[delusional]

now that we have the stall warning, why not some proper Skylane-style tie-down rings? Retractable, I mean.

Anybody know if this is feasible or already done it?

 

[N941WR]

You would need to add some structure to support the retractable tie down rings.

The Van's rings are simple and light. The doublers Van's includes in the kits supports the aileron bell cranks, provides a place to screw in the tie down ring, and is a hard point for jacking.

I'm thinking Cessna could learn something from Van's.

 

[airguy]

I'm thinking Cessna could learn something from Van's.

HAHAHAHA!!! That's putting it mildly!

 

[rocketbob]

now that we have the stall warning, why not some proper Skylane-style tie-down rings? Retractable, I mean.

Anybody know if this is feasible or already done it?

Yes it is feasible. I've always thought that a more outboard location for the tiedown rings would provide advantages that would work better than the current location that attaches to the spar strips.

 

[Greg Arehart]

My tiedowns are already "retractable" - I simply unscrew them when I'm ready to fly. No fuss, no muss.

greg

 

[roee]

Devils advocate

I'm thinking Cessna could learn something from Van's.

HAHAHAHA!!! That's putting it mildly!

I agree with that general sentiment. HOWEVER, Van's tie down design does leave some to be desired.

Mechanically it is crude, as the base of the tie down ring sits against unsupported skin (there's an air gap between the skin and the threaded mount) and the skin will distort if the tie down ring is tightened down. And there is just barely not enough gap between the skin and the mount for a jam nut, so in practice this means that the tie down rings can't be tightened down properly.

Aerodynamically it is also crude, as the rings sit out there in the breeze and make drag. I don't know how much, or how significant it might be in the bigger picture. But as obsessed as the RV community is with drag reduction, it's surprising that this particular instance generally goes unnoticed.

My tiedowns are already "retractable" - I simply unscrew them when I'm ready to fly. No fuss, no muss.

One could consider the tie down rings removable by unscrewing them, but that's only good for perhaps a few hundred cycles before the threads in the aluminum mounts will be toast, and they won't be easy to replace. So unscrewing them is reasonable to do for an occasional long trip or air race, but probably not something you want to do for every flight.

Not trying to be overly critical, but yes, there is still room for improvement. And that's a good thing. It means that someone here can take the initiative and come up with a better solution. And I haven't seen the tie downs on a 182 so I can't comment on them specifically, but yes, on a few rare occasions Van's could even learn something from --gasp!-- Cessna.

 

[arffguy]

retractable tie-down rings

Yeah, I have seen it done on an RV. No, I don't know the innards of the wings and I can't find my photos of the external view yet. I can tell you, after years of working in the FBO business, that the springs on many Cessnas were frequently broke and the things would not retract properly anyway.

 

[rvmills]

Yes it is feasible. I've always thought that a more outboard location for the tiedown rings would provide advantages that would work better than the current location that attaches to the spar strips.

With ya there Bob...have been pretty close to my pitot tube a couple times with tie-down chains. I'm wonderin' if the location was chosen as a point of max-strength (and min-damage potential) on the wing to mount the tie-down.

My tiedowns are already "retractable" - I simply unscrew them when I'm ready to fly. No fuss, no muss.

Aerodynamically it is also crude, as the rings sit out there in the breeze and make drag. I don't know how much, or how significant it might be in the bigger picture. But as obsessed as the RV community is with drag reduction, it's surprising that this particular instance generally goes unnoticed.

One could consider the tie down rings removable by unscrewing them, but that's only good for perhaps a few hundred cycles before the threads in the aluminum mounts will be toast, and they won't be easy to replace. So unscrewing them is reasonable to do for an occasional long trip or air race, but probably not something you want to do for every flight.

I was thinking along the same lines as Greg...but mine only go in when I need them (X-C and need to tie down, etc). Not sure if that is the norm or the exception for the fleet, or somewhere in between. Concur with the drag-averse nature of the community (as it should be!)...and dern it, I forgot to tape the those two holes before the last race!

It's been a pretty low percentage usage item though (in my case), so hopefully the threads will last a good long time (hadn't considered that...hmmm, I better be careful! )

It's an interesting idea though to be sure. Like replacing the ring mounts though, might be a tough chore in a completed airplane. Cool to think about though!

Cheers,
Bob

 

[Bubblehead]

One good thing about Van's tie downs

One thing I like about the standard Van's tie downs is that you can back them out a little to put the pull of the tie down rope in line with the eye of the ring. The ring is stronger in that direction than if the pull were from the side.

What I like is also what I don't like. You cannot screw the ring down tight to the skin so the shoulder helps reduce the bending moment at the threads.

On the Cessna system, the high wing and wide distance between the tie downs allows the tie down ropes to pull almost straight down on the retractable "blade." I've tied my RV-8 down at a lot of airports and the low and short wing with tie downs relatively closely spaced is a disadvantage because the pull from the tie down ropes is almost always at a flat angle that puts a lot of bending moment on the tie down rings.

I would like a retractable blade if it were oriented properly to the direction of the tie down ropes. I'm not sure that can be reliably done because of the variations in the spacing of tie down ropes at airports.

 

[Crossbow]

My tiedowns are already "retractable" - I simply unscrew them when I'm ready to fly. No fuss, no muss.

greg

Thanks! I was thinking about the same thing myself.

 

[N941WR]

...Mechanically it is crude, as the base of the tie down ring sits against unsupported skin (there's an air gap between the skin and the threaded mount) and the skin will distort if the tie down ring is tightened down. And there is just barely not enough gap between the skin and the mount for a jam nut, so in practice this means that the tie down rings can't be tightened down properly...

You mean I shouldn't have enlarged the hole enough to screw the ring all the in? When doing this I figured there would be little difference between a small hole and a hole large enough to put the ring all the way in.

...One could consider the tie down rings removable by unscrewing them, but that's only good for perhaps a few hundred cycles before the threads in the aluminum mounts will be toast, and they won't be easy to replace. So unscrewing them is reasonable to do for an occasional long trip or air race, but probably not something you want to do for every flight...

I think the issue is that most people keep their planes in a hangar and they are not tied down. Thus the rings are only installed when traveling and tied down outside, which isn't that often (for most of us).

I did see one RV where the owner has left the steel rings in the aluminum fitting and they were being eaten up by the dissimilar corrosion. Thus I never leave mine in except when tying the plane down. Besides, I'm afraid I would drop one on someone's head while flying.

 

[Ironflight]

If you have an RV-8, you even have a place to store the rings when they aren't installed in the wings - there are threaded holes in the baggage compartment gussets just for storing the rings! And mine live there 99.9999% of the time. I never fly with them in the wing - they are installed for the rare case of tieing down, and removed again before flight. In fact, mine are coated with Red Plasti-Dip to remind me that they are a "Remove Before Flight" item for me....

Paul

 

[tomwebster]

This discussion brings up a question:

The line folks at Winston=Salem have
a policy of not using the exhaust to
ground an airplane for refueling.
I screwed in a tie-down ring for them
to ground my RV-7A for service.

My question:
Is there any other good grounding point
available on our planes?

Tom

 

[breister]

Just for comparison's sake, the smaller Lancairs use removable tie down attachments that are simplicity itself. Don't know where they are sourced from, but they WORK like these:

except the T-handle IS the loop (imagine the picture below with a button inside the loop):

Makes it really handy if the ropes are tight - just push the button, then work on the knot somewhere more convenient with no tension.

 

[David Clifford]

When I built the Cozy MKIV, one mod I did was for a simple retractable tie-down ring that pivoted on one of the wing mounting bolts. I made it of SS although aluminum would do. Basically it was made from 1/8" X 1-1/2" X 3" stock. The left end had a 1/2" hole tucked up in a radiused corner for the rope and access material was removed form that end. The pivot hole was in the center and the right end just had radiused corners. The bottom of the wing had a slot that the rope end of the tie down could drop through. The weight of the right end keeps the tiedown up in the wing during flight, you have to use a key or anything slim to poke the right end up into the wing and the rope hole end pivots down through the bottom of the wing. This could easily be adapted to the RV wings. If it were not so difficult to post pics on this site I would do it.

 

[Ron Lee]

Seldom use the tie-downs? Reality

I use the tie-downs almost every trip someplace. I go to breakfast...I use the tie-downs. Go to lunch...use tie-downs.

It just takes minutes to secure the plane.

 

[roee]

You mean I shouldn't have enlarged the hole enough to screw the ring all the in? When doing this I figured there would be little difference between a small hole and a hole large enough to put the ring all the way in.

Yeah, I think that's a good idea. I would have probably done the same, except mine is a QB so it was too late.

 

[roee]

I think the issue is that most people keep their planes in a hangar and they are not tied down. Thus the rings are only installed when traveling and tied down outside, which isn't that often (for most of us).

I use the tie-downs almost every trip someplace. I go to breakfast...I use the tie-downs. Go to lunch...use tie-downs.

It just takes minutes to secure the plane.

Right. The airplane would be hangared at the home airport, but generally tied down at a $100 hamburger or just about any other destination. So the tie downs do get used quite a bit, at least for me.

 

[Ron Lee]

I did see one RV where the owner has left the steel rings in the aluminum fitting and they were being eaten up by the dissimilar corrosion.

So what anti-dissimilar metal corrosion goo should I use on the tie-down threads?

 

[Pilottonny]

Machined eye bolts!

I have a design for a real slick tie down ring in my head, but I have to get to it, to have it made by a machine shop. Obviously I would like Titanium, but for $$$ sake I will probably accept Stainless.

The rings will be very small, just large enough to accept an Aluminium Carabiner (the type used by mountain climbers) If it works out the way I think, I may have a couple of hundred made and put them up for sale on VAF.

Regards, Tonny.