Electric Pattern Aircraft Discuss epowered pattern aircraft in this forum

Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Reply
Old 04-12-2011, 06:30 AM
  #226
Brenner
Thread Starter
 
Join Date: Jul 2007
Location: Bridgman, MI
Posts: 721
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Hey nicepoz,

If you are interested in purchasing a Contra Drive from our next batch, which will become available in late May, you can send me a private message through RCU and I will help you make the arrangements.

The current pricing structure that we are using is as follows:

Contra Drive (includes one Replaceable Gearset, and Spinner Assembly, but does not include props, or electric motor...): $1,000 USD
Set of Front & Rear Propellers (22X18, and 22X20 sizes are currently available ...): $200 USD
Replaceable Gearsets (9.98:1, 10.15:1, 10.33:1 Gear Ratios Available...): $200 USD
Motor Adapter Manifold & Carbon Fibre Mounting Plates (Hacker C50, & Neu f3a Motors Supported ...) $100 USD
Custom Color (Yellow is standard at no extra Charge ...) $100 USD

The length of the Contra Drive Spinner is 85mm, which fits perfectly within the 2m limit on my Carf Integral.

Brenner ...
Brenner is offline  
Reply With Quote
Old 04-12-2011, 09:09 AM
  #227
Mike Wiz
 
Join Date: Jan 2002
Location: Fenton, MI
Posts: 941
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

... Gulp... Those are really nice Brenner but definitely not cheap.
Mike Wiz is offline  
Reply With Quote
Old 04-12-2011, 09:57 AM
  #228
wattsup
 
Join Date: Jan 2009
Location: Franklin, TN
Posts: 599
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Step up Mike, it's only money! Regards, Everette
wattsup is offline  
Reply With Quote
Old 04-12-2011, 10:03 AM
  #229
rcpattern
 
Join Date: Oct 2003
Location: Great Mills, MD
Posts: 2,860
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

For the amount of tooling and machining that went into it, I would say that is more than reasonable. The gearbox alone for a Neu motor without the contra system is around 300.00. I remember reading somewhere I believe in this thread that the labor was donated. The workmanship on these units are first class without a doubt, and I'm definitely looking at getting a pair for next year.

Arch
rcpattern is offline  
Reply With Quote
Old 04-12-2011, 10:53 AM
  #230
TonyF
 
Join Date: Dec 2001
Location: Rosamond, CA
Posts: 2,077
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

And the really neat thing about it, it can have a "Made in the USA" sticker on it. What high tech item in the hobby can say that anymore?

I tried the 22x18 on the front. It definitely had a different sound, but I preferred the performance of the two 22x20's. Actually, I trimmed 1/4"off each tip now and that seems to be working, but it was a very minor difference.
TonyF is offline  
Reply With Quote
Old 04-13-2011, 06:40 PM
  #231
Dsnow
 
Join Date: Feb 2011
Location: Palatine, IL
Posts: 149
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Finally we were able to get out to the field after 5 months, felt great to get the first 3 flights on the new Spark in light winds and mid 60’s degree temps. The plane tips the scales at 10 lbs 11 oz with Rhino 4900 25c batteries, wood built-up wings/stab and rudder. The Neu motor, Brenner’s contra drive, 10.15:1 gear ratio and 22x20 props, the amps topped out at 88 and watts at 3300. The first thing we noticed while flying was the sound, it's very quiet compared to the version 1 contra drive and is not a distraction like last year, great job Brenner on the redesign. The second thing I noticed was the speed, much better - faster - than the V1 and very similar to what I was getting with the single prop setup. The plane is pulling slightly to the canopy so I did not make a good guess on the thrust line, just needs a little bit more down thrust. The plane seems very near final trim, I think it needs a bunch of little changes on throws and expo rates to get the feel just right. The plane feels very stable and I did not notice any yaw issues yet that Brenner and I experienced last year with several different planes, the thick trailing edge on the rudder may be helping but I would need to use the standard rudder to verify this - maybe later. I'm still charging but I think the battery drain will be similar to last year with the single prop setup, will know more later with more flights. So far it looks very good, thanks Brenner and team for all your great work.

Dave
Attached Thumbnails
Click image for larger version

Name:	Mk24832.jpg
Views:	101
Size:	127.1 KB
ID:	1593636  
Dsnow is offline  
Reply With Quote
Old 04-15-2011, 08:39 AM
  #232
servari
 
Join Date: Oct 2008
Location: Colmar, FRANCE
Posts: 40
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Hi Dave,

The flights are wonderful with contra drive
Have you tried 22X18 in front and 22X20 for the rear ??

Vincent ...
servari is offline  
Reply With Quote
Old 04-15-2011, 10:32 AM
  #233
RC_Pattern_Flyer
 
RC_Pattern_Flyer's Avatar
 
Join Date: Aug 2004
Location: San Antonio, TX
Posts: 1,119
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

I would consider moving your CG forward first before adjusting your thrust. The closer to zero you are the better the plane will fly in all orientations.

Do you have any coupling with rudder currently as well? If yes....moving the cg forward will help alleviate some if not all of this as well.

Chuck
RC_Pattern_Flyer is offline  
Reply With Quote
Old 04-15-2011, 10:44 AM
  #234
Dsnow
 
Join Date: Feb 2011
Location: Palatine, IL
Posts: 149
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Hi Vincent, I hope to try that the next time we get out but the weather does not look good for the next week.

Dave
Dsnow is offline  
Reply With Quote
Old 04-15-2011, 12:25 PM
  #235
Dsnow
 
Join Date: Feb 2011
Location: Palatine, IL
Posts: 149
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Hi Chuck, with only three flights on the plane it's hard to know exactly what it's doing but from the other Spark I was flying the cg is already forward from that plane, that is why I think it's more a thrust issue not the cg. Not sure if you saw earlier posts - #118 page 5 - but the nose of the Spark was modified to fit the spinner size and I may not have gotten the thrust set properly, but it's easy to change and if needed the nose can be sanded to match a new thrust line. The plane did not pitch or roll significantly in knife edge, only a slight pull on the up lines and the typical pull to the canopy on the down lines. I'm sure once the plane and I have more flights there will be other things to look at but so far it's looking very promising and hope the weather starts to warm up soon.

Dave
Dsnow is offline  
Reply With Quote
Old 04-15-2011, 07:21 PM
  #236
RC_Pattern_Flyer
 
RC_Pattern_Flyer's Avatar
 
Join Date: Aug 2004
Location: San Antonio, TX
Posts: 1,119
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Dave... looking back, forgot you had modified the front. good luck with the trimming. I begin a new setup tomorrow with my Beryll and hope to get it finished by the end of the day. Then its onto setting snaps and spins oh ya.


Chuck
RC_Pattern_Flyer is offline  
Reply With Quote
Old 04-16-2011, 08:40 PM
  #237
shannah
 
Join Date: Sep 2004
Location: placentia, CA
Posts: 1,079
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Hi Brenner and Mike,

Hats off to you guys. I am really impressed with the work you have done. I watched this thing in action today flown by Tony F. I think its pretty cool. I am thrilled to see this come out of SW Michigan!!! I remember Mike flying with my Dad, Bill, back a million years ago. You've put the spot back on the map years after the demise of Heathkit radios...LOL. After Tony's last flight today I have to say that I'm wanting one. I think it needs an airframe designed around it. It really is something unique! It is far better than the videos I have seen of Seba's initial contra unit. Yours had a nice consistent speed and not artificial looking.

Great Job guys.
Steve Hannah
shannah is offline  
Reply With Quote
Old 04-17-2011, 08:47 AM
  #238
Brenner
Thread Starter
 
Join Date: Jul 2007
Location: Bridgman, MI
Posts: 721
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Hey Steve,

Thanks for the kind words. I'm really glad that Tony has been able to demonstrate the Contra to you guys out on the West Coast.

Mike has told me lots of stories about the Heathkit days. I even have an old optical heathkit tachometer that Mike says he actually designed back in the day, and I pass by the old Heathkit buildings every day on the way to work.

There are a couple of guys looking at airframes that would best suit the Contra. Flying a Contra changes how a plane behaves probably more than anything else you can do to a plane, and what we've discovered is that some planes work very well with the Contra, whereas other planes need small changes. For instance, I think the Wind S and the Spark seem to adapt well right out of the box, but my Integral needed the addition of a pair of 1/2 inch triangular strips to the trailing edge of the rudder to reduce rudder sensitivity around neutral and prevent yaw oscillations when the rudder is released too quickly. Mike has a plane that he designed himself that needed this same modification as well.

I think any plane can be trimmed to fly well with a Contra Drive, but elimination of motor right thrust will cause plane designs to evolve so that additional drag is added to the tail of the plane to replace the drag that now results from motor right thrust. This will probably involve thicker rudder profiles, larger rudder fins, and/or larger/thicker stabs. Also, aerodynamic drag is no longer needed to limit speed on the downlines, because the dual propellers in a Contra Drive provide more than enough braking effect to slow any plane down. This means that fuselages and wings can become slimmer, which will potentially reduce battery consumption due to lower parasitic drag, and perhaps improve entries into snaps and spins.

Brenner ...
Brenner is offline  
Reply With Quote
Old 04-18-2011, 09:01 AM
  #239
Angus Balfour
 
Angus Balfour's Avatar
 
Join Date: Oct 2004
Location: Mullingar, IRELAND
Posts: 904
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Well I successfully maidened my new contra powered Valiant. The model and power system seem very well suited and early indications are that it flys extremely well. My set up is as follows:

Brenner contra
C-ARF Valiant
YGE 90 controller
F3A Unlimited packs

I completed 7 flights over the weekend six of which were with the 10.33:1 gears. Maiden was with 22X20 rear and 22X18 front and I then completed a few flights on the 22X20’s front and rear which did give slightly more speed. The last flight I put in the 10.15:1 gears and mixed props which gave slightly more performance than the 10.33:1 and two 22X20’s. I think I will stick with this for the moment as I can prop up for strong wind. One thing that struck me was how controllable the whole thing was. Tons of braking (no brake programmed in the esc) and huge amounts of pull. Verticals were simply effortless. Compared to my YS powered Osmose I felt it was more controllable speed wise. It didn’t “wind up” in horizontal flight if you left it in too high a power setting. Braking was better also which meant you could fly a smaller closer in schedule much more easily. A few observations:

1) The model did feel fairly sensitive in all three axes. Perhaps this is just the plane or perhaps the contra. It wasn’t unstable, just sensitive. I have the strake to try on the Valiant and I will probably try a rudder flare. Although to be honest it is still very useable as is
2) No right thrust required even when mixing props
3) 0.5 degree down thrust seems fine for the Valiant
4) Speed is much better than the E-factor unit
5) Sounds much better than the E-factor unit, less “whiney”.
6) Static thrust is way more than a YS 170, top speed still not as high but I have another gear set down to try and also a higher pitch front prop. Speed as is seems very good
7) Very easy to change the gears at the field
8) Reduced rudder required when pulling/pushing
9) No torque effect during stall turns
10) The quality of workmanship on the drive and props is superb

So overall I’m very impressed with the drive and plane and can’t wait to get some more time on it.
Attached Thumbnails
Click image for larger version

Name:	Yw68304.jpg
Views:	109
Size:	157.7 KB
ID:	1595652   Click image for larger version

Name:	Oj27374.jpg
Views:	196
Size:	115.0 KB
ID:	1595653   Click image for larger version

Name:	Wb74740.jpg
Views:	77
Size:	167.0 KB
ID:	1595654   Click image for larger version

Name:	Ic83922.jpg
Views:	79
Size:	177.4 KB
ID:	1595655   Click image for larger version

Name:	Ig11233.jpg
Views:	77
Size:	142.3 KB
ID:	1595656  
Angus Balfour is offline  
Reply With Quote
Old 04-18-2011, 10:47 AM
  #240
mithrandir
 
mithrandir's Avatar
 
Join Date: Jul 2003
Location: adelanto, CA
Posts: 1,140
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

All I can say is *****in!!

Ain't 'lectric Gnarly!!

I will have me one of these setups someday!!
mithrandir is offline  
Reply With Quote
Old 04-21-2011, 02:07 PM
  #241
Brenner
Thread Starter
 
Join Date: Jul 2007
Location: Bridgman, MI
Posts: 721
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

These pictures are from Dmitry Zagitov. I asked him if I could post them, and he agreed.

This is Dmitry's "Angel's Shadow" that he has fitted with a Contra Drive. The plane was designed and built by Vladimir Kozlovsky. Vladimir also installed the Contra Drive as well. I am glad to be able to show these pictures because not only is the plane beautiful, but both the craftsmanship and the Contra installation are immaculate. Also, the installation pictures show very clearly and consicely how the Contra is installed.

Again, my thanks to Dmitry for allowing me to post these.

Brenner ...
Attached Thumbnails
Click image for larger version

Name:	Mh21190.jpg
Views:	288
Size:	112.9 KB
ID:	1597187   Click image for larger version

Name:	Sx61102.jpg
Views:	184
Size:	179.6 KB
ID:	1597188   Click image for larger version

Name:	Fw27849.jpg
Views:	192
Size:	153.0 KB
ID:	1597189   Click image for larger version

Name:	Eg78325.jpg
Views:	271
Size:	71.0 KB
ID:	1597190   Click image for larger version

Name:	Hg21376.jpg
Views:	229
Size:	112.3 KB
ID:	1597191   Click image for larger version

Name:	Ut25913.jpg
Views:	574
Size:	58.4 KB
ID:	1597192   Click image for larger version

Name:	Kw98631.jpg
Views:	277
Size:	56.5 KB
ID:	1597193   Click image for larger version

Name:	Fl56194.jpg
Views:	252
Size:	54.4 KB
ID:	1597194  

Click image for larger version

Name:	Wh38359.jpg
Views:	264
Size:	70.4 KB
ID:	1597195   Click image for larger version

Name:	Wt59204.jpg
Views:	242
Size:	51.4 KB
ID:	1597196   Click image for larger version

Name:	Kf12748.jpg
Views:	253
Size:	62.0 KB
ID:	1597197   Click image for larger version

Name:	Ig11188.jpg
Views:	253
Size:	64.7 KB
ID:	1597198  
Brenner is offline  
Reply With Quote
Old 04-21-2011, 09:26 PM
  #242
wattsup
 
Join Date: Jan 2009
Location: Franklin, TN
Posts: 599
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Brenner, thanks for posting Zagitov's pictures. After seeing all the peices and parts of the Contra drive laid out in one of the above pictures and think I finally understand what I'm looking at. It will probably be just a matter of time before I place my order. Thanks again, Everette
wattsup is offline  
Reply With Quote
Old 04-24-2011, 09:27 AM
  #243
Dsnow
 
Join Date: Feb 2011
Location: Palatine, IL
Posts: 149
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

I was able to get out and fly 9 flights yesterday in calm 65 deg damp air with Bill Ahrens and Ed White and am very happy with the contra drive and plane. The contra is providing very constant speeds and great pulling power over the tops of maneuvers. We did try the 22x18 front prop and 22x20 back prop with the 10.15:1 gear set and we all thought the plane looked good and performed better with this setup, it did not have more power or speed just looked smoother and very consistent speed through all the maneuvers. So far no mix is required for knife edge flight but I do have down elevator to throttle mixes for both high and low stick position, it still needs just a little bit more down thrust. Here are several pictures of the plane.

Dave
Attached Thumbnails
Click image for larger version

Name:	Ay74795.jpg
Views:	138
Size:	97.8 KB
ID:	1598352   Click image for larger version

Name:	Xt60326.jpg
Views:	120
Size:	97.0 KB
ID:	1598353   Click image for larger version

Name:	Io29173.jpg
Views:	82
Size:	93.5 KB
ID:	1598354   Click image for larger version

Name:	Au55707.jpg
Views:	99
Size:	74.2 KB
ID:	1598355  
Dsnow is offline  
Reply With Quote
Old 04-24-2011, 01:25 PM
  #244
Jason Arnold
 
Jason Arnold's Avatar
 
Join Date: Aug 2005
Location: Sydney, AUSTRALIA
Posts: 1,301
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

G'day Dave,

Your model looks great!

Try a little more incidence in the wing to resolve your pull to the canopy. This is easier to adjust than the trust line.... You may also need to play with the CG for your KE.

What did it end up weighing with the contra drive system?

Cheers,
Jason.
Jason Arnold is offline  
Reply With Quote
Old 04-24-2011, 01:36 PM
  #245
Brenner
Thread Starter
 
Join Date: Jul 2007
Location: Bridgman, MI
Posts: 721
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Hey Dave,

Did you shorten the rudder. It looks shorter. I like the thickened profile. How does the Spark track with this profile?

Brenner ...

PS-> Hey Jason, Dave mentioned the weight as 10 lbs 11 oz back in post 18. This is equivalent to 4.86 kg.
Brenner is offline  
Reply With Quote
Old 04-24-2011, 02:41 PM
  #246
Dsnow
 
Join Date: Feb 2011
Location: Palatine, IL
Posts: 149
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Hi Jason, the plane does weigh 10 lbs 11 oz - post 231 - and I've been thinking about changing the wing incidence and may try that next time out but I like the way the fuse looks in the air and not sure I want to change that. Currently the knife edge is great so I think the cg is in a good spot, the dihedral correct on this series of wood wings to eliminate the roll couple and the anhedral stab to eliminate the pitch couple of our previous Sparks. Mike Mueller will be flying his Spark/ Hacker Q80 combo soon with the wing and stab I built for him so we should know more if the wing dihedral and anhedral stab works for him and requires no mix

Hi Brenner, yes I finally got around to cutting about 3/4" off the rudder to be legal and it's still extremely effective. I will need to use the stock rudder to see how much it's actually helping but so far the plane feels very stable in yaw even at some slow speed exits of maneuvers where we saw the instability of the three planes last year. Do you have a picture of your modified rudder? I know you had an experimental one last year but what does the finished one look like?

Dave
Dsnow is offline  
Reply With Quote
Old 04-24-2011, 03:11 PM
  #247
Jason Arnold
 
Jason Arnold's Avatar
 
Join Date: Aug 2005
Location: Sydney, AUSTRALIA
Posts: 1,301
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Thanks Dave and Brenner. Looks like the weight isn't an issue....

How many mAh are you putting back into your pack after a P schedule?[&:]

Cheers,
Jason.
Jason Arnold is offline  
Reply With Quote
Old 04-24-2011, 03:47 PM
  #248
Brenner
Thread Starter
 
Join Date: Jul 2007
Location: Bridgman, MI
Posts: 721
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Hey Dave,

Unfortunately my finished rudder still looks just like my experimental rudder, because I've been too busy with Contra Drive stuff to find time to do any actual model airplane stuff. Fortunately however, I was really, really happy with the way my Integral was flying at the end of last season, so I'm hoping to be able start this season where I left off, except with more horizontal speed for days with high cross winds.

Brenner ...
Brenner is offline  
Reply With Quote
Old 04-24-2011, 04:12 PM
  #249
Dsnow
 
Join Date: Feb 2011
Location: Palatine, IL
Posts: 149
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Jason so far most of the flying and trim flights have been with the USA Masters sequence and only two with the P11 but all have been 8 minutes long, I can usually fly four +/- more passes before the timer sounds. The recharges have all been very consistent at 4100 +/- mah when using the two 22x20 props and 10.15:1 gear set but when using the 22x18 front and 22x20 back props the recharges have been 3750 +/- mah.

Dave
Dsnow is offline  
Reply With Quote
Old 04-25-2011, 04:37 AM
  #250
mups53
 
Join Date: Jan 2002
Location: Hoffman Estates, IL
Posts: 2,320
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Dave your plane is beautiful. Mine is ready to go and weather permitting maybe next saturday for the maiden.
I can see the advantage of your rudder and hopefully I'll be doing the same soon. Mike
mups53 is offline  
Reply With Quote
Reply


Thread Tools
Search this Thread
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -8. The time now is 06:35 AM.