2 'out there' questions....

[The_Sandman]

.....messing with RC helicopters as a means to test new ideas....... wondering if anyone knows anything about the following:

 

 

1.) NOTAR TAIL SYSTEMS: Any suggestions on how I might scale this down or if it is even a scalable concept?

 

 

2.) If one were to put SOLOR PANNELS or something similar on a main rotor blade, would the rate of sunlight absorbtion be effected if the blades were spinning or not? I had an idea that perhaps spinning blades might be exposed to more relative surface area than stationary blades and perhaps increase effeciency of solor pannel absorbation....

 

Told you these were off the wall......

 

 

A FEW MORE:

 

- if you had a rotor hub that absorbed n percent of the vibration comming from the blades, at what point (n), if at all, might a lag and flap hinge NOT be necessary?

 

- Would the ability to stiffen/soften the dampening or to change the dampening on the lag or flap axis allow for a more rigid rotor design? - Do you think it will be possible to completely eliminate the need for lag/flap allowance in rotor design?

 

- If you were to create a situation where the blade tips helped to drive the blades and therefore offset some of the torque forces the tail has to overcome, DOES THE TAIL MIX or Total Rotor Thrust / rotor drag ratio remain the same? - have a scale concept that no matter how I mix it, the gyro does not want to hold the tail!

 

 

Sorry for the goofy stuff, I have so many ideas and I am looking for some more experienced minds to help me decide what is worth the time and what's not.

 

Thanks again,

 

Sandman

[apiaguy]

answers:

1)yes you could scale it down... it would just take some messing with to establish the proper pressure in the boom and the length of the slots on the bottom and side of the boom and then you have to add a servo that changes pitch on the notar fan and a servo to control the nozzle on the end of the boom.. you could probabaly combine those.

2)No, you would not increase surface absorption of the solar panel by spinning it.

3)Yes you can eliminate lead lag hinges in a rotor system by allowing the rotor blades and rotorhead take the forces. Look at a BO-105 sometime... it has as close to a completely rigid rotor system as anyone has mass produced. There have been some attempts at a "true" rigid rotor design but none have been in production. The rigid rotor design on the BO-105 is one of the reasons the helicopter can do aerobatic maneuvers.

4) yes, if you create thrust at the tips you won't need as much anti-torque. That having been said, you are trying to only "aid" in thrust of the main rotor and not drive the system purely by tip-jets? That maybe why it is so difficult. I believe it was hiller that had the tip jet helicopter that didn't have a tail rotor at all.

[Linc]

A FEW MORE:

 

- if you had a rotor hub that absorbed n percent of the vibration comming from the blades, at what point (n), if at all, might a lag and flap hinge NOT be necessary?

Those two hinges have nothing to do with absorbing vibrations.

[apiaguy]

I would have to somewhat disagree with the statement: "those two hinges have nothing to do with absorbing vibrations"

 

"The hingeless rotor system (semi-rigid) functions much as the articulated system does, but uses elastomeric bearings and composite flextures to allow for flapping and lead-lag movements of the blades in place of conventional hinges. Its advantages are improved control response with less lag time and substantial improvements in vibration control. It does not have the risk of ground-resonance associated with the articulated type, but it is considerably more expensive."

 

Yes, the primary function of the lead lag and flapping hinges is not vibration damping but it certainly is at least secondary. Any track, balance and phasing of the rotor system is a combination of adjusting those "hinges".

 

Certainly Sandmans original comment was crude in formulation and lacked description but the intent was correct.

[Linc]

That is not what those hinges are utilized on a helicopter for. Even your disagreement verifies my statement since your example rotor system is not a fully-articulated system with lead/lag and flapping hinges.

 

You may design in the capability to absorb vibration, but that is still utilizing the hinge. There is no adjusting of lead/lag or flapping hinges during track and balance. There is adjustment of feathering hinges through pitch change tube adjustment and placement of counterweights (I'm sure you knew this, but I'm Captain Obvious). Again, even in whatever source you provided, vibration absorption is a byproduct of using a specific rotor design, not by designing the hinges out through absorbing the vibration.

 

It isn't a crude formulation, it is a total misunderstanding of what those hinges do and why they are there.

[nsdqjr]

You guys stop arguing, it's ruining all my excitement about the new fully rigid, solar powered, notar, jet tip assisted helicopter!! I can't wait to fly that thing!!

Edited February 12, 2007 by nsdqjr

[apiaguy]

I'm not sure what kind of helicopter you fly (besides your 58) but THERE ARE adjustments on the lead-lag dampers to adjust phasing on many fully articulated systems with elastomerics. In the old days before elastos you had to add tip weights to balance each blade so that you could minimize vibration from an out of phase system. Now all you have to do is adjust the clevis that adjusts the static position of the blade in the lead lag phase.

[The_Sandman]

4) yes, if you create thrust at the tips you won't need as much anti-torque. That having been said, you are trying to only "aid" in thrust of the main rotor and not drive the system purely by tip-jets? That maybe why it is so difficult. I believe it was hiller that had the tip jet helicopter that didn't have a tail rotor at all.

 

I think tip jets are a great idea, but like in acounter rotating system, don't you need the other blade in order to turn r/l?

 

I was considering the idea, but without a tail rotor, I would have a Gyrocopter right: Gyrocopter

 

Those two hinges have nothing to do with absorbing vibrations.

 

Was not sure about that....I know that on my RC helicopters, that when dampeing (we use o-rings along the feathering shaft, sandwiched between two screws) and blades are too stiff or not loose enough to move in the lag axis, the copper will shake it'self appart and be so responsive, that if you sneeze, the next thing you see are parts flying at you from your heli slamming into the wall ...and well, I'm sure you can imagine the rest (a thought: I should start filming my flights so I can capture the crashes and play back in slow motion to classical music)

 

So lemme ask you then......without the lag and flap hinges (and no way to mitigate the effects that necessitate these hinges) how would a helicopter respond? I imagine that the faster the blades go the more out of balance the blades will become and eventually either shake appart or the blades would stress and possibly break off... either way......it's not good.

 

I am a newbie, but we all have to start somewhere........i'm the guy who is not too embarrased to ask the 'stupid' questions. but still, I am sorry if I seem crude or niave- I am an Engineer in the Digital Printing business and a tinkerer, inventer ect.....currently enrolled in Private Helicopter Flight training, but a newbie in every sense of the word. (By the way, if anyone wants 42" posters or blueprints, I would be glad to make them for you on my 42" hp designjet printer/plotters.....least I can do for the patience and time in answering my questions and allowing me to be a guest here on your forums) - also, if my questions or topics bug you guys or seems silly or distracting, please let me know and I will back off.....

 

Anyway...... another query if I may:

 

My understanding is that along the blade, at different angles of attack etc.....the blades produce lift from different sections and usually never accross the whole blade at one time. If that is the case, would not blade design benifit from say flaps, like on comercial airliners......producing better lift during different stages of flight...... is this just too complicated or simply not a good idea? Has there been anything done in this area at all?

 

 

Thanks again guys, apiaguy, linc....stop arguing or you won't get to see my "new fully rigid, solar powered, notar, jet tip assisted helicopter!!" .....it's almost finished - just waiting for the glue to dry so the feathers don't fall off......lol

 

 

Sandybrains.....

[Linc]

So lemme ask you then......without the lag and flap hinges (and no way to mitigate the effects that necessitate these hinges) how would a helicopter respond? I imagine that the faster the blades go the more out of balance the blades will become and eventually either shake appart or the blades would stress and possibly break off... either way......it's not good.

Without provision for the flapping hinges or some system designed to provide similar function in the rotor system, the helicopter will flip over as it begins to translate laterally due to dissymmetry of lift. Likewise, without the lead/lag hinges or similar provision (even the offset teetering hinge does this), the blade or its mount on the hub will ultimately fail due to the fatigue caused by coriolis effect. Both are lessons learned long ago by Juan Cierva, father of the autogyro and the fully-articulated rotor system.

 

Balance and tracking are primarily features of production differences between blades in both weight and lift produced across the blade. On your aircraft, if the o-ring is too stiff to allow it to hunt appropriately, it may be too stiff to allow it to feather appropriately as well, which may create an out-of-track condition and could explain the vibration. Just a guess, because I've never maintained an R/C helicopter before.

 

P.S. I didn't mind your questions.

[HelliBoy]

Alright, here goes nothin...

 

with the removal or in-fact-removal of your lead lag hinges it sounds like you're encountering ground resonance, in which the helicopter self destructs when coming up to rpm. In order to have a workable model in which the rc heli could fly without flapping/lead lag hinges you'd need to have a blade that can absorb those forces in a manner which does not unbalance the rotor system. You'd also need to have perfectly balanced blades along with perfect phasing of the blades (ie. for three blades you'd have to have exactly 120 degrees between each one). Remember, the forces which nessecitate lead lag and flapping hinges dont go away when you remove those hinges. I'd suggest develloping a blade that resembles more of a noodly strip of rubber than a real helicopter blade. With enough mass, the blade will become rigid enough to support lifting forces through centrifugal force and flexible enough to twist and bend to cancel out the need for the flapping/lead lag hinges.

 

Many of the other questions you're asking can be answered with the lift formula

L=CL*1/2P*S*V2

 

L=LIFT

CL=COEEFICIENT OF LIFT OR SHAPE OF THE AIRFOIL

1/2P= ONE HALF THE AIR DENSITY

S= SURFACE AREA OF THE BLADE

V2= VELOCITY SQUARED (!!! MOST IMPORTANT)

 

The advancing side of the disk is producing more lift in forward flight so it tries to cone up, the flapping hinge allows this to happen. As the blade flaps up, its angle of attack is effectively reduced, thus equalizing both sides of the disk. If you dont allow this to happen the helicopter will roll over in forward flight.

 

And Corriolis effect (which happens when the blade accelerates or decelerates when it moves up or down)

 

CF=M*V*R

 

CF= Coriolis force

M= mass (constant)

V= Velocity

R= Radius (as in the radius of the center of mass of the blade from the root)

 

so if a blade moves up, it accelerates because its center of mass is getting closer to the root, if it moves down it tries to slow down. This is also called the conservation of angular momentum and explains the need for lead lag hinges when the blade is flapping

 

 

 

Now take everything I just said and turn it 90 degrees...thats gyroscopic precession.

 

 

Theres a reason the geeks who come up with this stuff are called "engineers"

Edited February 12, 2007 by HelliBoy

[The_Sandman]

I'd suggest develloping a blade that resembles more of a noodly strip of rubber than a real helicopter blade. With enough mass, the blade will become rigid enough to support lifting forces through centrifugal force and flexible enough to twist and bend to cancel out the need for the flapping/lead lag hinges.

 

I had this strange idea that if you could somehow measure the lift/drag forces along a blade as it's moving AND if you had developed a system of flaps or the like, you might be able to get more lift along the blade at any given time and, as I am learning, eliminate the need for mitigation (lag and flap hinges) and all the benifits that they may provide in their abcence.

 

(Just my opinion here)

In other words, it seems that a simpler design may not be the answer in helicopter development. I see development of systems that mitigate forces that we have not learned to control better. It seems that the conventional wisdom is to work arround the problem with systems that treat the symptoms instead of solving the underlying problem itself. I think early developments were made in a rush to achieve flight..... solving each problem or creating work arrounds as you encountered them.

 

I doubt that engineers created this stuff as suggested, in my humble opinion, the engineers came later and explained what was happening or describing an investigating the results. If we were to go back and absorb everything academically related to helicopter flight principals first, and then start from scratch to build a helicopter, I doubt the design would have been thae same.....feedback?

 

 

 

I belive that inventers created this stuff and it shows in the 'reactionary' evolution of helicopters- work arrounds, mitigation techniques........ok...we (man) can fly now.....let's step back and solve some of these problems instead of createng workarrounds ....which in turn introduce more varriables and issues to the mix.

 

I may sound outragously niave here, and perhaps am..........but I see future helicopters with no need for tail rotors. A blade design that is just as complicated as it needs to be but no more - I see future helicopters employing (if I may coin a phrase) varriable blade shape technology. Dynamic advances in computer technology might allow each blade to sense it's position in relation to one another and to twist and shape itself into optimum shape for each condition. Maybe even a mechanical or hydrolic system that inflates portions of the blades at certain positions which employ mechanical balancing......the leading side of retreating blade inflates some while simultaniusly as a result the trailing side of the advancing blade deflates......or something like that.......

 

Sorry, i'm going off again.

 

Interesting enough, I decided to pick up this book:Principles of Helicopter Flight- ISBN 1-56027-217-1 Covers alot of what your telling me Heliboy and I have been reading and taking notes.....but my imagination goes off and I get these ideas and well A.D.D. sucks but between that, aquiring my private heli rating and the continuation of my RC Heli tinkering, I think I will wrap my mind arround this and watch in wonder as I peal each layer away..... and I am taking my time.

 

Thanks guys.

 

Helicopters are so .... interesting....not the flight aspect either, the mechanics, the science. All of it. I thirst for as much knowledge as I can find from whomever is willing to give it. . Small steps....

 

as Igor Sikorsky said,

 

The helicopter approaches closer than any other vehicle to fulfillment of mankind's ancient dreams of the flying horse and the magic carpet.

--Igor Sikorsky

Edited February 12, 2007 by The_Sandman

[HelliBoy]

I commend your attitude, and eurocopter must've stolen your variable blade shape idea; they're experimenting with blades that have electronic panels on them that expand and contract to effectively feather the blades which eliminates the need for swashplates...its along the lines of the small mechanical flaps on the blades that Kaman K-MAX's use for blade pitch change.

There are a bunch of heli's with no tail rotors Im sure you know but economics dictates we build and buy heli's with a single rotor and tail rotor. (check out the Fairey Rotodyne for some inspiration)

Your dream of tail rotor-less helicopters sounds great but torque is torque and you cant just wish it away. Nor can you wish away the tendency of a blade to flap or lead/lag...they are facts of physics and I think the term 'workarounds' takes a very simplistic view of basic engineering principles. Physics can only be accomodated for in design; not eliminated.

Keep plugging and good luck.

[AndrewT]

I see future helicopters employing (if I may coin a phrase) varriable blade shape technology. Dynamic advances in computer technology might allow each blade to sense it's position in relation to one another and to twist and shape itself into optimum shape for each condition. Maybe even a mechanical or hydrolic system that inflates portions of the blades at certain positions which employ mechanical balancing......the leading side of retreating blade inflates some while simultaniusly as a result the trailing side of the advancing blade deflates......or something like that.......

 

 

 

In a fully articulated system, the blades DO change pitch according to the relative position of the other blades, its the function of the lead/lag hinge as has been said before. I'm also don't think that the blades maintain the same angle of attack from the hub to the tip. I'm sure you know about the Coriolis Effect, in which the blades cone upwards as the helicopter takes flight. It would seem to me that as the blades cone up, the angle of attack would be varried from point to point along the blade. Doesn't that make sense?

 

In terms of helicotpers without tail rotors, there are many that exist. Probably the most interesting, and wildly complicated, example is the KA-52 (pictured below).

 

 

 

 

If this kind of aerospace engineering is of interest to you, then perhaps you should take some classes or read books about it before you get too hard on the engineers who brought us these wonderful machines in the first place! Keep chipping away though, because you never know what you might find.

Edited February 12, 2007 by AndrewT

[The_Sandman]

If this kind of aerospace engineering is of interest to you, then perhaps you should take some classes or read books about it before you get too hard on the engineers who brought us these wonderful machines in the first place! Keep chipping away though, because you never know what you might find.

 

 

Admonishment, humbly accepted. ....and your right. I can only hope to make up (for my lack of formal education in this area) with sheer determination and hunger for knowledge.......my retention level when I am interested in something has served me well over the years.

 

Look guys, I really appreciate the access to feedback like your giving. Again, please know that I appreciate and am eager to find ways to reciprocate..... Lucky to have found this forum me thinks!

 

 

Cheers!

 

 

Sands.....

[HelliBoy]

Sandy, here's your in blade 'flap' vibration dampers...way too small and complex for an RC testbed though

LINK

[The_Sandman]

Sandy, here's your in blade 'flap' vibration dampers...way too small and complex for an RC testbed though

LINK

 

 

Thanks Heliboy.....cool site too!

 

ok, you got my mind wondering again........what about this:

 

- If you could develop a material like rubber that you could use to contruct airframes, perhaps certain elements of rotor heads ect.....where you can adjust the stiffness or hardness of the material....like a muscle contracts. If you develop this material to react to say an electrical charge that causes it to expand or contact according to how hard or soft the pilot or sensors detrmine is neccesary to compensate for vibrational issues.

 

Dunno, might have a way of introducing even a short term emergency dampening so heli does'nt shake appart before one can land.

 

- if vibrations are like soundwaves, then one might be able to generate an opposite wave pattern or create a vibration freq that is exactly opposite of the offending vibrations... if this is viable....then why not place multiple devices that can do this in stratigic places on an airframe where they could work together to manage vibrations......maybe at hard points or joints or simply COAT certian structures in this (then it could be installed as a retrofit) - Recently I saw something on some Disneyland roller coatsers where they put rubber in between metal/metal contacts I assume to mitigate vibration. Maybe sound. But that's what gave me the idea.

 

 

....the system should also probably let the pilot know about this dampening or at least make them aware of the dampened vibration and a possible issue.....in other words I supose that if the system worked correctly it may mask vibrations that would indicate mechanical problems - this would need to be taken into account if we ever tried to use such a system I would imagine.

 

 

OK....thats's my goofy idea for the day.

 

....making appt. for an intro flight (private heli rating) today for friday. Excited. But nervous since I have been reading up on R22 safety issues......these are safe birds right? I mean the beta II has been upgraded for saftey ect.....but it sure seems that for a student, these choppers are very responsive, maybe too responsive for beginners. They have a low inertia blade system too which I feel is less forgiving I would imaging for newbies.... I dunno, they seem cheap and unsafe. But everyone uses them for training......any warm fuzzies anyone can pass along?

 

 

S.

[nsdqjr]

....making appt. for an intro flight (private heli rating) today for friday. Excited. But nervous since I have been reading up on R22 safety issues......these are safe birds right? I mean the beta II has been upgraded for saftey ect.....but it sure seems that for a student, these choppers are very responsive, maybe too responsive for beginners. They have a low inertia blade system too which I feel is less forgiving I would imaging for newbies.... I dunno, they seem cheap and unsafe. But everyone uses them for training......any warm fuzzies anyone can pass along?

 

R-22 are safe if flown within the approved limitations and flight envelope, just like most any other aircraft. All of the things that you mention, response, low inertia rotor system, etc contribute to make the student a better all around pilot, in my opinion. If you can safely operate an R-22 you should be able to safely operate just about anything. Also, the issues that you stated, and that will be addressed in your SFAR 73 Awareness Training are NOT Robinson specific. Many other helicopters share some of the specific quirks that the R-22 possesses. Enjoy your intro and take it as a challenge, you'll be better for it in the end.

[Goldy]

....making appt. for an intro flight (private heli rating) today for friday. Excited. But nervous since I have been reading up on R22 safety issues......these are safe birds right? I mean the beta II has been upgraded for saftey ect.....but it sure seems that for a student, these choppers are very responsive, maybe too responsive for beginners. They have a low inertia blade system too which I feel is less forgiving I would imaging for newbies.... I dunno, they seem cheap and unsafe. But everyone uses them for training......any warm fuzzies anyone can pass along?

S.

 

 

So, how did it go ? Forget the low inertia stuff..just get the collective all the way down immediately....in one second you will have all the rotor rpm that you need back again. Just watch the low G pushovers...and focus on small movements with the cyclic.

[Linc]

Also, the issues that you stated, and that will be addressed in your SFAR 73 Awareness Training are NOT Robinson specific. Many other helicopters share some of the specific quirks that the R-22 possesses.

Which aircraft, which quirks?

[The_Sandman]

So, how did it go ? Forget the low inertia stuff..just get the collective all the way down immediately....in one second you will have all the rotor rpm that you need back again. Just watch the low G pushovers...and focus on small movements with the cyclic.

 

It went well. My instructor was good, and i'm not just saying that. He made comments at just the right moment to help me understand everything he was doing and why. Let me take the stick in flight and when we hovered. He made comments to himself like 'ok, i'm trying to do too much here, lets get it together' and 'alright, I see traffic up ahead, I wanna be aware of that' and well, other little comments that I knew were for me.....he was starting to get me thinking about other traffic and overloading my attention while flying. I did not say anything to him because I was focusing on flying but I heard everything he said.

 

During the hover, at one point he took hands feet off and I had full control..... my instructor said he was impressed that I was able to maintain a hover on my first flight......I told him that he probably said that to all his students....lol. However, when we got back to the office, his next student was there wating and I asked her if he told her the same.....she said he actually said she was terrible! lol....so I am not sure what to think......the owner seemed a little surprised as well....but with my Helicopter RC background, I think he and I both agree that it helped.

 

Overall, I think I can do this. However, I was hit with a dose of reality. I cannot, will not go into this lightly. I have 2 young children, twins, the LIGHT OF MY LIFE....and I would do nothing to take their daddy away......a 'dream' is not worth that. IN fact I used to not fear death at all.....I belive in GOD and know that is not the end, but when the twins were born, that all changed. I don't fear death for what I may loose, but what it would do to those who love me and still need me......THAT is a responsibility that trancends all others. So I have to factor the practical benifits to doing this versus the risk. This will take me some long nights out on the patio, thinking to wrap my mind arround.

 

I also don't want to get too old and have regrets about missed oppertunity.

 

Helicopters can be safe but I feel that I lack the confidence, at least right now, to fly them safely.....of course I require some skill and experience.....but I was thinking as we flew......'damn, I really need to know what the f*&@ I am doing here or I'm hozed for sure!'

 

RC choppers do look wicked cool when they hit a wall and fragment into a cloud of twirling piceces, sometimes I wish I captured the crashes on high speed camera.... either way, I can salvage, repair or replace them.......on the real thing, that's all different. So I need to adjust my thinking there as well.....before I can move forward.

 

I was surprised that the helicopter can be easily damaged (fataly so) by simply overcorrecting..... say in a hard forward and back movement ......even an instructor caught off guard would not have time to respond.....bam...mast bump. Yes the low-g warnings do scare me a bit, seems so easy to.....say in gusty winds, to create this scenerio w/o much warning OR MOVEMNET by the pilot.......I was aware of all this and my movemnets were ever so slight......in fact, I felt that the controls were MORE RESPONSIVE than some of my RC choppers.....this was surpising to me. I have helicopters that if you sneeze hard, it translates to the model and ....well, into a wall you go.

 

I need to watch my horizion, altititude and rate of decent. I want to perfect my hover before anything else.....I feel that if I can master the hover, it will be my steping stone for more confidence as I learn to fly these.

 

What else.....um, honest opinion, I need to really think about wether I am confident, agile and capable enough to make a safe helicopter pilot. I think I may have the raw skill and with training be a good pilot, but piloting skills alone do not make a good pilot.

 

I hope this all made sense......

 

Thanks for asking...

 

Sandman.

Edited February 19, 2007 by The_Sandman

[nsdqjr]

Which aircraft, which quirks?

 

Hey Linc, I was referring to the maneuver limitations of any helicopter with a semi-rigid rotor system.

[scubasteve]

Hey Linc, I was referring to the maneuver limitations of any helicopter with a semi-rigid rotor system.

 

 

First off, you a TF guy? OK....limitations will be set by the manufacturer first. A semi-rigid rotor system is subject to mast bumping (when under-slung) when limitations are exceeded. These limitations can be airspeed or bank angles. I may have forgotten a few things, but you get the drift.

[ECD]

Hey Sandman!

I’ll respond to your initial questions first, but only the one of a scale-down NOTAR..

Cool idea and lots of luck, but if you’d be interested in (what I think might be) a world first you should give the whole idea a spin. Instead of a conventional NOTAR (you can call them conventional by now..?), why not make a part of the entire tail boom spin? A cylindrical object rotating in an airflow will also create a force, normal to the airflow I believe, and this force is related to the rotation of the cylinder. The downwash from the disk would here work like with the NOTAR, only instead of the slits/slots you would spin a long section of the boom. Regulating the angular velocity would provide “thrust control”. OK, you would be forced to counteract yet another moment with your cyclic, but it would be original..

 

Also, I could see a way to build away the flapping like you mentioned. Instead of flapping, regulating lift through induced angle of attack, the airfoil could as you say be modified. However it would be hard to achieve major geometrical differences over the blade in the wanted Hz-range.. I suggest using a combination of flaps and magnetic actuators behind the leading edge. Flaps can influence profile and so control lift. The magnetic actuators I am talking about would raise tiny metal flaps (small parts of the blade skin) and break up laminar flow. Positioned right and working together it could be possible to regulate the lift of the blade on the way around the helicopter so that the unequal lift would be cancelled together with the need for flapping..

Edited May 30, 2007 by ECD

[Eric Hunt]

ECD said:

"would raise tiny metal flaps (small parts of the blade skin) and break up laminar flow."

 

You are advocating the use of spoilers?

 

The problem is that the retreating blade has too little lift, not that the advancing blade has too much. Start killing lift and your aircraft will not lift much or go very fast. Spoilers also increase drag, sucking up engine power and causing stress on your rotor head / drag dampers etc.

 

Think of the problem with spoilers that caused that B52 to crash at the airshow a few years ago. Steep turn, pilot tries to raise the lower wing. But the B52 uses spoilers instead of ailerons, so all that happened was that the upper wing lost more lift and the lower one stayed down. Splat.

[ECD]

ECD said:

"would raise tiny metal flaps (small parts of the blade skin) and break up laminar flow."

 

You are advocating the use of spoilers?

 

The problem is that the retreating blade has too little lift, not that the advancing blade has too much. Start killing lift and your aircraft will not lift much or go very fast. Spoilers also increase drag, sucking up engine power and causing stress on your rotor head / drag dampers etc.

 

Think of the problem with spoilers that caused that B52 to crash at the airshow a few years ago. Steep turn, pilot tries to raise the lower wing. But the B52 uses spoilers instead of ailerons, so all that happened was that the upper wing lost more lift and the lower one stayed down. Splat.

 

Well, the problem is not only having too little lift on the retreating blade but a combination with advancing egde, the up-flap on this side allready reduces lift today..

Also I’m not thinking of spoilers as ones seen on fixed wings, we’re talking about TINY metal flaps (placed behind/above the leading edge they could be small and still have great effect).. This would increase the drag/lift ratio a bit, but not significantly. A greater problem would be where to place them. They would have best effect at the tip, the last place you want to loose lift.

As to causing stress on “drag” dampers, there should be no lead-lagging and so lead-lag damping will not be necessary. This if it would at all work. But I think the prospect of removing flapping and lead-lagging would be a huge incitement to develop the technology.

 

Personally I would advocate developing control rods that can extend and contract them selves.

This would do away with the more complex parts of the swash plate (replacing it with even more complex control rods ; ) and allow for individual pitch control independent of blade position. Such pitch control would, IMHO, allow to do away with flapping and thereby lead-lag.. Sadly the most viable option, Piezo elements, will not allow for the amount of movement needed.. Try doing it any other way and you’ll have a system a lot more complicated than the worst fully articulated rotor head.