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HomeAircraftHelicopterMain Discussion › Has anyone tried coaxial heli CX5 ?
03-21-2015 11:33 PM  3 years agoPost 21
Peter Wales

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Orlando Fl

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Your wish is my command

I took the 1100mm metal blades off this turbine powered version and fitted 875mm blades which caused a bit of vibration, but flew pretty well

https://rc.runryder.com/rrTV-Photo/...ine-Coaxial.wmv

Peter Wales
http://scalehelicopters.org

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03-22-2015 12:14 AM  3 years agoPost 22
ssmith512

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Indianapolis, IN USA

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As soon as there is a KA-50 or KA-52 fuse available to fit these mechanics, I am so getting one of these!!

Too cool.

Steve

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03-22-2015 12:42 AM  3 years agoPost 23
turboomni

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East of the Equator

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Is this machine strictly for scale type flying or can it do a loop or stall turn or inverted flying too? It looks very cool and seems to be very stable.

Setup is everything, All my heli's can fly far better than I can pilot them

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03-22-2015 02:33 AM  3 years agoPost 24
Peter Wales

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Orlando Fl

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KA 52 fuse will be available in a couple of months. The foa is being CNC machined right now. A KA 32 fuse painted may be a little later.

There are problems with negative pitch on these things as the rudder gets reversed but you gyro doesn't know it, so it will spin. Any aerobatics you can do without negative pitch it will do. a Figure 9 loop or a stall turn is certainly in. Rolls at zero pitch, yes. Just dont sk me to demo them, I'm a scale dude

Peter Wales
http://scalehelicopters.org

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03-22-2015 02:42 AM  3 years agoPost 25
turboomni

rrProfessor

East of the Equator

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There are problems with negative pitch on these things as the rudder gets reversed but you gyro doesn't know it, so it will spin.
Wow that is interesting about the gyro inverted. Cool heli for sure.

Setup is everything, All my heli's can fly far better than I can pilot them

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03-22-2015 09:59 AM  3 years agoPost 26
Aaron29

rrProfessor

USA

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It turns by altering the pitch of the top rotor and through a mix, altering the pitch of the bottom rotor in the opposite direction so the overall lift remains the same but the torque exerted by both rotors changes, one up and one down, to remain the same total.
Oh so this is a collective pitch coax? I didn't know such a thing existed, in RC. Yeah so it increases pitch on one set while decreasing the other. So it turns just as the full size coaxes do.

So it's collective. Cool. Can it 3D?

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03-22-2015 12:23 PM  3 years agoPost 27
Peter Wales

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Orlando Fl

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Let me revise my answer concerning negative pitch. You cannot auto it with negative pitch as the yaw control gets reversed. Stay positive or at zero pitch and you will be ok, as long as you can auto without negative pitch that is

As for flying inverted, the answer is, I dont know! It is not set up to fly inverted and I dont fly inverted so I am not going to try it, but I cant think of any reason why it wouldn't fly inverted.

I dont know what would happen to the yaw control when inverted, I would think that as long as it is powered it would be the same as right side up, but thats my guess and it's only a guess.

if I am right, then it should be possible to do 3D with it.

We need a 3D pilot to buy one and run some tests for us

Peter Wales
http://scalehelicopters.org

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03-22-2015 12:48 PM  3 years agoPost 28
ssmith512

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Indianapolis, IN USA

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KA 52 fuse will be available in a couple of months.
COOL!!!!! I know what my winter build is going to be!!!

Steve

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03-22-2015 02:41 PM  3 years agoPost 29
Phoenix NOTAR

rrApprentice

Tallahassee, Florida USA

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As a long time citizen of the Scale Community, I have learned that it is typically unwise to disagree with Peter Wales in a forum. So, that being said, maybe my CTX-5FBL is different than his

On my CTX-5FBL, the yaw control system (mixer yoke) attaches ONLY to the clockwise rotating upper rotor head, and so it affects the pitch only on this upper head. To yaw right, the yaw control system “lowers” and reduces the collective pitch of the upper head (only). Now the drag / torque / pitch on the lower counterclockwise rotating head is greater, and the helicopter yaws right (clockwise). As noted in my post above, the helicopter will lose some altitude when this occurs since the total collective pitch of both rotors is now less. This is barely noticeable though (at least to me).

Since right yaw is accomplished by reducing the collective pitch on the upper rotor system, everything works great until you start flying at or near zero degrees of collective pitch on this rotor system. If you are near zero degrees of collective pitch, and try to yaw right, the yaw mixer will reduce the collective pitch on the upper rotor system which will actually ADD negative pitch to this rotor head, which will have the effect of making the helicopter yaw LEFT. Now a skilled pilot may be able to correct for this, but the current gyro systems being used will sense this yaw to the left and try to correct it by lowering the yaw mixer system (typically a right yaw command) which will add more negative pitch to the upper rotor head causing the helicopter to yaw more left, and well, you can guess were this scenario ends up….. Unless you increase the collective pitch into positive pitch again.

So, flying without a tail gyro, or with a tail gyro that will reverse sensing direction when the upper head collective pitch crosses into negative pitch may work just fine .

For aggressive or 3D type flying with this model, keep in mind that the supplied blades are quite flexible. The manual states; “The NYGF (plastic) blades suit gentle flight. If you would like to do an aggressive & violent flight, we suggest you to use carbon blades.”

I agree that a 3D pilot should buy one and try it out inverted and report back to us.

Sandy

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03-22-2015 03:11 PM  3 years agoPost 30
don s

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Chesapeake, VA

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Is the "rudder" control also in rate mode?

E820, Raptor G4N, X50F/E, E620, Forza 450, and some planks.

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03-22-2015 03:21 PM  3 years agoPost 31
Phoenix NOTAR

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Tallahassee, Florida USA

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I have both "rate" and "heading hold" mode set up in my FBL system for yaw (rudder). I typically spool-up in rate mode, and fly in heading hold mode. Both would work as I described in my post above.

Sandy

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03-22-2015 04:08 PM  3 years agoPost 32
Peter Wales

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Orlando Fl

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I'm not quite sure what you are disagreeing with me about Sandy, kindly explain further

Peter Wales
http://scalehelicopters.org

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03-22-2015 04:12 PM  3 years agoPost 33
don s

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Chesapeake, VA

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Anybody run it gyro-less?

E820, Raptor G4N, X50F/E, E620, Forza 450, and some planks.

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03-22-2015 04:31 PM  3 years agoPost 34
Phoenix NOTAR

rrApprentice

Tallahassee, Florida USA

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Hi Peter,

Thanks for asking.

In an earlier posted you stated;
It turns by altering the pitch of the top rotor and through a mix, altering the pitch of the bottom rotor in the opposite direction so the overall lift remains the same
On mine, yaw does not alter anything on the bottom rotor system. The total collective pitch of the heli (lift) does change a bit with a yaw input.

Sandy

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03-22-2015 04:34 PM  3 years agoPost 35
Peter Wales

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Orlando Fl

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And thats why you program a mix into your transmitter to keep it level in the turns

Peter Wales
http://scalehelicopters.org

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03-22-2015 04:42 PM  3 years agoPost 36
Phoenix NOTAR

rrApprentice

Tallahassee, Florida USA

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Got it, Thanks. We are 100% in agreement then.

I was only referring to what mechanically happens on the rotor system on this helicopter.

Sandy

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05-09-2015 06:43 PM  3 years agoPost 37
Ronita

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UK

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Anyone have more info on the CTX5-FBL? Have posted on other forums but all is quite. Surely someone must have taken the plunge by now?
Desperate for operational reviews!

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05-09-2015 10:03 PM  3 years agoPost 38
Phoenix NOTAR

rrApprentice

Tallahassee, Florida USA

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Ronita,

What is it that you want to know about the operation of this heli?

Peter and I have been flying them around. I was just at a Fun fly in Fredericksburg, Virginia (USA), and flew it 5 times at that event.

Model helicopter World magazine (U.K.) did a full article on it in their March 2015 issue.

Ask a specific question about it here on the forum if there is something you would like to know about it, or PM me if you prefer.

Sandy

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05-10-2015 11:39 AM  3 years agoPost 39
Ronita

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UK

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Phoenix NOTAR
Thanks for the reply. I'm interested in any general news or experiences of this new fascinating product. I plan to buy a kit quite soon from East Coast in the USA which will be hand carried to me here in the UK by my son. No UK dealer exists as far as I know.

Of particular interest are the various options regarding FBL controller, servo options, Rx and/or sats used, battery requirements, etc. Experiments with larger rotor blades, say 450mm or more. Tuning or setup problems.

Perhaps the stock setup requires no fiddling and flies just great as is. Videos seem to show some height loss on turns or bobbing up and down in forward flight. But this could be my imaginations! Flights appear to be relaxed and enjoyable!

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05-10-2015 01:14 PM  3 years agoPost 40
Phoenix NOTAR

rrApprentice

Tallahassee, Florida USA

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As noted in the beginning of this thread, there is a nice build thread here:

https://rc.runryder.com/t782696p1/

Peter also notes using both high end FBL systems, as well as a "budget" unit. I am using a older Helicommand (now Bavarian Demon) HC3 Xtreme, and it is working well for me.

I am using the same servos as Peter, 4 x Savox SV1250MG. They are working well, but I did need to notch a bit of the frames away in two corners to get them in the proper position. I use a Jeti radio system, but I believe any radio / receiver will work fine. I am using a Zippy 5S 4400 mAh battery and I get 8+ minutes of flight time. The battery box can fit a bigger battery, but this one fits in snug in one direction, and these are the packs I used in the older "heli Baby" coax I have.

The included plastic 390mm long, very flexible, blade work for me as long as the there is no wind to a light breeze. If there are strong gust of wind they go out of track and set a vibration in the heli. I am trying to get two matched pairs of 3 blades sets of symmetrical 423mm / 425mm carbon blades to use instead. I have not found a set yet. I think this will solve this issue of the flying in windy conditions for me.

Mine does not "bob" in forward flight, and Peter has posted a video above that his does not either. Any heli will not fly perfectly if the FBL system has not been optimized.

I can notice a slight hight rise or fall if I am doing stationary pirouettes, but so what, just add or reduce the collective. If you cannot do that then you should not be flying a model heli.

You can probably use any length blades you want since they are not going to hit the "tail rotor". Bigger heavier blades I assume will use more power, but I do not know what effect good or bad it may have on flight. Hopefully I will know about 425mm blades soon.

I found a few small things I revised as I built the kit, but it is not worth noted in this post, as it would not make any sense unless you had the kit in front of you. If you get one, post or PM me and I will explain the few things I did.

Sandy

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