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06-27-2010, 10:44 PM
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Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
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Quote:
Originally Posted by JohnF
This is likely the root of my stalled incident.
I have been communicating with EAA Tech Counsler, Larry Geiger, and I have concluded based on his information, and his experiment with the trim method I used, that the sudden pitch up that resulted in a stall was my fault.
I made the mistake of thinking that mid-way between full up and full down of the nose of the stabilator would be a neutral, in-flight position. It is not.
By having what was believed to be a 'bit' of "up" trim, there was apparently a large up trim, and upon reaching takeoff speed the system gave me what I had unknowingly asked for.
Marty just posted a good explanation of setting the trim so the indicator is placed where you should avoid my mistake.
I still have not had the FAA visit. Today I placed an order with Vans for the material I need to repair the plane...nothing technically difficult, just a lot of work. Experts that I worked with regarding the engine convince me that the gear box should be sent to a Rotax service center for checking, and that it probably wouldn't be necessary to tear down the engine, just do a dial out check. I will pull the engine to replace the lower firewall and some other sheet metal.
I hope to be in the air by fall. Thanks to all for your input. I hope this confession of fault on my part will help another builder.
JohnF
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John,
I do not know who the experts are that are advising you, but thought I would comment that I think their advice is not correct, and is specifically contrary to the recommendations made by Rotax in their documentation.
You have described the flight as being very short and still in takeoff mode. Because of this I am assuming you never had a chance to close the throttle, so I am assuming the engine was still at full throttle at propeller to ground contact. Because of this there is a strong possibility that the engine had an over-speed as it shed the prop blades. Maybe you already know that the engine stopped right away when the prop hit but it would be a good idea to double check the stored data on the D-180 to see what it did.
If it did have an over-speed, depending on the severity there is potential for internal damage.
__________________
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 ")
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06-28-2010, 07:58 AM
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Join Date: Apr 2008
Location: Davenport, IA
Posts: 1,390
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Quote:
Originally Posted by Mel
This is exactly why I tried to get Van's to publish the control deflection specifications. This kind of problem could be avoided.
I think that had John known that the "up" travel is much greater than "down" travel, it may have gotten his attention and caused him to investigate further.
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And....... Nor the plans or the Dynon installation manual tells the builder where to set the take-off trim bar on the trim indicator. The plans could be improved here.
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06-28-2010, 08:59 AM
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Join Date: Apr 2008
Location: Riley TWP MI
Posts: 3,070
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Thanks to JohnF
I want to thank John for sharing his accident with everyone and possibly saving others from the same fate. If it happened to me, I would have been tempted to hide the airplane in the hanger and, if anyone saw it, say that the wife backed into it with the car. LOL
And thanks to Marty for explaining how to set the trim setting for takeoff. Without knowing any better, I would have set it to the center of adjustment. I witnessed my friend's first RV-12 flight and thought that he might stall on takeoff because the plane leaped off the runway and climbed steeply at first. But he got the nose down and everything was OK.
I agree with Marty that Van's should make the takeoff trim setting clear before others experience an unexpected steep climb on takeoff.
Joe
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06-28-2010, 09:01 AM
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Join Date: Aug 2008
Location: Texas, Fort Worth
Posts: 1,237
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Takeoff trim setting
Since all RV12 E-LSAs are going to be very close in the finished product I agree with Marty. A picture of the Approximate Takeoff trim position should be added to the directions, Maybe in the Production Acceptance Procedures.
John
RV12 N1212K
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06-28-2010, 09:07 AM
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Join Date: Nov 2009
Location: Independence, OR
Posts: 316
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John,
I agree with Scott. I don't mean to imply that an engine tear down is required but it may be. Rotax manuals discuss overspeeds and prop strikes and spell out what needs to be done for different scenarios.
I don't mean to add to the problems you already have but you need to be sure that the engine is good to go when you fly again.
I was very glad to hear that you are OK and want to thank you for sharing.
__________________
John Horn (donated for 2020)
Independence, OR
LSRM-A, CFII
Rotax Service, Maintenance, and Heavy Maintenance Trained
Building an RV-12, N7878H reserved
Flying a Flight Design CTSW
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06-28-2010, 10:52 AM
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Join Date: Mar 2007
Location: Sonoma County
Posts: 3,821
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Quote:
Originally Posted by Mich48041
I witnessed my friend's first RV-12 flight and thought that he might stall on takeoff because the plane leaped off the runway and climbed steeply at first. But he got the nose down and everything was OK.
I agree with Marty that Van's should make the takeoff trim setting clear before others experience an unexpected steep climb on takeoff.
Joe
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Fly the nose wheel first and the plane will tell you what it needs...............
This is a nose wheel RV. Unless Van's changed procedures, the stick should be full aft for take off. No matter where the trim is, the nose will lift and your job is to hold it just off of the ground. If it is out of trim, you will know it right now and compensate for it with pressure on the stick. Now you can trim the plane after you establish your climb.
I always trim nose down for take off and landing. If I relax the stick, I want the nose to drop.
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06-28-2010, 08:39 PM
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Join Date: Jun 2009
Location: Dayton, OH
Posts: 838
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Thanks, John
thanks for all the up-front information and analysis. I haven't gotten into setting the trims yet, but it sure does look like we could use more information from Van's on exactly what the tail positions should be and just what the servo settings should be. I've been concerned for 8 months about just where "neutral" is. Now I wish I's taken more photos.
Wayne 120241
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06-28-2010, 08:54 PM
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Join Date: Apr 2005
Location: KSLC
Posts: 4,021
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Quote:
Originally Posted by gasman
Fly the nose wheel first and the plane will tell you what it needs...............
This is a nose wheel RV. Unless Van's changed procedures, the stick should be full aft for take off. No matter where the trim is, the nose will lift and your job is to hold it just off of the ground. If it is out of trim, you will know it right now and compensate for it with pressure on the stick. Now you can trim the plane after you establish your climb.
I always trim nose down for take off and landing. If I relax the stick, I want the nose to drop.
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I fly the 6A the same way. I know exactly what the nose wants to do, as airspeed picks up. I'm also trimmed nose down for landing, and never change it before takeoff.
L.Adamson
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12-15-2010, 04:49 PM
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Join Date: Jun 2010
Location: Okeechobee, FL
Posts: 14
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Initial Trim Takeoff Setting
It would seem like the initial Trim takeoff setting should be set at the neutral position. In other words the position that you would use for level flight. At least that is what I did in my RV7.
I would normally set this for a first flight by first leveling the stabilator, ( a level on the stabilator spar) to the flight level position. Then I would adjust the trim to be equal to the stab tips.
Any comments?
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12-15-2010, 05:47 PM
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Join Date: Apr 2008
Location: Davenport, IA
Posts: 1,390
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See the 4th post in this thread. It explains where I set the take-off position bar on the trim indicator.
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