Formosa Rocks!

[Marc Humphries]

Hi folks - I threw a Formosa together as a way to get me back into RC flying after a gap of 12 years or so. I initially flew it stock with a 2S 800 Lipo. It flew like it was on rails, though a little slow. Since it was my first real aileron model it suited me just fine. As an aerobatic trainer I can't think of how you could spend a better £20 or so. When it was time to pep things up, an email to Brian Collins resulted in a 120W power set up being recommended. http://www.brchobbies.com/?page=shop&action=additem&item=80.

Just had it's first flight this morning on this set up with a GWS 7 x 6 and a FlightPower 3S 1200 Lipo - working from home does have it's advantages...

Wow! The little Formosa is transformed! More or less unlimited vertical performance but still retaining it's rock steady characteristics. Got over 12 minutes on this set up and the noise from the motor/prop has a quiet growl - sounds like a very well muffled 4 stroke. Great stuff!

[Danny Fenton]

Hi Marc which Formosa is it? the Mk 1 or II? also what sort of wattage are you pulling?
Mine is on order but hasn't arrived yet. Flew a friends Formosa Mk1 last Saturday and was very impressed, flys like a much bigger model and goes where it is pointed. Haven't built a foamie before so a bit nervous about glues and hinge materials, may need to ask your advice if the postie ever delivers it LOL

[Marc Humphries]

Hi Danny - I've got the cheapo Mk1. It's flying on around 120 watts at the mo and with that power it has a very sprightly performance. I chickened out of the vertical climb when it was getting a little too small for comfort! As my post says - even on the stock motor and gearbox it flies well. Consecutive rolls, loops from level flight, multiple cuban 8s - it's all there for you if you are fairly new to aerobatics.

As for building the thing - it's pretty easy but there are a few gottchas. First Glue. GWS supply a foam glue that always takes ages to set. I personnally find that a medium thickness foam safe cyano used with a kicker spray works very well. Epoxy also works well for the higher stress areas.

Then hinges. You have to cut out all control surfaces from the wings, tailplane etc - bevel them and then hinge them. I mislaid the supplied hinges and had to use mini pinned hinges. These were a nightmare to slot into the foam and even more difficult to glue in without them binding. My fault though!

I didn't fit the undercarriage - as hand launching in easy and it saves constant damage to the gear and saves weight.

With the stock motor I used a 2S 800 Li-Po which gave me all the performance I wanted as an aileron and aerobat trainer. I used this set up last season. With three battery packs I can have three 10-12 minute flights in one hour at my local park or sports field.

I only had one crash - caused by selecting the wrong model memory on the transmitter. It crashed immediately after launch and snapped the fuselage in half just behind the wing. A few minutes in the garage with cyano had it almost as good as new.

You'll have great fun with this little model. Probably the most fun you can have for £20 - apart from a subscription to The Fantasy Channel!!! ;-)

[Danny Fenton]

Thanks for that Marc, I wont bother with the undercarriage either. I have heard that old floppy disks cut up provide excellent hinge material, I was going to try that. I have read that fuselages tend to warp after joining and to run them under hot water while holding them straight sorts it, did you come across this? I have ordered some foam friendly CA as it will be quicker than waiting for the GWS glue. I have a 130watt setup with a 1500Mah 3 cell lipo ready to go in, so should go very well. How does yours handle stronger winds, I fly at a fairly windy field?

[Marc Humphries]

I had no problems with warping or anything like that.

Your power setup sound fine - it will really go well with out being silly!

I've flown it in 10-15mph winds. It copes very well - haven't tried it in anything stronger.

There's a strong Formosa thread on RCUniverse. Health warning: Our American friends do like to over analyse and complicate things.

[Danny Fenton]

Should be working but I suppose a quick web browse won't hurt LOL, thanks Marc

[Danny Fenton]

Well the Formosa arrived this afternoon, what with work I couldn't get cracking til about 8pm tonight. Tried to get the foam friendly CA to glue foam, would it heck! after 5 minutes it was still just a damp area between two bits of foam. The brand is Vital Bond and has a white cap. Had to use the GWS glue, which is still not dry after more than two hours. Oh well, saying that it is over half finished LOL turned to 5 minute epoxy. Still cannot find a method of giving foam some color though, the stickers are a bit tacky, scuse the pun.

[Mike Rolls]

If the Formosa is the same sort of foam as their warbirds - mine is a Zero - ordinary household emulsion works fine. So do acrylic paints from art shops.
HTH

Mike

[Danny Fenton]

Thanks Mike, I popped into my local model shop, and found an acrylic aerosol, RC Styro Colours, looks just the ticket, I will let you know how it goes on. I searched the web and J Perkins do it:

http://www.jperkinsdistribution.co.uk/list.php?subcat=111&cat=Sprays%20-%20Styro%20Colours&Navmain=Paints,%20Dope,%20Brushes

[Danny Fenton]

Well it covers well, but it does feel as though the paint has added a fair bit of weight. The trouble with foam is when you sand it to get rid of the moulding marks it scratches the surface which then accepts paint in a different way to the areas un touched by sanding. The end result is a somewhat mottled finish. I should have weighed the model before applying the finish as I am sure there must be a fair weight penalty. I kinda wish I hadn't bothered, well you live and learn as they say.

[Mike Rolls]

Danny
The way I did the Zero was to buy these little 'tester' pots of emulsion and brush on - brushing out really well. Two thin coats covered OK with no noticeable weight increase (didn't actually do a 'before and after' on the scales, though. I didn't sand first as I anticipated the sort of patchiness to whihc you refer - so th efinish is a bit 'stand well off' but OK for purpose.
Mike

[Danny Fenton]

Thanks Mike, it is all a big learning curve for me. I am familiar with all the old ways, but this is totally new to me, which is fun.

[Mike Rolls]

Danny
You and me both - I cut my teeth on tissue/dope and banana oil!

Mike

[Danny Fenton]

Stop! you are making me feel old, somebody was running a diesel at the field last Saturday and I had to go and sniff the fuel, it bought back so many childhood memories of us trying to master control line LOL You don't suppose one day we will wake up and suddenly find we have grown up do you? I hope not....

[Steve Hargreaves - Moderator]

Probably a bit late to mention this but I found UHU POR to work well on foam but spread it thinly & use it almost like a contact adhesive or else it can take a while to dry.

Two other points...cut the rudder & elevator control tubes longer than the 370mm specified. at 370mm you can't see the ends & that makes it hellish difficult to get the wire in. Go for 385mm & be happy. Second point....make the canopy mount a bit stronger or you'll be forever wandering off to find it. It comes off after any particularly exuberent manouever....knife edge always did mine for some reason!!!

Other than that the Formosa is an awesome machine....120-130watts is perfect & although not fast it is very precise & just goes where you point it....I love mine even though it has been crashed several times & looks a bit tatty...I just can't stop flying it....as someone said the best £20 you could spend

[Danny Fenton]

Hi Steve thanks for the tips, unfortunately mine is now ready to fly, and you are right those control tubes were too short, but they have worked fine. I will have to see what happens re the canopy LOL. Another tip worth mentioning is to hollow out the fuselage to accept the LiPo pack you are intending to use before joining the two halves, I would imagine it would be a sod afterwards. Also the excess elevator/rudder cable outer use them to extend the aileron and elevator piano wire right into the control surfaces, stiffens them and gives more precise control. I only have a 7x5 prop at the moment this gives 113 watts @ 10.4 Amps, the model weighs in at 446g. I will source an 8x4 and 9x4 to up the power slightly, as it is a low Kv motor it really needs a bigger prop. I will let you know how it goes :)

[Marc Humphries]

Jeez Danny - you only got the thing Friday lunchtime! Nice one!

[Danny Fenton]

Hi Marc wondered where you got to LOL Unfortunately the flaming GWS glue took forever to dry, tried using some foam friendly CA but it wouldn't go off! guess you need some sort of activator when glueing foam, when I realised how long the GWS stuff was taking resorted to using 5 min epoxy. Otherwise would have been ready to test fly with the Tucano this morning (before the rain and winds took hold). Had a bit of trouble making an accurate adaptor plate to convert from stick mount motor to Radial Brushless. Also had to dismantle the motor and reverse the shaft so that it would mount with the bulkhead behind the motor. Started a scratch Hurricane this afternoon LOL got some catching up to do, been out of the hobby for a few years, and the hanger is looking a little empty, can't have that can we LOL

[GrumpyGnome]

For the next build, or repairs ............. :-( treat the GWS glue like UHU POR - its a pretty decent contact adhesive. I've built a few GWS warbirds and it took me a couple to cotton on to this.

I never bothered sanding the pimples off - can't see them when the planes are flying anyway. I painted mine with Tamiya acrylics, brushed on.

GG

[Marc Humphries]

Had a bit of trouble making an accurate adaptor plate to convert from stick mount motor to Radial Brushless

My motor came from BRC Hobbies and they supply a GWS stick mount that the motor backplate screws into. Really simple. http://www.brchobbies.com/?page=shop&action=additem&item=80.

Wrt glues - cyano on foam does need a kicker spray - and then it's really quick and effective. Good luck with building up the hanger.

That's one thing I have noticed since returning to the hobby. I have five planes all in a flight ready condition - complete with receivers, servos etc. This would have been unheard of 15-20 years ago!

[Danny Fenton]

Hi Marc, yes I saw those stick mounts but they only seemed to come in a bundle with that motor, I already have the motor and ESC. Anyway it didn't really take that long to make. Thanks for the advice on the glue, I will know next time.

[Danny Fenton]

Well... with the wattmeter I am getting 125 Watts, 12.4 Amps with a 8x4. The motor is rated at 9A continuous 10 sec bursts to 14A, the controller is a 18A-22A I could try a 9x4 but really think I am just about at the limit of the motor. The spec sheet suggested an 8x4 would give 140 Watts, I am falling short of those figures (tolerances perhaps?). Of course the motor will unload in the air, and I wont be flying at full throttle all the time. Do you guys "that can tune the smoke", think this will be entertaining enough?

[Marc Humphries]

You're flying at around 130W per pound. That should give the Formosa a very nice field to play in! Good luck...

[Steve Hargreaves - Moderator]

As Marc sez 130W per pound will be pretty entertaining so I'd stick with the 8x4 but as you say keep full throttle to a minimum

I assume the fact you are slightly below the 140w mark mentioned is because your battery voltage is dropping off slightly at full load....a 3S LiPo is nominally 11.1 volts & we usually assume about 10V under load so 10 x yer current gives the watts hence the 125 watts. If your battery could hold 11.1 volts then 11.1 x 12.4 = 137.64 watts so maybe the 140 watts is a theoretical value

Did you say what size battery you're using?? My personal rule of thumb is not to exceed 10C so for 12.5amps you'd be looking at a 1250mah (minimum) Lipo...preferably a bit bigger like a 1500 or 1800....

Just fly it before changing anything but I suspect you'll need a new motor if you want to get more performance. Mind you see opening comment...at 130Watts you'll be pretty happy!!!

[Danny Fenton]

Hi Chaps, thanks for all the comments. Steve the battery is a FlightPower 25C 1500 Mah and really should have delivered more punch. I test flew it tonight and apart from three clicks of up, (which I cannot understand as the model balances on the money, Could be thrust angles though LOL) It flew straight otherwise. Would loop from level flight, rolls were pretty axial, but vertically it was challenged from level flight into vertical I could only get a half roll, I dare say with a bit of a dive first, a full roll. But speed is not what the model is about. It flew very precisely, and inverted flight was pretty good. My main concern is that the pack should have lasted much longer. As it was it faded after 5 minutes of 1/2 - 2/3 throttle, with the occasional full power burst. The pack is nearly new having only been cycled 3 times. But all in all a very succesful flight. My friends Formosa, which I flew last week is delivering 171 Watts and really does perform well. As you say Steve, and I agree I think I am on the limit of this motor, but cannot understand the pack fading so badly after just 5 mins. It took 50 mins to recharge by the way.