has anybody played with the cg to determine the optimum take off performance.... thinking fully forward cg may require more elevator to rotate and speed to lift vs a more rearward cg
does a more rearward cg requiring more forward elevator to accelerate cause more drag than optimum?
has any body tested this or have experience?
Climb is usually more important than raw TO distance where I fly. I keep CG aft and get 1200 FPM with the Scout at SL on the Coast of OR (8.5 6 6 Tires, ABI TW).
(1000 FPM GW )
Last edited by 8GCBC; 12-18-2012 at 11:33 AM. Reason: Added 1000 FPM GW, ABI TW
-- 8GCBC: 2100A, 31136.R, 8.566, C3000A
A&P, ATP, SES, CFII, MEI
Fly with me here: http://www.youtube.com/watch?v=SXI48e1heuo
Testing, testing, testing.Originally Posted by swoeric
I ain't saying nuthin'
I'll reply with my technique just to keep things going because I think it is an excellent question. I keep a fairly aft CG but not for takeoff reasons. I make every landing in the Cub a short field landing and get on my brakes from the moment I touch down. These are wheel landings and I get aggressive on the brakes. To be aggressive with brakes means you need to have a rearward CG.
I like full forward trim for landings because I like the feel of needing to tug back on the stick to be stabilized. This helps 'stick' the plane to the ground making a wheel landing too.
On takeoff I keep that full forward trim where it was for landing. This helps the tail pop up quickly. So I keep a more or less neutral stick position, a little bit forward most of the time, until the tail comes up on its own. With two notches of flaps the airplane will fly at this point.
It seems to me that not forcing the tail up too quickly with elevator yields less drag and a slightly quicker take off.
Flying with skis helps define where that sweet spot is for the stick position easier than wheels. A little too much or too little stick on skis can mean a noticably longer take off run. But it is easy to find the sweet spot and once defined the sight picture stays the same.
"They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety." Benjamin Franklin
Yes it has been tested. And I would say there is no pat answer. The same aircraft in different configurations ( build-ups, mods) likes different answers. You find the coarse answer then fine tune from there. Every one is different. You have to find which works best for your airplane. Right Dave? Jerry B.
A Pa11 is soloable from both seats. You learn real quick that if you get yourself in a pickle that you will be off and climbing faster if you get in the back seat.
Glenn
And the back seat is more comfortable too
It also depends on the kind of surface you're taking off from. If it's solid and smooth, than aft CG should give you the best performance. But if soft, you don't want the TW to drag along through it, so a fwd CG will help get the tail up earlier. In my -12, an aft CG on landing allows me to fly slower and still have some tail authority to arrest a sink. The tail usually gives up before the wing does.And the back seat is more comfortable too
In the 11, on soft sand takeoffs, I just blew the tail up with throttle and down elevator so that the tail never touched. On landing, I used the tailwheel as a brake. I much preferred the back seat.
Dear Shooter,
does this mean you will have to have two classes for the short field contest New Holstein?
Class A: Front seat.
Class B: Back seat
Last edited by Cajun Joe; 03-10-2013 at 02:46 PM. Reason: added contest so as not to confuse George
Are you supporting "back seat pilot's"?
Best not tell my sweetie!
I don't know where you've been me lad, but I see you won first Prize!
Spinner 2: In reply to your post of 12-18-12, I have used your technique of "full forward trim" for both landings and take offs for several years, but I could never explain why I do that as eloquently as you did. I knew it just worked best for me as I am one who flies strictly by feel and never look at the instruments when landing or taking off. I have even been scolded by other pilots for using forward trim for landing, so I was glad that someone else uses this technique and could properly explain why! I, however, always start take offs with no flaps and pull full flaps when I feel the plane is ready to fly. I feel this helps the plane accelerate quicker without any drag from flaps, and then I pull full flaps to break loose from terra firma. This, however, may not work as well with lower horsepower planes. Thanks for your explanation!
Ed Doyle
Who is Ed Doyle?
I think I forgot!
Just a farmer from Kansas. Really
Farmer from Kansas you say. Does he have a dog named Toto and some red magic slippers too!!
Steve
They were only red in the movie.
They were silver in the book.
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