hookedonrc

I just finished my new Funtana and am ready to balance. I have never had a mid wing plane before. On this particular plane, do you balance with it inverted or top side up?

Doc Halliday

Hey hooked, what field do you fly at.I fly at TGD

hookedonrc

I am at American Turfflyers out east. If you know where that is. BTW we are having a fun fly tomorrow if you are interested in coming out. Entry fee is $8.00 and it includes lunch. (Hamburgers, Hot Dogs, etc.) Events are: Bean Carry, Fly and Glide, Prop Buster, and limbo. I am not going to use my Funtana if that's what you might be thinking. I have an Avistar Trainer and will use that. It will be my first funfly with events.

hroachen

I did mine inverted, seemed to work out okay. I didn't even try to set it on the CG machine upright so I couldn't say if that would work out. I think it's closer to a low wing than a true midwing, so inverted looked like the way to go.

D

hookedonrc

Thanks hroachen. That's what I ultimately have decided to do. However, you are probably better off for not using the CG machine. On the machine it is very very touchy. Whether it is inverted or I place on the machine right side up (guess right side up is an oxymoron for a aerobatic plane) it drops the nose. I will spend some time on it today after work. In any case, it appears difficult to balance.

hookedonrc

Oops, reread my response and it sounds like it is nose heavy and needs weight in the tail. Not so...it is just that it gets very close to the balance point and just a little change in the weight distribution it swings through nose down. Whether it is upside down or not. BTW it does have the SAITO 72 on it.

hroachen

Yeah I don't think this plane will want to sit level on the machine, but I got it where it felt like it could fall either way and felt that was good enough. I think I might shift some weight rearward, it flies just a wee bit nose heavy now and when I get the cowl on I'll want to offset the extra bit of noseweight.

D

TailTwister

My Feedback: (1)

Many aerobats have a CG that brings the vertical axis near the centerline of the plane's wing. That makes it hard to use a balancer. Just look for an easy likelyhood that it could fall either way.

Keeping the vertical GC near center means that the plane will hang closer to vertical in a stationary hover or torque roll. For example, most Caps require the plane be on it's back to torque. The Funtana (and most Edge 540s) do not. It hangs almost straight up and down.

hookedonrc

Thanks TailTwister. Based on what you have said, I am probably right on now. However, before assuming it, I will put it on the balancer one more time. As I remember, the tail wanted to fall as much as the nose when I had it real close. I bet I am right on. I have heard that the SAITO 72 is exactly right weight to balance the plane, or at least very very close.

TailTwister

My Feedback: (1)

I put my 600 mah 5 cell nicad just behind the fuel tank, and I believe I'm just a hair on the nose heavy side for my taste. I plan to move the battery to the suggested place and fly it again. My balancer made me believe I'm somewhere between 5 1/2 inches and 5 11/16 inches. When I'm not 100% sure of the exact measurement, due to the vertical CG, I do a go/no go type of thing. At 5 1/2, the tail falls 100% of the time, and at 5 11/16, the nose falls 100% of the time. I'm 100% sure I'm between the two.

TerryPhillips

My Feedback: (1)

I've been using my digital scales to balance my planes. I build 2 triangle frames from cardboard (1 guess where it came from). The height differs from each other to compensate for the digital scale and the fuse taper. With the stab level, the rear of the fuse is about 3/4" higher than the front pivot point located right in front of the LG. I mark the rear point with a sharpie across the fuse 36" back from the front point. The distance is not critical, you just have to know what it is. Think of this dimension as the "wheelbase".

Ok to get a balance on my H9 Funtana:
1. Take a total weight of the plane. 2460g
2. Set plane on front pivot.
3. Zero scale with rear pivot.
4. Slide scale and rear pivot under tail, align with mark.
5. Take Rear weight. 413g

The Math:
rear/total = weight distribution %
weight distribution % * wheelbase giveswheelbase CG.
Subtract offset of front pivot point to LE of wing (1/2" in my case) for a relative Wing CG.

413/2460 = 0.1679 weight distribution %
0.1679*36" = 6-1/16" Wheelbase CG
6-1/16" - 1/2" = 5-9/16" Wing CG

I have the formulas setup in an Excel spreadsheet so I can plug in the numbers to get a quick answer. I also balance my planes with the battery pack on top the fuse so I can slide it around to see the variation. Sure beats the seesaw approach.

Good luck,

TGP

TerryPhillips

My Feedback: (1)

Here's a copy of my spreadsheet. Good luck.

Terry

TailTwister

My Feedback: (1)

Thanks for the sheet.

For the detail oriented, that is a killer way of looking into CG.

For me, the first CG set-up is only the beginning, and I change it from flying charachteristics.

I like the Go/No Go method for starts.

hookedonrc

Here is mine all balanced and ready to go. First flight is tomorrow. It's being fully charged as I write this. Going to try early in the morning. Forecast is for 103 in the afternoon.

dirtdr

i just put one together with a saito 91 tucked right up to the firewall. JR 537 servos in the tail, and reciever just aft of the throttle servo. I still had to put my 2700ma niMH pack right up behind the fuel tank to get the CG 6" behing the LE of the wing (without the cowl). It seems to fly great like this. have burned 1 gal of fuel thru her already... until the horizontal stab ripped off.. DOH!!
thats another post tho

hovermaster

My Feedback: (2)

i just put my 4.8 volt pack ( don't know exactly what it is but its not heavy ) just behind the throttle servo attached to that former and it balanced almost perfect. then i flew it and it was still awesome. ( i had it right behind the tank first = nose heavy )

Chris

hookedonrc

I put the battery right behind the fuel tank, and the rx right where it is pictured in the instructions. I do have a pilot in the cockpit and so he added a little weight to the tail. I added 1 oz of lead right in front of the firewall and it seems to be just right. I put 1/4 weights CA'd right on the top engine mount. Glued 3 right against the firewall and added one centered in next to the 3 other weights.

tiggerinmk

Hookedonrc,

I flew my Funtana for the first time on Sunday, mine has the stock color scheme. In the late afternoon light it sure did need some extra color on top to aid orientation.

Do you have a better picture of the top of yours? Is that band on the wing trim sheet, Ultracote/ Monokote? I'm thinking I'll need to do something similar....

As far as balance goes (since this is about balancing)..

I used the 4 JR 811 servos I got in my XP8103 promo pack plus a JR537 for the throttle, a Cermark charge switch (need to cut a large hole for this), and a JR 1100mah ni-cd. I've also got a Tru-turn on the front of my 72... The battery is mounted flat against the top of the fuse just behind the tank. Balance came out perfect for me at around 5 1/2" with no added weight.
I managed to get mine to actually balance on the GP CG machine upside down. I'm sure that if I had sneezed at it, it would have tipped over though...

hookedonrc

tiggerinva: I will check when I get home today about the top view. But basically, I bought a roll of the Blue Pearl ultracote and used it for the fuse stripes, painted the cowl stripes with Lustrekote paint. The wing stripe is between the 2nd and 3rd ribs and I just cut the stripe out of ultracote and used the Windex method for attachment. I did take a T pin and put quite a few holes in the white ultracote to make sure that bubbles were kept to a minimum.