GPutt33

My Feedback: (2)

I thought I would post this separate from my kit building post so I could make sure I got an answer. I have done a prelim CG check of the plane in the bones, and found that it seems to me to be quite tail heavy I knew this would be something to deal with due to some of the bashing I did.

I target shoot, and found that 10 - 158 grain bullets would balance it out perfectly.

If my math is correct this is .2257 pounds or 3.611 ounces. Is this to much weight to add to this plane with the Saito 91??

GPutt33

My Feedback: (2)

Here is what 10 - 158 grain semi wadcutters look like

I am hoping the CG doesn't change much more after I have the MonoKote on it.

If I can, I will try to epoxy these on the front side of firewall right under the engine on either side of the crank vent hole.

So, what do you all think

coyote

My Feedback: (21)

Try placing your Rx battery and Rx as far forward as possible. If this isn't enough, 3-4 oz of 158 gr SWCs should be no problem on the Four Star. Might make a suggestion though - instead of epoxying, place them in a small heavy duty zip lock freezer bag, rubber band and wrap in foam then place under tank. Out of sight and you can add or remove as necessary. Airplane should be RTF with an empty tank prior to adding any extra weight. My 4*60 / TT Pro-61 took about a dozen SWC's in the nose to balance. Enjoy your Four Star. Bob

Jetmech-inactive

If you havn't already, move battery pack as far forward as possible. I had to put almost 4OZ. in the nose of my GP Spacewalker with a Saito 91. Don't worry about the weight;
you'll have MORE than enough power with the Saito up front!
You could also go with a larger Receiver battery pac for some extra weight forward thats beneficial.
I'll probably need even more weight than yours since I'am only putting a OS61FX in mine.

LarryC

If you use 405 gr 45-70 bullets it won't take as many!!

Larry

Dago Red

My Feedback: (11)

looks good-----keep up the good work---

LarryC

I have an OS 91 four stroke on mine with an APC prop. I was able to balance it with placement of the battery. I at first had a 70 on it and it needed some extra lead. I'm not sure how much your engine will weigh, but it will probably come in pretty close. Don't worry about it if you need an ounce or so, but it would be best if you put it where it can be changed, like coyote suggested.

Good luck with the Four Star. I think you'll like it.

Larry

TerrellFlyer

AFTER THE PLANE IS FINISHED RECHECK THE C/G,EVEN A HALF POUND THE PLANE WILL FLY,JUST NOT AS NIMBLE AS A LITER PLANE.

GPutt33

My Feedback: (2)

Well it seems a few of you out there do reload also (nice to know )

Just so you know, I have the 1100Ma Batt in it and it is stuffed as far forward under the tank as I could get it. I have the receiver right behind that with about 2 inches of foam separating the two.

Coyote - good point on not making them a permanent part of the plane with epoxy. Just in case I do need to change CG later.

LarryC - Point taken, these just happened to be handy. I've got some 240g JHP that would be my largest, but the new Cabella's in Dundee is just up the road about 65 miles , so next time I'm up I'll look in their bulk department and pick up something that will take the count down from 10

Happy Thanksgiving All

ebeygin

you said your battery is under the tank? why not try putting it in the same compartment as the servos??... the plans have the battery under the tank.. but they do mention the fact that you should place them in the compartment to the right.. if CG problem is an issue...

-eugn

GeeBeer

I have the same exact plane. On the nose I have a Tower .75 (I LOVE this engine BTW... runs TERRIFIC!). No spinner, I use chicken stick. Battery is mounted under the fuel tank up in the nose. I had to add exactly 3oz to the nose to make plane balance in middle of spar where I like it on this plane.

JetAwithPrist

Not sure how far along you are but,

Have you considered a weight loss program for the tail? It doesnt take much wieght way at the back to affect the cg. So, if you cut a couple more lightening holes in strategic places or, as silly as it may sound, sand the tail some more, i think youll find you have to add a lot less weight. What about a lighter tailwheel? A couple lightening holes in the elevators and rudder?

just my .02

rcpilot-ajaxrc

I am just getting back to my 4*60 after almost 2 years. It is framed, but not covered. I can't find my plans anymore and don't know where the CG is. Can someone tell me. Thanks.

Dago Red

My Feedback: (11)

its usually 25%-28% of the cord of the planes wing, thats what most planes use, unless it is a delta, or swept wing.

Crash_N_Burn

I just finished a 4*60 and had the same problem, even with a Jett .76.

So I doubled-up on the batteries and installed two switches for a parallel system.

No additional ballast. Extra fly time. Security.

I'm familiar with your weights...I'm a .45 paper-puncher and re-loader but never thought of using them for ballast.

Thanks for the tip!

hookedonrc

I have a 4*60 with an OS91 Surpass on it, and yes mine was real tail heavy. Probably because I added Super Mario as the pilot. However, be careful of one thing, I put the weights on with epoxy in the front part of the engine well. (on the bottom &sides) The weight was enought to cause the fuselage cheeks to vibrate enough to begin separating the checks from the bottom right where the bottom curves up and meets the sides. I re-glued it, and then ran a dowel across the front of the cheeks, and screwed a 1/2 in. hex head screw in each end. That worked great. (Included the pilot pic...just cause I like it.)

Gene Chernosky

My Feedback: (182)

I've built two 4*40's and both had the airframe lightened somewhat with additional/larger lightening holes and taper cut control surfaces. CA is quick and epoxy is strong, but both are heavy...too much of them in the tail can add up quickly. I like to use Super Phatic, a thin aliphatic resin glue that gets into all of the spots thin CA does...but it dries (loses weight) instead of simply setting...and it is stronger than CA or epoxy. Also, DON'T make the mistake to follow the instructions to the letter as to where to put radio gear...I don't do this on ANY plane! Leave yourself as wide of a window (fore-aft) for placement of the radio gear as you can. Once the plane is in the final stages of assembly, then, by checking the CG as you go, place the radio gear so as to not need a lot, or any weight. A lighter plane ALWAYS flies better!

Wh00ps

Mine came out just a bit tail-heavy. I used a 14oz tank, and did some modification to the tank floor to get it to fit, so the battery couldn't go under the tank. Had an 1100mAh pack right behind the former at the back of the tank, receiver right behind that, and if I remember correctly, I mounted the servo tray somewhere near the mid-point of the fuselage opening. GMS .76 on the nose. I initially added 1.5 oz. of stick-on weights to the engine compartment, and it flew great. After a while, they started to un-stick and fall off, so I just let them. Eventually had no added weight, and it still flew awesome. Better, even. Right up till that fateful day.... *sigh* :cry:

wfortney99

My Feedback: (310)

Hi Gene,

The Super Phatic glue sounds much better than the Elmers and Titebound alphatic I've been using. Where do you get the Super Phatic glue ?


Bill

Gene Chernosky

My Feedback: (182)

Go to...

http://www.hobby-lobby.com/index.htm

then go to their product list, then glues.

...there you go