Mechanical Advantage and servo setups (Full Version)

All Forums >> [RC Airplanes] >> Pattern Flying



Message

MikeEast -> Mechanical Advantage and servo setups (12/27/2005 3:23 AM)

Im going to start this thread with an interesting reponse from Troy Neuman to a comment I made. His comment makes a lot of sense but I hadnt thought of it from his excellent point of view.

Mike East wrote
quote:

Gosh generally speaking in my opinion, I dont think you can get the servo TOO Close to the control horn as long as you have the structure to support it in the wing, and you have the mechanical room in the linkage. You will just need to make sure that you set the control horn in the right relationship to the servo to get the geometry you are looking for.. I would think that dual axis rod ends would give you a little extra freedom of motion so that the pushrod doesnt bind up at the servo arm or control horn.. On my Genesis,, the servo is so close to the control horn that I had to clip the threaded titanium rod ends for the CF pushrods off because they were too long end to end.

Assuming that the servo arm is pointing to the fuselage, I like to setup my geometry so that at full throw on my highest rate setting, the pushrod is parallel to the long side of the servo and paralled to the control horn, this equals max leverage at full throw.
When it comes back to neutral, the pushrod is angled slightly from the servo arm to the control horn and is no longer parallel to the servo. This should give you increased mechanical advantage as throw is increased and less at center, which is what you want... If you start out at neutral with the pushrod parallel to the servo and at 90degrees to the servo arm,, it looks pretty, but as as throw is increased the pushrod angles in or out and you are losing leverage,,, at least thats the way I understand it.. If Im wrong thats fine but thats the way it was taught to me and looking at it it really seems to make mechanical sense.



Troy Neuman wrote
quote:

Mike,

Good way to put that mechanical advantage thing.

Let me add a different view for you.

Where do we need the most mechanical advantage on say ailerons....It’s in the pull or push of a loop right. Where are the aileron servos sitting when you pull a tight corner? In a tight corner the servo needs to hold those ailerons as perfectly aligned at zero as possible at the neutral position so that the model loops properly right? If one aileron gives more than the other side then it will cause the loop segment to spiral off to one side. If both ailerons get moved by the forces then it will change the pitch rate of the model. This can look like a segmented loop in the extreme case and in a not so extreme case it can cause you to miss the exit line or the vertical (over or under pull-push). You end up pulling past the point where you need to stop so you adjust your flying through practice to stop a little earlier so that you stop going perfectly level after the vertical downline. Point is the surface will blow back some no matter what servo you have on it, and no matter how good the linkage. This is affected by the servo's dead band and power. Digital servos are much better at this holding power than analog servos of the past. But the better chance you give you ailerons of staying absolutely centered the better your loop segments will be.

If you want to prove this is the worst place for the servos power go put some standard 40oz servos on your ailerons. You won’t be able to pull straight corners consistently. However your roll rate will likely not change too much. This test will show that the servos at their end deflection values are not needing as much power as holding the neutral in the loop element. Now if you roll rate was cut in half going to weak servo then I would say you need to more powerful servo or maximize you linkage for this deflection angle.

The reason the roll rate will not change much going to the wimpy servo is because the aileron is acting with the wing to create lift in different directions for the roll. The load on the aileron itself during a roll is not as much as during a hard pull or push. In a roll you are changing the shape of the airfoil on the wing to create the lift and the wing is doing the work. In a corner (pull or push) you are using the servo to maintain the shape of the airfoil that is already there. So combine this with inertia and gravity and sometimes you can have some pretty high loads on the ailerons trying to move them off of neutral. How often do you fly across the sky holding aileron? If you are like me you level your wings and then you let the model fly with its wings level right? I flew today and I don’t think I ever held Aileron input for a sustained period of time. I held some rudder as we had a pretty good cross wind. But I don’t think I have ever had to hold a sustained aileron input to make the model fly a straight line.

This is where I feel the mechanical advantage is best in a pattern model.

For control throws we are only talking 10-15degs of travel on the ailerons anyway for precision flying. Now I will agree with you that if you are flying 3D and large control deflections are needed then you need the power out where the surface is deflected...but we aren't flying there with our pattern models.

Pattern sequences are flown with rates very low like I said 10-15degs and we are not using this for rolls. This rate with the stick pegged is a super fast roll rate so we are actually using way down in the 5-6degs for normal rolls. So I optimize my linkages to give mechanical advantages at this near neutral position. This is where I fly all the time and this is where I want the model have the most locked in feel. I want to level my wings and let the model track straight. I want to then get to the end of a horizontal line and just pull straight back on the stick and have the model loop to vertical aileron input free.

Again if we stick more servos on the surface then we can get more power out of the servos so less mechanical advantage is not a big deal. But we are not sticking 2-3-4 servos on an aileron like the big 40% models.


Now take my Showtime. I wanted it to be able to hold those large deflections 50degs and so on. So I setup the mechanical advantage to hold these deflections. I also stuck huge power servos on all the surfaces. This way I can do rolling Harriers like the big boys with the aileron stick pegged over at 40+degs and just hanging there on the prop. This is an extreme case. Now the guys that are doing 3D and Precision with their 40% stuff they are sticking 3-4 servos on a aileron to get enough power to overcome this geometry issue. Also the guys doing this on the big models are trying to get a compromise between precision and 3D rates. SO the use of the linkage that you describe is helpful in maintaining the control input and holding it there....but when you go to a precision setup you need more servos and more servo power to keep the surfaces in the right spot near neutral.

Think of this way:
In Pattern flying how often are you holding a sustained control input?

A vertical roll is about it…or maybe the entry into a spin where you are holding up elevator. However in the spin you have very little load on the elevator in this case as you are going slow. If you had too much speed the model would climb…All the other stuff the control input is changing over time and mostly it is at or near neutral position with only very small angles of deflection. So maximize your setup to work where you fly the most.

Just some food for thought. This is the not really the thread for this discussion as its the Insight thread but think about where you do most of your rolls in terms of stick inputs and rates...Then look at your model and see just how much your surfaces are moving you will be very surprised. The end points are not the important values but rather the position you stick them when actually flying a sequence.


I feel you will find a difference in the models performance by maximizing your ATV values and setting up maximum mechanical advantage at the servo neutral not its end points. Again different strokes for different folks.

There is also a discussion we can get into about maximizing speed of the servos output versus the power of the servos output....There are many ways to do it. There is more to a linkage and control setup than the parts wiggle in the right direction let’s go fly it!

Good discussion. I don’t many modelers think about this stuff when setting up their linkages.

Troy Newman



MikeEast -> RE: Mechanical Advantage and servo setups (12/27/2005 3:33 AM)

That is a REALLY good point that I hadnt considered. My thought processes were geared towards 3D where I have mega throws where I need plenty of holding power at 30-60 degrees of deflection. Seemed to make sense that you would want the same on a pattern plane, but I can see your point that especially on ailerons,, and elevator if you are using 2 elevator servos that you really need your holding power at center when you want to be off of the stick altogether.?
You are right, in pattern we almost never use full throw except for during snap rolls and vertical rolling maneuvers. So you are saying that you setup for maximum advantage at dead center and actually lose advantage as you move away from center to minimize blowback? Really with a DEPS setup and a pull pull Rudder I cant see having much control over mechanical advantage (at least not in the same way as ailerons where two surfaces work independantly of one another) on those surfaces but it makes a lot of sense on ailerons where you want your ailerons to really lock in and hold ESPECIALLY during a (relatively) hard push or pull.. You are saying that if you give away advantage at center, you can allow blowback that can cause the airplane to roll, even if you are slightly mechanically "offcenter"? hmm,,, I may be going back and making some changes... I learn something new everytime I throw my thoughts out on the table, excellent.

I can see myself learning a lot from this discussion...



MikeEast -> RE: Mechanical Advantage and servo setups (12/27/2005 3:45 AM)

Another really good part of this discussion is the relationship between optimizing resolution and mechanical advantage.

I setup my mechanics so that at full endpoint(ATV) 140 on my 9C, on my highest desired throw rate I can only mechanically get the maximum deflection angle that I need and no more.. If you have to dial your ATV(endpoint, or highest rate) down to get to your maximum desired throw then you are not taking advantage of the full sensitivity. Is that right?

For example,, you want your high rate elevator at 16 degrees but at 140 endpoint you are getting 20 degrees,,, so you dial back the endpoint (ATV) until you get 16 degrees you are cheating yourself out of 1024 resolution (or whatever your TX is capable of)? Ultimately you want to start off with your high rate on your dual rate setup AND your endpoint(ATV) at the highest number and then MECHANICALLY adjust your linkage to get 16 degrees( or whatever you want your high rate to be)? Thats the way I do it,,, is there a better way?



Troy Newman -> RE: Mechanical Advantage and servo setups (12/27/2005 4:13 AM)

Resolution wise you are correct. I use high number for end points. JR calls this travel volume, Futaba calls it ATV.

Now one common problem I see is guys blindly running their ATV values up to 140% without looking at what the actual deflection of the surface really is. For example I just popped open the 10X on my #1 Pinnacle. Aileron Travel Volumes:

Right Aileron (aileron channel) Up 132% Down 127%
Left Aileron (flap channel) Up 128% down 126%

This gives me exactly 13 degrees of travel on each aileron up and down. Why is this? Number one the linkages were built by human hands they are not perfect. The servo electronics are good really good but they can be off a few %. Two different servos will not have the exact same centers and end points. There are specs that play a role here.


After this is all setup I then add in my differential in the differential screen on the JR radio and I have 6% differential. My Flying rate is 10.5degrees with the 6% diff the down aileron travels right at 10degs. So I have 1/2 deg differential.

My flying aileron rate is at 80% and I use about 40-45% expo. I use the Full aileron travel of 13degs and the 6% differential added in for upline snaps only. All other snaps and spins are done at this low rate of 10.5degs and the 6% differential.

If you setup your ATV values very accurately this way then any value changes you make to the D/R setting is a equal value (68% left and 68% right) and you don't have problems with aileron differential and such when changing them. Speed up the ailerons a little then go to 83-85% on low rate for flying. Slow them down a little it’s a drop back to 76-78% rather than the stock 80%. Play with expo values the same way. With Travel Volume setup properly and accurately you can easily make these changes and you get consistent changes and the special trimming things like differential and ends points all track together

You must make the best mechanical system possible If you have horns different lengths or servos not centered up properly with subtrim then your ATV values will not track close together like the ones I posted above.
So make it mechanically correct as you can. If that means within 1 turn on a 4-40 bolt or a 6-32 control horn get it as close as possible. Then we use our radio and its end point adjustment to fine tune it so it’s absolutely as perfect as we can measure.

So get a good way to measure the values too. Again another discussion.


Next problem I see is guys run their ATV values up really high to 140% to get maximum resolution then run their D/R values back to 30% because they have way to much travel at 140% ATV. The answer I get is well I have max resolution because my ATV is at 140%.


Wrong! You are still giving it away running your D/R down low. A little trick Tony Frakowiack taught me. Go into your servo monitor screen. The Futaba 9C, 9Z both have it. The JR 10X and 9303 both have it. Look at the bars travel as you move your controls. If the bar graph doesn't get up to the 100% mark on the graph then you are not using you radio to it maximum resolution. When I started looking closely at it I was using 60-70%...now even though my D/R value is 80% I'm passing above the 100% servo throw mark on the bar graph. Reason is I'm 80% of 130-140%....

We pay $500-1200 for a radio that has all this performance and resolution why would you give it up by having a poor mechanical setup?

Troy Newman



majortom-RCU -> RE: Mechanical Advantage and servo setups (12/27/2005 4:18 AM)

I'm always interested in what TN has to say. A great pattern flyer I am not, but I do take it seriously.

I am entirely in accord with the principle of maxing resolution, and setting up throws that are no more than what I need for the maneuvers... so generally ailerons nmt 12 degrees, elevator ~10-12 degrees, rudder ~ 30-35 degrees. These throws I set up at max ATV. I always make my own horns, and calculate the moment arms to fit the desired throws--so I am normally using small wheels or short arms on ailerons, short arm on elevator (DEPS, thanx to Troy) and medium arms on rudder. I also favor the DARE connectors for the reasons Mike states.

I saw Chip Hyde's explanation somewhere recommending the principle Mike sets forth at the start of this thread, to give maximum leverage at full throw. I recognize this as applicable more in 3D/AA than in pattern, more for big throws than for max leverage at neutral.

I accept TN's argument that for pattern flying it's more important to have max leverage at neutral, and I accept his explanation as to why that's so.

The part I have trouble with is the idea that max leverage is obtained with aileron servo arm perpendicular at neutral (perpendicular servo arm to pushrod, and straight into aileron control horn). If you set up this way (the usual way most models are set up), then the blowback, it seems to me, would have maximum effect in deflecting the servo arm.

However, at let's say 12 degrees aileron throw and 60 degrees servo rotation you already have 5:1 advantage to the servo. With a servo of maybe 80 in.-oz. rated torque, you now have effectively 5x80 or 400 in.-oz. effective torque. So the difference in mechanical advantage presented by maybe 10 degrees offset from perpendicular (aileron horn to servo arm) is not a heck of a lot, but what little there is favors the offset geometry at neutral as opposed to the perpendicular geometry. Such is my understanding.

Hoping I can learn something useful here, and it is a worthy topic for discussion.



RC_Pattern_Flyer -> RE: Mechanical Advantage and servo setups (12/27/2005 4:29 AM)

<-- a picture is worth a thousand words...

thanks Chuck



MikeEast -> RE: Mechanical Advantage and servo setups (12/27/2005 4:35 AM)

quote:

The part I have trouble with is the idea that max leverage is obtained with aileron servo arm perpendicular at neutral (perpendicular servo arm to pushrod, and straight into aileron control horn). If you set up this way (the usual way most models are set up), then the blowback, it seems to me, would have maximum effect in deflecting the servo arm.

I dont think the issue is as much that the SERVO arm is perpendicular at neutral (or full deflection depending on the setup needs) as much as it is important that the pushrod is perpendicular to the hingeline at neutral(or full deflection for 3D) eh? If the surface is exerting a side load on the pushrod and is not pushing it STRAIGHT back into the servo arm then the whole thing is going to be in a bind at the control horn and its going to flex outward,, and you will get blowback cause then the load is transferred to the ball joint or clevis or whatever and its going to give... You want the load to be pushing STRAIGHT down the pushrod, not at an angle to it at whatever point you are wanting max holding power...

EDIT: I went back and reread what you said majortom and I see what you mean,, you are saying that by offsetting center so that the servo arm is angled out say,, 10 degrees toward the hingeline at neutral you are giving yourself a little additional advantage at neutral by "offsetting" the servo arm and cheating in towards the hingeline at neutral.. Does this have any adverse effect on the linearity of travel in both directions to the point that it matters? If not it seems like a very solid idea to use, as you put it,, "offset geometry".


quote:

Next problem I see is guys run their ATV values up really high to 140% to get maximum resolution then run their D/R values back to 30% because they have way to much travel at 140% ATV. The answer I get is well I have max resolution because my ATV is at 140%.


Wrong! You are still giving it away running your D/R down low. A little trick Tony Frakowiack taught me. Go into your servo monitor screen. The Futaba 9C, 9Z both have it. The JR 10X and 9303 both have it. Look at the bars travel as you move your controls. If the bar graph doesn't get up to the 100% mark on the graph then you are not using you radio to it maximum resolution. When I started looking closely at it I was using 60-70%...now even though my D/R value is 80% I'm passing above the 100% servo throw mark on the bar graph. Reason is I'm 80% of 130-140%....

We pay $500-1200 for a radio that has all this performance and resolution why would you give it up by having a poor mechanical setup?

I agree with what you just said,, thats the way I set the linkage up... If you have 140ATV but you have your high rate set at anything less than as close as you can get to 140 and get perfectly equal throws you havent done a darn thing. Thats why I set my highest rate at the highest possible number in the DR Expo screen (AFR on the 9z?)and my endpoint at 140 before I ever start setting up the linkages to get my high rate throws.. When I start adjusting linkages I dont touch the radio again until Im as close as I can possibly get with a 1/2 turn on the mechanicals and once Im there... THEN I make finetuning adjustments with the endpoints to get perfectly equal deflection, but that number is going to be REAL close to 140... definitely not less than about 125-130...

Now,, that being said,,, my high rate is set at as close to the max in the DR Expo screen on the 9C as I can get it... BUT when you dial down for low rates from there how do you prevent losing resolution??,,, all you can do is setup the high rate ONLY as high as you need it for your most demanding maneuver,, then you have to take what yo can get for low rate right??? If you use a dual or triple rate function you are going to lose resolution no matter what you do right?
Is there a way to get better resolution at low rates without reducing your high rate throws once you have mechanically maxed out the throws to get 140(or as high as you can get and have balanced deflections)ATV?
quote:



MikeEast -> RE: Mechanical Advantage and servo setups (12/27/2005 4:36 AM)

lol Chuckles.... you are so right...[:D]



bwick -> RE: Mechanical Advantage and servo setups (12/27/2005 5:22 AM)

Pretty sure there's not a lot you can do about that Mike.

I've got another question: does subtrim affect the movement of the servo at all? Also, how are you dialing down your throws mechanically. Are you just adjusting the arm on the surface so it's higher? Finally, what do you guys use as a throw meter?

Thanks [:D]



quist -> RE: Mechanical Advantage and servo setups (12/27/2005 6:00 AM)

Sub trim does effect servo throw a little

I go with a shorter servo arm after I max out my control horn. I don't think it matters as long as you don't get any flex in your control horn.

I have all the cheap meters on the market, the new Hangar 9 digital meter is the best. I am very careful to make sure nothing moves so I get accurate info. I get to within a .1 degree.

I know that Jerry Budd's laser throw meter is very good, but it is not cheap.

quote:

ORIGINAL: bwick

Pretty sure there's not a lot you can do about that Mike.

I've got another question: does subtrim affect the movement of the servo at all? Also, how are you dialing down your throws mechanically. Are you just adjusting the arm on the surface so it's higher? Finally, what do you guys use as a throw meter?

Thanks [:D]




quist -> RE: Mechanical Advantage and servo setups (12/27/2005 6:06 AM)

When I bought my Fury helicopter, I had Jason Krause and his building buddy's helping my set it up. When I was done, there was no subtrim in any of the cyclic/collective servos. In the CCPM helicopter all 3 servos work together for every roll, pitch and elevator input. If you had subtrim in the servos you could see that the plate the servos were connected to would not move up and down straight. It was very enlightening.

If you use a round wheel, you can rotate it to a new location until you have a hole in the correct spot



Troy Newman -> RE: Mechanical Advantage and servo setups (12/27/2005 6:11 AM)

Brett,

I use Subtrim to set the servo wheel/arm at the perpendicular to the pushrod position. I then adjust mechanical linkage to get the surface centered on the wing. If a 1/2 turn of a clevis is too much adjustment I then will adjust my sub trims a couple percent each way to get the surface perfect. Again dial it mechanically as close as possible then use the radio for small tweaks 3-4% type.

Now this also speaks to your pushrods. I use the 2mm titanium ends from Central Hobbies. This gives me the fine thread that is best for adjustment. 2-56 is next and then 4-40 is my last choice. Reason 40 threads per inch is a course adjustment compared to 56 threads per inch...Don't know the specs on the 2mm stuff but it is finer thread than 2-56.


Subtrim values will affect end points. If you have to have say 40% subtrim then your end points of travel volume will be less likely to be close together. If you get 60-70% subtrim then take the servo wheel and move it to the next spline and subtrim it back the other way to get the subtrim lower.

Another little known fact is Servo wheel splines have odd number teeth. This means that if you rotate the servo wheel 180 degs (use the other side) it will be 1/2 tooth closer or further away than the other side to being at this desired perpendicular orientation.

One of the big reasons for having ailerons servo connections perpendicular is to get symmetry in the servos output and help match up you end points better. The further off your end points are the less likely the servo are to track together. This can be seen very easily with dual elevator servos. The end points might be the same but the servos will seem to move at different speeds to get to those end points. The same thing can happen with ailerons and you will actually differential problems. So you ideally want Sub trims at zero and travel Volumes at the same exact values this means the servo are working together. On ailerons it’s very tough to see the differences but if you get the difference large enough they will effect differential setting. Hold full aileron and differential is fine but at 1/2 stick it is way off. This goes back to poor geometry and can usually be traced to big differences in travel volumes.


Dial down mechanical throw...Larger control horn like you said. And smaller servo arm. I use the wheels. They are stiffer and I can flip the wheel around and attach the connector in the exact opposite position to minimize sub trims.

On the JR servos I use the small little wheel that comes with the servos standard for ailerons and elevator. And then for control horns on the surface I use the MK large control horns. This gives me about a 3 to 1 ratio for the control horn to servo horn.

Again in 3D applications you almost have to use a 1 to 1 ratio so this means putting tons of servo power on the surface. The more servo power the better.

Another advantage to this resolution and linkage discussion:

If you have your radio travels maxed out then any servo gear slop or pot wear will be minimized. All servos have a dead band and all servos will get some slop in the gears. All servos will get pot wear even on Electric models. So maxing you linkage as we are discussing minimizes the effects of these factors.

Throw measuring devices? I can’t give you all the secrets!

There are lots of them out there. Things to look for in choosing one:
#1 Many are heavy meters that attach to the surface. If you install the meter and your surface deflects it’s not the best of choices. The heavier it is the more problems you will have matching things up.

#2 How accurately can you read and repeat the values. If you have to guess ½ degree or even ¼ degree I say it’s not accurate enough. I say I can get about 1/10th of a degree with the system I was taught to use.

#3 How easy is the meter to setup and repeat values. If you can repeat your settings its not very good. I really accurate to 10,000,000th of a degree is useless if you can’t setup the meter the exact same way twice and repeat your numbers. There is one I know of that is very accurate but difficult to setup and repeat values.


Think really hard with these design parameters and you should be able to come with a tool you can make!

I will give you a hint at a really good idea. The old guys will know what I’m talking about and might be able to help you out........ Ivan Kristensen had a little gadget.

Troy Newman



iflyrctoo -> RE: Mechanical Advantage and servo setups (12/27/2005 6:44 AM)

Hi Troy,
I have a question about the JR Digital servos.... I realize that you need to get as close as possible with the mechanical setup and then adjust sub-trims to get the last little bit that you can't get with the mechanical setup but, there is a centering adjustment available on the servo itself, located in the screw hole for the servo arm. I have never tried it but could you use this adjustment instead of the sub-trim? Would it screw anything else up?

Thanks Troy


Joe Dunnaway



Troy Newman -> RE: Mechanical Advantage and servo setups (12/27/2005 7:15 AM)

I know what you are talking about Joe.

Yes it works and very slick I might add. If you choose to do this its very delicate and can lead to stripped gears or a damaged pot. Better Know what you are doing before attempting this. I don't endorse this practice for others as it can lead to damage the servo both gears and pot.

Not all JR servos have this ability. In fact there are only a few that do this.

Troy



MikeEast -> RE: Mechanical Advantage and servo setups (12/27/2005 8:32 AM)

quote:

Pretty sure there's not a lot you can do about that Mike.

I didnt think so Bret,[;)] Seems obvious that there would be no solution to reduced resolution at low rate on a dual rate setup but sometimes I outthink myself and overlook the obvious,,, just making sure I wasnt doing that..

I try hard to use no subtrim at ALL,, Troy you are saying that at <40% you arent affecting servo movement? IF so thats good,,, I can spend less time fidgeting with linkages and save myself a couple of hours of setup time...[8D]

For balancing elevator throws I personally use an 18"-24" long straight carbon fiber tube taped to each elevator half that extends rearward until the two meet directly behind the rudder. If the points touch perfectly at neutral and throughout the full range of travel Im happy... I have found that it takes a LOT of work to get it just right but it sure works well for me. Also this will show any little flaws in a dual elevator setup because if they arent setup just right you will be perfect at neutral and perfect at full throw but they get out of whack in between... If you get the linkages dead on they will move together in perfect sync.
For angle of deflection I just use the little "clothespin" deflection gauge,, I make my own.. They are accurate to within about 1/4-1/2 degree but I must admit that the repeatablility is a little less than ideal. You have to really watch it and make sure they dont move around on you... I should probably be more particular but I tweek my surface deflection(rate) to suit me as part of the trimming process.. perhaps this isnt the best thing but works for me at my level of skill...

PS,
Bret.. PM me and tell me about the Yak... Also,,, Im hovering my T-Rex heli pretty good now, no inverted hovering yet though[8D],,, its a lot harder than I expected but its a lot of fun learning to fly a heli,, its like learning to fly all over again!



bwick -> RE: Mechanical Advantage and servo setups (12/27/2005 8:37 AM)

I gotta bookmark this thread. Great stuff [:)].

Thanks Troy. I'll definitely be coming back here when it comes time to set up the genesis or the impact (whatever comes first). Unfortunately I think it may be awhile before either one is ready [:o].

Mike: looks like I'm not the only night owl!



MikeEast -> RE: Mechanical Advantage and servo setups (12/27/2005 8:44 AM)

You should be in bed young man![:D]

Im working nights or else I would be dead to the world.. Ive got approximately 40 more consecutive 12 hour nights before this nightmare project is over!! I have been doing this(at night) since Oct 20th and not but a couple of days off period since Sept 25th...



bwick -> RE: Mechanical Advantage and servo setups (12/27/2005 8:48 AM)

I've still got over a week before I have to go back to school -- bite me [:)]

P.S. - sent that PM, check your inbox.



stek79 -> RE: Mechanical Advantage and servo setups (12/27/2005 10:47 AM)

Guys, really goooood thread! Mike, thanks for starting it, and a HUGE thanks to Troy for his secrets.... no more hints about control throw measurements???

Troy, I have a question. You said you set up your pinnacle in order to have 13 deg of aileron throws, that you use only for upline snaps. The question is... are 13 deg enough? I'm still building my first real pattern plane, and I set up my control horns to have 18 deg on ailerons. I choosed those values as compromise between enough throws and resolution and precision, but obviously now I don't know yet if these 18 deg will be enough or too much for a snap for example... Your 13 deg comes from experience with that plane or you put 13 deg in all of your planes, even before flying them?

Thanks!



Henning -> RE: Mechanical Advantage and servo setups (12/27/2005 1:11 PM)

Hi Troy,

The 2mm titanium ends from Central Hobbies have 63,5 threads per inch.


Regards,
Henning Jorkjend



Troy Newman -> RE: Mechanical Advantage and servo setups (12/27/2005 5:47 PM)

All airplanes are different so 13 degs for the Pinnacle on the upline snaps is the number I found to work best.



RC_Pattern_Flyer -> RE: Mechanical Advantage and servo setups (12/27/2005 11:08 PM)

Maybe my english wasnt so clear. Could someone post some pics with little arrows and some explanations for my tiny littlw mind to see read and unsderstand all the parallel and perpendicular and mech advatages and disadvantages. my flying is disadvantage enough without having it in my radio installation as well.

Thanks.

Chuck



Troy Newman -> RE: Mechanical Advantage and servo setups (12/28/2005 12:39 AM)

This drawing shows that servo orientation is not what our goal is but the servo wheel's relationship to the pushrod.



MikeEast -> RE: Mechanical Advantage and servo setups (12/28/2005 1:35 AM)

Right. Question, shouldn't the YES pics also show that with the servo at rest, the pushrod is NOT ONLY perpendicular to the servo "arm" or "wheel" BUT ALSO the control surface hingeline at neutral in the setup you like to use for pattern?? If the pushrod is perpendicular to the centerline of the servo at rest as shown but its not also parallel to the hingline you are losing the mechanical advantage you are looking for arent you?

Reason I ask is because if you are cutting out your own servo mounting holes and you cut them parallel to the fuse and then you line up the control horn so that the pushrod is perpendicular to the centerline of the servo arm at rest, but the pushrod is not also perpedicular to the hingeline, your geometry is not right for maximum advantage at neutral right?

Heres a couple of pics of how I understand it,, again if Im wrong its all good. This is all about learning the right way for me... I dont mind showing my ignorance if it means I(we) can learn the right way.






MikeEast -> RE: Mechanical Advantage and servo setups (12/28/2005 1:43 AM)

Wouldnt this be the Offset geometry majortom mentioned?



Page: [1] 2 3   next >   >>  

Valid CSS!




SITE MAP!   : :   FORUM RULES

© 2001 - 2007 24-7 RC, LLC, all rights reserved.
0.5136719