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Contra Rotating Propeller Drive for f3a 2m Pattern Planes

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Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Old 04-16-2015, 10:39 AM
  #1451  
Dean Pappas
 
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Hi Brenner,
I was certain that you'd thought it through!
So you are somehow clamping to the motor's output shaft?
Many moons ago I noticed how much heat my wet engines lost through the spinner ... never figured out why some guys ran plastic.
I look forward to seeing pictures and drawings.
take care,
Dean
Old 04-16-2015, 11:27 AM
  #1452  
Brenner
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Hey Dean,

Should be a cross section view in a previous post ...

Brenner
Old 04-16-2015, 05:24 PM
  #1453  
Dean Pappas
 
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Hi again, Brenner.
I found that section, and WOW ... there is no question in my mind that you made quite an improvement in bearing and gear life with the improvement in stiffness of the system.
Grabbing the tail-shaft with a bearing does wonders too, I'll bet.

In CL Stunt, where guys were mangling bearings on rear-mounted outrunners in maybe 100 flights, turning them around and mounting at the front made almost everybody's problems go away.
The problems that were left, almost all of which signaled their presence with funny noises in the 1/4 second long 1/4 loops, were due to flexibility and resonances in the fuselage.
The tail-shaft bearing killed those, though most guys don't need it now that we understand how to build stiff noses and use 0.093" G-10 for the motor mount former rather than mere plywood.

again, Bravo
Dean
Old 04-16-2015, 05:31 PM
  #1454  
Brenner
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Hey Dean,

Thanks for sharing info from the CL world. I find that it helps tremendously to find out what people are doing to solve similar problems in other areas.

Brenner ...
Old 04-19-2015, 09:14 AM
  #1455  
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I spent yesterday switching props, and I think the 22x20R / 22x18F combination works very well with the Kontronik motor and the V4 Drive.

The Kontronik motor seems to add a lot of speed range, which makes these props much more useable in windy conditions.

According to my ESC log I am pulling a maximum of 87A with these props, and and I'm using about 3000mah for the new AMA Masters pattern, which should be comparable to P15.

See attached for a screenshot of the throttle curve that I'm now using. This curve gives me a very linear response from the Drive. Right now I don't know if the uptick off idle is actually needed, With my V3 Drive, this uptick was about twice as much, and I just kept reducing it until I was happy with the throttle response during stall turns.

Brenner ...

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Old 05-19-2015, 12:16 PM
  #1456  
villalbi2003
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HI Brenner
what do you think about the new hacker motor in develop specially for contradrive, C54L 4 pole more couple less consuption and low heat and 70 gram less as weight!
link: http://shop.lindinger.at/product_inf...cts_id=9716303
Of course will be necessary differet gear ratio for example 1:6.5,do you think will be avaible for V3 contradrive ?
Do you think will be a new chance for V3 contradrive(for v4 i think there may be problem for pignon conection)
Alberto
Old 05-21-2015, 04:30 AM
  #1457  
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Hey Alberto,

Yes, we could develop a gearset to use this motor, but currently we think it will be better to develop motor options for our new V4 Drive.

For people who have a preference for Hacker motors, we are going to try one of Hacker's Turnado helicopter motors. These motors weight 345g, so there is a weight savings over the Hacker C50 motor, and I think this weight is going to comparable with the Hacker C54. Also, there is an added benefit in that the Turnado motor is cheaper as well.

We are also working on options that use a Plettenberg motor, and a Neu motor too. Both of which should be as light, or lighter.

Brenner ...
Old 05-21-2015, 01:25 PM
  #1458  
Jason Arnold
 
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Originally Posted by Brenner
Hey Alberto,

Yes, we could develop a gearset to use this motor, but currently we think it will be better to develop motor options for our new V4 Drive.

For people who have a preference for Hacker motors, we are going to try one of Hacker's Turnado helicopter motors. These motors weight 345g, so there is a weight savings over the Hacker C50 motor, and I think this weight is going to comparable with the Hacker C54. Also, there is an added benefit in that the Turnado motor is cheaper as well.

We are also working on options that use a Plettenberg motor, and a Neu motor too. Both of which should be as light, or lighter.

Brenner ...
Hey Brenner,

Does the new Plettenberg motor that Chad is testing on the V3 require a special manifold adaptor?

I have to say that my contra is going just awesome. The combination of your CRS, Ralph Schweizer's soft mount and Bryan Hebert's new Allure is absolutely awesome. A number of people have now flown my Allure and they are just blown away by the complete package. This airframe has caught up to your technology and IMHO CRS will be the way of the future in F3A.

Cheers,
Jason.
Old 05-21-2015, 02:08 PM
  #1459  
Brenner
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Hey Jason,

I'm glad to hear that your Allure is flying so well. I definitely agree that it's an excellent airframe.

The motor that Chad is testing does require an adapter, but that's because it's using an off the shelf motor rotor, so it's necessary to space the motor back from the gearcase to make the extended shaft length correct.

Chad is working with Plettenberg to get the right winding, and the right cooling, etc.

Brenner ...
Old 05-21-2015, 08:55 PM
  #1460  
OhD
 
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Brenner, any comments on the concepts using what looks like helicopter variable pitch props to control the thrust vector? Seems like the next step. If pattern doesn't start embracing new technologies it is going to become irrelevant, if it wants to claim to have the best flying model airplanes. My opinion.

Jim O
Old 05-22-2015, 01:54 AM
  #1461  
Dansy
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Brenner you have a time line for the V4 yet?

Variable Pitch has been used before with little success, wouldn't an Auto variable pitch be against the current rules???
Old 05-22-2015, 05:00 AM
  #1462  
Brenner
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Hey Jim,

I think it could be done.

What would you do during a sound test though? Would you be required to cycle the pitch throughout the range so that the sound meter could pick up the maximum sound, or could you set the pitch at its quietest setting?

Brenner ...
Old 05-25-2015, 05:54 AM
  #1463  
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My flying buddy is experiencing loss of power in his contra which he has interpreted as clutch slippage. I remember someone ( Malcolm, I think) describing two identical units/aircraft, yet one clearly had more power. Any thoughts...recomendations ?
Old 05-25-2015, 07:01 AM
  #1464  
Brenner
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Hey Preston,

If the clutch is slipping we have an upgraded ring gear and clutch plate that will solve this problem.

The clutch plate has an array of slots cut into its outer edge, and then tabs at the edge are bent up at a slight angle. These tabs then engage with shallow notches that are cut into the underside of the ring gear. This couples the two parts together, preventing any slippage.

Tell your buddy to send me an email. and we can send him upgraded parts.

Brenner ...

Last edited by Brenner; 05-25-2015 at 07:39 AM.
Old 05-25-2015, 08:05 AM
  #1465  
Brenner
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A quick update on Contra V4 development.

We have been able to try several motors with different winds, and three different gear ratios, and based on this testing, it looks like the 6.75:1 gear ratio is the best allaround ratio.

This ratio lets us use either the Kontronik Pyro-78, or the Pyro-83 motors interchangeably. The Pyro-78 pulls about the same as a V3 Drive with a Neu f3a motor, whereas the Pyro-83 is stronger. I'm running a Pyro-83 motor right now with the throttle ATV'd back to 70%, and at this setting I can fly pretty much any pattern I want.

This gear ratio also lets us use the Neu 1515/2.5Y, or the 1515/3Y motors. Mike is currently running the 1515/2.5Y in his setup, and it's working great for him. In addition, this gear ratio should also work very well with the Hacker Turnado A50-8S, and the Plettenberg Orbit 30-10. These motors are going to be tested next.

I've attached some pictures that show how the V4 is installed in my current plane. This plane has very little room for an installation. My V3 Drive actually wouldn't fit in this space, but the V4 fits just fine. I think the V4 Drive actually takes up less space than an equivalent single prop inrunner setup, and definitely less space than any outrunner setup.

The Drive in this particular installation has been shimmed back about 3mm to match the spinner with the front of the fuselage. (shims are visible as end grain balsa behind Budd Mounts..) I used shims because I didn't want to cut the motor rotor shaft to length until I finish all of my motor testing. When this testing is complete, I will cut 3mm from the shaft and remove the shims.

One of the things that we've been working on is grease retention. We want to have a Drive that doesn't leak grease all over the inside of the plane, which can be a problem with gearbox inrunner systems.

The Drive in the picture was taken after about twenty flights, and was not cleaned in any way. There are some specs of grease on the walls of the fuselage, but they are from when I first ran the V4 in this plane. Since then we have cut a set of grease return channels that allow any grease that migrates through the main bearings to return to the grease reservoir inside the Drive instead of spilling out the back, and onto the plane.

What we need to do now is see how long the Drive needs to go before it needs regreasing. We are hoping for considerably more flights than with the V3, but this is something that we have to test for before we can make any claims.

Brenner ...

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Old 06-14-2015, 10:42 AM
  #1466  
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Hi,
At this weekend's W Cup event in Austria the top 5 were all using contras !! Must be a first.

Brian
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Old 06-14-2015, 05:24 PM
  #1467  
Brenner
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Hey Brian,

What's the new plane that Gernot is flying?

Brenner ...
Old 06-14-2015, 05:48 PM
  #1468  
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It is his older Sensation design, with new wings. It's ultra light. I think he runs 8's.
Old 06-14-2015, 07:01 PM
  #1469  
Brenner
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Interesting...

Our new V4 Drive with a 220g Kontronik pyro motor and 8s packs could potentially work well for Gernot and this plane.

With this setup, he'd save 260g over an equivalent V3 setup, not including the 220g or so savings with the 8spacks. The complete Drive setup with spinners and props would weigh about 550g. Also, it would deliver 2kW continuous, and 3kW intermittent.

I wonder if the lower weight would more than offset the disadvantage of using 8s packs.

Brenner ...
Old 06-14-2015, 08:44 PM
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I read somewhere he is around 4,400 grams which is nuts.
Old 06-14-2015, 11:02 PM
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Hi Brenner,
Yes a Sensation with new wings and tail.
The old one had small wings and this appears to have some extra area and quite a bit more span. The tail looks bigger also.

At the minute he seems to be using the adverrun.
With 8s you are carrying less fuel load.
A lighter model will need less as the work in the verticals is a straight pro-rata reduction and the induced drag is also reduced which is significant from a power req'd point of view.
So I would think it would be close to a trade off (assuming the model is 12+% lighter before the motor and battery weight savings).

Last year Gernot was the most extreme exponent of the slooow and close in flying style. This set up appears designed to enhance that further.
I would speculate that his mA usage was around 2500 or less for a P last year (in calm weather)
I would not be able to do that as the difficulty level is very high.

Brian
Old 06-15-2015, 06:50 AM
  #1472  
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Hi Brian and Brenner,

According to one of the pictures and comments Gernot had up on his Facebook page he states that with the new Wings and Tail the model weighed less then 4kg.

Interesting wing design as the characteristic shape followed the same outline as his Trivia 2.0 F3P model. Same color scheme too.

Mikey
Old 06-15-2015, 06:54 AM
  #1473  
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Old 06-15-2015, 07:23 AM
  #1474  
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I think you are right about the 4,000 grams. That's even more "crazy". The scheme he is using started with the Evolaris he flew last year. The Evolaris was all painted, but I would have to assume his new Sensation is film covered. The wing design is pretty simple compared to his Evolaris.
Old 06-16-2015, 09:26 AM
  #1475  
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The motor alternatives for Hacker or Neu

Plettenberg. Nice vid form Chat:
https://www.youtube.com/watch?v=T3uu8Ac5b2Y



And the Leo

http://www.ralphschweizer.com/startseite.htm

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