T-Rex 550 V2 DFC Largest Blades

[mcarter76]

I've taken good care of my T-Rex 550 DFC and have already flown it a full year without any mishaps. I initially opted for the 550 mm main blades as it uses the 600 head and boom. My only complaint is it flies a bit heavy. I started with the talon 90 and 600 mx motor, but recently upgraded to the KDE 550xf motor and hobbywing platinum 100 amp esc with fan.

It feels good with vbar gov and 12T pinion, but I'm wondering if it would fly a bit lighter and bigger with 570 or 600 mm blades. Do you think my esc and 6s 5300 mah 35c packs can handle it? I really like 6s btw.

[Smoggie]

The limit is usually set by the clearance between the tips of the main and tail blades at their closest point of rotation.
So you rotate until the blade grips of the main and tail are at their closest possible position. You then measure the distance between the main and tail grip bolts, that is the maximum combined main + tail blade length, not forgetting to allow 5mm or so for clearance.

So for example (making numbers up as i dont have a 550):

The distance between bolts is measured at 760mm and tail blades are 95mm

760mm - 95mm -5mm clearance = 660mm max blade length

[mcarter76]

Thanks for the info, but I should clarify that I already know that 600 mm blades will fit my model. My concern is if my current electrical is up to the task, i.e. battery, motor and esc. And if it would have better flight characteristics. I'm kind of cheap otherwise I'd buy a 600 or a Mikado or something.

[minatrix]

Just going off the manufacturers info the motor is capable of 125A continuous and the ESC is rated for 100A continuous. I'd be pretty cautious using them together.

[mcarter76]

Originally Posted by minatrix

Just going off the manufacturers info the motor is capable of 125A continuous and the ESC is rated for 100A continuous. I'd be pretty cautious using them together.

Thanks yeah I'll try to keep an eye on it. The ESC does have the fan installed and I have a spektrum temp sensor on it. It barely got over 100* F on a hot day with my test flight. I'm thinking that if the motor is rated for 125A continuous it doesn't mean it will always draw that much current continously - maybe for bursts.

So then would you recommend 600 blades with a larger ESC or not at all?

[minatrix]

Originally Posted by mcarter76

Thanks yeah I'll try to keep an eye on it. The ESC does have the fan installed and I have a spektrum temp sensor on it. It barely got over 100* F on a hot day with my test flight. I'm thinking that if the motor is rated for 125A continuous it doesn't mean it will always draw that much current continously - maybe for bursts.

So then would you recommend 600 blades with a larger ESC or not at all?

The motor lists a max peak current of 205 A, while the ESC has a max peak current of 140A. How much continous current it draws will depend on your setup. But certainly the ESC is not rated for the motor. Maybe you have anecdotal evidence of using this setup with success? It is preferred to have some overhead on the ESC side. Personally, I would not use that combo. If the ESC had logging and you could verify your amp draws were within the limits of the ESC, maybe. I really don't know much about how much you can push your ESC with an overrated motor. So many stories of downed heli's, I play that one safe.

As for the 600mm blades, nah, that's 12s territory. 570mm blades with 5300 packs and a 130A or greater ESC would probably be ok, but still the 35C rating on the packs is kinda low, and that setup is not known for being easy on packs. Check out the Goblin 570 forum for some good discussions on a 6s 570mm 5300mAh setup vs 12s 600ish 3000mAh bird.

Personally I would want to stay with 550, or go to a 12s 600, and use the battery as an excuse to get a 500 to go with it, but that's just me. If you could just get some 570 blades then sure why not, but you would surely need a bigger esc, and there wouldn't be a lot of bang for the buck, imo.

For me these decisions have usually come down to the battery. What battery do I want to run? I personally would not want to run a 5300mAh, and would much rather run a 12s3000 heli and have a 6s 3000 heli as well (gaui x4ii would be my choice). There are alot of benefits to keeping your amps lower. In a 12s 600, 35C packs are fine for most pilots, and a pair cost little, if any, more than a higher C 5000+mAh pack. Really it's all a matter of opinion and figuring out what actually works for you. If you decide to convert to 600 that HW V3 100A would be a great esc for the 500

[Staticxd00d]

I'm still new to this, so bear with me... but couldn't he possibly change the pinion to get a different gear ratio for the larger blades without laying all of the extra work onto the ESC to swing them?

[RC/DC_5000]

I would recommend that you ask other people who are flying extended blades on the 6s 550- what current they are logging. It would be nice to know their average current and their peak current with their blade size.

This will give you an idea of what to expect when making the disc bigger. Sure their are variations in current with different motors- but one thing that is promised to use more current is longer blades.

Its a constant added load on the motor... so the current goes up to torque them around and around. What kind of current are you using now.. or were you using on the Talon? I know the 730mx has ridiculously low current on the 550. The 600mx is pretty hot.

[mcarter76]

Yes was flying with Talon 90 and now have the HobbyWing Platinum 100 so unfortunately there's no log of max current draw. Previous motor was 600mx 1220kv.

[RC/DC_5000]

Well we can look at it this way. Your KDE 550xf is rated to peak at 205 amps for two seconds and 125 amps continuous. The higher your headspeed and the bigger the blades- the closer you are going to get to those maximum ratings. Its safe to say that your ESC is not ready to fully deal with that motor.

If it were me, I wouldn't test it. A 550 is a 550 for a reason. Its only on 6s. The 550 class is basically the breaking point for the largest helicopter for modern 3D at 22.2 volts. If you want bigger blades with bigger power... gotta get the 12s 600. Its a monster and runs current under 100 amps peak all day. It uses about 40 amps on average.

So there's a price to pay for the convenience of only one 6s pack. In all out 3D, the 550 just works better with the shorter blades... and in Aligns latest opinion- a shorter boom.

Now if you're just cruising around at lower headspeed and maximized gearing.. I bet you could get away with the longer blades. But that kinda negates having a KDE motor.

[SumOFparts]

What you got is a yacht(550 XF) - but you've only got a swimming pool to put it in (6s)...
@ 100a......
Some people are very happy with that arrangement - just to have a boat to stand on and sip champagne ......... most of us here are not......and nothin will change that.......

I would stick the 600mx back in - or move up to an edge 130LV - that way there is no chance of a Hitchcock moment.......

If you use kde and the 130a - get warranted lipos - they're gonna get the fulll test.....
And instal the most heavy duty electrical system you can - desoldering will be your constant enemy......you'll see.........

-

[SumOFparts]

In answer to original question - I find I can fly upto 550~570 on the 6S lipos w/600mx - without noticing any lameness....

When I go to 600mm - its really not even a sport heli anymore - flys slow and under powered - like a scale......

The 550 XF and 600XF motors will over come this - but 45c and under lipos will come down very hot........

-

[mcarter76]

I realize this thread is pretty old, but I wanted to revive this as I'm considering flying my 550 again and have decided to follow everyone's advice here and update the ESC to be compatible with the 550XF motor. I haven't flown it with the 100A ESC since the warning.

Here are the ESC's I'm currently considering, and the plan is to run the stock Servos off of the internal BEC. I don't like external BEC's that much. The other important thing is an rpm output for the vbar.

HobbyWing Platinum PRO V4 120A ESC (3S-6S)
http://www.helidirect.com/helicopter...0a-hv-esc.html

YGE 120 LVK controller (with heat sink) V2
http://www.helidirect.com/helicopter...ontroller.html

PHOENIX EDGE 130 AMP (32V 130 AMP) BRUSHLESS ESC
http://www.helidirect.com/helicopter...0-0099-00.html

At this point I'm leaning towards the YGE or HobbyWing as I like the big internal BEC and that it might fit under the battery tray. The 550 DFC is a bit tail heavy so some extra weight in the front helps.