W&B Versus Speed

[KLRDMD]

We all know that airplanes are faster with a more rearward CG. There is less elevator trim necessary for level flight.

I was surprised at the difference in my 231. I fly +/- 10,000 ft in cruise on just about every flight. Rarely do I cruise below 9,500 ft and I don't go above 12,500 ft very often either.  The vast majority of my flights are solo, occasionally with one other person and with 2-3 others a few times a year. So my day in and day out flight regimen is to take off with full fuel, solo and climb to +/- 10,000 ft for cruise. I fly LOP at 59% power. That very consistently gives me 160 KTAS on 9.0 GPH. I see it on every flight.

Today I flew from Tucson to LA, climbed to 10,500 ft to cruise, solo, departed with full fuel. The usual. It was hot, over 100ºF on the ground and still 22ºC at 10,500 ft. I twist the true airspeed dial just for fun on most cross countries; it gives me something to do. I consistently see about 133 KIAS (the OAT is generally lower than today) which generally means 160 KTAS.

Today I saw 137 KIAS which based on the temperature was about 167 KTAS. It seems I picked up about 7 kts today. I had a fairly heavy backpack, medium sized piece of hard sided luggage and my B-Kool fully loaded with two large blocks of ice. The rearward CG must have given me an extra 7 kts. I expected 2-3 kts but 7kts ??

[gsengle]

Hell, I slide my pilot seat all the way back in cruise. Bet is worth a knot.


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[carusoam]

A photo out the back window can give you an idea of the elevator deflection under different conditions...

Make sure your WnB is in line with your expectations. Don't want to accidently fall out the back of the envelope...

Best regards,

-a-

[aviatoreb]

3 hours ago, gsengle said:

Hell, I slide my pilot seat all the way back in cruise. Bet is worth a knot.


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Better to put the plane into autopilot then climb way back into the luggage compartment to enjoy a nice nap and also a few extra knots.

[gsxrpilot]

29 minutes ago, aviatoreb said:

Better to put the plane into autopilot then climb way back into the luggage compartment to enjoy a nice nap and also a few extra knots.

Just be sure to set an alarm so you don't forget to switch tanks and REALLY start picking up some extra knots. 

[Guest]

For the ultimate in aft C of G you could have one of Marauder's ladies ride in the back.

Clarence

[buddy]

Yep, just slide your seat all the way back and that will give you a couple of knots.

[DanM20C]

There was a 5kt difference between the forward and aft limit in my C

[mooneyspeed]

Thats a pretty warm OAT, well above ISA.  That alone will give you an increase in TAS for the same % power setting.

 

[steingar]

The W&B of my M20c basically says not to put the big guys in back.

[Rustler]

The late Russel Stallings once told me that when they used to race Mooneys in his earlier days (those of you who knew Russel know that in later times he couldn't get into a Mooney), they would take off with two people in the front seats, and as soon as they were underway, the guy in the right seat was sent to the baggage compartment. I've had a vision of this transfer in my mind for many years.

[mooneyspeed]

An aft and in limits C of G should give you a higher TAS because the horizontal stab is producing less induced drag to counteract a forward C of G.

 

 

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[kmyfm20s]

Your density altitude was giving you more benifit from the turbo than usual. 10.5  isn't the most beneficial altitude for a turbo but with today's rediculous heat your plane thought it was flying higher. Plus with the thermals you where probably getting some help.  I took off for imperial valley airport today a 4pm and it was 115 on the ground. At -50 msl airport the DA was 4400'. Today was one day I would have appreciate a turbo:)

[KLRDMD]

Just now, kmyfm20s said:

Your density altitude was giving you more benifit from the turbo than usual. 10.5  isn't the most beneficial altitude for a turbo but with today's rediculous heat your plane thought it was flying higher. I took off for imperial valley airport today a 4pm and it was 115 on the ground. At -50 msl airport the DA was 4400'. Today was one day I would have appreciate a turbo:)

East to west, headwind. 10,500 was the best altitude.  Today I departed KVNY a bit before 3PM, it was 37ºC on the ground. I climbed to 11,500 ft where it was down to 17ºC and landed at Tucson (KAVQ) 2.5 hours later where it was 43ºC on the ground. It was continuous moderate+ turbulence. And there were weather deviations. The joys of flying in the afternoons in AZ in July. True airspeed and fuel flow were quite nice !