Wiki says there are two types: Powered and un-powered. Under Powered aircraft, there are three: Propeller powered, Jet powered, and rotary powered.
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1,001 questions about the ASTB (post your scores & ask your questions here!)
- Thread starter edato
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Wiki says there are two types: Powered and un-powered. Under Powered aircraft, there are three: Propeller powered, Jet powered, and rotary powered.
fedfireman
New Member
I believe the text book answer to the helicopter tail question is something along the lines of that it houses landing gear, flight control cables, drive shafts, gear boxes, horizontal stab, and the tail rotor. Had a similar question in my EAWS and it was something like that.
For the loop question, (just for my own knowledge, not an answer) why wouldn't the most G's be exerted just before the reversal of direction? The equations given were for the bottom and top of the loop (it's probably safe to say those were given because this is something learned in flight school) but assuming there was no dive prior to the loop, would the highest G's be felt at the bottom or at the forward most point of the loop (or just before that point)? Because it would be exactly the same as a dive into a loop (like the diagrams shown in the link provided) with the exception of a negligable velocity decrease. Or am I way off track?
For the loop question, (just for my own knowledge, not an answer) why wouldn't the most G's be exerted just before the reversal of direction? The equations given were for the bottom and top of the loop (it's probably safe to say those were given because this is something learned in flight school) but assuming there was no dive prior to the loop, would the highest G's be felt at the bottom or at the forward most point of the loop (or just before that point)? Because it would be exactly the same as a dive into a loop (like the diagrams shown in the link provided) with the exception of a negligable velocity decrease. Or am I way off track?
I took the ASTB recently. I couldn't figure out the answer to the Bernoulli's Principle question because of the wording. It went something like
According to Bernoulli's Principle, as a plane flies faster:
Now I don't remember exactly what they were but it was something like
A) Lift Decreases
B) Lift stays the same
C) Lift Increases
I though it would decrease since the principle states pressure decreases as a fluid moves faster. But then again planes flying at higher altitudes have to travel faster. Higher altitude = more lift?
Does anyone have an explanation for this? Thanks.
According to Bernoulli's Principle, as a plane flies faster:
Now I don't remember exactly what they were but it was something like
A) Lift Decreases
B) Lift stays the same
C) Lift Increases
I though it would decrease since the principle states pressure decreases as a fluid moves faster. But then again planes flying at higher altitudes have to travel faster. Higher altitude = more lift?
Does anyone have an explanation for this? Thanks.
Lift increases.
Lift is directly related to velocity. The higher the velocity, the more lift you get. The lower the velocity, the less lift you get. Since it doesn't say anything about AOA, I would say the answer is C).
You are right that STATIC pressure decreases as a fluid moves faster, but that actually increases the lift above the wing. (Less static pressure on top then bottom so the wing goes up).
Also, a higher altitude would mean less lift if all else remains constant. The air there is less dense, so it produces less lift.
Lift is directly related to velocity. The higher the velocity, the more lift you get. The lower the velocity, the less lift you get. Since it doesn't say anything about AOA, I would say the answer is C).
You are right that STATIC pressure decreases as a fluid moves faster, but that actually increases the lift above the wing. (Less static pressure on top then bottom so the wing goes up).
Also, a higher altitude would mean less lift if all else remains constant. The air there is less dense, so it produces less lift.
True that according to the lift formula lift quadruples as velocity doubles. But the questions says according to Bernoulli's principle. Is the lift formula derived from Bernoulli's principle? This is the part that confused me.
Do you remember this question? It may have specifically asked lift on the upper / lower part of the wing but I don't remember exactly.
Do you remember this question? It may have specifically asked lift on the upper / lower part of the wing but I don't remember exactly.
Bernoullis principle is Total Pressure = Dynamic pressure + static pressure. For ASTB purposes, you're going to assume the total pressure stays constant.
Nothing about airplane velocity in there. Don't try to over think it. If you know that lift increases with velocity, that's the answer.
To explain lift using Bernouillis equation, just know that on a positively cambered airfoil, the air has to go around that portion faster. That means on the top of the wing you have greater dynamic pressure and lesser static pressure than you do on the bottom. It is the static pressure differential that creates lift. Since there is less static pressure on the top of the wing, the wing will rise.
The only part of the lift formula that sort of deals with Bernouilli is the Coefficient of lift (because it includes AOA)...in general though you will have a lower angle of attack for higher velocities.
I agree it is kind of a poorly worded question. It should ask about the lift equation, not Bernoulli.
Nothing about airplane velocity in there. Don't try to over think it. If you know that lift increases with velocity, that's the answer.
To explain lift using Bernouillis equation, just know that on a positively cambered airfoil, the air has to go around that portion faster. That means on the top of the wing you have greater dynamic pressure and lesser static pressure than you do on the bottom. It is the static pressure differential that creates lift. Since there is less static pressure on the top of the wing, the wing will rise.
The only part of the lift formula that sort of deals with Bernouilli is the Coefficient of lift (because it includes AOA)...in general though you will have a lower angle of attack for higher velocities.
I agree it is kind of a poorly worded question. It should ask about the lift equation, not Bernoulli.
Ok out of curiosity and just to make sure I understand this right. Is the "static pressure differential" the highest at the stall angle of attack? But this angle angle robs aircraft of speed. So overall lift is higher at high speed because velocity increases lift a lot more than AOA. does this sound right?
You're getting into some API stuff here....probably beyond what you need to know for the ASTB but yes, at your stalling angle of attack, you will have the highest static pressure differential as that is the AOA that causes the greatest coefficient of lift. Disassociate yourself from the idea though that high speeds automatically means high lift. If you have a high velocity, you will probably also have a very low coefficient of lift (because your AOA will be low). They cancel each other out if you are maintaining straight and level flight.
Dzien
Member
Just took my first shot at the ASTB today. I got a 5/7/7 45. I'm a psych major who hasn't used math or physics in over 2 years. Is this score good for anything as-is, and what should I focus on to help my math computing speed? (not aiming for any program in particular)
GPA is 3.39 (will be just above 3.4 at graduation)
GPA is 3.39 (will be just above 3.4 at graduation)
pdt1530
Member
I hate to be "that guy" but I think it's best to just look at old threads and use the search function. That's about the best response you will probably get when asking if you ASTB score is good enough. AW is a great resource! With that said, the Navy looks at the "whole person" value rather than just a single test score. Good luck!
Dzien
Member
I just saw this thread and figured it had a lot of attention and feedback. I also had concerns about older posts and their validity in today's military due to changes in scoring trends and competitiveness for different fields and admission rates for OCS.
Still learning how to use the forums most effectively at this point.
Thanks!
Still learning how to use the forums most effectively at this point.
Thanks!
pdt1530
Member
Fair enough. From what I've seen around the AW community, the best advice is to apply for what you want. Don't settle for something because you think you have a good shot, you'll end up unhappy. All you can do is apply, otherwise you already know the answer (no). So figure out what you want to do and start researching scoring trends and the backgrounds of those already in that field (i.e. using the search function). You're right in that you will get tons of feedback on this forum but I think the experienced guys will want to see that you've done your research ahead of time. Also, further feedback I've seen is that you want to put as much personal info in your profile as possible so they know who they're responding to.
Again, good luck!
Again, good luck!
iwannabeapilot
New Member
Just a quick question, I'm currently a rising sophomore at a 4-year University in NROTC. I am planning on taking the ASTB sometime next summer, before my junior year. When, during college, do midshipmen normally take the ASTB?