Help! 3.7g servos VS 5g servos

[Jo's squadron]

So I am thinking of getting some 3.7g servos for my minis but are they strong enough? Here is the amazon link.
Thanks in advance for the replies.
https://www.amazon.ca/dp/B0DCP8NXK6/

 

[NickRehm]

They probably have enough torque for anything sub-400g. In my experience they are much more delicate and prone to stripping out in a hard landing, but that's kinda just the nature of the smaller servos

 

[quorneng]

The choice of a servo depends entirely on the weight and speed of the plane and what you expect to do with it.

As an example the scale foam 50" span Antonov AN2 shown in my Avatar uses just 3.7g servos! One for each aileron, elevator and four for the flaps. Its light flies slowly and is definitely non aerobatic so no problem.
It does however pay to ensure the control surfaces and linkages are free moving and geometrically correct. It is worth noting that small servos need less power (the stall current of most 3.7g types is only 0.5A) so giving the BEC an easier time and reducing the likely hood of an Rx "brown out".

Obviously if you intend to do violent high speed complex manoeuvres it is important the control surface move regardless of the aerodynamic load so a powerful servo and robust linkage becomes important however you do have to ensure the servo power supply is adequate.
Its one thing if the load causes the servo to stall and not move until the load reduces but quite another if the servo amp drain causes the voltage to drop meaning the Rx dies completely until something changes by its self!

 

[leaded50]

if yoy check specs you find this: Normal plastic type cheap ones:
3.7g servo - torque :0.6 kg/cm at 4.2V
5g servo - torque:1.0 kg/cm at 4.8V
But as said here it all depends on the plane, and as said, esasier for the RX

 

[Jo's squadron]

Thank you all for the replies! I like to fly rather hard... like I try to hover half of the planes I build😂
But would it work on a mini sportster on an F pack on 3S for example?

 

[L Edge]

Thank you all for the replies! I like to fly rather hard... like I try to hover half of the planes I build😂
But would it work on a mini sportster on an F pack on 3S for example?

Actually, in order for a plane to hover, it is the proper placement so that there is always a good airflow to control roll, pitch, and yaw. Heck, you can make a transport hover with just standard servos or lightweight ones. You just need to know that trick to accomplish it.
If you would like to see the video, let me know.

 

[telnar1236]

I bought a pack of these servos a while ago and so long as you're not traveling at 70 mph, which it doesn't sound like you will be, they should be fine. Not very strong, but strong enough. However, they're not very precise, so if you need precision to fly 3D, these servos might not be ideal for that. The centered position moves by a couple degrees (at least in the ones I bought a couple years ago) every time you move the stick.

 

[Jo's squadron]

I bought a pack of these servos a while ago and so long as you're not traveling at 70 mph, which it doesn't sound like you will be, they should be fine. Not very strong, but strong enough. However, they're not very precise, so if you need precision to fly 3D, these servos might not be ideal for that. The centered position moves by a couple degrees (at least in the ones I bought a couple years ago) every time you move the stick.

Thanks for the input! What do you mean by every time you move the sticks?

 

[Jo's squadron]

Actually, in order for a plane to hover, it is the proper placement so that there is always a good airflow to control roll, pitch, and yaw. Heck, you can make a transport hover with just standard servos or lightweight ones. You just need to know that trick to accomplish it.
If you would like to see the video, let me know.

Sure I would like to see the video!

 

[L Edge]

Sure I would like to see the video!

If you really want to learn all about hovering and 3D acrobatics, there are 3 main things to be aware of.

1) Use digital servos, which give you better response and more accuracy.
2) You need the proper dia and pitch prop to give you bite and also braking action.
3) Proper location of the battery within the plane. Especially with the transport which I had to evaluate.

 

[telnar1236]

Thanks for the input! What do you mean by every time you move the sticks?

Like if you give it some up elevator, the elevator keeps a bit of up deflection even after you release the stick and if you give it down elevator the elevator keeps a bit of down deflection after releasing the sticks. Could be an issue with the gears or more likely the potentiometer isn't properly secured or the electronics aren't very good.

 

[AIRFORGE]

It's kind of like having a little too much slack/play in a car steering wheel.

 

[Jo's squadron]

Hmm... ok thanks for the replies guys! I am not so sure if they are worth it any more...