I just read an article thar Ron from Ricks Heli's wrote on throttle up and he says to be sure to set the ATV at 100% on both sides. This is contradictory to what I have read in Rays manual where he says to use between 55 and 70% ATV's and to use an inner hole on the servo and an outer hole on the carb.

I just spent some time setting my heli's up like Rays manual said, then I read this article from Ricks and am kind of confused.

How do you all set your throttle linkage up? Huh?

I would say Ray's mothod is better. It allows you to mechanicaly increase your throttle setup's
speed. I too just changed a few things after reading Ray's book and it is working out very well.

I'm gonna get beat up for this one, but here goes.

What's the diffrence???

All that you will see here would be a speed change with the throttle control. Right!!!

I guess you could speed up or slow down the throttle response and fine tune it to match you collective response with this method. But I don't see any need to worry about ATV's other than making sure that your carb reached full closed and full open.

I try to keep my throttle servo matched (close anyway) to the speed of the collective servo.

If someone has a better reason, I would like to here it...

Jeff



Another note: This would be totally related to how your throttle servo speed is matched with you collective servo speed. Most people would need to speed it up with linkage, others (I'm sure someone will have a .... say ..... 9253 servo on the throttle ) and would have to mechanically slow it down.

This could be a real interesting thread(which is good)!
I run between 80% and 100 % on my throttle atv's and try to keep the ball on the arm out as far as it is on the carb.The thing I want is, to have the carb half open, at half stick,or in the"hover range" somewheres as suggested by the engine mfg for a reference point before I set up my throttle curve
The other thing i set up for is,the travel of the throttle, matching the speed of the collective,
I want both to hit top or bottom at the same time.In other words,I want the same transit times on throttle and collective,this way the engine never has to fight to catch up to pitch changes,both positive and negative,and the collective to be at half its travel or half stick when the throttle is halfway open(in normal mode)
The setup in rays may be good for other parts of the heli,but considering theres no load on the throttle linkage,is why i keep the balls out the same lengths on the arms.Running higher or lower atvs on other points of the heli for better resolution and keeping the torque rate of the servo is something I go back and forth with depending on what I'm setting up for,either contest or 3D/sport flying.I say theryre both right,it all depends on what your personal preferences are.....
MD

Hey Hitch-Hiker,

Here is another idea that will be hit hard!!!

Instead of playing with all that matching of curves to make your throttle keep the head speed constant, put in a governor!

Futaba makes one that really works good.

Seriously though, Curtis in his book recommends that you should use as much of the servo throw as possible. I believe that his theory is that if your servo has 1024 bits of resolution over its full range of travel, then you want to use as much of that travel as possible to have the best resolution and precise control. For me personally, as long as it hits both ends I don't think I would know the difference??? Guys that are really into precise manuevers might have a different idea.

Level 456, here we come!!!

Ken

<<it all depends on what your personal preferences are...>>

There it is. Like anythng else on these infernal machines, the throttle set-up can be done many ways.

The reason for the "concentration" on ATVs is due to computer radios. Back in the days of pot radios, the thing to do was "box up" the throttle linkage- IOW, imagine a parrallelogram (sp?), the four corners of which are the ball on the throttle arm (Point A), the ball on the servo arm (Point B), the center of the servo output shaft (Point C), and the center of the engine throttle arm (Point D). The distance between A & D are the same as between B & C; the distance between A & B is the same as between C & D. At 50% servo throw (half stick), the throttle barrel is half open, and everything is ninety degrees to each other (a perfect rectangle). This can be a real PITA to acheive; but it was worth it. I still do it this way.

The idea behind all of this was to eliminate differential throw at either end of the travel, so you ended up with a smooth engine response. Computer radios and adjustable ATVs have made this easier to do, but too many folks are just punching buttons until they get, as stated above, a closed throttle at one end and an open one at the other. It's not that simple. You might get lucky doing it this way, but if you have 70% ATV at one end and 125% on the other, your engine response will be FUBAR and your throttle curve will look like a snake.

Nothing is graven in stone. People like to use whatever Curtis is doing as an example. Curtis, for many years, preached the "box-up" method described above. Now, I hear he is running a longer servo arm (thus losing the "perfect rectangle").

Governors as a solution? Sure; until it pukes on you. Then what? If you don't have a good set-up as a back-up, you've now got a serious problem. Technology is nice; but nothing can take the place of a good mechanical set-up.

Steve

P.S.: I just read Ron's piece on his site. His drawing is better than my words...<G> But that's what you want to achieve. I also think that if you miss the 100% ATV goal, no big deal- AS LONG AS BOTH ATVs ARE THE SAME.

Well, consider the case where you dont have a GV1 but you do plan
on using cyclic->thr. mixes but dont have a 9Z so your Tx will overthrow
the throttle servo when at max throttle and you give it some cyclic.

The common solution is to max out the subtrim on the throttle servo
so thhe servo cannot move anymore. Then set the servo arm and the
throttle arm so that they are at about 45 degrees (I've noticed most
carbs are actually +/- 42-43), the high ATV to 100 and the rod the
right length. The midpoint will fall to 90 degrees (a Good Thing). However,
when it comes down to low throttle (cut), you will need less than 100 ATV.
Usually, about 80-85. My statement is "So what". The only time I use the
low side is starting and spooling up. In any flight mode, I'm only interested
in the high side.

The important thing is to look at the angles involved and if you have
equal throws on both sides of 90 degrees, you can play w/ the arm lengths
as you desire. You can have a parallelogram or a trapezoid, it doesn't
really matter but each will give a different feel but the setup is mechanically
true.

When you use unequal arm length, you get a multiplication effect which is
OK (note how most mfgrs use different effective arm lengths when doing pushpull). When the arms aren't parallel to each other, you get mechanical offset (due to the sine/cosine of the difference in arm angle).
which is a Bad Thing.

<<...if you have equal throws on both sides of 90 degrees...>>

Ah; but will you have that with one arm longer than the other (trapezoid)?

By definition, a trapzoid is an equilateral with two parallel sides. To get ninety degrees at 50% servo throw/throttle opening, the servo arm and throttle arm must the two parallel sides. This means that the length of the actual pushrod will NOT be same as the distance from the servo screw to the center of the throttle arm; along with the longer servo arm, I don't see how you're going to get equal throw on each side of center. Going the other way (offsetting the servo arm, making the pushrod parallel to the plane from the servo screw to center of throttle arm) would be even worse, I think (that cosine effect Howard mentioned).

Does any of this matter? Good question. The first "trapezoid set-up" I just described above is what Bill Meador observed on Curtis' ship not long ago (for those of you who that matters to), so obviously it works to some degree.

All I know for sure is, after I began using the "boxed" throttle linkage set-up, all my throttle and engine response problems went away. This certainly isn't the only way to do it, but it is a way, and it works admirably if you take the time to do it right.

Pardon this comment; but discussions like this always remind of something the late, great Don Chapman said;

"Too many guys are trying to get the max out of their machines, when they should be concentrating on getting the first ten percent right."

I know, Hivoltage was not looking for the latest whiz-bang 3F trick; just some basic throttle set-up info. Many times, though, these discussions deteriorate into the esoteric, and the poor newbie who just wanted to know what to do is left shaking his head...

But no fair, Howard, about the servo overdrive thing. That was a cheap shot at we poor JR guys...<G>

Steve

actually, its a quadrilateral, not equilateral.

In a severe blond moment, I was thinking of the trapezoid affect
as it relates to a full push-pull type configuration, not a 'pinned' type.

Anyway, I agree. I use the box method.

<<...quadrilateral, not equilateral...>>

Yup; my mistake.

<<...severe blond moment...>>

Back when I had hair, it was brown. I know what you mean, but for me these little anomalies are fast becoming "senior moments"... :-(

Steve

This is a nice thread!!! Although I did not understand most of it...<ROFL>

Anyhow, I see Mr. Lund has done it again. <G> His isometric drawings are very nice and seem to show what most of us who don't have engine problems are doing to the masses. Very nice and easy to understand.

I run a long throttle servo horn on to match the outer hole on the engines carb arm to keep all running square.

Getting the throttle right is really very easy to do once you look at that drawing. I agree with you Steve, it's better than words. He could also be onto something with the wah-wah's too...

So, what you all are saying is that the way that Ron explains is probably the best way to go. Is that correct. Thanks for all the responses.

<<...the way Ron explains it is the best way to go...>>

Not so much "the best", but definitely the most fool-proof way to assure a good throttle response. Just don't get locked into the 100% ATVs. As long as BOTH ATVs are the same and at least 70%-80%, you'll be okay. More is better, of course, since more ATV means better servo resolution. And don't be afraid to change the "size" of the box. If you cannot get the ATV rates you want with the balls on one particular hole, try another one.

A quick tip: it is generally best to use the outer hole on most OS throttle arms, and match the servo arm to that. Just remember that this is the ONLY area you have any "fudge factor". The pushrod length is dictated by the distance from the servo output shaft to the mixture screw. Since both engine and servo are permanently mounted, there is no adjustment available there.

I've been talking with a few folks about the "trapezoid" set-up and, like I suspected, there's more to it than meets the eye. This definitely is worth more research- after I finish the OTHER half-dozen projects I've got going on...<G>

Steve

Thanks for all the good answers. I think I got my question answered.

some people like having a little faster servo on their throttle so that it increases the throttle just a bit faster than pitch but i guess with a good throttle/pitch curve you wouldnt really need that.

No; but it can't hurt. For sure, you definitely do NOT want throttle response lagging behind collective pitch changes. The more aggressive one gets with his machine, the more important this becomes.

Steve

Because of this thread....

I just bought a 9253 to put on my >Throttle<

Figured that since it was a ccpm fury with (3) 9250's, having the throttle a little faster would be a good idea... besides, the 3 servo horns are absolutly huge on the collective/cyclic servos and I would never be able to get the throttle horn that big and could not match the speed with any mechanical adjustments.

Would have never given it that much thought before this thread!

Thanks Hivoltage!

Jeff

Hey, thats what Iam here for....to help you spend your money.