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Author Topic: Counter Rotating Propellers for Stunt  (Read 5085 times)

Offline Matt Spencer

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Re: Counter Rotating Propellers for Stunt
« Reply #50 on: March 18, 2019, 05:53:25 PM »


Two high-density YASA electric motors are planned to provide the power for the P1e.

https://www.aerosociety.com/news/bright-sparks-the-quest-for-electric-speed/

Offline Matt Piatkowski

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Re: Counter Rotating Propellers for Stunt
« Reply #51 on: March 19, 2019, 07:18:11 AM »
Hi Matt,
It is always good to know what other people did and are doing.
Happy (electric) Flying,
Matt

Offline John Rist

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Re: Counter Rotating Propellers for Stunt
« Reply #52 on: March 19, 2019, 12:24:59 PM »


Two high-density YASA electric motors are planned to provide the power for the P1e.

https://www.aerosociety.com/news/bright-sparks-the-quest-for-electric-speed/

Now there's a candidate for an electric scale project.  Won't need a sound generator.
John Rist
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Offline Archie Adamisin

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Re: Counter Rotating Propellers for Stunt
« Reply #53 on: April 24, 2019, 07:01:16 PM »
What an interesting read.  Perhaps posting this pic and video are relevant.





Archie Adamisin
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Archie Adamisin
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Offline Steve Helmick

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Re: Counter Rotating Propellers for Stunt
« Reply #54 on: April 24, 2019, 08:12:17 PM »
It occurred to me to ask if having two props wouldn't make it more difficult to make the ideal 1 lap minimum glide for F2B competitions? But then, it's not always too easy to tell just when the power is definitely "off", since the prop on electrics typically windmills during the glide. Seems like the friction of the gear system would tend to stop the windmilling. A two motor counter rotating system sounds better than gears, but maybe higher weight. It would suck to be doing the OH8 when the gearbox suddenly went Tango Utah. 

Further, I recall somebody here writing that a windmilling propeller creates more drag than a stopped propeller, but I just don't see the logic of that. So glad I don't have to worry about this stuff!  y1 Steve
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Offline Matt Piatkowski

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Re: Counter Rotating Propellers for Stunt
« Reply #55 on: April 25, 2019, 07:25:15 AM »
Hi Archie,
Could you please provide some technical details regarding the contra system you are showing on youtube?
Specifically: the maximum continuous current, gear box ratio, weight and diameter and pitch of the props. used.

Thank you,
Matt Piatkowski

Offline T.J. Vieira

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Re: Counter Rotating Propellers for Stunt
« Reply #56 on: April 25, 2019, 08:50:01 AM »
there was a company at the Toledo show that had setups for this...

http://www.maxxprod.com/mpi/mpi-266.html


Offline TDM

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Re: Counter Rotating Propellers for Stunt
« Reply #57 on: April 25, 2019, 09:26:53 AM »
This subject really peaked my attention and looked over it and searched what is practical and what is not practical tried to see how could it be implemented and what are the benefits.
Starting with benefits By the looks of it No gyroscopic precession more laminar airflow behind the props.
Now for the practical side.
Two options: Firs is gear box drive and the second option two motors.
For the gear box the first thing that goes through my mind is something like this should work and is doable . For this one you must have some precision gears off the shelf preferably plus precision work to get it up and running. Several bearing must be used plus shafts that must fit props adapters special spinners in my book it translates to (it can be made but it is complex  heavy perhaps a little less than the weight of a second motor but you need a bigger motor to drive this whole mess the weight of the second prop,  weight+weight+weight+etc. did I mention weight?
For option two hack up two motors with some parts and go for it. This is the much simpler implementation it adds yet another motor another ESC, it is  pretty easy to make but you still have to mess with the spinner back-plate make some little parts for the motors assembly (no real issues here). But again did I mention weight of the second motor and ESC weight of the extra parts and this will be in the few ounces range.

This is the point where I always go back to some kind of aerodynamic device like the wing behind the canopy to clean up the air to the stab (tipping the scale at 10g maybe) and a Rabe Rudder setup (another 10g) both of which solve the same problems and are crazy much simpler to make and accessible to all. It can be fun to try counter rotating but for me I do not see the point my no BS thinking is saying that it is at best a novelty, o r i cant think about what otters are doing and how it can be implements. Maybe the guy at the wolds can tall us how he justifies and had implemented the concept. I am always want to accept new ideas and to things I don't see.
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Offline Matt Piatkowski

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Re: Counter Rotating Propellers for Stunt
« Reply #58 on: April 25, 2019, 01:47:59 PM »
Hi TDM,
shows exactly the straight (spur) gears and their configuration used in "Polish Contra". The latest gear box in this contra has helical gears and should be quieter but it is prohibitively expensive.

Hi Vieira,
The "two motors contras" (http://www.maxxprod.com) are very reasonably priced. CR3516-1030 system seems to be well suited for F2B but the extensive flight testing is needed to prove it.

Thank you,
Matt

Online Howard Rush

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Re: Counter Rotating Propellers for Stunt
« Reply #59 on: April 25, 2019, 03:56:52 PM »
The latest gear box in this contra has helical gears and should be quieter but it is prohibitively expensive.

Expense does not prohibit the Jive Combat Team.
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Online Howard Rush

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Re: Counter Rotating Propellers for Stunt
« Reply #60 on: April 25, 2019, 04:01:16 PM »
Archie,

Regarding video 78597:  You can't hand start it.  It's electric, and that's not how you start them.

Hope this helps.
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Offline Archie Adamisin

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Re: Counter Rotating Propellers for Stunt
« Reply #61 on: April 28, 2019, 10:04:11 AM »
Hi Archie,
Could you please provide some technical details regarding the contra system you are showing on youtube?
Specifically: the maximum continuous current, gear box ratio, weight and diameter and pitch of the props. used.

Thank you,
Matt Piatkowski

Matt,
 
Max continuous current is 50 amps.
Gear ratio 1:1
Weight as shown with props and spinners 10.5 oz.
Front propeller 10 x 5 APC
Rear propellor 10 x 5.8 Pusher APC

Archie Adamisin
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Offline Archie Adamisin

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Re: Counter Rotating Propellers for Stunt
« Reply #62 on: April 28, 2019, 10:06:09 AM »
Archie,

Regarding video 78597:  You can't hand start it.  It's electric, and that's not how you start them.

Hope this helps.

Howard,

Maybe if I found that glow igniter.  Dang, that's where  I screwed up.  Or I could have pushed the magic red button.  That always goes well.

Archie Adamisin
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Offline Archie Adamisin

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Re: Counter Rotating Propellers for Stunt
« Reply #63 on: April 28, 2019, 10:13:24 AM »
Hi TDM,
shows exactly the straight (spur) gears and their configuration used in "Polish Contra". The latest gear box in this contra has helical gears and should be quieter but it is prohibitively expensive.

Hi Vieira,
The "two motors contras" (http://www.maxxprod.com) are very reasonably priced. CR3516-1030 system seems to be well suited for F2B but the extensive flight testing is needed to prove it.

Thank you,
Matt

I think the concept of this Himax is great.  I have one.  It is a 3S setup.  It is a monstrous pull system.  I'm pretty sure my bench moved when I ran mine on the supplies props.  Need a big 3S pack.

Archie Adamisin
Archie Adamisin
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Offline Matt Brown

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Re: Counter Rotating Propellers for Stunt
« Reply #64 on: May 01, 2019, 03:30:14 PM »
This thread got me thinking and looking on EBay. I ran across this unit and thought a smaller one could be built relatively easy compared to the polish unit. I like the simplicity of the gear/belt arrangement too.

Matt

Offline Chris Wilson

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Re: Counter Rotating Propellers for Stunt
« Reply #65 on: May 01, 2019, 11:18:17 PM »
I would like to see if counter rotation improve ducted fans enough to be viable.

In theory it should.
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Offline Matt Piatkowski

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Re: Counter Rotating Propellers for Stunt
« Reply #66 on: May 15, 2019, 12:13:00 AM »
Hello everybody,
The first of the two Himax CR3516-1030 systems has been flight tested by one of my colleagues in Poland without me being present. The system used two Spin66 ESC, one Igor's active timer and 3S 4000 mAh battery. 12x6 carbon composite two blade propellers were used. The RTF weight of the model was 2025 grams (71.5 oz.), wings span = 60" and the wings surface area with flaps = 690 in^2. The lines length = 64', eye-to-eye.

The tests were done in a hurry, without bothering to check the ground current and, unfortunately, one of the motors was burned in flight. The motors were mailed to the guy who specializes in rewinding and rewinded with thinner copper wire to get the Kv=500. I saw three flights using these motors and 6S 2700 mAh. Zippy battery. The ESC, timer and props were the same. This time the tests were successful and the quality of the pattern maneuvers - exceptional. Judging from the battery use after landing, the average in-flight current in each motor, with the ESC connected PARALLEL was no more than 13 Amps. The total average in-flight power was, therefore, about 625 Watts (2x13Ax24V). This calculation assumes the average voltage of the 6S battery to be 24 Volts. 625 Watts converts to 8-9 Watts/oz. in this model. Because every contra system generates more thrust in the direction of flight than a single prop systems, the plane, weighting 71.5 oz., flew easily every maneuver with exceptional stability.

More flight tests are planned in the next two weeks.

Regards,
M

Online Brett Buck

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Re: Counter Rotating Propellers for Stunt
« Reply #67 on: May 15, 2019, 09:01:28 PM »
l. Because every contra system generates more thrust in the direction of flight than a single prop systems,

  Huh?

    Brett

Offline Paul Walker

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Re: Counter Rotating Propellers for Stunt
« Reply #68 on: May 15, 2019, 10:36:13 PM »
Because every contra system generates more thrust in the direction of flight than a single prop
Regards,
M
[/quote]

If it generates MORE thrust, wouldn't it fly faster thus requiring you to reduce the thrust to fly slower????

Offline Matt Piatkowski

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Re: Counter Rotating Propellers for Stunt
« Reply #69 on: May 16, 2019, 02:31:47 AM »
Yes, Paul. The plane with contra can fly slower than the plane with a single prop and still will have enough speed for the overhead maneuvers.
Reducing the thrust reduces the current and this is the Holy Grail of the entire exercise. Less current, less battery drain. Less battery drain - smaller capacity battery can be used. Smaller capacity - lighter battery.

Best Regards,
M

Online Brett Buck

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Re: Counter Rotating Propellers for Stunt
« Reply #70 on: May 16, 2019, 04:15:43 AM »
Yes, Paul. The plane with contra can fly slower than the plane with a single prop and still will have enough speed for the overhead maneuvers.
Reducing the thrust reduces the current and this is the Holy Grail of the entire exercise. Less current, less battery drain. Less battery drain - smaller capacity battery can be used. Smaller capacity - lighter battery.


   I thought you said it *increased* the thrust - now it is *decreasing* the thrust?  And all to accomplish a small weight reduction in the battery? This weight reduction in the battery exceeds the additional weight of the gearbox or concentric shafts? And this is somehow the Holy Grail?

   I think you need to show math, and the numbers, because I am having a hard time understanding what you are saying.

      Brett

Offline Matt Piatkowski

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Re: Counter Rotating Propellers for Stunt
« Reply #71 on: May 22, 2019, 01:58:47 AM »
Hello everybody,
The plane with Himax 3516-500 received new propellers and it is flying even better than before.

The propellers used previously were identical to https://www.graupner.com/E-PROP-30x15-cm-12X6-Zoll/1326.12X6/.

The launch RPM. (governed by the Target Throttle parameter of Igor's active timer) were 9,500 with the above mentioned props. and this was not enough for the props to work efficiently. These props., having thin and very narrow blades and the "profile bump" close to the hub, work the best at much higher RPM.

The propellers used now are 12x6 E carbon composite, similar in shape to 12x6 E APC and have wider blades and another distribution of the blades curvature. With these props., the launch RPM are 9,300 and the battery drain after 5 minutes 10 seconds pattern increased only marginally. The person flying the plane is an average F2B flier but, by using contra, he improved the quality and consistency of all maneuvers.

Please expect more reports from the field and also my report from the Polish F2B Championship in Wloclawek, May 31- June 02, 2019. I will also talk to the organizers of the next year World F2B Championship in Wloclawek. Happy (F2B) Flying. Matt

Offline TDM

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Re: Counter Rotating Propellers for Stunt
« Reply #72 on: May 22, 2019, 08:26:46 AM »
This subject peaked my interest for a while, but I think I am dropping the idea. This is why I think is not the best approach. The thing is the intent of the system and what it tries to address. It addresses gyroscopic precession and cleans the air behind the prop. So far there are two approaches here: one with two motors hacked together or add a complex gear box. On one side you add another motor another ESC plus extra battery to drive it, and on the other side you add a gear box and up the power from the motor that has to spin 2 props in which case you again add motor and more battery. Either way you are looking at minimum a few good ounces in the nose and some more on the battery, and it is extra weight that I don't think we can afford. This is the point where I keep going back to: if I have a gyroscopic precession problem cant I just fix that with a Rabe rudder and pay 10-20g extra weight and achieve the same thing? As for cleaning up the air some fins (like barge boards in a F1 car) that stabilize the airflow and pay 15g for that sounds like a more sensible much easier way to address that issue.
I understand the idea is coming from the pattern fliers but look at their application. There are two disciplines: the big guise , and the indoor guise. The big guise can care less for a few ounces in the nose, now the indoor fliers who care for the weight run super low rpm and don't care for supporting the shaft with bearings etc, they also only use a crude simple super light no gear setup and I bet they change some parts all the time. In our application my best guesstimate is we run as low as 6500 to as high as 11000 and we have to account for the longevity of the system, and here is where the practical doesn't add up for me. Every time I look in to making a light gear box and start to add bearings shafts special whatever and the weight adds up I keep going back to simple Rabe rudder and fins simple light and practical.
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Offline Matt Piatkowski

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Re: Counter Rotating Propellers for Stunt
« Reply #73 on: May 22, 2019, 10:29:23 AM »
Hi TDM,
There are currently six F2B fliers in Poland using contras. Four of them use a single motor and the gear box and two use contras based on two motors in tandem (Himax 3516-500 and the custom build system based on two AXI motors).

It is a matter of personal choice to use or not to use the counter-rotating propellers system for F2B but I can tell you what I heard from a very good F2B flier who represents Poland internationally: "once you try contra in F2B, you will never go back to the traditional system".

Happy Flying,
M


 

Online Ken Culbertson

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Re: Counter Rotating Propellers for Stunt
« Reply #74 on: May 22, 2019, 12:09:37 PM »
Hi TDM,
There are currently six F2B fliers in Poland using contras. Four of them use a single motor and the gear box and two use contras based on two motors in tandem (Himax 3516-500 and the custom build system based on two AXI motors).

It is a matter of personal choice to use or not to use the counter-rotating propellers system for F2B but I can tell you what I heard from a very good F2B flier who represents Poland internationally: "once you try contra in F2B, you will never go back to the traditional system".

Happy Flying,
M
What scares me is that as technology improves two things happen.  First, all but a few extremely talented fliers are forced out of the competition and the talent starts to lessen.  Soon it is the team with the most $$$ to outfit their fliers that wins.  That will never happen in the USA unless some billionair's kid decides to fly and he/she is good enough to make the team.  The Polish team is going to be equipped.  I can assume the Chinese will have them as soon as they can steal one.  The cost of a properly equipped F2B ship is now what -$3,000 to $4,000?  Where does it end and for that matter, why should it.  I am realistic enough to know that my days for making the US team are far in my rear view mirror but it is my chosen avocation .  I want our team to win but even the best driver in the world cannot win a Grand Prix in a go-kart.

I am sure that this is not the last technological improvement we will see.  With the coming of electric power comes electronic control.  I am pretty sure it won't be long before we have electronic judging and except for some rules, what is to prevent electronic control dampers for example.  Altitude 5', autopilot on... 

I am fascinated by what you are doing and would love to have one for myself but for what it is worth, I am with TDM on this one.

Ken

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Online Howard Rush

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Re: Counter Rotating Propellers for Stunt
« Reply #75 on: May 22, 2019, 04:09:04 PM »
I donít think this is the technology you need to worry about. Vortex generators are the big threat.
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Online pmackenzie

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Re: Counter Rotating Propellers for Stunt
« Reply #76 on: May 22, 2019, 05:36:01 PM »
now the indoor fliers who care for the weight run super low rpm and don't care for supporting the shaft with bearings etc, they also only use a crude simple super light no gear setup and I bet they change some parts all the time. I

In the Glavak F3P contra all shafts are supported by ball bearings.
The design is far from "crude". Elegant is the word that comes to my mind.

Other than the first belts that were just Buna O-rings I have never had to change any components.
They replaced all O rings belts with ones machined ( turned on a lathe) from Urethane for free. These ones have never failed.

Power level is orders of magnitude less than what you need for F2B ( 5 watts versus 500 watts), but the design is highly refined for the intended purpose.

Having said that, the cost that the contra adds to the entry to F3P is high. And once every one has them the advantage over your competitor vanishes.

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Online Ken Culbertson

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Re: Counter Rotating Propellers for Stunt
« Reply #77 on: May 22, 2019, 06:07:13 PM »
In the Glavak F3P contra all shafts are supported by ball bearings.
The design is far from "crude". Elegant is the word that comes to my mind.

Other than the first belts that were just Buna O-rings I have never had to change any components.
They replaced all O rings belts with ones machined ( turned on a lathe) from Urethane for free. These ones have never failed.

Power level is orders of magnitude less than what you need for F2B ( 5 watts versus 500 watts), but the design is highly refined for the intended purpose.

Having said that, the cost that the contra adds to the entry to F3P is high. And once every one has them the advantage over your competitor vanishes.

Pat MacKenzie
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Offline Matt Piatkowski

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Re: Counter Rotating Propellers for Stunt
« Reply #78 on: May 24, 2019, 05:48:06 AM »
Hello Everybody,
The issue of price of the plane v/s its pattern performance is the centerpiece of this thread.
The Himax 3516-1030 contra system with two APC propellers costs $299 USD plus shipping when shipped within the continental US.

I bought two such systems from the warehouse in the Chicago area while being still in Toronto, Canada and the total cost was about $800 USD. This included the shipment, Canadian Custom dues, processing fees (whatever this means...) and the Canadian taxes. Each system cost me, therefore, about $ 400 USD.

If I buy such system now, sitting in the central Poland and surrounded by acres of trees and meadows, the cost will climb to about 475-490 USD per one. The main difference? Shipping costs by Fedex from Chicago to Warsaw, Poland.

Because the system will be coming from the outside of the EU, I will pay the custom dues and taxes in Poland but these are not much different than in Canada.

Consequently, everybody in the F2B community in the EU can have Himax 3516-1030 for about $500 USD or 445 Euros. This, I believe, is a very reasonable price for something that will make you a better Pattern flier.

Himax 3516-1030 can be used for the full size F2B model if the max. current is kept below 35 Amps. When I run the tests myself with my 3516-1030, I will not use the RPM boost (and the current boost), provided by the Igor's active timer sensitivity parameter set at 55-65 - I will use 0.0. More to come - my friend is waiting for me now and we will fly together. M

Offline Matt Piatkowski

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Re: Counter Rotating Propellers for Stunt
« Reply #79 on: May 29, 2019, 04:57:40 AM »
Hello everybody,

Please see the attachments. These are new F2B "Contra" planes built by Sylwester Kubik and Tomasz Jadczak. They both live in the area and I frequently fly with them on grass. Sylwester's plane uses the geared system and a single motor, Tomek's plane uses the Himax system with two counter rotating motors, rewinded from from Kv=1030 to Kv=500. Both models fly very well using the 6S batteries, with exceptional stability and almost constant speed in maneuvers. Sylwester's contra system is about 75 grams (2.6 oz.) lighter because it uses one Spin66 ESC, Tomek's contra system is heavier because it uses two Spin66 ESC and extended leads, soldered in parallel. Tomek's plane weights, RTF, about 1870 grams (66 oz.), Sylwester's plane - 1795 grams (63.3 oz.). Lap times: Sylwester's plane - 5.2-5.3 sec., Tomek's plane -5.4 sec. We all use the lines length = 19.40 m. (64') eye-to-eye.

My single motor Big Red weights now RTF 1845 grams and flies 5.1 sec. laps. I have asked Tomek to rebuild and reinforce the front of the fuselage with the carbon composite multi-directional fabric and changed the motor from Plettenberg 15-22 to MVVS 8.0. Rebuilding added 18 grams (0.63 oz. ) and MVVS 8.0 is 1.0 oz. heavier than Pletty.

I have asked the Plettenberg Factory to exchange the shaft in the Pletty powering Big Red. The new shaft will be without fan and the weight of the motor will be 188-190 grams (6.7 oz. ) instead 201 grams (7.09 oz.) with the cooling fan.

Big Red with MVVS 8.0 flies well but after the motor change back to Plettenberg 15-22 without fan, it will fly better for sure. 1.0 oz. less at the nose makes difference - in terms of the absolute weight and the pitching moment of inertia. The comparison of my plane with the planes using contra, show that the contra planes fly slower and still maintain enough power to climb and in the OH maneuvers.

More to come. We are leaving for Wloclawek tomorrow.

Happy Flying,
M

Offline Matt Spencer

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Re: Counter Rotating Propellers for Stunt
« Reply #80 on: May 29, 2019, 06:13:42 AM »
All is Not Lost ! .



This is more likely the most efficent system for F2B .  VD~ S?P Igor could do a Yam sensitive cross feed electro wizard box , for multis . To keep em straight n square to the lines .

Though I admit Ive not yet figured what order the contra props'd go on a four engined job yet .  >:( ;D

The Olde ' assisted airflow ' over the flaps , being somewhat advantageous .
Coiuld even use the scale L E intake / outlet set up to advantage , seeing it wont become oil soaked .
And if anyones whingeing about the CABLE WEIGHT , use the steel for spars .  :-X

Or look at a Brabazon , its not far off the corect proportions , or wing depth . sortoff a super duper Constellation .  :P



Even got our straight T E , swept L E set up .  :-\ So wouldnt be entirely impossable. Generally when people write rules , they accomodate atstounding machineary . :-\
Or do they ?  Such as 80 in. span B-17s .
Not sure why thats not gone electric . One does wonder . If you want something truly awful , look at the SARO Princess flying boat . Same set up as the Brab. .

https://proxy.duckduckgo.com/iu/?u=https%3A%2F%2Fwww.flightsim.com%2Fvbfs%2Fattachment.php%3Fattachmentid%3D102047%26stc%3D1%26thumb%3D1%26d%3D1335733723&f=1

The Pond Racer set up'd do it too . Someone there ( U.S. ) has already had a go there .

 n1 Chin Up . chop chop .  H^^

Offline Matt Spencer

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Re: Counter Rotating Propellers for Stunt
« Reply #81 on: May 29, 2019, 06:20:54 AM »
This suckers got good proportions too . And was Faster / more efficent , one motor , on the REAR injun/prop ! We wont metion the D-23 & Two Much layout. For Now . Hop to it lads .



First contra - props at a World Champs ? ( might not be Co-Axial , but definately Contra Rotating ! ) .go to 4:25 here

« Last Edit: May 29, 2019, 07:02:37 AM by Matt Spencer »

Offline Matt Piatkowski

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Re: Counter Rotating Propellers for Stunt
« Reply #82 on: May 29, 2019, 06:23:51 AM »
Photo of my Big Red after face lift.

Offline Matt Piatkowski

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Re: Counter Rotating Propellers for Stunt
« Reply #83 on: July 22, 2019, 11:09:15 PM »
Hello,
I have received Himax CR3516-1030 counter-rotating propellers system for testing.

http://Http://www.maxxprod.com/mpi/mpi-266.html shows this system with 12x6 and 11x8 APC propellers for use with the 3S battery. It is stated in CR3516.pdf (attached) that "Efficient Operating Current =30-36 A per rotor, 40A Max 15 seconds per rotor".

I would like to test this system properly to avoid burning the windings (ref: my message in this thread on May 24, 2019, 05:48:06 AM).

I have found that both motors have 16AWG insulated braided copper leads.

Let's start from this finding. Will 16AWG braided copper leads survive 30 Amps. per motor supplied by the ESC as alternating current? The web available data in this regard is inconclusive.

Thank you and Happy Electric Flying.
M

P.S: I am also starting the brand new thread regarding Himax CR3516-XXXX on gettin-all-amp'ed-up!




   




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