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Flying the GWS Formosa

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Formosa

Formosa

Nigel Hawes reviews the GWS kit - 28/10/10

Colin Naylar19/03/2009 18:01:01
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231 forum posts
16 photos
Hi All,
I've just taken my GWS Formosa out for it's maiden flight and thankfully brought it back in one piece. Its my first aerobatic plane, tho' I have flown ailerons and low wing before on trainers. The Formosa is running a 125W outrunner on 3s Lipo with a 9x4 prop and the CofG is 90mm back from the leading edge. All control surfaces are on minimal throw as I didn't know what to expect.
   On a hand launch at full power she fles straight up almost but straight as a die so I brought her back to about half throttle and puttered about quite happily. With any application of more power she seemed to balloon upwards which I trimmed out with a bit of down elevator. On cutting the throttle she came down quite fast which I am also concerned about as without power she is supposed to be a slope glider. So, help please, is this normal behaviour for the Formosa? My initial temptation is to move the CofG forward to correct the ballooning, but what about the glide - or ain't it supposed to?
   To be honest I am very pleased with it (and myself) and I had a great seven minute flight, but I could do with a bit of help to sort these problems out before I go out for another flight.
Cheers Colin

Edited By Colin Naylar on 19/03/2009 18:18:46

ken anderson.19/03/2009 18:08:45
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8497 forum posts
773 photos
hello colin i've had formosa's-neither was like you discribe when flying--it sounds like a c/g issue--with the gws models being so lightweight to start with the c/g is critical in that a slight forward or back  c/g makes an immediate difference--sounds like yours is tail heavy-when sorted you should find it'll glide no prob's-good little model =load's of fun.......................
 
            ken anderson..............
Martin Harris19/03/2009 18:13:34
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9024 forum posts
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Sounds like you might need to add some downthrust.  Once you've trimmed it with some down elevator under power then on the glide it will tend to drop its nose and build up speed quickly if the thrustline is too high.
 
I last flew mine on NiMHs so I suspect yours won't be any heavier but you didn't say what size pack you're using.
 
I've slope soared in a gentle breeze without difficulty (motor installed but not needed) so the glide shouldn't give you any problem.
 
The C of G won't have much relevence to this problem.  A rearward position will make it pitch sensitive but not the symptoms you've described.   I can't remember wher my C of G was but just go with the position in the instructioons and you shouldn't have any problems there.

Edited By Martin Harris on 19/03/2009 18:17:13

Colin Naylar19/03/2009 18:27:40
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231 forum posts
16 photos
Thanks Ken and Martin, as I said my inclination is to move the CofG forward but it actually is at the forward limit of it's range already. Perhaps you have the answer Martin - I shall obviously have to do some very gradual experimentation. Fantastic machine at the price!
 
Anyone currently flying a Formosa? - I'd be interested in your CogG if poss please.
Thanks again
Colin
buster prop03/03/2010 20:39:00
482 forum posts
12 photos
I maidened my refurbed Formosa yesterday which was a rare calm day at the field. I was given the plane as a tatty airframe only. With the CG at 90mm back from the l.e. it seemed slightly tail heavy. It was ok but difficult to fly level, seemed to want to pitch up and down. 2S enough for me, for next flight will have a 10g weight stuck onto the motor mount which has moved the CG forward by about 5mm. I think Formosas are great fun for the price even if you buy one! I'll let you know how it goes.
Andy Gates03/03/2010 22:58:03
636 forum posts
19 photos
I would go with martin and add a little more downthrust to the motor.
 
This should be easily achieved by adding a couple of washers behind the motor mount to the 2 top screws only.
That really should be enough.
ken anderson.04/03/2010 07:42:59
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8497 forum posts
773 photos
hello buster - what you describe(pitching up and down).......sounds like tail heavy for sureo.....add some lead to the beak and gradually reduce it until the model behaves the way you feel happy with.......
 
    ken anderson.
buster prop04/03/2010 17:52:28
482 forum posts
12 photos
Hi Ken. That's what I thought as well, 10 Grams might be too much, C of g is a bit of a preference. Personally I feel comfortable with it a slightly forward until I'm used to the plane and then try moving it back, slightly.
Buster.
Andy Gates04/03/2010 18:21:13
636 forum posts
19 photos
Ken
 
Please reread the origional post.
 
The plane is not suffering pitching issues since it is steady under fixed power.
It is the variation of power which is causing the trim change which suggests it is a motor alignment issue rather than stabillity.
Colin Naylar04/03/2010 19:38:04
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231 forum posts
16 photos
Hi guys, I wrote the first post so I thought I'd better tell you how I sorted my Formosa out. Its still flying and I've had tremendous fun with it over the past year. First of all I added about 2 degrees downthrust to the motor which improved things a lot. It still wasn't happy on the glide though so I then swapped the battery to a 2s 1000mAh and changed  the prop  to a 8" x 6". The  c of g is still at 90mm and she flies great for me. The AUW is 510g, the power used is 80W and the wing loading is a fraction over 10oz/sq ft.
Lee Smalley04/03/2010 20:16:37
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2125 forum posts
68 photos
2 articles
guys there is a good piece on the home page of this site about trimming your aeroplane and how to sort out if it has a rear c of g or the right side thrust, i recommend that everyone read it! it makes sorting your new toy out very easy 
Andy Gates05/03/2010 17:07:47
636 forum posts
19 photos
Glad you got it sorted Colin, now have fun with her.
buster prop04/04/2010 20:47:04
482 forum posts
12 photos
Flown my Formosa 1 with CG moved forward, much better! Only problem was that I used an old Flightpower 2S pack which shows about 90W at first but quickly drops to about 70W because its voltage sinks to around 6V. I was worried about a brownout as I'm using a Spektrum receiver so I bought a Dualsky 30C 1200 2S pack and that shows about 110W on the same prop and holds up its voltage better. The Formosa has a 2212/10 motor and a 9 x 4 prop. Want to fly it again when the wind drops and it stops raining.  
Tim Mackey04/04/2010 21:24:30
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20920 forum posts
304 photos
15 articles
If you ever get the voltage of a 2s Lipo low enough to cause a brown out...then the pack is goosed. Brown out will not occur until you are way down around 3V or so
buster prop05/04/2010 21:49:16
482 forum posts
12 photos
Thanks Timbo. I think my old Flightpower pack was past it, shown by the fact that the new battery holds up its voltage much better on the same load. This is why Wattmeters are so useful. I agree that Spektrum receivers should work from below 6 volts input from the BEC but don't know what the BEC supplies when the battery voltage gets too low. I read a scary warning about Spektrum brownout elsewhere in this forum but that's not the main reason why I replaced the battery.
Tim Mackey05/04/2010 22:19:18
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20920 forum posts
304 photos
15 articles
The Bec should still be suppying a constant 5v even when the supply battery is down around 6V - which is below the LVC of the spoeed controller anyway.
buster prop10/04/2010 19:59:13
482 forum posts
12 photos
Sunny warm weather and light winds at last! With the new battery and its slightly forward CG my Formosa flies brilliantly! Bags of power, 2/3 throttle plenty for me. A lot of people at the field this morning lets hope for more of this in 2010, 2 flights with Formosa and 2 with another plane.

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