pvescabi

Hi.

It´s a very pleasure to write in this great forum.

My name is Pedro Villanueva, I´m from central México and my airclub is the Club Campéstre Aéreo Totolapan, in Totolapan, Morelos, México.

My question is very simple and easy, but i prefer to ask for information to the people who really knows the best answers like the people of RCUNIVERSE.COM:

I just started with gasser engines 3 months ago today. I use a Desert Aircraft 50R in a GP Sukhoi SU-31 25%, with a Vess 22 B. I flight IMAC with this plane. I use a Futaba R607 FASST 7ch receiver and a 9ZWC2 transmiter.

The plane is completelly setted in the control surfaces; mixtures, exponentials, flight conditions, etc., but, the only program that I need now is how to set the exponential curve.

I feel when the throtle stick is just over the middle, the engine is giving all the power. When I´m hovering (1/4 of throtle stick), only one more click of throtle is needed for the plane to goes launched up like as a rocket.

Can you help me to set the exponential curve?

Thanks a lot.

Pedro.

arobatx

Use a Tachometer, take a reading at full throttle. Set your throttle stick at 1/2 position on the TX, then use your multipoint throttle curve to adjust the mid stick position downward, until the RPM is approximately half of the rpm at full throttle. Leave the rest linear to begin with, and then go back to fine tune it to your feel, bits at a time. This will get your throttle feeling more linear from idle to full throttle, and get you away from the characteristics you describe.

krayzc-RCU

My Feedback: (31)

this is how it looks on my JR radio were u have to actual set each end point to the RPM u would like to see. each point is set with a tach and moving each number.

JoeAirPort

My Feedback: (41)

First I'd like to see pictures of your thottle linkage at full throttle and idle. After that I'd start looking at the transmitter programming.

Truckracer

My Feedback: (19)

I guess I'm a hard head when it comes to throttle setup. I just use mechanical differential on the throttle linkage between the servo arm and the carb throttle arm. Set it so that about 3/4 servo throw opens the carb about half way. Of course, full stick is still wide open throttle, idle is idle, etc. That usually produces a throttle feel at the transmitter that is about right for my taste. If you get it backwards though, you'll think your throttle stick is a toggle switch rather than proportional stick. Mechanical linkage is also easily changed if you want more or less differential. Just move the servo arm a spline tooth or os and readjust the linkage as needed. I find this easier than setting up a transmitter throttle curve.

krayzc-RCU

My Feedback: (31)

for me the curve makes 3d work smoother.

What it me u wanted to see the throttle set up/ servo pics?

Truckracer

My Feedback: (19)

Couldn't see a curve but I can sure feel how it works in the stick. Yes, electronic setup is probably superior but old ways die hard and mechanical setup works well for me. I can still tweek it with a transmitter curve if necessary. I'm sure guys with cheaper radios don't have throttle pitch curves available so a mechanical setup might be the only answer for them to enjoy a fairly linear throttle stick.

I still fly helis from time to time with a 9Z ..... setting up 13 point throttle and pitch curves is time consuming enough there. Don't need to do that with airplanes if I don't have to.

krayzc-RCU

My Feedback: (31)

some of the motors come on the power very quickly (ie headers, cans, tune pipes) this is were a curve will seperate the men from the boys some of the other places it stands out to me is landing i can feather the throttle to make the landing like butter with one or two clicks to bring her in. One to 2 clicks to fly out of a T-roll and start rolling things like that is what i really like to see or hear [8D]

JoeAirPort

My Feedback: (41)

I'm just saying to make sure his linkage was all good first...and then do the throttle curve. No offense, just trying to help.

krayzc-RCU

My Feedback: (31)

i feel ya we need to always check all angles and do not take anything for granted.....

JoeAirPort

My Feedback: (41)

Yep we'll get him on track.

pvescabi

KRAYZC-RCU:

Thank you!!!. Very explicit your post. I will aplicate it with the tachometer. i use a Futaba 9Z WC2 and the throtle curve graphic is very similar like your JR (very nice radio).

Sincerely.

Pedro.

pvescabi

JoeAirPort:

Take sure that I´m going to take the pictures and I´will show it as soon.


Thank you for your support.

Sincerely.

Pedro.

pvescabi

Truckracer:

Very interestant your support. I´never have heard something like this mechanical linkage...It is very nice advice. Also I´ll try it tonight in my airplane room.

Thanks a lot.

Pedro.

P.D.
The last week I was in DES MOINES, Washington, near Seattle, my fianze lives there.

gadix

My Feedback: (2)

absolutly! agree
mechanical adjusment are prior to any digital ones on the TX
if u do the Mech ADj correctly - th eminimum use of the Digi one will be needed

BaldEagel

I have found the easiest way to set up the mechanical linkage is to set the servo arm pointing straight down the throttle pushrod at fully closed (stick and trim fully back), this will give a good starting point for fine tuning the curve if neccessary.

Mike

JoeAirPort

My Feedback: (41)

Here's a post I copied from another site that I made last night. The picture of the engine is shown with the linkage at idle.

What I try to do is max out the end points and use the closest hole on the servo arm and furthest hole on the DA throttle arm to get full throw of the butterfly. I always have my servo arm at a right angle to the servo case with the throttle butterfly at 50% of its full rotation...at half throttle stick. This usually gets me a very good feeling thottle using all the of the transmitters resolution (full ATVs). It makes the throttle feel smoother.

I attached a picture of my DL-50 that was setup on my 30% Edge (going into my new 30% EF yak). This setup used Hitec 1 inch arms with the 4 holes in them on both sides. The push rod was on the 2nd hole closest to the servo, 3rd hole closest to the throttle shaft. I think my end points were not far enough out though. Only about 100/100 out of 140/140 max. I really should have drilled a new hole in the middle of two on one of the arms but was too lazy.

PS: Also ignore that 1st hole closest you see on my servo arm, I drilled that one myself. The pushrod is really on the 2nd hole. not the 3rd (and someone always catches the stuff that doesn't make sense in my posts).

Rcpilot

My Feedback: (78)

Agree with getting it right mechanically before using the radio. But we're all ASSuming he has it fouled up right now. Haven't seen a pic of his setup yet.

I try for linear stick to butterfly movement. Meaning if my high endpoint is 90%, I will adjust the linkage until my low is also 90%. I want the same throw on the top half of the stick as on the bottom half. In a perfect setup, it would have 100% throw in both directions. But that doesn't always work out. Seomtimes 100% throw is too much movement. So that's when I pull the servo horn off and move it a spline or two. Then adjust the length of my pushrod. I'll settle for 90% high and 90% low. You suffer some resolution, but at least it's linear.

It's a shame really. Computer radios make some of us lazy. Some guys have no idea how to really set up a linkage with best mechanical travel and actuation. They just dial in 25% on the low and 150% on the high. Then they wonder why all the throttle response is from 1/2 stick and below, but not much throttle change above 1/2 stick. [] It all comes back to basic modeling skills and experience. Two things that have gone by the wayside in recent years.

Call me anal........ I'll spend 2hrs futzing with a throttle linkage to make sure it's set up mechanically as good as I can get it before I even consider adjusting the radio endpoints.

krayzc-RCU

My Feedback: (31)

flyers learn something every year in this hobby. This is just one of the things some of us have down and its time to pass that info on to others otherwise you never will know as most that know how to do things are to quick to sit back and laugh or talk about the things that a person maybe doing wrong but they do not know its wrong no need to be anal in this hobby. some of us find more intrest in other things in the hobby were as others may just want to drop in and out as that is their choice. I am here to learn and help anyone I can.

JoeAirPort

My Feedback: (41)

Looks like between us all he got lots of help. That's the best thing about forums. Lot's of good ideas.

pvescabi

Yes Joe!!!

With all the comments, I have now 3 very very important tips; first.- I´m going to change all the throtle linkage and turning to carbon fimer and Du Bro heavy duty ball links, second.- I´m going to start the mechanical adjustment and, third.- I´m going to turn up the engine, and with the tachometer start to seek the middle points and teh end points of the exponential curve.

2 hours ago now, I went to the hobby store to buy the carbon fiber and the balll links. also I bought another Hitec 5645MG because I will change the actual standard gear throtle servo for one with metal gears.

Tonight I´m going to take some pictures of the mechanical adjust process.

One more time, thanks for your support!

Here you have a video of my plane.

http://www.youtube.com/watch?v=ByP92BsguC8

pvescabi

Hi my friends!!!

Well...finally and after several weeks of no flying because high winds here in central México, here is the conclusion with photos:

1.- The original linkage.- It was made of a weak glow clevis and a very thin link. That wasn´t the correct form, the result; the link is twice and the throtle answer was inconstant. At the middle of stick, I had almost al the power.

2, 3, 4 & 5.- The original linkage was replaced in the engine; by a DUBRO ball link, a more strong rod and, in the throtle servo, with a heavy duty single square link.

In the airfield, I adjust to parameters; the first.- the ATV´s at 85% in rate A, and 85% in rate B. the second.- with the tachometer showing 1500 RPM in ralenti and, 7000 in top power, I adust the exponential curve between the 13 points (photo 6).

The results was succesfully (with a Top Flite 22x10 prop):

1/4 of power at 25% of the throttle stick, 50% at medium, 75% at 3/4 and 7000 RPM´s at full.

To the final adust the throttle curve, I had to fly 3 times. The showings in land, are not the same feelings that in the air, for example; at the middle point, the tachometer shows 3500 RPM (usually 50% of the power), but, in the first flight I feel the middle of the stick so weak. Because this, in land I had to move a few of the parameters.

Again, thanks for all your suport. Without your help, I never can set correctly this.

The plane now is flying great. I had no problem with the mixes; rud to ele, rud to ail and ele to thr.

In my new proyect, I also use the information that you helped me. It´s a GP Edge 540 27% with a DL 50 cc engine. I have started with the mechanical procedure and, the next week I will testing in the airfield and set the radio.

Good bye, and see you soon!!!!.

Sincerely.

Pedro.

tailspins

My Feedback: (7)

Nice set up and good video Pedro!

john

yarom

My Feedback: (82)

Pedro, if you want to feel more power at any curve setting, just replace the Top Flite 22x10 with a real prop - a Xoar, NX, 3W, Menz, Mejzlik, or any proper 23x8, will provide better performance...

pvescabi

Yarom:

You have a lot of reason.

The Top Flite isn´t the best propeler. In the time of the test, that was the only propeller that I had.

My plane usually wears a Vess 22A or a Hawkmodel 22x8. The Vess propellers are the most common here in México because we can buy it here in local stores. the inconvenent is the cost; you can pay for one 22A or B the equivalent to 50-55 USD.

The other way to buy good propellers is asking for it by internet, oviously, when UPS arrive to home and show one invoice for the propellers and another invoice for the custom taxes that ammounts the same that the propelers, you need to call de cardiologum.

If you know about a more easy way to buy good propellers and ship to mexico, I will be very grateful with you.

Please, when you or any fellow of this forum come to México City or Morelos, let me to invite to you to have a diner and of course, to fly to our airclub.

Pedro.