Trex 450 SE and general build videos are here

[DL8698]

Originally Posted by Finless

On the link called Heli skills and setup 101 I have some of the early 450 setup vids using a 7C. Servo setup CCPM setup #1 and #2 for instance.

Also see my 10C videos as the screens there are very much like the 9C (more than like the 7C).

Bob

Thanks, Bob, I've found the 10C video, and a whole lot of other videos which I did not know were there. Thought the videos were only those on this thread. I will be downloading ALL the videos and slowly digest all of them.

Where do you find time to do anything else, like flying, seeing the amount of time you spend making these videos?

[DL8698]

Bob, I saw one of your videos (not sure if it was in this thread) showing how to lengthen or shorten a servo wire. You showed how to solder the wires to the servo PCB.

I had tried that before, and I found it a bit difficult to do a real good job due to the tiny size of the contacts.

So, what i do is, simply cut the wire, at staggered points on the 3 wires, and then either splice an additional length of wire to lengthen or remove a small section to shorten. And made very sure to solder and insulate all the joints on the wires. The stagger in cuts is to ensure that no wires can contact each other even if the insulation somewhere goes adrift.

Is it ok to do it this way? I didn't have any problems when I was flying planes with this way of lengthening wires (seldom shorten wires) but not sure if it is ok to do this for heli servos.

[Finless]

Yes it is OK to do it this way just make sure the solder connections and wires going to it cant vibrate around. One thing that happens to wires and solder joints is the solder flows up the wire a little inside the insulation and then stops. This make the wire with no solder a wiggle point. If vibration wiggles the wire it will slowly break it off at the solder joint inside the insulation! Because it's inside the insulation you cant see it happening. So make sure the wire is secured down just beyond the actual solder joint.

Bob

[DL8698]

Originally Posted by Finless

Yes it is OK to do it this way just make sure the solder connections and wires going to it cant vibrate around. One thing that happens to wires and solder joints is the solder flows up the wire a little inside the insulation and then stops. This make the wire with no solder a wiggle point. If vibration wiggles the wire it will slowly break it off at the solder joint inside the insulation! Because it's inside the insulation you cant see it happening. So make sure the wire is secured down just beyond the actual solder joint.

Bob

Thanks for reply.

Didn't know that bit about solder flowing into the insulation. Will have to take that into consideration.

[DL8698]

In the CCPM #1 video about servo arm setting, you showed the ball link attached to the arm with a nut, and also showed grinding down the stand off with a dremel.

Just a couple of questions, firstly, since the screw supplied with my ball link is so short that only a single thread protrudes from the other side of the servo arm, it is not possible to put a nut on, and holding with a single thread is useless,

Can I use a longer screw which head does not sit flush with the countersunk, but with the head protruding out from the ball link? I cannot find a longer screw which cs head sits completely into the ball.

Along the same line of thinking, in order to bring the ball nearer to the servo arm, instead of grinding off the stand off, can I install the ball the other way round, ie, with the standoff at the screw head side? Once again, there with be some part (the standoff) protruding on the end of the ball.

Will this cause interference with the link as the servo arm moves? I think the protrusion should not cause a problem, since the ball at the back of the swash has this long pin protruding that goes into the anti rotaion bracket.

[Finless]

The head of the screw wont be a problem as long as it is not larger in diameter than the ball. The screws I used way back when were long enough for the nut to go on and the screw was flush with the back of the nut. Obviously thicker servo arms, etc will make that work or not. Go with the longer screw.

As for not grinding off the standoff and trying the other side of the arm. Go try it but it still wont be straight to the swash. I would have done it that way if it worked. Grinding the standoff from the ball was the best angle to the swash for me. Different servos will change that so you have to try it yourself.

Bob

[DL8698]

Originally Posted by Finless

The head of the screw wont be a problem as long as it is not larger in diameter than the ball. The screws I used way back when were long enough for the nut to go on and the screw was flush with the back of the nut. Obviously thicker servo arms, etc will make that work or not. Go with the longer screw.

As for not grinding off the standoff and trying the other side of the arm. Go try it but it still wont be straight to the swash. I would have done it that way if it worked. Grinding the standoff from the ball was the best angle to the swash for me. Different servos will change that so you have to try it yourself.

Bob

Ok, I sure am more confident if I used a nut than merely screw into the arm itself.

As for not grinding off the standoff, perhaps you misread how I am thinking of doing it. The attached sketch shows what I have in mind.

[DL8698]

I am following your CCPM #2 video and doing the links adjustments, between the various components of the head.

As the link ends can only be adjusted by one whole turn at a time, it is very difficult to get the various parts absolutely in line. Turn one turn this way, it goes out of alignment one way, turn it one turn the other way, and it goes out of alignment the other way. Only a half turn of the eye end can get perfect alignment.

Only the first links between the servo arms and swash are easy cos i can use the subtrim.

My question is how absolutely aligned do those parts (wash out arms, see saw arms, etc) need to be? Is a slight misalignment from absolutely straight going to give problems in control, especially to a learner? If so, how do you overcome the fact that the link ends give too big a change in length with each turn of the end?

I am thinking of using half turn to get perfect alignment, and then remove the ball from the servo arm, push the ball through the eye end in the correct direction, and refit the ball to the servo arm.

[Kington99]

got my 450 flying great, took your advice and scrapped off my piezo gyro for a 401.Tache'd my headspeed at 1550 today, is this sufficient? I'm doing sport flying, got a 13T pinion on and some slightly soggy packs, is it worth swapping up to 12T? will it make any difference if I'm not flying 3D?

[Finless]

I doubt you had 1550 as that is lower than even a 90 sized heli. A 450 probably wouldn't lift off the ground 2550 maybe?
Stock motor and 13T pinion with 100% flat throttle curve should be close to 3000 head speed.

What are you using to tach the head?

Bob

[Jasmine2501]

Probably it's only counting half the revs - giving 3100 rpm, which is about what you would expect.

[Finless]

Thats why I asked what he was using to tach. With a skytach you have to double it.

Bob

[guitarherowanab]

wait....with a model avionics skytach you have to double what you get for your reading? then my raptor headspeed is about 3700 rpm's........and my 450 would be about 5200.

i musta read that wrong.....i hope!



rob

[Patriot996]

I tached my 450 SE with a Model Avionics SkyTach and got a head speed of 2550 RPM. I need to double that? Just curious.

[Kington99]

i was using the iphone heli tach, readings were actually 1454, 1442, 1433

also apologies I believe it's an 11T I've got on there, I'll tach it again next chance I get and then try a different pinion, i take it low 2000s is the area to aim for?

[Finless]

If you are using a skytach older models had a max RPM of like 2400 or something. The new ones I forget what it is now. But if your head speed is over what the tach can read then what you do is halve the speed on the tach.

So for instance if you believe your runing say 3200 and the tach only goes up to 2800 it's not going to read right. So set the skytach to like around 1500 and adjust until you see the blades stop and then double the value in the display. In this example of 3200 you would see 1600 in the display when the blades stop and your actual head speed is 3200.

Kington99, there is no way you are flying a Trex450 with that low of a head speed. So something your doing is wrong.

Bob

[guitarherowanab]

thanks for clearing that up, bob. i made a post about that in another forum, i think.....i was getting a reading of like 1300 or something on the 450, and someone said that there are 2 "resonances", if that is the right word. so i was actually at 2600.....


rob

[Kington99]

right, had another go at taching tonight, had an awful lot of trouble getting the iphone app to register the heli at all, got a handful of readings of 1483 but more importantly one of 2093, does this sound ballpark correct? not sure why I'm having so muhc problem, will go over to the helitach thread and discuss

[Mik3Lit3]

Didnt want to read through all 100 pages but had a question. Great vids btw. Have helped alot in my first ccpm chopper when using the bubble guage, i have it level at center, pitch up or down, dont make any adjustments, return to center and the guage is way off level. Any ideas on what may be causing this? Everything else including pitch is aligned up tight at the moment

[Finless]

It's slop in the system and expected. I showed the bubble level method for completeness but on 450's due to slop the bubble does wander. You really don;t need to do this procedure unless you want total perfection which is hard to get when there is slop in the system. If you want to, the trick is to wiggle the paddle and find the neutral or "in-between" slop position at each pitch location.

Bob