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View Full Version : GWS Zero-Lessons Learned So Far


E-Challenged
10-12-2005, 04:24 PM
A friend bought the EPS 350 kit with motor/geardrive, I bought the unpainted no motor no landing gear version ( very cheap). I read all the forum threads I could find on mods and improvements. We both used carbon fiber rods in the wings instead of bamboo provided. The Zero is a typical short nosed radial engine scale model and avoiding tail heaviness is a real challenge.

The following "improvements" added to the tail heaviness problems and overall weight of ready to fly model:
1. Epoxied in a carbon fiber rod to stiffen and strengthen the stab.
2. Beefed up tailwheel pivot thing with a little piece of ply
1. Sanded everything smooth and filled holes in underside of wing and stab with model magic filler.
2. Painted the entire model with Minwax Polycrylic water base protectant to seal the foam. Glassed the ailerons for stiffness with 1/2 ounce fibreglass cloth and Polycrylic.
3. Airbrushed on craft store Forest Green and light gray acrylic water based craft paint.( I came out flat, no shine but attractive)
4. Noticed that the vertical stab tilted to the left, slit the foam and epoxied in a piece of 1/16 ply to make it vertical.
5. Used 5 Minute Epoxy through out.

I am using my MiniAC1215/16 brushless in a GWS C gearbox and 9" props.
I made landing gear legs from slightly larger diameter wire angled forward so that the wheel axles are ahead of wing leading edge. Total length of gear and wheels is 4 1/2" to allow adequate ground clearance for 9" props. It was necessary to Dremel out the battery compartment so that I could slide the Polyquest 1100 mah 3S lipo pack all the way through the firewall to the front of the cowl. I have the battery pack velcro strapped to the motor stick and around the front of pack attached to the firewall. I also molded the modelling clay provided into the sides of the cowl in front. The plane balances about 1/4 behind the spar. I did the mod where I lowered the wing's leading edge about 1/8" and raised the trailing edge to reduce wing incidence to handle the brushless power so that the balance should be about right. I filled in the fuselage/wing gap with foam board material sanded to fit. My model weighs 19 ounces ready to fly.

My friend with the stock EPS 350 Zero kit didn't like the "zits" etc and sanded and painted his model too. It also came out very tail heavy requiring him to mount his 8-cell AAA NiMh pack in front of the firewall.
His model weighs 20 ounces ready to fly and may not fly well with the stock motor and NiMh. We are both getting ready for maiden/trim flights which should be interesting.

Lessons learned: Don't sand and paint to avoid tail heaviness and overall heaviness. Don't do anything which adds weight from wing trailing edge to tail. The Zero doesn't really have enough battery pack room for larger packs needed with brushless power without major surgery which weakens the front of fuselage and motor mount area. It may be better to fly leave the Zero stock and fly it sedately with the 350 motor, etc than to doll it up and make it heavier and faster. Your mileage may vary.

Building, modifying and getting ready to fly the Zero was a almost as much work and head scratching as for a built up balsa model. Mine does look good/menacing in it's flat dark green and gray paint and all the shiny stickers.:D

PS: Just ordered the last two PQ 1100 3S lipo packs from Maxamps, CBP was out already. New 20C 1200 PQ packs will be sold only through Hobby Lobby and are too thick to fit the zero.

flypaper 2
10-12-2005, 08:24 PM
Everything you do is adding weight and takes away from the performance. Fibre glass, carbon fibre and acrylic are not needed. Use the GWS cement, works very well. Cut the batt compartment for the bigger batt. before you glue the two halves together. Paint right on the foam with Testors or water based paint with airbrush. I put in the carbon fibre spar two ins. longer than they show. Lasted two yrs. before the elevator servo crapped out. Try building a lightweight version to see the difference. I also cut the rear wing saddle down and put a bit more downthrust in the motor. Had a Himax 2025 2100 ma batt. would do 45 to 50 mph. A sweet flier.

Twmaster
10-12-2005, 11:03 PM
My Zero is awful at 15 ounces with a 350.

E-Challenged
10-13-2005, 09:09 PM
Taxi test and pre-maiden photos. Mine is Forest Green and friend Gene's is OD. His is stock except for paint, mine is geared brushless and lipo powered, both weigh 19 ounces. Battery packs protrude from firewall and needed ballast in front sides of cowl. Wish us rotsa ruck!:D

WWI Ace
10-14-2005, 12:55 AM
They look great guys, I just hope they don't fly like pigs!! I doubt the stock one will fly at all that heavy. Maybe it's just me, and I'm not trying to offend anyone but these are like $30-$50 airplanes. Fly them for what they are and have fun!! If they break, spend another $30 on a new one. I had a GWS Corsair with the 350. Built it bone stock except for airbrushing on some acrylic craft paint. It was my first warbird and I had a blast with it!! It certainly wasn't overpowered but it would fly. I have a slope glider version now that will eventually be brushless if the Alfa ever dies. I guess all I'm really saying is, don't make it harder than it has to be!!! Have fun!!

E-Challenged
10-19-2005, 09:41 PM
Lifted off normally into steady 10mph breeze then pointed nose sharply skyward , had to give it lots of down elevator, had one of the guys feed in some down trim, it settled down into scale-like flight at full throttle., not very fast. Did a barrel roll, not axial, flew around for about 5 minutes then 1100mah Lipo pack seemed to sag, so I landed. Bent one gear leg back a little. Lipo pack was barely warm upon landing. Next time I will add some clay inside the front of cowl and retrim. Elevator is in position where bottom of elevator and stab are even, top surface of elevator is slightly down. Used orange GWS Slow Flyer 9x4.7 prop, , will use APC 9X6 SF prop, should get more power/speed. Hoping 1100ma PQ 3S pack will perform better after two more 100mah slow break-in charges.

flypaper 2
10-19-2005, 10:09 PM
I put more downthrust in the motor for a 'climb under power ' condition. You'll be able to put more up trim in it without adding more weight. CG is not the problem.

Doppelganger
10-19-2005, 10:13 PM
If ever you build another foamie, use foam safe CA. Epoxy just adds weight. They may be 29.00 planes, but if built right, and with the correct mods, these planes fly very well. GWS has found a niche. Low cost aircraft that with a little help, fly very well. Plus, they give you the choice of whether or not to buy the power system with all of their aircraft. Unlike Ultrafly. I'd but more of Ultrafly's planes, but I know I'll just toss their power plant.

Great looking plane btw.:)

Steve

Doppelganger
10-19-2005, 10:18 PM
I put more downthrust in the motor for a 'climb under power ' condition. You'll be able to put more up trim in it without adding more weight. CG is not the problem.

I agree. Every GWS plane I've owned was built with extra downthrust. Then I trim them for level flight at 1/2 throttle. Makes landing approaches a breeze. Cut a little power and it's like being on a glide scope. It gently bleeds off altitude and with a little flare at the end...Voila!

Steve

E-Challenged
10-20-2005, 03:31 PM
Prop shaft is now more obviously downward pointing, should help. Plane flew well yesterday when elevator trim was set right, noticed that with one click more of down trim it wanted to shallow dive, this may be due to much reduced wing incidence. My Switchback 3D with symmetrical wing acted this way, had to be "on the step". The Zero glided (glid?) normally at low throttle for landing.

E-Challenged
10-21-2005, 09:36 PM
The Zero at 18.5 ounces, is a real sweetheart and flies very nicely and non-twitchty. Increasing down-thrust had little effect, still needs slight down trim. I switched from a 9x4.7 to a 9x6 prop for more thrust and speed. It now ROG's in about 15 feet, will fly slow and scale-like or like a fairlyhot aerobatic scale model. It'll climb vertical to about 300 feet and then hover for a while before falling off on a wing, very easy to pull out of a spiral dive etc. It will fly inverted with down elevator. Rolls are
barrel-like requiring down elevator when inverted because of all-up and no down aileron action as currently set up. This aileron set-up gives very
smooth turns with no adverse yaw but rolls are slow and barrel-like, not
axial, like the real thing. The power at full throttle is such that you can
do any number of loops from level flight. I heard some aileron flutter in
full throttle dives. Landings, with flare, power on or off are easy without
even bending the wire gear. With the 1100mah PQ 3cell lipo packs, flight times are ten+ minutes with lots of wide open throttle flying and landing with lots of charge left. I recharged one pack after a typical flight and it only took 600ma and charged in around 45 minutes at 1.1amp off my field box battery. The MiniAC 1215/16 in GWS gearbox with 9x6 GWS SF prop is only pulling around 8 amps at full throttle, so the little 1100mah 3S lipoly slid all the way to the front of the cowl is a good match.

E-Challenged
11-02-2005, 08:57 PM
I installed one Radio Shack magnet on each side of fuselage and tin can strips epoxied to insides of canopy. Held on great for about ten flights , then fluttered away and landed in the deep bushes and weeds.

I should have put two magnets on each side of fuselage.

I will install velcro strips instead on next canopy . BTW, plane seemed to fly less smoothly with canopy missing.

I just bought the Spitfire kit, these GWS foamies are like eating potato chips. The Spit has a much more secure canopy/battery hatch attachment method.:D

qban_flyer
11-02-2005, 09:49 PM
My Zero has just been fitted with a Great Planes 370 motor, geared 5 to 1 on its stick mount. It is the same sort of affair I have on my G/P Flat-Out 3D models. A Great Planes C-12 ESC takes care of the power distribution and Thunder Power 11.1V 900s take care of the e-juice. Propeller is a 9X3.8SF APC. BTW, the T/P 11.1V 900s fit in the factory battery pocket like "hand in glove".

AUW is 13.5 ounces ready to roll and it balances right on the money. Although I flew twmaster's GWS Zero a couple of weeks ago and found it terribly underpowered and rather "pitchy", I believe the lack of power and that extra 1.5 ounces of weight were detrimental to its flight characteristics. It flew as if on the verge of a perennial stall.

The power plant I now have on mine has been tested and proven to be capable of flying much heavier models than the Zero (those other models weighed in at over 16 ounces), and they were handled with "gusto" by the G/P Flat-Out 370 power plant.

The trick with these GWS foamy warbirds is to first and foremost get rid of the stock powerplant. Assemble them together in as light a manner as possible, and to use Li-Pos if you possibly can. A brushless motor would improve things quite a bit more over to what I am now using. Lightweight components, adhesives and coloring will go a long ways to making the GWS Zero a very capable flying model.

qban_flyer
11-02-2005, 09:54 PM
Taxi test and pre-maiden photos. Mine is Forest Green and friend Gene's is OD. His is stock except for paint, mine is geared brushless and lipo powered, both weigh 19 ounces. Battery packs protrude from firewall and needed ballast in front sides of cowl. Wish us rotsa ruck!:D

Nice looking Zeros!!!

E-Challenged
11-13-2005, 08:39 PM
His flew like doo-doo on the stock geared 350 and 8 cell Nimh pack. He bit the bullet and installed a Himax 2015-4200 and 3S 1320mah Lipo and now it's flying great just like mine only his has stock wing incidence and weighs a little more. He has since ordered an AXI 2212/26 and is wondering what to do with all those round cell packs just like me.:)

flypaper 2
11-14-2005, 12:35 AM
Just gave mine to a young lad that couldn't afford lipos. He looks like this :p

qban_flyer
11-14-2005, 01:17 AM
and is wondering what to do with all those round cell packs just like me.:)

I donated all my non Li-Po packs to the Salvation Army along with two chargers, and a few models and radios I was no longer using. You should have seen their faces when they took the "stuff" in. :D

mechrick
11-19-2005, 03:49 AM
Still flying my Zero dead stock after about 8 months. 350B with a 9070 prop and 8 cell AAA NiMH. After a few crashes learning ailerons (graduating from a Parkzone Cub modified to add ailerons) I found the secret for keeping my Zero flying - keep the nose down and speed up in turns.

The bad angle of attack wing, unequal fuselage (one side 1/2 inch shorter), left bending vertical stabilizer, tail heaviness, and just enough power to take off make it a challenge to fly initially. But I am now used to it and find it quite easy to put through loops and rolls and deadstick or power on landings. I had to push the battery about an inch forward of the fuselage, aganst the cowl, to balance it properly.

I actually like puttering around with the setup stock. Of my 5 planes it is my "safe" one. I know better battery and motor would give me power to get out of trouble, but I like that the plane has to fly on the wings and not the prop; I believe that will make me a better pilot in the long run.

Rick

qban_flyer
11-19-2005, 06:01 AM
I actually like puttering around with the setup stock. Of my 5 planes it is my "safe" one. I know better battery and motor would give me power to get out of trouble, but I like that the plane has to fly on the wings and not the prop; I believe that will make me a better pilot in the long run.

Rick

I noticed you have rudder on yours. I just might do that to mine too. Though I don't really need rudder correction on take off, it would be nice to be ale to spin and snap roll it.

I love mine. It takes off in less than ten feet, climbs fast and rather steeply. My favorite thing to do with it is to buzz-by at full throttle after a 200' dive! What a thrill. :D

mechrick
11-19-2005, 05:58 PM
I noticed you have rudder on yours. I just might do that to mine too. Though I don't really need rudder correction on take off, it would be nice to be ale to spin and snap roll it.


I don't use the rudder much in the air, maybe to straighen out a landing in a cross wind. I have not learned to use it in turns or axial rolls, but I can do a nice stall turn or wing over. I do use it a lost on the ground - I love to taxi out onto the runway and take off, then after landing taxi back to my feet. To me half the fun and challenge is taking off and landing. And I'm lazy...;)

Rick

Trexzation
01-08-2007, 02:25 AM
Guys,do you think a tower pro 2409 Bell type BL motor is adequate for the zeros? thanks

CHELLIE
01-08-2007, 02:43 AM
Guys,do you think a tower pro 2409 Bell type BL motor is adequate for the zeros? thanks

Hi, The 2409-12 is the Ultimate GWS motor, I am building a F4U Corsair and thats what is going in it, with a 9x5 prop and a 30 amp ESC, 1500 mah 11.1v lipo. that will give you 33 oz of thrust :)
http://cgi.ebay.com/2409-12T-Outrunner-Brushless-Electric-Motor_W0QQitemZ220068729013QQihZ012QQcategoryZ3405 6QQcmdZViewItem
Take care and have fun , Chellie

ps The 2409-12 has the same power as a OS LA 15 glow engine
http://www.himodel.com/electric/Tower_pro_Outrunner_Brushless_Motor_Type_2409-12.php