Trex 700 6s Surprisingly Good

[Guest]

I’ve been messing with low headspeed, low s setups for a while but never really cracked it with bit boring or not feeling locked in. This is using a Trex which maybe isn’t the best platform fo this. Fortunately over time Align has lots of options for tail ratios, head dampers and so on so I’ve kept on tinkering.

Anyway today is the day I think I’ve cracked it (for me).

Stock Align 700 V2,
Nitro Pro head dampers,
Sped up Tail it’s about 5.0 to 1,
Pyro 650,
Futaba servos and Neo,
Zippy 4000 (nothing fancy).
AUW RTF 3.95kg.

I’ve been aiming for TDF weight, almost there prob need to save another 200g but tbh it doesn’t need it.

Just got back from the field, I found anything below 1800rpm a little laboured for my liking. Flyable but no snap. At 1850 it’s great, quick, changes direction superbly, and planted. Leaving 30% in packs yielded 4:45. Electronics cool and lipos barely warm. Max amps under 100 so generating about 3.1hp which is nitro territory.

2050 rpm is very snappy.

So if you want a decent flying 700 on 6s it’s perfectly doeable and fun. My days of electrics weighing over 5kg and mega headspeed are over for now but tastes change.

Aim was nitro power and single pack and call that job done :-)





MJ

[trillian]

Cool! I have found the sweet spot with headspeed that suits my flying is about 1300, give or take a bit. My lightest 700 is the Kasama Faifa, which if memory serves, is about 3.4kg without any flight packs (and it's 12s). If I fly it with a pair of the lightest packs I have, like 2600mah, it will be something like 4.26kg and it feels very floaty. If I converted it to 6s it could get into that weight range (under 4kg) with a single Zippy compact 4000 pack.

I was amazed when I first tried the 2600mah packs on the Faifa and it worked great. I just always had this mindset about power setups for 600s, 700s etc.

[Mike Sanders]

Very interesting. Thank you.

What motor did you use and what gearing?

I am thinking about doing a (relatively) lightweight one on 12 s. I have an Align BL600 MX motor with packs of 2700 to 3000 mah. Do you think they would manage? I only fly around, no 3 D.

[trillian]

I have used 600mx's in lots of 600 size helis and it has plenty of grunt, and it occurred to me that it should be more than capable in a low headspeed 700.

The Faifa has a rewound Hacker motor (about 420Kv) and I can fly about 6 minutes on a pair of Turnigy 2650s or Gens Ace 2600s and it balances fine because the battery tray arrangement allows them to be far enough forward.

At 1300 I can still do all the moves I always did, no change in my flying style needed. Lower than that and it takes some getting used to and more collective management. But for scale type flying, hovering and circuits etc. you can easily fly at 1100 or so, but you may need longer tail blades.

Very interesting. Thank you.

What motor did you use and what gearing?

I am thinking about doing a (relatively) lightweight one on 12 s. I have an Align BL600 MX motor with packs of 2700 to 3000 mah. Do you think they would manage? I only fly around, no 3 D.

[Mike Sanders]

I have tried my (full weight, 5400 grams) 700 at 1300 rpm. It was not really viable. It would hover and do the most gentle of circuits but anything more and it struggled.

If it were to be 1500 grams lighter I am sure that would be a different scenario.

[trillian]

Well, what I found is that I had to increase the pitch range. So when I was running at 1800-1900 I was fine at +/- 10 degrees of collective. But lowering the headspeed down to 1300-1400 required upping the pitch range to around 13.5 / 14 ish.

I have tried my (full weight, 5400 grams) 700 at 1300 rpm. It was not really viable. It would hover and do the most gentle of circuits but anything more and it struggled.

If it were to be 1500 grams lighter I am sure that would be a different scenario.

[electricsceadu]

What do the batteries come down like?
because if we think back to the original trex600e on 6s they got the packs nice and hot

[Guest]

Barely warm to the touch. It’s only pulling about 90-100 amps.

MJ

[trillian]

Ya know... I was thinking the exact same thing, how far it appears we have come in electrics and LiPos etc. But these days, running a
light 700 on 6s, even at headspeeds of 1800, has become common and is time-tested.

I was just thinking earlier - how the original Trex 600 was notorious as a pack-killer, and my best guess is that LiPos have just become much much better now.

What do the batteries come down like?
because if we think back to the original trex600e on 6s they got the packs nice and hot

[Guest]

After enjoying the single pack Trex so much I decided to make a custom frame set and take advantage of the setup a little more. I’ve shaved nearly 300g off and raised the battery almost in line with the boom. It’s a modular design and turned out really well.

RTF with pack as shown 3.7kg







And just back from the field. Def improvement over stock you can tell some mass has been moved upwards, tic tocs endless and effortless, rolls axial with very little work. Super happy with this, can see it been my go to machine just so easy.






MJ

[trillian]

This is truly outstanding work! Very well done