I Suspect My Setup Is Hard On Servos...450L

[ic-racer]

In about 3 years this is my third set of servos for my 450L T-rex. Due to their low cost, I have replaced the servos with Align servos in the past. Although the Align servos don't have the best reputation in theses small sizes, I'm probably harder on the servos. This is what I'm thinking

1) Flying Style: mostly loops and rolls. Over and over and over and over. This is my practice helicopter.
2) High driving rate. Spirit drives them at 250hz which is their max limit for maximum performance
3) High gains. I get an occasional "shutter" which probably kills the servos, but the higher cyclic gains feel more locked in. BTW I'm flying low head speed, so the high gains are fine most of the time. Just when I do some higher speed moves I get a hint of oscillation. BTW: I'm running cyclic gain from my transmitter, so I can and do fiddle with it.
4) High driving voltage: 8V
5) Close local field. This translates to flying almost every day. So, realistically if I get a years worth of use out of the inexpensive ($35) servos I'm probably good.

Anyway, I think I'll go with the $60 servos next. Either BK or the Hall Sensor KST. I have Brushless in all my other larger helicopters, but don't want to spend all that money ($120/each) in a somewhat outdated design (450L).

Now, if I were building the ultimate durable practice machine from an Ox4....I'd fit the X-Pert Brushless Micros! Maybe this is my winter project

[ic-racer]

So, the servo that failed fried a transistor. (picture in above post) I actually have enough spare parts to build a new servo from old Align servo parts. In fact I did that. Which is to say I replaced that burned board with its attached POT and motor, with a board/motor from the 'working' spare parts box.

I tested the rebuild servo on my iCharger and 500 cycles 330Hz went fine. Speed was 0.07 sec. per original specs.

I installed the rebuilt servo and tested all of them with Spirits BEC tester and it turns out the rebuilt servo was fine but one of the other cyclic servo was sluggish. I grabbed the arm of the sluggish servo as it ran and it intermittently stopped. So, with two of 4 servos originally going bad to cause a crash, it only makes sense to replace them all, or another crash is just ready to happen.

I'll keep that rebuilt servo and the remaining working cyclic...thinking of a scale build, so they might work fine for the retracts on a 500 size A-109 Agusta which is also looming as a winter project.

[baba_yaga]

I'm running MKS. I rebuild mine due to crashing not wear. I ran the Align for along time but what i didn't like was after rebuilding they never went back to like new condition, they stayed loose. The MKS are like brand new with a rebuild kit, and they seem to have a fuseable link inside to prevent damage to the motor. So far I really like them.

[Wargamer]

You might want to try the 215MG or X12-508 at $30-35 (both KST) before you drop $60+ on a 450 servo.

I would probably go with the newer X12 if you can run 8.4v. The 215s have a great reputation and are a little faster, but only about half the torque. (They are also 7.4v max.)

The MS325 (hall effect) is certainly an option if you want to check them out and don't mind paying a bit more. (I think they are ~$50.) They are between the other two in specs: plenty of speed and torque for a 450.

Good luck!

[ic-racer]

Thanks for the tip on the MKS.

I just got an Oxy 3, so to compare that to the aging 450L, it seems like a no-brainer to retire the old bird and get the Oxy 4. The only problem is that I really like the way the 450L flies right now. With my low head speed 'inverted practice' setup it is more stable inverted flight than the Oxy 3. But the tail is all over the place with tic-tocs and low head speed.

I really should be able to build an Ox4 with the same blade size, same weight and headspeed as my well-flying 450L. Plus I'll get the 'good' tail mechanics of the Oxy4 which should give me a locked-in tail like the Oxy3.
I even looked at adapting the Oxy4 tail to my 450L...but seriously...just get the whole Oxy4 kit.

[ic-racer]

Originally Posted by Wargamer

You might want to try the 215MG or X12-508 at $30-35 (both KST) before you drop $60+ on a 450 servo.

I would probably go with the newer X12 if you can run 8.4v. The 215s have a great reputation and are a little faster, but only about half the torque. (They are also 7.4v max.)

The MS325 (hall effect) is certainly an option if you want to check them out and don't mind paying a bit more. (I think they are ~$50.) They are between the other two in specs: plenty of speed and torque for a 450.

Good luck!

Thanks for your input. The Oxy 3 TE I just built has the 215s. I had not see the x12s so I'll check those out. I like theory of running the highest voltage. Unlikely the whole industry will upgrade servo wire and connector size as current demands increase. But by increasing voltage, that original historic servo wire and connector size are OK.

[myxiplx]

Shouldn't need anywhere near that amount of servos replacing, so if I were you I'd look at what can be changed to improve things.

If your gains are high enough that you get shakes, they need lowering. If it doesn't feel as well tuned then you need to tweak other factors so it does, a modern FBL should lock in extremely well without requiring overly high gains. If it's not so locked in it may be that you need a little more headspeed.

It may be that those servos don't like being driven at 8V, dropping down to 7.4V will reduce the load considerably and can still produce excellent results. I run between 5.5V and 6V on many of my models and they 3D just fine.

Unless your flying ability is up there with the pros you can be much more gentle on your electronics and not even notice the difference in the air.

[ic-racer]

Originally Posted by myxiplx

Shouldn't need anywhere near that amount of servos replacing, so if I were you I'd look at what can be changed to improve things.

If your gains are high enough that you get shakes, they need lowering. If it doesn't feel as well tuned then you need to tweak other factors so it does, a modern FBL should lock in extremely well without requiring overly high gains. If it's not so locked in it may be that you need a little more headspeed.

It may be that those servos don't like being driven at 8V, dropping down to 7.4V will reduce the load considerably and can still produce excellent results. I run between 5.5V and 6V on many of my models and they 3D just fine.

Unless your flying ability is up there with the pros you can be much more gentle on your electronics and not even notice the difference in the air.

Lots of good points. One thing I think it comes down to is that, not only is my 450L 'very well worn' the design is outdated and not likely to be updated by Align (based on what I spoke with them at IRCHA).

I suspect by the end of the day I'll have ordered the Oxy 4. I'm on vacation so I have the day to work on this.

[jrman83]

Curious how many flights a years worth of flying equates to?

Sent from my SM-G955U using Tapatalk

[ic-racer]

Originally Posted by jrman83

Curious how many flights a years worth of flying equates to?

Sent from my SM-G955U using Tapatalk

I did not have a way to count until about a year into it (sometime around 2016), but from when I started counting, until IRCHA 2018, when I reset to zero and got a new transmitter setup, the count was 1146 flights.

I can look at the heli and see the few remaining original parts. Grips, side frames, tail drive case (some original bearings in there), CF wing and tail, battery holder, ESC holder, anti-rotation bracket, pinion, OWB and holder. Everything else, electronics, receiver, ESC, servos, FBL, bearing blocks, all components of the tail, etc. have been replaced at one time or another.

I keep a box of all the crashed components for all my helicopters. Though the 450 did its share to fill the box. Some things can be re-bent or re-used while waiting on new parts. Plus, some parts were replaced "just because" and the old part still has life in it. I did, for the first time, step on a helicopter . I knew it would happen some time. My local field is just a field, no table or anything.

Also, this is why I don't fly over people or buildings. I have not put any helicopter (besides the 150) in the ground by a flying error in over a year. Most of that box is from electrical or mechanical failure in the air or pre-emptive component replacement.