What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Vne Testing

ChiefPilot

ChiefPilot

Well Known Member
I've heard it both ways:

- There is no need to go beyond the published Vne during phase one because the RVs are such well proven designs, and
- You must go to 110% of Vne to establish that your specific aircraft meets design specifications plus a small margin of safety.

AC90-89a seems mum on the topic.

What say you? Do people commonly flight test to 10% past Vne, right to Vne, or just assume that your bird will hold together to Vne so no need to actually check?
 
It is quite unlikely that your RV will have a flutter issue at speeds of 1.1 VNE or less, unless you have made some major construction screwup.

But, on the small chance that your aircraft has a problem, when would you rather find it:
  • during dedicated flutter testing, when you are by yourself, wearing a parachute, at a safe altitude, over an uninhabited area, mentally prepared to bail out if necessary, or
  • on the day when you screw up and exceed VNE, possibly with a passenger, and not wearing parachutes?
 
Anyone that tells me I HAVE to exceed a published limit (110% of Vne) can do it themselves. I'll likely never listen to anything they have to say on anything ever again either.

To Kevin's point, I'd rather stay within the safety margins all the time. 1500+ hours riding ejection seats, I've never once felt compelled to exceed the published limitations just because I had an "out."

BTW, If you think you can bail out after strucutral failure beyond Vne, you're shooting craps with your life.
 
Last edited:
Old irish golf saying....

Used when you hit a really bad shot that somehow works out.

It's called the "sister in law"
"Your up there laddie, but you know you shouldn't be."
 
You are required to make log book entries on your TESTED speeds to enter phase 2.
During the test phase you are the test pilot or who ever is flying your plane. Its not for boring holes. Its to test the flight envelope of plane.
If your not up to the task, you should pay someone who is.
The verbage to make phase 2 speeks for its self.
You should not put someone in your plane if you have not actually performed the tests that you say you did.
 
Exceed at your peril

As Sig600 stated

'I've never once felt compelled to exceed the published limitations just because I had an "out." '

The aircraft I fly do not have that same "out", but even if they did I do not exceed limits; ever. I believe the design engineers of "certified" aircraft. I will stay with what Van says.
 
Sig600 said:
Anyone that tells me I HAVE to exceed a published limit (110% of Vne) can do it themselves. I'll likely never listen to anything they have to say on anything ever again either.

To Kevin's point, I'd rather stay within the safety margins all the time. 1500+ hours riding ejection seats, I've never once felt compelled to exceed the published limitations just because I had an "out."

BTW, If you think you can bail out after strucutral failure beyond Vne, you're shooting craps with your life.
Click to expand...

I took Kevin's point to be that however unlikely it might be that my plane has a problem, why not positively prove it does not in a controlled situation when you have the preparation & equipment to deal with a bad situation? That line of reasoning is very logical to me.

Although I'm still 6+ months away from first flight, thinking about all the stuff that needs to be done during phase one and doing the project plan to accomplish those tasks makes me think I'll need more than 40 hours to get everything done.
 
ChiefPilot said:
I took Kevin's point to be that however unlikely it might be that my plane has a problem, why not positively prove it does not in a controlled situation when you have the preparation & equipment to deal with a bad situation? That line of reasoning is very logical to me.

Although I'm still 6+ months away from first flight, thinking about all the stuff that needs to be done during phase one and doing the project plan to accomplish those tasks makes me think I'll need more than 40 hours to get everything done.
Click to expand...

You have the right midset Brad.
Take all the time you need. Your given hours in your test phase is just a min.
 
Take the airplane up to 8000' push the nose over and watch the ASI go up to the red line. VNE test done.

Wrong.

You just went through the red line at significantly more than VNE. Van has stated VNE is true airspeed, not indicated air speed. Quite a number of us did not know that until after the fact.

However you do it, be careful and know the criteria for this airplane. It is the first airplane I've flown that has such TAS limitations, not IAS.

dd
 
Sig600 said:
Anyone that tells me I HAVE to exceed a published limit (110% of Vne) can do it themselves. I'll likely never listen to anything they have to say on anything ever again either.

To Kevin's point, I'd rather stay within the safety margins all the time. 1500+ hours riding ejection seats, I've never once felt compelled to exceed the published limitations just because I had an "out."

BTW, If you think you can bail out after strucutral failure beyond Vne, you're shooting craps with your life.
Click to expand...
No one told you that you HAD to exceed VNE. What you HAVE to do is defined by the regulations, not what some random person here suggests you do.

RVs are fairly low drag aircraft, with a relatively high thrust to weight ratio, and a VNE that is much lower than anything with an ejection seat. You'll find that you will be flying within 40 kt of VNE during a significant percentage of your flying time, which means that it doesn't take much of a piloting error or lapse of attention to unintentionally end up on wrong side of VNE.
 
Kevin Horton said:
No one told you that you HAD to exceed VNE. What you HAVE to do is defined by the regulations, not what some random person here suggests you do.

RVs are fairly low drag aircraft, with a relatively high thrust to weight ratio, and a VNE that is much lower than anything with an ejection seat. You'll find that you will be flying within 40 kt of VNE during a significant percentage of your flying time, which means that it doesn't take much of a piloting error or lapse of attention to unintentionally end up on wrong side of VNE.
Click to expand...

My point was that if you do find that failure point, the likelyhood of getting out, even with a chute in a "controlled" setting is 50/50 at best. A structural failure such as that RV-7A that lost it's rudder will impart G's and out of control flight in such a manner that the possibilities are infinate. At those airspeeds with even a modest amount of G, the ability to actually open the canopy and climb out may not be possible. Even at only 3 G's post failure, out of control, I would seriously question the ability of the average person to lift themselves out of the seat. I know I can leg press in excess of 600 pounds, but at 3 G's, there's no way I could physically lift myself out of the seat to egress.

You're right, these planes are slick and over powered. That means it requires a higher level of skill, attention and dicipline to operate inside the lines. Testing the boundaries to make up for inexcusable lapses in attention just doesn't add up to me.
 
Last edited:
op-lims

Don't know about yours but my Op-Lims do not require Vne to be recorded to enter Phase-2.

"I certify that the prescribed flight test hours have been completed and the aircraft is controllable throughout its normal range of speeds and throughout all maneuvers to be executed, has no hazardous operating characteristics or design features, and is safe for operation. The following aircraft operating data has been demonstrated during the flight testing: speeds Vso ______, Vx ______, and Vy ______,
and the weight ______ and CG location ______ at which they were obtained.?

Despite not being required it is my opinion everyone should test to at least VAN's Vne or your own personal limit (whichever is slower) and not beyond. Paint, how well you balanced your counterweights, friction in the system can change the margins from plane-to-plane.

If you do test to Vne, make yourself a IAS to CAS to TAS conversion chart accounting for DA and approach Vne (TAS) in very small increments, reseting all the variables each pass (alt, configuration, power settings, trim, etc.).

Do this test near the end of your test phase after you've gained some proficiency. I contacted and obtained a discrete squawk from ATC prior to this test and asked for some help with airspace deconfliction because this is a decidedly heads-down test sequence requiring 100% pilot-in-the-loop to hold the final Vne at whatever your converted IAS turns out to be. Oh..make sure your OAT is calibrated correctly so you actually know what your DA is first. I used two separate EFIS with two independent OAT probes to manually calculate the local IAS for Vne and compared to their displayed values of TAS through an intermediate range of IAS prior to conducting this test to ensure those calculations were in sync and OAT probe heating affects could be accounted for. The differences were due to Ps errors and accounted for in my chart which is what I flew by..not the EFIS display of TAS. It would be nice if the EFIS manufactures included a means to input the Ps corrections and display CAS but I digress...

BLUF: My -8 safely attained published Vne at both min and max GW at fwd and aft most CG (4 complete tests conducted).

good luck
 
As designed vs. as built

I think the key issue in this discussion is whether an individual aircraft meets the performance capabilities specified by Vans. Though I respect the engineering of these aircraft as designed, I would never take my wife for a flight in my RV without KNOWING I had a margin of safety in MY aircraft for the flight envelope we operate in.

For many RVs, cruise flight at altitude is close enough to redline TAS that a redline test is practically a necessity to ensure safe operation. Better to learn a limitation alone than to take a passenger and not know your safety margin.

M
 
foka4 said:
I think the key issue in this discussion is whether an individual aircraft meets the performance capabilities specified by Vans. Though I respect the engineering of these aircraft as designed, I would never take my wife for a flight in my RV without KNOWING I had a margin of safety in MY aircraft for the flight envelope we operate in.

For many RVs, cruise flight at altitude is close enough to redline TAS that a redline test is practically a necessity to ensure safe operation. Better to learn a limitation alone than to take a passenger and not know your safety margin.

M
Click to expand...

Exactly my point. If you don't test it to failure (which you can only do once), how do you know what that margin of safety is?
 
Margin

The margin of safety I'm most interested in knowing is the margin between where I am operating and where I have tested. This has little to do with published numbers or failure points.

Experimental aircraft give us a lot of benefits, but also some obligations. In a sense, we are all test pilots. I think it's our obligation to test a certain flight envelope (with parachute in a safe piece of airspace), and the operate the aircraft in a smaller envelope thereafter.

We don't have to test to published VNE, but I think it's prudent to set your aircraft's redline several knots slower than the fastest you have test flown it.

M
 
vne testing

In the early EAA era some builders were required to test to 110% of VNE. The wording " controllable throughout its normal range of speeds" tells me that the FAA expects a test to VNE. Very simple solution for this-if you are afraid to test to the recommended VNE, make the VNE on YOUR individual aircraft a number that you are comfortable with.
 
yet they conspicuously leave out the requirement to document Vne. Why? Because they really do not want to tell anyone they have to test to Vne. The word "normal" is not a legal term I assure you.

Only the builder decides what "normal" is but is not required to be documented anywhere.

The Op-Lims for my BD-4 dated 1976 do not require Vne testing or documentation so when and why do you think it was ever REQUIRED to go to 110%?

Going beyond ANY established design limit is simply irresponsible unless you are backed by analysis, and have the requisite skill and experience as well as a genuinely VALID reason to do so. If you disagree then why stop at 110%? why not 120%, 130%. Certainly someone can rationalize this....

I watched a flutter test in the wind tunnel at NASA AMES and what I heard and saw was BRRRAAAAAP, CRACK, BOOM in about 2 microseconds the entire structure destroyed. One instant it was flying nomally in less than a second later it was nothing but shards. No warning, no opportunity to slow down, just BOOM! No thanks.

Do what you will...but don't pretend it is a requirement.
 
Based on comments here and reading done elsewhere, I plan to test to 110% of Vne by slowly working up to it in increments of 5kts to published Vne and 2kts to 110%. Others have been past that (reference the turbo RV6) so I don't expect an issue but will have full gear (chute, etc.) anyway.

Some of the comments in this thread are interesting when juxtaposed with those from the turbo'ed RV6 thread showing operation past the published Vne...
 
Last edited:
ChiefPilot said:
Based on comments here and reading done elsewhere, I plan to test to 110% of Vne by slowly working up to it in increments of 5kts to published Vne and 2kts to 110%. Others have been past that (reference the turbo RV6) so I don't expect an issue but will have full gear (chute, etc.) anyway.

Some of the comments in this thread are interesting when juxtaposed with those from the turbo'ed RV6 thread showing operation past the published Vne...
Click to expand...

Can you please tell me what you have going on here mr chiefpilot
I would like to hear your explanation
Why all the "reference"
What is your obsession with vne and my airplane ????
 
Not for the un-instrumented

In the spectrum of flight testing we do at the Navy, flutter testing remains some of the riskiest. Before an aircraft even flies we do structural modeling and physical shake tests to determine where the resonance peaks are. When it comes time to do Vne/flutter testing, it is done with a fully instrumented aircraft and in most cases the data is telemetered to the ground so lots of engineers who know what they are doing can take a look at the data real time (not to say we don't know what we are doing).

For Vne testing, the control surface in question would be instrumented for strain and position and the aircraft will be trimmed to a slower speed than target so if the stick is released it will pitch up and slow down on its own. Then, at incrementally increasing airspeeds, the control surface is "rung", often by the pilot simply slapping the stick. Engineers will analyze the response of the control surface to determine the damping ratio of the system. As the speeds increases the damping ratio will become smaller. The trending of the damping ratios will be tracked and extrapolated to determine the Vne and the testing will be called off some margin before that speed is reached. This obviously is a simplification, but the process is basicly correct.

Flutter will build energy quickly, so if you go out looking for the actual Vne and it happens to be dictated by flutter and not something else there is a good chance that you won't be able to recover regardless of piloting ability. Personnally, I would make sure my hinges and control runs were as free of slop as possible, verify the balance points of the control surfaces are as recommended, and test it out to Van's suggested Vne (because you know someone has gone there at least once).
 
Good advice.

LotusSeven said:
. Personnally, I would make sure my hinges and control runs were as free of slop as possible, verify the balance points of the control surfaces are as recommended, and test it out to Van's suggested Vne (because you know someone has gone there at least once).
Click to expand...

For some of the newer guys on here, I have a friend, now 82 years old, named Nick Jones, who had his Cassutt F-1 develop aileron flutter at 5,000' in Texas, just before an air race.

The wing self-destructed instantly and he was gyrating to earth at near 300 MPH and couldn't get his three over-the-center latches to release the canopy, so he body-slammed upwards, pulled around 22 rivets and bailed out. His feet were around telephone pole height when the canopy filled!:eek:

Flutter can instantly be disastrous and he still tells this story.

Best,
 
I'm in the middle of phase one testing and I don't have a cool helmet and parachute like Brad so I'm not testing to Vne;), but seriously, I have a question about this. It's not rhetorical.

Let's suppose you take it right to the limit and go to or exceed Vne and your plane doesn't come apart.

What exactly have you just learned?

That you can exceed Vne? How do you know that? Does exceeding it once mean the next time you exceed it you'll have the same outcome? (I'm not an engineer so I can't answer these questions).

And if the value is that it's easy to find yourself in an RV exceeding Vne, what does THAT tell you? Your next encounter with Vne might be 1 knot over, 5 knots over, 10 knots over. Since you don't know you're going to hit Vne accidentally, you don't know how much MORE you're going to exceed Vne by so you don't KNOW what the design is going to allow, do you?

I'll hang up and listen.
 
The truth, from an engineering standpoint , Bob, is that if you exceed the expected or published Vne and nothing bad happens, you have only proved that nothing bad happened THAT time...and not much else. Without additional analysis and examination, you really don't know anything knew except that either the airplane is well and over-designed, or you were lucky. If you flip a coin once, and it comes up heads, does that mean that it will ALWAYS come up heads? No way to know - not enough data.

Engineers build in margin,and often-times, you don't know really know what that margin is. they might guarantee a certain percent - but might secretly build in a little more for their own peace of mind (I have almost made a living trying to guess how much secret margin there is in some aerospace equipment).

To directly address at least one of your good questions, just because you exceeded Vne once without trouble does not mean it will do the same thing next time. You just don't know. Would I worry about a small exceededance in smooth air if you got slowed back down? Probably not. Find yourself 20% over red line in the bumps? I would do a VERY thorough inspection for wrinkles and signs of things like cracked paint.
 
Are we sure that flutter is the primary concern for Vne? Could it be the windscreen? Some other structure limit? Granted, flutter is the scariest but a colapsed windscreen could also ruin your day.
 
Please note Matt's test procedure description in post #25.

Exceeding published VNE while firmly gripping the stick doesn't tell you much. You are an excellent damper. Releasing the stick might show you a surprise. Bumping to excite oscillation is a test.

There is a popular brand of ultralight and light plane kits whose design originally did not include aileron counterbalance. The wing was built around a single large tubular spar, which is not very stiff in torsion. The example I flew would enter a classic torsional flutter mode at 43 MPH if I merely released the stick. Grabbing it for damping and pitching to lose 2 MPH would stop it.

Here's the thing....my buddy the airplane owner had never seen this in 100 hours of flight. His style included a firm stick grip.
 
flyinga said:
Are we sure that flutter is the primary concern for Vne? Could it be the windscreen? Some other structure limit? Granted, flutter is the scariest but a colapsed windscreen could also ruin your day.
Click to expand...

Bingo, that is why I said "[If Vne] happens to be dictated by flutter and not something else". At least none of us (that I know of) has gotten their RV up to sufficient speed to experience localized shocks on the control surfaces ala P-38:rolleyes:
 
LettersFromFlyoverCountry said:
Does exceeding it once mean the next time you exceed it you'll have the same outcome?
As has been stated previously - NO

From an engineering point of view and simplifying a bit, flutter can be modeled as a spring, mass, damper system which needs a forcing function to excite the the oscillatory behavior (2nd order approximation).

the spring (springs generate an opposing force due to displacement) can be accounted for due to material flexibility, actual mechanical spings in the system (aileron trim), hand-on-stick, etc..

The mass is the mass of the surface in question plus all connecting linkages (aileron, elevator, rudder, primer, paint, balance weights, etc..)


the damper (dampers generate an opposing force as a result of velocity) can be accounted for in system friction, hand-on stick, AND the fluid characterisitcs in contact with the surface in question.

The forcing function, in this case a moment about the control surface axis of rotation, is accounted for as the vector sum of all lift, drag and Nz components acting upon the surface.

Each of the necessary elements (spring, mass, damper, forcing function) have components associated with atmospheric condtions - primarily airspeed and density. Also, because the forces acting upon the surface are vector sums (the direction in which the force is acting is important) the machanical alignment of the surface in relation to the airflow is also a factor, therefore Gross Weight, CG (both lateral and longitudinal) are factors as manifested in changes in AOA and mechanical alignment for a given airspeed. Mass and friction in the system can vary from one plane to another because there is no way to ensure conformity between aircraft built in garages.

Therefore when any of the above variables changes the entire system dynamics are affected and results cannot be assumed to remain unchanged - in fact they will be different! You may not be able to perceive the difference with minor changes in any parameter but the system has changed.
Click to expand...
Click to expand...
 
VNE is a safety number not a physical limit

Saying that it is based on TAS and not IAS puts on another layer of safety. The heavily instrumented and monitored Flutter test flight by flight test engineering is for design and requirement satisfaction verification and is not repeated on every production airplane. The design is not in question and you do not have to reverify it on every copy. I can guarantee you that the windshield does not shatter and the structure of an RV-6A with no counterbalance on the rudder of the short tail version does not start shaking at its VNE IAS even though I try to convince my race competition otherwise. If I ever start closing in on 300 kts flutter will be only one of the failure modes I will worry about.

Bob Axsom
 
Exceeding VNE? I am guilty

Most pilots associated with spam can type flying, C-172's, Cherokee's, etc, never really worry much about VNE. In most cases it takes an extreme flight angle for these type aircraft to approach their designed VNE. In my experience some pilots also have a sketchy concept on TAS vs IAS and its meaning to their aircraft. However we who have ventured into the higher performance, especially homebuilt, market need to think about it and maybe 'get real' about it. My 180HP RV-4 cruises at 209 mph true air speed at 8,000' PA. That is just 2 knots under what Van's designed the RV-4 VNE max. Four days ago flying into San Antonio I was descending out of 10,500' PA, which was close to 14,000' density altitude and noted IAS below 180 mph but true airspeed, as measured on my Dynon and verified on my G496 at 227 mph TAS. Yes, well above designed VNE. The air was smooth and I monitored it as I descended and watched where TAS and IAS started to marry up, as it does when we descend...both being equal at sea level and on a standard day. I am admitting this is normal ops for me. Back when I had my Rocket that I bought I would routinely cruise at 190-200 KIAS, with airframe components that are exactly as I have on my RV-4 I built. The Rocket has an accepted higher VNE. When I did my Phase 1 testing with my newly completed and painted and W&B'd RV-4, I did incremental airpseed testing that exceeded published RV-4 VNE to determine the characteristics of my over powered aircraft and finished them knowing my RV-4 did not exhibit negative flying traits at an acceptable limit above published VNE. A 'safe' way to accomplish this testing is another discussion.

In short, if you cruise your RV type aircraft at cross country altitiudes- 10,500 Westbound and 9,500 Eastbound is gnereally where I am, and fly 'full throttle' at those altitudes, generally around 20 in MP, if you lower the nose, you WILL exceed VNE TAS, unless you significantly decrease power setting. It is just a fact. If you are one of those that NEVER exceed Van's posted limit, that is your choice and I'm assuming you understand TAS vs IAS. However, if you consider the 1000's of Vans aircraft flying out there, I am quite comfortable that the aircraft are designed, and if properly built, and verified, can exceed and do exceed published VNE routinely. I chose to test my RV-4 to a limit that I knew I would routinely fly and am comfortable with MY limit.

Not trying to convince anyone out of their opinion, just showing my point of view on it. Flutter, striking other flying objects, unbalanced aircraft etc are all serious business, as is flying in general, but an open mind to the reality of our aircraft and aerodynamics can be liberating.

"A man's gotta know his limitations"
 
Have you thought of entering the AVC Race

Jetj01 said:
Most pilots associated with spam can type flying, C-172's, Cherokee's, etc, never really worry much about VNE. In most cases it takes an extreme flight angle for these type aircraft to approach their designed VNE. In my experience some pilots also have a sketchy concept on TAS vs IAS and its meaning to their aircraft. However we who have ventured into the higher performance, especially homebuilt, market need to think about it and maybe 'get real' about it. My 180HP RV-4 cruises at 209 mph true air speed at 8,000' PA. That is just 2 knots under what Van's designed the RV-4 VNE max. Four days ago flying into San Antonio I was descending out of 10,500' PA, which was close to 14,000' density altitude and noted IAS below 180 mph but true airspeed, as measured on my Dynon and verified on my G496 at 227 mph TAS. Yes, well above designed VNE. The air was smooth and I monitored it as I descended and watched where TAS and IAS started to marry up, as it does when we descend...both being equal at sea level and on a standard day. I am admitting this is normal ops for me. Back when I had my Rocket that I bought I would routinely cruise at 190-200 KIAS, with airframe components that are exactly as I have on my RV-4 I built. The Rocket has an accepted higher VNE. When I did my Phase 1 testing with my newly completed and painted and W&B'd RV-4, I did incremental airpseed testing that exceeded published RV-4 VNE to determine the characteristics of my over powered aircraft and finished them knowing my RV-4 did not exhibit negative flying traits at an acceptable limit above published VNE. A 'safe' way to accomplish this testing is another discussion.

In short, if you cruise your RV type aircraft at cross country altitiudes- 10,500 Westbound and 9,500 Eastbound is gnereally where I am, and fly 'full throttle' at those altitudes, generally around 20 in MP, if you lower the nose, you WILL exceed VNE TAS, unless you significantly decrease power setting. It is just a fact. If you are one of those that NEVER exceed Van's posted limit, that is your choice and I'm assuming you understand TAS vs IAS. However, if you consider the 1000's of Vans aircraft flying out there, I am quite comfortable that the aircraft are designed, and if properly built, and verified, can exceed and do exceed published VNE routinely. I chose to test my RV-4 to a limit that I knew I would routinely fly and am comfortable with MY limit.

Not trying to convince anyone out of their opinion, just showing my point of view on it. Flutter, striking other flying objects, unbalanced aircraft etc are all serious business, as is flying in general, but an open mind to the reality of our aircraft and aerodynamics can be liberating.

"A man's gotta know his limitations"
Click to expand...

Check out www.airventurecuprace.com. Even though today is the last day you can enter and get in the formal printed program, if you use the "Contact Us" button I'll bet Eric Whyte can even get you in there. He said in an email earlier that he is waiting on the mail today before he goes to print - so you two could exchange info today and satisfy that requirement as well.

Bob Axsom
 
This thing called a J-O-B!

Bob,

I have wanted to try this fun type racing ever since I first heard of it but my j-o-b does seem to get in the way of such endeavors! Such as next week I'll be international! But I'm thankful I get to fly for a living so can't complain about said J-O-B and its timing to much! First chance that it all lines up tho, I'm there! Doing the condition inspection on my plane today!
 
flyinga said:
Are we sure that flutter is the primary concern for Vne? Could it be the windscreen? Some other structure limit? Granted, flutter is the scariest but a colapsed windscreen could also ruin your day.
Click to expand...

Pretty sure it's flutter of the tail. From Van's:

Because of the higher Vne, the RV-7/7A MUST HAVE the thicker 0.020" thick elevator and rudder skins AND a counterbalanced rudder. The thinner 0.016" thick skins that are standard on the RV-6/6A, and the older RV-6/6A rudder without the counterbalance, are NOT FOR USE ON THE RV-7/7A.
 
mike in phx said:
Can you please tell me what you have going on here mr chiefpilot
I would like to hear your explanation
Why all the "reference"
What is your obsession with vne and my airplane ????
Click to expand...

I started this thread back when I started putting together the phase one test plan for my project. It has nothing to do with you except that some of the folks have contradictory posts between our two threads.

Since you've had your 6 go faster, what was your plan for expanding the envelope and do you have any data you'd be willing to share?
 
Last edited:
Didnt answer !!!

You did not answer why all the "reference"
What is your obsession with my airplane and vne ????

This is for everybody DONT EXEDE VNE
You only have one chance to get there !!!!

Yes we are getting closer all the time
My personal vne is reached and i have .020 skins on my tail instead of .016
Instead of l shape stiffners they are z shape
One piece wing skins and speedbrakes
These top speeds are only performed in calm wheater
And please there are for sure some one out there like chiefpilot here
Thats going to pick it all apart.
If you dont feel comfortble dont go there
Im for sure not going to slap my stick at these speeds.
Use your head and common sense we are not supermen if we where we didnt need doug reeves and his vaf ( no offense doug )
 
Jetj01 said:
In short, if you cruise your RV type aircraft at cross country altitiudes- 10,500 Westbound and 9,500 Eastbound is gnereally where I am, and fly 'full throttle' at those altitudes, generally around 20 in MP, if you lower the nose, you WILL exceed VNE TAS, unless you significantly decrease power setting. It is just a fact.
Click to expand...

I ran into this last week and was looking for a place to post it. Found this thread via search. I was at 11.5K and decided to descend at about 700 fpm to get under an approaching cloud deck. The IAS inched up as the nose went down but what I did not expect was the redline (autocalculated for TAS by the GRT display) dropping far enough to nearly engulf the entire yellow part of the ASI tape. Redline was hovering at just over 170Kts indicated and I was already doing it. :eek:. Pulled some power back. :(

Thanks to GRT and other EFIS makers for displaying this data. Without it I would have gone way over TAS redline.
 
I'm very embarrassed to admit this, but years ago when I first got my RV 8, and was just learning how to fly it, I didn't realize just how slippery it was. I was in a descent, checked my airspeed and was shocked to see the airspeed needle up against the peg.:eek: The peg was at 240 KTS, so I have no idea how fast I was really going. I chopped the power and gradually-y-y-y-y pulled the nose up. The airplane turned out to be fine. I only admit this and print it, so that some other soul doesn't make the same mistake I made. It's very very easy to go over VNE in a descent in an RV 8 if you don't pay close attention.

( OK everyone out there, make fun of me, I'm ready)
 
donaziza said:
I'm very embarrassed to admit this, but years ago when I first got my RV 8, and was just learning how to fly it, I didn't realize just how slippery it was. I was in a descent, checked my airspeed and was shocked to see the airspeed needle up against the peg.:eek: The peg was at 240 KTS, so I have no idea how fast I was really going. I chopped the power and gradually-y-y-y-y pulled the nose up. The airplane turned out to be fine. I only admit this and print it, so that some other soul doesn't make the same mistake I made. It's very very easy to go over VNE in a descent in an RV 8 if you don't pay close attention.

( OK everyone out there, make fun of me, I'm ready)
Click to expand...

Not going to make fun of you because I did almost the same thing in a -6 :eek:
We were up high (10,000ft or so) and it was a typical hazy summer afternoon around Atlanta--hazy enough that the horizon wasn't distinct and you couldn't really see the ground over the nose, or really at all unless you looked mostly downwards. I'm sure you're familiar with those. Anyway, both of us got distracted for a minute looking at the GPS or something, and eventually noticed that the wind noise was getting really loud. Turns out we were about 30mph past redline and accelerating, in a diving turn. Same recovery--cut power, wings level, graduall pull-up. Several lessons were learned.
 
Lower the nose?

I was taught to pull the power back for descent rather than "lowering the nose". Trim it for the speed you want and no worries about VNE.

Didn't read the entire thread so maybe someone pointed this out.

Would some who use either method please weigh in?

Jerry
 
I've read most of the posts of this thread and have been impressed. I guess it may come with ##s, but you got some smart, experienced people on this board.

One thing I didn't see is a few minor points in Vd testing.

First, Vne is a load choice made by the designer. You run the tests to Vd to verify Vne.

Second, and first significant point, is that only one "mode" is tested at a time. Flutter being an aeroelastic phenomena, causes trouble when things start vibrating in sync (laypersons term) Testing one impulse (stick left; stick back, kick right rudder pedal, ect, one at a time) may catch someone by surprise some day when they're making a descending left turn and have to reverse to the right, all of a sudden.

Third, on test procedure. nose up trim is good, but a better technique, explained to me by John Thorp is to dive to speed "x", put the bird in a shallow climb and when it slows to "X-5mph" then do your impulse. This way, the bird is already slowing down, rather than waiting the approx 1.5 seconds (3/4 for perception and 3/4 sec for reaction) needed to release the control, then the wait for the trim to take effect. If you start low enough (and you should start below Va) you have always flown the bird at the next test speed - until you're "done" that is.

Caca can happen really quick and you want to give yourself all the chances available to stay out of the deep stuff :^)

Onward and upward.

mjb
 
Jerry Cochran said:
I was taught to pull the power back for descent rather than "lowering the nose". Trim it for the speed you want and no worries about VNE.

Didn't read the entire thread so maybe someone pointed this out.

Would some who use either method please weigh in?

Jerry
Click to expand...

In the plane I fly during my day job, we just push the nose down to get the required descent rate. The airspeed jumps initially because of the descent, then will slowly climb more as the engines start to make more power during the descent. Once we get close to the barber pole, then we start to bring the power back to maintain the airspeed and descent rate. In that airplane, the power typically stays at cruise until about 15,000 before power reductions are required.
All we are doing is using power to control airspeed and descent rate make the airplane do what we want.

Unfortunately RVs typically do not have a barber pole easily displaying the IAS limit at altitude, but it would be easy to placard the IAS-TAS limits beside the airspeed indicator.
I imagine you could use the same descent style in an RV. Lower the nose until the aircraft reaches the TAS Vne-5, then reducing power as required to maintain the vertical speed.
 
"The woes of flying with a fixed pitched prop."
Bill;
I fly a fixed pitch prop and a manifold pressure gauge. Initially I was skeptical, but it turns out that Propeller RPM remains nearly unchanged at high speed decent with an inch or three reduction in manifold pressure.
Yet the power delivered and the thrust reduce as desired.
For determining power, I fly RPM in the pattern, and combination RPM/Manifold pressure in transitional flight, but at cruise, I mostly watch the Manifold pressure.
 
You must log in or register to reply here.
Back
Top