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Contra Rotating Propeller Drive for f3a 2m Pattern Planes

Old 05-30-2014, 11:33 AM
  #1276  
 
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Flew my Oxai Hybird converted to Contradrive today.

Excellent first session and it looks like another viable Contra model to add to the list.

Malcolm
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Old 05-30-2014, 12:17 PM
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Looking good Malcolm !!
Clever touch up on the front end.
Details ???

Brian
Old 06-23-2014, 06:40 AM
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Hi,
A reoccurring theme starting to unfold.

Brian
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Old 06-23-2014, 03:23 PM
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Aerocompet Arixtra with Contra
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Old 07-15-2014, 12:14 AM
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Hi Brenner,
I noticed this on the equipment list for the European Champs , which are on right now. See pic below ;
Just to let you know !
There are just about 20 Contra set up there - that's 30% - and nearly all yours.
There are 2 or 3 Seba units, 1 Peter Hasse and the one in the pic - the rest are Brenner's

Brian
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Old 07-15-2014, 09:24 AM
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We estimate about 5/6 IC engines. So about 10%.
Old 08-20-2014, 05:23 AM
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Hi i'm Leonardo Scardigli from Italy, today I tried my ray bird with contradrive, fantastic! I'm really happy, I have to work on setting the brake, in some figures brakes so much.
My setup is hacker c50x13xl with 22x20rear and 22x18front







Best regards
Leonardo
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Old 08-20-2014, 05:31 AM
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I don't recall seeing posts comparing the 2 stiffness of Budd mounts.
I just got a chance to compare them subjectively on my BJ Craft Episode. I had started with the soft version and thought there might be too much motor movement allowed.
When I switched to the stiff version, I liked the more solid mount "feel". In the air at mid-to-hi power, the drive/plane sounded similar to how it did with the soft mounts. However, at low power and idle/brake, there was a relatively loud, low-frequency sound that had not been there before. I would guess that the soft version will do better on a sound meter, at least on this airframe.
Dan
Old 08-21-2014, 02:53 PM
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Hi all, I would like to ask you a help about the brake setting, can you tell me how to set it up to have a good brake. This is my setup:
dead time 0.0
brake initial 38%
brake final 50%
brake speed 0, 1s
I tried to raise it without improvement, perhaps I something wrong?


best regards
Leonardo
Old 08-22-2014, 12:33 AM
  #1285  
 
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Leonardos,

With my Neu motor setup otherwise identical to yours I have similar setup except have initial brake set to zero and. final brake only around 30% and this is more than enough. I think maybe you are not getting into final brake early enough and have final too high. Also check you are pulling the stick all the way back to the motor arming position or you won't go into brake. Similarly if you have set a low idle at bottom stick you get no braking, some people don't realise this.

Malcolm
Old 08-23-2014, 10:11 AM
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I tried to do other tests with small improvements, my model was already very fast with a single propeller, maybe I should try the 22 x 18 rear and fron to have the maximum of brake
Old 08-23-2014, 11:18 AM
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Leonardo,

What gear ratio are you running?

Malcolm
Old 08-23-2014, 11:23 AM
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Originally Posted by Malcolm H
Leonardo,

What gear ratio are you running?

Malcolm
hi Malcolm,

I have the gear ratio 10.33:1
Old 08-24-2014, 07:52 AM
  #1289  
 
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Leonardo,

The fact that you are running a high gear ratio should mean that when braking your motor is turning faster and you should get more retardation of the props for a given braking setting of your controller.

However the kV of your motor is 1249 and the kV of the Neu motor I am using is
1300. I am unsure what effect the lower kV has on the braking but I suspect it reduces it.

I run the 10.15:1 gear ratio and I would be very surprised if you could run an 18" pitch rear prop because already with your setup I believe you will need to run a higher throttle setting for cruise than you should need simply to get an acceptable cruise airspeed. I know you have said you have enough airspeed but I think if you increased the pitch of both props say 22" rear and 20" front or changed to the 10.15:1 ratio you would have better airspeed at a lower throttle setting.

I suggest you try running the higher pitch props or change ratio and then optimise your throttle curve for the new setup and then work on the braking. I think it may be that once you have a sensible cruise power/airspeed relationship your braking will improve too. Start with less brake maybe 20% and increase from there.

Hope this helps.
Malcolm
Old 08-24-2014, 02:32 PM
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I just came across this thread while doing some research on a Bugatti 100P Racer. Was that mentioned in any of these 52 pages???

Did your unit ever go into productions, and if so, where could I find it on the Internet???

Also, do the forward and aft props turn at the same RPM? Do they have the same Diameter/Pitch??

Thanks,

Bob
Old 08-24-2014, 08:49 PM
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f3aunlimited.com

click on the yellow contra banner.

Last edited by patternflyer1; 08-24-2014 at 08:55 PM. Reason: Forgot info
Old 08-24-2014, 10:31 PM
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Thanks!!

Bob
Old 08-25-2014, 02:06 AM
  #1293  
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Originally Posted by N1EDM
I just came across this thread while doing some research on a Bugatti 100P Racer. Was that mentioned in any of these 52 pages???

Did your unit ever go into productions, and if so, where could I find it on the Internet???

Also, do the forward and aft props turn at the same RPM? Do they have the same Diameter/Pitch??

Thanks,

Bob
http://www.contradrive.com/#!contact
or you can send a PM to Brenner via this thread

As mentioned by patternflyer1, you can buy everything from Mike at F3AUnlimited
Old 08-25-2014, 02:10 PM
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Malcolm,

Thanks for the advice, I do not know what to do, I would not spend more money with the risk of not solve the problem. I do not know if it depends very much on the model or from the propellers, but when they are flying in vertical descent, the brake is initially good but then the model is picking up speed, as if the brake was not constant until the end. Today I tried this setting:


dead time 0,6s
initial brake 36%
end brake 56%
speed brake 1,6s


but still I am not satisfied, I will continue to try hoping to find a good setting, Bruckmann flies with two 22x18 and flies really slow, but don't know his gear set. I would try the same propellers


best regards
Leonardo
Old 08-25-2014, 11:54 PM
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Leonardo,

Your timings are going to cause you problems. With the dead time set to 0.6 sec you will be well down a vertical before the brake even goes to initial setting. There is no reason to set "initial" to any value other than zero. Similarly with the brake speed set to 1.6s the model will have travelled a long way before the brake level increases to the final value. If you are not going to experiment with props or gear ratios I suggest you reduce the dead time to zero, the initial brake to zero and set the brake speed to the minimum setting you can. Then starting at zero increase the final brake in 5% increments until you find the best setting.

That is really all you can do.

Malcolm
Old 08-27-2014, 07:22 AM
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Hi,

I have finally got around to assembling a new model with the Brenner Contra-drive. There is a lot of material in this thread and trying to go through it all is a little overwhelming. I am looking for a setup summary of a well sorted setup which I can use to get me started. I will be using the following equipment..

1) CA Models DeJaVu
2) Brenner Contra drive (I have all the 20" and 22" props including the APC variants. I also have the complete range of gears)
3) Jetti Spin 99
4) Neu F3A
5) Futaba radio system

I am a little short on knowledge with electrics and the SPIN 99. Any setup advice with the Spin 99 would be great.
Can someone assist me with a good starting point based on the equipment I am using. I am currently flying F3A mainly the P schedule.
Old 08-28-2014, 12:36 AM
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Hi Peter,

I was hoping that someone else would step in here and offer some advice because I'm in danger of hogging this and the Allure thread with my opinions!

I will give you the same advice I gave Bryan Hebert. Start with the 10.15:1 gearset and the 22 x 20 rear, 22 x 18 front setup. This will give you the unique Contra "driving in low gear" experience which is very different to the average single prop setup. You can always prop up for more airspeed by going to the 20" pitch front prop and or going to the 9.84:1 gearset. I have also been trying the Brenner carbon APC clones in windy weather and like these too.

As for Spin settings, on my Neu I use:

Timing 5 deg
Frequency 8kHz
Acceleration minimum
Fixed end points
Auto extend from full throttle
Manual Brake - Dead time, minimum
Initial Brake 0%
Final brake 30%
Brake Speed, minimum

Sorry I can't remember the minimum settings from memory.

Hope this helps,

Malcolm
Old 08-28-2014, 12:45 AM
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Originally Posted by Malcolm H
Hi Peter,

I was hoping that someone else would step in here and offer some advice because I'm in danger of hogging this and the Allure thread with my opinions!

I will give you the same advice I gave Bryan Hebert. Start with the 10.15:1 gearset and the 22 x 20 rear, 22 x 18 front setup. This will give you the unique Contra "driving in low gear" experience which is very different to the average single prop setup. You can always prop up for more airspeed by going to the 20" pitch front prop and or going to the 9.84:1 gearset. I have also been trying the Brenner carbon APC clones in windy weather and like these too.

As for Spin settings, on my Neu I use:

Timing 5 deg
Frequency 8kHz
Acceleration minimum
Fixed end points
Auto extend from full throttle
Manual Brake - Dead time, minimum
Initial Brake 0%
Final brake 30%
Brake Speed, minimum

Sorry I can't remember the minimum settings from memory.

Hope this helps,

Malcolm
Hey Malcolm,

You're on the Contra thread not the Allure thread. ;-)

Been reading your info on the contra with great interest as with any luck I'll have one in the air by Christmas.

Cheers,
Jason.
Old 08-28-2014, 03:49 AM
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Yeh Jason,

Realised that but assumed most people keep an eye on anything remotely Contra related!

I guess you will be able to test fly wearing shorts at Christmas unlike some of us :-)

M
Old 08-29-2014, 04:51 AM
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Thanks Malcolm. That will help me get started. I hope to test fly next week.

Peter

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