Mark4 5"

By otterprince on Oct 06, 2020

6  433  3

I've built a low weight 5 inch racer. I've found it lackluster in many ways so I tried something different and this build came together. It's good and fast and all that stuff I expected. It's heavy though, comes in at 360g without a HD cam and mount, however this weight does not seem to affect flight performance as much as I thought. Inertia is also nice to have, helps smoothing out everything once you get used to apply proper throttle.
First iteration of this build was completed with Emax ECO 2306 1700kv motors. Those were nice but I wanted to get some more pop to the quad. Recently I replaced them with Rcinpower Bison motors with those juicy 11mm bearings. Based on the spec sheets these should be more powerful and more efficient. Well, they aren't. Batteries start to sag on the first punch out which was never seen with the Ecos and the added weight also raises the hover point. To be far, these are somewhat faster and should be much more durable, and also adds bling for what it worth.
The new Gemfan 51477s are OK, I guess. Once you get up them to speed, they perform. On the lower end I don't really like them. Will stay with Nepals and Floppy proppys, maybe the Spitfires if I need some extra power.
First time using a Rush Vtx, and I really like it. The Truerc OCP antenna is bottleneck for now but sheer transmission power helps keeping clear video feed even behind some foliage.
My biggest annoyance with this builds is the whistling soung it makes. Only audible at zero throttle and high speeds (like diving or freefalling) and it sound like a Stuka. All cool and stuff but I am afraid that something is not OK and I cannot figure out what is going on.



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MiroslavSemancik   Feb 03, 2022  

Hello, That weird sounds...isnt it like at some throttle it is clean motor sounds and at another it is like "ironish" weird fast sound? because this is caused by quad vibrations. I had this sound when 25-20 throttle, i lowered rpm filter cutoff from 150 to 100hz and that ironisch sounds are gone. try to learn about filtering (chriss rosser on yt) and buy blackbox. You will see it there

otterprince   Nov 01, 2022 

I was thinking of the same issue. Later down the road i had to change the antenna for a stubby one and that solved the "problem", the weird sound went away. So its likely that it was some aerodynamic issue.

Oeliboeb   Oct 08, 2020  

nice color scheme!

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