Go Back  RCU Forums > Electric Aircraft Universe > Electric Pattern Aircraft
Reload this Page >

Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Notices
Electric Pattern Aircraft Discuss epowered pattern aircraft in this forum

Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Old 04-06-2015, 10:27 PM
  #1426  
Jason Arnold
 
Jason Arnold's Avatar
 
Join Date: Aug 2005
Location: Sydney, AUSTRALIA
Posts: 1,341
Likes: 0
Received 0 Likes on 0 Posts
Default

Hi Guys,

Is anyone able to advise the base ESC settings for a NEU F3A(Contra) motor with a Jeti Spin99 Pro?
I think it's two poles but unsure on the timing.

Cheers,
Jason.
Old 04-07-2015, 03:21 AM
  #1427  
Brenner
Thread Starter
 
Join Date: Jul 2007
Location: Bridgman, MI
Posts: 793
Received 9 Likes on 9 Posts
Default

Hey Jason,

I've been running my Neu motors at 0 degrees, 8 khz, and setting the number of poles at 4.

Brenner ...
Old 04-07-2015, 03:37 AM
  #1428  
Jason Arnold
 
Jason Arnold's Avatar
 
Join Date: Aug 2005
Location: Sydney, AUSTRALIA
Posts: 1,341
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by Brenner
Hey Jason,

I've been running my Neu motors at 0 degrees, 8 khz, and setting the number of poles at 4.

Brenner ...
Thanks Brenner,

That'll get me going.

Cheers,
Jason.
Old 04-07-2015, 03:37 AM
  #1429  
Brenner
Thread Starter
 
Join Date: Jul 2007
Location: Bridgman, MI
Posts: 793
Received 9 Likes on 9 Posts
Default

I have been asked me to clarify the 640g all up weight claim that I made previously.

640g all up includes the Drive, a modified Kontronik 650 Pyro motor, (extended shaft and extra front bearing...) the rear support, front and rear spinners, and front and rear props with prop nuts.

It doesn't include carbon fiber plates, (fuselage plate and motor plate) or the Budd rubber mounts.

We are also looking at the Kontronik 600 Pyro motor, which would save an additional 70g, but it's only rated for an 8s pack, so we aren't holding our breath.

Brenner ...
Old 04-07-2015, 07:53 AM
  #1430  
Stuart Chale
 
Join Date: Jul 2005
Location: , NY
Posts: 662
Likes: 0
Received 8 Likes on 6 Posts
Default

There has to be a story behind the melted case on the Watt meter in the recent pictures
Old 04-07-2015, 08:13 AM
  #1431  
Brenner
Thread Starter
 
Join Date: Jul 2007
Location: Bridgman, MI
Posts: 793
Received 9 Likes on 9 Posts
Default

Yes there is...

I had a spontaneous Lipo fire in my tool box on the way home from the field. I was about five minutes from home when I started smelling a pungent burning smell. I naturally assumed that I was passing through a neighborhood where someone was torching a car or something. It happens a lot in Michigan.

However, I got suspicious when I pulled in to my Driveway and the smell was stronger. My house looked ok, and I couldn't see any visible flames in the neighborhood, so I started unloading my plane, and it was then that I realized that I had been driving with a lipo fire in my tool box. Apparently, one of my RX lipos has spontaneously combusted, burning and melting anything that was close to it.

Lucky for me it burned itself out without melting through the side of the box, so my car was undamaged, but I definitely lost most of the stuff inside. I was also left with a distinct fear/phobia concerning the safety of Lipos. The battery in question hadn't been shorted out, and it hadn't been over discharged, or overcharged. It also hadn't been used for several months either.

My Wattmeter was partially melted, but still functional, but I'm going to replace it anyway. That is, as soon as I can remember to replace it.

Brenner ...
Old 04-07-2015, 12:52 PM
  #1432  
Jason Arnold
 
Jason Arnold's Avatar
 
Join Date: Aug 2005
Location: Sydney, AUSTRALIA
Posts: 1,341
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by Brenner
Yes there is...

I had a spontaneous Lipo fire in my tool box on the way home from the field. I was about five minutes from home when I started smelling a pungent burning smell. I naturally assumed that I was passing through a neighborhood where someone was torching a car or something. It happens a lot in Michigan.

However, I got suspicious when I pulled in to my Driveway and the smell was stronger. My house looked ok, and I couldn't see any visible flames in the neighborhood, so I started unloading my plane, and it was then that I realized that I had been driving with a lipo fire in my tool box. Apparently, one of my RX lipos has spontaneously combusted, burning and melting anything that was close to it.

Lucky for me it burned itself out without melting through the side of the box, so my car was undamaged, but I definitely lost most of the stuff inside. I was also left with a distinct fear/phobia concerning the safety of Lipos. The battery in question hadn't been shorted out, and it hadn't been over discharged, or overcharged. It also hadn't been used for several months either.

My Wattmeter was partially melted, but still functional, but I'm going to replace it anyway. That is, as soon as I can remember to replace it.

Brenner ...
The worst thing would be getting that smell out of the car...

Michigan sounds like a nice neighbourhood Brenner. ;-)

Cheers,
Jason.
Old 04-07-2015, 01:41 PM
  #1433  
Stuart Chale
 
Join Date: Jul 2005
Location: , NY
Posts: 662
Likes: 0
Received 8 Likes on 6 Posts
Default

Originally Posted by Brenner
Yes there is...

I had a spontaneous Lipo fire in my tool box on the way home from the field. I was about five minutes from home when I started smelling a pungent burning smell. I naturally assumed that I was passing through a neighborhood where someone was torching a car or something. It happens a lot in Michigan.

However, I got suspicious when I pulled in to my Driveway and the smell was stronger. My house looked ok, and I couldn't see any visible flames in the neighborhood, so I started unloading my plane, and it was then that I realized that I had been driving with a lipo fire in my tool box. Apparently, one of my RX lipos has spontaneously combusted, burning and melting anything that was close to it.

Lucky for me it burned itself out without melting through the side of the box, so my car was undamaged, but I definitely lost most of the stuff inside. I was also left with a distinct fear/phobia concerning the safety of Lipos. The battery in question hadn't been shorted out, and it hadn't been over discharged, or overcharged. It also hadn't been used for several months either.

My Wattmeter was partially melted, but still functional, but I'm going to replace it anyway. That is, as soon as I can remember to replace it.

Brenner ...
A better story than expected

Stuart
Old 04-08-2015, 03:15 AM
  #1434  
serious power
 
Join Date: Nov 2007
Location: wexford, IRELAND
Posts: 1,119
Likes: 0
Received 1 Like on 1 Post
Default

Hi Brenner,
I have made contact with a well regarded re-winder guy in Europe.
He can get a Pyro 650 with a YY wind at 1010rpm/V and or 1120rpm/V and at 3.5kW to 3.75kW continuous load.
That 1120 version with your 8.4:1 ratio should suit Dave L
He can also do a 600 which would mean it could take 10S alright.
He has not done a Pyro 600 so can only speculate at power but it looks like up to 3kW is possible - we (the collective we)would likely be pushing this some at times, but a further 25 to 30g saving is possible.
A 650, rewound so, would run very cool with say a 2kW to 2.5kW flight load.

Cost for a one off is approx €115 inc shipping.
However, maybe, Kontronik might co-operate to facilitate a 'Contra Special'. So maybe €50 to €60 above std,, is possible - in due course.
Worth bearing in mind as you get your current testing complete.

What range of gear ratios are possible with the V4 - I'm asking in the context of motor rpm/V's !??

The weights you are quoting are very special indeed.
Hope the testing goes well.

Brian

Last edited by serious power; 04-08-2015 at 03:17 AM.
Old 04-08-2015, 05:15 AM
  #1435  
Brenner
Thread Starter
 
Join Date: Jul 2007
Location: Bridgman, MI
Posts: 793
Received 9 Likes on 9 Posts
Default

Hey Brian,

This is very useful information. Thanks for doing this research. Can you give me this guy's contact info?

A Pyro 600 that runs on 10s, and is rated for 3kW, would be the ultimate Contra motor. A motor like this would make Contra Drives fundamentally lighter than all currently available single prop systems. Of course, there is nothing that prevents developers of single prop systems from pursuing a similar approach.

Within the same gearcase housing, and using the same ring gear, we can create gear ratios from 5.8:1 to 8.3:1.

What we have done is shift the design inference space to lower gear ratios, which allows us to correspondingly scale the size and weight of the gearbox. However, doing this requires motors that have higher torque, so there is a trade-off between gearbox size/weight, and motor size/weight. What we're trying to do is hit the sweet spot between these two trade-offs.

Brenner ...

Last edited by Brenner; 04-08-2015 at 03:58 PM.
Old 04-08-2015, 05:30 AM
  #1436  
serious power
 
Join Date: Nov 2007
Location: wexford, IRELAND
Posts: 1,119
Likes: 0
Received 1 Like on 1 Post
Default

Brenner,
I'll drop him a courtesy line and revert - by email !

Brian
Old 04-08-2015, 01:39 PM
  #1437  
PeterP
 
Join Date: Feb 2003
Location: Brisbane, AUSTRALIA
Posts: 493
Likes: 0
Received 1 Like on 1 Post
Default

Can someone tell me what the upper operating temperature limits are for the Neu 1513/Y (currently used with the Brenner Contra Drive)
Old 04-08-2015, 04:03 PM
  #1438  
Brenner
Thread Starter
 
Join Date: Jul 2007
Location: Bridgman, MI
Posts: 793
Received 9 Likes on 9 Posts
Default

Hey Peter,

It's been my understanding that you don't want to see motor case temperatures much above 80C, but the Neu 1513/Y is a motor that usually runs quite cool, and if you're seeing anything much above 60C on a hot summer day, you might have demagnetized the rotor, and are drawing too much current. This will also fry your ESC as well.

Brenner ...
Old 04-08-2015, 05:07 PM
  #1439  
PeterP
 
Join Date: Feb 2003
Location: Brisbane, AUSTRALIA
Posts: 493
Likes: 0
Received 1 Like on 1 Post
Default

Thanks Brenner,

I am measuring 69C - 70C after landing with a temp gun on the rear of the motor. I assume the temp will rise slightly after landing because the fan is not running and there is no forced airflow over the motor.

In order to reduce these temperatures should I try and direct air over the rear of the motor or near the fan. Is there any way of testing the motor to determine if there is any damage. Last time I checked I was pulling 80-85 Amps static with 22x22R 22x20F 10.15 gearing.
Old 04-08-2015, 05:36 PM
  #1440  
Brenner
Thread Starter
 
Join Date: Jul 2007
Location: Bridgman, MI
Posts: 793
Received 9 Likes on 9 Posts
Default

Hey Peter,

85A is still very reasonable with the 1513 motor, so I don't think your motor is damaged. I demagnetized a Hacker C50 once, and the motor current went up to about 110A.

I think what's more likely is you don't have enough airflow over the top of the motor. What I have found is that it helps a lot to open up some air holes in the nose of the plane, on top, just behind the spinner. This lets air in directly over the top of the motor where it is most stagnant.

The Sebart Wind S Pro comes from the factory this way, and my motors always run much cooler in this plane.

Unfortunately, the only way that I know of testing rotor magnets is to compare the magnet pull force to a rotor that I know is good. What I do is place each magnet on top of a digital scale that has a metal pan, and then I measure the force required to pull each rotor free from the scale. If the pull force is the same for both rotors, then they are both good.

Brenner ...
Old 04-08-2015, 10:09 PM
  #1441  
serious power
 
Join Date: Nov 2007
Location: wexford, IRELAND
Posts: 1,119
Likes: 0
Received 1 Like on 1 Post
Default

Hi Peter,
The fan on that Neu is at the front and it is centrifuging out air at the front.
Unfortunately, therefore, the airflow through the motor is rear to front.
We 'duct' the chin intake air directly to the rear of the motor. This duct works best if it by-passes the front of the motor with the incoming air. We also block of any cheek intake near the front - or duct this to the rear also/instead.
We just block this off.
The idea is to create a +ve pressure differential rear to front with the cool incoming air. This will allow the motor to pump cool through itself.
Our motors are at 40* to 50*/

Brian

Last edited by serious power; 04-08-2015 at 10:21 PM.
Old 04-09-2015, 03:48 AM
  #1442  
PeterP
 
Join Date: Feb 2003
Location: Brisbane, AUSTRALIA
Posts: 493
Likes: 0
Received 1 Like on 1 Post
Default

Hi Brian / Brenner

Thanks for the advice. I made some changes to my model (prior to seeing Brian's post) by adding baffles which direct fresh air through the cheeks onto the the motor case. I am using the Hyde mount which sort of obstructs the airflow from the fan due to its design so I wasn't sure if that was a contributing factor to the high temps I was seeing. Anyway I had 6 flights this evening and the difference to cooling is significant. My motor temperatures have dropped by almost 20C with just the inclusion of baffles. I am quite surprised they have made that much difference. The temp gun and my eagle tree logger both read 45-48C approx 110F so I am confident the results are genuine.

I have also had a chance to install the throttle tech device (a week ago) into my model and I must say it is a great addition to my setup. My throttle management skills are not as good as they should be so I have found this device to be a welcome relief. The biggest benefit I have noticed is my packs (old and new) all feel the same throttle response wise. I prefer to use a slightly higher C rating on batteries as they don't get abused as much as the 25C batteries. The only issue I had with the high C rated batteries was the ON - OFF throttle response. The throttle tech has tamed them down so they feel like my 25C batteries. Currently using 35 as a compensation factor with Spin-99 ESC. My power consumption has dropped btw 5~10% per flight as a result of adding the TT.
Old 04-09-2015, 06:13 AM
  #1443  
Brenner
Thread Starter
 
Join Date: Jul 2007
Location: Bridgman, MI
Posts: 793
Received 9 Likes on 9 Posts
Default

Hey Peter,

I'm glad your motor heat rise problem is solved. I think a lot of motor heat rise problems can be traced to a general lack of airflow over the motor case.

In our V4 Contra design we are trying to mitigate this problem in a number of ways:

1/.. We have air vent slots in the base of the rear hub that allow cool air to flow through the spinner and into the nose of the plane.
2/.. The gearcase has a considerably smaller diameter, and is coned at the rear to give air flow a direct path to the motor case.
3/.. We are going to put vent holes in the front motor plate to do the same.

Our hope is that with these changes heat rise won't be a problem with any properly designed motor.

Brenner ...
Old 04-13-2015, 11:08 AM
  #1444  
Brenner
Thread Starter
 
Join Date: Jul 2007
Location: Bridgman, MI
Posts: 793
Received 9 Likes on 9 Posts
Default

The weather in Michigan is finally giving us some actual flying weather, (13C over the weekend..) and Mike and I are taking advantage of our good fortune to get serious about testing our V4 Contra Drive prototypes.

We are running two setups. Mike is running a 6.75:1 gearset with a 1515/2.5Y Neu motor, and I am running an 8.3:1 gearset with a Kontronik Pyro 650-103 motor.

The Contra Drive itself is about 70g lighter than the V3 Drive. The Neu motor weighs 390g, and the Kontronik motor weighs 295g.

This results in a 60g saving for the Neu setup, and a 155g saving for the Kontronik setup.

The Neu setup has performance that is very similar to a comparably equipped V3 Neu motor based setup. Heat rise is also very acceptable.

The Kontronik setup has more performance. With this setup, and 22” props, I am pulling 100A max. The props are spinning at 4500 rpm, and I am drawing about 3500W from my packs. These are maximum values from my ESC log. With 20” props I am drawing close to 90A, and pulling about 3300W from my packs. Heat rise is also minimal. I am using a 130A Mezon controller, and it is running very cool. The motor itself is barely warm to the touch.

One thing that is interesting is that the spinner is actually warmer to the touch than the motor. I am ascribing this to the fact that the Drive is clamped solidly to the motor rotor shaft, and since the winding gets hotter than the motor case, the heat from the winding is conducting along the rotor shaft into the aluminum Drive., which means that the Contra Drive is essentially acting as a big heat sink, and keeping the motor winding cool.

One other thing that I noticed is that the Kontronik setup seems to be a lot more responsive at low rpm. There is no perceivable lag when the throttle is advance, and it seems to gain rpm more quickly. I am speculating that this is because the motor itself has more torque, and the gear ratio is also lower, which accelerates the props faster.

Another noticeable effect is that the throttle response in the mid range seems to be noticeably more linear than then with the V3. A click of throttle results in a predictable increase in power and speed, and this response seems to be the same over the full mid range of the motor. This required me to change my throttle curve from a non linear curve to a straight linear curve.

Mike Gaishin has built a new version of his Integer pattern plane over the winter, (See picture ...) and with his V4 setup, his all up weight is 4600g, which is good news for me, because Mike also built one for me as well, and my expectation is that my setup, with 5100mah packs, is going to get very close to a 4500g all up weight, which leaves 500g margin for me to consider using a 6500mah pack, which should be an excellent match for a Contra Drive that is pulling close to 3500W.

One final observation, the reduced weight required me to move my battery packs forward by about 6”. (See picture ...) Fortunately however, my battery tray was just long enough to accommodate this.

Brenner …


Attached Thumbnails Click image for larger version

Name:	IMAG00078.jpg
Views:	1067
Size:	2.08 MB
ID:	2088697   Click image for larger version

Name:	IMAG00088.jpg
Views:	1036
Size:	2.18 MB
ID:	2088698  

Last edited by Brenner; 04-13-2015 at 01:18 PM.
Old 04-14-2015, 02:07 PM
  #1445  
OhD
 
Join Date: Oct 2002
Location: west hills, CA
Posts: 1,160
Received 8 Likes on 5 Posts
Default

A rare engineering achievement. Everything is going in the right direction. Congratulations!

Jim O
Old 04-14-2015, 04:28 PM
  #1446  
Brenner
Thread Starter
 
Join Date: Jul 2007
Location: Bridgman, MI
Posts: 793
Received 9 Likes on 9 Posts
Default

Hey Jim,

Thanks for the good wishes.

I must admit that flying the Kontronik powered V4 Drive is really addictive. It really winds up in the air, It's like listening to a high revving V12 powered sports car wind up on the back straight at a race track. I'm probably going to have to set up multiple rates for my throttle.

Brenner ...
Old 04-15-2015, 09:42 AM
  #1447  
Anthony-RCU
My Feedback: (2)
 
Anthony-RCU's Avatar
 
Join Date: Jan 2002
Location: Ossining, NY
Posts: 630
Likes: 0
Received 0 Likes on 0 Posts
Default

Brenner, this is a great update to a really good product. Glad to see parallel development of an off the shelf motor option. Anxiously awaiting commercialization!
Old 04-15-2015, 10:21 AM
  #1448  
Brenner
Thread Starter
 
Join Date: Jul 2007
Location: Bridgman, MI
Posts: 793
Received 9 Likes on 9 Posts
Default

Hey Anthony,

Thanks for the kind words. We plan on bring the V4 Drive to market as quickly as possible. However, we definitely need to take the time to verify and validate durability and reliability.

Brenner ...
Old 04-16-2015, 07:50 AM
  #1449  
Dean Pappas
 
Join Date: Jan 2004
Location: South Plainfield, NJ
Posts: 338
Likes: 0
Received 0 Likes on 0 Posts
Default

Hi Brenner,
The prospect of a 5 ounce weight savings with the Kontronic motor is astounding.
Can I assume that you've discussed this application with Herr Konrath?
Maybe the RPM rating for the motor is wildly conservative, but with the 1030 Kv, you are turning upwards of 35,000 RPM against the 25,000 rating.
I'm betting you've provided for this with your additional bearing and whatever support the rigid connection to the shaft provides.
If it doesn't involve spilling the secret sauce, what gives?
again ... Bravo
Dean Pappas
Old 04-16-2015, 10:05 AM
  #1450  
Brenner
Thread Starter
 
Join Date: Jul 2007
Location: Bridgman, MI
Posts: 793
Received 9 Likes on 9 Posts
Default

Hey Dean,

I haven't spoken to Herr Konrath, (that I know of..) but I have asked Kontronik product support about running faster than 25,000 rpm. They say that it can be done, and the 25,000 limit is conservative.

In addition, we are adding two extra bearings, a front bearing to take the axial loads, and a rear bearing for rear support, and to support any fore/aft bending moments. These two bearings will remove a lot of the load from the existing bearings. Also, the existing bearings are sized to support radial loads from belts, gears, and pulleys, which don't exist in this application.

So, if you assume that the original bearings were sized for radial loads and bending moments from belts, gear and pulleys at a max rpm of 25,000 rpm, The calculated life without these loads, is actually considerably more, even at 35,000 rpm plus. Also, the bearing sizes used in the Drive are good for 35,000 rpm to 45,000 rpm plus, so I think we're good.

Brenner ...

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.