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Old Oct 09, 2012, 01:01 AM
pgts is offline
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Air is huge!
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2PES :-) : one more try for Madstab


Hi,

Here is my own try to have a good movment for madstab, smooth and strong at neutral but wide at extremities... This is my prototype:

2PES - 2 Point Exponential System - for madstab. (2 min 9 sec)


What do you think about that?
I would like to use it on a 1,4Kg glider.
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Old Oct 09, 2012, 01:44 AM
bjaffee is offline
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Brett
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+1 for still using a Futaba Super 7 (my first computer radio).

Old Oct 09, 2012, 02:22 AM
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Biting ankles since '53
Nice bit of thinking there. Can't wait to se the rear linkage.
Old Oct 09, 2012, 11:13 AM
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Wow, that is seriously clever thinking - great work! I just hope you can make it accurately enough to avoid excessive slop. Do you plan to use a a large travel servo to help here? I'm not an expert, but the programmable Hyperions can get up to 175 degrees of movement...
Rotation (degrees): By default most servos, including ATLAS, have 45 degrees rotation per side (90 degrees total). You may program ATLAS for as little as 15 degrees or as much as 70 degrees rotation per side. (30~140 deg total) Note that ATLAS may safely be driven - using Transmitter travel and mixing adjustments - to a max of 175 degrees total rotation.
(From the Hyperion servo programming guide)
Last edited by MattyB; Oct 09, 2012 at 07:32 PM.
Old Oct 09, 2012, 12:09 PM
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rubio
Old Oct 10, 2012, 05:30 AM
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Hi PGTS,

Very clever system, well suited to the bigger VTPR planes.
A few months back I've designed a similar system, with a tow wound around an oval cam.

You'll find that adding another 2PES, rotated 90, to the madstab will give even better expo.

DSCN6138.MOV (0 min 48 sec)


Madcam system (0 min 57 sec)
Old Oct 10, 2012, 09:38 AM
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Hi,

At rear, I have done something more usual. Well, a little bit more usual:









The aim is just to be able to move for +90/-90 and to be strong and precise, but nothing special for exponential movment. Everything comes from system at servo as described on Excel sheet shown on my vid. (here attached).

For the servo, now I only have a S3003. With settings on my oldschool FF7 I have +55/-40. This will allow me to try my system for elevator up, but I will "only" have 45 down...
On Hyperion servo, I don't know if there is a need to have such a system, since they are supposed to be precise and strong. So maybe only with good settings it could be okay on Hyperion? What do you think about that?
Well it is true I would really like to find a cheap servo able to make +55/-55 with my equipments...

Yeah Prop-er I saw your system! This is the kind of system which put me on the track about looking for something... Because I guess yours is to light for 1.4Kg glider, but perfect for ultrabatics!
Old Oct 10, 2012, 10:32 AM
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Quote:
Originally Posted by Prop-er View Post
A few months back I've designed a similar system, with a tow wound around an oval cam.

You'll find that adding another 2PES, rotated 90, to the madstab will give even better expo.

http://www.youtube.com/watch?v=G1X0O...3&feature=plcp

http://www.youtube.com/watch?v=6i70N...2&feature=plcp
Wow, this just gets better - extreme taileron control! Very innovative. Three questions, the first two of which may well be related...
  1. In the first vid the right hand cam represents the servo end and the left hand one the tail end, correct? Or is the left hand one an intermediary between the servo cam and a circular disk at the tailplane root?
  2. Above you say that the second 2PES needs to be rotated 90 degrees relative to the first, but in the second video the tail end cam looks to be the same way round as the servo end - I'm obviously missing something here!
  3. How exactly does the cam connect to the linkage itself - does the tow just wind round it, or is there some kind of "hook and eye" setup?
Thanks!
Last edited by MattyB; Oct 11, 2012 at 06:24 AM.
Old Oct 11, 2012, 02:41 AM
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@Pierre (Best guess!)

That tail end looks great. Nice and solid. Sorry, but I can't help you with your specific radio/servo issue. Maybe it's possible to use a built in offset in your linkage to overcome the asymmetric throws?

@Matty,

1. Correct. In the first video the right hand cam represents the servo end and the left hand one the tail end.
2. You can't actually see the tail cams in the second video. They are very tiny, and buried within the 1/2" wide fuselage. What you can see is the "pick-up" for the removable tail. Pics in the link should clarify this.
3. The tow is connected to the linkage on both tow ends. The tow runs a full rotation around the cam. I put a drop of CA on the tow/cam to prevent slippage.























Vincent
Old Oct 11, 2012, 06:27 AM
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Quote:
Originally Posted by Prop-er View Post
@Matty,

1. Correct. In the first video the right hand cam represents the servo end and the left hand one the tail end.
2. You can't actually see the tail cams in the second video. They are very tiny, and buried within the 1/2" wide fuselage. What you can see is the "pick-up" for the removable tail. Pics in the link should clarify this.
3. The tow is connected to the linkage on both tow ends. The tow runs a full rotation around the cam. I put a drop of CA on the tow/cam to prevent slippage.

Vincent
Thanks Vincent, much appreciated. Great work! I may well scratch up a OD 2-2.5m ultrabatics ship this winter with a madstab; if I do I'll definitely be using a setup like yours!
Old Oct 11, 2012, 07:47 AM
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Originally Posted by 67econoline View Post


rubio
+1

Some really good work being done here!

Chris
Old Oct 11, 2012, 10:57 AM
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I cant wait to see the results...

Rubio


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