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marks73
Extreme 3D
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Joined: 08 Apr 2015
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Location: Leland, NC. USA

PostPosted: Mon May 04, 2015 7:25 am
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Thanks Burgess. Just having some idea as to where to start is such a huge help. I'm sure you know that trying to change too many things at once can not only create new issues, but your not sure which change actually made the difference. Is there a connection on these helis that you haven't dealt with at one time or another? I think not. And the fact that you're willing to share that knowledge freely makes you a special person indeed. I'll check them over.
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Burgess
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Joined: 27 Mar 2012
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PostPosted: Thu May 07, 2015 3:04 am
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Mark, it may help keep this order in mind:
Main rotor, CoG, Yaw, Pitch, then Role.

#1 If the main rotor is setup correctly and
#2 CoG.....is directly under the main shaft; then
#3 Yaw.....Get the tail to hold steady; then
#4 Pitch...stop Fore and aft movement; then
#5 Role....stop or maybe reduce any Port/Starboard movement.

If only an occasional gentle right input to the cyclic stick is needed then your doing OK.

Once you've got the hand/eye coordination to lift off straight up and touch down with the training gear on, ‘tail in' try it side on ‘nose left, and nose right, eventually you'll be able to do it nose in, but no rush.


Mark: can you give the main blade pitch angles in degrees for Normal Flight Mode?

100%
75%
50%
25%
00%

And, if you can, the collective stick position when at hover, difficult to estimate when your eyes are on the heli.


I've ordered a Flysky CT6B set and a ZD720 gyro, these among other things have been on special offer. Just waiting for the firm to dispatch them.




Burgess
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marks73
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Joined: 08 Apr 2015
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Location: Leland, NC. USA

PostPosted: Sun May 10, 2015 9:15 pm
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We got it in the air yesterday and I think the wanting to roll issue was a sticking servo. Got it up about 3 feet and went through the same issues as last Saturday where it would seem to be ok and next test flight wanted to roll over. A tail boom strike while attempting to land quickly made us call it a day but during the repair and checking everything out I found the aileron mg servo was well lets say not smooth as if maybe there is damage to one of the internal gears. I don't have a spare and I haven't ordered the servos recommended for my pro build yet, but do have 4 new tower pro sg90's that came with the unidentified clone I bought last winter and am going to test and install them tomorrow.
I was considering putting the new GA250 gyro and spectrum receiver on this rebuild as well and getting used to my Dx6i. Problem is I need to know the frequency/update rate for the Turnigy S306G-HV tail servo to set up the new gyro. Can't seem to find a spec sheet that lists it. Anybody happen to know what they are?
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Burgess
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Joined: 27 Mar 2012
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PostPosted: Mon May 11, 2015 7:16 am
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Hard luck mark, the problem with any crash where the main rotor head sustains an impact, the cyclic servos require close examination of how they respond. The feed-back pots are driven by the bottom end of the output shaft, so can sustain damage during an impact.

My computer crashed, had to replace the hard drive and reinstall the whole system. Lost all my speed dials...maybe a good thing, any I cannot remember I guess are no-longer need...lol

Whether you continue with the Flysky or revert to Spectrum -probably the best option, when levelling the swashplate, use the tool to check for constant perpendicularity of the swash up and down through the central area of collective stick movement. Even spool-up without the main blades attached and observe how stable the ring traced out by the paddles is in response to slow collective stick inputs up and down through the mid-stick region. The ring ought to remain in perpendicularity to the main shaft, if not there is negative interaction.

Cheep analogue servos might seem to be the way to go when crashes happen, however, digital servos are far better, they respond faster with finer resolution and that equates to better control to small stick movements.

Servos & Gyros:
Some manufactures just don't provide frame rate and frequency info for servos. With the Turnigy S306G-HV paired with the GA250 both will react very quickly, so start with the 5 red for default servo type 1520ms/70hz, and 1 blue (no delay), if the response is too fast increase the delay.


Burgess
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Burgess
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PostPosted: Sat May 16, 2015 2:17 am
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Hi Mark, are you continuing with the Flysky FS-CT6B or have you switched to the Spectrum DX6i?

If using the DX6i, have you managed to get to grips with setting-up the Assan GA250 gyro?

Mark: can you give the main blade pitch angles in degrees for Normal Flight Mode at Collective Stick positions.
100%
75%
50%
25%
00%

and the paddle deflection angles at full Cyclic Stick positions.


As I previously mentioned, after the Flysky FS-CT6B set arrived and seeing that giantshare.co.uk have a sale on right now, I ordered components...
Motor: Keda 450H 3200KV 24A Brushless Motor
ESC: Hobbywing Platinum 40A ESC
Gyro: ZD720
Tail servo: Emax ES9257 20g Digital Servo
Bare-bones kit: HK-450MT Fiberglass/Plastic Helicopter Kit.

Also have a full set of Emax digital servos and servo programmer en route from banggood.com

So, I can then do a build and setting-up review.



Burgess
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marks73
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Joined: 08 Apr 2015
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Location: Leland, NC. USA

PostPosted: Mon May 18, 2015 8:29 pm
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Tried again with the flysky/hausler. Removed the training gear thinking it was affecting cog. Darn thing still wants to drift left while rolling to it's right side about 2 feet off the deck. I was unable to trim that out on the transmitter
I've decided to finish the pro with the new gyro and spectrum transmitter/receiver set up. I'll try to get to the pitch numbers later today or tomorrow on the hausler and am going to set it up with the spektrum to eliminate a possible transmitter issue later this week. I'm not giving up on the Hausler yet but am curious as to how the pro responds.
I purchased a used Align rotor assembly and so far have been unable to remove either screw from the feathering shaft. So far I've used a 60w soldering iron on the screws for 60 seconds and no luck. Man says he only uses blue loktite so I'll keep at it to verify the assembly. I have another new head, grips and seesaw for it, so I may just put a new feathering shaft on those and remove the other linkages from the used one.
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Burgess
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PostPosted: Tue May 19, 2015 1:26 am
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Rotor head problem:
With a hex driver in one end, try rotating the feathering shaft while still in situ, if out of true the blade holders will oscillate.
Another option, detach the rotor housing complete with blade holders, then leave the assembly soaking in acetone.

flysky/hausler:
Helicopters are strange beasties, up to a certain head speed they move horizontally in response to cyclic control, after which they will begin rotate about the Pitch and Roll axis.
Drift left while rolling to it's right side when two-feet off the deck.
If you've adjusted the cyclic (aileron) trim tab to the right to counter the left drift that will induce a right roll as you increase the collective and the head speed increases.

With the collective at the position where this drift/roll occurs, and paddles alined with the heli, from nose-on check for paddle alinement both paddles they must be exactly perpendicular to the main shaft and parallel to each other.
Check for any tendency to deflect from the horizontal resulting from lost motion.

Try this:
In Normal flight mode, with the collective at bottom stick position set the VR(A) so that the blade pitch angle is zero, and leave is set at that position. With the collective at mid-stick there should be between 5 and 6 degrees positive pitch angle. At top-stick there should be between 10 and 12 degrees.

In the Swash Afr Set CH1, and CH2, to about 45%, this will soft the cyclic response by reducing the maximum extent of paddle deflections;
adjust CH6 to set the maximum main blade pitch angel when the Collective at top-stick set no less than 10 degrees and no more then 12 degrees.

Throttle and Pitch curves try resetting to these:
Throttle curve, 00; 45; 55; 65; 95.
Pitch curve, 55; 62; 75; 87; 100.

Hopefully that HK-450MT bare-bones kit will arrive tomorrow I can then set-up the Flysky FS-CT6B and ZD720 gyro paired with the Emax ES9257 digital servo, and Emax SE09D digital cyclic servos.


Burgess
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marks73
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Joined: 08 Apr 2015
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Location: Leland, NC. USA

PostPosted: Tue May 19, 2015 7:59 pm
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I had the blade tips hit the sand Sunday when it tried to roll and now my pitch is +6 at zero collective. I'm going to go through the entire head AGAIN from scratch but it was zero and +9 at full collective with the flybay tywrapped to the blade holder on the boom.
The blade tip strike was very minor. Is it possible I have a ball link stripped and it's moving? I'll let you know what I find when I tear it down later.
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Burgess
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PostPosted: Sat May 23, 2015 6:34 am
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The HK-450MT bare-bones kit arrived on Tuesday, I'll do a build and setup review,... here's some insights.

Flysky FS-CT6B transmitter.
There is something odd happening to the pitch ranges when set to straight-line progressions:
Idle-up 00%; 25%; 50%; 75%; 100%.
Normal 50%; 62%; 75%; 87%; 100%.

With the Collective at top-stick, toggle from ID to Normal and the whole pitch [edit] range jumps upwards. I'm not sure right now why, will investigate further...Any way to prevent that from happening I set curves to these percentages:
ID.........20%; 62%; 75%; 87%; 100%
Normal..50%; 62%; 75%; 87%; 100%

*************edit extra ID deleted *********

From the second-point, the pitch angle-changes are identical, the ID still provides enough negative pitch for the early stages of learning to fly the heli, and at bottom-stick in Normal flight mode the pitch angle is zero degrees.

Here's the settings I'm using

Throttle
ID......00%; 25%; 50%; 75%; 100%
Normal..00%; 25%; 50%; 75%; 100%

End Points:
CH1 through CH6 100/100

Dual Rates:
CH 1 100/50
CH 2 100/50
Ch 4 100/100

Swash AFR:
CH 1 50
CH 2 50
CH 6 100

Pitch angle:
100...10
75...08
50...06
25...03
00...00

VR(A) at mid point.

Gyro:
Set the Delay pot on the gyro down to approx 1%.
Transmitter Gain pot VR(B) 100%
Leave both VR(A) and VR(B) at those settings;
Energize in normal flight;
Spool-up and just below collective mid-stick, change to ID flight mode.

The ZD720 Gyro isn't very fast-acting.


The all important aspect is leveling the Swash plate and eliminating all adverse interactions.



Burgess


Last edited by Burgess on Wed May 27, 2015 9:04 am; edited 1 time in total
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marks73
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PostPosted: Sun May 24, 2015 7:15 pm
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What flight characteristics would you expect to see as result of the pitch curve jump you refer to?
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Burgess
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PostPosted: Mon May 25, 2015 8:59 am
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The short answer is, none, I wouldn't fly in that condition. Excessive pitch angle from the combined collective and cyclic pitch deflections and the blades may-well stall.

Perhaps I ought to have said the swashplate jumps upwards and pitch curve jump being analogous to that.

The resulting problem being, in normal flight mode at bottom stick the pitch angle must be zero degrees and that equates to 50% of Idle Up flight mode.

By setting the pitch curves as suggested:
ID......20%; 62%; 75%; 87%; 100%
Normal..50%; 62%; 75%; 87%; 100%
prevents the adverse increase in normal flight mode pitch angles.



Burgess
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Burgess
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PostPosted: Fri May 29, 2015 9:56 pm
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Hi mark,
Check the setup of your main rotor head against data given in the Align T-rex450SEV2 manual.

Check the washout base fit on the main shaft, it needs to be very close. Check by holding the fly bar and gently twisting each main blade about the feathering shaft axis, observing the
#1 washsout base.
#2 all link-ball joints
#3 linkage balls movement on their screws
#4 side-wise movement at the mixing arm bearings.

If there is any lost motion in each linkage chain, it will be heard and the combined effect will be seen in main blade deflecting.

This is where it pays-off to invest in a set of Align linkages and the A and B links are one-piece, making setting-up the head so much less problematic.





Notice in that last photos I'm using the all plastic main rotor head. These have the 3mm feathering shafts and this provides more teeter movement and this makes for easier directional control. In the photos of the heli the rotor head came with those one-piece A and B links were fitted, some ball-joints had more lost motion than desirable and I shall swop out and refit all Align link-eyes and link-balls.

I will say that once the Flysky FS-CT6B quirks are worked around and the VR(A) and VR(B) are each set and left at one setting, the heli is good to go...and for £14.00 (sale price) an excellent entry level radio set.

Burgess
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Burgess
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PostPosted: Mon Jun 01, 2015 9:02 am
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Mark

Gyro:
VR(B) rotate the knob to find extent of rotation in either direction, then find the central position between them.
From that central index go 80% in the Head hold LED ON direction and index.
From that central index go 60% in the rates LED OFF direction and index.

Use the Rates index for setting up the neutral position for the tail rotor and clamp the servo assembly when that position is found.

Now turn the knob to the 80% head hold LED on position then energise the receiver and KEEP the knob set at that position for spool up and flight.

If the nose swings to port while on the ground during spool-up, just counter with a little touch of right rudder.

As the heli lifts-off give a little right cyclic to counter left drift. As the heli lifts it will tend to lean to the right, this is caused by the thrust from the tail rotor, looks odd but quite normal.

Rotor head:
Check the A and B links set to dimensions given the Align t-rex450 SEV2 manual A approx 20mm centre to centre, B 22.5mm centre to centre.

The B links must be dead equal. Check the flybar control rods on which the B links are fitted to. Looking at the heli from the port side, nose of helicopter pointing to your left, the ball on the control rod is situated 18.25mm from the front and 20.75mm from the back.
something like this
||----o-------||

<-----front


Also, Swash AFR: CH1 and Ch2, set both down to 45% this will soften response to cyclic control inputs.


Burgess
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Burgess
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PostPosted: Mon Jun 01, 2015 7:39 pm
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Just thought...what you've written regarding reversing channels, "Reverse was on for channels 4 and 6."

Just check, When you give left rudder does the NOSE turn to the left?

How have you got the front two servos hooked up-to the receiver,

Looking from behind the helicopter,
Are they like this?
On the right (lower position) connected to CH1
On the left (higher position) connected to CH6

When you give right cyclic
does the right servo arm go down
does the left servo arm go up
and vice versa when you give left cyclic


When you give forward cyclic
do the front two servo arms go down
does the rear servo arm go up
and vice versa when you give back cyclic


Burgess
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marks73
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PostPosted: Mon Jun 01, 2015 8:36 pm
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Yes to all.
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