RG 65 Mass Build? - Page 2 - RC Groups
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Nov 11, 2014, 11:39 AM
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FWAL's Avatar

Rebel


I've started drawing the Rebel's hull plan and section. Not too much detail to begin with as I don't want to overcomplicate the drawing with lots of lines prior to transposing the LWL, beam, rocker and shearline dimensions into shadow section drawings.
The beam is 9cm, transom 5.5cm and rocker 3.7cm
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Nov 11, 2014, 12:05 PM
Registered User
Hi FWAL
nice to see i'me not the only seat of my pants pencil and paper guy out there.
Nov 11, 2014, 02:14 PM
Registered User
Looking good FWAL, I see you come up with a good name too

I'm still tweaking stuff, like you not sure about displacement, rocker is about 3.43cm, transom 4.4 and beam about 8.8 cm so we seem be in the same ballpark at least. I'm not happy with the underwater shape of my effort but this software is a bit of a steep learning curve ( move one yellow line, oh that bit has gone wonky, move another yellow line and it's all gone to @%#$! Give up for the night, rinse and repeat)

Thanks for posting your drawing, least your doing it proper
Nov 11, 2014, 03:10 PM
FROM THE MIND OF A MADMAN
gpzy's Avatar
A great site on building RG65s. Lots of pics and build logs. Google RG Andy and run it through a translates if you don't speak German.
Nov 11, 2014, 03:11 PM
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FWAL's Avatar
Hi Tim
Even though our designs have similar primary measurements in cross section they will be poles apart. In the midships the ellipse will on a horizontal plane providing a flatter more buoyant shape which will blend to a slightly more semicircular transom. The idea is to dampen the occasional nodding dog whilst providing an easy water exit off the hull.
We'll see
Nov 13, 2014, 03:09 PM
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Today I drew out the 14 shadow station templates. I used the primary dimensions from the hull cross section and plan. I've tried to explain how easy this process is on my RC Blog
https://www.rcgroups.com/forums/member.php?u=340972
Nov 18, 2014, 02:28 AM
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Rebel


14 shadow templates cut out and glued onto 5mm thick foam board. I use yellow paper to draw the sections onto as it stands out from the foam board to allow for easier cutting.
Dec 02, 2014, 02:51 PM
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Cantilever sail arm


When my head hit the pillow last night and my imagination kicked into the usual modelling hyper drive a cantilevered sail control arm flashed into my minds eye. All of a sudden I could see how a normal length servo arm might provide enough sheet travel for my latest Rebel RG65 project.
This evening I set about knocking up a crude experiment just to see if my idea had any legs and I was quite impressed. A normal servo arm radius of 25mm provided 100mm of sheet travel. Another advantage is the torque isn't jeopardised and it's also relatively light. All together a win, win idea perhaps.
The first photo shows a standard futaba 3001 servo in the sheeted in position and in the second photo the servo is in the sheeted out position. The geometry can be improved slightly to further reduce the holding torque required whilst in the sheeted in position.
Dec 02, 2014, 04:28 PM
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Dick L.'s Avatar
not exactly sure what I see/am looking at. Maybe a bit more info on what the parts represent .... like the screw at bottom right corner?
Dec 02, 2014, 05:18 PM
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Quote:
Originally Posted by Dick L.
not exactly sure what I see/am looking at. Maybe a bit more info on what the parts represent .... like the screw at bottom right corner?
Hi Dick
Firstly ignore the marker pen "in-out" writing, that was there just to measure the overall travel distance. The two small screws in the standard servo arm and the screw in the fixed position in the bottom right are acting as pulley turning blocks.
The sail control sheet is tied off through the top penultimate preformed hole in the servo arm. From there it runs to the fixed position screw (bottom right) and back up to the servo arm (1:2) then across the servo arm 50mm diameter around the other small screw (pulley) to a through deck fitting where it will attach to the sail sheets and bungee take up.
When the servo arm is set in the 'in' position the top screw is furthest from the fixed position screw and the bottom screw is furthest from the through deck fitting and the opposite occurs when the servo is set to the 'out' position.
A better mind than mine would have to work out if the 25mm distance from the fulcrum and leverage forces acting on both sides of the servo arm would be less than a more normal extended servo arm but you certainly don't require as much room.
I hope this helps
Mk
Dec 02, 2014, 05:36 PM
Lucas
Nice description FWAL. Seems like a clever way to trade compactness for a little friction.
Dec 03, 2014, 05:59 AM
Registered User
Hi FWAL

Glad your making progress, i'm still gathering stuff for my build. I have carbon fin, rudder and fin box from Dave creed sat on my bench so I have to build something now!
Dec 03, 2014, 10:17 AM
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Dick L.'s Avatar
FWAL
is it true the distance of the fixed screw from the arm determines the amount of sheet movement?

This would allow a lot of movement if stretched inside a thin cat hull if I understand correctly.

Dick
Dec 03, 2014, 11:11 AM
Useful Idiot
Quote:
Originally Posted by FWAL
When my head hit the pillow last night and my imagination kicked into the usual modelling hyper drive a cantilevered sail control arm flashed into my minds eye. All of a sudden I could see how a normal length servo arm might provide enough sheet travel for my latest Rebel RG65 project.
This evening I set about knocking up a crude experiment just to see if my idea had any legs and I was quite impressed. A normal servo arm radius of 25mm provided 100mm of sheet travel. Another advantage is the torque isn't jeopardised and it's also relatively light. All together a win, win idea perhaps.
The first photo shows a standard futaba 3001 servo in the sheeted in position and in the second photo the servo is in the sheeted out position. The geometry can be improved slightly to further reduce the holding torque required whilst in the sheeted in position.
Unless you've worked a miracle, there's no way you cannot affect the torque rating and increase sheet travel simultaneously mechanically. The power of a servo is torque x speed and is constant. Therefore if you increase sheet travel, you must decrease torque by the same proportion, as in double hauling.
Dec 03, 2014, 11:39 AM
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Quote:
Originally Posted by martin richards
Unless you've worked a miracle, there's no way you cannot affect the torque rating and increase sheet travel simultaneously mechanically. The power of a servo is torque x speed and is constant. Therefore if you increase sheet travel, you must decrease torque by the same proportion, as in double hauling.
I know I'm affecting the torque but would my method require less torque than the more normal extended arm? Also, I'm a bit dumb so can you please explain how increasing the sheet travel decreases torque? Surely you mean increasing the length of the servo arm decreases torque

Hi again Dick
I'm afraid the distance from the servo to the fixed screw wouldn't have any bearing on the amount of sheet travel. It's only purpose is to provide a static point for a pulley which provides a 1:2 purchase with the pulley fixed on the top of the servo arm. The amount of sheet movement is governed by the servo end points and the length of the servo arm.
I was trying to devise a sheeting system which only required the parts supplied with a standard servo. Hence the 25mm radius of a futaba control arm.


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