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Hi folks,
to celebrate this new SJM forum I post my review of the 430
As you may know I am a big SJM fan as I started heli flying with an sjm400pro a bit
more than one year ago.
So, I had to sell my good old SJM500 and move the electronics to the new SJM430
It is equipped with top electronics to guve the best out of it.
3326 1210 Scorpion Motor + ESC Scorpion
S9650x3 + S9257
AR7000
and AC3X (yeah baby)
So I recieved the box very well packed and when I pulled out the parts I said to myself:
wow they are even better finished then on the 500.
There are many improvements versus the 500:
A tougher flybar (3mm and nice paddels) which is super freely moving
A bigger tail assemby (4m axis 210mm diameter) with integrated chinese weights but may be not with enough pitch
- thrust bearings on the main rotor blades and on the tail blades
- a bigger tail boom
- motor on the top
- adjustable servo mounts covering mini to standard servos with 2 or 4 screws.
- Brilliant accessibility . belt, maingear, pinion, motor... everything can be
changed without removing a single screw of the chassis. A dream for a serial crasher like me.
and some bling bling that weights 60g (but youget used to it)
It comes it 3 main assemblies but, I removed, loctited and screwed back all head and tail screws (chassis screws were already secured on mine)
I mounted all together very easily with no issue.
Everything is perfect, so It will be hard to keep my objectivity!
But installing the servos showed some troubles. There are 2 possible main axis positions. A high and a low one
(gentle or more 3D, 1cm difference).
for the high position the servo-swashplate rods are too short and for the low position, the swashplate-mixer rods are too long ... too bad especially because on the 500 everything was right.
Well, I had some longer rods and mounted them.
Next trouble was some vibrations on the tail fin while I wanted to spin up the tail rotor to check the efficiency of the chinese weights.
The big tail boom twists and torsionally resonates with the tail rotor. I had to balance the tail blades with some tape on a trial and error basis to get rid of these vibrations.
everything is so rigid on this heli that it forgives nothing.
But I wasn't finished with vibrations as during the first hovering in my parking lot, on concrete, The heli be× to chicken dance violently during spool down.
So I unmonted the main shaft (4 screws and 4 ball inks that's all it takes!) and I balanced the whole head with the blades mounted on.
1 1/2 inch of electrical tape was needed and the subsequent hovering was very nice and smooth.
The new head is very rigid as the new blades holders are equipped with thrust bearing and thus it is not forgiving any unbalance like a damped head would.. A true racing machine.
So let's do the first real flight with the flybar. (+/-12° collective and +/-7°cyclic and 2600rpm (100% 13T pinion))
Nice!!!, plenty of power despite my squeezed batteries (60 cycles 2200 21C zippys), very accurate and stable with the bigger flybar but also a lower flight speed and less nimble. it flies much more like a rex500 now.
The previous sjm500 was faster and more agile but less precise than the rex.
But after 3 minutes, it started to make a wowowowowow
and before I even could land, the whole thing exploded in midair and
fall like a stone from 15-20m height!!! A rotor blade with the whole blade holder flew away!!!
As I picked it up and I could see that the feathering shaft securing screw was not tight enough (although loctited). The feathering shaft unscrewed then gradually (wowowowowow) and teared of the 2 last threads.
So be very careful and tight these screws much more then you would. And put also some loctite directly on the feathering screw! this is very important!
Well from there, we became friends again because the kiddy had
almost nothing despite his fall from 5th floor.
main shaft bent by 20 degrees (I never saw that), a flybar in spiral, 2 servo gears , the main gear ruined, a broken ball link, and a little painting gone on the canopy ... The 500 would have suffered more!
Considering the shape of my flybar, I considered the flybar test successfully concluded (I made a real crash test uh?)
and moved to the dark side: Flybarless. As SJM has extended the blade control arm is even easier then before. One has just to slide the arm
more toward the center and connect it directly to the rod that
comes from the swashplate. that's it 2min!
And the first flight was great. The speed is back and rotate rates too. But the surprise were the settings! With the 500 and the vbar, I never managed to get rid of pumping in fast forward flight, so much that I sold it to take an AC3X with which I managed to get rid of this pumping only by lowering the I gain to 30% (default is 50%)
With the 430 I am able to increase the I gain to a full 80% without pumping!
So the stabilization is also much more efficient and there is never any need to correct any drifting flight attitude! Awesome!
The biggest clou is the vertical descent in it's vortex! usually it always slides to the side. Here it is moving down STRAIGHT without any input on the sticks!
Here the 4th flight video with my senile zippy 21C batteries:
http://www.rcmovie.de/video/eb8ebb94ebc82f0fac2f
I still have a problem with the under-sized belt:
I found that the max pitch of the stock tail was on the low side,
so I mounted a longer tail shaft to reach insane pitches.
But due to this high pitch the belt is slipping when I request simultaneously full pitch and full yaw to the right (worst case)
So I have ordered bigger pulleys and a wider belt (20$)
tail pulley
front pulley
Riemen
I will report how they'll fit...
regards
Marcel |
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发表于 2009-2-18 15:27
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