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Forum: Tech Log
27th Oct 2008, 22:02
Replies: 82
Views: 7,218
Posted By ft

Rainboe, yes, I was replying to you. AoA will...

Rainboe, yes, I was replying to you. AoA will typically be a few degrees negative in a vertical climb rather than zero, due to camber. Fuselage pitch relative to the airflow will be another few...
Forum: Tech Log
26th Oct 2008, 13:19
Replies: 82
Views: 7,218
Posted By ft

hawk37 nailed it, the aircraft climbed through a...

hawk37 nailed it, the aircraft climbed through a layer of gradual wind shear.

No inertial sensor worth its salt nor any external tracking as it was a line aircraft performance flight test.

The...
Forum: Tech Log
26th Oct 2008, 07:44
Replies: 82
Views: 7,218
Posted By ft

Rainboe, todays nitpicker comment: In a...

Rainboe,
todays nitpicker comment: In a vertical climb most aircraft (which have cambered wings) will in fact have a zero-lift AoA which is negative rather than zero, giving you a few additional...
Forum: Tech Log
24th Oct 2008, 18:07
Replies: 82
Views: 7,218
Posted By ft

That's where you are trying to disguise an...

That's where you are trying to disguise an assumption as a fact. On what do you base the assumption that AoA would stay the same after entering a steady climb?

AoA will, under the specified...
Forum: Tech Log
24th Oct 2008, 18:03
Replies: 82
Views: 7,218
Posted By ft

Allright, it is Friday. Time for some...

Allright, it is Friday. Time for some entertainment! I was stuck in a dull meeting and ended up scribbling a few illustrations for this thread. Here’s how most people seem to think about it at first:...
Forum: Tech Log
22nd Oct 2008, 19:25
Replies: 82
Views: 7,218
Posted By ft

ChristiaanJ, welcome to the dark side! ...

ChristiaanJ,
welcome to the dark side!

However,

L = W*cos(ca)

does hold true. You forgot to factor in D*sin(ca) in the world-vertical force balance. Have a look at balsa model's diagram in...
Forum: Tech Log
22nd Oct 2008, 17:20
Replies: 82
Views: 7,218
Posted By ft

Kristian, welcome to the discussion! ...

Kristian,
welcome to the discussion!

"T*sin (a) - D*sin (a) + L*cos (a) - W"

Almost correct. You included all the factors but forgot the condition, as specified by the requirement for a...
Forum: Tech Log
20th Oct 2008, 19:58
Replies: 82
Views: 7,218
Posted By ft

As for #2, I'll have a more analytical stab at...

As for #2, I'll have a more analytical stab at it:

In both cases, total lift generated will decrease by the same amount as a climb is initiated. L = W*cos(climb angle), no speed dependency.
...
Forum: Tech Log
20th Oct 2008, 19:33
Replies: 82
Views: 7,218
Posted By ft

a) The required net vertical force generated by...

a) The required net vertical force generated by T, D and L will still be the same as in level flight: W.

b) I don't know where you get W/W*cos(climb angle) from. It's the same thing as cos(climb...
Forum: Tech Log
19th Oct 2008, 21:13
Replies: 82
Views: 7,218
Posted By ft

"However, unless you have an all-moving wing, how...

"However, unless you have an all-moving wing, how do you change your AoA without adjusting your climb angle?"

You are confusing deck angle with climb angle. The climb angle will be 90 degrees, but...
Forum: Tech Log
18th Oct 2008, 20:51
Replies: 82
Views: 7,218
Posted By ft

Klinkenhofen, steady state effectively means...

Klinkenhofen,
steady state effectively means "no acceleration".

For an aircraft to climb in a steady state, the forces striving to accelerate the aircraft upward have to equal the forces striving...
Forum: Tech Log
18th Oct 2008, 20:47
Replies: 82
Views: 7,218
Posted By ft

krujje, sorry, no joy. :) In a steady...

krujje,
sorry, no joy. :)

In a steady state vertical climb, the lift will most definitely be zero. As you say, the lift is perpendicular to the trajectory through the air. With no opposing force,...
Forum: Tech Log
18th Oct 2008, 17:02
Replies: 82
Views: 7,218
Posted By ft

Rainboe, if that is indeed the case then your...

Rainboe,
if that is indeed the case then your accelerometer

a) does not measure the normal load factor, which is the load factor we are usually interested in in aviation

b) differs from most...
Forum: Tech Log
18th Oct 2008, 13:14
Replies: 82
Views: 7,218
Posted By ft

"So, does it mean that on takeoff acceleration...

"So, does it mean that on takeoff acceleration and landing braking deceleration, the G meter will register 1,0, because the aircraft vertical speed and acceleration are zero and the accelerations...
Forum: Tech Log
18th Oct 2008, 00:11
Replies: 82
Views: 7,218
Posted By ft

Allright, let's do the full math in your...

Allright, let's do the full math in your preferred choice of coordinate system then.

Earth-fixed steady state.

ca = climb angle

Vertical force balance gives

W + D*sin(ca) = T*sin(ca) +...
Forum: Tech Log
16th Oct 2008, 22:02
Replies: 82
Views: 7,218
Posted By ft

ChristiaanJ, I do believe you will have to show...

ChristiaanJ,
I do believe you will have to show all the diagrams and math. I note with interest how changing the coordinate system will change the weight of the aircraft. Will the local...
Forum: Tech Log
16th Oct 2008, 18:50
Replies: 82
Views: 7,218
Posted By ft

W = L*cos(climb angle) + T*sin(climb angle) -...

W = L*cos(climb angle) + T*sin(climb angle) - D*sin(climb angle)

Climbing means thrust will no longer equal drag in a steady state. Hence, part of the weight is being carried by the thrust of the...
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