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Old 05-29-2012, 12:43 PM   #1
Racing_
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Default What upgrades on a T-Rex 550/600 for scale flying?

Hello.

I`m going to mount a heliartist 600 airwolf on my t-rex 550 (stretched to 600) and have some questions i need help with.

1. Is the align ESC good enough, or should i replace it? If so, what ESC is recommended, and how many amp?

2. Is the original motor good enough for scale flying?

3. Should i keep the torque tube, or rebuild it with belt?

4. What headspeed is recommended in scaleflying? How many tooths on the motor pinion should i use?

5. How long main/tail blades should i use?

Hope you guys can help me.
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Old 05-30-2012, 02:28 AM   #2
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1. Yes, works perfectly
2. Yes, works perfectly
3. Yes, keep it
4. Recommended - no clue, I run aprox 1600 rpm and very pleased with it
5. 600mm/95mm

Answers given based on using a T-rex 550 V1 Flybar, all stock electronics, stretched to 600, in a Century/Fun Key Bell 222.
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Old 05-30-2012, 05:01 AM   #3
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My answers may be a little different;

1. It might be, but the heatsink is poor, so if you close the fuselage in (ie. closed windows) and fly in a warm / hot climate (probably not an issue in Sweden, but certainly in Australia), it might get hot. The Align ESCs also have poor / non-existant governors, so if you plan to govern, it is not a good choice unless you will govern with the FBL (if fitted) controller. My experience with Align "soft starts" is that they do not give a very realistic slow spool-up (much too fast). A CC Ice 100 would be a far better choice (if running 8s or less).

2. It depends on if you can get a pinion small enough. Running the motor & ESC slower than about 70-75% of full throttle using a low throttle curve or governor setting is a recipe for something (usually the ESC) getting hot. Many opt for a slower (lower kV) motor for this reason. It should have plenty power (scale does not need lots of power), but may be too fast.

3. TT is fine.

4. Probably around 1600rpm with a 2 blade. The pinion will depend on your motor kV and main gear teeth, so no clue with this info. Eg. 1400kV motor x 22.2V (6s) x 0.9 (Efficiency) x 15T pinion / 170T main gear = 2470rpm at 100%, so running at 1600rpm would require a pinion with 1600/2470 x 15T = 10T so probably 11T to allow for governing (assuming a 1400kV motor and 170T main gear) - work it out.

5. Mains = 600mm, and tails may need to be longer than 95mm if you slow it down to a point of lacking tail authority.

Colin
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Old 05-30-2012, 02:19 PM   #4
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The helicopter is a t-rex 550 v1, flybarless with beastx. And i will stretch it to a 600 size to fit the fuselage.
My plan was to still use 6s lipo.

My motor is the original RCM-BL600MX that is 1220kv. Main drive 170t. So that should be:
1220kv x 22,2v x 0,9 x 16t pinion (original on the 550) / 170t main gear = 2300 rpm at 100%
So 1600 rpm would require a pinion size: 1600 / 2300 rpm x 16t = 11t pinion. Is this right?

I dont know what governor is, or what it does. So i have to google it. Is it recommended to use governor?

But if i choose a 11t pinion and use the original motor and esc, then i should get 1600 rpm main head speed at 100%? Is it recommended to have 100% on the esc? And will it affect my flight time if i have 100% vs 90% or 80%? (i know that with 80-90% i need a different pinion or a different motor to get 1600 rpm)

I live in northern Norway so temperature is not the big issue here. I want to have the windows in the model, so the cooling will be through the top and vent channels on the fuselage. Can i upgrade the stock esc heat sink? Should i mount a extra fan for cooling the esc?

Alot of questions, but i really need help in the beginning
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Old 05-30-2012, 04:21 PM   #5
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Governor is like cruise control in a car it will attempt to keep the headspeed constant at all loads. Just setting a flat throttle curve to 80% or 90% is not the same thing as the more you load it up the headspeed will drop. You don't have to run a governor but it better to try and keep a constant headspeed you can achieve a similar thing with a "v" throttle curve.

Your working for headspeed is correct.

I have fans in one of my models because its all closed in but not the other and a few other people have fans in them as well. You can get fans off Ebay in all sorts of sizes and voltages.
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Old 05-31-2012, 04:59 AM   #6
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I think you would be better using a 12T, so that you are not running the system at 100% throttle.

1220kv x 22,2v x 0,9 x 12t pinion (original on the 550) / 170t main gear = 1720 rpm at 100%, so 1600rpm would be 93% throttle or governor.

If your motor shaft is 5mm this may/should be OK, but if it is 6mm, I would suggest caution - I have had a 6mm 12T pinion shatter, and have read here about at least 2 others shattering as well - not enough metal between the hole and the tooth root.

So, if it is a 6mm motor shaft, it may be advisable to get a slower motor, or run a 13T pinion and slow it more with the ESC (86% throttle), or use a 164T Mod 0.7 main gear.

I would suggest thinking about a Castle Creations Ice 100 (an Ice 75 would be fine for scale flying as well) - about $120. It has a good heatsink, a great governor and a nice programmable slow spool-up (up to 40 seconds). It also has a datalogger which records headspeed, voltage, amps, temp etc.

One of the main benefits of a CC governor is that it will allow you to type in a headspeed of 1600rpm using the USB link, and the system will hold 1600rpm for the full flight (if you have calculated the speed using 3.7V per cell and your lipos are not stuffed).

A non-governed setup aiming for 1600rpm at the end of the flight would start at something like 1600 x 4.0/3.7 = 1730rpm because it varies with the voltage of the lipo. Or with a shallow V curve you would get closer to full stick towards the end of the flight as you would be increasing your stick position as the flight progresses.

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Old 05-31-2012, 09:29 AM   #7
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As i see it, i better change the esc and buy one with governor and fly with this so i can run with 1600 rpm all the way.

I dont know the diameter on the motor shaft, but i will check it out, thank you for the tip.

1. How is castle creations? When i was searching for a new esc about a year ago i found some posts about the esc taking fire. Have they fixed this?
I have owned castle creations esc earlier in boats and cars, and they have worked excellent. Easy to set up with the usb link.

2. Is this the castle creation ice100 you were thinking about?

3. How is it with power to the servos? Can i use the bec in the esc, and get power to the servos through the main battery? That would be the easiest solution.

4. About retract servo. How many should i use? Is it enough with one, or should i get two or three servos? What is your experiences here?
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Old 05-31-2012, 04:06 PM   #8
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1. It was the HV Ice ESCs that were burning, mostly 120HV. It has been very rare for a standard Ice to burn.

2. Yes it is, but I think that for the same $118 I would rather buy one from a reputable shop (Esprit has them for $118 as well. I don't know where you are , but you may get free shipping in the US).

3. I would not recommend using the internal BEC for a 550/600 heli. Either use a A123/LiFe battery direct to Rx (no regulator), or use a separate BEC.

4. I have no experience with retracts.

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Old 06-01-2012, 02:24 PM   #9
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I will replace the stock esc to get governor.

1. What is the best solution, separate BEC or separate receiver battery? Any opinions/experiences about this?

2. I have measured the motor shaft, and it is 6mm. What is the best choice here then? Use a 13 tooth pinion (86% throttle = 1600 rpm, how low can i go before the esc is getting hot and out of its "safe zone"?), get a slower motor or use a 164 tooth Mod 0.7 main gear?
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Old 06-01-2012, 05:58 PM   #10
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Personally I like a separate Rx battery - it lets me do most of the setup without any power to the motor, so no fear of a accidental spool-up. But it depends on your preference - it means 2 batteries to charge and worry about their state of charge, instead of one, but it also means that you have slightly more mAh for flying from your main lipo, and one less electronic component to worry about.

Usually running a CC Ice ESC at 86% would be fine, and a 13T pinion will cost you $1.25 (two for $2.50), so it is cheap and simple. Getting a 164T Trex 700 gear and KDE hub would cost you around $30-40 and you only get 3.7% slowdown (good of running 12s because the wider gear has more load capacity). A new motor is going to cost you $150 or more, so should really be the last resort.

Not too hard to think it through really. You choice is yours, and it is best to take any advice here (incl. mine) as a thought starter, research it yourself, and make your own decision. We can give you some advice, but it is always best not to believe everything you read on the forums.

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Old 06-01-2012, 06:23 PM   #11
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I always google and research alot before i buy something, and i really appreciate all your help and guidelines to get me in the right direction, it makes it alot easier for me to search and make up my mind

I will try the 13 tooth pinion then, at least buy it and see how thick the walls are.

I have googled a bit about bec vs battery, and i think i am going for a separate battery. Can still autorotate if anything happens with the esc to minimize the damage and the advantage of do the setup without any power to the motor.

- How many mah is recommended on the receiver battery? I have no clue of how much the servos use in power in one flight. And how many flights do you get before charging the receiver battery?
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Old 06-01-2012, 07:24 PM   #12
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A 13T pinion should be fine - I have used one for a while now on 12s.

I use two 1100mAh home made 2s batteries (made using 2x A123 1100mAh cells from Hobbyking). The reason for two is that I run JR RD922 & 1222 Dual power Rxs in my scale helis, so I connect up two separate batteries as the Rx has two power leads and has an automatic failsafe if one battery dies.

If you are going A123 or LiFe, be warned that voltage is not a good indicator of their state of charge, and I have even found the mAh put back in a bit variable, so be conservative. I easily get 6x 6 minute flights out of my 2x 1100mAh = 2200mAh batteries, although I think I have pushed it to 10 once.

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Old 06-02-2012, 04:49 PM   #13
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I have searched on my servos (align ds610 and ds620) and they are max 6.0v, and a A123/LiFe battery is 6.6v. Wouldnt my servos get fried? How have you did it?
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Old 06-02-2012, 04:59 PM   #14
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Hi m8
I have just finished building the exact same thing maidened 2 days ago

I am using stock motor scorp esc, seperate rx battery and another for the nav lights.

I used the 600 TT. The 550 frame i had to build up in order to get main blade clearance (but I'm also using a dfc head) I've also modded the top of the canopy do I can get batteries in and out without wrecking the canopy.

Until I get bigger blades I'm running the stock 550 at the moment and it glee very well. I had to add some nose weight to get the cog and now with flight lipo it weighs 5.1kg

There's a short vid of it on YouTube under martin353

Pm me if u need any help m8.


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Old 06-02-2012, 05:00 PM   #15
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O and don't worry about the servos. I did the same research and 6.6v is fine with them


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Old 06-02-2012, 05:18 PM   #16
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Perfect, then i will be using a LiFe pack directly in the RX.

Could you please post some pictures here of the Airwolf with DFC head? I have searched in days on google trying to find a Airwolf with this head, without any luck.
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Old 06-02-2012, 05:44 PM   #17
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Will do m8


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Old 06-02-2012, 06:03 PM   #18
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Pics m8.
Let me know if u want anything more specific or better quality.
Click image for larger version

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Old 06-02-2012, 06:32 PM   #19
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Quote:
Originally Posted by Racing_ View Post
I have searched on my servos (align ds610 and ds620) and they are max 6.0v, and a A123/LiFe battery is 6.6v. Wouldnt my servos get fried? How have you did it?
I run my Futaba BLS 252 and 451 (both rated for 6V) directly off the A123, and I have an Align stepdown before my BLS254.

I have heard that the 610s are OK, but I don't know about the 620 ? I seem to remember hearing about some people having problems with an Align tail servo running at 6V, but it may have been a 650 ?

Colin
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Old 06-03-2012, 04:31 AM   #20
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I searched for it last night, and it looks like it`s ok to run LiFe 6.6V unregulated to DS610, DS620 and DS650.

DS620
DS610/DS650
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