It has never been flown.. therefore Im checking everything on this helicopter. The first thing I noticed was the rear pulley. There is an "UP" written on it - And this side has been mounted DOWN!! Shouldnt the rotor spin free CLOCKWISE without moving the motor (For Autorotation)? - The manual is not very precise on this, thats why the mistake happened maybe. Or am I completely wong? Please give me some advice before I pull this thing apart. The pulley sits in the core of the heli - I have to pull everything apart.. :-/

 

Nice so see you back @iggy , nice bit of kit too! looking forward to a flight report
Take care Mate
Simon

 

Hi there

I have a setup question on the RJX 700 Speed Limited.

What I have got now in there:

Kontronik Kosmik Cool 160A
Kontronik Pyro 850-50 500 KV
30 T pinion with a gear ratio 1 : 9.42

As the Konronik needs some Headroom of 20% I have two options to get my desired headspeeds.

Option Nr. 1:

Run 14S to get 2200 headspeed @ 80% on the Kosmik.

Option Nr. 2:

Swap out the motor for a 560KV, Pinion 28T (1:8.79) and fly on 12S to get 2250 Headspeed @ 80% on the Kosmik.

What do you think guys? What is the better solution for an allrounder machine and why? Flying some speed runs, big air, some 3D.

Thanks.

iggy

 

Great to see your return @iggy!

If the pulley marked UP has a one way, obviously its going to free wheel (unless the old owner connected the motor in reverse - and put everything in reverse - this is possible). So i would pull the pulley off and put it the right way up - and set everything up from there.


3d and 14S
OK power to weight is everything when it comes to 3d. If you can run 14S with smaller batteries (ie lighter?) then you will have more efficiency with less weight. This would mean a kick ass 3d machine. If you have the money and can find the right packs that suit its my opinion that a higher voltage (7s packs) are more efficient. Also with a higher voltage the C rating is NOT as critical (ohms law - i = v/r) So your batteries have to provide less current - meaning they should in theory last longer due to less stress for the same power.

 

Yeah its mounted the wrong way. I have to pull it apart.. Doesnt matter, I have time.

I think the best option would be a 14s Setup. Lets see if I find some 4400 for example

The blades are 715mm - The motor is for 800 helis.. This will be a monster am I right?

 

Hey @iggy, good to see you again on the forum!

Found a slight error, as the pinion tooth count increases the ratio value decreases, so 30t will be the 8.79 ratio.
Use a main gear count of 263.76 in MrMels calculator.
Therefore 14s with 30t and 500kv is 2600rpm @80%.
14s with 28t and 500kv is 2438rpm @80%.
12s with 30t and 500kv is 2238rpm.
12s with 28t and 500kv is 2080rpm.

The 8.79 ratio is getting pretty low, and will probably lead to a hot running motor/esc.

Also be careful running speed passes with the Helix blades, they are very lightweight and may pitch up in FFF.

The motor is powerful even though it's not the competition version. Should be plenty for 3D, hopefully the heli mechanics can hold up to some abuse
The tail ratio of the vector seems a bit mechanically low at 4.54, which should be good for speed passes but may not hold in 3D - may need some tuning.

Good luck with the maiden flight mate

 

You are right mate. I found this error on some RC pages - in the manual its correct. I agree with the numbers in MrMels. Same as I calculated. I will run 12s on 30T as the HS should not exceed 2300. I hope the tail holds, there is no other tail pulley for this model..

The Kontronik Motors can take some heat this shouldnt be a problem. The Kosmik Cool..? - Lets just try - an optional fan is allways possible.

What is the good thing about the lightweight Helix blades? How do they feel for 3D?

Thank you mate, you giving me allways good informations.

 

Done some wiring in the last few hours.. waiting for some shorter satellite wires, a fan for the kosmik and some other parts.. I like to take time have a nice day.

 

Some nice gear in that helicopter. Kosmiks are awesome - set and forget. just change a mode and optimum settings right out of the box Normally. Looking very good.

 

Mode 4 will do it. Had a Jive in my 570. Easy to setup. I have the prog unit to setup the BEC. There is a plug in telemetry system available from IISI cockpit V2 made for Kontronik Kosmik to show Battery, RPM, ESC temperature and more. Got to order that