kswarbird

Would anyone know the CG and throws for this plane? would appreciate any help.......thanks, Pat

pilott28

My Feedback: (27)

I had one of the early SM F18C's. I have sold it and don't have the throws, but the CG was 48 inches back from the tip of the nose. My plane weighed just shy of 30 pounds. The Weight and Balance sheet is on the JPO Website ... www.jetpilots.org go to members and select weight and balance from the submenu.

I do recall that the CG was quite a bit behind the point indicated in the instructions, which was supposed to be on the wing spar. I ended up about an inch or more behind that front spar.

BCoston

My Feedback: (7)

Ailerons 12-18mm
Elevator 40-45mm
flaps 20-25 for take off and 60mm for landing

CG for me is 22mm behind front spar, until I moved it back to there I had a bad nose tuck in tight turns. Now it is a ball to fly.

ravill

My Feedback: (11)

I've had a ton of success with the CG on the spar. I had bad luck when I moved the CG back. But that's just me!

Raf

pilott28

My Feedback: (27)

This was exactly my experience. Hard to stabilize on the approach, too. I almost gave up on the plane after a few flights until I moved the CG back.

blackcat

careful measuring from the spar, mine (now busted up) and my friend georges have 25mm (1 inch) difference in spar location, my spar is 100mm from the leading edge ( where it meets the fuse) and the cg ended up 25mm behind that, georges is 125mm on the spar. skymaster recommended on the spar for mine which was way too far forward. check your measurements from the leading edge.
hey ravill, how far from the l/e is your c/g, out of curiosity?

BCoston

My Feedback: (7)

It depends on what version F-18 you have as to where the cg location is. I was about to sell mine until I read an old thread that Keith posted and moved my cg back 22mm from the spar. It is a fun to fly now. Read this thread for more info.

http://www.rcuniverse.com/forum/m_5351184/tm.htm

Craig B.

Listen to Blackcat and the other guys regarding their c of g measurements. They are right on with the c of g being 22-25mm behind the front spar with blackcat's version of the kit. She flies beautifully with the c of g at that point......see takeoff and landing attitudes in photos. The main thing with this model is getting a positive AOA for takeoff and getting the c of g right. You are then 90% there. Mine rotates with minimal elevator input but never balloons on landing unless I screw up badly! In the air she really grooves nicely.

ravill

My Feedback: (11)

This brings up a good point. KSwarbird, do you have the new version (carbon tubes, bearings on the elevators, etc...) or the old one (aluminum spars, brass bushings on the elevators,.....)??

The old SM F-18C's with the aluminum spars flew great with the CG on the Spars. This is where I placed the CG on all of the other F-18C's I've had. (1 "old" SM F-18C, 1 "new" F-18c, 1 X-treme Jets F-18C, 2 Jet Legend F-18C's) The flares on landing get a little harder when the CG is pulled back.

I love these little hornets as I think they are great flyers! And great lookers as well!

Ask Duke from HI, when they were testing the F-18C with different CG's, he noted that some would tip stall right out of the sky with an too AFT CG. This is true for any airplane, jet, prop, control line, free fly, etc... But remember the F-18C (or E or F, or A...) have leading edge extensions, with the super hornet having even more of a leading edge extension.

I can measure this when I get home. I have a buddy who so scared to fly his hornet that he asks me where my CG is like every week. I keep telling him, its at the same place it was last week. That airplane is alittle above his head...

Raf

kswarbird

thanks for all the good info........Pat

Craig B.

Hi Raf,

Mine is the old version with the aluminium spars and brass bushings as was blackcats. We found they flew best with the c of g 22-25mm behind the front spar. Never any sign of a tendency to stall, flare excessively or balloon on landing. Rotation is easy on takeoff with none of this tendency to leap off the ground. And all of that is with the front tank draining to rear tanks and landing with rear tanks mostly full. I have hauled mine pretty hard around turns while flying and have never noted any signs of impending stall.

They are an awesome airframe. I share your enthusiasm for the hornet!

Craig.

Mylo

I've almost finished my Skymaster F-18C and I'm currently balancing the aircraft.

My Skymaster F-18C also has the aluminum spar and brass bushings, but as Blackcat already pointed out, the location of my forward spar is 25mm (1 inch) aft of his. We placed the two wing halves side by side to compare, and I was surprised to see the difference. Unfortunately, we haven't compared the physical dimensions of the two fuselages to see whether the location of the root chord moved as well.

I purchased my SM F-18C about 12 months before blackcat; the other noticeable differences are that the fuselage formers of my aircraft are held with carbon rovings, the flap servos were to be fitted in the fuselage (I put them in the wing) and that my centre tank was significantly smaller.

Assuming the location of the wing relative to the fuselage is the same; then balancing my aircraft on the front spar is equivalent to what you and blackcat already determined as the most suitable location.

It's taken a long time to finish and I'm really looking forward to getting the Hornet in the air.

George

Craig B.

Hi George,

Sounds like you are on the right track and Sparksey and Mr Bennett know what they are doing. Good luck with the 18 and let us know how you go. She looks great in the air!

Craig.

BCoston

My Feedback: (7)

My F-18C has carbon fiber tubes and the new elevator servo mechanism. It wanted to nose tuck real bad with the cg on the spar. I started moving it back until I reached 22mm and now it is very stable in a turn and enjoyable to fly. My only problem is maintaing a good visual reference because I have a hard time seeing the Blue Angles scheme that I have.

ravill

My Feedback: (11)

To each their own! Some folks fly a little nose heavy(I'm in this camp, I'm a wimp) and some like to fly a little tail heavy!

As long as we're having fun, that's what counts.

Raf

Craig B.

Fair call Raf. Whatever works!

Craig.