Swift 16 Shakes

[aramsdell]

This topic has been addressed before and now I think I may have some help for everyone that still has it.
Numerous things have been said and done to help alleviate the, sometimes, violent shaking exhibited by the Swift on spool-up/down.
Taken together the modifications remove most of the problems.
Those mod.'s include the new beefier landing gear, imroved feathering shaft and my own practice of rocking the cyclic controls at those times when shakes appear. All-in-all my Swift still has had some, albeit minor, shakes when on a hard or slippery surface like ice.
I have included a quick diagram of my modification. It is made from suitable used ends of a 3mm flybar. Don't cut off threads as these will help in adjusting and mounting this piece. 2 ends are cut and bent to the shape shown in the diagram. They will be soldered/brazed with one in front of the other where they overlap. Where they do overlap I ground the faces flat with a Dremel tool and grinding wheel. After brazing/soldering, clean it up and paint black. Screw on a 3mm hex nut all the way in on the threads each side. Drill the Boom-strut attachment to 3mm and drill the landing gear tab to 3mm. Push one end of the new brace through the boom-strut then through the L-gear mount. Move to other side and push the boom-strut mount over the rod then push the rod through the l-gear mount point. Center the whole affair and turn the 3 mm nuts out 'til they are just about touching the boom-struts. To make everything nice you should measure the distance between the skids at the FRONT landing gear strut. These skids bend with time on the workbench so you can match the rear to the front. Thread on the 3mm Nyloc nuts on the outside. Adjust the nuts in/out to get the Lnading gear straight.
You'll find this gear much stiffer and the tail will tend to stand higher over time not the opposite.
The landing gear was also boiled to soften it up like we used to do with Props for planks.
See also boil your Nylons post.

[Coolice]

Hey,

My first Swift suffered with the spool down shakes until I done the feathering shaft mod, removing the ball so the spindle could pass though the plastic head ok.
I already grease my head dampers and do so on all my machines, but new fliers may not know this and so this is good practice to allow the dampers to move freely on the spindle and not grab as the rubber grips the metal.

Another trick is to move the boom supports from the U/C to the main mechanics, I have mine mounted high just above where the gyro sits at the rear of the mechanics. I also use the new V3 struts which are slightly shorter and thicker the the previous units, as well I don not run the rear blocks that jack up the tail as unless you fly from very long grass they are not needed.

It has also been noted that blade tightness in the main grips can make a difference to the Swifts spool up/down issues and so check your tightness. I would suggest tighter than looser as it was felt as power is removed after a flight, the blades lag forwards and hence get thrown out of balance.

My machine does not suffer from the shakes with the above done.
Check my gallery to see how my Swift is configured
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[Kamikazi]

I've been fighting with the Swift on/off for several months now trying to calm the "wet dog shake" during spoolup/down. I really don't enjoy flying it much when it does this. My friends with TRex 600's laugh at it and tell me to dump that POS and get a good machine. I admit I've been tempted to do that and just get a Rexx 600.

The blades (Carbons) have been balanced to 2/100th of a gram, lengthwise CG is perfectly matched. The spindle is the new "Enforced" one with the small ball that is a VERY loose fit. Smeared white grease on the ball and the dampers. Thrust bearings are greased and absolutely installed correctly. I have the metal head, and basically all the metal upgrades with the exception of the grips and new tailcase. Flybar and paddles measured with calipers and centered perfectly. I have the newest v3 undercarriage. Everything "feels" silky smooth, which makes the fact that the silly thing persists on shaking wildly even more depressing. I'm moving my boom supports up to the battery tray as I type this, but I don't expect it will help.

One thing I have noticed about the Swift, compared to my other machines, is that the upper part of the frames flexes a LOT when you grab the head and move it from side to side. I have the third bearing block upgrade installed, but it didn't help the shaking and doesn't do a thing for the flexing of the upper frames. I don't think that stiffening the undercarriage further will help with the weakness in the frames.
Some of my other helis have noticeably flexy landing gear, but very stiff frames. (and they don't shake like the Swift)

I'm thinking of adding some cross bracing to the frames directly behind the motor, or perhaps fabricating an open bulkhead that will bolt into the same area.
This should stiffen the upper frames enormously in this area. There is obviously a mechanical resonance somewhere, and the more I look at it, the more I'm thinking that this is where the problem is...
My feelings on this could be completely wrong, but I'm at the point where I'm ready to try anything that hasn't been tried before and sounds reasonable.

[helivaguy]

here is what i did...

I've been fighting with the Swift on/off for several months now trying to calm the "wet dog shake" during spoolup/down. I really don't enjoy flying it much when it does this. My friends with TRex 600's laugh at it and tell me to dump that POS and get a good machine. I admit I've been tempted to do that and just get a Rexx 600.

The blades (Carbons) have been balanced to 2/100th of a gram, lengthwise CG is perfectly matched. The spindle is the new "Enforced" one with the small ball that is a VERY loose fit. Smeared white grease on the ball and the dampers. Thrust bearings are greased and absolutely installed correctly. I have the metal head, and basically all the metal upgrades with the exception of the grips and new tailcase. Flybar and paddles measured with calipers and centered perfectly. I have the newest v3 undercarriage. Everything "feels" silky smooth, which makes the fact that the silly thing persists on shaking wildly even more depressing. I'm moving my boom supports up to the battery tray as I type this, but I don't expect it will help.

One thing I have noticed about the Swift, compared to my other machines, is that the upper part of the frames flexes a LOT when you grab the head and move it from side to side. I have the third bearing block upgrade installed, but it didn't help the shaking and doesn't do a thing for the flexing of the upper frames. I don't think that stiffening the undercarriage further will help with the weakness in the frames.
Some of my other helis have noticeably flexy landing gear, but very stiff frames. (and they don't shake like the Swift)

I'm thinking of adding some cross bracing to the frames directly behind the motor, or perhaps fabricating an open bulkhead that will bolt into the same area.
This should stiffen the upper frames enormously in this area. There is obviously a mechanical resonance somewhere, and the more I look at it, the more I'm thinking that this is where the problem is...
My feelings on this could be completely wrong, but I'm at the point where I'm ready to try anything that hasn't been tried before and sounds reasonable.

[Coolice]

Hey,

The Swift shakes are magnified due to the tall under carriage I'm afraid, I am sure with a shorter still U/C the spool up resonance would dissappear completely.
Having said that I have still seen Swifts which shimmy when others do not do so, indeed my own Swift sometimes wobbles a little more than on other occasions.
I feel it is also due to the main blades leading or lagging on spool up and then their general tightness on spool down, if they are slightly to loose on dropping the power they lag forward slightly and induce a slight out of balance.
Bottom line though once past any resonance the machine is as smooth as silk, well I know mine is and I have not done anything special to mine. I'm not even flying the newer, stronger frames or the 3rd bearing block frames.

One thing I have come across is the upper mast bearing stopper. If it's to tightly pulled against the upper main shaft bearing this can cause problems. I find the slightest up & down play helps and does not cause any problems.

Your friends may laugh at you, but if it all goes wrong with their Trex 600's they would not be laughing so hard I dont think.
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[Coolice]

Your friends may laugh at you, but if it all goes wrong with their Trex 600's they would not be laughing so hard I dont think.
.

Hey All,

It has been brought to my attention that this comment may be taken the wrong way against the Trex600, please do not read it this way.
In no way, shape or form was I trying to put down the Trex600. I am not so shallow to put down another manufacturer.

I made this comment in light of some of the spares prices I had seen compared to the Swifts, but I do not take away the Trex600 is a nice machine with good, solid qualitys. Having actually flown one I can say I was very impressed.

The point I was trying to get across is that there is no need for others to pass judgement when the Swift is just as capable a machine as the Trex, but we also need to remember that we cannot compare a Swift 16 (30 class) to a Trex600 (50 class). Unless we look at the Swift 550.
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[Kamikazi]

That was one reason I went with the Swift vs. waiting for the TRex 600 at the time. I knew that the Century parts prices were going to be lower. I wanted a machine that I could push myself with and not be as afraid of crashing when trying new stuff.
I also have a Predator Gasser, and to be honest, I worry about repair parts prices and also the time it takes to do the repairs if I smash it up.
For that reason, I tend to fly it a little more conservatively.
The Swift seemed like a capable 3D machine that wouldn't break the bank or require a lot of work to get flying again when I do crash it.

That doesn't mean I might not buy a TRex 600 later on, but for now, the Swift seems better suited to what I want. Once airborne, it definitely flys great. It just doesn't like being on the ground :wink:

[aramsdell]

Best mod. I've done. Use Raptor 50 landing gear. Use stock Swift skids and rear spacers. If I had longer 3mm bolts I would jack the tail and front back up. The tail is lower to the ground so you must be more careful in several ways.
Don't spoolup quick and spin it on the ground, you snap the tail skid. Don't plant the blades on an auto etc.
I made my own aluminum tail skid and it bends when I do the above.
Bad points out of the way. I haven't broken them yet and this includes way worse autos than the Swift gear could handle. While I am getting a lot of practice and getting better there is the occasional drop from several feet and the 'bounce'. They take it! They are wider too and I've only tipped over twice- no damage.
The shakes are nearly invisible. The secret IS good balancing of course but the Swift gear just let's minor imperfections shine! These are shorter and thicker so resonance doesn't happen as easily. I may never use the spare Swift gear I have....Guess I'll have to crash bad for that.

[aramsdell]

2 .

[aramsdell]

It ios now 1-25-08 and I haven't broken the original Raptor 50 gear ! 1 Brand new set of Swift struts for sale ....

I think the heli would smash before I could break the gear.

[philiusm]

I've got two Swifts both with Raptor 30/50 landing gear. One shakes on spool down, one doesn't. For me it's all down to uneven lag on the blades on spool down caused by the tightness of the main blades in the grips. On the one that shakes I find that tightening the grips so the blades are quite stiff solves the problem. Also the grips have to be equal in tightness otherwise on spool down the blades lag differently and that upsets their balance.

I've just had a thought, I wonder what happens if I leave the blades very loose in the grips whether they would then lag equally and not shake?

Incidentally on the one that shakes I have put a stiffener between the frames just behind the main shaft to try and cure it. It's made from an old motor/bottom block. It's cut short and mounted vertically between the two frames. I had to file a slot in it so that it clears the main shaft. It makes the frames really rigid. If you waggle the head the only thing that flexes is the landing gear. It makes no difference to the spool down shimmy so frame flexing isn't causing it.

Regards,

Phil M

[aramsdell]

Loose blades make for broken tail booms. AUTO-matically. If your blades are very loose then in an auto , when blades are spinning slowly, you can very easily have a boom strike when landing . Try loosening them up, swing one back 45 to 60 degrees and turn head with blade in this position. It can probably touch the tail boom without much pushing. I've lost a few booms andblades this way early on.
Al PS on my radio I have 'direct throttle control' it's a Royal Evo-9. This is a slider that will enable 0 to 100% throttle, whatever you dial in. I use it as a safety on the ground and a rev limiter when testing etc. I go to 0 pitch and then slide to 0 throttle. Lately the shakes haven't been as bad though. I think it is also ground resonance too. Depends on the surface you fly off especially tar or flat stuff.

[philiusm]

I'll keep 'em tight then:-)

Thanks