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  #1  
Old 03-15-2010, 08:47 PM
JerryG150's Avatar
JerryG150 JerryG150 is offline
 
Join Date: Nov 2006
Location: Bradenton, Florida
Posts: 348
Default Stabilator Cable

Could someone who has not yet installed the stabilator cables let me know the number of threads on the end of the stabilator cables where they attach to the barrel turnbuckles (short cable as well as the long cable ... same or different and # of threads). Mind are already secured and I want to be sure I have a good enough "bite" into the barrel turnbuckel so I won't have to remove them and reinstall them deeper into the turnbuckle. Thanks.
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  #2  
Old 03-16-2010, 07:00 AM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 2,858
Default Turnbuckle tension

The plans specify that not more than 3 threads should be exposed. I assume that specification assures adequate byte. The turnbuckle should be tightened additionally to achieve 40 pounds of tension as measured with a cable tensiometer.
Joe
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  #3  
Old 03-16-2010, 07:23 AM
JohnF JohnF is offline
 
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Posts: 458
Default cable tension

I don't have the plans at hand, but as I recall the cable tension is called for to be 30 to 40 lbs as measured with a tensionmeter...am I not correct?
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  #4  
Old 03-16-2010, 07:53 AM
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JerryG150 JerryG150 is offline
 
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Location: Bradenton, Florida
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Default tension

I didn't start the turnbuckel evenly enough so one side has more threads showing than the other side. I used the tension meter and I have the correct tension.

When my friend installed his turnbuckel so only 3 threads showed on each side it was so tight the forward bulkhead where the front of the cables attach to the pulley system caused that bulkhead to pull inward approx. 1/4" and he was unable to screw in access panel until he removed the locks and made adjustments.

So since I'm not convinced 3 threads showing is "entirely correct" and I hope I don't have to remove the locks and start over, the thread count on the cable end of the cable in an uninstalled (au natural) state would allow me to compute #of threads inserted into turnbuckel.

I'm not certain if I can reconcile 3 threads with correct tension reading ... if not correct tension would win with adequate bite.

I'll probably have to remove the locks and turnbuckels and start again ... just hoping I won't since the scabs on my chubby hands are just forming and I hate to scrape them off before they are entirely healed. Ouch.
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  #5  
Old 03-16-2010, 07:54 AM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 2,858
Default 32-14 Step 4

I went out the garage to double check. The plans say between 35 to 45 pounds on page 32-14 Step 4. I have not locked mine in place yet, waiting to borrow a tensiometer. I stuck a drill bit through the barrel to use as a "wrench" and have two threads showing right now. I used a piece of paper for a feeler gauge to make sure the control stick did not contact its stop before the stabilator control horn contacted its stop.
Joe
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  #6  
Old 03-16-2010, 09:56 AM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
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Default Cable Tension

JerryG150,
After reading your post, I checked the vertical bulkhead under the passenger's knees and sure enough, the bulkhead was pulled aft by 1/8". Luckily it sprung back into position when I loosened the turnbuckles. Since I had the turnbuckles loose, I took one of them apart to get measurements for you. Now my hands are all bloody too. Does that make us blood brothers? LOL
9/16" of the cable ends are threaded 1/4 x 28. There are about 15 threads total.
I used the fish scale to pull the control stick bearing bracket aft. Somewhere between 15 to 20 pounds deflected the bulkhead about 1/16". That can not equate directly to cable tension because of the component geometry. What we need is a BULKHEAD-DEFLECTION to CABLE-TENSION conversion chart. LOL It seems to me that if the cable tension is set with the F-1227 control-stick cover off, then then cable tension will increase when the cover is installed and pulls the bulkhead back into position.
Does anyone know how much the bulkhead under the passenger knees is pulled aft when the stabilator cables are properly tensioned?
Joe

Last edited by Mich48041 : 03-16-2010 at 10:00 AM. Reason: Corrected typos
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  #7  
Old 03-18-2010, 08:56 AM
GDS GDS is offline
 
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Location: Big Bear lake, CA
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Default

We had the same problems, in the end, I tensioned the cables with the cover part in place over the bulkhead. 30-40 lbs measured with the tensiometer worked great. If you over-tension the cables, I don't think you could pull the bulkhead back into position with the cover plate fasteners. When finished correctly, the cables might seem kind of loose and the stick is smoooth.
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  #8  
Old 03-26-2010, 12:09 PM
Mich48041 Mich48041 is offline
 
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Location: Riley TWP MI
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Default Short cable

I learned that Van's intends to post a service bulletin that requires the F-1227 Seat Ramp Cover to be in place when the stabilator tension is adjusted. If the cover is not in place, a bulkhead will be bent. Then if one manages to somehow get the cover back on, the cable tension will increase by a factor of 2 or more, thus over stressing the control system.
In my case, even with the Seat Ramp Cover in place and tension set at maximum, there are 6 threads showing on each end of one of the turnbuckles (3 on the other turnbuckle). After setting the tension, I removed the Seat Ramp Cover and noticed that the under-knee bulkhead was pulled back 1/32". If yours is pulled back much more than that, perhaps your cable tensiometer needs to be calibrated.
I called Van's Aircraft about the issue of more than 3 threads showing on each end of the turnbuckle. The first guy that I talked with would not stick his neck out and say that 6 threads showing was good enough, although he did say that if the length of engaged threads was greater than the diameter of the rod, then it should be OK. He also said that the cable supplier is allowed a tolerance of plus or minus 1/8". The F-1247B long cable should be 124" and the F-1247A short cable should be 33.75", as measured from rod end to center of eye. I recommend that the cables be measured before installation. An easy way to do that is to lay the cable on top of a tape measure, align the center of the eye up with the 10 inch mark, and then subtract 10" from the mark under the end of the rod. The cables can then be paired up so that the total length of the two upper cables equals that of the two lower cables. Or if a cable length is out of spec, then it can be replaced before installation. One of my F-1247A cables is 1/8" shorter than 33.75". Although that is within (barely) the manufacture's spec, it is part of the reason that there are 6 threads showing instead of 3. I called Van's a second time and was told that 6 threads showing was good enough. He is probably right, but I told him that I would feel more comfortable with a longer cable. He agreed to send me one. Unfortunately, Van's does not sort the cables by length. I may or may not get a longer one.
If Van's is listening, I suggest that the cables be sorted so that each customer can receive a matched set of the correct length. The time spent sorting cables will be more than made up for by not having to answer phone calls concerning cable problems. Fewer problems mean happier customers and more business.
Joe
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  #9  
Old 03-26-2010, 05:41 PM
vernhendershott vernhendershott is offline
 
Join Date: Dec 2007
Location: Spruce Creek, FL
Posts: 370
Default

Hi Joe,

Cables need to be measured while under tension so it will be necessary to pin one end and attach a weight to the other end to get an accurate measurement of the cable length. Perhaps someone else can find the reference to how much weight for each diameter of cable.

Best regards,
Vern
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  #10  
Old 03-26-2010, 06:13 PM
Mark Henderson Mark Henderson is offline
 
Join Date: Oct 2008
Location: Napa, Calif
Posts: 274
Default

Joe, is each cable + or - 1/8"? If so, that could be a real issue. I just installed mine and I have 3 threads on one, and 4 on the other showing. This is , however, with the ramp cover off. I have yet to try it with the cover on. I have a few things to double check before I button everything up. One issue with the ramp cover on is how to confirm that the stick hits it's stop before the stabilator hits its stop.
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