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Old Oct 28, 2012, 10:13 AM
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Missouri
Joined May 2010
81 Posts
Quote:
Originally Posted by mazjag View Post
Thx Gadget, for the trim list...My problem is the guy looking at the plane to trim it, is me.. I`m not sure what I`m seeing all the time is correct..It has gotten windy in Atlanta and thats not helping. Anybody here? These things don`t need the CG set like a 3D plane correct? I keep trying to roll upside down and keep moving the battery back...I`m not so sure it flys better...How much down should it be inverted? a touch? I know enough too know I need help with that first...thx..J
Mazjag,
I am with you. I have only been flying for 3 years so trimming a plane is a skill I need to develop. Goldsmith's article and trim chart helped me immeasurably. Now I know how a good pattern plane is suppose to fly.

I am going to try Jim Lee's suggestion of using less expo with down elevator than up elevator. Previously, I set the CG according to 3DHS suggestions but it didn't feel right to me. I like a touch of down elevator when I'm flying inverted but probably had to use more than a touch because of the amount of expo I had programmed in to the radio. I think Jim's suggestion will make the correct CG feel correct to my personal preferences.

Best of luck
Gadget
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Old Oct 28, 2012, 10:59 AM
"...certainty is absurd."
kcaldwel's Avatar
Joined Jan 2007
3,601 Posts
Gurney flap and T-Flap papers:

http://www.dept.aoe.vt.edu/~mason/Ma...A2007-4175.pdf

http://www.cirodesignracing.com/Ciro...20research.pdf

The CG on the Osiris has me confused lately too. I flew it for a long time just aft of the recommended, at 127mm. It still felt a bit nose heavy to me there - the nose drops after rolling to inverted on a 45 degree up-line, and it takes a bit more down elevator inverted than I would like.

I calculated the aircraft neutral point at 172mm, which seemed impossibly far back given the recommended CG and how it behaved. I couldn't understand the discrepancy, because I've never been anywhere near that far off on any other airplane.

I have lately started moving the CG back, and strangely the aircraft behaviour doesn't really change much over quite a large range. Last time out, I had the CG at 165mm back! The airplane is starting to get neutral, so my calculated neutral point looks like it might be close.

I've never had an airplane that behaved essentially the same, to my limited skills, over such a wide CG range. I had a much better pattern pilot than me fly it at 127mm, and he thought it was almost neutral there. I'll have to get him to try it again, and see if I've messed it up entirely.

It is easy enough to fly with the CG back that far, and it doesn't feel tail heavy to me yet. I have pretty small elevator throws, but I haven't changed that since I had it at 127mm.

Kevin
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Old Oct 28, 2012, 11:36 AM
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Marietta GA.
Joined Jan 2011
332 Posts
I agree...I seem to be having to move the battery far pack from the bench CG 110-125mm back to get it to the fly inverted without a good bit down elevator..I fly with 3000ma packs and have moved the pack all the way back to the center of the H where it says 3d hobby shop on the battery tray..My bench CG is about 1" farther foward..
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Last edited by mazjag; Oct 28, 2012 at 09:24 PM.
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Old Oct 28, 2012, 08:44 PM
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Missouri
Joined May 2010
81 Posts
kcaldwel,

Wow, those are some heavy papers. What is the size of the t channel you have been using on your Osiris rudder? I would like to try one on my plane.

Gadget
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Old Oct 28, 2012, 09:26 PM
"...certainty is absurd."
kcaldwel's Avatar
Joined Jan 2007
3,601 Posts
That's my light reading!

My T-flap sticks out about 6mm each side of the rudder near the bottom, and about 4mm near the top each side.

Just got myself a 62" Osiris all outfitted with great equipment today!

Kevin
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Old Oct 29, 2012, 11:08 AM
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United States, IL, Chicago
Joined Nov 2007
128 Posts
As I understand it, the tailwheel wire should go through the hole at the narrow end of this bracket, and you put a wood screw in the hole at the fat end.

The wire doesn't fit into the hole, though. Should I just drill the hole out a bit?
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Old Oct 29, 2012, 11:30 AM
inverted-i-fly
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United States, CA, Petaluma
Joined Mar 2011
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my tail wheel broke on the 6th flight, I'm now using this one,
http://www.extremeflightrc.com/store...roducts_id=111
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Old Oct 29, 2012, 05:07 PM
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United States, AZ, Quartzsite
Joined Mar 2002
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Quote:
Originally Posted by Neko View Post
As I understand it, the tailwheel wire should go through the hole at the narrow end of this bracket, and you put a wood screw in the hole at the fat end.

The wire doesn't fit into the hole, though. Should I just drill the hole out a bit?
Yes to answer your question.

My tail wheel wire broke on my first Osiris at the 90 deg wire bend. It's a minor design error because, depending on how the bottom of the rudder and the fuse line up, the wire bend could take all the stress. On my second plane I offset the mount with a piece of light ply so the mount takes the stress not the wire. Has work well in Osiris #2 and now in #3 with no failures .
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Old Oct 29, 2012, 09:10 PM
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Missouri
Joined May 2010
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Quote:
Originally Posted by kcaldwel View Post
That's my light reading!

My T-flap sticks out about 6mm each side of the rudder near the bottom, and about 4mm near the top each side.

Just got myself a 62" Osiris all outfitted with great equipment today!

Kevin
LOL I'm a biologist not an engineer. I sure appreciate your expertise.

What did you use for your right angle stock?
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Last edited by Gadget99; Oct 29, 2012 at 09:11 PM. Reason: misspelling
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Old Oct 29, 2012, 09:40 PM
"...certainty is absurd."
kcaldwel's Avatar
Joined Jan 2007
3,601 Posts
As I mentioned above somewhere, I just used a strip of red polyethylene from a snow slider magic carpet thing. I always buy a bunch of those in the spring when they go on sale for a buck or two. They are nice PE that I use for all sorts of things like cheap "mylars" for bagging, or tough T-flaps for a rudder.

I just sanded the mat side and the TE of the rudder a bit, and glued it on with flexible CA and a bit of baking powder to kick it and make a fillet.

Kevin
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Old Nov 02, 2012, 03:53 PM
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United States, CA, Long Beach
Joined Sep 2011
827 Posts
So about done with mine just need to get the rates setup. Hooked up a watt meter and get the following:

41a
571 watts

2650mah 4s battery 30c
Omega 130g engine
11 x 7 prop

Sound about right? Just from it pulling I'm pretty sure it will be enough to fly

Might try the 12 x 6 for comparison.

Robert
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Old Nov 02, 2012, 04:19 PM
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United States, CA, Long Beach
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so 12 x 6 prop is 581 watts at 42A.

Seems like it pulled a lot more but may have just been me.

Robert
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Old Nov 02, 2012, 07:46 PM
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Marietta GA.
Joined Jan 2011
332 Posts
That`s the set-up I`m using with the 11x7...I did have a problem when I tried to use some of my older 2650ma 30c packs that the speed control would cut out at a full throttle punch...I just fly it on 3000`s now..My `51 slick flies on those same 2650 packs no problem which I found odd...about the same amount of watts, but different ESC. I would shoot low on the rates and put in some expo...It doesn`t need much throw to get pretty twitchy..
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Old Nov 03, 2012, 02:15 PM
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United States, IL, Chicago
Joined Nov 2007
128 Posts
6 flights on mine now. Hacker A30-14L, 11x7 and 4S 3300. Canopy flew off today and the supporting wood parts broke in several places. That was exciting. Otherwise, I am enjoying the feeling of my first plane with no dihedral.
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Old Nov 03, 2012, 02:51 PM
"...certainty is absurd."
kcaldwel's Avatar
Joined Jan 2007
3,601 Posts
The trick with the canopy latch is to take a small round file and make the bottom of the slot for the latch pin go straight in. As it is, the bottom of the slot goes up, perpendicular to the angled back of the canopy. That makes it so the latch pin doesn't go through the plywood plate, and the canopy can fall off.

Easy two minute fix to make the latch pin go all the way in.

Kevin
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