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Mar 12, 2018, 09:35 AM
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Extreme Sports's Avatar
You can move the battery back ONLY IF the CG is still ahead of the 30% point. If, at that CG location, you still need full up elevator, regardless of throttle, then negative decalage is most likely the cause. Moving the CG further back just makes the plane less stable and therefore very sensitive to elevator input. Go back more than ~33% and the plane will be very difficult if not impossible to control. Rather re-attach the horizontal stabiliser at the right angle and your plane should fly with neutral elevator.
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Mar 12, 2018, 08:24 PM
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Sushmit's Avatar
Quote:
Originally Posted by Extreme Sports
You can move the battery back ONLY IF the CG is still ahead of the 30% point. If, at that CG location, you still need full up elevator, regardless of throttle, then negative decalage is most likely the cause. Moving the CG further back just makes the plane less stable and therefore very sensitive to elevator input. Go back more than ~33% and the plane will be very difficult if not impossible to control. Rather re-attach the horizontal stabiliser at the right angle and your plane should fly with neutral elevator.
OK I see will check the Hs.
Mar 13, 2018, 09:35 PM
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Sushmit's Avatar
Adjusted Cg at 40% and we for flight increased motor angle by 2 and fly like anything.

Can do Flips and rolls. Soon going to add fpv
Mar 15, 2018, 12:21 AM
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Sushmit's Avatar
Here is the flight video of the plane.


Now only problem left is unresponsiveness at low speed


Flying homemade Pusher Rc Plane - Thermacol (3 min 45 sec)
Mar 15, 2018, 09:21 AM
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rajazo's Avatar
Check the stiffness of the tail boom. Flection at higher speed could produce unwanted pitch... in this configuration a dive for sure
Mar 15, 2018, 10:53 AM
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Sushmit's Avatar
Made fuselage v3 with 3 carbon fibre rods 500mm 3mm diameter.
More angle is provided as Cg is shifted to 1/3 of chord instead of 1/2.
Mar 15, 2018, 08:34 PM
I Look, Listen, and Learn
Timbo383's Avatar
Quote:
Originally Posted by Sushmit
Made fuselage v3 with 3 carbon fibre rods 500mm 3mm diameter.
More angle is provided as Cg is shifted to 1/3 of chord instead of 1/2.
You are going in the correct direction on this 3rd fuselage, This new one should give you a really good plane to fly.
Mar 15, 2018, 10:58 PM
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Sushmit's Avatar
Got some old wings to compare the size of the jew wing. Earlier I used simple camber airfoil this time I used deep camber airfoil which increases the lift.
Mar 16, 2018, 03:32 AM
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Sushmit's Avatar
V3 ready for flight
Mar 17, 2018, 09:55 AM
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Sushmit's Avatar
Added the hd camera on the wing using some Foam on counter side to balance the weight of esc at left.
Mar 18, 2018, 08:11 PM
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Sushmit's Avatar
Enough of foam now I have shifted to corro 2mm planes.
Mar 19, 2018, 05:53 AM
I Look, Listen, and Learn
Timbo383's Avatar
Scroll down in the forums column to the SPAD thread, you can learn many ways to make planes with coro.
Mar 26, 2018, 12:21 PM
Scratch building addict
rotagen's Avatar
One big note about Coroplast... It is SUPER heavy stuff and you will no doubt need powerful heavy equipment to fly your plane and you must keep the speed up.... Even 2mm - if you make a double layer wing will be pretty heavy.

I forgot in my previous post to mention that your motor was above your wing and behind the CG so you needed to point it down to keep it from pushing the nose downward from the thrust... but you figured that out, awesome... and you can play with the angle.

Watched the vid. I don't think tail boom stiffness was a problem especially since you have a CF rod in there.

I like your simple design.

The vid looked to me like it was tail-heavy but luckily it was still flyable.

Use an online calc, I like this one because it considers the horizontal stab, and I have used it to good effect.

Here's what I do for a very stable nice flying plane: Set Static Margin to 12%... this has worked perfect on at least 6 models.

http://rcacf.com/HelpfulHints_files/CG_Calculator.htm

I Balance it on a homemade thing, simple section of 2x6 board with holes drilled and two 1/8 inch dowels of exact same height glued into the drill holes about 14 cm apart.

Mark your cg with a permanent pen on the wing and balance your plane... then don't mess with it keep it there.

Simple test you probably already know, if it has an up or down pitch problem that is worse under more speed... you have a motor thrust angle or wing/tail incidence problem (also check the obvious make sure elevator is properly trimmed).

If the pitch problem is almost immediately apparent under slow takeoff and also when throttling down.. then I would worry about CG.

Just a few tips from an old fart like me.
Mar 26, 2018, 02:11 PM
Registered User
Extreme Sports's Avatar
Quote:
Originally Posted by rotagen
One big note about Coroplast... It is SUPER heavy stuff and you will no doubt need powerful heavy equipment to fly your plane and you must keep the speed up.... Even 2mm - if you make a double layer wing will be pretty heavy.
Not quite true. Corro has developed a bad reputation for many reasons, not least among them that some folks seem to take pride in making their corro planes both ugly and heavy...and using glow power. With a bit of care and effort, 2mm corro planes can be made to fly very well on the power set up that Sushmit uses. I've got a few running on ~60W blue wonder setups. Of course it's never going to be as light as depron, but it is many times tougher. But most of my corro planes end up at an AUW are comparable or lighter than equivalent sized RFT foamies.

Take a look at the last 10 or so pages of this thread to see the variety of builds possible with correx: https://www.rcgroups.com/forums/show...-P-A-Ds/page54

And if you have time to spare, lots of ideas on techniques to build with correx here: https://www.rcgroups.com/forums/show...and-techniques
Mar 27, 2018, 12:39 PM
Scratch building addict
rotagen's Avatar
That's good to hear because I actually have a box of some 2mm coro somewhere. I even tooled with the idea of making a "beer box" plane from that coated cardboard they use for beer cases at costco.....just for kicks and fun.

I wonder which would be heavier per area, 2mm coro or that cardboard? Coro is definitely tougher, but those heineken boxes are pretty tough and water repellent.


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