Contra Rotating Propeller Drive for f3a 2m Pattern Planes
06-13-2013, 11:46 AM
#1152
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RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
Tony, I already have fences on my plane. I'd like to add something.
Here is a pic of an extra bottom area on my Integral.
Vincent ...
Here is a pic of an extra bottom area on my Integral.
Vincent ...
06-14-2013, 05:55 AM
#1153
RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
Hi Tony,
What size fences are you currently using and are they parallel to the centre line or toe in ?
Brian
What size fences are you currently using and are they parallel to the centre line or toe in ?
Brian
06-14-2013, 01:45 PM
#1154
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Location: Rosamond, CA
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RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
I am running two fences on each stab half. The outside one is the stock fence that comes with the kit. The inside one is one I made that is slightly larger then the stock fence. They are mounted parallel to the centerline of the model.
I'll try to attach a pic that might help.
I'll try to attach a pic that might help.
06-17-2013, 01:44 PM
#1156
Join Date: Aug 2005
Location: Sydney, AUSTRALIA
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RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
Hi Guys,
Looks like someone else is trying the Contra Drive.
No stab fences by the looks of it.
Cheers,
Jason.
Looks like someone else is trying the Contra Drive.
No stab fences by the looks of it.
Cheers,
Jason.
06-19-2013, 06:13 AM
#1160
Thread Starter
RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
ORIGINAL: bem
Hi,
Is that Andrew Jesky's planes?
/Bo
Hi,
Is that Andrew Jesky's planes?
/Bo
Brenner ...
06-19-2013, 11:54 PM
#1161
RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
ORIGINAL: Brenner
That's Gernot Bruckman in Moravia..
That's Gernot Bruckman in Moravia..
Jim O
06-23-2013, 09:29 AM
#1163
Thread Starter
RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
I have heard that some pilots would like to know what is the best throttle curve to use with a Contra Drive.
This is the throttle curve that I have been using, and I am finding that it is very linear.
However, on my ESC I am also using auto endpoints for low throttle, and fixed endpoints for high throttle, and at high throttle I am using 2.05ms for the pulse width setting. This gives me fine throttle control in the upper 25% of the high throttle stick position.
In addition to this I am also using soft acceleration (>=1 second..) and about 35% ESC braking. I am also applying the braking over about 1 second as well. Other than this I am setting the ESC for "Normal" operation.
Brenner ...
This is the throttle curve that I have been using, and I am finding that it is very linear.
However, on my ESC I am also using auto endpoints for low throttle, and fixed endpoints for high throttle, and at high throttle I am using 2.05ms for the pulse width setting. This gives me fine throttle control in the upper 25% of the high throttle stick position.
In addition to this I am also using soft acceleration (>=1 second..) and about 35% ESC braking. I am also applying the braking over about 1 second as well. Other than this I am setting the ESC for "Normal" operation.
Brenner ...
06-24-2013, 09:31 AM
#1164
My Feedback: (34)
RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
ORIGINAL: Jason Arnold
Hi Guys,
Looks like someone else is trying the Contra Drive.
No stab fences by the looks of it.
Cheers,
Jason.
Hi Guys,
Looks like someone else is trying the Contra Drive.
No stab fences by the looks of it.
Cheers,
Jason.
06-24-2013, 10:43 AM
#1165
RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
ORIGINAL: PeterP
Looks like another world class flyer who recently won a world cup event is using a contra
Looks like another world class flyer who recently won a world cup event is using a contra
[img][/img]
06-30-2013, 02:08 PM
#1166
RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
Thought I'd share this pic of the Contra models at this weekend's Triple Crown Home International Championship between England Ireland and Scotland. Team Ireland were victorious with two Contra operators in the team Brian Carolan (Mid Rex Bipe) and Nial O'Sullivan (Asyuler).
Highest individual Contra operator was Steve Burgess, Scotland also flying an Asyuler.
Malcolm
Highest individual Contra operator was Steve Burgess, Scotland also flying an Asyuler.
Malcolm
06-30-2013, 03:49 PM
#1167
My Feedback: (1)
RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
Hi,
Up here in the north it was this week Nordic Championship in classs FAI F3A (P-13, F-13) and Nordic (N-13) and out of 27 competitors two had contra drives (Brenner's contra drive).
It was one Finnish guy with Wind S Pro and one Danish guy with Angels Shadow that flew withcontra drives. I was competing there myself so I saw both planes on ground and in the air.
/Bo
Up here in the north it was this week Nordic Championship in classs FAI F3A (P-13, F-13) and Nordic (N-13) and out of 27 competitors two had contra drives (Brenner's contra drive).
It was one Finnish guy with Wind S Pro and one Danish guy with Angels Shadow that flew withcontra drives. I was competing there myself so I saw both planes on ground and in the air.
/Bo
07-01-2013, 04:18 AM
#1168
Thread Starter
RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
ORIGINAL: Brenner
I have heard that some pilots would like to know what is the best throttle curve to use with a Contra Drive.
This is the throttle curve that I have been using, and I am finding that it is very linear.
However, on my ESC I am also using auto endpoints for low throttle, and fixed endpoints for high throttle, and at high throttle I am using 2.05ms for the pulse width setting. This gives me fine throttle control in the upper 25% of the high throttle stick position.
In addition to this I am also using soft acceleration (>=1 second..) and about 35% ESC braking. I am also applying the braking over about 1 second as well. Other than this I am setting the ESC for ''Normal'' operation.
Brenner ...
I have heard that some pilots would like to know what is the best throttle curve to use with a Contra Drive.
This is the throttle curve that I have been using, and I am finding that it is very linear.
However, on my ESC I am also using auto endpoints for low throttle, and fixed endpoints for high throttle, and at high throttle I am using 2.05ms for the pulse width setting. This gives me fine throttle control in the upper 25% of the high throttle stick position.
In addition to this I am also using soft acceleration (>=1 second..) and about 35% ESC braking. I am also applying the braking over about 1 second as well. Other than this I am setting the ESC for ''Normal'' operation.
Brenner ...
Now I'm using a 1.95ms pulse width timing for full throttle. 2.05ms worked well, but this has the effect of making the ESC cut the throttle back a little at full stick, and 1.95ms gives me access to full throttle if I need it.
Brenner ...
07-01-2013, 04:21 AM
#1169
Thread Starter
RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
Hey Malcolm,
Thanks for posting the picture. As far as I know, six Contras at one contest is the current record.
Were there any Seba Contra Drives at the Contest?
Brenner ...
Thanks for posting the picture. As far as I know, six Contras at one contest is the current record.
Were there any Seba Contra Drives at the Contest?
Brenner ...
07-01-2013, 04:29 AM
#1170
RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
Hi Brenner,
No I haven't seen any Seba drives being used in this part of the world other than by Seba himself and another San Marino guy at a FAI World Cup Event in the England last year.
Why would there be? No one gives service and backup like you do!
Malcolm
No I haven't seen any Seba drives being used in this part of the world other than by Seba himself and another San Marino guy at a FAI World Cup Event in the England last year.
Why would there be? No one gives service and backup like you do!
Malcolm
07-02-2013, 03:56 AM
#1172
RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
Hi Brenner,
OK I have been waiting for someone else to ask this so that I'm not the one that looks stupid but I guess its down to me to ask!
Over on the Episode thread you stated in respect to Contradrive installations that:
"Zero degrees of right thrust. (This is important. We have found that a difference as small as 20g in weight between front and rear props can create the need for rudder trim..)"
Can you elaborate please?
Malcolm
OK I have been waiting for someone else to ask this so that I'm not the one that looks stupid but I guess its down to me to ask!
Over on the Episode thread you stated in respect to Contradrive installations that:
"Zero degrees of right thrust. (This is important. We have found that a difference as small as 20g in weight between front and rear props can create the need for rudder trim..)"
Can you elaborate please?
Malcolm
07-02-2013, 04:22 AM
#1173
Thread Starter
RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
Hey Malcolm,
Just recently Dave Snow reported that he had been experimenting with his setup by mixing various props, and he had an old prop from several years ago that weighed about 20g more than our current props, and when he used this prop with one of our current props, he found that he had to add rudder trim trim to compensate for the difference in prop weight.
He also ran the same setup with two of our recent props and in this case he didn't have to add rudder trim, so he feels pretty confident that the trim was needed to compensate for the heavy prop.
So, the takeaway here is that the front and rear props need to weigh about the same, or rudder trim/right thrust might be needed.
Brenner ...
Just recently Dave Snow reported that he had been experimenting with his setup by mixing various props, and he had an old prop from several years ago that weighed about 20g more than our current props, and when he used this prop with one of our current props, he found that he had to add rudder trim trim to compensate for the difference in prop weight.
He also ran the same setup with two of our recent props and in this case he didn't have to add rudder trim, so he feels pretty confident that the trim was needed to compensate for the heavy prop.
So, the takeaway here is that the front and rear props need to weigh about the same, or rudder trim/right thrust might be needed.
Brenner ...
07-02-2013, 04:45 AM
#1174
RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
Very interesting Brenner,
So is this a steady state trim condition or one exhibited during a push or pull? I'm going out on a limb here and would hypothesize that this is an aerodynamic effect caused by a difference in shape or stiffness associated with the change in weight rather than the weight itself.
I say this based on the early posts in this thread re gyroscopic effects where we discounted gyroscopic forces of two opposite spinning props. It will be really interesting to see what the real theorists have to say!
Malcolm
So is this a steady state trim condition or one exhibited during a push or pull? I'm going out on a limb here and would hypothesize that this is an aerodynamic effect caused by a difference in shape or stiffness associated with the change in weight rather than the weight itself.
I say this based on the early posts in this thread re gyroscopic effects where we discounted gyroscopic forces of two opposite spinning props. It will be really interesting to see what the real theorists have to say!
Malcolm
07-02-2013, 05:08 AM
#1175
Thread Starter
RE: Contra Rotating Propeller Drive for f3a 2m Pattern Planes
I am going to have to defer to Dave wth regard to the details concerning what he observed, because this is an experiment that I haven't tried myself.
However, like you say, I think that prop weight is primarily going to affect gyroscopic moment, so this suggests that what Dave is seeing must be a gyroscopic effect.
Brenner ...
However, like you say, I think that prop weight is primarily going to affect gyroscopic moment, so this suggests that what Dave is seeing must be a gyroscopic effect.
Brenner ...