Thread: tiedown philosophy

Normally we tie a bird down from two spots under the wing and one on the tail. For a tail dragger, this makes perfect sense. For most nosewheel planes, the tail tiedown would keep the plane from weathervaning into a cross-wind. However, for a pod and boom design like the CT, there is very little empenage presented to a cross-wind, which allows us to have those small rudders.

I am thinking of changing how I tie down, using the two wing spots and the nose. That FD tail sleeve would work around two prop blades to hold the nose down. My thinking is that on the CT the risk is that a headwind strong enough to make the plane want to fly would lift the nosewheel, maybe bang the tail on the ground, especially if I am using the seat belt as a control lock to hold the stabilator in the full nose up position. I think that the two wing tiedowns and the nose might be enough to control the limited tendency to weather vane. Any thoughts on this?

WF

I use the nose tie down method ! the 2 wing loops and a strap behind the prop and spinner straight down to a screw in tie down near the front wheel and i lock my controls with a bungee strap round rudder pedals in a full nose down position i wouldn't want my stabilator locked in the up position ...

Mike

Originally Posted by 207WF

Normally we tie a bird down from two spots under the wing and one on the tail. For a tail dragger, this makes perfect sense. For most nosewheel planes, the tail tiedown would keep the plane from weathervaning into a cross-wind. However, for a pod and boom design like the CT, there is very little empenage presented to a cross-wind, which allows us to have those small rudders.

I am thinking of changing how I tie down, using the two wing spots and the nose. That FD tail sleeve would work around two prop blades to hold the nose down. My thinking is that on the CT the risk is that a headwind strong enough to make the plane want to fly would lift the nosewheel, maybe bang the tail on the ground, especially if I am using the seat belt as a control lock to hold the stabilator in the full nose up position. I think that the two wing tiedowns and the nose might be enough to control the limited tendency to weather vane. Any thoughts on this?

WF

the scenario you describe did happen to me. when mammoth airport was closed i parked at lee vinning. i wasn't expecting an 80mph south wind and i did have my belt around the stick. the result was that my ct was flying on the ramp and scraping its fin.

to add to that the lee vinning pumice company supplied an 80mph abbraisive to treat my plexi.

Concur, crosswind is probably more likely than a down blast on the tail surfaces, but I did see the results of a micro burst on a 172's tail feathers and it hurt the bird. Not sure same would happen to the CT with short couple fuse and smaller tail feathers...However, the only question I have would be, where do you find a ramp with tie downs to accomodate or do you park it bass ackwards.. in the typical two wings and tail arrangement....??

The most critical aspect of any tiedown system is that you minimize the angle of attack of the wing…you have to hold the nose down.
Our planes can take 100 knot wind straight on (they do it every flight) but if the tail comes down at that speed (which is above our maneuvering speed) the wing can develop more lift that its structure is designed to handle.
And though we all hope to avoid hurricanes and tornados, most tiedown systems will probably fail at much lower loads than our wing, leaving your plane on its back. At 44 knots, our stall speed with flaps up (you should have your flaps up when tied down… and while taxing too), the plane can come off its wheels. At 62 knots, with the tail down, you may have the equivalent of 1320 lbs dangling from your tie downs (lift = coefficient of lift x Wing Area x .5 x air density x velocity squared).
On the other hand, if you keep the nose low enough (so the coefficient of lift is zero) the wing will not produce any lift at all. The only force you need to worry about then is drag. And even at 100 knots the drag is no greater than the thrust put out by our Rotax. Any tiedown system should be able to hold this drag force just fine.
My tiedown situation is a bit unique. I have a 2004 CT2K which does not have hard points on the wing and Flight Design has not approved a retrofit.
We use the aircraft engine mount (the white metal structure bolted to the fire wall) to tie the nose down. There is a welded crossbar on it that is easily accessible from behind the nose wheel strut. We carry a short loop of high-strength climbing rope with a carabineer on it. We pull into the normal aircraft parking spot backwards, loop the rope over the engine mount, and then clip it to what would normally be the tail wheel anchor. I’ve attached a photo of this arrangement.
If I was expecting really strong winds I would shorten this loop so it pulls straight down. If I was expecting a hurricane or tornado (and couldn’t get out of town) I’d take the nose wheel off and set the front fork on the ground, maintaining a slightly negative angle of attack on the wing to help hold the plane down.

Thank you for the expanded explanation. Very informative. Do you still tie the wings down with your suggested configuration and if so does it take long ropes to reach backwards to their tiedown points since the plane is in the parking space backwards with nose tied down to the ramps tail tiedown point?

Mike (Koerner)

Don't you use 'wing loop' has mentionned by Micromike on a previous post.
My 'early' 2005 doesn't have neither the wings ring mount and came with straps to be 'looped' around the wings
Micromike
Do you pass the loop between the ailerons and wing or behind the ailerons ?

CharlieTango, did you do anything to polish your plexi? Just wondering what to do for eventual scratch removal on my CTSW plexi surfaces?

Use a bungee from one rudder pedal to the other via the stick (instead of the seat belt) and a head wind will tend to hold the nose down (low angle of attack). Also, a tail wind may raise the nose wheel some, but that would spoil lift on the wing.

I have polished two CT windshields with this kit. One was my own windshield. I also did my Honda Goldwing motorcycle windshield.

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I have and still use this polish by hand every few times to maintane the windshield. I have been using T210 polish and windshield cleaner for about 7 years. I use the 210 windshield spray to just wipe off the bugs and keep the static down. There are of course many windshield cleaners now days.


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These are from aircraft Spruce.