Fly Lah!

refusetakeoff wrote:thanks for the answers...
i rephrase back my question....
why we need 2 dieffrent ground for DC and AC?why cannot at the same ground?

from the wire/power system we can easily determine it AC or DC....thnaks for the clue...

my bad...wrongly expressed the question....

AC and DC ground Interesting and good question!! Let me solve the myth.
All circuit, no matter how simple it is, there must be a significant resistance for DC and impedance for AC. Until here, i think some of our electrical friends can break the pot.
Let's resume this, aircraft's AC used 400Hz, therefore a significant magnitude of impedance due to the reactance from the component in the circuit. These reactance often found as the "noise residue" in the AC ground. Therefore, when high frequency AC circuit is proximately near the DC circuit, the reactance may transfer into the DC circuit. The manufacturers want a clean and distinctive ground for avionics, that would be easier to diagnose when AC and DC are independent system, rite?

visegrip wrote:hi guys !!! i hv a question here.... why on some acft both eng can start at the same time , while for some acft the eng can only be started one at a time

First, let's us forget about what aircraft can do your so called "1-shot" start. And we look how to start an engine.
To start an engine, normally you power up the APU first so that the APU can provide the bleed. The bleed will be used to crank the air starter in the engine. When the engine rotated, fuel injected, you are ready to ignite the engine. For airbus, when you start the engine, the system will temporarily to stop the bleed to aircon pack, and direct all the bleed into the air starter.
Now, back to your question, if you want to start both engine, please tell me how much psi of bleed your APU must be designed to generate?

khye89 wrote:hai....erm....why aircraft horizontal stabilizer is the anti aerofoil shape?i mean convex under stabilizer surface..

Hi there, I will try to answer your question @@
If I'm not mistaken, you are talking about the "typical" wing arrangement (sry i forgot the correct term) of which the foreplane produces most of the total aircraft lift. With this type of configuration the centre of presure is behind the centre of gravity, causing the aircraft to have a nose down turning moment. So in order to counteract that nose-down moment, a down-load is created by the anti-aerofoil shape of the horizontal stabiliser. About the basics of aerofoil i think you should know then, for horizontal stabiliser its force generated will be downwards.
Hope it helps, and correct me if I went wrong somewhere.

StevenPeong wrote:
Hi there, I will try to answer your question @@
If I'm not mistaken, you are talking about the "typical" wing arrangement (sry i forgot the correct term) of which the foreplane produces most of the total aircraft lift. With this type of configuration the centre of presure is behind the centre of gravity, causing the aircraft to have a nose down turning moment. So in order to counteract that nose-down moment, a down-load is created by the anti-aerofoil shape of the horizontal stabiliser. About the basics of aerofoil i think you should know then, for horizontal stabiliser its force generated will be downwards.
Hope it helps, and correct me if I went wrong somewhere.

thanks pro...i get the same answer tat u given...anyway....if a interviewer ask,wht is torque loading?wht should we answer?

how do we determine oil canning?
and what type of repair we need to do?

"How?" I don't get you. I hope you do know what 'oil canning' is.
Repair as per SRM.

visegrip wrote:how do we determine oil canning?
and what type of repair we need to do?

Another quick question,,

StevenPeong wrote:
Hi there, I will try to answer your question @@
If I'm not mistaken, you are talking about the "typical" wing arrangement (sry i forgot the correct term) of which the foreplane produces most of the total aircraft lift. With this type of configuration the centre of presure is behind the centre of gravity, causing the aircraft to have a nose down turning moment. So in order to counteract that nose-down moment, a down-load is created by the anti-aerofoil shape of the horizontal stabiliser. About the basics of aerofoil i think you should know then, for horizontal stabiliser its force generated will be downwards.
Hope it helps, and correct me if I went wrong somewhere.

There are still incomplete infos on your explanation ...never mind it is a learning process.

1. design of C of G of an a/c is common to be 'placed' forward of C of P (like you mentioned), but that doesn't determine whether or not an a/c is tail-heavy / nose heavy. get it? that's why the THS (trimmable horizontal stabilizer) trim range can counter the tail and nose heavy condition.

2. for an a/c with a sweep back wing design, normally they are tail heavy when fueled to full. when fly @ fuel consumed, the c of g gradually moving forward . some a/c incorporated with stab-fuel tank(tail plane) for purpose of countering nose heavy condition during flight.

3. remember the c of g principal, it also has limitation---> c of g envelope or range. don't exceed it or you'll be in trouble.

btw i don't understand about anti-airfoil shape stabilizer?? or i have missed some part?

as far as i understand, anti-airfoil design means it is against an aerodynamic design. like a box shape bus?

what i know the THS is designed to be symmetrical on both it's top and lower camber.

NO he got it right.
The curve surface is at the lower section of the THS while the upper surface is almost flat.
The lift is now on the lower surface and with the C of P point acting like a fulcrum, the 'opposite' lift of the THS will keep the nose up and also making pitch changes easily achieved with little/less effort.

torx wrote:NO he got it right.
The curve surface is at the lower section of the THS while the upper surface is almost flat.
The lift is now on the lower surface and with the C of P point acting like a fulcrum, the 'opposite' lift of the THS will keep the nose up and also making pitch changes easily achieved with little/less effort.

OK i got it.. thank you. it is true that all a/c incorporated with THS will have this kind of design (almost flat on top)? or only some of them?

Most aircrafts that I have worked with, yes.

hi there..

i got one question that i want to be asking here...FYI,i got the bridging junior technician for MAS and i will joining them on this 2nd august..so i want to ask, what will they conduct for the bridging junior technician class?is it for familiarization class?