Bizarre servo behavior with Exi 450 SE!!!

[akent]

I did some research into the Towerpro SG90's.
These are extremely similar to an HTX servo and also a couple of others. There are differences, though.

These are all power hungry and are very sensitive to power supply noise, it turns out.

Before I did the 'static mod' to the boom of my heli, I noticed that the HD2216MG servos that I plugged in, in place of a couple of these SG90's did NOT go nuts, when the remaining SG90 still did.

In my opinion, these low end servos have no place in a helicopter, even if it is low end itself. Even a low end heli crash will cost more than these.

My recommendation for everyone is please do not cheap out on servos.
I have ordered some of the HD2216's for the 450SE to replace these junk Towerpros.
Kent

[ranben]

Hey Kent,

Have you got a link for the HD2216 servo's ?

Havnt been able to locate them.

Thanks

[Solitaire]

ranben

Not sure you're all that receptive in placing another order with HobbyCity, but...

www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=6607&Product_Name=Digital_high_torque_bearing_servo_15.7g/2.2kg/.09sec

[ranben]

Thanks Sol,

I will probably buy from them again as long as it is something I dont need right away. Otherwise, I would rather pay more and get it quicker.

[McKrackin]

These are excellent for a 450 size heli....

www.helisreadytofly.com/product_info.php?cPath=2_32&products_id=19&osCsid=69bc847e937f1be7b368458b12725956

[akent]

You're right Mckrackin.
The HS65's are pretty much the defacto standard for Trex's, from everything I've read.

The cool part about the HD2216MG's is that they are digital and have metal gears and are way cheaper than the Hitec analog HS65.
The HD2216MG costs only a couple more bucks than replacement gears for the HS65MG!
Kent

[19000rpm]

Look forward to hearing about those servos akent. Getting ready to order some new ones for spring when I start to really abuse the heli servos.

Happy landings

[McKrackin]

I use Align DS610 and DS620 on my 500.

The 450 would be best served by DS510 and DS520.

At 60* in 0.07 seconds there are none faster that I know of.
www.helisreadytofly.com/product_info.php?cPath=2_31&products_id=11&osCsid=69bc847e937f1be7b368458b12725956

[Solitaire]

Thanks Kent. Will get a couple coming when HC gets stock on batteries.

Here's another one that looks promising with great speed.

www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=8511&Product_Name=MKS_DS480_Digital_Servo_1.85kg_/_.068sec_/_10.9g

[akent]

Mar 15, 2009 12:36:46 GMT -6 19000rpm said:

Look forward to hearing about those servos akent. Getting ready to order some new ones for spring when I start to really abuse the heli servos.
Happy landings

19k, I'm already running them on the tail of my Exi 450SE and the Exi T450 CF. They work great with the XM G401B gyro. Rock stable and very fast to respond to gyro input.
I have about 8 batteries through one of them though, so no long term life, but so far they are great.
Kent

[akent]

Mar 15, 2009 13:18:24 GMT -6 Solitaire said:

Thanks Kent. Will get a couple coming when HC gets stock on batteries.

Here's another one that looks promising with great speed.

www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=8511&Product_Name=MKS_DS480_Digital_Servo_1.85kg_/_.068sec_/_10.9g

That thing is FAST! That's an odd hump on it's back...

You know, I have read quite a lot about tail servos on these helis.

FAST is apparently the name of the game with tail servos, so everyone says.
The interesting thing is, that these HD2216's are really only 0.13sec/60degrees, so are not that speedy. This is according to the MFG datasheet and the box they come in. I think the website is wrong, or they somehow tested faster than the mfg states.
BUT, they are digital and respond very quickly to smaller inputs. I am still running zero delay in the gyro. The tail is rock stable.
I really think it's all about speed to respond to gyro inputs. The gyro is never going to be giving out large movements, but a whole lot of very small ones. How fast can it respond to the small ones I believe to be the key.
Maybe generally faster servos to move 60 degrees are faster for smaller inputs, too. Maybe that's why people think that way.
All I know is these are not as fast as advertised, according to the mfg and box, but they work extremely well.
And, they sound and appear as fast as Xheli's DMA016 digital servos that I have all around the Exi 450 Squadron. Xheli claims 0.09sec/60 degrees on those, too. Those also work great for the tail. That heli has an Esky 704B gyro. It's nowhere near the gyro the G401B is, though!!
Kent