled 165° to the left and pitched down 41°. It was descending at more than 10,000 ft/min at an indicated airspeed of 224 kt and was accelerating at 15 kt/s

Why are we even talking about "in-flight break-ups" here? This was going to end badly regardless, at this point. In excess of Vne, likely *well* in excess, some sort of structural failure seems almost inevitable here.

Same lesson as before about not exceeding the envelope, with the additional lesson that *keeps being repeated* about how deadly continued VFR flight into IMC is.
 
Just me

I have noticed that when things get tense, people will drive faster , etc, just to get it over with. Seems to be what happened here and to Kobe Bryant. A lesson we seem to keep on re-learning
 
Why are we even talking about "in-flight break-ups" here? This was going to end badly regardless, at this point. In excess of Vne, likely *well* in excess, some sort of structural failure seems almost inevitable here.

Same lesson as before about not exceeding the envelope, with the additional lesson that *keeps being repeated* about how deadly continued VFR flight into IMC is.

You're certainly correct that this flight seemed destined to end badly.

But the inflight break-up is relevant because the -6/6A, -7/7A (original small rudder) and -8/8A most certainly must have had egregious departures from the flight envelope but yet do not end up with flutter. So some of us have postulated the -7/7A with the -9/9A rudder may not have the same flutter margins as the rest of the Vans fleet.
 
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You're certainly correct that this flight seemed destined to end badly.

But the inflight break-up is relevant because the -6/6A, -7/7A (small rudder) and -8/8A most certainly must have had egregious departures from the flight envelope but yet do not end up with flutter. So some of us have postulated the -7/7A with the -9/9A rudder may not have the same flutter margins as the rest of the Vans fleet.

That's an hypothesis, but I see two problems here. First, the *assumption* that the other models "must have had egregious departures from the flight envelope". It may be likely, but there's zero evidence one way or the other, so any analysis after that is contingent upon that assumption. That's the null hypothesis, in statistics-speak.

Second, I don't think anyone knows *what* the flutter margins are on any of the models, do they? That's the *designer's* realm, the engineer's, not the pilot's.

In the end, does it really matter for the cases discussed here? Does anyone think a plane that is upside-down, headed downhill at 10,000 fpm, doing 244 knots and rapidly increasing *isn't* going to break up pretty damned soon, *regardless* of margin? If the flutter onset speed is 250 knots, or 260, or 270, would it really have made any difference?

And if you're under control and going balls-out at nearly 250 knots, you are *well* beyond Vne and should question how you got there and why. 205, heck, I can see that, but by the time you get to 20% over Vne, you've made some serious mistakes, and counting on "more margin" to save your bacon is, IMO, illogical and foolish.

Show me a case of a 7 breaking up 210 due to flutter, I'll listen. Keep bringing cases of pilots exceeding Vne by 20% or more, VFR into IMC or aerobatics they shouldn't have been doing, and I'm off to bar for a beer instead. :)
 
That's an hypothesis, but I see two problems here. First, the *assumption* that the other models "must have had egregious departures from the flight envelope". It may be likely, but there's zero evidence one way or the other, so any analysis after that is contingent upon that assumption. That's the null hypothesis, in statistics-speak.

Second, I don't think anyone knows *what* the flutter margins are on any of the models, do they? That's the *designer's* realm, the engineer's, not the pilot's.

In the end, does it really matter for the cases discussed here? Does anyone think a plane that is upside-down, headed downhill at 10,000 fpm, doing 244 knots and rapidly increasing *isn't* going to break up pretty damned soon, *regardless* of margin? If the flutter onset speed is 250 knots, or 260, or 270, would it really have made any difference?

And if you're under control and going balls-out at nearly 250 knots, you are *well* beyond Vne and should question how you got there and why. 205, heck, I can see that, but by the time you get to 20% over Vne, you've made some serious mistakes, and counting on "more margin" to save your bacon is, IMO, illogical and foolish.

Show me a case of a 7 breaking up 210 due to flutter, I'll listen. Keep bringing cases of pilots exceeding Vne by 20% or more, VFR into IMC or aerobatics they shouldn't have been doing, and I'm off to bar for a beer instead. :)

Your absolutely correct that this is just a hypothesis and there may be other forces at work.

But I know one thing, if I’m flying a -7/7a with an original small (RV-8/8A) rudder, I’m flying an aircraft with no history of breaking up in flight.

Vans approves the smaller rudder, the smaller rudder -7/7A has never broken up as far as we know and the difference in spin characteristic is trivial. So for some of us, that’s enough.
 
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I'll just stay below Vne regardless of rudder size. Others can tempt fate as they wish.
I think it's safe to say that none of the pilots in Carl N's list of accident reports launched with the intention of going past Vne. But whether it was from inattention, lack of aerobatic skill/training or spatial disorientation, they did. We're kidding ourselves if we think it couldn't happen to us.

ds
 
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Given the low absolute numbers of occurrences there’s little basis to assume that the result would have been different with the smaller rudder. Or an RV6/8/9/10/14.
Is there an unreported series of small rudder planes split S-ing out of the clouds intact having run 30+ knots through VNE?
 
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Given the low absolute numbers of occurrences there’s little basis to assume that the result would have been different with the smaller rudder. Or an RV6/8/9/10/14.
Is there an unreported series of small rudder planes split S-ing out of the clouds intact having run 30+ knots through VNE?

You have of course highlighted one of the many problems with statistics in general. Anyone that has done this is highly unlikely to put it into any kind of database.

One place to find this might be the savvyaviation.com data - there's a lot of info there, and if they chose to release anonymous raw data I think we could learn some interesting things.
 
Given the low absolute numbers of occurrences there’s little basis to assume that the result would have been different with the smaller rudder. Or an RV6/8/9/10/14.
Flipping that around, is it reasonable to believe that -7s are any more likely to be exposed to speeds past Vne than other aerobatic RV models? I don't think so.

I think it *is* reasonable to assume that single- and tandem-seat RVs are favored by aerobatic pilots and folks looking for a fighter-like experience, and to me that makes them more likely to be flown past Vne and so exposed to the risk of structural failure. And we don't see similar failure modes in other RV models as far as I know. If someone is tracking this question I'd love to see your data.

Leaving aside statistics and small sample sizes, the only thing that can be stated with some certainty from at least three of Carl's accident reports is that there's a flutter-induced failure mode in big-rudder -7s and -9s somewhere past Vne. Three of the reports imply that it's *well past* Vne, which is comforting, although the ATSB report isn't really clear about how they determined when the flutter event happened.

This is E-AB after all, and I guess it's up to each of us. Are we ok with a cliff at that point past Vne, or do we want a more gradual failure in the event of an inadvertent large airspeed excursion? I vote for the latter, and that's why I'm strongly considering putting the -8 rudder back on my -7. I think Van's wants a different failure scenario as well, given the updated internal structure on -10 and -14 rudders.

ds
 
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torsional stiffness

Well, I witnessed first hand some of those nicely bent -14 rudders at KOSH this Summer. Not being an Engineer, I would of course not pronounce myself...
 
Atlantic City RV7

This would be a good time for an in depth review of the Atlantic City RV7A accident. The pilot was clearly trying to learn to do aileron rolls on his own.
Some of the previous attempts resulting in loss of control had been witnessed by a pilot in another airplane who had been "coaching" the accident pilots attempts.
That RV7 had incurred wind damage to the rudder while parked outside. The rudder was repaired by the pilot who was not the builder.
The pilot had been in a previous accident that resulted from fuel exhaustion in a non EAB.
I had many aerobatic students who had no previous aerobatic experience. Early on their first lesson I was successful in talking most of them thru their first attempt at aileron rolls. I did not demonstrate the maneuver first and rarely had to touch the controls.
 
Well, I witnessed first hand some of those nicely bent -14 rudders at KOSH this Summer. Not being an Engineer, I would of course not pronounce myself...

Yes, and a number of 10's, 7A's, 9A's...

It would be an interesting exercise to devise a test/rig to apply a twisting moment to each rudder and measure the amount of deformation and yield at failure (unzip).
 
I think it *is* reasonable to assume that single- and tandem-seat RVs are favored by aerobatic pilots and folks looking for a fighter-like experience, and to me that makes them more likely to be flown past Vne and so exposed to the risk of structural failure.

Or, those aerobatic pilots are properly trained and *less* likely to exceed Vne by 20% or more because they've been *taught* how to do aerobatics within the envelope?

Are we ok with a cliff at that point past Vne, or do we want a more gradual failure in the event of an inadvertent large airspeed excursion?

Isn't flutter onset essentially *always* a "cliff"? What makes you think there's some gradual onset of failure at 245 knots or more that you can then pull out of a 10000 fpm accelerating downward flightpath and not tear the airplane apart?
 
Or, those aerobatic pilots are properly trained and *less* likely to exceed Vne by 20% or more because they've been *taught* how to do aerobatics within the envelope?

I think this sums it up best.
If you are a 7 builder and you are nervous about what occurs well past Vne then the best mitigation is investing in the training to ensure that dosent occur.
By all means switch to a smaller tail if you think there’s some marginal difference in the point at which your airplane disintegrates but remember you’re trading away something else that the original designer thought was more important.
 
-----SNIP------
By all means switch to a smaller tail if you think there’s some marginal difference in the point at which your airplane disintegrates but remember you’re trading away something else that the original designer thought was more important.

This is starting to look like the never ending primer debates.

I'll just say, the Service Bulletin allows the smaller original rudder or the larger RV-9 rudder. So, for us using the original rudder, we are in compliance with the Van's engineering parameters. And if one want to use the larger rudder, the same applies.
 
Given the low absolute numbers of occurrences

Is it a low number?

How many RV-7s are flying? What rate of in flight breakups? 1 in 300? Is that low?

We are told you don't do aerobatics in non-aerobatic aircraft, even if the manoeuvre should not exceed G and airspeed limits because they do not have enough margin if it goes wrong.

Maybe the RV-7 with the large rudder is in the same category. Maybe the rudder design and low drag means it also doesn't have enough margin for safe aerobatics?

Are there other aerobatic aircraft with a similar history of in flight breakups?
 
Problem thread

This is the problem with this thread. With no scientific research people are jumping to a conclusion that the RV-7 tail is not safe. No one has presented any data to support the conclusion that the tail can not handle aerobatics or does not have sufficient safety margin.

If the accidents convince you to install a different rudder, great. It’s your airplane. If you think the existing rudder is just fine, great it’s your airplane.

But can we stop questioning the safety of the entire model fleet. Because the only thing we know is exceeding VNE is a problem and in a few cases have led to accidents.

To answer the previous poster there are 1909 flying RV-7s that Vans knows about.
 
No one has presented any data to support the conclusion that the tail can not handle aerobatics or does not have sufficient safety margin.

...

To answer the previous poster there are 1909 flying RV-7s that Vans knows about.

So the rate of inflight breakups is around 1 in 300. That seems to be data that indicates there is a problem.

I accept that these aircraft were well over VNE. But then you have to ask why so many RV-7s end up over VNE? Is that something that needs addressing?

Is there any other aircraft with the same rate of in flight breakups?
 
So the rate of inflight breakups is around 1 in 300. That seems to be data that indicates there is a problem.

I accept that these aircraft were well over VNE. But then you have to ask why so many RV-7s end up over VNE? Is that something that needs addressing?

Is there any other aircraft with the same rate of in flight breakups?

I think we identified THREE that were structural failures, would be less than 1 in 600 KNOWN aircraft, *and* that all (with one exception) were known to have greatly exceed Vne (the exception being that it was not recovered).

This is the thing that sticks in my craw with this "debate". There's almost no information that indicates a problem *exists* AT ALL, and yet some people, presumably without aeronautical engineering degrees or, at least, the actual engineering and test data to back up their claims, have reached the conclusion that a different rudder than the designers provide is "better". Fine, great, it's your plane, do what you want, BUT...people continue to spread this idea around that the one provided by Van's is "less safe" or "has less margin", possibly affecting the impressions and understanding of thousands of pilots, based on nothing more than a tiny fraction of the fleet, NONE of which failed at less than Vne*1.2 (approx, some much higher).

I think this sort of speculation and TLAR "engineering" is unsound at best, and dangerous at worst if applied to the wrong things.

"in God we trust; all others bring data." Well, where's the data on flutter onset speeds and margins above Vne*1.x or whatever with the different components, done under controlled conditions?

Not to mention...criminy, how far above Vne do you expect the airframe to save your bacon from your botched aerobatic maneuver or continued VFR flight into IMC? You want more, fine, but IMHO it's doing a disservice to try to convince the community based on essentially *nothing* that what they have isn't "good enough" and might get them killed.

Rant over. :)
 
I think we identified THREE that were structural failures, would be less than 1 in 600 KNOWN aircraft, *and* that all (with one exception) were known to have greatly exceed Vne (the exception being that it was not recovered).

I think there are 6 or 7 with the same signature rudder failure.

All I'm saying is that in flight breakups are bad, and they have repeatedly happened with the RV-7. Enough that it is a pattern that deserves attention to try to prevent it.

If it's due to pilots exceeding VNE (I agree it is), how do you stop pilots from exceeding VNE?
 
I think there are 6 or 7 with the same signature rudder failure.

All I'm saying is that in flight breakups are bad, and they have repeatedly happened with the RV-7. Enough that it is a pattern that deserves attention to try to prevent it.

If it's due to pilots exceeding VNE (I agree it is), how do you stop pilots from exceeding VNE?

I'll repost my summary of the spreadsheet with some updating:

1. Preliminary report only, cause undetermined yet.
2. Exceeded Vne by > 20% in a 10000 fpm nose-down attitude, accelerating at 15 kts/s, after several hairy VFR into IMC encounters and a seemingly steadfast refusal to give up trying to get killed
3. Exceeded Vne by > 20% (44 knots).
4. "There were no clear indications that any of the [empennage] components that fractured in overstress did so before ground impact or independently of the bird strike."
5. "damage to the horizontal stabilizers and elevators that was consistent with a downward failure in positive overload. The loads required to fail the horizontal stabilizers and elevators cannot be generated from normal flight or
control movements. Such failures would have required an abrupt pull back on the stick and corresponding movement of the elevator to a trailing-edge-up position, at speeds greater than the airplane's maneuvering speed."
6. Probable cause undetermined because wreckage was not recovered (sunk in 500' of water).
7. "At the time of the inflight breakup, the airplane was traveling 20 knots above the published never exceed speed."
8. Exceeded Vne by 34 knots.

So 4 that, yep, are similar...grossly exceeding Vne. I don't even know why item 6 is in this list, since the wreckage was never found.

As I said, you want to experiment around and put on a different rudder, that's fine, I have no gripe with that. It's just irresponsible to say or imply that the existing rudder is *unsafe*.

I'll ask again...anybody have actual data on what the flutter onset speed is for identical aircraft with each of the two rudders? Anyone? Anyone? Are you *sure* they're not nearly identical, or (gasp) even lower with the replacement? How would you know?

I just re-read all of this thread, paying attention to see if there were any posts with *actual* engineering data. Found essentially none, but you know what I did find *plenty* of? "It just feels _______". "It seems to me that _________." "I believe _______." and the like.

Sorry, that ain't engineering...
 
And the first one in the list? Here's all we know, from the preliminary report:

Security video captured the airplane in a steep nose down spiral before it impacted terrain. Several pieces of aircraft structure were seen falling from the airplane as it descended to the ground.

Absolutely NOTHING about WHAT parts those were. Might have been anything, or parts that separated during a very high-speed descending spiral, or nothing at all. This one shouldn't be included in the list (yet, maybe not ever).

Including the ones that *aren't* what you're claiming them to be is just a scare tactic, even if unintended, because it makes the numbers larger. And few people will go to the trouble of reading the *actual* reports to see if what's being claimed is actually the case.
 
... and yet some people, presumably without aeronautical engineering degrees or, at least, the actual engineering and test data to back up their claims, have reached the conclusion that a different rudder than the designers provide is "better". Fine, great, it's your plane, do what you want, BUT...people continue to spread this idea around that the one provided by Van's is "less safe" or "has less margin", possibly affecting the impressions and understanding of thousands of pilots, based on nothing more than a tiny fraction of the fleet, NONE of which failed at less than Vne*1.2 (approx, some much higher).

Rant over. :)

I am an aerospace engineer and spent my entire career in flutter and aeroelasticity, as an engineer, DER, and manager at a large commercial airplane company. After retiring from that company, spent several years in the Transport Airplane Directorate of the FAA as their flutter and aeroelasticity specialist.

The -8 rudder will increase the fin/rudder flutter margins as well as the strength margins compared to those of the -9/-7 rudder, as I've outlined in post #16 of this thread. And Van's endorses the use of either rudder on the RV-7/7A.

As you say, it's your airplane and you can do what you want, but no other Van's airplane has the number of in-flight structural failures that the -7/7A has, and it appears to involve the use of the -9 rudder (unless RV-8 pilots really are just better than RV-7 pilots!).

So I hope your serious about ending your ranting (as you rightly called it) and let people decide for themselves.
 
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I accept that these aircraft were well over VNE. But then you have to ask why so many RV-7s end up over VNE? Is that something that needs addressing?

Yes, that is a problem - but it's a PILOT problem, not an equipment problem. You're not going to fix stupid by changing the rudder, they'll just rip something else off.
 
Yes, that is a problem - but it's a PILOT problem, not an equipment problem. You're not going to fix stupid by changing the rudder, they'll just rip something else off.

I would tend to agree with you however the statistics are pretty compelling. The RV6 as a example has as far as I can tell never suffered a inflight breakup. The only one I am aware of in the 8 was a wing failure in a over G situation. You can’t fix stupid but are 6 and 8 drivers dramatically smarter than 7 drivers?
 
I would tend to agree with you however the statistics are pretty compelling. The RV6 as a example has as far as I can tell never suffered a inflight breakup. The only one I am aware of in the 8 was a wing failure in a over G situation. You can’t fix stupid but are 6 and 8 drivers dramatically smarter than 7 drivers?

From a strict engineering and evidentiary perspective, that answer is just as likely as the one about poor design.
 
Excellent! So what IS the flutter onset speed of the smaller rudder?

Enough of a flutter speed increase to prevent the RV-8s from suffering the same malady that seems to affect the RV-7s. The only in-flight breakup of an RV-8/8A that I am aware of is the Van’s-owned RV-8 demonstrator (N58RV). That accident was thoroughly investigated by Van’s and the NTSB and was shown to be caused by a failure of the wing due to a positive overload. If my memory is lacking here and there have been other in-flight breakups of RV-8s, please let me know so I can correct the record.
 
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Or, those aerobatic pilots are properly trained and *less* likely to exceed Vne by 20% or more because they've been *taught* how to do aerobatics within the envelope?
Maybe. :)

Isn't flutter onset essentially *always* a "cliff"? What makes you think there's some gradual onset of failure at 245 knots or more that you can then pull out of a 10000 fpm accelerating downward flightpath and not tear the airplane apart?
Your assumption that flutter is the first failure mode/limitation past Vne, isn't necessarily correct. Vne is defined as 90 percent of Vd, the design dive speed that the manufacturer chose to demonstrate. The hazards past that could be buffeting/vibration, increasing structural loads, etc. If I screwed up on a downline and went well past Vne, I'd like to know that the failure mode was "gradual", to use your words, or something I had some limited control over - like keeping the wings and stab on by gentle use of the stick.

ds

ps - Tagging on to Carl's words, I'm an engineer as well. I spent a fair chunk of the Air Force and FAA portions of my career as a Flight Test Engineer and Test Director in fixed and rotary wing aircraft. I'm also a consultant DER. I've intentionally been past Vne more than once in high-risk tests, which is more than enough. I learned enough about margins around Vd to pay attention to the flutter/aeroelastic experts; Carl's position as the FAA's flutter specialist for transport category aircraft is all I need to know about his expertise.
 
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From a strict engineering and evidentiary perspective, that answer is just as likely as the one about poor design.

The common failure involves a joint that doesn't exist in the RV6/8, so I think the evidence is much stronger than for RV6/8 pilots being smarter.

But I wouldn't call it poor design (is that what people are upset about?)

I would say it is discovery of a common first point of failure that doesn't exist in the RV6/8. Evidence from the RV6/8 suggests there is a fix that would improve margins enough to avoid these in flight breakups and save lives.

The looming question is what about the RV-14? I don't think there are enough flying yet to be confident it won't see the same failures. I know the rudder structure is different, but is it different enough to avoid the problem?
 
Maybe. :)


Your assumption that flutter is the first failure mode/limitation past Vne, isn't necessarily correct. Vne is defined as 90 percent of Vd, the design dive speed that the manufacturer chose to demonstrate. The hazards past that could be buffeting/vibration, increasing structural loads, etc. If I screwed up on a downline and went well past Vne, I'd like to know that the failure mode was "gradual", to use your words, or something I had some limited control over - like keeping the wings and stab on by gentle use of the stick.

ds

ps - Tagging on to Carl's words, I'm an engineer as well. I spent a fair chunk of the Air Force and FAA portions of my career as a Flight Test Engineer and Test Director in fixed and rotary wing aircraft. I'm also a consultant DER. I've intentionally been past Vne more than once in high-risk tests, which is more than enough. I learned enough about margins around Vd to pay attention to the flutter/aeroelastic experts; Carl's position as the FAA's flutter specialist for transport category aircraft is all I need to know about his expertise.

Thanks for the info in the 1st paragraph. I'm an engineer as well, 30+ years, but not aero (rather, systems, in aerospace). So my preferred verification method is Test, followed closely by Analysis. Somewhere lower down is Inspection. And way down (like off the list) is "Seems as if...", TLAR, etc. I'll certainly defer to an aero engineer's overall assessment.

Still seems to me that this is a solution in search of a problem. Don't go VFR into IMC, get aerobatic training before you do aerobatics, and know your V-speeds seem to be correct answers to "how do I not go so fast that I break the airplane?". THOSE are the root causes of the failures, not the hardware.
 
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This has been a really good thread. I kind of view the “potential” problem/solution as money in the bank. Yes, if you have enough money in the bank to pay your bills every month, you’re probably in pretty good shape….but it never hurts to have a little extra emergency funds.

I posted in another RV-7 thread with similar questions. In that thread the OP raised the question and wondered if the 14 rudder would fit/work on his 7? He felt as though the 14 rudder offered a better/stronger internal structure and decided to give it a try. He reported that he really liked the results and that the 14 rudder was working well on his 7. So that does bring up the question as to why the 14 rudder isn’t standard equipment on the 7/9? Even if the 14 rudder becomes standard equipment on the 7 and 9, I’m still personally firmly in the 8 rudder camp and think it’s a better choice. If for no other reason, it looks a lot better.

…..snip…..The looming question is what about the RV-14? I don't think there are enough flying yet to be confident it won't see the same failures. I know the rudder structure is different, but is it different enough to avoid the problem?

The pros and cons have been argued pretty thoroughly in this thread and everyone has their own reasons for liking one flavor or the other.

Now this brings me back to the question I asked in that other 7 thread: How would the 14 fly with an 8 rudder? I know it’s never been done before and you’d be a “test pilot”, but the question still remains. Not being an aeronautical engineer, I’m merely looking at it and asking the questions from a novice point of view. This is how I see it:

1. It’s known that the 8 rudder works perfectly fine on the 7/9 and many people, including myself, argue it’s superior to that of the 9.

2. It’s known that the 14 uses the 9 VS and rudder. Yes, there may be some internal structural differences, but for arguments sake, they’re the same.

3. It’s known that the 14 flys perfectly fine with the 7/9 rudder so one could easily conclude that the overall aerodynamics/flight characteristics of the 14 are similar enough to that of the 7/9 that the 7/9 VS and rudder works well on the 14.

4. I know it’s never been attempted before, and you’d be a “test pilot”, but with the known facts listed above, it’d be an interesting discussion and to point to specific things , compare and contrast, that would be detrimental if attempted.
 
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How would the 14 fly with an 8 rudder? I know it’s never been done before and you’d be a “test pilot”, but the question still remains.

My question is why bother? The 14 flies just fine with the 14 rudder that comes as part of the kit. :confused:
 
My question is why bother? The 14 flies just fine with the 14 rudder that comes as part of the kit. :confused:

I’m not saying anyone “should”….I’m just asking the question. As discussed throughout this thread, there’s different schools of thought. I’m firmly in the 8 camp (money in the bank) and believe it’s a better design and offers a safety margin. On top of that, I think it looks a lot better. 😎
 
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I posted in another RV-7 thread with similar questions. In that thread the OP raised the question and wondered if the 14 rudder would fit/work on his 7? He felt as though the 14 rudder offered a better/stronger internal structure and decided to give it a try. He reported that he really liked the results and that the 14 rudder was working well on his 7. So that does bring up the question as to why the 14 rudder isn’t standard equipment on the 7/9? Even if the 14 rudder becomes standard equipment on the 7 and 9, I’m still personally firmly in the 8 rudder camp and think it’s a better choice. If for no other reason, it looks a lot better.



The pros and cons have been argued pretty thoroughly in this thread and everyone has their own reasons for liking one flavor or the other.

Now this brings me back to the question I asked in that other 7 thread: How would the 14 fly with an 8 rudder? I know it’s never been done before and you’d be a “test pilot”, but the question still remains. Not being an aeronautical engineer, I’m merely looking at it and asking the questions from a novice point of view. This is how I see it:

1. It’s known that the 8 rudder works perfectly fine on the 7/9 and many people, including myself, argue it’s superior to that of the 9.

2. It’s known that the 14 uses the 9 VS and rudder. Yes, there may be some internal structural differences, but for arguments sake, they’re the same.

3. It’s known that the 14 flys perfectly fine with the 7/9 rudder so one could easily conclude that the overall aerodynamics/flight characteristics of the 14 are similar enough to that of the 7/9 that the 7/9 VS and rudder works well on the 14.

4. I know it’s never been attempted before, and you’d be a “test pilot”, but with the known facts listed above, it’d be an interesting discussion and to point to specific things , compare and contrast, that would be detrimental if attempted.

I think your question was thoroughly discussed in the RV-7 subforum when you posted it there. Let's not rehash it again in this Safety subforum thread.
 
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