RV7Ron
Well Known Member
It actually states a max rate of 12,000 fpm...which comes out to about 136mph if my math is correct.
Van's Air Force
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RV-7A Flutter & In-Flight Breakup
- Thread starter Pitts
- Start date
It actually states a max rate of 12,000 fpm...which comes out to about 136mph if my math is correct.
L.Adamson
Well Known Member
Bill Wightman
Well Known Member
Sure looks like flutter
Flutter sure seems to be the probable factor here, the way I see it. The extreme degree of damage; the high airspeeds, and the heavy rudder all indicate/contribute to a likely flutter incident. The pilots apparent inexperience in aerobatic flight may also have been a contributor. Finally, the video DID reveal a sudden onset of airframe vibration during the high speed pull out:
The report talks about overstress as a possible cause for the rudder failure, but I don't think that's a likely explanation, in and of itself. I think, given this pilot's limited aerobatic flight experience, he *may* have ham-fisted the rudder while attempting to follow lead, thus creating the excitation event himself. At any rate, something induced the flutter incident (if it was indeed flutter), be it pilot, wake turbulence, or another external factor.
Flutter sure seems to be the probable factor here, the way I see it. The extreme degree of damage; the high airspeeds, and the heavy rudder all indicate/contribute to a likely flutter incident. The pilots apparent inexperience in aerobatic flight may also have been a contributor. Finally, the video DID reveal a sudden onset of airframe vibration during the high speed pull out:
The report talks about overstress as a possible cause for the rudder failure, but I don't think that's a likely explanation, in and of itself. I think, given this pilot's limited aerobatic flight experience, he *may* have ham-fisted the rudder while attempting to follow lead, thus creating the excitation event himself. At any rate, something induced the flutter incident (if it was indeed flutter), be it pilot, wake turbulence, or another external factor.
In flight breakup
With all respect to the deceased party, it appears this subject dovetails quite appropriately with the missives from Van regarding safety concerns. The speeds being flown by this pilot are extremely fast for an RV-7A and certainly overstressed the empennage. The laws of physics apply to all. The biggest concern here is that, potentially, activities such as this are what could wreak the greatest havoc on the homebuilt aviation community at the hands of the feds. Exceeding Vne is pilot error not a design flaw in the airplane but some individuals in positions of authority would look at this as an opportunity to take draconian measures to limit our chosen lifestyle. What I take away from this is that it is imperative that we all use our heads and not think that since we are building experimental aircraft and are exempt from some of the stricter measures imposed on certified aircraft manufacturers that we are somehow also exempt from the laws of aerodynamics. An airplane crash gets the attention of many individuals in positions of authority who can adversely affect our ability to fly.
With all respect to the deceased party, it appears this subject dovetails quite appropriately with the missives from Van regarding safety concerns. The speeds being flown by this pilot are extremely fast for an RV-7A and certainly overstressed the empennage. The laws of physics apply to all. The biggest concern here is that, potentially, activities such as this are what could wreak the greatest havoc on the homebuilt aviation community at the hands of the feds. Exceeding Vne is pilot error not a design flaw in the airplane but some individuals in positions of authority would look at this as an opportunity to take draconian measures to limit our chosen lifestyle. What I take away from this is that it is imperative that we all use our heads and not think that since we are building experimental aircraft and are exempt from some of the stricter measures imposed on certified aircraft manufacturers that we are somehow also exempt from the laws of aerodynamics. An airplane crash gets the attention of many individuals in positions of authority who can adversely affect our ability to fly.
Brantel
Well Known Member
Before this report, I had a ton of concern about what really happened in this accident. The report settles this in my mind. There is no design flaw associated with this accident.
These planes are not indestructable and this event/report as sad as it is proves it.
Know the limits of yourself and your aircraft!
These planes are not indestructable and this event/report as sad as it is proves it.
Know the limits of yourself and your aircraft!
I agree with most things said here
I do not believe that exceeding Vne with a slightly mis-balanced rudder was the total root cause. If it were, Kahuana and others like him (no offense - I like speed and Rockets and horsepower, and the whole shebang too) would have all experienced similar fates. And un-balanced -3, -4 and -6 rudders would be fluttering all over the place at the mere hint of exceeding Vne (and they don't seem to be).
Again there were certainly other causitive factors - ham-footed rudder excursions, exposed balance horns to high (Vne++) aerodynamic loads, out of balance flight, reduced structural margins (maybe due to the rudder trim tab), flight through wake turbulence, to name a likely few.
And yes it does relate to the movement for improved safety under current discussion. This low time pilot, God rest his soul, went into a far corner of the envelope on little more than a whim. That is not good headwork. It is something we are all capable of doing. We must promote an atmosphere where that kind of excursion is less likely to happen.
This death was preventable.
I do not believe that exceeding Vne with a slightly mis-balanced rudder was the total root cause. If it were, Kahuana and others like him (no offense - I like speed and Rockets and horsepower, and the whole shebang too) would have all experienced similar fates. And un-balanced -3, -4 and -6 rudders would be fluttering all over the place at the mere hint of exceeding Vne (and they don't seem to be).
Again there were certainly other causitive factors - ham-footed rudder excursions, exposed balance horns to high (Vne++) aerodynamic loads, out of balance flight, reduced structural margins (maybe due to the rudder trim tab), flight through wake turbulence, to name a likely few.
And yes it does relate to the movement for improved safety under current discussion. This low time pilot, God rest his soul, went into a far corner of the envelope on little more than a whim. That is not good headwork. It is something we are all capable of doing. We must promote an atmosphere where that kind of excursion is less likely to happen.
This death was preventable.
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RV7Guy
Well Known Member
Very good discussion so far, in my opinion. And I must agree with Gary Reed - This death was preventable.
I have no idea whether it was classic flutter or an over stress due to sudden maneuvering - it could be either one. Accidents rarely have a single cause - they are usually a result of a chain of errors. You can over speed in calm air, and not have a problem. You can hit a nasty wake (and yes, the RV has a very sharp wake if you've ever done a tail chase!) at slow speed and not have a problem. You can hit a nasty wake and get an upset, and overspeed in the recovery and not have a problem - if you have enough altitude.
This was unfortunately a low time pilot with very little aerobatic time doing extreme maneuvers (note that the report didn't say they were going inverted, just doing "steep turns, PARTIAL rolls, and climbs and descents) solo at low altitude - and well over Vne. How many mistakes are you allowed? Usually, you can get away with one, then go change in to clean underwear. More than that - there are no guarantees.
Was this pilot inspired by all the stories he has heard of and read about in the RV world? Was he going out to have all of the casual fun that we ALL (myself included) often write about? Did he realize that a lot of this "casual" fun is very well planned in advance, and flown by folks with lots and lots of experience? Who knows. But while we may not be our brother's keeper, we might very well be someone's role model, for good or bad - and whether we know it or not.
I'm not worried at all about operating any of Van's designs within their design limits. Going well outside them is not in the cards for this pilot - unless I am wearing a chute, know I can get out, and have lots of altitude. The RV-3 we are building has unbalanced tail surfaces, and the Vne is much lower than in my -8. That is going to take some getting used to I bet - especially with a lot more horsepower than the original design. I plan to be VERY conservative, no matter what others might think. I know that Louise will appreciate that approach. I may look like an old man to the young bucks, but I plan to get a lot older!
Paul
I have no idea whether it was classic flutter or an over stress due to sudden maneuvering - it could be either one. Accidents rarely have a single cause - they are usually a result of a chain of errors. You can over speed in calm air, and not have a problem. You can hit a nasty wake (and yes, the RV has a very sharp wake if you've ever done a tail chase!) at slow speed and not have a problem. You can hit a nasty wake and get an upset, and overspeed in the recovery and not have a problem - if you have enough altitude.
This was unfortunately a low time pilot with very little aerobatic time doing extreme maneuvers (note that the report didn't say they were going inverted, just doing "steep turns, PARTIAL rolls, and climbs and descents) solo at low altitude - and well over Vne. How many mistakes are you allowed? Usually, you can get away with one, then go change in to clean underwear. More than that - there are no guarantees.
Was this pilot inspired by all the stories he has heard of and read about in the RV world? Was he going out to have all of the casual fun that we ALL (myself included) often write about? Did he realize that a lot of this "casual" fun is very well planned in advance, and flown by folks with lots and lots of experience? Who knows. But while we may not be our brother's keeper, we might very well be someone's role model, for good or bad - and whether we know it or not.
I'm not worried at all about operating any of Van's designs within their design limits. Going well outside them is not in the cards for this pilot - unless I am wearing a chute, know I can get out, and have lots of altitude. The RV-3 we are building has unbalanced tail surfaces, and the Vne is much lower than in my -8. That is going to take some getting used to I bet - especially with a lot more horsepower than the original design. I plan to be VERY conservative, no matter what others might think. I know that Louise will appreciate that approach. I may look like an old man to the young bucks, but I plan to get a lot older!
Paul
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lostpilot28
Well Known Member
Yep, that's what I was going to say. The only thing is, that only applies if the airplane is pointed straight down. If that 12,000 fpm descent includes a forward component, then it could be significantly faster. Obviously the only relevence here is the forward speed of the airplane.
RV10inOz
Well Known Member
Paul.........Again you have nailed it pretty well.
I have scanned through this thread, and nowhere has anyone mentioned the effect of TAS.
In this accident it probably had nothing to do with it. They were low levels and cold most likley. But for everyone elses benefit remember this.
Flutter is a product of TRUE AIRSPEED, not dynamic pressure or IAS.
Van has written about this in relation to VNE before. I am sure Paul and Kevin could do a better job of talking about this too.
Again it may not have added many extra knots, but the flutter margin in this plane may have been reduced a bit, and 240 to 250k TAS may have been where the lines intersected.
I have scanned through this thread, and nowhere has anyone mentioned the effect of TAS.
In this accident it probably had nothing to do with it. They were low levels and cold most likley. But for everyone elses benefit remember this.
Flutter is a product of TRUE AIRSPEED, not dynamic pressure or IAS.
Van has written about this in relation to VNE before. I am sure Paul and Kevin could do a better job of talking about this too.
Again it may not have added many extra knots, but the flutter margin in this plane may have been reduced a bit, and 240 to 250k TAS may have been where the lines intersected.
skylor
Well Known Member
160 knots velocity at 45 degrees nose down equates to approximately 12,000 FPM descent rate.
vlittle
Well Known Member
One comment that was provided in the report was that the trailing edge was riveted with -4 rather than -3 rivets, but there was no indication that it had been bonded with proseal or epoxy such as recommended in the instructions.
Also, since the trailing edge is double countersunk, using -4 rivets could mean that they were not properly set. This means that they would not provide full strength and would very easily pull out.
Torsion of the rudder could have sheared or popped the trailing edge rivets. This torsion could have been caused by flutter or excessive yaw input. The rudder is not a symmetrical shape, so a large force caused by pilot input could provide this torsion.
V
Also, since the trailing edge is double countersunk, using -4 rivets could mean that they were not properly set. This means that they would not provide full strength and would very easily pull out.
Torsion of the rudder could have sheared or popped the trailing edge rivets. This torsion could have been caused by flutter or excessive yaw input. The rudder is not a symmetrical shape, so a large force caused by pilot input could provide this torsion.
V
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Wayne Gillispie
Well Known Member
I know that the rudder trailing edge can split open with a strong wind gust
if no proseal is used. Sealant was not mentioned, but from the looks of the shiny remaining skin and straight paint line possibly not. I did not prime mine but with or without primer I had enough excess sealant squeeze forward of the avex wedge that it would not have left a straight line.
Also since 1/8" rivets were used this may indicate a possible wavy trailing edge and redo. The rudder trailing edge will remain much straighter if proseal is used per build plans and allowed to cure for several days. On a roughened, unpainted surface proseal can add alot of shear strength to that joint.
Very informative. Keeps me building per the plans. We need to really think long and hard before deviating on the engine, fuel system or flight controls. Even if proseal was used properly...109 kts over Va/34 kts over Vne is alot.
if no proseal is used. Sealant was not mentioned, but from the looks of the shiny remaining skin and straight paint line possibly not. I did not prime mine but with or without primer I had enough excess sealant squeeze forward of the avex wedge that it would not have left a straight line.
Also since 1/8" rivets were used this may indicate a possible wavy trailing edge and redo. The rudder trailing edge will remain much straighter if proseal is used per build plans and allowed to cure for several days. On a roughened, unpainted surface proseal can add alot of shear strength to that joint.
Very informative. Keeps me building per the plans. We need to really think long and hard before deviating on the engine, fuel system or flight controls. Even if proseal was used properly...109 kts over Va/34 kts over Vne is alot.
Wayne Gillispie
Well Known Member
Vern, now that was not planned
That is the only other thing that I could think of after reading all of that. I had also noticed several prior post mentioning how strong the rudder is. Depends on how it was built. Per plans yes. Primer applied to all surfaces beneath sealant, no roughing up of metal with 150 grit or no sealant, no.
That is the only other thing that I could think of after reading all of that. I had also noticed several prior post mentioning how strong the rudder is. Depends on how it was built. Per plans yes. Primer applied to all surfaces beneath sealant, no roughing up of metal with 150 grit or no sealant, no.
panhandler1956
Well Known Member
Good input
Wayne may have uncovered another link in the chain. The trailing edge could have been deformed and that might make it more prone to futter. Maybe an aero guy could comment.
Wayne may have uncovered another link in the chain. The trailing edge could have been deformed and that might make it more prone to futter. Maybe an aero guy could comment.
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N941WR
Legacy Member
Vne for the -9/9A is 210 MPH.
Not likely a fastener failure. If it had been, then the hinge brackets would not have been ripped off the VS.
Not likely. A few years back a -9A in South America had a wire strike which cut the VS and rudder right off, equal with the top of the fuselage, IIRC. The pilot was able to fly the plane and made an uneventful landing.
Again it was not just a combination of excess speed and a slightly less than spec rudder balance that caused flutter or overstress of this rudder assembly. (Many, many rudders, way less balanced have gone just as fast without dire consequences).
A construction flaw (poor riveting, missing sealant, crimped trailing edge, or something similar) could have contributed.
Again I wonder about a rudder trim tab. This statement "Numerous parts of the rudder, including the right aluminum skin and rudder TRAILING EDGE WEDGE, had separated from the main rudder structure and were located within 100 meters of the vertical stabilizer" seems to indicate that there was a trim wedge.
It is not hard for me to imagine that the assymetric load and bending moment produced by a trim wedge or trim tab at 235 KIAS could buckle the skin of a poorly built rudder (or maybe even a well built one).
Certainly a trailing edge tab, poorly secured to a weak trailing edge going into a flutter mode, could account for this kind of a failure.
Once the rudder failed (in two pieces) the stab vertical spar might be severly taxed.
All speculation.
If you look at fixed trim tabs on faster aircraft (turbo props), they are often secured at both sides of the trailing edge, not just cantilevered off of one side like most RV installations I have seen. This produces a very stiff (flutter resistant) tab. Further, if the tab does not span between two stiffeners, it transfers a buckling load to the skins between stiffeners - not very strong or stiff and actually could induce oil canning in the skin it is riveted to.
An .032" hunk of aluminum, poorly riveted to a "flimsy" trailing edge, not supported by stiffeners, seems like a low stiffness, low mass, very excitable flutter target to me.
Just thinkin'. Any insight from aero engineers out there???
A construction flaw (poor riveting, missing sealant, crimped trailing edge, or something similar) could have contributed.
Again I wonder about a rudder trim tab. This statement "Numerous parts of the rudder, including the right aluminum skin and rudder TRAILING EDGE WEDGE, had separated from the main rudder structure and were located within 100 meters of the vertical stabilizer" seems to indicate that there was a trim wedge.
It is not hard for me to imagine that the assymetric load and bending moment produced by a trim wedge or trim tab at 235 KIAS could buckle the skin of a poorly built rudder (or maybe even a well built one).
Certainly a trailing edge tab, poorly secured to a weak trailing edge going into a flutter mode, could account for this kind of a failure.
Once the rudder failed (in two pieces) the stab vertical spar might be severly taxed.
All speculation.
If you look at fixed trim tabs on faster aircraft (turbo props), they are often secured at both sides of the trailing edge, not just cantilevered off of one side like most RV installations I have seen. This produces a very stiff (flutter resistant) tab. Further, if the tab does not span between two stiffeners, it transfers a buckling load to the skins between stiffeners - not very strong or stiff and actually could induce oil canning in the skin it is riveted to.
An .032" hunk of aluminum, poorly riveted to a "flimsy" trailing edge, not supported by stiffeners, seems like a low stiffness, low mass, very excitable flutter target to me.
Just thinkin'. Any insight from aero engineers out there???
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Thanks Brantel.
Still leaves open the possibility of a fluttering trim tab. As I recall, flutter is directly proportional to stiffness, mass and speed. A recent thread questioned the stiffness of the standard kit elevator trim tab. I am only suggesting that the same scrutiny should apply to the (sometimes flimsy and slightly "slap dash") fixed trim tabs on many RV rudders - probably OK at conservative speed - maybe not so ok at Vne +35..
Could this have been one of those??
Again speculation as we don't even know if one was mounted.
Still leaves open the possibility of a fluttering trim tab. As I recall, flutter is directly proportional to stiffness, mass and speed. A recent thread questioned the stiffness of the standard kit elevator trim tab. I am only suggesting that the same scrutiny should apply to the (sometimes flimsy and slightly "slap dash") fixed trim tabs on many RV rudders - probably OK at conservative speed - maybe not so ok at Vne +35..
Could this have been one of those??
Again speculation as we don't even know if one was mounted.
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N941WR
Legacy Member
There is no trim tab on the rudder, and that is what failed, not the elevator.
As for the glue on the wedge, Van's recommends it to hold the thing together while you rivet it. However, it is not required. Mine has none.
Wayne Gillispie
Well Known Member
Sealant is per plans on the RV-10.
We used it in many similiar applications in the military. It adds some to the tensile strength, but much more to the shear strength. Shear stress is what that joint is subjected to mostly. When you drill out those 3/32" skin dimples and install 1/8" "oops" rivets in place, you are left with less bearing area at the rivet head/skin interface. Then like Vern said the 1/8" rivets may have been underbucked. Possibly then shaven down. More than likely the rivets stayed with the avex wedge.
Gary, yes trim tab is a possibility too.
I find it hard to believe that Van's Aircraft, aeronautical engineers, a&p's and builders before us on here have not asked these same questions. That was one of the best investigations I have read in a long time. I am just assuming Van's was involved throughout the investigation. Of course I am just going by a picture that I zoomed in on so I may be totally off.
Build by the plans, fly it per Van's and we should be fine.
We used it in many similiar applications in the military. It adds some to the tensile strength, but much more to the shear strength. Shear stress is what that joint is subjected to mostly. When you drill out those 3/32" skin dimples and install 1/8" "oops" rivets in place, you are left with less bearing area at the rivet head/skin interface. Then like Vern said the 1/8" rivets may have been underbucked. Possibly then shaven down. More than likely the rivets stayed with the avex wedge.
Gary, yes trim tab is a possibility too.
I find it hard to believe that Van's Aircraft, aeronautical engineers, a&p's and builders before us on here have not asked these same questions. That was one of the best investigations I have read in a long time. I am just assuming Van's was involved throughout the investigation. Of course I am just going by a picture that I zoomed in on so I may be totally off.
Build by the plans, fly it per Van's and we should be fine.
lostpilot28
Well Known Member
Right...you guys are missing my point.
I'm trying to say that 12,000 fpm descent is not in and of itself a bad thing. Even as you pointed out, at a 45-degree angle, you're still not even getting close to Vne. An earlier post mentioned the descent rate in a "holy cow!" type of tone, but I am trying to convey that those rates are not unusual. I think I passed 11,000 feet ASCENT on a loop during Phase 1 testing with an aerobatic test pilot. Entry speed of 175 mph and a 4G pull...going up the front side of that loop is a high rate, as is going down the backside.My over-all point is that no-one should focus on that number (fpm descent), but they should be looking at the pilot's Vne.
Quick question regarding what someone should do in the event they're pointed down (let's say on the back side of a loop or a split S) and you're rapidly approaching Vne. Let's say your doing over 200 mph pointed straight down. But, as in this case, you're only pulling 3 G's. I would think that loading up your wings to 4.5 or even 5 G's would better your situation, assuming you could grunt through it without blacking out. Wouldn't you be managing your speed at the cost of increased drag?
I hope I never have to find out, but I would think the safer thing to do is pull as many G's as the airframe could take to keep your speed under control. Thoughts?
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L.Adamson
Well Known Member
Very common, but so is the offset vertical stabilizer on numerous Van's models. The engine is offset too. Therefor, some aircraft just don't need the tab. My 6A does, as the stab is straight. Am I worried about it fluttering in flight?...........not really. If anything, it would serve to keep the rudder aligned with the air stream. Wouldn't be anymore offset than an offset stab would be. Besides, these tabs and wedges have been held on with duct tape, double side tape & glue, without the benefit of rivets. Just doesn't seem loke a lot of stress on them.
L.Adamson --- RV6A
Wayne Gillispie
Well Known Member
For RV-10 Sec 5H Riveted Trailing Edges...
Van's recommends it to help keep the trailing edge straight. Personally, I believe it also adds a tremendous amount of strength too. So, I guess one could build without the sealant if they choose to. It is experimental.
Many may skip reading Sec 1-5 and go on to building the Vertical Stabilizer in Sec 6, Rudder in 7. At that point as a builder we're pretty inexperienced with surface preparation, cleaning, priming, sealant mixing/application, riveting, etc. Then we come to an avex wedge that must be mach csk on both sides and then rivets "double flush" set at an angle. Assemble it all with a nice straight edge. Easier said than done sometimes.
I have always thought of the rudder as the "not as important flight control". I would have thought that it would have kept on flying even without the vs/rudder like the one mentioned above getting sheared off by a cable.
Van's recommends it to help keep the trailing edge straight. Personally, I believe it also adds a tremendous amount of strength too. So, I guess one could build without the sealant if they choose to. It is experimental.
Many may skip reading Sec 1-5 and go on to building the Vertical Stabilizer in Sec 6, Rudder in 7. At that point as a builder we're pretty inexperienced with surface preparation, cleaning, priming, sealant mixing/application, riveting, etc. Then we come to an avex wedge that must be mach csk on both sides and then rivets "double flush" set at an angle. Assemble it all with a nice straight edge. Easier said than done sometimes.
I have always thought of the rudder as the "not as important flight control". I would have thought that it would have kept on flying even without the vs/rudder like the one mentioned above getting sheared off by a cable.
Jamie
Well Known Member
Lots of speculation in this thread about the trailing edge and I think jumping to conclusions that this was a contributing cause. If the rudder failed catastrophically (as control surfaces often do in flutter) the trailing edge of course would be ripped open. Look at the pictures -- half of the rudder is missing. I would not expect that joint to remain riveted if the lower half of the rudder departed the aircraft.
You could just as easily argue (based on photos in the report) that the rudder fluttered, the counterbalance arm (which would suffer a lot of damage due to the inertia of the counterbalance weight) failed and ripped the rudder in two.
The point is the failure mode of the rudder is almost irrelevant. At 20% above Vne you are a test pilot and along for the ride.
You could just as easily argue (based on photos in the report) that the rudder fluttered, the counterbalance arm (which would suffer a lot of damage due to the inertia of the counterbalance weight) failed and ripped the rudder in two.
The point is the failure mode of the rudder is almost irrelevant. At 20% above Vne you are a test pilot and along for the ride.
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Kyle Boatright
Well Known Member
Exactly. Add in the fact that this overspeed occurred during maneuvering flight and possibly in the vicinity of wake turbulence, and I don't see it as an airframe problem.
Airplanes have published limits for a reason.
RVG8tor
Well Known Member
Load kills energy
You are correct if you are going down hill fast the last thing you want to do is back off on the "G", the load is actually and energy killing maneuver. Pull but remain with in aircraft limits until nose is approaching the horizon and then zoom up until you get your speed under control
Do some level 3-4 G level turns and see how your airspeed bleeds off, it is the same in the vertical its just that you have God's "G" working for or against you.
I am surprised at the number of guys that go out and do this stuff without any training. Flying trail off another airplane is not like aerobatics, it is more complicated, doable but you need someone with experience. The lead in this case has some of the blame because he did not monitor his own energy state, a good lead knows that #2 is having to pull more and go faster or slower in some cases to stay in position.
From a safety standpoint since so many are flying formation and doing extended trail stuff, the community needs to come up with some standards, power setting, do-not-exceed parameters as lead and wing and wingmen need to know when to call "Knock it off" and break out from the formation.
I have to add that this was an exceptionally written accident report something on can learn from.
Fly smart, fly safe but most importantly have fun doing both.
Right...you guys are missing my point.
My over-all point is that no-one should focus on that number (fpm descent), but they should be looking at the pilot's Vne.
Quick question regarding what someone should do in the event they're pointed down (let's say on the back side of a loop or a split S) and you're rapidly approaching Vne. Let's say your doing over 200 mph pointed straight down. But, as in this case, you're only pulling 3 G's. I would think that loading up your wings to 4.5 or even 5 G's would better your situation, assuming you could grunt through it without blacking out. Wouldn't you be managing your speed at the cost of increased drag?
I hope I never have to find out, but I would think the safer thing to do is pull as many G's as the airframe could take to keep your speed under control. Thoughts?
You are correct if you are going down hill fast the last thing you want to do is back off on the "G", the load is actually and energy killing maneuver. Pull but remain with in aircraft limits until nose is approaching the horizon and then zoom up until you get your speed under control
Do some level 3-4 G level turns and see how your airspeed bleeds off, it is the same in the vertical its just that you have God's "G" working for or against you.
I am surprised at the number of guys that go out and do this stuff without any training. Flying trail off another airplane is not like aerobatics, it is more complicated, doable but you need someone with experience. The lead in this case has some of the blame because he did not monitor his own energy state, a good lead knows that #2 is having to pull more and go faster or slower in some cases to stay in position.
From a safety standpoint since so many are flying formation and doing extended trail stuff, the community needs to come up with some standards, power setting, do-not-exceed parameters as lead and wing and wingmen need to know when to call "Knock it off" and break out from the formation.
I have to add that this was an exceptionally written accident report something on can learn from.
Fly smart, fly safe but most importantly have fun doing both.
Update on the lab reports: I have submitted a request, I was hoping they could come from my contact at the TSB directly, but unfortunately it has to go through the ATI department (Access To Information) and needs approval. I'll update when I find out how that goes. Hopefully it won't take *too* long.
They did say that the reports are PDF's, but if they're too large they would have to snail mail copies. I have requested that they try emailing it even if it's big, and barring that to burn them to a CD for mailing. We'll see what happens.
They did say that the reports are PDF's, but if they're too large they would have to snail mail copies. I have requested that they try emailing it even if it's big, and barring that to burn them to a CD for mailing. We'll see what happens.
aarvig
Well Known Member
I totally agree with this opinion. The aircraft had over two hundred trouble free hours on it. Exceeding Vne and Va may cause ANY aircraft to breakup. I am sure we all remember the Airbus that came apart over the Atlantic. Va and Vne are not arbitrary numbers they are laws of physics. I have been worried about this accident for some time now. Reading this report gives me a large amount of relief and confidence in what I am building will be structurally sound. Having said that, I am reminded that we all make mistakes and some pay with their lives. My heart goes out to his family.
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lostpilot28
Well Known Member
Agreed, but I've done loops at 3,000 AGL and I believe those rates are typical. What I do NOT think is typical is going 40 mph over Vne. In any attitude that's bad, but especially in a descent.
LifeofReiley
Well Known Member
I'm very conservative flying my 7A, but I elected to keep the 8 rudder due to my personal opinion on the design of the newer 9 rudder going on the 7, as I feel it's not really designed for the 7 craft...
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I would suggest to consult with VANs and other knowlagble people in this area and not leave it for chance. You also may want to wait and balance it after paint, if you are going to paint the plane. When I finished mine, after painting my elevators were on not balanced any more and after talking to Vans, they recommend to balance them as closely as possible. I end up adding about 5.5 OZ of weight to my elevator to get them fully balanced.
LifeofReiley
Well Known Member
Sorry...
Guys and Gals,
This paint... balance is BS !!! Fly by Van's numbers and everything will be fine balanced/painted or NOT.
Guys and Gals,
This paint... balance is BS !!! Fly by Van's numbers and everything will be fine balanced/painted or NOT.
This paint... balance is BS !!! Fly by Van's numbers and everything will be fine balanced/painted or NOT.
I certainly agree that understanding and flying below Vne is critical, Reiley, but if Mehrdad spoke directly with Van's, and they said balancing after paint is important too, should we be quick to discount that advice? If so, why? (I'm not asking as an argument, rather, I'm honestly trying to learn here.)
--Stephen
islandmonkey
Well Known Member
Guys and Gals,
This paint... balance is BS !!! Fly by Van's numbers and everything will be fine balanced/painted or NOT.
I could not believe my eyes when I saw that this was posted by an EAA tech councillor.
Surly, balancing the flying surface after its been painted, increases the margin of safety. I know thats what I would want. Just imagine if an aerobatic manoever goes TU and you end up pointing downhill. It is very easy to exceed vne and maybe get close to non balanced flutter speed.
For many years, I have been nastily criticized because I have tried to get the message out that an RV is NOT an aircraft for hard aerobatics.
Or even an aerobatic trainer, because people make mistakes and fall out of maneuvers when they are learning them. And if someone makes one mistake, they're likely to make another mistake, with the nose pointing straight down.
An RV is simply not built as strongly as a Sukhoi, or an Extra, or a Zivko, or MX2, despite what you might think. It is NOT an unlimited-capable aerobatic airplane, and if you fly it like one, you will break it, sooner or later.
Andrew Philips (two hangars down from me) was not the first person to fly the snot out of an RV, and have it break up in flight on him. Please don't do that. It's really depressing for the rest of us.
An RV is wonderful at doing "gentleman aerobatics" - rolls, loops and combinations - in the hands of an experienced aerobatic pilot. Paper aside for a moment, so is a Cessna 172. I tell people to not do any aerobatics in an RV, that they wouldn't consider doing in a 172, from purely an engineering standpoint.
Bob Hoover could do wonderful aerobatics in an Shrike Commander. Bobby Younkin could blow your mind with a Beech 18. But both of these gentlemen were superb aerobatic pilots, and flew very carefully, imposing absolute minimum load on their airframes to complete the maneuvers.
Most of us don't fly as well as Bob Hoover or Bobby Younkin. It's funny, almost all pilots think they are "above average" which of course is a statistical impossibility.
Please don't fly your RV hard and fast. Feel free to personally attack me again for expressing that opinion, but I'm alive after all these decades and there are plenty of people who disagree with me, who aren't.
pierre smith
Well Known Member
Very well said.
Your advice is really sound but you and I know that there will nevertheless, be guys who don't heed it....just keep watching the NTSB reports.
Thanks,
Your advice is really sound but you and I know that there will nevertheless, be guys who don't heed it....just keep watching the NTSB reports.
Thanks,
islandmonkey
Well Known Member
Totally agree with you Pitts
My point was that balancing the control surfaces, after painting, gives you an increased margin of safety over and above not balancing them.
I like big safety margins!!!
My point was that balancing the control surfaces, after painting, gives you an increased margin of safety over and above not balancing them.
I like big safety margins!!!
Of course! Rightly or wrongly, in a nutshell, the TSB report concluded that there was a 100 knot delta between Van's published Vne (200 knots) and Van's flutter speed (300 knots), and that:
1) the painter used up 50 knots of that delta with paint and filler aft of the hinge point with no re-balancing afterwards, and
2) the pilot used up the other 50 knots of that delta by flying the aircraft considerably past Vne.
Like most other accidents, there is more than a single cause - a chain of events, lined up holes in the swiss cheese, pick your abstraction model.
The pilot probably could have gotten away with flying 50 knots over Vne if his control surfaces had been re-balanced after painting.
Being a belts and suspenders kind of guy, fixing both #1 and #2 above seem like good ideas.
Build your RV carefully, and fly it gently, and it will give you many years of uneventful flying.
Don't do this to it:
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I liked your input better when you talked about arobatics
I liked it better when you said to not do anything in an RV that you would not do in a Cessna 172. The speed in this case was strictly do to the way he was flying the plane. I have modified my RV-6A for speed, have flown it in many races, and I firmly believe it is physically impossible to get even a highly modified RV to 234 kts (indicated or TAS) in steady state level flight. The fastest example in 5 years of SARL racing no one has come close even in ground speed with a tail wind. The fastest speed recorded was a straight line race of several hundred miles with a healthy tail wind.
AirVenture Cup 2008 7/27/08 RV Blue RV-8 Huft, John 217.17
THE SPEED IN THE CANADIAN CASE WAS A RESULT OF THE WAY THE PLANE WAS FLOWN JUST AS MUCH AS THE INFLIGHT BREAKUP. LET'S FOCUS ON THE CAUSE WHICH IS THE WAY THE PLANE WAS FLOWN AND TREAT RESULTS AS RESULTS.
Bob Axsom
I liked it better when you said to not do anything in an RV that you would not do in a Cessna 172. The speed in this case was strictly do to the way he was flying the plane. I have modified my RV-6A for speed, have flown it in many races, and I firmly believe it is physically impossible to get even a highly modified RV to 234 kts (indicated or TAS) in steady state level flight. The fastest example in 5 years of SARL racing no one has come close even in ground speed with a tail wind. The fastest speed recorded was a straight line race of several hundred miles with a healthy tail wind.
AirVenture Cup 2008 7/27/08 RV Blue RV-8 Huft, John 217.17
THE SPEED IN THE CANADIAN CASE WAS A RESULT OF THE WAY THE PLANE WAS FLOWN JUST AS MUCH AS THE INFLIGHT BREAKUP. LET'S FOCUS ON THE CAUSE WHICH IS THE WAY THE PLANE WAS FLOWN AND TREAT RESULTS AS RESULTS.
Bob Axsom
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David-aviator
Well Known Member
First 300 hours....
I agree.
From all indications the pilot was well liked, shared his building and flying experience and appeared confident. Its the last part that did him in - unwarranted confidence.
There was a time when new pilots were specially cautioned about the first 300 hours after training. At least it was so in the military. We were confident but that confidence was a false feeling built up doing all the so-called confidence building stuff with an instructor in the back seat. They knew the risks and kept accidents to a minimum during training by constant supervision.
Where guys got into trouble was during advanced training which was mostly solo. I remember one happy go lucky guy, the life of a party, very confident. He flew into the side of a hill in his F-100 on a gunnery range doing at least 400 knots. The first 300 hours can kill anyone.
That's what happened to Andrew, rest his soul. He has a lot of company if there is a special place for pilots.
I agree.
From all indications the pilot was well liked, shared his building and flying experience and appeared confident. Its the last part that did him in - unwarranted confidence.
There was a time when new pilots were specially cautioned about the first 300 hours after training. At least it was so in the military. We were confident but that confidence was a false feeling built up doing all the so-called confidence building stuff with an instructor in the back seat. They knew the risks and kept accidents to a minimum during training by constant supervision.
Where guys got into trouble was during advanced training which was mostly solo. I remember one happy go lucky guy, the life of a party, very confident. He flew into the side of a hill in his F-100 on a gunnery range doing at least 400 knots. The first 300 hours can kill anyone.
That's what happened to Andrew, rest his soul. He has a lot of company if there is a special place for pilots.
aarvig
Well Known Member
Guys and Gals,
This paint... balance is BS !!! Fly by Van's numbers and everything will be fine balanced/painted or NOT.
No offense Reiley but this is opinion presented as fact. Obviously the Canadian transportation board found this as one link in the sequence of "events" or "findings" that led to an in-flight breakup. Discarding this as "BS" (when you are an EAA Tech Counsellor) could lead someone to believe it is not important. The conclusion didn't state that paint or balance was a single causative factor but that it likely played a role. I do agree with your advice to fly by the numbers.
Ditto this
LifeofReiley
Well Known Member
I never said that flying surfaces should not be balanced! It's a really good idea. IMHO, balanced flying surfaces was not going to help this gentleman out in any way and that was my point.
