Discussion Trex-500 HANGAR

[hancockdw]

Originally Posted by Evan D

I was Dave, if you are charging a 6S 3000mA at 2C convert it all to watts which is 133 (rounded). Since your power supply only supplies a certain voltage (mine is around 14) divide the watts by your power suplly voltage and that's what it has to put out with a little extra for losses. My math shows 9.5 amps. That may be what you did but without the watts explanation??

Watts is a way to express power which is volts times amps (V x A=W).

I bet the difference in our figures is the difference in our P/S's output voltage. Mine's 12V almost exactly.

6 (cells) x 4.2 (V) x 6 (A, for 2C) = 151.2

Oh! You're using nominal voltage for the cells, aren't you? If I use 3.7 for the cell voltage I get 133. Pretty sure you need to use the voltage goal there.

Using 151W, if we divide by 14V it's 10.78A, with a 12V supply it's 12.58A.

Dave

[Evan D]

Justin, there is more than one way to set up a helo and most work in the end. The benefit of setting it up a certain way is if you need help that person will be able to easier see what need to be altered.

My way is to set up the helo in idle up 2 mode with the cyclic servos at mid stick and all trims and sub trims off. With it like this I put the servo arms on as close as I can get them to have a 90deg angle to the linkage rods. (on some helos this is level). Fine tune with the sub trims. Then I adjust all the links to get the radius arms, mixing arms and blades level at 0 deg.

Once there I put the ID2 curve at 0-25-50-75-100, servo travels all at 100, and swash mixes at 60-60-60 and see what I have for full positive and negative pitch. I also give full aileron and elevator throws to see how much that has. If everything is close I adjust with programing from there but sometimes it's way off and you may have to move the balls on your servo arms to get it close. The Align manual is usually pretty good up to this point.

Then I use the swash mix programing for pitch to get the recommended full travel. (12 for the ESP). On my ESP this came out to 53 on my DX7.

Then I use the swash mix to get the most aileron and elevator cyclic. 70 on both came close to binding for me.

Then the last thing is to do the Finless technique of getting rid of CCPM interactions using servo travels to keep the bubble centered n a level on the paddles. To be honest i don't know how much this step really give most people but I take the time to do it since I like to fiddle with things. This step usually takes a lot of time and seems to never be perfect.

After all this is done I recheck for travels and binding and then, and only then I set up my normal and ID1 curves.


All that said, that is my way to do it and like I said there are others. One way is to set the 60-60-60 and then use servo throws to get all your pitches right. But to me you end up with a big mess in the servo throw menu.

[hancockdw]

jmpwnd:

I always weigh blades. I have a little cheapie scale, but it seems to be pretty accurate, and it's supposed resolution is .1g. My main blades were balanced, tail blades required one piece of tape.

After thinking about it, I think I recall that there is some vibration discernible at the tail during spinup. Nothing noticeable at the head.

Proper blade tension is still a black art to me. I usually just try to get 'em tight enough so you can't twist 'em in the grips and they don't "gravity flop".


I have a new problem. I was about to put on the blade holder/caddy and hang the bird on the wall when I noticed a tick somewhere in the tail. I turned the head by hand and note that the tick happens several times during one revolution of the tailbox gear. Hard to locate the sound but doesn't seem to come from either end. The only thing in the middle that could make a noise is the bearing. I wouldn't have guessed I'd be buying replacement parts quite so soon!

Dave

[Evan D]

Originally Posted by hancockdw

I bet the difference in our figures is the difference in our P/S's output voltage. Mine's 12V almost exactly.

6 (cells) x 4.2 (V) x 6 (A, for 2C) = 151.2

Oh! You're using nominal voltage for the cells, aren't you? If I use 3.7 for the cell voltage I get 133. Pretty sure you need to use the voltage goal there.

Using 151W, if we divide by 14V it's 10.78A, with a 12V supply it's 12.58A.

Dave

Sounds like we are doing the same thing Dave.

[jmpwnd]

Originally Posted by hancockdw

jmpwnd:

I always weigh blades. I have a little cheapie scale, but it seems to be pretty accurate, and it's supposed resolution is .1g. My main blades were balanced, tail blades required one piece of tape.

After thinking about it, I think I recall that there is some vibration discernible at the tail during spinup. Nothing noticeable at the head.

Proper blade tension is still a black art to me. I usually just try to get 'em tight enough so you can't twist 'em in the grips and they don't "gravity flop".


I have a new problem. I was about to put on the blade holder/caddy and hang the bird on the wall when I noticed a tick somewhere in the tail. I turned the head by hand and note that the tick happens several times during one revolution of the tailbox gear. Hard to locate the sound but doesn't seem to come from either end. The only thing in the middle that could make a noise is the bearing. I wouldn't have guessed I'd be buying replacement parts quite so soon!

Dave

Dave,

I think it was the blade balance...I just spent an hour balancing them and after only one spool-up, it was very much improved. Just a slight jiggle now, which could be a bit more imbalance, low-speed shakes, or the tail I guess. These Align 425D CF blades were horribly out of balance! I'm a bit surprised, to be honest...

On your tail clicking, does the TT feel notchy or chunky while spinning it? The bearing could be slipping on the TT if you didn't put enough CA on it. I messed with CA'ing the TT bearing several times before I figured out the best way to do things. It popped free a few times while just spinning it in my hand or forcing it along the TT just barely. If you didn't grease the boom and rubber bearing cover sufficiently, then you could have popped it loose or at least weakened the CA bond. Just a thought...

I feel like I'm a bit too new yet to give advice, but you guys have been so helpful to me, I figured I'd give it a try!

-->Justin

[RotorJockey]

Originally Posted by jmpwnd

Dave,

I think it was the blade balance...I just spent an hour balancing them and after only one spool-up, it was very much improved. Just a slight jiggle now, which could be a bit more imbalance, low-speed shakes, or the tail I guess. These Align 425D CF blades were horribly out of balance! I'm a bit surprised, to be honest...

On your tail clicking, does the TT feel notchy or chunky while spinning it? The bearing could be slipping on the TT if you didn't put enough CA on it. I messed with CA'ing the TT bearing several times before I figured out the best way to do things. It popped free a few times while just spinning it in my hand or forcing it along the TT just barely. If you didn't grease the boom and rubber bearing cover sufficiently, then you could have popped it loose or at least weakened the CA bond. Just a thought...

I feel like I'm a bit too new yet to give advice, but you guys have been so helpful to me, I figured I'd give it a try!

-->Justin

Justin, what blades are you running?

[RotorJockey]

Originally Posted by hancockdw

jmpwnd:

I always weigh blades. I have a little cheapie scale, but it seems to be pretty accurate, and it's supposed resolution is .1g. My main blades were balanced, tail blades required one piece of tape.

After thinking about it, I think I recall that there is some vibration discernible at the tail during spinup. Nothing noticeable at the head.

Proper blade tension is still a black art to me. I usually just try to get 'em tight enough so you can't twist 'em in the grips and they don't "gravity flop".


I have a new problem. I was about to put on the blade holder/caddy and hang the bird on the wall when I noticed a tick somewhere in the tail. I turned the head by hand and note that the tick happens several times during one revolution of the tailbox gear. Hard to locate the sound but doesn't seem to come from either end. The only thing in the middle that could make a noise is the bearing. I wouldn't have guessed I'd be buying replacement parts quite so soon!

Dave

Dave,

Do Not! just go by weight for balance! If you do, you will never have a balanced rotor system!

You also have to take into account where the weight is on the blade. That's what a blade balancer does.

Example: If 2 blades weigh exactly the same, but one blade has more weight inboard and the other outboard, the heli will beat itself to death! Centrifugal force is what you want to equalize and you do that with a blade balancer.

But that being said, I have NEVER bought a set of carbon fiber blades, either align or other that didn't come to me already balanced. And trust me, I've bought ALOT of blades!

Regarding blade tension, nothing black about it. Loose blades are better than tight blades. Centrifugal force will make them aligned and rigid. I set mine (both head and tail) to where they can be moved in the grips. but stay where I put them. If they are hard to move and the grips are cutting into them, they're too tight.

Regarding the tick:

Your heli is an ESP, right? Turn the main rotor, hear rhe tick. Pull 2 bolts, 1 ball link and remove the tail rotor. Turn the main rotor. Don't hear the tick, look for it in the tail rotor. Hear the tick, 2 tailboom bolts and loosen the stab, slide the tailboom back. Turm the main rotor. Don't hear the tick, look for it in the t/b or bearing. Hear the tick, it's in the main/tail drive gear train.

I wouldn't get too upset about it, just track it down and make it right.

Fred

[jmpwnd]

Originally Posted by RotorJockey

Dave,
But that being said, I have NEVER bought a set of carbon fiber blades, either align or other that didn't come to me already balanced. And trust me, I've bought ALOT of blades!
Fred

Fred,

Really?! So I must have gotten a bad set of blades here...hmmm. If I'm going to pick up a new set of blades, what would you recommend?

The balancing job I did was rough...I had to wrap the blade in tape a couple times around. It's not ideal and I made it as pretty as it could be, but it should work for a bit of hovering until I find another set of blades. I know I'm new all over again, but I'll tell you that in all my experience of balancing props and blades in the 90's, I don't seem to recall anything as unbalanced as these blades.

Cheers,
-->Justin

[hancockdw]

RotorJockey:
I also check CoG by rolling the blades over a main shaft. Both of mine "fall over" very close to the same time. Now that you mention it, though, the piece of tape I put on the tail blades is toward the end of the blade. Probably should have put it in the middle!

Roger your procedure for tracking down the "tick". Just haven't got started on it yet. And I'm going to buy some spare parts for it in any case.

jmpwnd: Thanks for your advice. Noob or not, sounded pretty good to me!

Dave

[hancockdw]

Originally Posted by RotorJockey

Regarding blade tension, nothing black about it. Loose blades are better than tight blades. Centrifugal force will make them aligned and rigid. I set mine (both head and tail) to where they can be moved in the grips. but stay where I put them. If they are hard to move and the grips are cutting into them, they're too tight.

Forgot to comment on this. When I said I run the blades tight enough that they won't twist, I meant in the plane of pitch rotation of the blade grips. They are snug but movable, like what you said. When I first put 'em on I didn't realize the blade grip nuts hadn't seated in the recesses -- the blades wound up being positively floppy!

[DoctorAudio]

Originally Posted by jmpwnd

Fred,

Really?! So I must have gotten a bad set of blades here...hmmm. If I'm going to pick up a new set of blades, what would you recommend?

The balancing job I did was rough...I had to wrap the blade in tape a couple times around. It's not ideal and I made it as pretty as it could be, but it should work for a bit of hovering until I find another set of blades. I know I'm new all over again, but I'll tell you that in all my experience of balancing props and blades in the 90's, I don't seem to recall anything as unbalanced as these blades.

Cheers,
-->Justin

Originally Posted by hancockdw

RotorJockey:
I also check CoG by rolling the blades over a main shaft. Both of mine "fall over" very close to the same time. Now that you mention it, though, the piece of tape I put on the tail blades is toward the end of the blade. Probably should have put it in the middle!

Roger your procedure for tracking down the "tick". Just haven't got started on it yet. And I'm going to buy some spare parts for it in any case.

jmpwnd: Thanks for your advice. Noob or not, sounded pretty good to me!

Dave

Guys not even time I have had to balance a set of blades, but it is just good practice to check them anyway!
I check every set that goes on my birds. I find myself not checking them enough on my planes. Maybe it is because I don't care enough for the planes I have. But the larger one , like the 27% yak I have I check them all the time!

[henryd123]

hi there guys,I have just hit the buy button on a 500esp so have been playing catch up on this thread,is there any problems I need to know on the build?.this is not my first build ,I have previously built an esmart 600 which is no longer with me and an msh protos which I love to bits.I always fancied the esp and since I just turned 50 I thought I would buy myself a present.
I hope you won't mind me asking dumb questions from time to time as I progress with the build,going to be using kit based motor/esc and cyclic servo's and probably gy401/align ds520 on the tail (that combo works fine on the protos)

henry

[DoctorAudio]

You know take your time and get ur done.
Follow the manual. I didn't have a problem with the T-REX 500.
I am running a GY-401 and a 9254 tail servo. The 401 is easy to setup.
In non heading hold the pitch slider should be dead center.
Also make sure you what your geometry of the controls. It does affect how it flies!
Other than that have fun and good luck!
Elvan Wilson II

[jmpwnd]

Originally Posted by henryd123

hi there guys,I have just hit the buy button on a 500esp so have been playing catch up on this thread,is there any problems I need to know on the build?.this is not my first build ,I have previously built an esmart 600 which is no longer with me and an msh protos which I love to bits.I always fancied the esp and since I just turned 50 I thought I would buy myself a present.
I hope you won't mind me asking dumb questions from time to time as I progress with the build,going to be using kit based motor/esc and cyclic servo's and probably gy401/align ds520 on the tail (that combo works fine on the protos)

henry

Henry,

Welcome to the T-Rex 500 ESP! I just finished putting mine together this week. This thread and it's regulars have been a huge help to me in my build. Also, I would suggest going to helifreak.com and checking out Finless Bob's build videos. They were invaluable in getting me through the build. I think that the manual is very easy to understand, but Bob goes through every step and points on little subtleties that you might not have been aware of until it's too late. Also, he enforces proper build technique. The whole "understand what you're doing before you do it" methodology.

Finless T-Rex 500 Build
Finless T-Rex 500 ESP Nitro Conversion (Torque Tube build videos)

Good luck!

Cheers,
-->Justin

[hancockdw]

Located my 'tick'! It was in the tail pitch slider! Sure didn't sound like it! I assumed one or both bearings in the slider (called "bearing holder" in the manual) was/were bad, because you could feel them catching when turned, but once removed they seemed OK. If the sleeve ("slide shaft") that passes through the bearings and threads into the "metal T type arm" (where the control links fasten) is tightened too much, the noise and the roughness returns. I can back off the tension a partial turn and it disappears. Now I'm not sure if I need to replace the bearings, or other parts.