MD 7/8 6S Setup?

[canadien007]

Has anyone setup their MD 7 for a single 6S Lipo?

There's one available locally and I was thinking if it's possible to setup this bird for low rpm on 6S.

Thanks

[Keyrigger]

Is it powered by a 530kv motor, by chance?

Don

[canadien007]

Originally Posted by Keyrigger

Is it powered by a 530kv motor, by chance?

Don

Hey Don

You know exactly which one I'm talking about
Before I purchase that heli I wanna know if I can go with a 6s setup. of course a 530kv motor is not going to work, I'm going to have to swap it for another one.

In terms of gearing and all that, what other changes would I need to do?

Will the stock gearing work fine?

[Keyrigger]

That heli is a really good deal as I own one myself. Technically, you could use the 530 motor with the existing gearing and you would end up with a rotor speed (governed by the ESC) of 1054rpm. I fly mine at three speeds, 1000, 1100, and 1200 but the motor is specifically set to get those speeds. I am using the stock 13/121 gearing but when I change the boom to the 800 size with blades to match, I will be dropping to the 12t pinion. If you are planning to change the motor, you could do things a few different ways. Presuming you want to keep to 6s, you could up the motor to a 650kv that would give you just short of 1300rpm. Remember that this helicopter is not a featherweight and will need some decent power from the motor, even on 6s. Look for something over 3300 watts to fit the bill. I found one, the Scorpion 4235 630kv motor that puts out over 5300 watts and can draw up to 160 A. That's just one. The motor is not cheap and it was truly meant to be used as part of a 12s system. I am never sure how much power output a motor designed to run up to 12s puts out when run at 6s level. At least you have one motor to look at aside from the existing motor which can be used but at lower rpm. My own motor is the KDE 295kv motor which has a staggering output of up to 7125 watts normal and 12800 watts peak power. Crazy isn't it? What I did find interesting is that both the motors I mentioned are the same retail price. I would dearly love to buy that helicopter but I don't have the spare coin or it would have disappeared a long time back, lol. Good luck with your choice.

Don

One last thing, the gearing is not Mod. 1 but Mod. 1.2 so gears cannot be easily found outside the factory 12, 13, and 14t units.

[canadien007]

Thanks for the detailed response. low rpm IS what I'm looking for.

Don't do 3d, actually, CAN NOT do 3d hehe

[Keyrigger]

If you're successful in getting the MD7, put on your wish list the removable battery tray upgrade. Matt is great to deal with and if you have any questions that can't be answered here, he can. I am using the Bavarian Demon 3X as I hope I am well beyond needing bailout. Most of my flying is very low level and no matter if I had it or not, my low flying makes a recovery nearly impossible for any system to handle. The setup I have is extremely quiet in the air so for most of the flight, you can barely hear it, especially over 75 feet. Doing a big air loop will make the blades work a bit in the recovery and my favourite sound is when I come in for a low angle attack landing. The blades sound amazing. I am using the fan cooled version of the 160 but I don't have any data without it. Since it draws so little current, the ESC never really heats up and I have flown it down in Florida during 90+ degree temps and it barely got over 100F. Hope you get it.

Don

[canadien007]

I believe the way that comes with the heli is an Edge 160. does that sac have a built in governor?

Its equipped with a v1 icon which has a governor as well correct?

[Keyrigger]

The Edge 160HV has governor capability and if you have a sensor that the Ikon can use, the ESC does have an input that can be hooked up to the receiver/gyro. I only have used the governor features in the ESC even though all of my flybarless gyros have governor capability. So far, the Castle governor has met all my requirements in spades. Have you bought it yet?

Don

[canadien007]

Originally Posted by Keyrigger

The Edge 160HV has governor capability and if you have a sensor that the Ikon can use, the ESC does have an input that can be hooked up to the receiver/gyro. I only have used the governor features in the ESC even though all of my flybarless gyros have governor capability. So far, the Castle governor has met all my requirements in spades. Have you bought it yet?

Don

no, I haven't purchased the heli yet. I was going to a couple of days ago but then I decided to take the wife and kids down to Orlando, Florida.

Ended up going to Disney. boy did it turn out to be an expensive 3 day trip

[Keyrigger]

I feel your pain. I don't think the MD7 has sold yet so there may be hope. I've been busy building "Frankenheli's" to suit where they are going to be installed. Take care.

Don

[Curt S]

If you miss the other one I will have a listing up for this tonight or tomorrow. It is a V1.

[3drcbuilder]

I'm new to electric and am currently building an MD 600. However, I have just purchased a second hand MD 700 set of mechanics and am interested in a somewhat lower head speed than the norm. I would love to be able to run a 6s system but I am a real dummy when it comes to electrics.

I've read threw this post several time and to be honest not a lot of it I don't understand.

I'm thinking a max rpm of 1850 with the idle up's at 1600 and 1700.

What motor would I need.

[Keyrigger]

Although quite possible, running the MD7 on 6s is a bit like putting a Chevette engine in a Buick Electra 225. I presume that your speeds noted are for the MD6, which can easily be obtained with an 1100kv motor. From personal experience, an MD7 at 800rpm is a bit wobbly and can lead to some interesting shakes as it spools down. 975rpm is not so bad but the spool down is still a bit of a bear. 1100rpm is about as low as I would take the MD7. I am awaiting a new boom and struts to convert back to an MD8 and it runs fine with Rotor Tech 810's down to 750rpm but slightly faster is a better way to go. If you purchase a "free-wheeling" ESC, you can lower the speed without worry of overheating the ESC. I chose my motor to give me the required speeds with the 12 and 13t pinions. I should run with the 13t pinion but I am ok with the highest low speed for the MD8 setting.

I have set a scale 700 chassis for my Jet Ranger to run at 1200, 1300, and 1400rpm and will decide the best range when I get it in the body. It flies great at those speeds and any 700 will do so. I also have a 600 that I am running at lower speeds but will most likely keep it around 1400rpm. This one is a 12s system but if I was to convert it to 6s, I would use an 890kv motor to get the same 1400rpm speed. it can be hard to decide what to do but if you have a specific rpm range you want to run at, and on what helicopter, let me know as I can help out with the motor and pinion choices. Take care.

Don

[richord]

How do you balance the heli when running on 6S? I have used some lighter 12S configurations and had the heli tail heavy.

[Keyrigger]

Very simple, install the 12s pack but only run it with one battery. No matter what, you need to balance the helicopter so you might as well make it simple and put the second pack in there. You will have little luck trying to move equipment around the helicopter in order to balance it without adding additional weight above the single 6s pack.Have fun with it.

Don

[richord]

Thanks. That would work, but it's unfortunate to have to carry the extra weight. Ok for scale, but not for mild 3D.

I do like the side-by-side battery design for 12S, but the linear battery pack designs on other heli's allow a single 6S low head speed.

I will keep this one at 12S and try another 700 at 6S.

[Keyrigger]

I don't know of one inline that would allow you to use one battery without the other one in for balance but then I only have used my 600EFL Pro with one 6s pack but needed the second one to get the correct balance. There is an inline battery tray that is an optional purchase. That might allow you to push the battery much further forward and allow you to get away with a single 6s pack. Have fun.

Don

[richord]

I tried a single pack sideways all the way forward, just to see if it would balance and it doesn't. Granted, I didn't try the heaviest pack I have, but you can't fit the canopy on anyway.

The Synergy E7 can fly with a single 6S and the logo 690SX can also. They are some of the lighter helis that can run 700mm blades. I'm sure others with inline battery configurations can as well. I have a Synergy E7. I will try it out on that one to see how I like it. And use the MD700 on 12S.

Here are some videos:

Synergy E7

Synergy E7 - Extreme Low Head Speed (9 min 52 sec)

Synergy E7 Gens ace 5300 6s Mario D. (4 min 37 sec)

Logo 690SX

Logo 690SX 950rpm Low Headspeed Flight (4 min 45 sec)

[darkfa8]

Trying to fly an MD7 on 6s will require very heavy duty gear.

Scorpion motors are not efficient and will produce a lot of heat instead of outputting it as more power.

You'd also need a high-C rated battery that provides very low cell resistance.

And, a high current ESC, 160-amps+

This model size and weight, even with all of the tricks I know wouldn't do too well on a 6S setup.

In the very least, I'd maybe suggest a 8s or 10s to help keep the amp draw and heat down for the application.

You can't just run every size, or these larger size models on 6S well just because someone with a 12s setup, disconnects one battery. You'll eventually cook your motor, ESC, and/or battery.

If you're still dead set on 6s, then surely give it a shot, but I strongly advise against it.