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  #1  
Old 06-15-2022, 05:29 PM
sblack sblack is offline
 
Join Date: Dec 2009
Location: Montreal
Posts: 1,603
Default Pickup for crotch strap

Do you guys put the crotch strap pickup point on the front of the spar or the aft side of the spar. Also, is there any place for a crotch strap attachment in the back? It’s not obvious to me, but I don’t have the seats in yet.

Any pictures would be great.
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Old school simple VFR RV 4, O-320, wood prop, MGL iEfis Lite
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  #2  
Old 06-15-2022, 05:49 PM
abwaldal@gmail.com abwaldal@gmail.com is online now
 
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Location: Battle Ground WA
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Might be good to know what model of plane you are working on. Art
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  #3  
Old 06-15-2022, 05:56 PM
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PaulvS PaulvS is offline
 
Join Date: Aug 2019
Location: Western Australia
Posts: 1,136
Default RV-4

Quote:
Originally Posted by abwaldal@gmail.com View Post
Might be good to know what model of plane you are working on. Art
RV-4, per the model specific forum.

I don't know the specifics of that installation but have just installed the crotch strap brackets in a -6 and the attach point is about 2 inches behind the opening for the control stick.
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Paul vS (yes I'm also a Van)
Building RV-6A #22320 O-320 FP. Wings and tail complete, fuselage almost done, working on canopy.
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  #4  
Old 06-15-2022, 06:18 PM
Taltruda Taltruda is offline
 
Join Date: Oct 2017
Location: Las Vegas, NV
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Following, as I want to put in the 5th point on my -4 also. Did you make your own pickup point? And if so, what material is it made from? Did you install the passenger 5th point by wrapping out around the flap weldment?
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  #5  
Old 06-15-2022, 06:43 PM
David Paule David Paule is online now
 
Join Date: Dec 2009
Location: Boulder, CO
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My plane is an RV-3B, not a -4, and I had no idea what angle the strap would make to the mount. But I did have a length of honking big piano hinge. This was taken before I added rivets to those empty holes.



Dave
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  #6  
Old 06-15-2022, 07:56 PM
sblack sblack is offline
 
Join Date: Dec 2009
Location: Montreal
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Quote:
Originally Posted by Taltruda View Post
Following, as I want to put in the 5th point on my -4 also. Did you make your own pickup point? And if so, what material is it made from? Did you install the passenger 5th point by wrapping out around the flap weldment?
I plan to use stainless the same thickness as the other harness hardware (since I have no plating capability) and I will polish it. Just gotta figure out where to bolt it. I really don’t see any obvious place for the passenger. I don’t think the flap torque tube is a great option. I’m hoping someone will post pictures of a tried and true installation.
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  #7  
Old 06-16-2022, 01:14 AM
Taltruda Taltruda is offline
 
Join Date: Oct 2017
Location: Las Vegas, NV
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Quote:
Originally Posted by David Paule View Post
My plane is an RV-3B, not a -4, and I had no idea what angle the strap would make to the mount. But I did have a length of honking big piano hinge. This was taken before I added rivets to those empty holes.



Dave
David, Not sure what the -3 planes show for the elevator push-pull heim joint (rod end) under the seat, but the -8 and I believe all the others show a an365 Nylock nut, not a castle nut. The reason being that the joint can get torqued and the rotation happens at the ball, not at the bolt.
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  #8  
Old 06-16-2022, 03:40 AM
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PaulvS PaulvS is offline
 
Join Date: Aug 2019
Location: Western Australia
Posts: 1,136
Default SBS crotch strap anchor

Hopefully someone will come along with something tried and tested in a -4. In the meantime, here is a photo of the Vans-supplied anchor (OP-24) in a -6. The two bracket halves are made from .032 2024-T3 and are blind riveted below the seat pan with a total of 20 LP4-3 rivets. The crotch belt attach slides between the bracket halves and is held by an AN5 bolt and there is a slot in the seat pan for the webbing to fit through.
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  #9  
Old 06-16-2022, 04:53 AM
Larry DeCamp Larry DeCamp is offline
 
Join Date: Apr 2010
Location: Clinton, Indiana
Posts: 1,247
Default RV 4 specific obseration

I had planned to mount a steel plate behind the spar on the two top, inner most 3/8 bolts through the heavy steel doubler supplied buy Van. This may not be rear enough for you as the belt manufacture suggestion is slightly to the rear of the crotch. The RV6 pic is a good option, but on the RV4, it would require disconnecting the crotch strap to get the floor up to access the aileron pushrod bellcrank heims.

For the rear, I guestimated where the average crotch would be. Fabricated a heavy aluminum angle from the same stock used for the fuel tank forward mounting brackets. Then installed rivnuts on the flanges for AN3 bolts into the flange of the floor pan ribs. You could use the RV6 pic approach here as well. The plans say to pop rivet the floor on anyway😗
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  #10  
Old 06-16-2022, 05:58 AM
Freemasm Freemasm is online now
 
Join Date: Nov 2017
Location: Orlando
Posts: 761
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Quote:
Originally Posted by Taltruda View Post
David, Not sure what the -3 planes show for the elevator push-pull heim joint (rod end) under the seat, but the -8 and I believe all the others show a an365 Nylock nut, not a castle nut. The reason being that the joint can get torqued and the rotation happens at the ball, not at the bolt.
Not wishing to start a debate and sorry for adding to the drift. As long as the castel nut is pinned, it is at least as good as the self locking nut. That's what their design intent was for; application where a fastener could be subject to rotation. Not unusual for a debate here. I'd guess that a majority of the certified world still specs castellated nuts for applications with (rod end) bearings. If I were to apply such in an area that I couldn't relatively easily inspect/service, I'd probably go castel as well despite the drawing. If all of the cards lined up against you and a lot of time/cycles were involved, the bearing could seize subject the bolt to rotation. Odds are long but they still get beaten.
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