Forward Swept Wings (FSW) and wingtip motors? - RC Groups
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Jul 15, 2002, 07:24 AM
Peter K's Avatar

Forward Swept Wings (FSW) and wingtip motors?


I build a flying wing, fsw with 2 speed300 at the wingtips.
Which aerodyn. problems may have this configuraton? How to solve?

THX for your help
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Jul 15, 2002, 11:54 AM
Ascended Master
Sparky Paul's Avatar
Excessive rotations in roll due to the spacing of the motors.. Heavy ojects, far from the center of the plane.
The wing will weigh more due to the structure to mount the motors.
Should fly OK.
EPP and foam and electrics are good for this kind of wild-blue testing.
Jul 15, 2002, 03:00 PM
Peter K's Avatar
Yes, the rotation of this mass in the wingtips may be a problem. Perhaps i can move the motors inwards (about 20 cm), if I use lighter cells ... 500AR instead of 1850 Twicells.

I also expect structural problems in the center of the wing, because I have to build light in this area behind CG (I use EPP).
Jul 25, 2002, 04:15 PM
Peter K's Avatar

igaZ is ready ...

It works!

WS 109cm, 730g, 2 x Speed 300, 7 x 1850 NiMh

Launching is a little bit tricky, but performance is better than expected, including rolls, loops, flying on back ...

Looks quite strange ....

Last edited by Peter K; Jul 26, 2002 at 02:17 AM.
Jul 25, 2002, 05:37 PM
Ascended Master
Sparky Paul's Avatar
Looks OK to me....
Would putting a smallish "fuselage" at the center help give a better launch situation? Something that would let you grab it ahead of the c.g.?
Just a profile grip/shape.
Sparky Paul
PJB's Seriously Aeronautical Stuff
Jul 25, 2002, 05:57 PM
Peter K's Avatar
I tried several methods. Best is to start like SAL, but not so strong ...
Jul 25, 2002, 06:00 PM
Peter K's Avatar
in the air ...
Jul 25, 2002, 06:48 PM
Ascended Master
Sparky Paul's Avatar
Man, that thing looks like flying disorientation!
Betcha can't switch from a ZAGI to that one for the next flight!
I think that would make a good camera plane! Camera on the c.g. in a concerns about excess nose/tail weight.. Got any more dimensions?
Chords, sweep, c.g. location?
Jul 26, 2002, 02:35 AM
Peter K's Avatar
Here are the exact measurements:

WS: 109cm = 42.9"
Root chord (incl. rudder): 31 cm = 12.2"
Tip chord (incl. rudder) : 20 cm = 7,9"
Swept forward: 27,5cm = 10.8" (tip to root)
CG: ~ 18-19 cm = ~ 7.1"-7.5" (tip to CG)
Rudder: 50mm = 2"

Section is a modified SIPKILL ( -> profile -> S-Schlagprofile). The TE is modified to get a positive cm0. U can also use other flying-plank-sections such as phoenix, emx07,....

No washout!

If I would build the igaZ again, I would use 2 speed 400 6V instead of 300.

Last edited by Peter K; Jul 26, 2002 at 06:51 AM.
Jul 26, 2002, 01:04 PM
Ascended Master
Sparky Paul's Avatar
Peter, thanks... what is the motor location?
..scaling the inflight photo I get each motor is
30 cm out from the center...
Note.. for those interested.. "rudder" is "elevon" in this usage..
and check out Peter's link. Lots of information there..
Last edited by Sparky Paul; Jul 26, 2002 at 01:35 PM.
Jul 26, 2002, 01:57 PM
Peter K's Avatar
Yes, motor position is about 30 cm from center. On each side near the motors are 3 Cells, one cell is in the center. Rx (one on each side) and Hitec HS81MG near the tips.

Sorry for "rudder" instead of elevon (in Germany we say "Ruder" ...). Thx for information ).

Please note: Pic is from Inter-Ex 2002
Last edited by Peter K; Jul 26, 2002 at 02:04 PM.
Jul 26, 2002, 02:32 PM
RPV builder & operator
Pierre Audette's Avatar
Peter, is there any washout needed on this FSW design to make it fly, or is there enough inherent stability as is?
Jul 26, 2002, 03:04 PM
Peter K's Avatar
I designed the igaZ with no washout, but i used a flying-plank section with pos. cm0 for stabilization. I f u use negative cm0-sections, handling will be quite tricky and more critical.
Jul 26, 2002, 03:17 PM
Ascended Master
Sparky Paul's Avatar
I recently converted a ZAGI ripoff.. Phantasm.. to electric. Added a fuselage, verticals and a horizontal ala Wonder..Failed miserably.. then made it into a sloper. Failed worse!
The traditional response to sluggishness is moving the c.g. aft. But with a +Cmo section, if aft is more than 25%, Be careful.. be wery wery careful! It will not fly!
Also as Peter says, negative Cmo sections can be VERY critical in handling! Reflex of some amount will be needed unless it's a control-line..
Last edited by Sparky Paul; Jul 26, 2002 at 07:17 PM.
Jul 26, 2002, 03:42 PM
Peter K's Avatar
I did some conversions too. One of them is the batwing. Flies quite well .... Wings (of a Zagi-clone, but with a diff. section) only cutted 90 to LE, added a little fuselage and ready ...
Last edited by Peter K; Jul 26, 2002 at 03:51 PM.

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