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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 11-23-2010, 12:00 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

We will follow up our first batch as quickly as we can with our second batch.

My expectation is that drives from our second batch will become available sometime in April. The reason we want to do it this way is because we are revising the design from what we tested and flew last summer so we want to build a small batch of drives first and make sure that the technology is right before we have the confidence to go with larger quantities.
Old 11-23-2010, 12:01 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Here are some screenshots of our version 2 drive CAD model. The CAD system is Pro-Engineer.
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Old 12-23-2010, 10:07 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Looking forward to test this system
Old 12-23-2010, 10:23 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Right now is an exciting time for us, because we are starting to see actual parts come in and we can hold them in our hands and feel them. Last week Mike and Andy finished the drive shaft/carrier assembly, and it was light as a feather, due in large part to the through hole we put in it. They also made all of the pinion and planet gears. They had me running a machining center for five hours cutting out all the planets. I think they wanted me to "feel the pain", considering how many different gear sets I specified.

They made housings over the weekend, and I had a chance to see them on Monday. They look like little works of art, and they seemed so light I was almost afraid to breathe too hard in case they floated away. (a slight exageration, but still...) The spinner and hubs are next, but Andy says that the housing was the hardest part, so he thinks it's going to be easier from here on.

Mike has the props nailed too. They are looking as good as the carbon fiber props that Andrew runs on his Spark, and he's been able to take a lot of weight out. Right now he's coming in at 65 to 70 grams per prop. Fortunately however, he hasn't sacrificed stiffness or strength, because the hub and the first 25% of the blade sections are still solid resin and carbon fiber tow. It looks like both props are going to weigh about the same as a single 22 inch APC prop.

Brenner ...
Old 01-07-2011, 04:43 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Here are some pictures of the parts that are coming in.
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Old 01-08-2011, 03:29 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Could you show the process of full assembly of this drive?

It looks just awesome- I would like one on the shelf just to look at
Old 01-08-2011, 06:37 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Sure, I'll try and explain as best as I can.

The gearcase housing, which is shown in the second picture on the top row, has a bearing pressed into the the large open diameter that's shown in the picture. The ID of this bearing is connected to an adapter manifold that bolts to the motor, which can either be a Neu f3a motor, or a Hacker C50 Competitiion motor. The gears, shown in the third picture on the bottom row, fit into the bottom side of the gearcase housing, which is then bolted to the rear hub part shown in the first picture in the top row.

The drive shaft passes through the center of the rear hub, and is supported by ball bearings. The rear hub assembly is bolted to the gearcase housing, and forms the base of the spinner.

The rear prop fits over the center section of the rear hub, (shown in the last picture on the bottom row ...) and is bolted on with the bottom spinner section (third picture, top row ...) using a large aluminum nut, (not shown ...) Then a front hub is added, and the front prop is bolted onto the drive shaft with another aluminum nut, and the front spinner is installed to complete the assembly.

When the uniit runs the motor drives the pinion gear, which then applies equal but opposite driving torques on the gearcase housing and the driveshaft. This causes the two props to spin in opposite directions.
Old 01-18-2011, 05:56 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Here are some pictures of the first version 2 Contra Drive that we have assembled. The motor shown is the Neu f3a motor. This Drive hasn't been anodized yet so what's shown are the natural aluminum machined surfaces.
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Old 01-21-2011, 11:46 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

It looks great, now we just need to shorten the length down with 35 mm
Old 01-21-2011, 12:00 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Good idea!

We can look into doing that next. We would have to run teeny tiny props though ...
Old 01-27-2011, 05:11 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Mike has figured out how to make props that are light, stiff, and strong. This is a picture of his latest prop. With a pair of these props the weight of the drive drops to about 785g. Time to shoot the engineer I think ....
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Old 01-27-2011, 09:30 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Beautiful work Brenner.. really impressive stuff!
Old 02-03-2011, 08:16 PM
  #113  
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Here are some pictures showing what the Drives look like after they've been anodized.
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Old 02-06-2011, 05:50 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Does a drive include a gear set?
Old 02-06-2011, 06:01 AM
  #115  
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Sure, absolutely... There are four gear ratios to choose from.
Old 02-09-2011, 09:16 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Hi guys, Brenner has started to ship the contra drive units and mine just arrived today and it looks awesome. Everything is nicely boxed up in a small package and they thought of everything from the carbon mounting plates, extra grease and 19 pages of directions. There are two options to mount the motor regarding the isolators, Budd or lords mounts, I will be using the Budd mounts because they seem to fit into the nose of the Spark better. Here are several pictures of the parts just out of the box, the contra drive unit still in the box and some initial assembly of the gear-case housing assembly to the Neu motor. They have not finished with the props yet but if they look as nice as the contra unit the will be works of art. Now to the fun part and try and get this into the plane.

Dave Snow

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Old 02-10-2011, 07:56 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Hey Dave welcome to RCU! Mike
Old 02-11-2011, 01:57 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Thanks Mike.

I have almost completed the installation of the contra drive and Neu motor into the Spark and here are several pictures of the build and the almost finished install. The props on the drive are from last years batch.

Dave
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Old 02-11-2011, 03:53 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

It looks like a very clean installation Dave.

Those props looks right at home on the nose of the Spark. Mike's getting caught up with props, so I think we can send you 22x20 and 22x18 props for the version two drive next week.

By the way, see attached for the installation instructions.
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Old 02-13-2011, 07:15 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Dave,

I have never worked with composite fuselage before. Could you explain how you attached the motor mounting ring to fuselage. Also, how did you check for zero thrust?
Thanks,
Gary
Old 02-13-2011, 08:35 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

When you are satisfied with the technology and begin selling the drive, how would I place an order? Thanks.
Old 02-13-2011, 08:42 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

We are accepting deposits now for Drives that come from the batch we hope to have available sometime around the end of April. Just send me a private message if you're interested.
Old 02-13-2011, 04:06 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Hi Gary, the fuse of the Spark is composite but the front 3” is fiberglass and carbon fiber so the mounting ring is epoxy glued to this solid portion of the fuse like any firewall in a pattern would be. For the thrust we are trying to achieve zero right thrust and .5 degree down thrust, this was where the three other planes that have flown Brenner’s drive ended up at. If we assume that the wing will fly at .5 degrees positive the fuse with the wing centerline on it can be blocked off the table for 1 degree positive. After this is set the nose can be squared off to the table and then this should give us the .5 degree down thrust when the wing is flying at .5 degree positive. Hope this explains the thought process.

Dave

Old 02-13-2011, 04:33 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Would this unit be able to be used on the new Pletty IN(out)runner that Chad is testing?

I know the gearing would need to be recalculater but... could it?

Chuck
Old 02-13-2011, 04:47 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Hey Chuck,

Do have a link to the specs for this motor?

Brenner ...

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