CG for a tiger 60
 

I'm tring to balance this plane. The manual says the CG is 3 3/4 to 4 3/4 inches back form the leading edge. I marked the wing at 3 3/4 and tried there:eek: not even close. I 've read a lot of comments about these planes being tail heavy and mine is no different. I have the battery and receiver as far forward as possible. I added some weight to the front of the plane , just some lead I had laying around. After two pieces about the size of a acorn I got it to balance at about 4 1/2 inches. I'd rather it balance at 3 3/4 or 4 for the first couple flights to see how it handles. Any Ideas on what to do. I was thinking about cutting a hatch under the gas tank and putting the battery there, that would put it foward about 3 1/2, 4 inches. Do you think this would be worth doing or should I just add the weight?

RE: CG for a tiger 60
 

Be careful, and check 2x, but go ahead and add weight until it weighs in at the front cg point. The worst that can happen is it will land a little hot with the cg too far forward. As you get the cg toward the rear, it will get sensitive to the elevator. Only you can tell what is just right for you, and that will change a little as you get familiar with it. With the cg too far to the rear, it won't land for you at all. I use the ability to roll axially as an indicator that the cg is good. Also, when you are inverted, how much down elevator you need to maintain level flight is another indicator. If the cg is nearly spot on, you should need very little.

RE: CG for a tiger 60
 

I balanced mine in the middle of the recommended range. I added a fair amount of weight to the compartment under the tank. My Tiger 60 weighs in at a tad over 9 lbs. Heavy but flies awesome with a TH .75. It will even outleg my brothers 4*60 with a GMS .76 and 7lbs.:D:D

RE: CG for a tiger 60
 

There is room under the fuel tank for a four cell flat pack however this was still not enough for mine. I had to still add 3/4 oz to the nose to get it center of the recommended CG. After some time on the plane I took all of the weight off of the nose 1/4 oz at a time. I really like the way it flies with the CG futher back than center. I am not sure exactly where it is but I like it where it is at.

RE: CG for a tiger 60
 

I've managed to get two A123 cells in series under the fuel tank on mine. With an OS .75 AX on the front, and a custom built cowl, it came out balanced about the center of the range without adding any more weight.

Great looking Tiger you have there Sourkraut!


Tom

RE: CG for a tiger 60
 

I added some weight to the plane last night and it took almost 2 1/2 ounces to the nose to get it to balance at center. Is that a lot to add? I have'nt weighed the plane its self yet but will as soon as I can.

RE: CG for a tiger 60
 

Somebody said they come out tail heavy? Really?

Mine flew ok out of the box. I think I opened the box around July '07. I balanced it about a half inch aft of where the main gear are held in the wing. That was about where the book says to place the CG. Like I said, it flew ok, but really didn't want to knife edge or snap roll. I never bothered to run the measurement through geistware.com because the Tiger has been around a LONG time and I figured they'd have the CG pegged pretty good.

Well, the other day I ran the numbers and found out how conservative the new manufacturer is with the CG. Don't worry a bit about any CG that's not more than about 4.75" back. Middle of the winter, I moved the battery pack to the rear of the equipment bay, under the wing hold down bolts basically. It snapped a bit better and didn't lose altitude as much in KE. I still didn't bother to run the numbers yet. For fun one spring night I doubled the elevator chord. It snapped better, but of course didn't KE any better. Well, like I said, I ran the numbers the other day. And decided that I hadn't paid the little girl sufficient attention. I picked out a piece of lead that weighed .8oz and glued the sucker inside the fuselage just ahead of the rudder hinge line. Whoo hah........ Nice. Still didn't bother to check the CG because you really don't need to if you're working with known flight performance. I had already cut the elevator throw on low rates to tune the new larger elevator, so had not a worry in the world about the dreaded TAIL HEAVY DANGER.

After seeing how nicely almost an ounce of lead did for the flight performance, I stuck another .8oz back there. She flies excellently well now. Decently quick snap rolls, but not too quick. And KE is solid. The CG is about 4.75" back now.

You got to remember that the Tigers have big tails. Yeah, sort of sounds like a joke, but they do have pretty decently large horizontal area back there, and "back there" is decently far back. So you get a lot of pitch stability from those largish tail feathers.

Do not worry a bit about rebalancing a model with known flight characteristics. That is, if you have reliable info like geistware.com supplies, and you don't go crazy with the weight. And you do need to be careful and accurate checking the CG if that's the way you're going about it. I've got some years doing this and knew that an ounce would be very safe to test with MY Tiger60. And wound up with 1.6oz back there and an airplane that is now flying excellently. And safely.

If you either move a CG back on a model you've flown already OR choose to start with the aft most recommended CG location when building one, keep in mind that the elevator will be effective. Expect for the airplane to respond to elevator and you'll be ok. Set the elevator throws with a conservative low rate throw and you'll be more than ok. But do pay attention to check CG location accurately and with some decent numbers. No balancing "with a little nose down tilt" is going to cut it. Balance level and you know right where it is. Being accurate is how you do a CG "safely".

RE: CG for a tiger 60
 

da rock, my plane was kit built and just about every post I've read people say their tiger came out tail heavy. Well I add about 2 1/2 ounces. I'm going to fly it to see how it does and then add or pull weight as needed. thanks for all your help. James

RE: CG for a tiger 60
 

Yes, too little description often blows and otherwise good sentence. Nowadays, with most of the Tiger60s that show up at the field being ARFs, saying, "Tiger60s are naturally tail heavy" isn't going to be true most of the time. I think there is one kit Tiger flying at the 3 fields I fly at. And last time out at my favorite, we had 4 Tiger60 ARFs and one TigerII ARF.

Sorry I didn't pick up on yours being kit built. Gotta pay better attention.

Don't worry about 2 1/2 ounces in a 60size model. But also don't worry too much about flying it at 4 1/2. The airplane is a very stable flyer. And won't get freaky with the CG anywhere in the mfg's range. They're one of the best weekend warriors available today. I just spent an hour last evening cleaning mine up from a months worth of hard use. I've actually worn the tread down on the wheels somewhat! And I fly off grass!

BTW, does the kit Tiger60 have lightening holes in the aft part of the fuselage? The ARF uses liteply for the fuse with most of it removed as lightening holes. An excellent use of liteply, btw. I was figuring to build a kit if/when I kill this one.