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Tail tie down weight

dhmoose

Well Known Member
How much weight does it take to hold the tail down when jacking the airplane up? Obviously, more is better (or an eyelet built into the floor is even better), but what should I shoot to exceed? 100lbs? 200lbs?
Thanks,
David
 
Tail Weight

Use a large washtub full of water, or a series of 5 gallon buckets of water ganged together
 
my son, 2 years ago -!

seemed a tie-down strap under his butt, attachec to the tail ring......and a little wiggling, presto the nosewheel levitated just enough to remove the yoke & get a block under it.
... so he was aboot 137.5 lbs then, plus pizza, minus the fuel in the mains. ...cowl was off...toolboxes on the wing pretty much at c.g. eh?
 
If I want to unweight the nose wheel on my completed -10, I need 200lbs hanging from the tail tie down bolt.

Jim Berry
RV-10
 
Good stuff

I appreciate the help from everyone I asked the question while approaching the Home Depot aviation aisle in the hopes of buying the right amount of concrete for the job. I ended up buying 6, 60 lb bags of Quikrete for $15 (just add water type concrete), an 18 gallon bucket ($9), 3 castering wheels ($20), a ratcheting tie down strap ($10), and an eyelet ($5). Upon entering the shop, I sat my 180lb butt on the tail and I was only able to get the nose wheel up if I bounced a bit (and the prop wasn't on yet). So, I installed the wheels, used 4 bags of the concrete which filled the 18 gallon bucket, and buried the anchors of my eyelet in the setting concrete. I think it'll come in at near 300lbs which should be plenty to pull the tail down.

Who knew you'd be mixing concrete on your aircraft project! Never a dull moment!

David
 
A friend of mine who built a Lancair propjet had to make a tie-down so he could jack the wings up and do retract tests. I stole his idea, modified slightly, so I could make a tie-down to keep the nosewheel on the ground until I am ready to mount an engine. I bought a trash can with wheel dolly at Home Aviation Depot, along with a couple of large eyebolts with large washers and nuts. I already had the concrete bags (from back when I was building the RV-6A!). I mixed up 3 bags in the bottom of the trash can (wheel dolly attached; this one has a nice molded one that locks on). Then I drilled for the bolts just above the level of the cement and inserted them with washers and nuts. The washers are to sandwich the hole you drilled; if you can't get eyebolts threaded up to the eye, it's Ok, the washers alone will be suffcient; they just keep concrete from leaking out. I used bolts 180 degrees apart but nothing says you can't add more. Once the bolts are in, I mixed the remaining 3 bags and poured it in. Once the concrete set, I cut off the top of the trash can using a cutoff wheel.

FP14062012A0001I.jpg


If you were keeping count, I used 6 bags which is only 360 pounds, somewhat less than the weight of an IO540. But it works as a compromise because 1) the gear mounts are aft of CG and 2) more concrete would have made the unit too tall to go under the gear leg. I can always add additional weight (as I have done in the picture) as needed (and I keep a stand under the tail just in case). The unit can also double as a tail tie-down, is on rollers so it can be easily moved or blocked in place if I don't want it to move, and can be lifted and the rollers removed if I REALLY don't want it to move. It was quick to make (even the setup time was only about a day) and not prohibitively expensive - though I admit I didn't pick the cheapest trash can available.
 
With my prop on, it takes about my body weight 225# to get it up in the air. But even at that it doesn't take much tugging to pull the nose back down on the front end.

I used a concrete anchor in the garage floor and it's worked great. I left the nose picked up for 3 months while working on various tasks.
 
How do you let it down after it is up

Resurrecting this old thread.
I understand the concept of raising the nose by pulling down the tail with a ratcheting strap. And I am using six 5 gallon jugs of water as my weight. To test the concept I added tension to the strap and was able to pull the nose up. I only went as far and pulling most of the weight off the nose. However, when I went to release the strap, it releases all at once and the nose drops rather quickly. Glad the nose wheel wasn't up off the ground. So how are you releasing the strap? Should I just add my body wight to the tail and then release?
 
Resurrecting this old thread.
I understand the concept of raising the nose by pulling down the tail with a ratcheting strap. And I am using six 5 gallon jugs of water as my weight. To test the concept I added tension to the strap and was able to pull the nose up. I only went as far and pulling most of the weight off the nose. However, when I went to release the strap, it releases all at once and the nose drops rather quickly. Glad the nose wheel wasn't up off the ground. So how are you releasing the strap? Should I just add my body wight to the tail and then release?

A 1.5 Ton Aluminum floor jack from HF fits nicely under the spindle of the front nose gear. It has worked well for most nose lifting tasks - checking breakout force, tire/wheel servicing, lifting onto scale, etc. In your case you could use it to let down the nose in a controlled manner.

Like so....

dp3QxpzwL_B7eg9elTPKtRQTed-QaxV7CDMywpqZ6REmmzNroDGNDrHCcTzziKmxB_jn555ofv35hTnnX41vPx-6FuHyXweRyRgvf-DF3XDQr3G7NkZyTlqbdyDSaxC224BvWUZ7O2D7MRdf0WJuW68PVeZWlVBuFyWxjZP74OQ5WrBgTbtrY9B86WSvIUDBhwRjy4O_UEvbickm67d0ndOD0nzffZIDgS2q9IYiuwjyorqmneinvdU6iPdjPCcEBnSzez138ybDM0JT7Tse0yrWvij6O_oVVWCzlxOyWjDXPVfRypa_UjOWb13kMN_wszv3Cr9eXDmkDJmbMs88lMNUoI33qyEpLEZjGUe-ZgOEFfQRfrweX7oAHN7S4B5Lw30qnbV1puQnfX-ZAKbOenjYKOQi4XieX9uX4-8ukfNUk_tvomRqNGt-5yukgdOb27bMiEkaHM1QoIHGEFmxCUzdt6LZGg8GBnXbgOqJJeUgO6wsM-o7SSHYlAM9LlJJSRHKMnnWM3pI5R4sEgbM4ZnVjz6swBeCVUIri5yXrSI3zFI1lRWzbhT-pt4KU6d8WpROy0qbC3U01H4VXUfTaaPdtoJn4pwMua5ECe8k9OdOOWhNRM8CInkPHDqv7y0MXp1VdcyO-iQvgap8uXv6KtwLHP1Ne2oUQLbm1IZZ1axvFcVMUB8kNc8=w400-h853-no
 
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Nose lift

I installed a 3/8 threaded anchor in the concrete floor directly under the tail tie down. Screw in a tie down and use a come a long to pull the tail down. You can also control it when you lower the nose back down, which is why I don?t use a ratchet strap.
 
Slow...

Resurrecting this old thread.
I understand the concept of raising the nose by pulling down the tail with a ratcheting strap. And I am using six 5 gallon jugs of water as my weight. To test the concept I added tension to the strap and was able to pull the nose up. I only went as far and pulling most of the weight off the nose. However, when I went to release the strap, it releases all at once and the nose drops rather quickly. Glad the nose wheel wasn't up off the ground. So how are you releasing the strap? Should I just add my body wight to the tail and then release?

I use my cars scissor jack to lift the nose wheel off the ground. Once elevated, I then attach the concrete bucket to the tail. With it attached, I lower the scissor jack until the nose wheel hangs freely. The process is reversed which then allows the scissor jack to slowly lower the nose.
 
I use my engine crane to lift the nose using straps connected to the engine mount vs pulling the tail down.
 
How much weight on tail is safe ?

I use a ratcheting winch bolted to a concrete filled container to pull down the tail ring. It takes a LOT of force. Is there any danger of damaging the structure with this method of raising the nose?
 
I use a ratcheting winch bolted to a concrete filled container to pull down the tail ring. It takes a LOT of force. Is there any danger of damaging the structure with this method of raising the nose?

I'll have to put a dynamometer on it next time but I'm betting it's 300lbs or slightly less on a -10. It would be interesting what the mothership says.
 
I use a ratcheting winch bolted to a concrete filled container to pull down the tail ring. It takes a LOT of force. Is there any danger of damaging the structure with this method of raising the nose?

Perhaps you should consider how much you trust the aluminum anchor that you cut the tail tie down threads into.

For me, I would never raise the nose by pulling down on the tail tie down. Lifting the nose up with an engine hoist is simple and safe.

Carl
 
There must be something I'm not following here - how is the pull-down force on the tail to lift the nose any greater than the air load on the horizontal stab/elevator that's required to take off or land on the mains? Are we worried somehow about the fuselage structure not handling that load - or the tail tie-down ring? Off the cuff, neither one would worry me - seems like expected loads that would have been designed for.

But I see Carl's point - and thus far have only ever raised my -10 nose wheel by lifting the engine ring with a hoist. Last night I raised my 6A nose by ratcheting the tail down to the deck of my 60" mower - but that's a welded stainless tie-down ring with two AN-3 bolts in shear holding it on.
 
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Tail Weight

An important distinction here is where the aircraft is supported to get the nose wheel off the ground. If the wings are supported at the jack points under the main spar, then the weight required on the tail tie down isn't much and is comparable to the aerodynamic load on the HS in level flight. If the main gear wheels on the floor are the fulcrum, then it'a a different story since they're well behind the main spar and a long way behind the CG. This requires a lot more weight and probably isn't a great idea...
 
Perhaps you should consider how much you trust the aluminum anchor that you cut the tail tie down threads into.
Carl
Carl's point is that the threads cut into the anchor may not be designed to handle the load.

For the archives, I used 250 pounds of water in six 5 gallon water jugs and it was more than enough weight. It was not the most elegant system, but it was what I had without having to purchase anything.
 
Understand, Paddy, but the mains are also the fulcrum the tail plane is using to hold the nose wheel off for T/O and landing. Evidently that's 250# (or less) of down-force, depending on loading and CG.

Maybe we can get someone to test a tail tie-down fixture to destruction and report the numbers. Sounds like a job for Allan Nimmo at Anti-Splat Aero.
 
HS loading during takeoff

the mains are also the fulcrum the tail plane is using to hold the nose wheel off for T/O and landing. Evidently that's 250# (or less) of down-force, depending on loading and CG.

Not exactly, Bill. By the time the HS has enough authority (from airspeed) to rotate the aircraft about the mains, the majority of the weight is already borne by the wings at the center of lift (near the main spar). The mains don't see much fulcrum load at all in actual fact.
 
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