center of gravity
 

hi all - i flew my hangar9 aspire 3 times and crashed 3 times
it seems to climb and stall like its tail heavy
the center of gravity supposed to be between 3 and 3 3/4 from the leading edge of the wing
when i put it in the CG stand at those measurements - it tips backwards
when i put weight in the nose it balances nice and sits level on the stand
is this the way its supposed to be balanced for flight ?
it seems to be very front end heavy now when i hold it ...... Regards Garry~

RE: center of gravity
 

Yes, it should be level with an empty tank at the recommended CG before you fly it for the first time. THEN you can make fine adjustments later to suit your tastes.

RE: center of gravity
 

ok..... thanks for the info - i will give it a try on the weekend ... Regards Garry ~

RE: center of gravity
 

remember you can fly a plane that is slightly nose heavy but tail heavy is almost impossible. set your cg with an empty fuel tank. try and move weight to get cg instead of just adding weight.
good luck

RE: center of gravity
 

Garry,

Start with the CG at the 3 3/4 inches back mark. Balance the airplane there with the fuel tank empty. Achieve balance by moving your battery forward or aft until the plane is balanced. Move the batter as it is the heaviest and easiest to move. Don't add weight.
Once the plane is fueled up it will be nose heavy and will move toward balanced CG as fuel is burned off. Once you have flown the airplane and get it trimmed out you can move the CG forward toward the 3 inch mark to see if the flight characteristics improve. Remember, "A nose heavy airplane flies poorly, a tail heavy airplane flies once".
Good luck.

Regards,
doubledee

RE: center of gravity
 

Awsom - thankyou - - will try another flight tomorrow - plane sits nice on the cg stand now:D

RE: center of gravity
 

doubledee has the right idea, but he has it backward. Start closer to the 3" mark at first, and then move it back toward the 3 3/4" mark if you want more performance.

Personally, I would start it right between the two.

RE: center of gravity
 

Just to clarify something I see a lot of confusion about. The CG is the point on the airplane where it sits level when supported.

Airplane kits/arfs have a "recommended CG" specified somewhere, in the plans, instructions or whatever.

In other words, the instuctions don't tell you where the CG is, they tell you where the CG SHOULD BE. You measure where it IS, then move things or add weight to move it to where it should be.

So, when you put the plane on the balancer the first time, you never really saw where the CG was, since the plane fell tail-down. You did find out that the CG was behind the recommeded location, ie the plane was tail heavy.

Now that you've moved the CG to be within the recommended range, I'm sure the plane will fly better. Good Luck and have fun!

RE: center of gravity
 

Well i gutted the inside of the plane and started again so i could reposition the battery and use its weight as a slide to get my CG correct - the battery now sits where the esc and receiver once were and vise versa
i didnt touch the servos - just had to solder longer wires from the motor to the esc and make a new battery tray and relocate the on-off switch to the other side of the fuselage - all is good now except the weather ..........Regards Garry ~:D

RE: center of gravity
 

I have only seen a true tailheavy plane fly one time a few years ago. This was a good pilot and what a ride he had trying to get that thing back on the ground without damage.

RE: center of gravity
 

I see a lot of people talking about a fuel tank... This plane is an electric powered glider. So ballance this plane fully loaded, ie. with the battery installed. Placing the CG to the forward limit will give a faster glider with less glide time without thermal activity. Ballancing toward the aft limit will decrease your glide slope and and slow the plane down giving you longer flights. As a newbee I recomend the forward CG mark for you untill you become more comfortable with the plane. As you move the CG aft you will find the plane will be more sensitive (responsive) to control inputs and it will stall more quickly. Good luck. Have fun. Never give up.

RE: center of gravity
 

I stand corrected. Minnflyer is right.
Senior moment. :eek:

Regards,
doubledee

RE: center of gravity
 

Don't feel bad DD, I have more of those than I care to think about! :D

RE: center of gravity
 

Well thanks to you guys my plane is ready to fly
i posted some pics in my profile gallery THANKYOU once again Regards Garry

RE: center of gravity
 

Is your plane electric? If so...

I have an Aspire EP and had the exact same problem. First three flights resulted in my first three crashes. In all cases, it stalled and fell to the left.

I then checked the center of gravity only to find out it was way to far aft. To get the center of gravity to the correct spot (2-1/2 to 2-3/4 behind the front wing edge) I had to move the battery so far forward that it was not longer in the battery bay, but fully forward of the battery bay and above the ESC. I filled the battery bay with foam and rubber banded the battery in the forward bay.

Today, I took the airplane out for a fly and it flew beautifully, nothing to it... Hanger9 really messed up the RTF version of this plane. It's really a good flyer, but only after it is setup correctly.

Best of luck!

Kurt

RE: center of gravity
 

my old girl is about to get a heart transplant

i also came across this helpful site - half way down theres some pics (asp) of his aspire with the new improved setup

regards Garry ~ http://home.flash.net/~jecramer/aspire.htm