700 My New T-Rex 700X Build

Smoggie

Well-Known Member
Phil, those Supra X connectors look great. Only thing i'm curious about is why the need for extra wire on the series connection between batteries.. Is that because the connectors on the batteries cant be couple directly? (they can with normal bullets)
 

Heliman450

Well-Known Member
Phil, those Supra X connectors look great. Only thing i'm curious about is why the need for extra wire on the series connection between batteries.. Is that because the connectors on the batteries cant be couple directly? (they can with normal bullets)

Hi Steve, I was following a downloaded diagram from the Supra X website (in the absence of your photos :biggrin1:) as shown below. When I measured the battery cables with the Deans connectors, there was not enough free play to give a comfortable connection. However, the link wire only needed to be about 2 cm long, too short to give a good basis for soldering the connectors. It seems to work ok even though it's a bit long.

Battery Cables.PNG

Battery Cables.PNG
 

Smoggie

Well-Known Member
Phil, the connectors in the picture are two pole type, so you need a link wire. With single pole bullets usually the positive of one battery would simply connect direct to the negative of the other. I can see from your photo that the wires are long enough to do that without an extension. Sorry for being a bit late in the day with the photos but in post #62 I showed the arrangement.

I'm guessing the difference in your case is that you have used female connectors on both + and - battery wires? This obviously makes them impossible to connect directly, but it does have the advantage of being impossible to connect the two wires in a dead short (i've tried to do that before, not pretty!).
 
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Heliman450

Well-Known Member
Hi Steve,

I don't have any batteries with male and female connections. They are all female and the corresponding connectors are both male for the ESC and the charger cables. I have Deans and E-Flite (I think that's their name) and they follow the same concept. The E-Flite have a different shaped plastic holder to prevent the dead-shorting and Deans the 'T- shaped configuration.

Supra X's diagram also clearly shows this, too. My assumption has been that this is the correct wiring standard. That's why I have made a male-to-male link wire as the 700X will be my only heli with two 6 cell batteries. I want to continue to use my batteries for both helis and hopefully also for the Velos-Rotors 880 if that wish becomes reality. At that point I'll purchase more batteries and renew any that are showing signs of puffing along the way, my target being to have at least two sets for each heli if I take all three to the field. I see that as a total of 14 altogether. That's quite an investment in batteries and maybe I'll accept a lesser number and restrict my future desire for two sets each.

Finally, I don't have exactly the same connectors as those in the diagram but I've followed the same basic principle.

Sorry if I missed something along the way.
 

Smoggie

Well-Known Member
Yes, on many two pole connectors like Deans, XT-60 or the Supra x they have both + and - connectors on the battery 'same sex'. The plasic case of the connector will in such cases be designed so that you can't accidentally connect in reverse polarity.

Usually with bullets they would be wired one male and one female. This prevents connection with reverse polarity (i.e. the + on the ESC and charging lead can only mate with the + on the battery and similar for negative). If both connectors on the battery are female then it is possible to connect to the ESC or charger in reverse polarity. The downside with having one male and one female on the battery is that it is then possible to accidentally short the battery by connecting it's + and - together... So each method has it's risks.

These are the batteries I most often used, you can see that they come with one male and one female bullet (male on negative female on positive):

t5000-6-30.jpg

t5000-6-30.jpg
 
Nice maiden flight, I prefer that head speed.

Is the tail holding on punch outs?

Tail was holding ok but not as crisp as I'd like it but increasing gain fixed that. The initial headspeed on first liftoff was about 1700RPM which was a bit too low for me. During the flight I increased it to maybe 1900RPM which was much better.
 
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D.O.G.

Goblin 380 Supporter
That's definitely a sweet flying feather you guys have:drools:. I can't afford the bird but I can enjoy the videos/pic.:popcorn:
 

Heliman450

Well-Known Member
Yes, on many two pole connectors like Deans, XT-60 or the Supra x they have both + and - connectors on the battery 'same sex'. The plasic case of the connector will in such cases be designed so that you can't accidentally connect in reverse polarity.

Usually with bullets they would be wired one male and one female. This prevents connection with reverse polarity (i.e. the + on the ESC and charging lead can only mate with the + on the battery and similar for negative). If both connectors on the battery are female then it is possible to connect to the ESC or charger in reverse polarity. The downside with having one male and one female on the battery is that it is then possible to accidentally short the battery by connecting it's + and - together... So each method has it's risks.

These are the batteries I most often used, you can see that they come with one male and one female bullet (male on negative female on positive):

View attachment 17001

Hi Steve, you've convinced me. I'll change my battery negative connections to male. My reasoning is that it's the MOST safe option. I think it's highly unlikely that my progression into senility will cause me to join the connections of the same battery but maybe my longer term familiarity could lead me to join black to red or vice-versa. It should take me around 15 minutes each.

Thanks for alerting me to it.
 

Smoggie

Well-Known Member
Truth is Phil that with bullets you do need to constantly be careful of cross connection, they aren't inherently safe in the same way two pole connectors are. One thing (once you have swapped to alternate polarity); when connecting series batteries up on the helis always connect the wires from the ESC first. Only when the ESC wires are both connected do you connect the series link between the two batteries. Done this way it's impossible to accidentally attempt connection of the + and - of the same battery. The way the batteries are placed on the Trex it shouldn't really ever happen but it's still a good habit to get into

I learned this lesson the hard way:
sparks.jpg

sparks.jpg
 

Smoggie

Well-Known Member
More videos as promised:

2nd flight - all seemed to be perfect at this point:

Wobbly spoolup on third flight attempt:
 
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Heliman450

Well-Known Member
Hi Steve, that's really scary! Here is a photo of the new version. I think the Supra X look extremely purposeful and robust. I decide to keep the orange holding clips to highlight that the connections are the links to the two batteries. Of course, I needed to change the charge leads, too so it took me a bit longer to get through than I thought. Also, my soldering station is somewhat on its limits with such high gauge wires and I decided to cut off the connectors and will buy a stronger unit to clear out the old solder and piece of wire. Here goes...........

001_IMG_1455S.JPG

Photos to come of the next steps.

- - - Updated - - -

So here they are. Mounting the gyro as first step.

#1 Top mounting with connections 007_IMG_1462S.JPG #2 Side mounting - connections don't fit 006_IMG_1461S.JPG

#3 Current view shown in software 005_IMG_1460S.JPG #4 Mounting as currently in the software 004_IMG_1459S.JPG

In my view photos 3&4 is the optimum location for the servo wires to enter the unit. I'm open to suggestions on the top mounting, which I understand Steve used for his gyro.

001_IMG_1455S.JPG

004_IMG_1459S.JPG

005_IMG_1460S.JPG

006_IMG_1461S.JPG

007_IMG_1462S.JPG
 

Smoggie

Well-Known Member
Phil, If the wires reach then perhaps option #2 is the best compromise? I'm not so keen on standing it on it's end as it might be difficult to make secure, the very last thing you want is the FBL unit coming loose and flopping about, that will spoil your day for sure.

My Vbar is a bit different as it has a remote sensor so the sensor went in position #1 but the main 'box of tricks' is side mounted
 

Heliman450

Well-Known Member
Phil, If the wires reach then perhaps option #2 is the best compromise? I'm not so keen on standing it on it's end as it might be difficult to make secure, the very last thing you want is the FBL unit coming loose and flopping about, that will spoil your day for sure.

My Vbar is a bit different as it has a remote sensor so the sensor went in position #1 but the main 'box of tricks' is side mounted

Hi Steve, I haven't finalised my decision on this yet.

I wanted to check the Axon software out as they claimed 24 options for the orientation in their summary. That's where the position in photo #3 came from, it took me as being a bit unusual, too. As soon as I saw the location of the pins in the unit I thought it would turn out a bit of a challenge. I could secure it on two edges, not just the bottom one. I still haven't given up on a position behind the main shaft either.

I also need to think about the Jeti Rx. position. There is a wiring loop included in the Axon pack but this isn't long enough from what I can see and may end up buying the longer version. Now that the main power situation is resolved, I need to spend some time with the other wiring options. #1 just seems so close to that monster motor in my opinion and the unit is actually tipped back at quite a sharp angle that isn't shown in the photo. The servo wires just aren't quite long enough and it's made worse by the rubber covers alongside the connectors.

All feedback much appreciated.
 

trainrider06

Active Member
Phil even though that first position up in front of the motor seems the most practical, its kinda a worrisome place because of the proximity to the motor. My 450 Dominator ESC wires to the motor sit close to my motor, I am always checking the distance and worrying about it. But that may be the most practical place for it, or on the side. I wouldn't mount the thing on the end either like Steve said, it would be kinda worrisome of the stability of it on it's end. I'd wonder about how firmly it would be also to where it moved around a bit causing vibrations or slight movements affecting the stability of the unit to do its job also.

- - - Updated - - -

More videos as promised:

2nd flight - all seemed to be perfect at this point:

Wobbly spoolup on third flight attempt:

Well Steve except for the chicken dance there for a bit that it did, it looked to be flying very nicely. That would for sure be a worry for me in the back of my head if you cannot pin point the exact cause of it freaking out on ya! But sounds like your gonna cover the bases on it on the rebuild.
 
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Heliman450

Well-Known Member
Hi Rodney, thanks for the feedback.

I'm planning to go to my workshop today and seriously test out the options for what I consider the best cable runs. I measured up the Axon and the base gives 12cm2 area to stick it down with and the two edges only half that, so it needs something extra to satisfy me that an end mounting is secure enough. Up to now, I've been thinking of installing it with no servo lead extensions but it's beginning to seem that won't be possible up front. Rear mounting is the only position I see works on that one but then the ESC and Rx. wires need extending instead.

I'm not under pressure to rush this as I've ordered up a clever box of tricks to programme the ESC. It also says in the downloaded ESC manual that one shouldn't power it up for the first time with anything other than fully charged flight batteries. If I hadn't read that, I would probably have been tempted to start working with my small battery just to give power to the gyro, so better that I haven't powered the heli up yet. The Axon can take its power supply from the USB to update firmware and register the unit with the software for use. Better than my Spirit Pro.

I'll keep you in touch with developments.
 

Heliman450

Well-Known Member
Hi all,

I asked Align about servo frequencies having not found them for myself. Here's their feedback.

'DS820/DS820M/ DS825/DS825M Frequency are 330 hz and Tail Pulse Length are 1520μS'

Bye now!
 

Smoggie

Well-Known Member
I hate extension leads and try to avoid them whenever possible. If the edge mount really does work out best for wire routing (and that orientation is supported in the software) then it would be relatively easy to make an 'L' shape bracket from a bit of aluminium or similar that would allow the Axon to be secured by it's base rather than by it's edge?.. That should work pretty well
 

Heliman450

Well-Known Member
Hi all, here are a couple more photos of another option that works without extending any of the leads from what I can see at the moment.

#001a 002_IMG_1465S.JPG #001b 001_IMG_1464S.JPG

It's all temporary with nothing checked for accuracy as to which connection is plugged in where. The tail boom has a +5 degree angle from the ground so, of course, the gyro needs to be parallel with the boom and main rotor rather than the ground as it is in the photos.

001_IMG_1464S.JPG

002_IMG_1465S.JPG
 

Smoggie

Well-Known Member
That looks like a pretty good option Phil. I managed to install the Vbar in the forward position without any extension leads but the end orientated connections helped.

Today's good news.. i think I've sorted out the spare parts for my repairs. I've found someone selling a new unflown 700X airframe + blades and motor for a decent price. It's more than the spares would cost me but I dont have to wait for stock and it gives me a whole spare airframe plus I can perhaps sell some of the bits that i dont need (like the motor etc.) I'm keeping my fingers crossed until i see it firsthand but in the photos it all looks as new.
 
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