Well I finally just about got it done and it's time to balance it. I have a OS 108 for power and I tried balancing it at the 152mm and to get it about 160 mm I have to add 2 - 1800 5cell batteries to the fire wall, about 1.3 pounds worth, plus add the reciever to the front some how.

Does this sound about right or how far back can I go with the CG?

FYI, right now with out the balast it weighs 10# 10 oz.

Zeros with scale proportions always need lots of weight to balance. Short nose.

I moved everything as far forward a possible. I made a bracket to mount the battery in the cowl. Mine balances at 145mm. Its a great flying plane, very responsive. It does not slow down on landing so I installed flaps. Just put two flights on it yesterday. Really sweet. I also installed Robart air retracts. I am going to put 3.5 inch wheels in it. Stock just look to small and I fly off grass. Mine is about 11 pounds and has a very slow gentle stall.

I fly at 1/2 throttle with a 108 and 15x6 APC. I think a Saito 100 or OS 91fx would be fine. There are some other threads in ARF if you do a search.

I hate the paint though.

I test flew mine at 152 mm CG. It flew, but level flight requires 10 deg of down elevator. Landing also balloons quite easily, however will not result in an adverse stall. It will eventually settle down in a harrier manner: not how I want to land a warbird though. I have since moved my YS 120 forward by 1/2", so spinner is a bit forward out of the cowl. Now the balance is at 145 mm.

I think 160 mm CG will be asking for trouble. Try getting heavy propeller (MA Classic 16x6 or APC, 2 oz more), larger, heavier spinner (Pro Spin or Dave Brown 3.25", 2 oz more), and spinner nose weight (2 oz max), as they are the most effective ballast. Next, try to get a heavy Pitts muffler for your 108. I have a spare JTec pitts for the 108 that must weighs 10+ oz (5 oz heavier than BCM), if you want to try it let me know. Next, get a heavy metal motor mount like those that came with the EZ 60 size ARF's. They weigh a good 5~6 oz instead of the 3 oz stock mount.

To move the CG from 160 mm to 145 mm on a 11 lb. plane, you need 15mm x 11 lb = 165 mm-lb (or 104 inch-oz) of moment at the nose.
Assuming your spinner is 13" away from current CG, your spinner ballasts will contribute 13" x 4 oz = 52 inch-oz of nose moment.
Assuming your muffler is 10" away from current CG, an additional 5 oz from heavy muffler and mount will contribute 10" x 5 oz = 50 inch-oz of nose moment.
These will get you close to 145 mm of CG.

I wouldn't put the functioning battery pack to the cowl, because one of my friends helicopter w/ battery on his canopy flew away when the canopy fell off along with the battery, all while during an ascending spiral. It just kept flying higher and further away. They never found it.

I personally feel that OS 108, or even 91 2-stroke, is way too light of an engine for this plane. I feel it's irresponsible for a manufacture to list a 91 2-stroke without stating in the instruction that kg's of dead weight needs to be added to the front. It's kind of saying "tough". Anyway, good luck!

Well time for a bigger engine then. I was going to stick a G-23 in it but I cut the cowl up for the side mount engine so I have to live with that now. Hmmmm.....I seen a OS 1.6 here somewhere, maybe that will be enough weight.

OS 160 is a great choice.

Dave Platt has a 80" Zero at 15 pounds with a battery box under the upright motor. Its a proven design with a OS 108 for power. He states it flys well at 22 pounds using a bigger motor. Mine flys much faster than scale with the os 108. This is at sea level, if you are in the mountains of course more motor is needed. If you use common sense to secure the battery you don't have to add lead at all. I hate dead weight more than anything. A OS 160 is way over powered for this plane. Of course if you want a 3D Zero to circle the Moon please feel free to do it.

Carl

Well, with OS 160 FX you get the benefit of swinging the Graupner 16x8 3-blade prop for that cool look factor.

I agree that 108 is plenty power for warbird this size. I had a 108 that's on-par w/ my YS 120 in power. I just think it's too light to balance this plane. I also don't like putting battery too close to the engine because of the vibration, not that I've killed batteries this way. Just personal preference.

Regarding dead weight though, this plane has really light wing loading for its size (even lighter than some of my 120 size aerobats). Adding some weight will actually make it land more scale like, if it rhymes with you.

Personally, I feel the best engine for this plane would've been the Saito 170 3-cylinder. Oh that 3-cylinder sound… Too bad it doesn't fit in the cowl. Believe me, I really want to make it happen, but I got some template for the 170, and the cowl will have 6 golden valve covers protruding...

I have the same ZERO,I use a Webra 1.20.
Great power.
Yes I had to add about 13 oz.`s to the nose.
Flys great but the struts are way too long on this Zero.

Oh my the Saito 170. That would be the cats meow. I think it would fit in the Platt Zero if built light. I plan to do the Platt Zero next year and will over power that with the OS 160FX, the Webra 120 or Moki 135 might be better choices but I have the OS needing a home. I will try some scale detail and hopefully under 20 pounds.

I think there is six of ounces difference between the 108 Weight: 750g (26.5 oz)and 160 930g (32.8oz). I guess that is my battery pack.

The Webra 120 is a very powerful motor. I have one in a Stinger (when it dies I hope to put it in a DPM Ultimate) and its great but will not quite hoover the 12-13 pound plane. I shortened the landing gear about one inch looks better. Now for bigger wheels.

I wish Saito would make a 3 cyl 240 or so. I have the 450 and it sounds so wonderful.

cool weathering, cant wait to see it in person. Let me know when you go!

Thanks for the input guys.

Hi Carlbecker,

I read in your previous post that you mentioned you installed flaps on this plane. Was this difficult to do? How did they turn out? Can you provide details, and of course pictures would be great!

Thanks,

Its not hard to do. I just penciled in the area to be flaps and cut out the area. Find a 3-view for refference. Trim down the ribs and add stock for hinge mounts. I made the flaps from thin ply with light fiberglass and epoxy on each side. I used Robart hinges and set them at a 90 degree angle when the flaps are closed. Hitec 225's mounted close the the cg. The Zero balloons up when first applied. I have added some down trim to the elevator but not flown since. Probably added 6 ounces total weight or less.

Carl

Hi Carl,

Thanks for the info. Did you do a split type of flap like the "real" plane, or are these full flaps? Not sure I'm familar with the Robart hinges. Are you talking about the "Robart Hinge Points"? Why set them at 90 degrees when closed? I've attached a pic I found and modified which I think is sort of what you are describing. Let me know if I'm in the ballpark with this one.


I think I will fly it without them first, but I am considering putting a Zenoah G26 on the nose and I believe that will make it on the heavy side and expect landings to be rather fast. The flaps are probably going to be a necessity.

Thanks again,

Yes that is about what I did. The hinge points are out in the air flow like the flaps on a Grumman Wildcat as is the horn. Not sure how the real flaps work but I have had success with this method. When the flaps are fully deployed the hinge is almost straight. Since this is an ARF I just did the servos like the ailerons. It was a quick and dirty job as I had pulled the retracts out while landing and now the bottom shows repairs. They work really well on the two flights I have tried. A G26 is way to much motor for me on this plane and I would guess you will really need flaps. Mine is 11 pounds or so and really likes to float, I had to idle before final and had a long approach-not now. I kept the tail as light as possible, used carbon rods and put everything as far forward as possible. Just a little lead (1 oz) in the front. I can do decent vertical and big loops with a OS108. Flying at 1/2 throttle looks about scale. At about 1/6 scale max speed should be about 65 mph? Anyway it grooves well. If I had time I would get rid of that poor paint and glass the wing.

Carl