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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 04-03-2016, 05:28 AM
  #1626  
Bubblehead575
 
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Brenner

The bearing and grommet in the rear motor mount (shaft support) came out in flight. Have you seen this before and what is the fix. Is there an alignment problem or do I need to put a few drops of CA on the grommet when I install it? I reached out to Mike at F3A for a replacement.
Old 04-03-2016, 05:36 AM
  #1627  
Brenner
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Originally Posted by Bubblehead575
Brenner

The bearing and grommet in the rear motor mount (shaft support) came out in flight. Have you seen this before and what is the fix. Is there an alignment problem or do I need to put a few drops of CA on the grommet when I install it? I reached out to Mike at F3A for a replacement.
We have had one other instance of this happening. The solution is to us CA to fix the needle bearing into the grommet.

Send me a private message with your mailing address, and we'll send you a replacement bearing.

Brenner ...
Old 04-03-2016, 06:32 PM
  #1628  
rgreen24
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Also, grease your bearing with the grease that Brenner send with the drives. Brenner mentioned this a few posts ago, and it has seemed to do the trick.
Old 04-20-2016, 11:07 AM
  #1629  
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We have started to hear more reports of the rear support needle bearing working free from its rubber grommet, so we have decided that it's appropriate for us to redesign this particular part, and send out replacements to all existing customers.

What we are going to do is machine a pair of needle bearing endcaps that will go over each end of the bearing, and clamp it in place.

This is a screenshot from our CAD model that shows what I mean:




These endcaps will work with the existing needle bearing and the existing carbon fiber support plate, except that six holes need to be drilled through the plate for the bolts. However, the endcaps can be used as a jig to do this.

The needle bearing and the rubber grommet need to be removed first, and the grommet can then be discarded.

There is a pilot boss in the rear face of the endcaps that fits into the existing hole in the support plate that can be used to align the endcaps with the support plate. This will allow the three top holes in an endcap to be used as a guide to drill the first three holes.

The endcaps can then be assembled with three bolts, and the three holes on the reverse side of the endcap can then be used as a guide for the remaining three holes.

The needle bearing is a light press fit into the center hole in the endcaps. It should be possible possible to push the parts together by pressing with a hand. The bolt holes in the caps can be aligned with some sort of pin before the parts are pressed together.

The endcaps are going to made from black Celcon/Acetal plastic, so the assembly should still be pretty light, and the encaps should also match up well with the black carbon fiber support plate.

We are planning on having these ready to ship free of charge this coming Monday. We have a list of all customer we have shipped Drives to, and we will use this list, but if you want to be sure that you are on our list, please send me a PM through RCU with your shipping address.

Both Mike and I apologize for this needle bearing grommet problem, and we are both very much dedicated to making sure that the V4 Contra Drive works for everyone.

Everything will go out USPS Priority Mail.

Brenner ...
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Old 04-20-2016, 02:59 PM
  #1630  
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Very nice response to a possible issue.
Old 04-30-2016, 11:41 AM
  #1631  
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Rainer Hacker from Hacker Motors has just sent us a pair of Hacker Outrunner motors to try.

These are motors that Hacker has modified with an extended shaft for use with the V4 Contra Drive. The mounting hole pattern is the same as what we currently use, and the motor length is the same as well, but the rear shaft has an 8mm diameter versus the 6mm diameter that we use now, so we will need a new rear support.

I have no idea how this motor will work, but on paper it should work well. My plan is to try it in the coming weeks.

Brenner ...

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Old 04-30-2016, 02:04 PM
  #1632  
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Sounds like another good option for us. I got the new the rear support in the mail today and installed it. Took about 20 minutes from start to finish and it's pretty slick. After greasing the needle bearing with the rubber grommet, i have had no further issues. So, it will be interesting to see if there are any different flight characteristics changes without the rubber grommet. I suspect not. Thanks for getting the parts out so quickly. As always Brenner you provide GREAT customer service. All the best with your testing of the Hacker.

Last edited by rgreen24; 04-30-2016 at 05:04 PM.
Old 04-30-2016, 02:34 PM
  #1633  
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Got mine today too.

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Old 05-01-2016, 08:51 AM
  #1634  
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Mike Gaishin has been trying a new set of vibration grommets from EAR Specialty Composites.

These grommets are specifically designed to minimize vibration amplitude at resonance, and isolate it above resonance. The damping factor of the material they use is formulated specifically for this purpose.

These are what Mike is using. They are a drop-in replacement for the Budd Engineering grommets. Mike is still using the nylon bushing, the bolt, the carbon fiber plates, and the carbon fiber washers that we ship with each Drive.



I have just installed a set on my plane, and so far I am very impressed. Any resonance that exists when I spin my Drive up is very hard to notice, if at all, and the isolation at max throttle is excellent.

They are available molded with several materials, but the ones I have are made with C-1002 material which is blue.

Right now I don't know how durable or reliable they will be, but I am going to be testing them in the coming weeks, so I hope to find out.

Regardless though, if anyone want to try them, they can be purchased from McMaster-Carr. The part numbers are: 9311K145, & 9311K143.

Brenner ...
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Last edited by Brenner; 05-14-2016 at 10:45 AM. Reason: Part Number was wrong ...
Old 05-01-2016, 09:53 AM
  #1635  
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This graph shows what's happening:



At the resonant frequency of the system the amplification factor with Natural Rubber is from 15 to 20 times the unamplified displacement, whereas the EAR Specialty Composites C-1002 material has an amplification factor of less than 1.5 at the resonant frequency of the system.

Also the vibration isolation for both materials isn't significantly affected at maximum rpm.

This is definitely what we need. The only unresolved issue is the potential for the carbon fiber plates to wear away the C-1002 material prematurely. This is a potential issue because C-1002 is a thermoplastic material, whereas natural rubber is a thermoset material, and thermoset materials have their molecules cross-linked during the cure process, which gives them superior mechanical properties over thermoplastic materials, including better wear resistance.

If this does turn out to be an issue I will try inserting UHMW (or similar material ..) plastic disks between the grommets and the carbon fiber plate. We can also try replacing the carbon fiber plate material with a G10 composite material as well. which has a smoother surface.

Brenner ...
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Old 05-04-2016, 10:24 PM
  #1636  
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You are a lucky guy. I don't receive mine.
Old 05-05-2016, 01:01 AM
  #1637  
Brenner
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Hey Vincent,

Yours is in the mail, but international mail takes a lot longer than domestic mail in the USA.

Brenner ...
Old 05-06-2016, 02:43 AM
  #1638  
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Hey Brenner,
What you say is very logical.
The problem is that the trace of the package is lost since April 30 when the package is out of Chicago. No customs notice. From this side of the Atlantic it looks like the Bermuda Triangle and nothing is logic.

Vincent ...
Old 05-06-2016, 08:25 AM
  #1639  
Brenner
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Hey Vincent,

I think that is because I sent your package via USPS Priority Mail. My understanding is that USPS Priority Mail provides tracking only with the borders of the United States.

If you don't receive anything in another week, I'll resend .

Brenner ...
Old 05-06-2016, 11:28 AM
  #1640  
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Hey Brenner,

Thank you very much for this option.

Vincent ...
Old 05-10-2016, 08:27 AM
  #1641  
mups53
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Hi Everyone
The Falcon CRP props are proving to be popular.
Late next week I'll be taking on 4 new sizes
C2CR2318F
C2CR2320F
C2CR2320R
C2CR2322R

I'll list them very soon on F3AUnlimited.com
http://www.f3aunlimited.com/contra/c.../falcon-contra.
If interested you can ask for an instant notification when they arrive.
Now this is something I can see is a pending problem. With clearance an issue already on the 22" props the added 1/2 inch per side could be restrictive,
I've asked Falcon to develop a new set of longer gears to help out. The new landing gears will be an inch longer.
Take care. Also thanks Mike and Brenner for your proactive approach towards handling issues.
Mike Mueller
Old 05-10-2016, 12:14 PM
  #1642  
MTK
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Brenner,

McMaster Carr carries sticky back Teflon tape. They carry it with two different adhesives, acrylic and silicone. For electrics, either adhesive is fine. Tape comes in various thicknesses. That might help your grommet wear
Old 05-12-2016, 11:25 AM
  #1643  
Anthony-RCU
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Originally Posted by Brenner
Mike Gaishin has been trying a new set of vibration grommets from EAR Specialty Composites.

These grommets are specifically designed to minimize vibration amplitude at resonance, and isolate it above resonance. The damping factor of the material they use is formulated specifically for this purpose.

Regardless though, if anyone want to try them, they can be purchased from McMaster-Carr. The part numbers are: 9311K145, & 9311K144.

Brenner ...

Looks like you used 9311K143 not the K145. I ordered 9311k145 and they are WAY TOO big to use.
Old 05-14-2016, 10:34 AM
  #1644  
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Hey Anthony, Sorry, my bad...

You are right. There are two sizes, and the one that works is the smaller size.

The JPEGs are correct, but one of the part numbers I listed is wrong.

The correct part numbers are:

9311K145
9311K143

I apologize for the confusion.

Brenner ...

PS-> I've edited my post and corrected the numbers....

Last edited by Brenner; 05-14-2016 at 10:46 AM.
Old 05-14-2016, 10:34 AM
  #1645  
Brenner
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Originally Posted by MTK
Brenner,

McMaster Carr carries sticky back Teflon tape. They carry it with two different adhesives, acrylic and silicone. For electrics, either adhesive is fine. Tape comes in various thicknesses. That might help your grommet wear
Hey Matt,

Thanks for the tip.

Brenner ...
Old 05-18-2016, 12:48 PM
  #1646  
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First flights on the pretty blue isolators and they worked very well. Took out the little off idle vibration I had and changed the sound of the plane. After a few flights the plane kept getting quieter as the gears re-seated themselves. Nice upgrade.
Old 05-19-2016, 02:35 PM
  #1647  
mups53
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The new highly anticipated 23" Diameter Falcon Props are now listed and ready for sale. We expect to start shipping on Monday.
Here are the listings:
23x18 and 20 Fronts
23x20 and 22 Rears
They include a nice set off Falcon Prop Covers and their own protective box.
Light and stiff these have proven to be very popular.
Also some of the out of stock Falcon Contra sizes are back in stock.
http://www.f3aunlimited.com/falcon-c...-set-of-covers
http://www.f3aunlimited.com/falcon-c...-set-of-covers
http://www.f3aunlimited.com/falcon-c...-set-of-covers
http://www.f3aunlimited.com/falcon-c...-set-of-covers
New longer Falcon gears are under construction and will be ready in about 4 weeks.
Thanks for asking for these.
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Old 05-20-2016, 04:31 PM
  #1648  
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That's great news Anthony, I just ordered a set today as well. My v4 drive is running very well. In Muncie today for the first contest of D4 with some moderate winds. 13mph out of the east. I am putting about 3400mah back in my packs. On a calm day, I put about 2900mah back in the packs and I am not using the throttle tech. The motor is extremely efficient and I am running the 22x20 front and 22x22 rear. I use the props for all conditions whether it's calm or windy.
Old 05-20-2016, 04:55 PM
  #1649  
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Originally Posted by rgreen24
That's great news Anthony, I just ordered a set today as well. My v4 drive is running very well. In Muncie today for the first contest of D4 with some moderate winds. 13mph out of the east. I am putting about 3400mah back in my packs. On a calm day, I put about 2900mah back in the packs and I am not using the throttle tech. The motor is extremely efficient and I am running the 22x20 front and 22x22 rear. I use the props for all conditions whether it's calm or windy.
Robert, you are flying an Agenda, correct? I have the same setup on mine and consume on average 3300mah per flight with judicious throttle management with a Throttle Tech. I still like my Pletty powered Invitation better with a 21.5X13 2 blade or 19.5X13 3-blade Falcon prop over the Contra powered Agenda. The plane just feels too draggy and I just can't see the color scheme and wing planform as well as that on the Invitation. Plane is for sale. If ya can't see it, no sense flying it.
Old 05-20-2016, 10:28 PM
  #1650  
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Would you consider remonokotiing the wings?

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