HS 5245 is NO 65MG; I'm moving to 3400G

[rob-atl]

Interesting small crash yesterday. After lots of flying & trying different headspeeds & modes I did a flip (I sure THOUGHT I was in St1- I felt sure!) apparently in normal mode & nearly pulled it out, and had a pretty soft crash in tall grass.

THE damage was TWO of these 5245mg Servos and the main gear 162t.
Now that I'm installing the 8400G's, I'm believe I'm seeing more accurate & repeatable centering, and it sure feels like more torque to me, at least right next to center. When getting 90 degrees set up on the 5245's, I felt the servos did not respond consistently to 1 click of subtrim- often it took 2 clicks to get movement, and sometimes they growled slightly with a change of subtrim but didn't move. In contrast, all 3-3400G's MOVE a consistent tiny amount with EACH click of DX7 subtrim.

By the way, I have been a loyal HiTec user- fly my 450SE with a Hitec Optic TX, and own lots of hitec servos. But this trex 500 seems a powerful & demanding heli. This is my first JR servo purchase.

My 5245's also didn't seem to hold a perfect & repeatable CENTER before this crash while I've been getting to know the Trex 500. I would hover once and adjust servo Rods or Subtrim to get NO pitching or rolling away from hover, and a few min. later there would be a little pitching or rolling in hover. I chased it a while and then gave up & proceeded to just fly it. When I feel the 3 5245servo horns under power, I felt there was a bit more "give"/ slop? potentiometer slop? than I hoped for.

I learned to fly with my 450SE- many crashes on the 65mg and the ONLY servo damage EVER was the exterior nylon ARMS. I put the Black Plastic 82MG arms from the kit on the 5245mg's hoping to duplicate this Zero Servo Maintenence with the 500.

But, a Minor Crash clobbers 2 of 3- 5245 mg servos!
I know this is just one data point/ one crash. I hope others have better luck.

One is all bound up inside and the RX cannot move it at all, and no motor turning sound.
The other moves fine, but has about 1/16" of servo arm play at all times- not a gear tooth (the bent shaft/ broken internal case people often saw on the larger Lepton?). The 3rd servo is ok.
No broken black servo arms.

SO, while I found the 65mg a perfect match for my 450 SE, the 5245 does not appear to be a minimial-maintenence MATCH for the power & size of the 500. (So much for specs. looking like a perfect match. I guess real experience is the main guide)

How bad a crash?:
*Blades seem OK (just a nick in the trailing edge. Intengrety seems perfect)
*Main shaft & tail shaft OK
*Flybar had a medium bend- easy to straighten (but the flybar cage is pretty fragile compared to the beefy flybar.)
* 2 servos ruined
* Main gear damaged.

[Antony Konnarides]

I'm sorry to hear about your crash,
but i'm afraid to say that the 3400G will
NOT hold out any better.
I started off with 9257's on my 500's cyclic
and changed them to 3400G's as i felt i needed
more torque.
One hard landing due to one-way bearing not biting
after changing throttle speed took out my two
aileron servos.
Now I'm back to my 9257's.

[warpspeed]

Interesting post. It's funny that Hitecs are so well regarded in the plank/heli world-Guys like myself that participate in serious ground-based competition would never even consider Hitec an option. They've been junk for years and it has always been common knowledge-although some of their newer digital models are starting to show up in some high end racers.
Personally I've used them on and off in planks for years but now that Futaba has a healthy selection of cheap micro's I won't bother with the Hitecs again. Like everyone else I use the 65mg's in the littlest Rex but the centering issue has always bothered me-doesn't seem to affect anything in flight though, so what the heck. Maybe when I get better I'll feel the need to ***** about them more.
I was irritated right off the bat though with the way the 5245's fit in the 500's frame-IF you can call it "fit." Centering is just like the 65's-in other words, they don't. But I really hesitate using the 9257's all the way around simply due to crash worthiness.
If the 3400's aren't any better, then what's a poor heli flyer to do?
We may be in for a long wait....

[djames]

3400G servos don't fit in the servo holes perfectly either. You have to center them in the holes like the 5245. As long as you have them mounted properly, they shouldn't move though.

[CatchmyCorsair]

Well if the 5245's don't hold up in a crash, some one might as well try 9650's. I bet they will work great. Just look at all the Logo/9650 users.

[OICU812]

9650s work great, they fit great, geometry is good and they center nicely as well. I had them on my Logo 14s as well and they certainly can handle the disc load abuse of a small 500 rex I can assure you of that much. :wink:

[rob-atl]

Sounds like the 500 in a crash might just be hard on mini servos!
Anyone know what breaks in a 3400G? Is it 95% just the gears?

Hopefully I won't be crashing it much.

I was thinking though- Regardless of the application, seems like a metal gear servo should be designed so that everything inside is as strong as the metal gears, and let the arm outside be designed as the weak link. That was the case with the 65MG.

Anyone know about the Futaba Metal Gear servos? Do crashes break the arm, or bend shafts & damage things inside the case?

[Bjorn]

You can make the deadband arouns center a little more precise with the hitec servoprogrammer...
I use hitec 6965's on my trex600e and my xerog rush, and they both felt a little sloppy around center. So I checked on the servoprogrammer and found that the servos was not set at the narrowest deadband. After I set the deadband to the smallest possible both models felt more "precise".
I do not know the factorysetting on the 5245's, but if you know anyone with a hitec servoprogrammer it is worth a try :)

Bjorn

[duceduc]

I concur with the 3400G servos being weak. A friend of mine crashed his heli at a low inverted and stripped all three servos. The gear set is $14 a piece.

I am running 9650 all around myself.

[Pinecone]

z3650 = metal geared 3400G. :)