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Old May 24, 2009, 05:43 PM
LSF - IV
Hostage-46's Avatar
United States, TX, Highland Village
Joined Jan 2003
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converting a power Zagi to slope

Any secrets here guys? One of my buddy tells me to leave the motor in it, but that seems ... well nuts...

I plan in cobbling this thing together with parts lying around. So I'll end up with a decent sized lipo battery, servos will be fine. I'll take off the motor hump and maybe make a little box to keep all that stuff below the top of the wing. Anything else?

How about mods? Anyone fiddle with the fins on the ends? Move
'em to the center, maybe add a rudder? Ok... I'm reaching here...

Dan in Dallas ... flat lander with a slope in just a few more days...
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Old May 24, 2009, 06:06 PM
Pompano Hill Flyers
Miami Mike's Avatar
Miami Lakes, Florida, USA
Joined Mar 2003
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Just strip off all the gear you don't need to lighten it as much as possible, install four AA cells near the nose to keep the CG where it was before, clean up the top to minimize drag, and fly it.

A rudder won't be of any use, but one of our club members substituted a center fin for the winglets on his Zagi sloper and made it look sort of like a Halfpipe. He was happy with the results.
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Old May 24, 2009, 06:16 PM
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United States, CA, North Highlands
Joined Aug 2004
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Hey Dan,
Have you been peeking at my secret Zagi mods?
I got rid of all the plastic and the winglets and added one central fin with just a tad more area than the winglets combined. My son flys the snot out of it and it just keeps going saggy wings and all
CG is in the original location, if you have good lift a little extra weight won't hurt
I run a spektrum flight pack battery that came out of a standard size flight pack.

Dave
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Old May 24, 2009, 08:20 PM
LSF - IV
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United States, TX, Highland Village
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That's exactly what I was thinking, I figured it might roll better with less mass at the tips.... so what would happen if I added a rudder to that fin?
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Old May 24, 2009, 09:26 PM
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Chino Hills, CA
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Quote:
Originally Posted by Hostage-46
That's exactly what I was thinking, I figured it might roll better with less mass at the tips.... so what would happen if I added a rudder to that fin?
Rudder won't be effective because the fin is very close to the cg, having less leverage compared to the full fused planes.

If you want, you should be able to just slope your wing as it is. It's not going to be as efficient as taking the motor off , but you will have nice option of powering out when the lift dies which could be helpful if you've never sloped before. Of course the extra weight will require more lift.

Center fin mod will make your wing faster because of less drag than two wingtip fins, but it will take more time to recover from hits if you decide to use your wing for combats.

Adrian
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Old May 24, 2009, 09:31 PM
Pompano Hill Flyers
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Miami Lakes, Florida, USA
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Quote:
Originally Posted by codezilla
Rudder won't be effective because the fin is very close to the cg, having less leverage compared to the full fused planes.
And beside that, what would you use it for?
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Old May 24, 2009, 11:45 PM
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Quote:
Originally Posted by codezilla
Rudder won't be effective because the fin is very close to the cg, having less leverage compared to the full fused planes.

Indeed that makes sense.... dug out the old bird, simple enough to have her ready to go in a one evening of shop work ... this ought to be a gass.....That motor and Nicad battery we're like a freaking anchor... should be nice and nimble.
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Old May 24, 2009, 11:58 PM
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Quote:
Originally Posted by Hostage-46
Indeed that makes sense.... dug out the old bird, simple enough to have her ready to go in a one evening of shop work ... this ought to be a gass.....That motor and Nicad battery we're like a freaking anchor... should be nice and nimble.
Your CG may need to be readjusted also. A lot of powered wings are nose heavy because they can get away with it with power. If it flies like a dog on the slope, that's probably the most likely cause. Slowly move the CG back, and also slowly DECREASE the elevator throw. When the CG is spot on, you'll be barely moving the elevons for elevator control.

Adrian
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Old May 25, 2009, 03:13 AM
Biting ankles since '53
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I have a wildWing for the slope and the first thing I did was fit a centre fin and move the CG back. Flies great.





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Old May 25, 2009, 04:03 AM
Tearing the Skies a new one...
Sensiblenick's Avatar
Sweden: Ystad
Joined Oct 2004
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Quote:
Originally Posted by Hostage-46
So I'll end up with a decent sized lipo battery
Hey you in the warm hot, arid bush-fire-tastic America type thing.... Definitely a BIG no on the LiPo in a sloper.

There are many reasons why... This simple google search should show a few.

Go for a really simple 4 or 5-cell AA NiMh pack, and that'll give you a day's flying
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Old May 26, 2009, 12:02 PM
LSF - IV
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United States, TX, Highland Village
Joined Jan 2003
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Quote:
Originally Posted by codezilla
Your CG may need to be readjusted also. A lot of powered wings are nose heavy because they can get away with it with power. If it flies like a dog on the slope, that's probably the most likely cause. Slowly move the CG back, and also slowly DECREASE the elevator throw. When the CG is spot on, you'll be barely moving the elevons for elevator control.

Adrian
Adrian,

I tend to fly an aft CG, can you give a point of reference where to start? How about the elevator throws, how do you define "barely" moving...

Appreciate the pointers, hope to be out this weekend, now that we have a slope, I'll bet the winds go down!

Dan in Dallas..
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Old May 26, 2009, 04:18 PM
Its not IF... Its WHEN.
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West Yorks
Joined Feb 2007
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Quote:
Originally Posted by Sensiblenick
Hey you in the warm hot, arid bush-fire-tastic America type thing.... Definitely a BIG no on the LiPo in a sloper.

There are many reasons why... This simple google search should show a few.

Go for a really simple 4 or 5-cell AA NiMh pack, and that'll give you a day's flying
Hi Nick

Sensible advice as always...

Did I hear it right that some grass snakes ate the Retox moulds??

Good to hear you're still about buddy - hope the move went well

Tim
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Old Jun 10, 2009, 09:25 PM
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United States, TX, Highland Village
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Behold, my flat lander trashslope ship

This Zagi was a typical power zagi. I converted it to a tapeless setup, adding in some carbon spars and covering with monokote..that saved weight and made the wing nice and stiff lost a few oz.

This time around I collected some loose ends around the shop..

Removed half the weight, she now comes in at 12 oz.
2.4 Spektrum receiver. 1280 nimh pack and a switch jack charger.
Fresh ultracote and a center fin... looks about right.

Gave her a few tosses in the yard, CG was too far aft, control throws too big. Swapped the location of the battery and receiver, tuned the throws down a bit and viola... we're in business.

Tomorrow... to the dump!
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Old Jun 11, 2009, 09:16 AM
Tearing the Skies a new one...
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Sweden: Ystad
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Quote:
Originally Posted by Hostage-46
Tomorrow... to the dump!
I know it's a Zagi, but at least try to fly it first....
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Old Jun 11, 2009, 10:02 AM
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Chino Hills, CA
Joined Feb 2003
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Quote:
Originally Posted by Hostage-46
Adrian,

I tend to fly an aft CG, can you give a point of reference where to start? How about the elevator throws, how do you define "barely" moving...

Appreciate the pointers, hope to be out this weekend, now that we have a slope, I'll bet the winds go down!

Dan in Dallas..
Hey Dan, didn't see this post until today.

I don't have a zagi, so I can't tell you where the CG should be. The way I do it is to start slightly nose heavy to "safely" dial in the throws, then move the CG slowly to the back while decreasing elevator throws, then when it's almost impossible to fly, I move the CG just a bit forward maybe about 1/8" to 1/4" and be done with it.

As for the barely moving, on my Windrider Bee, it used to be approximately 1/16" up/down (for elevator, for ailerons max throw) maybe less.

Adrian
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