Project Rays - Manta - Page 19 - RC Groups
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Dec 21, 2008, 08:22 PM
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Geode's Avatar
Nice job! Keep it coming. Can't wait to see your maiden report.

BTW, what's you AUW?

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Dec 22, 2008, 04:42 AM
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Hi Geode!

Unfortunately it's 350 gramms, the old one was the same. My wing is very heavy (185 gramms)... I think that the ribs are too heavy from the 3mm balsa. 1,5 mm can be a better solution.

In the pod I can save another 10 gramms, becouse the nose cone is my first product and there's a lots of resin in it. The boom is one of the first ones now I can make much more lighter ones.

I've calculate that I know about 35 gramms what I can correct, without the wing.

But I'm working on the composite wing now
Dec 24, 2008, 04:43 AM
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I wish to You Merry Christmas and a Happy New Year with lot of good landings, and nice DLGs!
Dec 24, 2008, 11:57 AM
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Geode's Avatar
Same to you Smash and everyone else.

Merry Christmas,
Dec 25, 2008, 02:39 PM
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I proceeded very good with my next Manta, till today when I realised that I forgot to buy connectors for the wing servos

Now the plane without CF and FG reinforcements, electronics and covering is 185 gr. The final weight will be around 320-350 gr, but I hope the first will be the truth.

The questionable point now is for me the pushrods, it weights 15-20 gr, it is too much, I would like to make a pull-push system like on the bigger aerobatics modells used. Instead of wires I would like to use something lighter material, like fishing line (not the plastic one because stretch).

What is your opinion about that?

Good to see that something from the nothing get ready by me, I haven't feel this for a long time, maybe I haven't built for a long time

Merry Christmas for everyone,
Dec 25, 2008, 03:56 PM
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Hi Vince!

Nice Job!! Love that balsa pod

Maybe You can try a carbon rod wich fits into the bowdens inner case (0,8 mm diameter). At the end of the carbon rod you should join a 0.8 mm steel rod with a ? sintertube ? (zsugorcső ) and a small drop of CA, like I did it on my BUG:

How do you call this plastic tube which sinters by heat?
Dec 26, 2008, 11:20 AM
Where'd The Wise Men Go?!?
AC5FF's Avatar
Smash; Shrink Wrap?

Wincee: Push/Pull system idea: I guess they're semi-common, but I have never seen/tried it until recently. PlasticPaul over in the DragonFly build thread has used this neat and lightweight system for his controls. It is on my DLG and works great. I've been following this thread for a while; but may have missed where this has been commented on in the past...

In essence; it's just a small piece of music wire; bent into a Z except one of the legs is at 90 degrees from the other. This is pushed into the stab and the control surface so that the control surface is held in the full up position. A piece of 8-12lb spiderwire line is tied to the servo/control horn. I think it's quite light in compairison to a push/pull setup
Here is the original elevator setup; you can sort of see the wire and how its installed. This second picture is when I rebuilt my stab. Just above the stab you can see the two "Z" wires that were used (the original and the new one).
Dec 26, 2008, 02:13 PM
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As I understood the carbon rod do the movement all the length of the fuselage. I think it doesn't have enough strength in lateral direction so in this case it have to be fixed to the fuselage, wich provide the same weight which the original construction have (bowden), and it looks worse.


Your solution looks very interesting. I have seen this before on a BUG but instead of the Z wire there was a small rubber which always pull the control surface back.

Why I don't rely on this solution is:

- The servo has to always working because it is always under load. The battery can go dead faster.
- Has the Z wire enough power to hold the control surface when it is under load, I mean could it move the surface to the outmost position under load?
- The servo able to stay back to 0 point?

Of course these my opinion, I'm just skeptic, because I have never tried out, but you are right it is a really light construction for the control surfaces movement.

Dec 26, 2008, 04:20 PM
Where'd The Wise Men Go?!?
AC5FF's Avatar
You have a point on the battery load; I'm really not sure... I know my 300mAh battery will last me at least 2+hrs of flying without any concerns...
Let me see if I understand your second point; will the Zwire move the surface on it's own, without control input? I've never had that happen. I have an Eflite S60 on my elevator; The Zwire will not move the servo at all; even w/power off. I do try to unhook my control line from the elevator when I am storing the plane; just to relieve tention on the Zwire and control surface; but I have never had an issue with the constant pull on the servo.
As for your 3rd point; I have never 'tested' this; but I also don't believe that I have a problem there; My servo appears to be returning to the same zero point. I don't believe that I am continually re-trimming or anything due to a bad zero on the servo.

Hope I answered ya As for using the rubber band; I know Paul tried that recently and went back to the Zwire spring. Not 100% sure why, but.. I seem to remember that the rubber band was giving him problems with movement under load/zeroing... but again, I'm guessing from memory here
Dec 27, 2008, 04:33 AM
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Point 1 and 3 is ok.
Maybe in point 2 I write down my opinion badly

So I get together my english knowledge together and I try to write down what I would .

As I understood point 2:
Basicly the Z wire bend the control surface up, so when you want to move up the control surface the servo hasnt expand any force, just has to let the Z wire to move up the control surface.
When the model is in air and it is flying with "high speed" (example: during launch) and you want to push up the elevator the air expand a pressure on the control surface, the Z wire has to be enough strength to push up the elevator.

So my question was that has the Z wire enough strength to hold the control surface when it is under load and move the control surface to the required position (example the outmost position in upwards)?

I hope now its clear
Dec 27, 2008, 10:47 AM
Where'd The Wise Men Go?!?
AC5FF's Avatar
I see your point now Wyncee.. Reading back to your original question it makes perfect sense.. Maybe I still had too much turkey in my system from Christmas and it was making me a little slow

I would have to answer that question with a resounding "YES!"

Last month I was flying my DragonFly and I didn't notice that the line had come loose from the elevator. Basically it was giving me a near 90degree up elevator when I launched. Needless to say, that launch was NOT pretty! Darn thing almost ripped out of my hand with all the "UP" force. If I had to guess, the air pressure against the control surface DID force the elevator down some, but only because it was at a 90deg bend at the time. If you are wanting to give a little UP elevator during launch, I would say yes; the Zwire would give enough tention to overcome the force of the air across the surface...

Hope that helps
Dec 27, 2008, 01:33 PM
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Geode's Avatar
Did a quick search on RCG for "Pull". There are a few discussions on push-pull / pull-pull / pull-spring. Here is an example,

In my experience, all three do a good job to take DLG launch. The concern on servo loading might not be as much of a problem. Our local DLG guru, once demonstrated the DLG launch with a broken CF push rod (free moving rudder). There is no apparent difference in launch height before and after .... quite a surprise to me

Dec 27, 2008, 03:13 PM
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Thank you for your help,

You prevailed over me.
I'm going to read through the topics and sleep on it wich method do I use and shortly you will see the results.

Dec 27, 2008, 05:05 PM
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"As I understood the carbon rod do the movement all the length of the fuselage. I think it doesn't have enough strength in lateral direction so in this case it have to be fixed to the fuselage, wich provide the same weight which the original construction have (bowden), and it looks worse."

The carbon rod is much more lighter than the steel rod! Once I've measured the difference between the two system, I can't remember exactly and unfortunatley now I haven't got carbon at home, but I think that -10 gramm is guaranteed!


I've got some trouble with my aileron servo so I had to change it that's why the maiden haven't done yet...

Tomorrow I'll get up early in the morning... like the early bird do it

( oh yeah r'n'r )

Do You use any launch/thermik/speed phases?
Last edited by Smash; Dec 27, 2008 at 05:11 PM.
Dec 28, 2008, 03:11 AM
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Geode's Avatar
Yes, these launch/cruise/thermal modes are must have to get the best out of the DLG's. Good luck with your maiden, earlybird :-).

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