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05-20-2011, 08:42 AM
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Join Date: Jan 2009
Location: Denver, CO
Posts: 590
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Quote:
Originally Posted by David-aviator
There was a time when new pilots were specially cautioned about the first 300 hours after training.
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Excellent point, there is a great book called "The Killing Zone", which talks specifically about the first 300 hrs in a pilot's career, and how dangerous it can be to the unaware. I am in this category, at least regarding flight time, much like the pilot in this incident. Its a great book and I recommend it to all new pilots...or even experience pilots.
__________________
Ron Duren
Mechanical Engineer
"SportAir PhD"-RV Assembly/Composites/Electrical
Denver, CO (KBJC)
RV-7 'Tip Up'
Flying!! as of 3/16/14
IO-375/ WW 200G-CS/ SkyView/ Dual P-mags
N531R "Wablosa" Wings of Red
http://www.ronsrv7project.blogspot.com
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05-20-2011, 09:32 AM
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Join Date: Nov 2005
Location: KRTS
Posts: 1,798
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Quote:
Originally Posted by aarvig
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
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I think his point was not that, you should ignore balancing the controls, but that if this individual had stayed within the performance margins of his a/c (and his capability) he would have stayed safe. The point the safety report pulled out was that IF the controls were balanced... he may have survived as the flutter speed would have been pushed further outside of Vne.
This didn't fully understand exactly the performance demands he was asking of his a/c to do what he was trying to do with the camera. Pulling lead or pure pursuit while keeping his speed up, whatever the lead was doing, would require more from him. I can explain those details in another thread if need be. I won't say that his inexperience was a contributing factor, but a lack of understanding... which I know for a fact a lot of high time pilots don't understand either.
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Next?, TBD
IAR-823, SOLD
RV-8, SOLD
RV-7, SOLD
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05-20-2011, 10:09 AM
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Join Date: Mar 2005
Posts: 5,685
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Consider strength & counter balance rudder design
The counterbalance was never found but it is known to have separated from the rest of the rudder. The top of the rudder is not supported at the extreme upper end and the counterbalance horn is cantilevered off of the top of it. It is possible that it is more vulnerable to being ripped off with no flutter when subjected to excessive velocity than the well fared rudder with no cantilevered balance horn (air load and strength issue rather than flutter).
Bob Axsom
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05-20-2011, 11:07 AM
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Join Date: Apr 2006
Location: Ottawa , Canada
Posts: 224
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Quote:
Originally Posted by Bob Axsom
The counterbalance was never found but it is known to have separated from the rest of the rudder. The top of the rudder is not supported at the extreme upper end and the counterbalance horn is cantilevered off of the top of it. It is possible that it is more vulnerable to being ripped off with no flutter when subjected to excessive velocity than the well fared rudder with no cantilevered balance horn (air load and strength issue rather than flutter).
Bob Axsom
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Hmm.
The aerodynamic load of the horn, even if we give it a Cl of 1.0 when deflected fully to the stop (which is very generous for that shape) will only generate about 30kg of force ahead of its attach point (at 125 m/s).... The structure there would support that load.
That being said, the mass of the counterbalance, accelerated and decelerated in a flutter mode will generate considerably more load about that attach point, which is supported by the tearing of the top half of the rudder.
I dont think we need to be concerned about the horn design.
__________________
Chris Hepburn
Ottawa, ON
RV-8 C-GOGO FLYING
Renew 12/20
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05-20-2011, 01:45 PM
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Join Date: Jan 2005
Location: St. Paul, MN.
Posts: 4,792
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Quote:
Originally Posted by Bavafa
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.
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I believe I did consult Van's at one point and if I recall correctly the answer was something along the lines of, "Are you ever going to fly that thing?" Bet nobody can figure out who said that.
I would be curious how people balance these things after painting. The emp tip attachment precludes getting access to the lead weight.
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05-20-2011, 02:01 PM
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Join Date: Jun 2006
Location: 8I3
Posts: 3,564
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Quote:
Originally Posted by Bob Collins
The emp tip attachment precludes getting access to the lead weight.
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Exactly why I use #4 screws/nutplates for tip attachment. Over the years I got some hangar rash that would have been easy to fix had I had used screws on my -6 elevator tips. Balance them slightly heavy during construction, then once its painted pop the tip off and drill a few holes in the counterweight to get them to balance.
__________________
Please don't PM me! Email only!
Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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05-21-2011, 12:09 AM
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Join Date: Oct 2007
Location: Sacramento, CA
Posts: 3,351
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Quote:
Originally Posted by Bob Collins
I would be curious how people balance these things after painting. The emp tip attachment precludes getting access to the lead weight.
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There are many ways of doing it, one easy way is to proactively, during construction, install one or two nut plate in the tooling hole of the elevator, next to the original weight. If any weight needs to be added then it can be bolted on there.
Quote:
Originally Posted by rocketbob
Balance them slightly heavy during construction, then once its painted pop the tip off and drill a few holes in the counterweight to get them to balance.
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I did just that, only to find out that after painting my trailing edge was heavy. I had to add about 5.5 oz to make it balanced. A removable tip is another good way to go about doing it.
__________________
Mehrdad
N825SM RV7A - IO360M1B - SOLD
N825MS RV14A - IO390 - Flying
Dues paid
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05-21-2011, 05:15 AM
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Join Date: Feb 2006
Location: Anywhere, USA
Posts: 1,132
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Guys,
Borrowed this from Rockets web site.
Know your speeds. RV-7A
VNE--230 MPH------Exceeded by 32KTs or 37 MPH
VA----Exceeded 140 MPH
Great article. Great read.
On November 12, 2001, American Airlines Flight 587, crashed shortly after takeoff from New York?s John F. Kennedy International Airport. The crash killed all 260 people aboard and 5 people on the ground. The National Transportation Safety Board (NTSB) determined ?the probable cause of this accident was the in-flight separation of the vertical stabilizer as a result of the loads beyond ultimate design loads that were created by the first officer?s unnecessary and excessive rudder pedal inputs.? As a result of this accident and subsequent investigation, it was revealed that many pilots have a misunderstanding of what the design maneuvering velocity (speed), VA, represents. Many pilots believe that as long as the airplane is at or below this maneuvering speed, they can make any control inputs they desire without any risk of harm to the airplane. This is not true.
The design maneuvering speed (VA) is the speed below which you can move a single flight control, one time, to its full deflection, for one axis of airplane rotation only (pitch, roll or yaw), in smooth air, without risk of damage to the airplane. Even though the accident discussed above is a part 25 airplane, VA is applicable to part 23, CAR 3, and LSA airplanes. Also, even though experimental airplanes may not have a published VA , they will still have some maximum maneuvering speed associated with the maximum structural design loads. Therefore, the pilot should be aware of what speed this is, and adhere to the guidance herein. The regulations governing the design strength requirements for airplane structure require adequate strength for full control deflection (below VA). However, they do not require the manufacturer to make the airplane strong enough to withstand full control input followed by a full control input in the opposite direction, even below VA. Neither do they require the manufacturer to design the airplane for more than one simultaneous full control input such as full ailerons with full elevator and/or rudder.
VA, as published in the airplane flight manual (AFM) or pilot?s operating handbook (POH), is valid for operation at the gross weight stated, which is typically at max gross weight. It is especially important to note that VA decreases as the airplane weight decreases. At first, this may seem counter intuitive. All pilots understand that when the airplane is subjected to an external force, such as the 2 aerodynamic force from a control surface, the airplane responds by accelerating (rotational acceleration) about one of the airplane?s axes. This was stated many years ago in Newton?s Second Law of Motion. The law states that when an object of mass ?m? is acted upon by a force ?F?, it will undergo acceleration ?a? in the same direction as the force. More simply stated in the widely known equation ?F = ma?, which can be rewritten as ?a = F/m?. Rewritten this way, it is clear for a given control force ?F?, as the airplane weight ?m? decrezses then the acceleration ?a? will increase. This higher acceleration gives rise to higher loads on the airplane structure. Therefore, as the airplane weight decreases, the allowable maneuvering speed must also decrease, to ensure that the airframe is not damaged. Pilots may remember from their written exam that VA-NEW = VA √ (WNEW/WMAX-GROSS) as the way to calculate the corrected (new) maneuvering speed due to operating at a weight less than the maximum gross weight. NOTE: This formula is for calculating the VA change about the pitch axis; however, it can be used for all axes.
Recommendations
The FAA wants to clarify that operators should know what the maneuvering speed is and to caution pilots on what to avoid by adhering to the information described above and contained in the regulations. We recommend the following for maneuvering at, or even below, VA:
DO NOT apply a full deflection of a control, followed immediately by a full deflection in the
opposite direction.
DO NOT apply full multiple control inputs simultaneously; i.e., pitch, roll and yaw
simultaneously, or in any combination thereof, even if you are below VA.
Reduce VA when operating below gross weight, using the following formula:
VA-NEW = VA √ (WNEW/WMAX-GROSS)
For Further Information Contact
Mark James, Aerospace Engineer, 901 Locust, Room 301, Kansas City, MO 64106;
phone: (816) 329-4137; fax: (816) 329-4090; email: mark.james@faa.gov.
__________________
Bruce (BOOMER) Pauley
Kathy (KAT) Pauley
RV 7A--"MISS MARIE"--- N177WD (SOLD FLYING)72742
VAF #582-----------------EAA LIFETIME MEMBER
EX -KC-135A -------------BOOM OPERATOR #3633
VAN'S FLIGHT------------#6930
See you in OSHKOSH
http://www.mykitlog.com/users/index....ley&project=84
=VAF= 2006-2020 DUES PAID
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05-21-2011, 03:05 PM
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Join Date: Sep 2010
Location: Sao Paulo, Brasil
Posts: 72
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Quote:
Originally Posted by LifeofReiley
Guys and Gals,
This paint... balance is BS !!! Fly by Van's numbers and everything will be fine balanced/painted or NOT. 
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Just a question of good, healty sense! The Yellow arc on analog Airspeed Indicators was an eye opener, red arc was reason for panic! NEVER Exceed Velocity - VNE.
Maibe this pilot wasn't quite adaptet to the EFIS.
Also I think that 234 Knots on a little RV 7A isn't quite reasonable!
There where a lot of slick retractables coming apart and loosing their (V)tails in inadvertent dives before.
Just respect your envelope and nothing will hurt you. As simple as that.
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05-21-2011, 03:21 PM
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Join Date: Mar 2006
Location: Newport, TN
Posts: 7,496
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My EFIS also has color coded strips beside the ASI...
Quote:
Originally Posted by bignose
Just a question of good, healty sense! The Yellow arc on analog Airspeed Indicators was an eye opener, red arc was reason for panic! NEVER Exceed Velocity - VNE.
Maibe this pilot wasn't quite adaptet to the EFIS.
Also I think that 234 Knots on a little RV 7A isn't quite reasonable!
There where a lot of slick retractables coming apart and loosing their (V)tails in inadvertent dives before.
Just respect your envelope and nothing will hurt you. As simple as that.
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