Need Advice
So I was able to get a Roban 500 size MD500 from MotionRC. I have a TREX 500...
Joe B.
So I was able to get a Roban 500 size MD500 from MotionRC. I have a TREX 500 for mechanics in it and was able to get a couple flights on it before our field closed for the winter.
If I was to replace the head with a 5 blade head, do I stay with the same blade length or go smaller to keep the load on the esc and motor manageable? For all practice purpose, it is an older TREX, pretty much stock with a HW 100a v3 esc.
8 Answers
First, consider how you want the heli to perform. Lower disk loading results in better hover and auto-rotational performance while higher disk loading results in better forward flight performance. For our hobby, I think lowering disk loading is better. Rotor solidarity (e.g. how much disk area is taken up by blade material) is a factor. You are adding more solidarity which helps prevent stall but if you leave them the same length, you add stress to the motor. Wider blades can give you more solidarity (just like additional blades) so if you can compute the area taken by the original setup and compare it to the new one, starting with identical solidarity might make the change more predictable. More blades helps with vibration (assuming they are tracked properly). I hope that helps!
Thanks for the info. Seems a bit of the old trial and error is at play . Just so I am clear, lower disk load would be the result of more blade surface area (solidarity), correct?
Correct, Joe
Joe, Go to: https://www.ecalc.ch/helicalc.php ,enter all your parameters (including # of blades, length, etc.) and it will let you know whether your motor/gearing/voltage combo is adequate for safe flying. There's a small subscription fee though:(
I’m a bit late to respond to this post, but I’ve converted quite a few 500 size helis to multiblade heads in scale conversions. For all of my projects, I’ve used equivalent or sometimes longer blades than stock. The main change that I recommend is the motor. I usually change the motor to target a headspeed of ~1700 rpm for a 5 blade head. This isn’t technically “required”, but it’s a lot more efficient than running the higher 3D headspeeds of the stock model.
As for blades, I typically look for the most scale option that I can find (thin chord). These are far and few between right now, unfortunately. I flew these on my 500 size AH-6 Little Bird with a 5 blade for years, and they worked well. The tip isn’t exactly scale, but was the closest chord wise that I could find: https://www.aliexpress.us/item/3256803607829569.html?spm=a2g0o.prod...
This is great information! Thanks Michael.
No problem! Also, I’ve typically used the Scorpion 3226 900kv motor with 14 or 15T pinion on 6S to get that headspeed
So the head is installed, phasing seems correct using MSH Brain software and the tutorial found here by Michael Kranitz https://scalehelipilot.com/articles/520d5252-f62c-4a48-a3be-484fe39.... On to painting and balancing blades. I have a Egodrift 4025 1220 kv on the way also.