CG Musings

[Brian Scranton]

I flew with some family yesterday. Max gross. Hot. High. So I thought it would be fun to mess around with forward and aft CG positions. I normally fly with a pretty forward CG (me+wife) and a kid in the back, full fuel, so I was interested in what a max rear CG would feel like. 

Flight #1, I had 300lbs in the front seats, 420 in the rear and 40 gal of fuel. 

Flight #2, I had 400 in the front seats, 220 in the rear, and 40 gal of fuel.

I gotta tell ya, the takeoffs both felt the same. Off the ground at 70mph, began an immediate climb to vy. Never felt tail heavy. The only difference I noticed was on landing. I had burned ~8gals...and on final, at 80mph, my sink rate was a little high and I had to add a good amount of power to make it to the runway. So, the moral for me was that are beloved Mooneys fly really well with varying CGs! 

I've also read that a more aft CG results in a faster airspeed. I did not notice this, but I think it's a hard thing to measure. I do, on all flights once in cruise, move my seat back and watch GS. I never really see anything happen. 

 

[jaylw314]

2 hours ago, Brian Scranton said:

I've also read that a more aft CG results in a faster airspeed. I did not notice this, but I think it's a hard thing to measure. I do, on all flights once in cruise, move my seat back and watch GS. I never really see anything happen. 

The theory is with more aft CG, the horizontal stabilizers need to produce less downforce at any given speed to maintain level attitude.  I'm not sure what proportion of the wing lift this is, so I'm not sure what amount of speed change to expect.

[gsengle]

I gain at least a knot of groundspeed in cruise solo by sliding my seat all the way back...


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[DanM20C]

In my C the aft limit gave me nearly 5kt faster cruise than when I was solo with a forward CG. 

Moving my seat back was about 1kt too.

[N9201A]

I gain at least a knot of groundspeed in cruise solo by sliding my seat all the way back...


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+1. Works every time. Physics. I believe.


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[LANCECASPER]

1 hour ago, gsengle said:

I gain at least a knot of groundspeed in cruise solo by sliding my seat all the way back...


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In that case Maurader could gain 5 knots if he put one of his girls in the backseat. 

[gsengle]

In that case Maurader could gain 5 knots if he put one of his girls in the backseat. 

[RLCarter]

5 minutes ago, LANCECASPER said:

In that case Maurader could gain 5 knots if he put one of his girls in the backseat. 

More like 20kts from what I've seen

[Brian Scranton]

I should have taken a photo of the horizontal stabilizer...dang.