New Rotorhub Invention:

[Rotor Rooter]

The link http://www.SynchroLite.com/1377.html is to a web page that describes a new style of rotorhub. This hub should offer significant flight-control and aerodynamic advantages over existing rotorhubs.

In addition, it will be very inexpensive to build. It should be of special interest to those who are into light and homebuilt helicopters.

This invention has been placed in the Internet and it is referred to on a number of forums so that it is firmly in the public domain. It can therefore be used by anyone and patented by none.

Would anyone be interested in producing a 3D rendering of this rotor?

Any criticism, comments, or questions will be appreciated.

Thanks;
Dave J.

[Victor Duarte]

hello dave,

thank you again for nuggets..
i cant honestly critisize nothing (yet ;) ) i m reading, but the answer to the question about a 3d render is yes. you can send me your dimensions by mail, i think i wont patent it :D not my kind.

i go back to reading ;)

thanks dave

edit 1 : after a look....
can it be 3 or 4 bladed ? isnt there something with gyroscopic precession with an odd number of blades ?
i suppose the imputs are on the blade root, the rotor being "leveled" by the elastomeric rings and then springed back..
what about lag damping ?

edit 2 : doyou use bearings (green) on the gimbal? , considering thet oscillate more than spin, couldnt you use self lubrificated housings ( check www.skf.com)

if you use elastomeric bearings inn the blade horn, its worth have a different design..

i also see ther is a possibility to fit it for a tip jet by having a hollow mast, unless the elastomeric joints wont resist 2 bars..

did you evaluate the weigh ? i can do that with solidworks..; mine is weighted about 45 kg with the blades... and without optimisation.

another advantage is that you could mount a parachute in the dome or an additional streamlined dome

its of interest, are you shure you dont want to patent it ?
theres a procedure in France called "enveloppe SOLEAU" this is not a patent but the gov certifies you deposited your envelope with the theme "new rotor" at a date... its not a warranty but helps, it costs about 35 $ ... and for information, there are persons whitch work is to chech these enveloppes and buy them, at any price, they may buy bullsh... like they can buy pearls...

[Helidev II]

DJ Looks good mate.
Ive only skimmed it so far, Ill try to start a model of it for you tonight.

[Helidev II]

DJ, Ive started a model of some of the parts from the drawings and pic on your site. I understand the way the system works, however some of the drawings are a little unclear on the way they go together.
Do you have any other drawings of the parts? Or anymore pics of the prototype model you made?
I should have something in a couple of days for you, but more info on the various pieces would greatly speed things along.
Fly Safe.
BTW, I put in a request with the mods that you be allowed to come back and play on PPRUNE, you winding up of the establishment has been sorely missed!

[Victor Duarte]

yes more info needed,

can i participate in something ? if you feel to draw it christian, it s ok, i will be glad to see how you proceeed with alibre.

i see some forums have a very sensible trigger ... we are in an asylum maybe ;)

[Victor Duarte]

dave, while christian makes a 3d view, i brought back an idea i was digging to make a swashplate whthout gimbal ( as you can see on the first pic) i love flexing metals ;)

and as my brain never stops, a little pushed by your design, i drafted a kind of design similar to tours, but with no gimbal... just a flexing cross, a compass under and an elastomeric part between them... am i fool?

BTW, have you DXF shapes or your "bells"

thank you

[Rotor Rooter]

Victor,

" can it be 3 or 4 bladed ? "

Yes. It can be any number of blades greater than 2. Two blades and a hub spring will cause a 2/rev vibration.

"isn't there something with gyroscopic precession with an odd number of blades ? "

Gyroscopic precession affects all rotors but it is minimal. Aerodynamic precession is the big one.

"i suppose the inputs are on the blade root"

Yes the blade pitch inputs are by conventional pitch horns.

"what about lag damping"

The theory is; The rotor does not know that it is tipped in respect to the mast. This is because of the Constant Velocity Joint. Cyclical Coriolis effect is by far the largest contributor to flapping and the need for lead/lag hinges but because of the CVJ there is nothing significantly causing cyclical Coriolis. Profile drag and other causes will cause some in-plane oscillation, but hopefully, it is small enough to be absorbed by the blades and hub.

" doyou use bearings (green) on the gimbal? , considering thet oscillate more than spin, couldnt you use self lubrificated housings"

Currently, the intent is to use conventional Control Bearings. Elastomeric control bearings would be optimal.

" i also see ther is a possibility to fit it for a tip jet by having a hollow mast"

Perhaps but there is no room at the center of the CVJ, that I can think of, to pipe a fluid from the mast to the blades.

" are you sure you don' want to patent it ?

To my thinking, there is nothing to be gained. The major helicopter manufactures have hundreds of patents. It appears that 80 to 90% of them are useless and maybe only 1/2 or 1/4 of valid ones are ever applied. In addition, the use of a particular patented item is only in the hundreds, since there are not many helicopters. I believe that rotorcraft patents are; at best a marketing tool for small startups and at worst, an inhibitor of progress.

Your rotor hub is interesting but as you think through it more deeply, you will find problems, such as dimensional changes etc.

[Rotor Rooter]

Christian,

First, thanks for the nudge at PPRuNe. http://www.unicopter.com/ThumbsUp.gif

Thanks also, to you and to Victor for the offers to model the rotor.

Will get back to designing the hub for the SynchroLite-Dragonfly (http://www.synchrolite.com/1350.html) [550lbs/2rotors] tonight. This should prove the concept and assuming that every thing works, it should be very easy to scale up to larger craft. The preliminary drawings or sketches will be ready soon.

Dave

[Victor Duarte]

hi dave, i joind a pic of what in meant by self-lube bushings..

about tip jet purpose, : are the kind of "bells" circular and closed ? if so theres a path for compressed air, if the elastomeric springs are sealed.. you just need to hollow the mast and the blade grips..

i m ok about lead damping, btw you can have a d3 angle

about patent, i agree with you, it costs more than it could benefit.

i keep thinking my idea of having a "Y" blade could simplify a lot, even if its harder to mold, what do you mean by dimensional changes ? rotation clearances? i m curious about your acccurate sight.

and what about "homebuilt" laminated bearings ? i have the paulstra catalog and they dont have a product listing for hat, only a know how for certain helicopter parts, they dont sell to particular, unless you have $$$$ to spend..

dont think i do bad comments, i just like to dig, just as i like you to do so ;)

cheers

[Helidev II]

DJ, glad I could help, I had just assumed that you had been busy. It had been getting a little boring in there without your constant challenging of convention. :D
I know that you know this pic, but I have posted it for a little clarity (for me).
http://www.synchrolite.com/1350.gif

The elasomeric bearing at the bottom has a bush where it contacts the mast?
The "bell" that houses the second CV is round and covers the whole hub?
Just figured out a couple of other questions for my self.
Ill have to email you some JPEGS in the next couple of days for you to post as I cant attach images without a web page.

[Victor Duarte]

i think you re about right chris, lets wait DJ

just thinkink with you and dave, the bells are not an easy part to machine : they must be cut in a plain cylinder or embossed, forged, then machined, or made in a foundry then machined..
for a low cost rotor, should be better to use tubes, plates and make an assembly or do you think in a composites roll ?

just thinking to another point, Dave, how do you configure the elastomeric dampers ? i mean, are shure they will deform just in the expected way? in a perfect angular deformation ?, personnally i would dimension them thicker, and perhaps givethem a circular hollow cutoff (hope you understand my frenglish)

lets go lets go :D

[Rotor Rooter]

The postings caused a little flurry of activity. Now back to drawing then making the thing.

Victor

"what do you mean by dimensional changes"

When the swashplate in your picture tips, the bands, which are showing stress (I assume), must increase their length. This means that these bands can lengthen or deform under other types of loading and this is not good.

[']"are the kind of "bells" circular and closed ? if so theres a path for compressed air, if the elastomeric springs are sealed.. you just need to hollow the mast and the blade grips."[/i].

The mast, the rings and the rotorhead (blade spindle holder) are all moving in relationship to each other. Perhaps flexible tubes could go from the mast, below the rotorhub, to each blade.

Would you elaborate a little bit more about your thinking for the 'hub springs'.


Christian,

"The elasomeric bearing at the bottom has a bush where it contacts the mast?"

The eight bearings at the top might, now or later, become elastomeric bearings, to eliminate the need for lubricating. It should be possible to find the appropriate size of off-the-shelf elastomeric control bearings.

The hub springs will probably be strong compression springs (die springs) or elastomeric mounting pads. Lord Corporation makes some small mounts that might do. There will be a ring of these partially compressed 'springs' between the rotorhead and the Bisector skirt and another identical ring between the Bisector skirt and a ring attached to the mast. When the head tilts at a specific azimuth, the 'springs' at that azimuth will compress further and thereby resist the tilting. The 'springs' on both sides of the skirt at this azimuth must compress the same distance so that the Bisector tilts exactly one half the amount that the rotorhead tilts.

"The "bell" that houses the second CV is round and covers the whole hub?"

The parts have been labeled and I assume the "bell" is the outer housing which I have now called 'bell' and to which the blade spindles are attached. The current thinking is that this 'bell' is a round 'ring' with perhaps a cap at the top for inspection.

I'll post anything you want. In addition, the invention is only of the concept. If you come up with stronger, cheaper, simpler etc. ways of improving the parts, please say so.

This is really designing on the Internet, :D When I change the working drawing it changes in your posting.

Dave

[Victor Duarte]

hi dav and chris, sorry i ll be short and no drawing today, me and my GF just have to go for the maternity. our baby's coming !!

yes on my drawing the flex will bear stress, titanium can bear it, i have a price-list, i can have a plate of the double this size for 35 euros, affordable, BTW the cross plate can be holded in the center but left sliding free on the outer ring between teflon strips, lets say its a call back spring.

"The mast, the rings and the rotorhead (blade spindle holder) are all moving in relationship to each other. Perhaps flexible tubes could go from the mast, below the rotorhub, to each blade."

ok i thought the elastomeric skirts were all around the bells but appearently not , wrong ?
again with tip jets : no need tubes (flexion, vibes stress etc), just bind a molded part under the outer bell a kind of "mushroom" part, inserted in the mast, with build-in tubes, and a outer hollow ring thats distributes the air, but i still thinking your whole head could be fine if sealed and acting as a pressure-reserve.. ( a little like the XV1)

"Would you elaborate a little bit more about your thinking for the 'hub springs'."

i ll make a sketck, but, a perfect band wil not necessarely compress the expected way, it may escape or bend out or in, particularly if the bounding is not perfecyt or if the material is not perfectly homogeneous. the idea was to have a little holow cavity to force the band to compress in a way like : [o]
BTW leastomeric materials have a inner resonnance freq, from very low 5hz to higher 25-50 hz, dont you fear some resonnance?

"The eight bearings at the top might, now or later, become elastomeric bearings, to eliminate the need for lubricating. It should be possible to find the appropriate size of off-the-shelf elastomeric control bearings."

dave i m curious of your sources, have you a reseller? and why are you against composites bearings, they are cheap, lubed for life for certain models and...machinable and can bear heavy radial charges..

did you think about teh possibility to mold your own elastomeric, have you info on such chemical components to do that ? the adnantage is that molding them could be easy and you can reinforce them with roving or steel or whatever

thats a good work, i like it

[Rotor Rooter]

Victor,

It sounds like you will be up late for a few months and it won't be on helicopters. :)


" i thought the elastomeric skirts were all around the bells but apparently not , wrong ?"

They were but everything is in flux.


" just bind a molded part under the outer bell a kind of "mushroom" part, inserted in the mast, with build-in tubes, and a outer hollow ring thats distributes the air, but i still thinking your whole head could be fine if sealed and acting as a pressure-reserve."

Excellent idea.


" Would you elaborate a little bit more about your thinking for the 'hub springs'."

The elaboration will be placed on http://www.synchrolite.com/1350.html


" elastomeric materials have a inner resonance freq, from very low 5hz to higher 25-50 hz, don't you fear some resonance?"

The resonance is far above that of the rotor and therefor it should not cause a problem.


" why are you against composites bearings"

I have thought of them as bushings and I believe that sliding friction in helicopter bearings is a no-no. :)


" did you think about the possibility to mold your own elastomeric"

Yes it is a possibility. http://www.synchrolite.com/B332.html


If you disagree with any of the above, please say so.

Dave

[Helidev II]

Dave when x outer moves does the yoke as well?
On the drawing the x outer in red shows angular movement but the yoke is in the smae place.

[Rotor Rooter]

Christian,

The drawing on your posting is the working drawing, which is being used and changed as my thoughts progress (or regress :( ). It is changing because the Internet is used as a remote backup for my computer data. It is not a finally drawing, and at times things on it may not make sense.

But, the following basics ARE cast in stone.
Re the following remarks. In the plan view, the vertical axis is up/down the drawing and the horizontal axis is across the drawing.

The [Yoke] is firmly affixed to the [Mast].
The [X-inner] teeters on a vertical axis inside the [Yoke].
The [Bisector] teeters on a horizontal axis about the [X-inner].
The [X-outer] teeters on a horizontal axis about the [Bisector].
The [Bell] teeters on a vertical axis about the [Bisector].

In answer to your specific question, the [X-outer] can teeter about both axes independently from the [Yoke].

An excellent understanding of the basic Concentric Double Universal Joint can be seen here (http://www.cvcoupling.com/thompson_coupling/index_coupling.html). Glenn Thompson refers to his coupling as a 'double cardan joint with a zero length intermediate shaft'. Both couplings achieve the same results. The difference is that Glenn uses small linkages to bisect the angle whereas this one uses a Hub Spring to bisect the angle. Glenn's offers no resistance to angular displacement , this one does.

Dave

[Rotor Rooter]

Victor.

You were correct and I was wrong.

You said;- "" why are you against composites bearings"'

I said;- "I have thought of them as bushings and I believe that sliding friction in helicopter bearings is a no-no. '

The Bell 47 and 206 use ball bearings in their teetering hinges, It appears that smaller helicopters, such as the Robinson R22 uses bushings, and the Mini 500 uses journal bearings.

Thanks, and how is the 'family'?.

Dave

[Victor Duarte]

hi dave, no problem i ll be wrong much more than you will be ;)

i read years ago about a totally bearingless rotor, the mast was in a composite bearing .. dont know more

but in your rotor, there is no spin, just oscillations, btw, you damp your rotor, so, a little friction is not rectrictive.., and ball bearings dont like small angular mvts, risks of overloading some balls and create an accentuated erosion, ball bearings need a good ball circulation.. my opinion

i told you in other post about and idea of how to do an elastomeric damper whitch acts like an hydraulic one, here it is,
the idea is to have a "sponge-like" effect, so, no back spring forces

we can do that by drowning a shaped tank of fluid, can be grease, silicon, water,oil, depends, in fact, the damper has separated cells, full of fluid, but communicating by a tiny hole, so, the pression empties one cell or others but with a determined speed (like in an hydraulic damper) and if the emastomeric used is soft enough, it can keep the shape a little time before coming back to its initial state....

what do you think?
thanks dave and others

[Rotor Rooter]

Victor,

" as i see it, your rotor head is a kind of dampened gimbal, or am i wrong, i may not understand the concept of double joint..."

This explains the concept of the double universal joint. http://www.synchrolite.com/1377.html#Supplementary_Notes

" cant you be certain you dont need lad damping ?
this is important for me to know that because, assuming that, i also could simplify my design.'

An articulated rotor's lead/lag motion is the one that requires the mechanical damping. This rotor will not require lead/lag damping, hopefully. This statement should become clearer upon understanding the result of using a constant velocity joint

As for teetering, the teetering angle will only be +/- 8-degrees. The springs will be very strong, therefore their frequency will be very high. There may be some aerodynamic damping.

Time will tell and it shouldn't be too far off.

Your elastomeric is an interesting concept. A concern is that it will probably give different rates of damping at different azimuths.

Dave

[Victor Duarte]

hi dave, right about the shape of the cells
it was a moke up, in fact the cells should be aranged this way, or like honeycomb..

i still reading your website ;)

thank you

[Victor Duarte]

ok dave, sorry i missed one word "double", and better have read carefully your website, done, i understand now your concept, right, you avoid differential azimutal speeds due to gimbal (is it the correct word?) or cardan by adding an extra "null" cardan,

well, your concept relies on the fact that the 2 bisectors MUST be equal... mmm..plain elastomeric may have sligh differences unless you make their defoormation perfectly symetrical, homogeneous material, equal binding conditions... or... an interleaved laminated system (one on the inner, one on the outer bisector etc...) it s better to have a pile of elastomeric lamina, with a small delta (error), than a plain one with a bigger delta (theres a rule about that, dont remember the name, that says it s more precise to add a sum of small effets than to have an only one, this shares the delta errors and makes a "controllable average")... am i right or wrong ? or do i over-stress my self ?

thank you dave for making me have a brain-teaser while drinking my morning coffee :D :D

cheers

[Rotor Rooter]

Victor

Your second idea looks better, if you can stop the partitions from deflecting.

Now it's time to make a coffee, also, then go and read an interesting thread on this subject :) http://www.eng-tips.com/viewthread.cfm?qid=99412 ~ A discussion about Cornay Joints and others on Eng-Tip - Transmission and Driveline engineering Forum

[Victor Duarte]

hi dave, you know my account has been deleted on eng tips so i dint insist..
maybe i ll give it another turn..

what do you mean by "deflecting" ?

thank you dave

[Rotor Rooter]

"what do you mean by "deflecting" ?'

I assume your intention is that as the pressure of the liquid increases in one cavity it flows through the partitions small openings in the partitions to the adjacent cavities. If the partitions are flexible, they will bend under the pressure.

[Victor Duarte]

yes , right, excepted if the "common canal" is over the cavities , or separate from them
in my lag damper there are 2 cavities, linked by a ring canal, i ll post the scheme
i just think to make a test and mold one, i ve resolved the problem of the inner shape by using "freezed" grease or oil or a kind of mineral jelly, joined by thin plastic tubes full of grease

do you know about a white liquid made from corn (yes!) , i dont remember, that is liquid normally but gets as hard as fresh concrete, or more when hitted by a shock ?

have you news about you, or are you elsewhere ? i heard about prune , what is it?

thanks !

[Rotor Rooter]

"have you news about you, or are you elsewhere ? i heard about prune , what is it?"

I'm just working on the Constant Velocity Joint w/ Hub Spring (http://www.synchrolite.com/S_Hub_CVJ.html) Rotorhead for the SynchroLite

It is a forum for commercial helicopter pilots. Click on PPRuNe (http://www.pprune.org/forums/) Then go to [Rotorheads]

[Victor Duarte]

ok dave, i created an account but , just still have an overview for now...
i read your progress... much work done !
i m still thinking you can do bettter on blade grip, indeed
not to say i m a genius, not at all, but when your design will be ok, with your permisssion, naturally i ll try to figure adapting my Y blade root on your hub.
the reason is simple, the blade grip is the center of huge efforts and the grip bushings inserted in blade root are critical, in my design, note that the flap efforts are shared in traction in each Y branch and the section of the blade root can be smoothed to spread bending stress ... BTW if you assume you forget lag mvts, in my design the ball can be replacedd by a "ball pen point" , my concern being in to fin the two correct metals for this contact..

for now i must structure my work and make a site, i ll explain why my blade can fit a tip jet, a coax (with drag yaw control) and even, if you re fan, a flettner controlled blade.. of just a simple blade ...

i read carefully your calculations very helpful, i read 15 000 N of normal centrifugal effort you mean vertical ? because on my evaluation of the centrifugal effort on one blade (each 4kg, tip speed 900 kmh) the amount i found was more closer to 100 000 N each... what s wrong ?

i have the PAULSTRA catalog with their elastomeric dampers and some of them have enough radial tolerance to allow pitch control.. is it worth a conical laminated bearing ?

you told about composites bearings in your site, can you give me the link plz ;)
i m convinced all bearings can be avoided..did you hear about GRAPHALLOY bearings ?

dave, excuse me if i look "teatcher" thats not my intention, i m just writing as i think,
and i have not a basic academinc knowledge on aerodynamics, you have
i m like a wild musician playing nice melodies but with no structure, and you re an academic musician with very good basics...whitch does not mean talentless ; )
both have adventages, sometimes, classical musicians cant get out of their academic schemes while wild ones invent without knowing they invent..

i m naive

thank you dave

[Rotor Rooter]

Victor,

" for now i must structure my work and make a site,"

Yes. If you get a site it will make it a lot easier to discuss things. Anglais si vous svp :)

" you told about composites bearings in your site, can you give me the link plz
i m convinced all bearings can be avoided..did you hear about GRAPHALLOY bearings ?"

After your mentioning of composite bearings I searched and found Rexnord Tuflite composite bearings. (http://aerospace.rexnord.com/CatalogPDF/tuflite.pdf ) If you find that the Graphalloy bearings are better, please say so.

[Victor Duarte]

dave, i dont know much about graphalloy http://www.graphalloy.com/
i asked here but appearently, no one knows.. i "feel" them heavy, not so frictionless, but machinable and overall, erosion tolerance, i think it could be right for my design ball housing..

OH MAN ! i had a blast with the link you gave me !!
see special designs, they just do what i was looking for : ACME nuts, and hexa hollow bushings (but still searching for the screw you can see).... wow thanks thanks thanks

i work on a simplified swashplate, no need for complicated rods systems, the advantage being a powerful and precise control, even ready for fly-by-wire (yes), but the disadvantage is no feedback on the stick...

i ll tell you more...

cheers dave