Gaui 425 - setup confirmation

[Jack2010]

Hi Folks,

I'm new to this forum and this is my first post. I'm also quite new to heli and learning flying on 450 Sport.

I just have bought the Gaui 425 as I was looking into something bigger than 450 and more prospective for the future. I hope it was a right choice

As I mentioned I new to this hobby I dare to ask you for some help. My first topic is to get opinion on the heli config - is it right?

1. Kit: http://www.hobbypeople.com/shop/inde...ducts_id=17424
2. Motor: http://www.enjoyhobbies.biz/rc-helis...r-1500w-kv1100
3. Pinion: I have 13T and 14T - which one is better for the beginner with the above motor?
4. ECS: http://www.enjoyhobbies.biz/rc-helis...a-for-bl-motor
5. External BEC: http://eng.gaui.com.tw/d981119/html/...iew.asp?sn=853#
6. Swashplate servos: http://www.hobbycity.com/hobbyking/s...idProduct=9439
7. Tail servo: Align DS520 or Futaba 9257 (I have both and have not decided yet wchich one to use)
8. Gyro Align GP 750 and/or Flymentor like this: http://www.hobbycity.com/hobbyking/s...dProduct=10092 (also have not decided to use both - Flymentor to control the swashplate only or Flymentor alone to control all servos)
9. LiPo: two pairs of 3S Turnigy 2200 mAh 25C and 30C constant from my 450 in series
8. Lipomonitor: http://www.hobbycity.com/hobbyking/s...idProduct=7227
9. AR6200 with satellite
10. Main blades 425 from kit


All high voltage connections plan to base on XT-60. I only don't know what size of gold-type connection shall I use for motor-ESC...

I believe the only thing I'm missing here is the LiPo for BEC and I have no idea or experience what to use there.

I'm also a little afraid of the fact that maximum current of the ESC is 65A and the motor max is 75A


Any comments or suggestions are far more than welcome.

[Mikej]

Most of it looks good - however that motor is a power-crazy in-efficient thing and will probably burn the 50amp ESC out, this one might be better (I haven't heard any reports on it yet) http://www.hobbycity.com/hobbyking/s...trunner_1300KV . Servo specs look OK, but again I haven't heard reports

[ukgroucho]

Or just get the 425 FBL kit from HobbyCity... it's cheaper, pretty much full CNC apart from tail grips and you could set that up with a BeastX controller for less than messing with the 'normal' 425 CF kit and so on. Plus it has a more up to date motor and esc.
I guess the flymentor will act as a flybar-less controller anyway (?) so scratch the BeastX if you want the additional features of the Flymentor

[Ivor Hill]

Originally Posted by ukgroucho

Or just get the 425 FBL kit from HobbyCity... it's cheaper, pretty much full CNC apart from tail grips and you could set that up with a BeastX controller for less than messing with the 'normal' 425 CF kit and so on. Plus it has a more up to date motor and esc.
I guess the flymentor will act as a flybar-less controller anyway (?) so scratch the BeastX if you want the additional features of the Flymentor

Flymentor is not designed for FBL. Ivor

[Jack2010]

@Mikej - if I will limit thro curve to let say 90% will it help with this ESC?

[Mikej]

Originally Posted by Jack2010

@Mikej - if I will limit thro curve to let say 90% will it help with this ESC?

It's not the ESC that is the problem - it is the motor, use the same ESC buy a different motor - limiting the TC won't help unfortunately

[Jack2010]

OK, got it (I guess that if I have a motor that is OK I should be just fine, but if I have a motor with the power consumption issue as some people reported than I might get into trouble)

What about other questions:
- pinion: I have 13T and 14T - which one is better for the beginner with the above spec?
- what size of gold-type connection shall I use for motor-ESC - 3,5mm, 4 mm?
- what LiPo for BEC is recommended?

[Mikej]

Originally Posted by Jack2010

OK, got it (I guess that if I have a motor that is OK I should be just fine, but if I have a motor with the power consumption issue as some people reported than I might get into trouble)

What about other questions:
- pinion: I have 13T and 14T - which one is better for the beginner with the above spec?
- what size of gold-type connection shall I use for motor-ESC - 3,5mm, 4 mm?
- what LiPo for BEC is recommended?

Jack,

The challenge is that as well as getting hot and pushing your ESC too far, that motor will eat your batteries and kill them (particularly if you are using 2200 batteries) - it's just not a good motor for this application I'm afraid - very inefficient.

It's hard to say which pinion until you know which motor you are using - typically for a beginner you should be shooting for a HS of about 2,600 - 2,800 probably - if you look here http://www.gaui.com.tw/html-en/550_rotor_speed.html there is a very nice headspeed calculator that will allow you to check the different permutations.

Gold connectors - bigger is better - 4mm would be perfect.

I don't use a separate BEC lipo as I run a Dimension Engineering SportBEC off my main pack - I did run the Gaui BEC for a while with a 850maH 2S battery - which I didn't like it as it was another thing to remember to charge, so changed to the SportsBEC

[Jack2010]

Thx for the explanation; so what would be the recommendation - change the motor, ESC, both? - I read between lines that what you are suggesting is get rid of my 2200 LiPo, Gaui motor, ESC and BEC and replace it with new motor like the one suggested and 70-80A range ESC with integrated BEC as well as bigger LiPo's, am I correct?

I would say this can be my "long term plan" and I agree with it but...

...for the startup - can I try with my setup or it is more or less a must to change the motor and I have to face it? If yes, can I than keep the rest as it is (having in mind long term perspective as per above) and this will work for me (begginer) for some time?

In general - shall I get rid of this Gaui motor, or keep it for the future when possibly upgrading 425 into 550 TT, changing LiPo, ESC/BEC?

[torana74]

Jack,even though Mike is from no sunshine England,he is very knowledgeable in this. I would suggest to seriously consider what he is advising.
As with anyone when starting out, we all try to do things the cheapest way.. might not be the most economical in the longer term. Also consider, your optimal setup for a 425 might not be your optimal setup for a 550.
The best idea is to go for the most efficient setup possible. It will be nicer on packs,esc's,motors and ultimately you and your wallet.

Vas

[Mikej]

Change the motor - the ESC is fine (I use them on both of my 550s), it is the motor that is the problem - it is inefficient and very power-hungry. My personal favourite motor is the Z Power Z20A 980kV, available from Flying-Hobby for about $60. I have used this with 425mm, 475mm, 500mm, and 550mm blades - you just change the gearing, boom, rudder rod and belt. I have used 2200 batteries with each of these set ups (I flew on 2200s for the first 2 years and 2650maH for the past year). The blades that were "hardest" on the batteries were the 425mm - presumably due to the higher headspeeds needed, my favourite are the 500mm size. WIth 2200s you will get about 5.00 - 5.30 minutes on 500mm blades but more like 4.00 - 4.30 minutes on 425mm blades.

In summary don't get that motor, the rest is good and will give you scope for changing to 500mm or 550mm blades later - to be honest these are better for learning anyway. My recommendation woudl be to go for the Z20A motor, keep the Gaui 50A ESC etc., get the upgrade to 500mm blades (about $16 from Flying -Hobby for the boom, belt and rudder rod plus $16 for some wooden blades and try the heli with both size blades and see which you prefer.

If you use the Z20A 980 then use 14 / 50 / 20/ 61 gearing for the 500mm blades or 16 / 42 / 20 / 61 for the 425mm blades.

Mike.

P.S. I would not get an ESC with an integrated BEC - I use a separate BEC, it is just powered from the main packs rather than from a pack of it's own

[Mikej]

Originally Posted by torana74

Jack,even though Mike is from no sunshine England,he is very knowledgeable in this. I would suggest to seriously consider what he is advising.

Thanks (I think) - I got sun burnt last weekend

Originally Posted by torana74

As with anyone when starting out, we all try to do things the cheapest way.. might not be the most economical in the longer term. Also consider, your optimal setup for a 425 might not be your optimal setup for a 550.
The best idea is to go for the most efficient setup possible. It will be nicer on packs,esc's,motors and ultimately you and your wallet.

Vas

Surprisingly good advice for a sheep-sh@gger

[torana74]

Originally Posted by Mikej

Thanks (I think) - I got sun burnt last weekend

wouldn't be hard mate. You guys are whiter than feta cheese.The skin goes into shock with sunshine

Surprisingly good advice for a sheep-sh@gger

Ummm wrong colony mate. That's the kiwi's not so secret pasttime. We're too busy drinking amber fluid to bother getting out. Hence our football and cricket teams at the mo.


Jack, can't go wrong with the Z20 setup Mike is mentioning. Very efficient, packs will love you, long flight times. Unless you really want to go the 425 route, 500's will really be a nice setup

Vas

[Jack2010]

OK, I'm listening guys...

Just to be clear - the list I provided is what I already have, not what I am about to buy...

So, it looks like I need to replace/buy the engine first - this Z-Power/ Tonic-X sounds very suitable for the ESC you/I have (max 45 A vs. 50A constant of the ESC). Will think it over...

The rest of my spec will have to stay as is now for a while. I know that the bigger the heli the better for the beginner is and that is why I got 425 (Rex450 Sport I have already) with the ease and quite economic way to upgrade it up

On BEC - will it not give you substantially more flying time if the main LiPo are just for the engine and the rest is powered by 800-1100 mah separate pack?

So now need to find someone who will buy my Gaui engine Any idea on how much I can get out of it?

PS. I have no doubts that Mike is an expert...

[ukgroucho]

Originally Posted by Jack2010

On BEC - will it not give you substantially more flying time if the main LiPo are just for the engine and the rest is powered by 800-1100 mah separate pack?

No. You're carrying an extra 2S pack (and presumably a regulator for 5V/6V) which will weigh a LOT more than a decent SportBEC - and weight will affect even a 425.

Plus you need to remember that the SportBEC will be pulling very few amps from a 2200MaH 6S battery set (approx one third of what would be pulled from the 2S separate pack). Assuming that an 1100MaH 2S pack is good for 3 flights (and it may be more) you'd be looking at consuming 800 - 850MaH (80% rule) out of a 2S over 3 flights = 275MaH per flight.
Divide by three (6S / 2S) means less than 100MaH from your 2200MaH flight pack per flight. That's probably pessimistic and it does not factor in the cost of carrying extra weight with the flight pack and regulator.

Bottom line maybe 15 seconds of flight time.

[Jack2010]

Once ukgroucho wrote it is clear even for me thx

So now need to sell Gaui motor and Gaui BEC and need to invest into new BEC and motor ...

Will this one work for me: http://www.hobbycity.com/hobbyking/s...dProduct=10313

Speaking about the motor - Mike suggested: http://www.hobbycity.com/hobbyking/s...trunner_1300KV
as possible solution but... I went thru spec and I can see that the shaft is only 14mm long, while the Gaui original is 25mm - will it be an issue?

How about this motor: http://www.hobbycity.com/hobbyking/s...28600_class%29

[Mikej]

Originally Posted by Jack2010

Once ukgroucho wrote it is clear even for me thx

So now need to sell Gaui motor and Gaui BEC and need to invest into new BEC and motor ...

Will this one work for me: http://www.hobbycity.com/hobbyking/s...dProduct=10313

Speaking about the motor - Mike suggested: http://www.hobbycity.com/hobbyking/s...trunner_1300KV
as possible solution but... I went thru spec and I can see that the shaft is only 14mm long, while the Gaui original is 25mm - will it be an issue?

How about this motor: http://www.hobbycity.com/hobbyking/s...28600_class%29

The shaft on the Gaui 850kV that was standard on the 550 has a 17mm shaft - 14mm should be OK (no guarantees - not tried it). The typhoon that you linked to has a max current draw of 60A which may push your 50A ESC too far, also the motor is a bit heavy at 269g - they are saying that it is a power step up for the Trex 600 which is bigger than the H550

[Mikej]

Oh, by the way - I kept my Gaui BEC and use it a lot for set up. I connect a small 2S battery to the BEC and use it to power Rx's, servo testers etc. - it's quite a useful thing to have around.

[Jack2010]

Originally Posted by Jack2010

Will this one work for me: http://www.hobbycity.com/hobbyking/s...dProduct=10313

So, what about the above BEC?

[Mikej]

Originally Posted by Jack2010

So, what about the above BEC?

The spec looks OK - I have no experience of it however