slider head

[Gyro Jim]

Any body have a picture of Erine's or other slider head? Do they work well? Thanks gyro jim

[Alan_Cheatham]

Sliders work but are best used, if not absolutely necessary, for stiffer masts and are less, if non-effective, on an already flexible mast.

Various pictures from various places.

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[WHY]

Gyro JIm

Good question Jim, because on a tractor if a pylon is used and not "shock mounted" it will be very stiff.

Tony

[Gyro Jim]

I see how it works, thanks for photos Alan.

[GyroCFI]

I'm a little fuzzy on the concept of the slider head, from the pictures it appears that the head is free to "slide" on the steel barrel, what does that gain and what is the purpose of the slider?

[Alan_Cheatham]

The slider de-tunes the mast from the rotor to reduce two-per-rev shake.

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[GyroCFI]

Got it, thanks Alan. Is anyone making them as a retrofit to any of the existing heads?

[swfarrier]

So then, other than guessing, what are the factors needed to know if a mast is too stiff or flexible? Are we talking length of mast or thickness of mast or a doubling of the masts (side by side using thinner wall tubing) ? It would be a little better to figure these things logically in advance rather than 'whistling after you pass the graveyard', so to speak. Also, a little history of developement would help us all to understand more completely the reasoning behind using them and by the way, how many gyrocopters out there actually have one of these installed. The ones installed---was this after a non sliding head was used? Thanks, Jim.

[swfarrier]

I see we have some interested new ones coming online to the forum. If anyone has information concerning post #8, I'm sure they would find it interesting as well. Any takers?

[ckurz7000]

You know that the mast is too stiff if its resonance frequency is too close to double the rotor's rpm. If that happens, you have a lot of 2/rev vibrations shaking the gyro.

-- Chris.

[swfarrier]

Thanks Chris, That's the first time I've seen an difinitive explanation on the relationship between the two. Is it possible then to increase the length of the mast using the same materials to lessen the frequency of the two rev vibrations? In alot of specifications on Gyros, I notice the overall height at close to eight feet, however, some gryos are farther off the ground due to the landing gear and this gives no hint of the approximate length of the mast itself. I understand that some masts have to be shorter than others due to the necessity of hand starting. Is there an optimum length or is mast lenght found by trial and error?

[Russ Hobbs]

This is my understanding of who needs a slider. If you have a two place machine, the slider is a good option. There is no real value to a single seat machine. This was the explanation Ernie gave me, along with a little technical insight.
Russ

[ckurz7000]

...Is it possible then to increase the length of the mast using the same materials to lessen the frequency of the two rev vibrations?...

Yes, in principle it is possible. But whether or not this is a good idea depends on a lot of other things. Unfortunately changing one paramete,r like the length of the mast, changes other things as well.

-- Chris.

[Alan_Cheatham]

To determine if a slider will work or not would involve calculating the coefficient of friction and force required to slide the steel pins in the DU bushings verses the deflection of the mast as a cantilever beam from that sliding force. If the mast is already flexible it will deflect (bend slightly) rather than the pin sliding and hence render the slider head ineffective, many single seat gyros, but not all, fall into this category.

If the mast is of shorter cantilever length, has stiffer construction, or is more triangulated in design, then the slider is more likely to slide than the mast is to deflect and this makes the slider head more effective. Two place ships fall into this category.

In order for a slider head to work it must "slide", and in the case of most heads that involves two steel pins sliding in DU bushings, all the while carrying a suspended load. Depending on the fit and finish of the pins, lubrication, bearing characteristics, load, modifying effects such as rotor vibration and centering spring tension, etc., you end up with a certain coefficient of friction between pin and bearing that translates into so many pounds of drag force and that applies a bending load on the mast. Because of the variables here real world test results would be better than calculated numbers.

To date I have never heard of anyone coming up with any method to calculate or measure mast flexibility/slider-characteristics to determine if a slider will be effective or not, most just eyeball the frame design or try the slider out of desperation to stop excessive rotor shake.

.

[GyroDoug]

The Butterfly Super Sky Cycle is an example of a single seat machine that was designed to use a slider head. I suspect the reason it is needed, is because the SSC model uses a triple redundant mast (made up of 3 separate 1x2 tubes) and that makes it stiffer than most single seat masts.

[Greg Mitchell]

Doug,

I have one of Larry's super sliders on my Monarch.

Alan,

Excellent explanation.

Mitch.

[swfarrier]

Thanks for all the common sense, valuable input from either practical experience or technical background. The picture is now much clearer. Jim.

[Friendly]

Alan
If the towers that attach the head where suspended by bushing, like the motors mounts are, would this have the same effect as the slider, by allowing the head some flexiblity?

[Alan_Cheatham]

I've see some attempts at what you may be suggesting but have no information on what the results were.

.

[mark treidel]

Both Bill Clem & myself have slider heads on our 914 & 912 Dominators respectively.
Personally, I think it makes a large difference on a single place heavier unit. We also have the dual bearing heads.

[Greg Mitchell]

I agree with Mark 100%.

My Monarch is fully loaded up with MLS pre-rotator and AllTerrain G Force Landing Gear, 10 gallon tank and my fat butt. Has a stiffen mast to deal with the high torque pre-rotator and a super slider installed.

Found another pic from my build pics.

Mitch

[Aviomania]

I have an RFD slider heat from a customer and need to replace the bushings.... does anybody know the material used? Thanks.

[C. Beaty]

The bearings are Garlock DU bushings.

But I don’t know the part number.

If you can’t find what you need on Google, E-mail Ernie for a part number.

[Aviomania]

Thank you Mr Beaty