Hello,

Quick and easy question. If a plane was too tail heavy, would the nose be pointing up and the tail down during flight? Or is it vice versa?

Im asking because I was flying my Electrify L-39 jet today and the nose wanted to point towards the sky. It was really weird.

Thanks

Depending on how tail heavy it is, it will either be very pitch sensitive, or downright unflyable and simply snap when you hit up.
If it flies nose high, but is not pitch sensitive, I would check to see if the wing or stab incidence is off.
Mark

yep nose points to the sky. did ya get it back ok?
zup

Ironically, nose heavy planes fly "nose up" as you have to pull back on the ele to keep the plane in the air. Like mrittinger said, tail-heavy planes are uncontrollable (elevator is incredibly sensitive) -- think of it like trying to push a rope.

--edfardos

Bookstar75

If you want to check out where the CG should be, try the following two CG calculators.
The first just uses the wing shape and size. The second uses the wing and tail areas.

As a percentage of MAC, (Mean Aerodynamic Center), use 25% for a fairly stable pitch, (slightly nose heavy), to 33% for a more twitchy pitch, (more tail heavy for sensitivity and snap aerobatics).

Simple CG Calculator

Full Area CG Calculator

A tail heavy plane will need down elevator to hold the tail up in flight. A trimmed out plane with the CG in the right place will usually have little or no trimmed in up or down elevator.

I say another flight characteristic of tail heavy planes is very short flights too. And with abnormal endings too. :>)

There is an old expression that "A nose heavy plane flies badly, a tail heavy plane flies once."

Jack

Originally Posted by Bookstar75

Hello,

Quick and easy question. If a plane was too tail heavy, would the nose be pointing up and the tail down during flight? Or is it vice versa?

Im asking because I was flying my Electrify L-39 jet today and the nose wanted to point towards the sky. It was really weird.

Thanks

No, Like others have said, nose heavy will result in slightly higher pitch at X speed due to the downward force on the tail. Otherwise flying nose high at X speed is a symptom of flying too heavy or flying too slow.

Originally Posted by Bookstar75

Hello,

Quick and easy question. If a plane was too tail heavy, would the nose be pointing up and the tail down during flight? Or is it vice versa?

Im asking because I was flying my Electrify L-39 jet today and the nose wanted to point towards the sky. It was really weird.

Thanks

Just to satisfy my curiosity: was this the first flight of your airplane? Did you scratch build it? If it was a kit, did the mfgr. supply a CG point? How much power were you carrying when your aircraft demonstrated the nose-high characteristic, or, what speed were you at as a rough percentage of total at this time?

I have a homebuilt that is nose heavy when I am flying solo, and the only thing I notice is the elevator requires more stick force to increase positive pitch, and in the pattern at approach speed it requires more up trim to reduce force needed for flare, or in other words the stick force for the approach and flare is higher. I would assume an RC airplane would possibly run out of elevator on landing trying to keep the nose high since the airspeed controls the effectiveness of the elevator. Anybody care to comment?

I have also flown an RC plane at a significant tail heavy condition......once. LOL

In my experience, the kit maker's recommended cg is a starting point and cg must often be adjusted due to slight tail heaviness, wing, or stab incidence or motor down thrust variations. Biplanes and some high wingers tend to pitch up after lift off probably due to a pendulum affect. I like a new model to be slightly nose heavy for the maiden and trim flights as insurance against against serious rolling to the left and stall-crash syndrome after lift-off. Nose heaviness is easier to diagnose and handle during first flights and usually can be adjusted by moving battery pack rearward or adding small stick-on weights to the underside of the stab.

THere's a couple ways I check the CG in flight.

1. Power off, 45 degree dive. Let go of sticks. what does it do?
Dives worse= tail heavy (holding dwon trim to keep tail up)
Stays course= just about right
Climbs= nose heavy(holding up trim to keep nose up)

2. Flip it upside down either half-loop or half-roll
How much Down Stick does it take? (depending on airfoil, wing placement, etc)
A TON= Nose heavy
A little ( 1/4 stick or so) Just about right
It climbs= You have big problems, way tail heavy!

Severe tail heavy, think of a Marlin jumping out of the water trying to throw a hook.
I just went though a slight tail heavy maiden, nerve racking 'til you get it down safely.

if you fall down do you fall to the sky or to the ground......

Originally Posted by edmoor

if you fall down do you fall to the sky or to the ground......

Relevant to the trimming, not relevant to the flight attitude.

Originally Posted by bartricky

Severe tail heavy, think of a Marlin jumping out of the water trying to throw a hook.
I just went though a slight tail heavy maiden, nerve racking 'til you get it down safely.

aka... The 'Sabre-dance' landing.

as in "Ye Ha Cowboy."


rc

Heretofore known as Butt Pucker Syndrome.

mw