Shifting CG forward

[Dan Thomas]

Wow, thanks for all the responses. Super helpful. I won't address all of them, just those that kind of stuck out. The plane was weighted a year ago. Not calculated W&B but actual weighted W&B - unless the bugs on the leading edge had too many burgers, I would say the W&B should still be pretty accurate today.

Now, that leaves one question: Did the guys that did the reweigh level the airplane as per the service manual? Here's what it demands:



When it's levelled on the scales, the nose oleo will be pretty much flat and sometimes you have to let air out of the nose tire or add shims under the mains. It looks weird, believe me. The idea is to get it into normal cruise attitude. It this isn't done and the airplane is sitting in normal ground attitude, the actual CG is shifted back closer to the mains and the calculations will show the airplane to be tail-heavy. High-wing airplanes are especially critical in this regard. So much weight up high that moves back in normal ground attitude.

Other mistakes include leaving stuff in the airplane, or leaving the doors open. It all matters.

 

[David Megginson]

I upgraded to the 150 from what we call "advanced ultralights" in Canada so it does feel like a big plane to me, at least for a year or two - at which point I'll probably have to upgrade again, in small steps to always get that "big plane" feeling

Welcome to the Canadian contingent on PoA. Was your former AULA a Challenger? I love watching those land on the ice in the winter.

 

[Magman]

To second Dan’s comments.

ACCURATELY determining stations while in the level weighing is not to

be taken for granted.

When weight is applied to the wheels they may move forward or aft.

Obvious on Mooney’s, Ercoupes , and oleo struts.

Sagging spring gear can change with age as well.

 

[Boundary Waters]

I learn something new every day on this forum.

Since my wife doesn't operate the plane, she has lots of leg room on her side and as long as I can somehow secure the baggage from sliding forward towards the rudder pedals...

Tricycles have rudder pedals?

 

[Dan Thomas]

I learn something new every day on this forum.



Tricycles have rudder pedals?

Yup. You need them to steer the airplane while taxiing, and they're a handy place to put the brakes, too.

 

[farmrjohn]

Yup. You need them to steer the airplane while taxiing, and they're a handy place to put the brakes, too.

Well except for the Ercoupes. Rudder pedals? We don't need no stinking rudder pedals.

 

[Boundary Waters]

"Brakes, what are those?" said the Luscombe pilot.

 

[Dan Thomas]

"Brakes, what are those?" said the Luscombe pilot, just before she ran off the end of the runway.

FTFY

 

[Magman]

If you W & B is really correct and you want to keep the 150 for a while here is

a possibility.

Your aircraft is already approved for a rather heavy weight forward of the Firewall.

The Battery; which is on the right side of the Firewall.

Perhaps making a “ mirror image” of the existing BatteryBox and structure

on the Left side of the Firewall would give you the location you desire.

A Field Approval could be a possibility using this technique.

I used the “ mirror image” to install Landing & Taxi Lights in the Right Wing

Of a 172.

Total 4 in all.

 

[Boundary Waters]

"Brakes, what are those?" said the Luscombe pilot.

A more complete version...

The Luscombe pilot kept her wings flat and pulled power back as she started her approach using gravity to her advantage. Her airspeed stable, she arrived just in front of the "X" with almost zero excess energy. Keeping her wing flat, she added power in the flare, which dissipated all of her kenetic energy, making her ground roll incredibly short.

Her passenger looked at her and said, "No brakes?"

"Brakes, what are those?" said the Luscombe pilot.

 

[MauleSkinner]

The plane was weighted a year ago. Not calculated W&B but actual weighted W&B - unless the bugs on the leading edge had too many burgers, I would say the W&B should still be pretty accurate today.

As others indicated, even weighing can come up with bad numbers. As a quick “reasonableness” check, did the CG move more than a tenth or two of an inch?

 

[wayne]

Not as long as my first true cross country: 1200 miles in a 65HP Aeronca Chief

How much more do you have to go?

 

[Jack Cabano]

As others indicated, even weighing can come up with bad numbers. As a quick “reasonableness” check, did the CG move more than a tenth or two of an inch?

(This thread prompted me to join PoA. So send all complaints to Chisgoesflying. )

The 150J I regularly fly has a EW of 985 lb. At a theoretical GW of 1600 lb with 310 lb in the seats, 120 lb in "A," and nearly full LR tanks it has a CG just forward of the aft limit. Moving 40 lb out of "A" into "B" would put it just aft of the rear limit.

G, H, J, and K models are the same. Others might be I don't know. Maybe this helps as a comparison.

 

[Dan Thomas]

A more complete version...

The Luscombe pilot kept her wings flat and pulled power back as she started her approach using gravity to her advantage. Her airspeed stable, she arrived just in front of the "X" with almost zero excess energy. Keeping her wing flat, she added power in the flare, which dissipated all of her kenetic energy, making her ground roll incredibly short.

Her passenger looked at her and said, "No brakes?"

"Brakes, what are those?" said the Luscombe pilot.

Good to see that someone has been getting good training. It's too rare. But don't get too reliant on that engine stopping your descent. Someday it will cough and you'll have nothing to flare with.

 

[David Megginson]

A more complete version...

The Luscombe pilot kept her wings flat and pulled power back as she started her approach using gravity to her advantage. Her airspeed stable, she arrived just in front of the "X" with almost zero excess energy. Keeping her wing flat, she added power in the flare, which dissipated all of her kenetic energy, making her ground roll incredibly short.

Her passenger looked at her and said, "No brakes?"

"Brakes, what are those?" said the Luscombe pilot.

I don't understand why she added power in the flare: that's just more energy that she had to dissipate. Unless the Luscombe is stunningly different from every other single-engine piston plane, you can get rid of the forward energy simply by using it to arrest your descent.

 

[Boundary Waters]

I don't understand why she added power in the flare: that's just more energy that she had to dissipate. Unless the Luscombe is stunningly different from every other single-engine piston plane, you can get rid of the forward energy simply by using it to arrest your descent.

My Luscombe isn't too different-- in terms of flight characteristics-- from the Talorcraft I learned to fly in. From what I hear it's very similar to Aeroncas, Hi-wing Pipers and 120/140 Cessnas. But it isn't a Helio-- with its huge slats-- that I can mush in at 20 mph, nor is it a Fokker 7 that I can hang on its prop.

With my wings level and my airplane in flight attitude (not nose down) I simply decrease my thrust to decrease my lift to allow gravity to return me to earth. At flare I need to dissipate this vertical energy so that I will kiss the ground rather than smack it. A short burst of power-- and I had the engine running providing some forward thrust during my whole decent so this burst is not a "shock" to the system-- just as I feed in elevator at flare (the timing is what you really have to practice) increases my forward energy enough to trade a small amount of horizontal distance for a decrease in velocity downward. My flare decreases my lift and adds drag limiting how much I move forward-- relative to my initial slope-- before touchdown, and gets me into proper attitude and position for landing.

Ground effect gives me a small cushion but I am touching down at a low forward airspeed with very little stored energy-- either vertical or horizontal. So, unless I am on a very short runway, brakes are superfluous. On touch-and-goes, instead of a burst of energy followed by pulling the throttle back to idle, I smoothly open it while remaining in ground effect until I have enough airspeed to climb. On soft or rough fields it's a touch-and-go until I decide that I like the turf / dirt / mud.