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POSTING RULES

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10-03-2013, 08:15 AM
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Join Date: Oct 2005
Location: Estes Park, CO
Posts: 3,947
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Antisplat
Quote:
Originally Posted by aarvig
Allan, I appreciate all your innovations and talent. I also appreciate the way you bring them to the forum. I think it is professional and in no way trying to scare people into buying stuff. For crying out loud people...if you don't like what he is selling, don't buy it. I for one feel he is the only one out there addressing known issues with these aircraft with simple fixes that help improve your odds. When my plane is at the correct stages Allan, I will be a customer.
To all the naysayers...IF YOU HAVE A BETTER IDEA, GET TO THE DRAWING BOARD YOURSELVES AND START MAKING PARTS.
Allan has a right to offer what he has for sale on this forum without getting harrassed out of here.
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Make that two.
I plan to put them on my 7a as well.
__________________
Larry Larson
Estes Park, CO
http://wirejockrv7a.blogspot.com
wirejock at yahoo dot com
Donated 12/03/2019, plus a little extra.
RV-7A #73391, N511RV reserved (2,000+ hours)
HS SB, empennage, tanks, wings, fuse, working finishing kit
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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10-03-2013, 09:36 PM
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Join Date: Dec 2007
Location: Beverly NJ
Posts: 17
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Tail Feathers and nose gear mod
I have just installed the nose gear mod on my 7A.Did a couple of take off landings before reinstalling fairings and wheel pants. Every thing looks good so far. How ever after inspecting my elevator and ruder I have found no cracks or any problems. I,ve had my plane at red line a few times. Been flying it since 2005. Just been to the Bahamas and back. I also have found some rod end nuts loose which I have now tightened. But no cracks at all everything looks good. Question why don't I have cracks think about it flying eight years. Also the balance on my elevator is forward I asked Vans they said ok if a little forward . Its been looped rolled flown at red line #no cracks no flutter. I think your nose mod takes care of a real problem not so sure about the tail failure thing being a vans weak design. Look on utube some sevens have been put through some extreme arobatics. But I will keep paying attention to any new info.
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10-05-2013, 05:01 PM
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Join Date: Oct 2005
Posts: 58
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If we are seeing crack growth in fastener holes in the tail attach doubler area mentioned, it can be caused by several things. First, there could have been small manufacturing (e.g. builder) defects in one or more of the fastener holes. Normal cyclic loading could then produce a crack that grows at a certain rate based on the cyclic loads spectrum. (refer to durability and damage analysis DATA methodologies) The crack growth rate can be fast if the doubler was designed for less loads than are actually being encountered. This happens a lot. Often the remedy is to re-design the doubler to accommodate the real loads. However, this often drives the problem to other adjacent areas, because the loads they are subjected to also exceeds their design loads. As a result, they start failing.
I would not recommend putting a beefed up doubler in this area without a more complete engineering analysis. You can make things a lot worse. In a former life I was chief of structural engineering on the A-10A, and A-7 fighter fleets and dealt with these kinds of problems routinely.
__________________
Doug Kronemeyer
N972DK
RV-8A
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10-05-2013, 10:09 PM
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Join Date: Apr 2012
Location: West Fargo, ND
Posts: 1,073
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Quote:
Originally Posted by ferret
If we are seeing crack growth in fastener holes in the tail attach doubler area mentioned, it can be caused by several things. First, there could have been small manufacturing (e.g. builder) defects in one or more of the fastener holes. Normal cyclic loading could then produce a crack that grows at a certain rate based on the cyclic loads spectrum. (refer to durability and damage analysis DATA methodologies) The crack growth rate can be fast if the doubler was designed for less loads than are actually being encountered. This happens a lot. Often the remedy is to re-design the doubler to accommodate the real loads. However, this often drives the problem to other adjacent areas, because the loads they are subjected to also exceeds their design loads. As a result, they start failing.
I would not recommend putting a beefed up doubler in this area without a more complete engineering analysis. You can make things a lot worse. In a former life I was chief of structural engineering on the A-10A, and A-7 fighter fleets and dealt with these kinds of problems routinely.
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This more simply put is a case of what I commonly refer to as "Sausage Management". You know; squeeze on one end and it just comes out the other  .
Truthfully, this was my first though when installing the doubler plate at the vert stab. I certainly don't want to induce higher loading into an adjacent area not intended for those loads. The up side is there are no attachment holes adjacent that could start a crack.
__________________
Derek Hoeschen
EAA Tech Counselor
RV-9A #92103 - N803DK
G3X, Superior XO-320, Dual Pmags, Catto 3B
www.mykitlog.com/dbro172/
1974 Bellanca Super Viking - N16AW - Flying
RV-8 #83565 - N184DK - building
1968 Mooney M20C - N6801N - Sold
1956 C-182 - N744W - Sold
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10-06-2013, 11:40 AM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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The Vans-supplied part is not a doubler, but rather an attach plate connecting the vertical stabilizer spar to the horizontal stabilizer spar and fuselage. The Splat parts are stiff stainless steel doublers, by nature much stiffer than any aluminum doubler...but I digress.
I'll suggest it is possible to improve the fatigue performance of the aluminum attach plate without a significant change in stress distribution.
(1) add a 1/4" or so edge distance on each side
(2) straighten the outline to eliminate the large scale notch on each side
(3) ensure good edge finishing
(4) in a retrofit hole the locations are known, so eliminate the slots.
(Base photo credit to Bruce Hill, from an old thread)
__________________
Dan Horton
RV-8 SS
Barrett IO-390
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10-06-2013, 01:37 PM
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Join Date: Jan 2005
Location: KASH
Posts: 498
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Quote:
Originally Posted by ferret
I would not recommend putting a beefed up doubler in this area without a more complete engineering analysis.
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This is the best advice to come out of this thread...thanks Doug!
__________________
Dave Setser
RV-7 N701ED FLYING!
Nashua, NH (KASH)
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01-24-2017, 01:02 PM
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Join Date: May 2012
Location: Ga
Posts: 662
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Reviving this thread, wondering if any of the resident engineers have possibly done some analysis on the stainless doublers for the forward vertical attach point?
Thanks,
Quote:
Originally Posted by ferret
If we are seeing crack growth in fastener holes in the tail attach doubler area mentioned, it can be caused by several things. First, there could have been small manufacturing (e.g. builder) defects in one or more of the fastener holes. Normal cyclic loading could then produce a crack that grows at a certain rate based on the cyclic loads spectrum. (refer to durability and damage analysis DATA methodologies) The crack growth rate can be fast if the doubler was designed for less loads than are actually being encountered. This happens a lot. Often the remedy is to re-design the doubler to accommodate the real loads. However, this often drives the problem to other adjacent areas, because the loads they are subjected to also exceeds their design loads. As a result, they start failing.
I would not recommend putting a beefed up doubler in this area without a more complete engineering analysis. You can make things a lot worse. In a former life I was chief of structural engineering on the A-10A, and A-7 fighter fleets and dealt with these kinds of problems routinely.
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__________________
Craig
RV-3 Sold
RV-4 Sold
RV-6a Sold
RV-9 IO-360 CS, Built and Flying
Aerostar 600A, Family Hotrod
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01-24-2017, 02:18 PM
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Join Date: Sep 2010
Location: Redlands, Ca.
Posts: 1,458
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Guarantees!
....We currently have about 650 of this mod installed, many with considerable hours of service. No reported ill effects, and best of all, no departed tail feathers. Regardless of ones ability to accept, or admit the fact that a known issue of cracking is taking place in this area. The fact remains, it is happening, and we have received many e-mails and calls from customers who found this crack when they went to install the mod. If you feel this is not for you, then don't take advantage of its availability. Someone made a statement to the effect that "you can make things worse". I don't agree. Very difficult to make things much worse than the tail leaving in flight. That event in not survivable, and this mod will definitely do what it was intended to do, and nothing else. I assure you, should they find myself, my aircraft, or any aircraft, with this mod properly installed in a smoking hole. The tail will be in there, and these brackets will be in tact, doing their job. Thanks, Allan... 
__________________
Allan Nimmo
AntiSplatAero.com
Innovative Aircraft Safety
Products, Tools & ServicesInfo@AntiSplatAero.com Southern California (KREI)
RV-9A / Edge-540 
(909) 824-1020
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01-24-2017, 02:24 PM
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Join Date: May 2012
Location: Ga
Posts: 662
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Tip toe
Allan,
My question was only seeking input from an engineer who may have looked at this particular mod or area and did said analysis as a previous poster recommended. I do not have any issues with your products and I understand what you are trying to accomplish. Please do not take my asking the question as being negative. I just wanted to hear feedback, if there was any, on analysis by an engineer. Sorry if I came across another way.
Quote:
Originally Posted by PerfTech
....We currently have about 650 of this mod installed, many with considerable hours of service. No reported ill effects, and best of all, no departed tail feathers. Regardless of ones ability to accept, or admit the fact that a known issue of cracking is taking place in this area. The fact remains, it is happening, and we have received many e-mails and calls from customers who found this crack when they went to install the mod. If you feel this is not for you, then don't take advantage of its availability. Someone made a statement to the effect that "you can make things worse". I don't agree. Very difficult to make things much worse than the tail leaving in flight. That event in not survivable, and this mod will definitely do what it was intended to do, and nothing else. I assure you, should they find myself, my aircraft, or any aircraft, with this mod properly installed in a smoking hole. The tail will be in there, and these brackets will be in tact, doing their job. Thanks, Allan... 
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__________________
Craig
RV-3 Sold
RV-4 Sold
RV-6a Sold
RV-9 IO-360 CS, Built and Flying
Aerostar 600A, Family Hotrod
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01-24-2017, 03:14 PM
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Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
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Quote:
Originally Posted by PerfTech
....We currently have about 650 of this mod installed, many with considerable hours of service. No reported ill effects, and best of all, no departed tail feathers. Regardless of ones ability to accept, or admit the fact that a known issue of cracking is taking place in this area. The fact remains, it is happening, and we have received many e-mails and calls from customers who found this crack when they went to install the mod. If you feel this is not for you, then don't take advantage of its availability. Someone made a statement to the effect that "you can make things worse". I don't agree. Very difficult to make things much worse than the tail leaving in flight. That event in not survivable, and this mod will definitely do what it was intended to do, and nothing else. I assure you, should they find myself, my aircraft, or any aircraft, with this mod properly installed in a smoking hole. The tail will be in there, and these brackets will be in tact, doing their job. Thanks, Allan... 
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When just a bit of the info smells bad, it makes me inclined to assume that the entire thing is rotten.......
If as many people as you imply have actually found cracks, have, Van's would be hearing about it.
It is not something that has been reported.
This type of marketing is shameful.
You are implying that if the few RV's that have had accidents in which some type of failure of the emp. was involved, that the accident wouldn't have happened if your parts had been installed.
Anyone can read the accident reports. From them it is easy to see that a failure or lack of strength in the vertical stab. fwd spar attach area was not even remotely considered to be a cause.
Hopefully moderators wont delete this for vendor bashing because it is not.
It is calling attention to shameful marketing strategy being used here (and it is not the first time).
__________________
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.
Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
Last edited by rvbuilder2002 : 01-24-2017 at 03:18 PM.
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