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Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Old 02-13-2011, 05:02 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Drawing is here,

http://www.plettenberg-motoren.com/g...ce30/Masse.htm

Motor kV is 230.
Old 02-13-2011, 08:13 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Thanks for the link Chad.

As far as I can see, this motor is meant to turn a 21x14 size prop without a gearbox, and this limits it's utility with our Contra Drive because we are using a planetary gear set to share the motor power evenly between two props.

I figure that we'd need a planetary gearbox with a 1.5:1 reduction ratio between the motor rotor and the props, and the smallest practical reduction ratio I can get out of our gearbox is about 5:1. Any smaller than this and there's no room for the planet gears.

In addition, we are using just the motor without the gearbox, because we supply our own gearbox, so if we use a Neu f3a motor as a baseline, we are comparing a 375g motor to a 600g motor, which means that the whole system will gain about 8 ounces. Also, we would lose the efficiency gains we get from using an inrunner motor over an outrunner motor.

So, based on the very little I know about the Advance 30, my current thinking is that I don't think I could get it to work with its current winding, and if even if I could change the winding, the potential weight gain makes it not so practical.

Brenner ...
Old 02-14-2011, 07:15 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Hi Dave, I think I understand the thinking but am not clear on how to epoxy ring and check the thrust angles during installation. Do you tack ring with ca and then push in epoxy?
I believe there is a post of you with Wind 140. Any particular problems with that installation? What is propeller ground clearance?
Gary
Old 02-14-2011, 08:01 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Hi Brenner,

Yes the weight is an issue, although some planes are likely light enough to soak up the extra.

The motor itself is an inrunner, with a larger diameter rotor to gain the required torque, efficiency wise it should not be much different than a smaller geared inrunner motor.

That said Plettenberg does make many varieties of more conventional inrunner motors designed for use with a gearbox, it has just not been their direction for F3A, possibly one of them could mate with your drive assembly, but I would have to know what motor kV you have designed it for.




ORIGINAL: Brenner

Thanks for the link Chad.

As far as I can see, this motor is meant to turn a 21x14 size prop without a gearbox, and this limits it's utility with our Contra Drive because we are using a planetary gear set to share the motor power evenly between two props.

I figure that we'd need a planetary gearbox with a 1.5:1 reduction ratio between the motor rotor and the props, and the smallest practical reduction ratio I can get out of our gearbox is about 5:1. Any smaller than this and there's no room for the planet gears.

In addition, we are using just the motor without the gearbox, because we supply our own gearbox, so if we use a Neu f3a motor as a baseline, we are comparing a 375g motor to a 600g motor, which means that the whole system will gain about 8 ounces. Also, we would lose the efficiency gains we get from using an inrunner motor over an outrunner motor.

So, based on the very little I know about the Advance 30, my current thinking is that I don't think I could get it to work with its current winding, and if even if I could change the winding, the potential weight gain makes it not so practical.

Brenner ...
Old 02-14-2011, 09:08 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Hey Chad,

Attached is a comparision chart showing the range of motor Kv's and expected performance at the ends of the range with a Contra Drive. I have also added a typical single prop setup as well to round out the comparision.
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Old 02-14-2011, 09:11 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Hi Gary, after getting the nose set to the proper angles, this was the key for this installation, the typical installation of a firewall in any fiberglass pattern plane was used. 1) tack some spacers to the front of the nose, approx 3/32". 2) tack the spinner – in my case the front gearbox cover – to the spacers centered on the nose of the plane. 3) slide the assembled motor/soft mount/fuse ring (AKA firewall) into the plane behind the spinner and attach to the spinner, see first picture in post #118 for this assembly. 4) tack glue the fuse ring to the fuse – I used 5 min epoxy but thick ca could be used if you have a good fit. 5) remove motor/soft mount from spinner and fuse ring, remove spinner from nose of plane. 6) complete gluing of fuse ring to fuse – I used Aeropoxy from BVM. At this point the fuse ring is installed and aligned to the nose of the plane. There is a lot of trial fits of the firewall to get a good fit to the fuse but it just takes time here.
I do have a Wind S Pro with the version 1 contra in it and the same process was followed to install it as described above. The props used are 22” diameter and all the current 2m electric pattern planes that I can think of should have adequate ground clearance.

Dave
Old 02-14-2011, 10:06 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Thanks Dave. Your input has been very helpful. One more question. What technique do use to remove material from nose to set proper angels?
Gary
Old 02-14-2011, 11:17 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Gary, typically there would not be any need to remove any material, the manufacture/designer will have set the proper thrust into the nose of the plane. However when using the contra drive the thrust in the nose will need some adjusting and adding material would be the easiest way to do that, a tapered ring can be glued to the nose to set the zero right and .5 down thrust. The Spark (older version) is a special case because the plane uses a 64 mm spinner but the contra drive is 82 mm. In this case I set up a marking jig with the proper thrust on the nose, marked where to cut and then cut/sanded to the mark. At this point the nose was not completely round so I added a forming ring about 3/16” behind the cut line and used ca to glue in place. This ring was temporary so I used a glass/foam composite material that would be easy to sand/remove later after the main fuse ring was installed, this ended up being about 1/2” behind the cut line. I have attached several pictures of the high precision equipment and the set up used to give the plane the nose job. Hope this helps but again this was a special case and adding material would be my normal choice not cutting up an expensive fuse.

Dave

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Old 02-14-2011, 11:46 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Only a pro would have the moxy to try that with a new plane.

NICE JOB!!!!

Verne


ORIGINAL: Dsnow

Gary, typically there would not be any need to remove any material, the manufacture/designer will have set the proper thrust into the nose of the plane. However when using the contra drive the thrust in the nose will need some adjusting and adding material would be the easiest way to do that, a tapered ring can be glued to the nose to set the zero right and .5 down thrust. The Spark (older version) is a special case because the plane uses a 64 mm spinner but the contra drive is 82 mm. In this case I set up a marking jig with the proper thrust on the nose, marked where to cut and then cut/sanded to the mark. At this point the nose was not completely round so I added a forming ring about 3/16” behind the cut line and used ca to glue in place. This ring was temporary so I used a glass/foam composite material that would be easy to sand/remove later after the main fuse ring was installed, this ended up being about 1/2” behind the cut line. I have attached several pictures of the high precision equipment and the set up used to give the plane the nose job. Hope this helps but again this was a special case and adding material would be my normal choice not cutting up an expensive fuse.

Dave

Old 02-14-2011, 12:33 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Verne,

At this rate you are going to need lots of "washing machine repellent" for your planes. There will be several of these in the you area flying,

Arch
Old 02-14-2011, 01:07 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

You'd probably be surprized to learn that the basic principles behind the Contra Rotating Drive are used in certain High Efficiency Vertical Axis Washing Machines to more efficiently input mechanical energy into the wash load.

The power into the system is split and shared between the impeller and the wash basket so that the clothes gets pulled in one direction by the impeller, and the reverse direction by the wash basket. This shortens wash time, and minimizes fabric damage. Some of these machines have water efficiency, energy efficiency, and cleaning efficiency that are comparable to front loaders, but with shorter wash times, and better walk and vibration performance.

Brenner ...
Old 02-14-2011, 01:21 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Hi,
Team Ireland rec'd their contra drives today.
They are a credit to the guy's; Brenner and Mike.
The workmanship is exceptional and it stands testament to the design which speaks for itself.
Even the packaging is well thought out and executed.
So well done guys.
We have already been nick-named the 'Contra Rebels'.
All that's req'd now is for our weather to pick up a little and for us to cut the front off a few models to install these beauties. Just kidding but we will square the front ends up to suit.
My interest in this was initially aroused by the 'E Factor' system but this got tied up and put on the market at in excess of €3000.00 (complete with motor and esc) that's over $4000.00. However the other ,and more important, issues are the length of that unit and that there are no speed/performance options with it. It is quite slow. Slow as it may be it still performed very well in the EC's Austria last year, but that was very calm weather.
I wont speculate about the benefits now but I will report back here with flight reports when set up and when the weather permits some flying, ie enough to evaluate properly.
We were given some really great encouragement re contra drives in Austria , the guy's might chime in here, between what we saw and what some people said.

Brian
Old 02-15-2011, 07:13 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Dave Snow usually flies FAI locally so I'll probably only have to worry about Brenner for the time being. If Fortino comes back and buys a contra, I'm either quitting or moving up to FAI....

Verne


ORIGINAL: rcpattern

Verne,

At this rate you are going to need lots of ''washing machine repellent'' for your planes. There will be several of these in the you area flying,

Arch
Old 02-15-2011, 07:30 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Hey Verne,

I had a lot of fun chasing you and Mike Meuller last year. I'd hate too see you quit or move up to FAI, but it's worse than you thought. I have a Contra Drive sitting right here for Bob Kane, and I think Dennis is interested in getting one as well.

Brenner ...
Old 02-15-2011, 07:54 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Dave plans on flying a lot of Masters this year. Soooooo. Better get in some serious practice. I have some new secret weapons too. Mike Mueller
Old 02-15-2011, 09:13 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Mike,

I know its a long trip for you guys, but Larry Kauffman and myself are working on getting a regional championship in northern, VA this fall. I'll let Larry give all the details once we have them, but we are hoping to be able to turn this into a very large contest,

Arch
Old 02-15-2011, 09:17 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Geez,

D4/D5 Masters is going to be brutal this year. Especially if Archie shows up at the D4 Championship in September. I think I'll move on up to FAI and let Mark and Mike beat up on me. (just kidding. I wouldn't miss the street fight in Masters for anything ...)
Old 02-15-2011, 10:02 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Brenner,

Tentatively a fairly large group from this part of the country are coming over for the D4 Champs. We've adjusted contest schedules over here to allow a bunch of us to car pool over. Hopefully some of the D4 guys can hit some of our contests this year as well. We will have at least 1 (probably 2) in northern, VA, and also my contest in Maryland in June.

Arch
Old 02-15-2011, 12:17 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Kane's still got an Integral kit that's been laying around his garage for 4 years. I figure it'll be done about the time it's SPA legal. I wonder if the Contra will be legal about the same time?

Dennis is probably just pulling your chain as am I.

I'm not going anywhere, Maytag man.... [>:]

Verne


ORIGINAL: Brenner

Hey Verne,

I had a lot of fun chasing you and Mike Meuller last year. I'd hate too see you quit or move up to FAI, but it's worse than you thought. I have a Contra Drive sitting right here for Bob Kane, and I think Dennis is interested in getting one as well.

Brenner ...
Old 02-15-2011, 12:54 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Brenner your too young and good looking to fly in Masters anyways.
Arch nothing would please me more than to come over to your contests. Now if I could onlyget clearance from the boss.
If I were single I'd try toset the modern dayrecord for the most contests in a year. Couldn't beat Dave Brown who regularly went to as many as 20 a year. My personal record was 14. Mike
ORIGINAL: Brenner

Geez,

D4/D5 Masters is going to be brutal this year. Especially if Archie shows up at the D4 Championship in September. I think I'll move on up to FAI and let Mark and Mike beat up on me. (just kidding. I wouldn't miss the street fight in Masters for anything ...)
Old 02-15-2011, 01:18 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

I would also love to attend some of Archie's contests. If there are no conflicts, I'm in!

Mike, you are too kind. Not wrong, just too kind ...

Verne, I actually do have a Drive here for Bob if he wants one. He asked for one way back last summer for his Integral like you mentioned. As for Dennis, I did tell him that I would sell a Drive to even him.

Brenner ...
Old 02-15-2011, 08:50 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

I have responses but I'll hang on to them lest they're misunderstood. I start getting a little chippy this time of year and my humor gets a bit too much bite to it. Man, I wish this snow would melt....

Verne


ORIGINAL: Brenner

I would also love to attend some of Archie's contests. If there are no conflicts, I'm in!

Mike, you are too kind. Not wrong, just too kind ...

Verne, I actually do have a Drive here for Bob if he wants one. He asked for one way back last summer for his Integral like you mentioned. As for Dennis, I did tell him that I would sell a Drive to even him.

Brenner ...
Old 02-15-2011, 09:20 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Verne,

You can always come out to Yuma. I probably dont need to tell you have many flights I have gotten in again do I?

Andrew
Old 02-15-2011, 11:14 PM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Well i am now working mandatory six days a week and probably later this week mandatory 7 days. I'll be lucky to go flying at all, much less need a contra drive. I've made exactly three flights on a pattern plane since Hebron in September. Why could'nt i have been born rich instead of good looking? At least i still have a good hairline.
Old 02-16-2011, 04:15 AM
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Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Hey Dennis, pattern flying wouldn't be the same in D4 without you. Let's hope that you can get back to five days a week before spring.

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