Shop our Airplanes Products Drone Products Sales
Thread Tools
Jun 30, 2008, 11:26 AM
Registered User
chrisgood's Avatar
Discussion

Counter-Rotating NightOwl Knockoff


In this thread: https://www.rcgroups.com/forums/showthread.php?t=517997

kram242 presents his comBAT plane, and I have had lots of fun with that design. He also has a flying trashcan on his website called the NightOwl, and I built a few of those, using his pictures as a guide.

I took my big single engine NightOwl and converted it to counter-rotating props on two Himax motors with gears. This was a testbed for the new version. Roll was mixed into the motors, so when I command right roll, the clockwise motor turned faster and the counter-clockwise motor turned slower, and vice-versa. It had elevons on the horizontal surfaces, and one servo for the vertical / rudder surface, for three surfaces total. Video of that version can be seen here:

https://www.rcgroups.com/forums/show...9#post10034535

In the videos at the above post, the testbed had wood props, but I now have the right size electric props. I have rebuilt it lighter with the new props, and it has four separate surfaces. The two vertical surfaces are mixed together for rudder, and the two horizontal surfaces are mixed for elevator. All four surfaces are mixed for roll, plus the motors are mixed into roll like they were for the original testbed. I just finished it last night, and only have a few minutes of flight, but the new version is great!

The mixing in my JR 7202 is set up:

Motor 1 = throttle (channel 1)
Left Horizontal surface = aileron (channel 2)
Right Horizontal surface = elevator (channel 3)
Top Vertical surface = rudder (channel 4)
Motor 2 = gear (channel 5)
Bottom Vertical surface = flaps (channel 6)

flaps : inhibit
gear ATV : 0%
elevon mix : ON (roll + pitch --> horizontal surfaces)
rud ATV: 75% (elevon mixing is 75%, so this makes the rud mix the same)
Pmix 1: Thr --> Gear 100% (motor 1 + motor 2 together)
Pmix 2: Rud --> Flaps 100% (top rudder + bottom rudder together)
Pmix 3: Ail --> Rud -75% (roll --> top rudder)
Pmix 4: Ail --> Flap -75% (roll --> bottom rudder)
Pmix 5: Ail --> Thr +25% (roll --> motor 1 +)
Pmix 6: Ail --> Gear -25% (roll --> motor 2 -)

I need to add expo to the controls, and will post video of the new version later.

Chris
Sign up now
to remove ads between posts
Jun 30, 2008, 11:36 AM
Sopwith Camel's Cousin
Quote:
Originally Posted by chrisgood
In this thread: ...
I took my big single engine NightOwl and converted it to counter-rotating props on two Himax motors with gears. This was a testbed for the new version. Roll was mixed into the motors, so when I command right roll, the clockwise motor turned faster and the counter-clockwise motor turned slower, and vice-versa. ...
This part resembles co-axial helicopters (multi-rotor helicopter forum) like Esky lama3 and Blade Cx, which have 2 counter-rotating rotors, and their yaw (rotation about the prop/rotor shaft axis, so like a plane's roll) is controlled by turning one motor faster than the other.
Jun 30, 2008, 12:38 PM
-+- PhlatBoyz -+-
kram242's Avatar

Now you can built this!


Nice!.. Got me thinking with your setup you could build this!
Mark
Jul 01, 2008, 07:58 PM
Registered User
chrisgood's Avatar
I have the first video of the new version. This was a quick test flight tonight. The roll rate is unbelievable with all four surfaces deflected, but it s also a bit less stable in forward flight than the previous version. Practice, practice ...

Counter Rotating Blades NightOwl #4 (1 min 9 sec)


Chris
Jul 01, 2008, 09:54 PM
Registered User
Or the SNECMA C450 Coleoptere. That type of airplane has what is called an annular wing. An annular wing is a closed wing, usually a circle. I've wanted to build one for a while. I thought I'd be first but someone beat me to it.

Although I suppose it isn't a complete annular wing. It's more of a hybrid.
Jul 16, 2008, 08:04 PM
Registered User
chrisgood's Avatar
New video from last night! I am starting to get the hang of this thing.

Counter Rotating Ducted Fan NightOwl #5 (2 min 3 sec)
Sep 10, 2008, 09:17 PM
Registered User
chrisgood's Avatar
Here a couple shots of it in flight.

Chris
Sep 10, 2008, 09:34 PM
"Hobby Apparatus" Flyer
Mikey C.'s Avatar
That looks really interesting. Is it fun to fly, or more of a stress-fest?
Sep 11, 2008, 01:04 PM
Registered User
Pavelow's Avatar
I'm going to try to duplicate this, but just having control surface roll control. I would get dizzy trying to duplicate your roll rate. I don't know how you can keep orientated. I plan to have counter-rotating engines, slaved to a single speed controller. I would like to get some idea of where you put the Center of Gravity at. Also, basic height and weight would be helpful.
Sep 11, 2008, 01:39 PM
"It's a Quad" :O
thewz's Avatar
Question: Which side is the top

Answer: Yes

Great Scott man.....how do you know which way it's going to go when you are in forward flight?
Sep 11, 2008, 03:23 PM
SG Talon... Super Genius.
Someone built that Wespe already Kram. I think it was in the Ducted Fan section i think.

His was very scale though. I would never make something that scale.
Sep 11, 2008, 04:13 PM
Registered User
Put 20 in the air and launch an Estes rocket at them and you have a game of Space Invaders!!
Sep 11, 2008, 08:21 PM
Registered User

Very Cool


Boy ChrisG, you must be an avionics genius to have come up with this thing. It would be very cool if you could get hold of an IMU and put it in that thing.
Sep 13, 2008, 12:10 PM
Registered User
chrisgood's Avatar
Its actually not that bad; perhaps a bit harder to fly than a chopper. Several people in my club have flown it for varying lengths of time and success, with one person who was able to get it pretty quickly.

One of the fins is painted black, and that is the top surface in forward flight. When it goes into the fast roll, I just point it up and completely lose track of orientation until I remove the roll command, then input full up elevator and it loops tightly back to nose-up attitude.

The main carbon rods are .75 meters long, so that should give a good starting point for size. I use four Futaba S-133 servos for the surfaces, and two identical 18 amp speed controls for the two Himax motors on 5.5:1 gears, spinning 10x8 clockwise and counter-clockwise props. The CG is about 2" in front of the rear prop, and the battery sits in between the two motors to get that CG. It is held in place with velcro, and a velcro strap that goes around the battery and one of the carbon cross braces.

The battery is on the fin that is down in forward flight, so the entire plane is slightly biased to that fin being down. I have the motors and receiver on the opposite side to mostly balance out the battery.

Last week I reduced the diameter of the ducting by a few inches, and moved the entire duct forward a few inches. We found during flip-overs on landing, it would be nice to have the prop completely protected, and moving the duct forward does a good job. The red circle in the second photo is the CG.

Chris
Last edited by chrisgood; Sep 13, 2008 at 01:51 PM.
Oct 26, 2008, 08:23 PM
Registered User
RCvertt's Avatar
That machine is awesome!!!
Do you have any gyros on it to help keep it stable during hover flight?


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Counter rotating props Stef Power Systems 21 Sep 10, 2009 05:08 PM
Counter Rotating Props rc capo Sport Planes 20 Nov 11, 2004 06:36 AM
Counter-rotating prop? f2racer Electric Plane Talk 1 Sep 01, 2002 08:00 AM
Counter rotating props for W. Flyer sky guy Parkflyers 5 Mar 05, 2002 10:26 AM
Counter-rotating rotor mechanism AlGabon Power Systems 4 Oct 30, 2001 11:58 AM