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HomeAircraftHelicopterBeginners Corner › Set up problem with T-Rex 450 and DX7 Radio
06-05-2009 10:48 AM  9 years agoPost 1
OneHoof

rrApprentice

Cold Spring, Kentucky

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Hey Man,

I have a T-Rex 450 and it sounded different from my other two T-Rex's I've owned when I spooled them up. It sounded like the rpm's were too high... My other Rex's would lift off just a little past mid stick, but this one was much higher.

For safety's sake, I took it outside on a calm day and it flew fine after it finally took off. However, later when I tried modifying the name, it seemed that I deleted all programing in the radio. So, now the swash plates aren't even when you do up and down collective. I made sure they were all 90 out at mid stick... and changed the lengths of a couple and the swash is perfectly level at mid stick.

But any movement up and down is not even!!! I reveresed the two side servos... and now the swash goes up and down perfectly level with collective inputs, but now the right and left cyclic are reversed (ie. push left, get right tilt... push right, get left tilt). I've been flying rc helis for a while, but I've never built one from scratch. I have rebuilt crashed ones... so I am confident that I can build one now.

However, I have never set up an rc heli... and this little T-Rex is kicking my butt. It is getting very frustrating. Do you have any tips or any web sites that might talk me through setting up the DX-7 radio and the T-Rex? In the past, any time I've rushed or tried to force a heli into flying, I always had a crash... So, I am taking my time with this situation.

I have tried everything I know to do from my limited set up experience... I am in Guantanamo Bay, Cuba and haven't met any other rc heli flyers here yet. Unless, I set up a helicopter club, I doubt there will ever be one here. My usual bird is a Raptor 30, but I am still trying to figure out how to get nitro methane shipped here.

Any tips or set up advice you can give me will be much appreciated. Especially considering it takes two weeks to get parts shipped here. Thanks!

Lone Wolf...in Cuba

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06-05-2009 01:18 PM  9 years agoPost 2
Skarn

rrVeteran

Pasadena, MD

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Go to helifreak and watch the Finless Bob setup vids for the 450. In particular watch his CCPM1 and CCPM2 vids..it will solve your issue.

But for a quick fix, if the swash is moving up and down with collective correctly, but the ail/ele is wrong...go to your swash menu and reverse that setting. For example if the ail are backwards, and the swash mix percentage is +60, make it -60.

Good luck,
Skarn

It's better to burn out than to fade away...

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06-05-2009 01:21 PM  9 years agoPost 3
RCHSF

rrKey Veteran

NC

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Hold the Down, and Select button down, and power the tx up, now press up, or down, and cycle thru the settings till you get to swash type, set it to 3 servos 120 degree.

Next Hold the down, and select buttons down, and this will save, and exit, now press them again. and then press up, or down, and cycle thru and look for Swash mix, set it to
Ail -60
Ele +60
Pit +60

This is if you have the Pitch servo on the right front side of the heli.

Ail servo left front, and of course the elevator in the rear.

Servo reversing

Throttle Normal
Ailron Reversed
Elevator Reversed
Rudder Reversed
Gear Normal
Pitch Normal

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06-05-2009 07:17 PM  9 years agoPost 4
OneHoof

rrApprentice

Cold Spring, Kentucky

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Hey guys,

That WORKED!!! You all are awesome!!! Now the collective is working correctly and so is the cyclic. The only problem is... I made a bunch of big adjustments on the pitch change links, yesterday, prior to getting the good info from you... So, now mechanically things are messed up (ie. pitch links wrong lengths)

I knew at mid stick the servos should all be at 90 degrees... and the swash plates should be perfectly flat. I measured 0 degrees pitch on both blades (if I am reading the pitch gauge correctly). Also, I was aiming for about 9 degrees positive pitch at full stick... and about 9 degrees negative at the bottom end.

When I took her outside for the initial run up... and possible test flight (that didn't happen). The rpm's were screaming and she was still on the ground. IN the past I would have kept increasing pitch like a dummy... and probably would have shot up in the air and I would have crashed. But my experience (for the first time) stopped me from adding anymore collective... because I was already at 3/4's stick and that thing was screaming!!!

Also, when I first plug it in, instead of going through its series of test beeps, it has a continous beep...beep...beep...beep...beep...beep! After trying a few things that didn't work. I flipped it up into stunt mode two (idle up) and the beeping stopped and it went into its series of test beeps and I was actually able to start it up.

Btw, the kill switch on the right has no affect... to kill the power, in normal mode yesterday (of course, today normal mode doesn't work). So, obviously I've screwed some stuff up in the radio programing and messed some things up with the heli's pitch change settings.

I'll try to find Finless Bob's set up videos... I knew enough to have it in CCPM 120 degrees... but still have a lot of corrections and fine tuning... before I can get this bird safely flying. I just need to overcome my old ways of inpatience that has caused so many avoidable crashes. Thanks for the info... Is there anything else that you might suggest to fix this... on my own? Thanks again!

Lone Wolf... in Cuba

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06-06-2009 12:05 AM  9 years agoPost 5
LONEWOLF2440

rrElite Veteran

MYRTLE BEACH S.C

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hello brother

MIKADO LOGO 600 TREX 550

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06-07-2009 01:44 AM  9 years agoPost 6
OneHoof

rrApprentice

Cold Spring, Kentucky

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Howdy!!! How's the weather in South Carolina?

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06-07-2009 03:02 AM  9 years agoPost 7
lstmysock11

rrNovice

Middletown, CT

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Not sure if it is the same thing, but on my 450 when I had a problem with the new ESC it turned out that I needed to go into servo reversing and reverse the throttle. Then I powered the bird up and then it started normaly and would spool up.

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06-08-2009 02:18 AM  9 years agoPost 8
OneHoof

rrApprentice

Cold Spring, Kentucky

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Making progress..
Hey Guys,

I have the swash fixed by putting -60 Ail... However, the mechanical changes I made to the lengths of the pitch change links have it screwed up mechanicallly now.

Also, during a run up today I made an amazing discovery!!! The tail rotor was spinning the wrong way!!! So, that explains the strange sound it was making. The crazy thing is the thing flew with no problem when I first got it.

Granted, it sounded funny... So, now I took the tail boom off and flipped the belt around so that the tail rotor is spinning (counter clockwise) the way it should be.

Of course, the blue metal servo holder/attachment broke and I don't have a replacement. The original one was broke when it shipped here and I replaced it.

Now it still gets a lot of rpm's and doesn't take off. I am hoping that if I can get something to measure the pitch change links and get them to the proper length that everything will be fixed.

I can't find fault with the guy who built it... At least he had the guts to try. I've never built an rc heli out of the box. I've rebuilt several after crashes... and probably could. But this is the first heli I've tried to set up.

I'm almost starting to think it would have been easier to have built a kit from scratch... I don't think this guy used loc-tight. The engine runs very strong and it's a good looking bird. It's just a question of how long it will take me to get it set up right and flying!

I've found some helpful videos on You Tube, but haven't been able to open any of Finless Bob's... Any tips for getting the pitch change links right? Hopefully, once I do that, get everything 90'd, and the swash plates level... I'll have a nice flying bird. Wish me luck! Thanks!

Lone Wolf in Cuba

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06-08-2009 02:27 AM  9 years agoPost 9
lstmysock11

rrNovice

Middletown, CT

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As far as the tail going the wrong direction, you need to fix the belt going to the tail so the tail rotor will run counter clockwise. main rotors run clockwise and tail goes counter clockwise.

If it wont lift off you need to check your pitch at midstick to make sure it is at zero pitch and get about 10 to 11 at high stick and -10 or 11 at low stick. Do you mean the servo mount for the tail servo? I know the plastic ones normaly come with the align tailbooms.

Not only do you want the swash level but you also want enough room at bottom stick and high stick that none of the servo links will bind and the swash plate will not hit the frame of the bird.

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06-08-2009 02:52 AM  9 years agoPost 10
OneHoof

rrApprentice

Cold Spring, Kentucky

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Making progress...
Yes... I am only shocked that I didn't notice the tail rotor was spinning the wrong way sooner. I removed the tail boom and pulled the belt out completely to ensure it wasn't twisted.

Now I have it in correctly and the tail rotor is spinning counter clockwise, with advancing blade spinning upward into the downwash of the main rotor, to get more bite, as they were designed to do.

I am very surprised it flew okay spinning the wrong way. I'll keep an eye on that with the swash plate. At least, I have learned to have patience. When I first got into the hobby, my haste to get it flying would have caused me to crash it by now.

Some of the ball links are chewed up anyway. I should probably replace them to be on the safe side. Thanks for the tips. I can use all the help I can get. If I were in the states, I'd be getting with an experienced builder and getting some help. But now that I'm stuck on this island... I am on my own. RC helicopter survivor!

Lone Wolf in Cuba...

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06-08-2009 01:20 PM  9 years agoPost 11
Skarn

rrVeteran

Pasadena, MD

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Believe it or not, the direction of the tail rotor makes little difference on these small helis! That is as long as the blades are facing the proper direction (leading edge in direction of travel).

You'll hear a lot of people swear the tail will spin like crazy if they go the "wrong" way...but it's simply not true. My bro in law had his going the "wrong" way for over a year...I believe he still does and it flies beautifully! Think about it....how could people fly inverted

Skarn

It's better to burn out than to fade away...

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06-11-2009 12:47 AM  9 years agoPost 12
OneHoof

rrApprentice

Cold Spring, Kentucky

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Gyro/Tail rotor problems...
Hey Guys,

Now I seem to have the other bugs/problems worked out (ie. tail rotor spinning correct way, swash problems corrected etc.) But now anytime it gets light on the skids it spins like crazy.

I have the rudder reversed in the radio because otherwise, the nose goes right when left input is put in and vice versa. I'm guessing something might be wrong in the radio set up.

I have a SPEKTRUM DX7 radio and currently these are my settings:

(GYRO SENS)
>AUTO F. MODE
NORM:0
RATE: STNT:0
0: 50%
1: 50%
_____________________________________

(REVO MIX)

NORM STNT
>UP 0% UP 0%
DN 0% DN 0%
_________________________________________

(AUTO D/R EXP)

>NORM INH
ST-1 INH
ST-2 INH
HOLD P-1
_______________________________________________

FUTABA GY401 SETTINGS:

DS= ON
DIR= NOR.
DELAY= 65 OR 0
LIMIT= 120 OR 60
________________________________________________

Please remember, this is my first set up by myself... So, there is probably something blatantly WRONG that would be obvious to you guys, but I am oblivious to... So, any tips... or corrections would be much appreciated. It's been 3 months since I've flown a helicopter, so I'm chomping at the bits to get an rc one up and flying, til I can get back to flying full scale. Thanks for all of your help, adivice and wisdom. ttys

Sincerely,

Lone Wolf in Cuba

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06-11-2009 01:01 PM  9 years agoPost 13
Skarn

rrVeteran

Pasadena, MD

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(GYRO SENS)
>AUTO F. MODE
NORM:0
RATE: STNT:0
0: 50%
1: 50%
Using the Gyro Sense menu, at 50% gain, you are just barely in hh mode. You need to up your gain...put it at 72% as a starting point and see how it works for you.

If your heli still spins on spoolup, flip the reverse switch on the gyro.

Good luck,
Skarn

It's better to burn out than to fade away...

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06-11-2009 04:02 PM  9 years agoPost 14
OneHoof

rrApprentice

Cold Spring, Kentucky

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Anti torque problem seems to be fixed...
Hey Skarn,

It took about 45 minutes of making adjustments to the radio gyro sensitivity... to 72%... and it still spun. I notieced it was already in Reverse mode on the gyro, so I set it back to normal. Every time it wanted to spin... I flipped DS to OFF... still spun... back to DS ON.

Btw, I should have asked... the builder mounted the gyro on the left side instead of the right side like all the other T-Rex's on here. Does that matter? I mean putting it into reverse should fix that right?

Anyhow, after a few dozen experiments with the manual gyro settings (ie. Delay and Limit)... and flipping the gyro manually back to reverse again. I finally hit the sweet spot and the nose is holding. On the tile floor here at work.

I noticed it was sliding left and backward so I added a lot of trim. I then took it outside to the concrete pad and managed to bring it up to a low hover with no problems. Any time there was a slight breeze it got into translational lift and wanted to climb, then I'd chop the throttle... and the breeze would die out, then it'd suddenly start dropping... then I'd add just enough collective (sometimes) to keep from slamming into the concrete.

I almost lost control during one of those bobbing up and down sessions and noticed an occasional tail wag. A few were caused by it bouncing off the ground as I tried to keep it from bobbing. Manually I have Delay set at about 50 and Limit set at about 120. Of course, I do not know what Delat and Limit do... I'd guess they set sensitivity and reaction time... to avoid tail wag?

Now I need to fine tune the rotor blades and make sure they are tracking properly. When there was no wind, it hovered very well. Of course, I had to take the excess trim out because as she got light on the skids it leaned hard right and forward.

Currently, I manually have 4 klicks forward on cyclic trim... and 3 clicks to the right/cyclic. I have the collective/throttle dead center with the trim (maybe that's why it was bobbing so much? Maybe my rpm's are too low?).

A few days ago, the metal bracket that holds the gyro servo in place cracked/broke as I made adjustments to the pitch change links to level the swash plates. The original bracket was broke when I bought it... and there was an extra one as this heli had a ton of spare parts. Of course, I took the lazy route and spread it open instead of going through the headache of removing the tail boom.

Well, my guess is the stress of flexing it open and closed is probably what caused the new one to break. I currenty have it Jerry Rigged with a velcro battery fastener. I know this isn't good... but I wanted to get this heli tracking stable and flyable. I will order a few extras from heli proz when I get paid.

I am just glad I regained control when it shot up in the air and I started losing it. It was a very close call. I wasn't able to hold it in at a stable altitude (out of ground effect) long enough to see if the blade tracking was good.

It sounds much better since I flipped the belt and the tail rotor is spinning in the right direction. During the dozens of spool ups I did... I made sure my pointer finger was covering the throttle hold switch to kill power as soon as it started to spin.

I have my Raptor 30 here... but need to contact a private individual to get nitro methane shipped down here. The post office told me that they are authorized to ship remote model glow power fuel with ground shipment. Despite the fact (I recently learned) all of our mail comes on an airplane (not a container ship), they said they will still ship it... because it is still considered a ground shipment. UPS and FEDEX cannot deliver to an APO... and most rc companies use either UPS or FEDEX.

Well, at least I have my Raptor almost tuned up for flight. Thank you for all of your help. It get's VERY frustrating... VERY fast when you keep running into dead ends. I almost think I could actually do a complete build and set up of a bird now.Maybe when I get back to the states? THANK YOU!!!

Lone Wolf in Cuba

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06-12-2009 11:11 PM  9 years agoPost 15
OneHoof

rrApprentice

Cold Spring, Kentucky

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Almost set up...
Hey Guys,

Thanks for the great tips. I almost have it set up! It is no longer spinning on me. but now I'm getting a tail wag. I'll just have to keep turning the gyro down til it stops.

I noticed I only have +5 degrees and -5 degrees pitch in the blades. I am okay with keeping the -5 degrees for now... but I need more positive pitch. The manual says +9 pitch...

How do you increase the pitch? I notied on my test flight last night, when it was completely calm (NO wind at all). That the helicopter was bobbing (rising and falling) like when you are flying in the wind and it reaches translational lift!

I was not adjusting the collective at all and it just kept rising and falling... sometimes hitting the ground... when I raised the collective at the last second.

I increased the collective/throttle trim to max... to get more rpm's, but that did not fix the bobbing problem.

I finally got the blades tracking very nicely. If I could get the gyro tuned in right (no tail wagging)... and get the pitch right... and get it to stop bobbing up and down I think my helicopter will FINALLY be ready. Thanks in advance for any tips/help you can offer. I'll talk to you soon.

Lone Wolf in Cuba

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06-22-2009 02:53 AM  9 years agoPost 16
OneHoof

rrApprentice

Cold Spring, Kentucky

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Won't hold altitude...
All of the other problems are fixed. However, the T-Rex will NOT hold altitude. I have flown it a few times in completely calm wind conditions and it rises... and then falls... just like when flying in windy conditions. But there is not any wind to cause these variations in altitude.

I have about 10 degrees positive pitch and -5 degrees pitch. The blades are tracking perfectly... So, I am mystified as to why it would bounce from a 3 foot hover to ten feet... then drop... almost to the ground, with no collective inputs.

The only theory I can come up with is maybe the batteries are not good? Or maybe the wiring connectors aren't good... causing a weak... or imperfect electrical current to the motor. Hence, with disruptions... variations, maybe the engine/rotor rpms are fluctuating enough to cause these crazy, uncommanded, altitude changes.

Other than that... maybe my pitch curves aren't set right? I am not sure... Has anyone seen or experienced this problem before with a T-Rex 450? Any suggestions of how to fix it? Thanks.

Lone Wolf in Cuba

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