Aviation knots
I always use a bowline. will take all you can put on it and undo it without dramas. if you have a tail left on the rope when your finished, a couple of half hitches around the rope finishes it off nicely.
I'vealso tried using a bowline with two half hitches on the other end, and while it is secure, again, I always end up with too much slack in the rope, and you have to spend way to long stuffing around with it to try and get it taught.
I have some mates who can tie a "truckers hitch" - and this one seems to be by far the best i've seen. You can easily adjust the tension on it once the knot is in place - and any pulling force on either end only tightens the knot further. Only problem is I havnt been able to master tying it by myself yet - it is not the easiest knot to learn.
ps stick hard back = stall
pps Stall = loss of lift
pps Stall = loss of lift
Think about the AOA on the ground basically the rigging angle of the particular airframe and if we consider something such as a 150 she needs to achieve 16 degrees to stall, sooooooo logically thinking, she'll go nose up with a stiff breeze, leap into the air, stall once exceeding the 16 AOA and plunge to the ground once gravity exceeds the lift being produced.
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The Truckers Hitch
The truckers hitch has a god and bad history. In Australia our work place safety dept "WOrkcover" outlawed the knot several years back due to a few too many incidents occuring with the knot letting go. Just a heads up on o few $100,000 spent on reasearching the causes of the accident and the actual knot it's self.
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Are we forgetting the tiger is tied down and the tail will never let the wings exceed 16 degrees RAF. Enough defence of what i do already, I am yet to hear your suggestion that is relative. I don't believe (due to the quality of your previous comment) that you realy are so lame as to stand there and shake your head and not offer your advice to my previous question. Please tell me what could be a better solution?
thanks
Ben
edit
I see you have made further comment about the 150 and I may have made a bistake previously with my comment about the AOA. A tiger will sit on the ground with about a critical angle for a 38knot head wind. with that in mind and knowing that we tie down the tiger wing so that they a a little slack ( enough to let the wings rise and exceed the 16 degrees and stall the both top and bottom) and the tail is fastened so that it is unable to rise, we do not encounter the problems you mention above.
You obviously have a good understanding of flying, are you endorsed on tail draggers? if not i can totally understand your previous comments and do not believe you to be lame, still want to hear your suggestion though.
thanks
Ben
edit
I see you have made further comment about the 150 and I may have made a bistake previously with my comment about the AOA. A tiger will sit on the ground with about a critical angle for a 38knot head wind. with that in mind and knowing that we tie down the tiger wing so that they a a little slack ( enough to let the wings rise and exceed the 16 degrees and stall the both top and bottom) and the tail is fastened so that it is unable to rise, we do not encounter the problems you mention above.
You obviously have a good understanding of flying, are you endorsed on tail draggers? if not i can totally understand your previous comments and do not believe you to be lame, still want to hear your suggestion though.
fatboywings
Never flown a Tailwheel, your logic makes sense however if you left the stick in the aft position into a 38kt wind, and for one reason or another you did not tie the tail wheel down immediately or the wings for that matter, the slats open (which you may have forgotten to lock) due to the AOA being close to the critical angle and before you know it............
Interesting logic you apply! from memory with the slats open the ole moth can get close to 23 degrees nose up before a stall............whats the AOA on the ground?
Having said all that, never flown a tail dragger so Ill leave you to it!
Never flown a Tailwheel, your logic makes sense however if you left the stick in the aft position into a 38kt wind, and for one reason or another you did not tie the tail wheel down immediately or the wings for that matter, the slats open (which you may have forgotten to lock) due to the AOA being close to the critical angle and before you know it............
Are we forgetting the tiger is tied down and the tail will never let the wings exceed 16 degrees
ps stick hard back = stall
pps Stall = loss of lift
pps Stall = loss of lift
Having said all that, never flown a tail dragger so Ill leave you to it!
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23 degrees nose up is differant to 23 (or 16 for that matter) degrees to the relative airflow.
Also the aircraft does not come:
rather the centre of pressure moves aft along the mean aerodynamic cord causing a pitch down moment. So using your logic Green Goblin, and based on fatboywings account of the AOA of the Tiger Moth (on the ground), the CoP would be behind the CoG and the 'ol moth' should not be leaping anywhere 
Also the aircraft does not come:
plunge to the ground once gravity exceeds the lift being produced.
What about all the other types that get controls tied full back with the seat beats. Seen a partenavia and lots of piper singles. I suppose if the knot lets go (which is the original question) then you would see how the flight controls would guide the aircraft on its solo flight downwind. I suppose the trick is to tie the aircraft down so the knot does not let go.
p.s. also a big fan of good chocks.
p.s. also a big fan of good chocks.
I worded it wrong, 23 degree AOA on the 'ole moth before a stall. Regardless the COP has to move forward with increasing AOA before it moves aft at the stall.
Also dont forget that a Moth has a swept upper wing and with swept wings the COP moves forward and inboard at the stall causing a pitch up
Also dont forget that a Moth has a swept upper wing and with swept wings the COP moves forward and inboard at the stall causing a pitch up
Bugsmasherdriverandjediknite
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I have some mates who can tie a "truckers hitch" - and this one seems to be by far the best i've seen. You can easily adjust the tension on it once the knot is in place - and any pulling force on either end only tightens the knot further. Only problem is I havnt been able to master tying it by myself yet - it is not the easiest knot to learn.
I personally like a little slack on the rope to let the aircraft wobble about and do its thing in medium winds. never hurts to throw a couple of chocks under the wheels either.
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A tiger will fly quite happily from a stationary three point attitude in a good stiff wind with two persons on board.. I recall some years ago I was maxed out at 1950 rpm watching a squall line approaching the air field that trying to get to in a 15 kt headwind. The line was picking up a lot of dust and was moving very fast from the opposite direction. I arrived over the perimeter fence at about 200 ft when the wind hit and actually the sprog the Tiger and I ceased all forward motion until I dived to ground level and crawled across the field at about walking pace to the grassed area in the centre of the runway triangle where I had about 3 or 4 goes at landing. When I reduced power to try a three point attitude the mongrel thing went about 20 feet in the air and started to go backwards..HMMM… tried a few wheelers, but every time I tried to lower the tail the thing would slide backwards, the skid would stick in the ground and the mains would lift off again, so full noise and back up into the hover. Eventually a few concerned individuals appeared form the hangars and looked like they would assist so I hovered over , settled down between two hangars and chopped the switches as about 20 guys grabbed onto struts and the rear fuselage and anywhere else there was a space and trundled it straight into one of the hangars. Time for ‘tea and medals’.
I do not recommend leaving a Tiger unattended outdoors, regardless of the apparent security of the tie downs. Use 1 inch rope and do a double bowline sheep shank with 222 and a half hitches, the rope and the tie down rings will most likely be there the next day, but not so sure of the Tiger….. still no great loss I suppose, they are a very poor excuse for an aeroplane, though it seems they are highly valued by collectors and enthusiasts (of Tigers that is) and sometimes they are quite a lot of fun, but only sometimes.
I have used some sort of knot that I was taught as a young ag pilot, by another aggie who was also a seaplane/flying boat pilot, don’t know what its called but its halfway between a partial bowline finished with a couple of half hitches, locks tight when under load, but very simple to release, even when wet.
HD
I do not recommend leaving a Tiger unattended outdoors, regardless of the apparent security of the tie downs. Use 1 inch rope and do a double bowline sheep shank with 222 and a half hitches, the rope and the tie down rings will most likely be there the next day, but not so sure of the Tiger….. still no great loss I suppose, they are a very poor excuse for an aeroplane, though it seems they are highly valued by collectors and enthusiasts (of Tigers that is) and sometimes they are quite a lot of fun, but only sometimes.
I have used some sort of knot that I was taught as a young ag pilot, by another aggie who was also a seaplane/flying boat pilot, don’t know what its called but its halfway between a partial bowline finished with a couple of half hitches, locks tight when under load, but very simple to release, even when wet.
HD
What about all the other types that get controls tied full back with the seat beats. Seen a partenavia and lots of piper singles.
My comments were more aimed at something 'light' The moth being a good example, 150 or any LSA type aeroplane.
Thanks HarleyD I love hearing stories such as that!
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HarleyD, I'm repeating this secondhand from a guy who has probably passed on by now, so forgive me for any errors of recollection. He had some wonderful stories about training in Tasmania.
In the early stages of WWII, there was a training base in Western Junction near Launceston. (I don't know how long it stayed operational.) The Tiger Moths would be all over the place when the westerlies would kick in and the base personnel would wait for the phone calls from the various aerodromes the trainees landed. For the aircraft in the circuit, the ground personnel would line up along both sides of the runway and whoever happened to be nearest the aircraft when it was on or near the ground, jumped onto the wing and fuselage to hold it down. Supposedly it wasn't uncommon for the occasional go-round with an extra pax or two.
On the subject of knots, a bowline, a tautline hitch, a trucker's hitch with a half hitch for security on the loop, half hitches, or a combination. They've all worked for me. Never liked the trucker's hitch that much though. It has to stay tight to work properly even with a half hitch on the loop. I like the alpine butterfly knot that Stallie speaks about. Doesn't work so well if you change aircraft though. The knot may have to be undone when tying down a low wing after previously using the rope for a high wing. And Stallie, any firefighter should know how to tie a bowline one handed.
Regarding tying the elevators: I would have thought it more important just locking them in position - any position -rather than have the elevators flap and bang themselves to bits on the stops and stretch the cables. It would seem to me to be far more important than worrying about whether the AoA on the ground was 10 degrees or 110 degrees.
AoA on the ground and a relationship to elevator position? What garbage! So what you're saying The Green Goblin is that if the wings lift off in a high wind, a back stick and a tied down tail is going to encourage additional pitch up? Maybe a slight chance in a nosewheel where the tail has somewhere to go, but a taildragger? If anything, it's keeping the aircraft on the ground.
In the early stages of WWII, there was a training base in Western Junction near Launceston. (I don't know how long it stayed operational.) The Tiger Moths would be all over the place when the westerlies would kick in and the base personnel would wait for the phone calls from the various aerodromes the trainees landed. For the aircraft in the circuit, the ground personnel would line up along both sides of the runway and whoever happened to be nearest the aircraft when it was on or near the ground, jumped onto the wing and fuselage to hold it down. Supposedly it wasn't uncommon for the occasional go-round with an extra pax or two.
On the subject of knots, a bowline, a tautline hitch, a trucker's hitch with a half hitch for security on the loop, half hitches, or a combination. They've all worked for me. Never liked the trucker's hitch that much though. It has to stay tight to work properly even with a half hitch on the loop. I like the alpine butterfly knot that Stallie speaks about. Doesn't work so well if you change aircraft though. The knot may have to be undone when tying down a low wing after previously using the rope for a high wing. And Stallie, any firefighter should know how to tie a bowline one handed.
Regarding tying the elevators: I would have thought it more important just locking them in position - any position -rather than have the elevators flap and bang themselves to bits on the stops and stretch the cables. It would seem to me to be far more important than worrying about whether the AoA on the ground was 10 degrees or 110 degrees.
AoA on the ground and a relationship to elevator position? What garbage! So what you're saying The Green Goblin is that if the wings lift off in a high wind, a back stick and a tied down tail is going to encourage additional pitch up? Maybe a slight chance in a nosewheel where the tail has somewhere to go, but a taildragger? If anything, it's keeping the aircraft on the ground.
Last edited by Lodown; 5th Feb 2009 at 10:53.
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I double up the rope (always recommended for nylon ropes, and safer anyway with hemp or other natural fibre ropes) , loop it through the tie down point, and run two or three half hitches (three for nylon) close to the tie down point after taking out the slack. I do it in such as way as to be able to pull the loose end of the rope so the whole knot disassembles itself, and unties without having to fumble around loosening the knot to get it undone. I put another half hitch for the loose end, so it won't untie itself inadvertently.
If there's a stiff wind expected, a variation on a truckie's hitch can do the job pretty well.
If there's a stiff wind expected, a variation on a truckie's hitch can do the job pretty well.
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Some beaut responses there guys, thanks... very informative! Thanks also Di Vosh and OzBusDriver for the links -excellent!
Bevan666: you raise an interesting point... with a fixed-line tie-down available, how do you prevent your bottom knot (on the fixed line) slipping along the line? Especially if there is no fixed point to attach your own lines?
I wonder if our web-footed compatriots can add anything further to the discussion? Are there particular knots you find useful in the sea-borne world?
Bevan666: you raise an interesting point... with a fixed-line tie-down available, how do you prevent your bottom knot (on the fixed line) slipping along the line? Especially if there is no fixed point to attach your own lines?
I wonder if our web-footed compatriots can add anything further to the discussion? Are there particular knots you find useful in the sea-borne world?
Last edited by RadioSaigon; 5th Feb 2009 at 09:18. Reason: whoops! -spelling muy bad!
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harleyd and lodown,
awesome accounts of times gone by and i hope i never find myself in either stuation, but if so i will know to hover around until 20 guys turn up. Tigermoth flying is a different world and needs to be experienced to be appreciated. I would never leave a tiger unattended over night and don't care for been run over so take special care when flying away.
tie tight and fly right.
kind regards
ben
awesome accounts of times gone by and i hope i never find myself in either stuation, but if so i will know to hover around until 20 guys turn up. Tigermoth flying is a different world and needs to be experienced to be appreciated. I would never leave a tiger unattended over night and don't care for been run over so take special care when flying away.
tie tight and fly right.
kind regards
ben
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We don't use many knots in the traditional manner. We normally splice loops into the end of our lines The Eye Splice as they are very strong and permanent.
All of our floats are fitted with cleats at both ends. We generally secure lines to the aircraft using a cleat hitch The Cleat Hitch.
We use an alpine butterfly on one of the fixed lines on our semi-sub to prevent the aircraft moving either forward or aft with a single rope whilst embarking and disembarking passengers.
If we are using someone elses mooring or picking up from a boat we will often tie a figure eight on the bight Figure Eight on a Bight so that we can hook the loop over the back half of the forward cleat. We can then let the aircraft float back prior to starting the engine. When we start moving forward the loop falls off the back of the cleat - being attached to another boat/mooring prevents us from drifting into something expensive if the engine doesn't start.
The other knot we use is a bowline to secure the loose end of the anchor rode to the float locker to stop us from losing the anchor.
Rope selection and care is very important. Nylon is excellent as it is very strong and stretches under load. 12mm nylon has a breaking strain of 2940kg compared to only 1260kg for the same sized silver rope. Keep rope out of the sun, dry and away from chemicals to prevent deterioration.
A bare (web) footed pilot.
All of our floats are fitted with cleats at both ends. We generally secure lines to the aircraft using a cleat hitch The Cleat Hitch.
We use an alpine butterfly on one of the fixed lines on our semi-sub to prevent the aircraft moving either forward or aft with a single rope whilst embarking and disembarking passengers.
If we are using someone elses mooring or picking up from a boat we will often tie a figure eight on the bight Figure Eight on a Bight so that we can hook the loop over the back half of the forward cleat. We can then let the aircraft float back prior to starting the engine. When we start moving forward the loop falls off the back of the cleat - being attached to another boat/mooring prevents us from drifting into something expensive if the engine doesn't start.
The other knot we use is a bowline to secure the loose end of the anchor rode to the float locker to stop us from losing the anchor.
Rope selection and care is very important. Nylon is excellent as it is very strong and stretches under load. 12mm nylon has a breaking strain of 2940kg compared to only 1260kg for the same sized silver rope. Keep rope out of the sun, dry and away from chemicals to prevent deterioration.
A bare (web) footed pilot.
