bandicootf16

Hi Brenner

Thanks for the very detailed description on the system resonant frequency. I think you see this in a heli when running the blades up. In this case once the rotor system is through this resonance it is no longer a problem as the head then runs at a constant rpm. As we don't run constant rpm systems the prop is constantly passing through this resonant frequency point so i guess a lower rpm point where this resonance occurs means less force is generated and the system is able to handel this without instabiliy. I hope my understanding is correct. As you say the smaller motors used in this system should allow plenty of mounting space.


That is an impressive amount of flights in a season. If the service interval was that long it would be a great achievement.

You mentioned that you used the Emcotec dual battery rx switch. Is that the one you use a magnet to turn on and off. It looks like a good set up but do you find it a hassle to us the magnet. I guess you wouldn't want to loose it.

David

Brenner

Hey David,

All rotating systems have resonances in their structure. I'm sure helicopters are no different. Most of my experience comes from designing washing machines.

I am using the Emcotec switch that requires a magnet to turn on and off. What I have done is embed a magnet in the end of the hex key driver that I use to loosen my canopy screw, so I have two tools in one.

Brenner ...

Jason Arnold

A few Brenner contra driven models at Gunnedah last weekend.
Shayne Lysaght flying the Epic, myself with the Allure and Peter Pennisi with the Dejavu.

Cheers,
Jason.

Brenner

Hey Jason,

Your planes look good!

By the way, I have just gotten back from test flying Shayne's custom wound Kontronik Pyro 600 motor with my V4 Drive, and I am very, very, happy with it.

The thermal performance is Excellent! I started out running an 8.3:1 gearset (the motor is rated as 1060 rpm/V) and I was pulling 65A with a motor case temperature after flying of about 140F (60C) with a 90F (32C) ambient temperature.

Then I switched to our standard 6.75:1 gearset, and I pulled about 100A. I thought this might be a little high to start out, so I ATVed my throttle back until I was pulling about 80A. This time I had a motor case temperature of 150F (65C) after flying. Then I removed the throttle ATV, and flew with a 100A draw, and then the motor case temperature was 158F (70C)

These temperatures are very reasonable, considering the 90F (32C) ambient temperature, and I would never expect to see the case temperature go above 175F (80C), even if the ambient temperature went over 100F (40C).

I was pulling about 3500W max by the time I finished, and I had more than enough battery to complete the AMA Master's pattern using 5100 mah packs, so there is nothing wrong with motor efficiency either.

Now, I'm sure that a lot of people are wondering why I'm so pleased with all this performance. Well, the reason is that the Kontronik Pyro 600 motor only weights 220g. This compares with 290g for the Kontronik Pyro 650, 380g for the Neu f3a motor, and 412g for the Hacker C50 motor.

We already save about 50g just on the V4 Drive alone, and we were planning on saving an additional 90g by using a Kontronik 650 motor instead of a Neu motor. However, it looks like we can add an additional 70g due to the additional weights savings from using a Kontronik Pyro 600 motor.

This means that our total savings will be 210g, and with this we can expect an all up weight of around 580g. This weight includes the Drive, the motor, the spinners, and both props. It doesn't include the rubber mounts.

I think this is more than competitive with any single prop setup out there.

Brenner ...

ram_z

Very nice Brenner!

looking forward to install the V4 in my next BJcraft project!

bem

My Feedback: (1)

Hi,
Just curious, Kontronik Pyro 600 outrunner has specification of coping with continous power of 2000 watt and Kontronik Pyro 650 continous 3000 watt.
What peak watt and for how long will the Kontronik Pyro 600 cope with?

/Bo

Brenner

Hey Bem,

Determining the intermittent power rating is a little more complicated in that it depends very much on the application, the duty cycle, and the ambient temperature.

The testing I did over the weekend was my attempt at trying to do this, and based on what I saw, I think that a 3500W intermittent rating, as measured on t the ground with fresh packs, is very reasonable for this rewound Pyro 600 motor, in a Contra V4 application.

My installation is very typical as far as venting is concerned, and my flights didn't use any throttle management either. I also finished my flights with a couple of full throttle passes to make sure that the motor case temperature would peak just before landing.

My duty cycle was, "one flight in the air, and one flight on the ground", and the ambient temperature was 90F (32C).

Given all this, my motor case temperatures seemed to peak at about 158F (70C). Which is way under what the motor can actually handle. Kontronik claims that the magnets are good for 150C, and the wire that was used for the rewind was good for 300C, so I think we are more than good.

Another way to look at this is to specify the mah consumed per flight, and in this regard, I consumed about 4500mah during an 8 minute flight, which is probably more than most pattern flyers will want to consume.

One other thing that I have so far failed to mention, is that the Contra V4 Drive/spinner assembly clamps directly to the motor rotor shaft, which allows it to function as a sort of "heat sink", and the spinner was noticeably warm after I landed, as compared to the spinner in a typical V3 installation.

I know this because Mike Gaishin was flying with me using a V3 Drive, and his motor (1515 Neu motor at 380g ..) landed hotter, and his spinner landed cooler. (I can't report actual spinner temperatures because the aluminum surface messes up my laser temperature probe..)

Brenner ...

Brenner

One additional comment:

The motor timing that I used for all these tests was 24 degrees, and with this timing I was pulling 100A/3500W.

One additional possibility here is that it is more than possible to use motor timing to adjust the maximum amps/power instead of ATVing the throttle back.

I am going to be experimenting with this during this week.

Brenner ...

Brenner

Here are some pictures of the installation that we are using for testing.



The installation actually looks cavernous, but available space is actually quite limited. I wouldn't be able to install a V3 Drive in here without cutting away the balsa stringers.

One thing we have recently changed is the rear support. We are now using a needle bearing that runs directly on the rotor shaft instead of a roller bearing. The needle bearing saves weight of a roller bearing, and the shaft doesn't fret.

Right now I am running it in a rubber grommet without caps, but for production we will probably cap it on both sides of the support.

Brenner ...

serious power

' Given all this, my motor case temperatures seemed to peak at about 158F (70C). Which is way under what the motor can actually handle. Kontronik claims that the magnets are good for 150C, and the wire that was used for the rewind was good for 300C, so I think we are more than good. '

Hi Brenner,
Good to hear that the testing in continuing.
Who did the rewind and do you have a spec,, for it - ball park even ??

Have you settled on a motor kv/gear ratio mix for production yet, or on whether you will be offering a range of options ?
If the weight saving (ie the extra 70g for the 600) is not required I'm thinking the standard 650 is the better option and a rewound 650 should run really really cool at the same loading.

Brian

Brenner

Hey Brian,

We are going to start production with a 7:1 gearset.Our hope is that this is the only gearset that we'll need, but we have the ability to span from 5.8:1 to 8.3:1 if we need to.

Our current thinking is that the V4 Drive should have enough additional motor choices/options to obviate the need for additional gearsets. As of now, we have tried these options:

1/.. Kontronik Pyro 650-78 Stock motor with extended shaft and additional front bearing (290g)
2/.. Kontronik Pyro 650-83 Stock motor with extended shaft and additional front bearing (290g)
3/.. Kontronik Pyro 600 Custom Rewind for 10s packs, extended shaft, and additional front bearing (220g)
4/.. Hacker Turnado A50-8s Stock motor with extended shaft (345g)
5/.. Neu 1512-3Y Stock motor (325g)
6/.. Neu 1515-2.5Y Stock Motor (380g)

All of these motors will fit in the same installation, and bolt to the same motor plate, so they are, for all intents and purposes, interchangeable.

Jason Shulman went to the Worlds in Switzerland with the Pyro 650-78, (He finished in fifth place, right behind Andrew..) (Gernot also flew a Contra drive, but his was a V3 version..) and I've been flying all summer, off and on, with the Pyro-83. Mike Gaishin has also been flying with the Neu 1515-2.5Y.

The 650 motors are way over specified for our application, and consequently they run ice-cold. The Neu 1515-2.5Y runs hot, but not excessively hot, and can be used reliably up to 40C ambient. The Neu 1512-3Y runs very hot, and requires throttle management to avoid overheating.

The Pyro 600 motor runs hotter than the Pyro 650, but not as hot as the Neu 1515-2.5Y. It's kind of like the Goldilocks of motors as far as heat rise is concerned.

The strongest motor is the Pyro-600, then the Pyro-83.

The Neu motors are inrunners, so they run with very low timing, but the rest are outrunners that run with up to 24 degrees of timing. This means that the outrunners are more flexible, because motor timing can be adjusted to dial in the power that they deliver.

Given this, I think it actually makes sense to go with the strongest, lightest, outrunner, and then adjust the motor power to suit using motor timing.

The only remaining selection criteria is cost, and since the Pyro 650 motors use their stock winding, they are going to be the cheapest. The Pyro 600 motor needs to be rewound, so this will have to more expensive. We are currently researching costs.

Brenner ...

PS-Bert Decker did the rewind...

serious power

Brenner
By Pyro 600 ,as strongest, I assume the rewound one.
What props were in use for the tests referred to above ?
I'm glad you've hooked up with Bert - I found him very helpful.

Brian

bem

My Feedback: (1)

Hi,
There is also the Pyro Competition (but no 600, start at 650):
http://www.kontronik.com/index.php?o...id=208&lang=en
Seems to be of little higher quality (if needed).

/Bo

Brenner

"Brenner
By Pyro 600 ,as strongest, I assume the rewound one.
What props were in use for the tests referred to above ?
I'm glad you've hooked up with Bert - I found him very helpful.

Brian"

Hey Brian,

I forget to mention the Props that I was using. My bad .. I used a 22x20 rear and a 22x18 front for all testing.

And yes, the only pyro 600 that I've tried is one that has been rewound for 10s by Bert.

Brenner ...

Brenner

Hey Bem,

The competition motors are of higher quality. I think they primarily use a stepped diameter shaft so that they can use larger bearings, and the main rotor casing is attached with screws rather than being pressed.

We've been working with the standard quality motors, because we have been assuming that customers will want to get the best price, and making an extended shaft that is stepped adds additional cost, above and beyond the motor cost.

Also, we are going to have to modify these motors anyway, so we will be able to make whatever changes are needed for the motors to be reliable.

Brenner ...

Brenner

A quick update:

Using motor timing to adjust motor power is a no-go. Timing doesn't seem to significantly change motor power, and if it's too low, it causes the ESC to fall out of sync.

Brenner ...

PeterP

Hi Brenner,

Great work look forward to the release of the V4 drive. Quick question I am about to commence assembly of a new model and I am trying to decide on the best motor mounting arrangement which will allow me to interchange btw the V3 drive and the V4. I would like to avoid making any structural modifications to install the V4 if possible when it becomes available.

Brenner

Hey Peter,

If you install your V3 Drive with a Neu f3a motor, and with the motor plate in front of the fuselage plate, you should be able to install a V4 Drive without having to modify your installation.

We are going to supply the motor with about 5mm of extra front shaft length so that the customer can use a Dremel cutoff wheel to adjust the location of the Drive with respect to the nose of the plane. This extra 5mm should locate your V4 Drive with a 3mm gap between the rear spinner and the nose of the plane.

In actual fact, the V4 will simplify most installations significantly because the axial location of the Drive on the motor shaft is adjustable, and the axial location of the rear support is also adjustable. In addition, all motors will be able to use a common motor mount plate and common motor mount datum.

We are expecting that most people who are currently using a V3 Drive will be able to drop in a V4 Drive without having to redo their installation.

Brenner ...

az

Dear Brenner,
when you can start to supply new version V4?
Im interesting in version with Kontronik Pyro 650-78.

I expect motor will be part of delivery, or?

Please let me know.


Ales

Brenner

Hey Ales,

Our current plan is to be able to start supplying V4 Drives sometime towards the end of November, and mo later than the end of the year. The motor will be included with the drive, as will the rubber mounts, and the mounting plates.

It will be easier for us to get either the Kontronik Pyro 650-78, or the Pyro-83 motors, so these will be offered as standard. The Pyro 600 motor has to be custom rewound, so this will be difficult for us to get.

Brenner ...

OhD

Am I the only one that has trouble pulling the front spinner? I built my own puller for my original Contra but it doesn't work on the newer one with all the lightening holes. The brass unit supplied has worked until now but I need to put a lot of torque on it and I can't keep the spinner from turning. Is there a secret? How do you all hold the spinner when turning the puller?

Jim O

Jason Arnold

Hi Jim,

I assume you mean the middle spinner. My one comes off easily by holding the spinner and screwing the brass puller in by hand. Perhaps check to see if the tapered collet is damaged in any way?

Cheers,
Jason.

Stuart Chale

Mine as well. Never even had to put a wrench on the brass puller.

OhD

I must have over torqued the nut on the front prop. Time to design a new tool I guess. A miniature wheel puller?

Jim O

serious power

Hi Jim,
I clean the edges on the slot cut and never need the brass tool.
Might be worth polishing the mating surfaces a little.
Also I always check for squareness as I tighten the front prop by checking the gap while turning the front prop.

If it is stuck as we speak ; Put a ring spanner on the brass 'pusher' tool. Hold/grip the middle spinner in a paper towel and tap/hit the spanner sweetly to loosen/break the lock. Use a pin hammer or something with some weight but light enough to swing sweetly.

Brian