trex 450 wont fly

tomstr65 · Posted: Fri Oct 03, 2014 12:15 am Post subject: trex 450 wont fly

I have a trex 450..i bought it 2nd hand..i am doing my adjustments on the swashplate..started with turning on i think the idle up! I think anyway removed all my arms.locked the tx at 50..adj all servos via tx..leveled everything now when i try to fly will not take off?? Mid stick zero pitch full cant get 90..inless i adj the blade??

tombo242 · Posted: Fri Oct 03, 2014 3:51 am Post subject:

I do not understand "Mid stick zero pitch full cant get 90..inless i adj the blade??"

If your blades have positive pitch and sufficient rpm, then the heli MUST fly. Maybe not well but it should lift. Have you checked the pitch settings at high & low stick? Seems like this could be a solution.

Tom.

tomstr65 · Posted: Fri Oct 03, 2014 9:28 am Post subject:

[quote="tombo242"]I do not understand "Mid stick zero pitch full cant get 90..inless i adj the blade??"

If your blades have positive pitch and sufficient rpm, then the heli MUST fly. Maybe not well but it should lift. Have you checked the pitch settings at high & low stick? Seems like this could be a solution.

Tom.
I guess i didnt explan better.if i measure my pitch at the lowest point and do adjustments,then midpoint,then full i still cat get full 90 percent..i think i found the problem..my swash was to low?i think i have my links straight...and i dont know if i need to use my throttle gear switch is for..im a newbie so dont no anything yet...thanks

tombo242 · Posted: Fri Oct 03, 2014 5:29 pm Post subject:

Hi tomstr,

You WILL need a swash leveller. Instructions follow:

(Finless Videos on CCPM Set Up are good here. Check on Youtube)

First remove the helis' blades & head, and disconnect 2 motor leads or make sure that "Throttle Hold" is working.

Start with sub-trim. It's not the trims next to the sticks on the Tx, you have to go into the menus to get there.
On the DX6i you'll find it in the "Adjust List" menus.
Although all 6 channels are listed here, we are (for mid-stick swash leveling only) interested in the AILE: Aileron, ELEV: Elevator and PITCH:
Pitch in this case, is actually one of your Aileron servos, the one on Starboard - Right-hand side looking from the tail or the Upper Servo of the rear pair.

The purpose of Sub-trim is to alter the center point of the servo.
N.B. First power up the heli select 'Idle up' (F Mode) on DX6i and set the throttle to mid stick.
When setting up a servo you must always first remove any sub-trim to put the servo at its natural center to the Tx,
and then try to get the arm as near to 90º to the link rod as possible, often one spline will be nearer center than the other, use that one,
if it out by the same amount either side then use either. You get this as near as is possible on all servos.
Then bring each to 90º by adding or subtracting sub-trim. You should only need a very small amount of sub-trim

Your swash should be at the throttle mid-stick height at this time i.e. at the center of the range of travel up & down the mainshaft.
If not, it needs resetting for height. Once at throttle mid stick with the swash reasonably level. We fit the swash leveller.
Choose the link which looks about the right height for center and screw the other links up/ down to match.
I like to use the Elevator as master and adjust the Aileron (left) and Pitch (right from tail) to match. I find them easier to adjust.
Once you have all 3 links matched as near as the link adjustment will allow, it's time to use the sub-trims to take out any very minor differences.
You've now made the last sub-trim adjustments on the heli.

Your swash is now level at throttle mid stick, but servos are never matched and each will move a very slightly different amount for the same Tx command.
We have to match the three servos.

Move the leveller out of the way and move the swash to the min height by moving the throttle stick.
Now refit the leveller and recheck for level. If the swash is level it will be amazing. If not we have to use the Travel Adjust on the "Adjust List" menus.
This allows us to set the range of movement at each end of the servos' travel.

Now repeat at max stick. You should now have a swash that is perfectly level throughout its travel. If you find that the heli drifts forwards or sideways do not use trim.

First check very carefully the balance. When held by the flybar with it at 90º to the fuselage.
Looking from the side, the mainshaft should be absolutely upright and the heli perfectly horizontal.
Make sure that you have a known true vertical edge to line it up against by eye as you hold it by the fly bar. This will check the fore/aft G/C position.
If not correct then you must shift some weight around to balance the heli.

Now repeat with the flybar in line with the fuselage looking from the front and back. The main shaft should be vertical and the heli upright.
If not rebalance side to side until it is correct.

Unless the G/C is exactly under the mainshaft the heli is going to drift towards it and will seem to need a click or two of trim.

P.S. I'll tell you why no trim to balance an out of balance heli, apart from the rudder,
any trim will be reversed when inverted and make the heli twice as hard to handle so your very first invert is likely to be a quite spectacular crash.

Hope this helps - you have not picked an easy heli to set up first time.

Tom.

Burgess · Extreme 3D Joined: 27 Mar 2012 Posts: 1101 Location: Wales

Hello tomstr65 and welcome to the forum.

A couple of questions:
Which version of the T-rex 450 do you have?
If your not sure post a photo and we'll have a look.

Do you have a manual for that version?
If not, down-load a pdf for your specific version.
The manuals give the lengths at which to set the cyclic link-rods.

Seeing how it's secondhand, there may-well be some play in the ball-links, if literally any than replace the full set of genuine Align link-rods and balls.

Also check the washout-base for teetering on the main shaft.
If your in the UK, then align-trex.co.uk are great for spares.

Great write-up there Tom, I would add:

A couple more checks to do with leveling tool on the swash.

#1 Move the stick to full up position. The top of the tool needs to aline with the bottom of the drilling at the top end of the main-shaft. Check in Idle-up flight-mode.

#2 From the top position lower the collective down through the full range and then up through the full range. while doing so observe the contact between the three tool arms-to-swash arms, they ought to remain in contact throughout. Do like-wise in Normal flight-mode this time observe arm contacts as you go through the mid-stick position.

After refitting the rotor head, recheck for interaction in Normal flight mode.
First with the paddle at 90 degrees to port (pitch axis) with no cyclic input, as the collective progresses through the mid stick range there should be no deflection of the paddles. Do like-wise with the paddle direct ahead (roll axis).

If you reduce the Aileron and Elevator swash mixing percentages to say 45%, that will soften cyclic response.

Set both pitch curves to linier progression
Idel-up 00; 25; 50; 75; 100
Normal 50; 62; 75; 87; 100

If all is right the heli ought to lift-off by half-stick in Normal flight-mode.

I've fitted fast acting digital servos on all my 450 clones, much better resolution than analog servos.

Burgess

tomstr65 · Posted: Sat Oct 04, 2014 7:01 am Post subject:

tomstr65 · Posted: Sat Oct 04, 2014 7:05 am Post subject:

The problem is before i. Try. To lift off tail spins and i cant trim it to stop

Burgess · Extreme 3D Joined: 27 Mar 2012 Posts: 1101 Location: Wales

Thanks for the photos,

Looks like a problem with the gyro seems to be on its side.
Need to check how it's working.

Remove two of the motor wires spread-out the main blades,
turn on the transmitter, then energise the receiver.

Check the function of the tail rotor:

Switch into rates (idle-up) flight mode.

Observe the tail rotor pitch slider,
#1 Hold the vertical tail fin and move it left and right.
Does the tail rotor slider move on the tail drive shaft?

#2 Now hold the vertical tail fin and move it up and down.
Does the tail rotor slider move on the tail drive shaft?

If the tail slider responds to the up and down movement, the remove the gyro give it a quarter turn and refit with new double sided tape. So that the flat square side is down onto top of boom holder.

Test tail movement again side to side.
Set the tail rotor with a blade upwards
Move the tail side-wise left or right and the leading edge of the blade should point in the opposite direction to that movement.
Note: when the blade is up, the leading edge faces back-wards.

Next, test response to transmitter rudder control input.
Move the stick to the left and the leading edge of the blade should point to the right.

Burgess

tombo242 · Posted: Sat Oct 04, 2014 7:00 pm Post subject:

Great spotting and suggestions there Burgess, should solve the gyro problem.

Wonder why it was put on its side? Confused

Tom.

tomstr65 · Posted: Sat Oct 04, 2014 8:37 pm Post subject:

tomstr65 · Posted: Sat Oct 04, 2014 8:41 pm Post subject:

IM SO A.D.D. FORGOT TO ASK WHAT DOES MY FLIGHT MODE SWITCH DO??? Should i mount my gyro on its back? Im not sure i should try to fly!!like i can??yea right....anyway im having a low speed vibration..its a bent spindle!! I bought this heli used..anyway just needed to know about the flight mode switch and what it does?? And re mounting the gyro?

Burgess · Extreme 3D Joined: 27 Mar 2012 Posts: 1101 Location: Wales

tomstr65 if you fill in your location one of us in your area/country will be able to tell you the best local vendor for replacement parts...you'll be needing them some-when. A set of training gear will pay for itself.

Yeah don't try flying your heli just yet...
Fit a new tail rotor shaft, Align best quality not too expensive.
Best check the main and feathering shafts also the flybar too.

Yes re-fit the gyro on its back, wires aline fore and aft, and use new double sided tape, the gyro must be secure.

FLIGHT MODE SWITCH selects Normal and Stunt flight modes.
Stunt provides full negative through to full positive pitch deflections.
Normal provides the positive half of that range.

However, first you'll need to know what all the controls on the transmitter doo, and how to change settings so you'll need one of these:
http://www.horizonhobby.co.uk/aeroonline/e6spektrum/e6dx6i/SPM6600_Manual_DX6i.pdf
http://spektrumrc.com/ProdInfo/Files/SPM6600_DX6i_Manual-LoRes.pdf

and watch these
DX6i & CCPM Full Setup Guide Part 1 Setting Up The DX6i
http://www.youtube.com/watch?v=uxWhzYzMEPY

http://www.youtube.com/watch?v=o8gU_x3vBBw

Burrgess

tomstr65 · Posted: Sat Oct 04, 2014 11:55 pm Post subject:

Thank you...i changed my location! Spring texas!! YAAA HOO!!! No i dont own a horse!!! Anyway i will not fly you are correct!! Im going to test the rotor again after belt replacement..buy a mailshaft...and re mount the gyro...thanks i will test fly after fethering shaft replacement! Should my rutter switch be on ZERO OR 1 ??

tomstr65 · Posted: Sat Oct 04, 2014 11:57 pm Post subject:

Burgess · Extreme 3D Joined: 27 Mar 2012 Posts: 1101 Location: Wales

RUDDER D/R (Dual Rate) switch, I would set to ‘0', however, by reason of being second-hand, best to check-out all the settings in the transmitter before you fly.

See if the settings in the transmitter are ACT (active) or INH (inhibited) and check the setting in both ‘0' and ‘1' for all three dual rate switches. (See page 62 & 63 Dual Rate and Exponential in the manual).

Burgess