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T-REX 250 › T-Rex 250 / DX7 Setup
12-26-2008 05:48 PM  8 years agoPost 1
gmcullan

rrKey Veteran

Southbridge, MA

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Responding to some PM,s, please note below the settings I use with my Spektrum DX7 and T-rex 250.

Please note, these settings are neither right nor wrong. They are simply what works well for me in regard to how my 'Rex 250 is adjusted and flown. Your results may vary

Best regards,

Gerry Cullan

Gerry Cullan,
Gaui 200, 255; T-Rex 250, 450 SE & SA, Mini-Titan, Blade 450

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12-28-2008 04:40 PM  8 years agoPost 2
gmcullan

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Southbridge, MA

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Hmmm, a bunch of "reads" but no comments. While I might not have expected agreement, I did expect a couple of "are you nuts?" comments.

A word or two about how my 250 is adjusted. With the mixing arms level, all links are adjusted so that at center stick the servo arms are at 90 degrees and the main blades are at 0 pitch. Because of making one-turn adjustments on the ball links, i.e., always keeping the outside of the link facing as it should, there are some small variations in settings.

Anyone else want to post their DX7 settings? It might be interesting to compare what differences we might have.

Gerry Cullan,
Gaui 200, 255; T-Rex 250, 450 SE & SA, Mini-Titan, Blade 450

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03-14-2009 07:08 AM  8 years agoPost 3
slappy901

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Houston, TX USA

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Hmmm, a bunch of "reads" but no comments. While I might not have expected agreement, I did expect a couple of "are you nuts?" comments.

LOL!

No not nutz, I did very little tweaking on what you have here. I took the paddles off of mine and replaced them with some from a crappy walkera I had in the closet that were much lighter and could still handle it even though I am a newb, Your fine man. Excellent post!

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03-14-2009 01:01 PM  8 years agoPost 4
ShineyObject

rrNovice

Dalton, Georgia -​USA

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Thanks! I'm supposed to help a friend this weekend with his 250 and DX7 so this will help me a lot since I use the 10C.
First glance looks good...

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03-14-2009 02:35 PM  8 years agoPost 5
inkspot1967

rrProfessor

Cranston Ri

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well i have mine setup nothing like that at all, you have alot of subtrim in there and i have 0 subtrim your thr curves are all funky i use strait 0 50 100 in all

rudder 25%?????? it must be very slow

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03-14-2009 03:11 PM  8 years agoPost 6
dizzymarkus

rrVeteran

Oswego, NY

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The tuff part is you listed no electics -- servos are different, gyro, servo rev etc -- Exact equipment should be spot on :0) missing a turn or two

Markus

I reject your reality and substitute my own :0)

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03-14-2009 03:56 PM  8 years agoPost 7
Kyalamikid

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South Africa

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Why dont you just shorten your swash links? 63% for 0 degrees is...wierd?

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03-14-2009 04:02 PM  8 years agoPost 8
inkspot1967

rrProfessor

Cranston Ri

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yeah somethings not right on it your pitch curves should be 0 50 100.

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03-14-2009 04:07 PM  8 years agoPost 9
Quandumphone

rrApprentice

Yuma, AZ

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His pitch curves are fine if 50 is not 0 degrees, which appears to be the case. It's easier to comprehend 0 - 50 - 100 but they are just numbers. The output on the blades is what's important and he has that listed correctly on the side.

Before you think I'm crazy... Personally, I'd adjust the links so the curve would be correct at 0 - 50 - 100. The math is easier. I would also change the midpoint on the normal curve to match my idle ups. This prevents jumping up or down when switching.

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03-14-2009 04:13 PM  8 years agoPost 10
TMoore

rrMaster

Cookeville, TN

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29 points of subtrim in rudder doesn't look right to me. There is a lot of subtrim on everything and it's pushing the limits even for a 250 size machine. I know the Align servo arms are a PIA to get on with but it is still a lot of subtrim.

TM

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03-15-2009 05:38 AM  8 years agoPost 11
gmcullan

rrKey Veteran

Southbridge, MA

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I now have two of the Super Combos. The second one required much less subtrim to center the servos from the "best" possible servo arm installation. All links are spot on for Align's lengths listed in the instructions. Those lengths result in some of the funky numbers. The numbers are not the important thing, the resulting pitch settings are. With the swash at mid-travel, washout and mixer arms are as close to right angles to the main shaft as you can get without lazer alignment. Idle "0" is set with a little positive pitch at mid-stick because, well, that's the way I like it. Like I said, it works for me. Your results may vary.

Also, I moved the ball link in on the rudder servo arm and increased the throw in the programing settings. I don't remember the numbers, as I just got back from a slot car race and it's quite late. But both 250's are set up this way. Regardless, the tail is plenty fast for the way that I fly

Gerry Cullan,
Gaui 200, 255; T-Rex 250, 450 SE & SA, Mini-Titan, Blade 450

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03-15-2009 06:02 AM  8 years agoPost 12
TMoore

rrMaster

Cookeville, TN

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29 points of subtrim on the tailrotor means that the gyro is always getting a command to rotate.

TM

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03-15-2009 07:07 AM  8 years agoPost 13
Kyalamikid

rrNovice

South Africa

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Why dont you use a circular servo arm and drill the hole yourself, or rotate a 4 arm until you get one thats at 90 degrees?

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03-15-2009 03:55 PM  8 years agoPost 14
gmcullan

rrKey Veteran

Southbridge, MA

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Professor Moore, I am interested in your comment about the command to rotate. Once the settings are entered and binding is completed to the receiver, doesn't the system now accept the subtrim position as the "zero" point? I have no issues with the gyro presenting unwanted yaw commands. Additionally, my tail rotor linkage has been adjusted so that tail rotor trim is "zero". I've tried adjusting my swash such that pitch and roll trim zero. But keeping with the convention that the "A" on the link faces "out", a spot on adjustment was not possible. So both my 250's have a couple of clicks of pitch and roll trim.

Having had Blade CP and HoneyBee CP2 helis as well as an HDX300 (an evil machine!), the T-Rex 250 just blows by those machines in stability and overall "flyability".

And as I've said all along, these are how my machines are set up. It works for me. Your results might be different.

Gerry Cullan,
Gaui 200, 255; T-Rex 250, 450 SE & SA, Mini-Titan, Blade 450

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03-15-2009 04:16 PM  8 years agoPost 15
TMoore

rrMaster

Cookeville, TN

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Professor Moore, I am interested in your comment about the command to rotate. Once the settings are entered and binding is completed to the receiver, doesn't the system now accept the subtrim position as the "zero" point? I have no issues with the gyro presenting unwanted yaw commands. Additionally, my tail rotor linkage has been adjusted so that tail rotor trim is "zero". I've tried adjusting my swash such that pitch and roll trim zero. But keeping with the convention that the "A" on the link faces "out", a spot on adjustment was not possible. So both my 250's have a couple of clicks of pitch and roll trim.

Having had Blade CP and HoneyBee CP2 helis as well as an HDX300 (an evil machine!), the T-Rex 250 just blows by those machines in stability and overall "flyability".

And as I've said all along, these are how my machines are set up. It works for me. Your results might be different
Please dispense with the professor BS, I'm not a degreed professor in any discipline, I'm a pilot just like everyone else.

In the picture you posted, there is a value of R29 in the subtrim column. If as you say, your linkage has been adjusted so that tail trim is "zero" why is there 29 points of subtrim on the rudder channel? If you rebind the TX to the RX, the new position is accepted as neutral but why use subtrim on the rudder channel to start with?

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03-15-2009 04:24 PM  8 years agoPost 16
inkspot1967

rrProfessor

Cranston Ri

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^^ i agree completely with TMoore

there is no need of using any subtrim on anything just find the right servo arms and get it spot on its not that difficult. adding subtrim leads to interaction and on the tail not being neutral.

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03-15-2009 04:29 PM  8 years agoPost 17
caseyjholmes

rrElite Veteran

Portland, Oregon

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Shoot for 15 points or less of subtrim on each servo if properly set up.. No rudder subtrim. Sometimes you will get lucky and require no subtrim on a servo with the correct horns but most of the time they will still need a couple clicks even with the right horns and degree.

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03-15-2009 04:37 PM  8 years agoPost 18
ajnstajn

rrApprentice

Slovenia, EU

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So what is then better. To have a few clicks of subtrim and servo horn exactly 90 to the servo case or to use no subrtim and try to find the best servo horn even tere is none that is 100% perpendicular?

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03-15-2009 04:39 PM  8 years agoPost 19
caseyjholmes

rrElite Veteran

Portland, Oregon

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Get the servo horn as best you can. If it won't line up flip it around and try the other arms on the horn. The splines are offset in degrees. Just turn the horn until it lines up as best you can. You will still probably need a click or two of subrim, unless you are speaking of the rudder servo. In which case, no subtrim, line the horn up as close as possible and leave it, even if it's not at 90*. (but it should be very close.. like to within 1 degree or so).

What I mean is, if you have to go over say about 15 clicks of subtrim, you could probably find a horn position to line up closer/better to use less subtrim.

When adjusting rudder servo in rate mode(yaw trimming), do not use subtrim. Move the tail servo mount forward or backward, or adjust your linkage rod longer or shorter.

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03-15-2009 04:50 PM  8 years agoPost 20
inkspot1967

rrProfessor

Cranston Ri

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also make sure all radio trims are center before setting up the servos.

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T-REX 250 › T-Rex 250 / DX7 Setup
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