I wonder if the recent air skirmish over Kashmir was a deciding factor?
Cringe but free
Nah, this one's been a few years in the pipeline. For a city-state with zero strategic depth, the capability to take off and spot threats just a few minutes earlier is a critical one. The new line of LHDs is the surprising part - no one really expected Singapore to pull a Japan with that.
Edited by eagleoftheninth on Mar 2nd 2019 at 1:42:50 AM
Echoing hymn of my fellow passerine | Art blog (under construction)
Cringe but free
The last EA-6B Prowler squadron in the USMC is finally deactivated.
Press [turn off search radar] to pay respects.
I have a question about the aviation speeds "V1" and "V2" which to my understanding are the "decision speed" at which the takeoff should not be aborted and "rotation speed" where the plane is lifted into the air.
Are there formulas to calculate these speeds and is it correct that V1 is always smaller than V2? It sounds counterintuitive.
"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled." - Richard Feynman
Yah, flying is mostly math. I want to say that V1 is determined in part by the length of the runway. If you don't have time to safely slow to a stop, you're guaranteed to run out of runway so you might as well try to get fast enough to lift off instead.
The operations manuals for lots of aircraft will typically include lots of charts to help the pilot figure out these numbers for their aircraft depending on things like the amount of fuel or payload being carried, weather conditions, wind, airspeed, etc.
V1 is the point where you are committed to take off because even at maximum braking and reverse thrust you will not stop before overrunning the runway.
"Yup. That tasted purple."
That's what it intuitively means, but I've seen a lot of references to V1 being smaller than Vr without any consideration given to runway length. So I wonder if there is some other factor involved.
Meanwhile, there has been a crash with no survivors in Ethiopia, of an Ethiopian Airlines Flight 302. If this is to be believed they had problems with the ascent speed.
Cringe but free
Heard about the Ethiopian Airlines crash - my condolences to all those who lost loved ones in it. It's pretty uncanny to have another B737 MAX 8 loss just a few months after the Lion Air accident, and at take-off, to boot. Let's hope that it's not a systematic fault in the model.
So there are several equations you'll need to balance. First off, you're likely familiar with the lift equation:
Where the lift coefficient CL is a function of the aircraft's geometry, as is the wing area A. We call the ratio of weight to lifting surface the wing loading; crafts with low wing loading naturally have an easier time gaining lift.
Roughly speaking, then, we can determine the minimum lift-off velocity vLO as:
That's not all, of course. According to FAA regulations, the aircraft isn't considered to have taken off until it's reached an altitude of 35 feet (10.7 m), at which point it should be clear of any obstacles on the runway. So we'll shelf the numbers for a while and look at the forces we need to balance for the v1.
On a ground run, the accelerating force on an aircraft is:
Where T is the engine thrust, D is the aerodynamic drag (identical to lift formula, but with its own coefficient CD and reference area), and the rest is ground friction. To decelerate the craft, you'd cut off the thrust and apply a braking force. The decision speed v1, as AFP and DBL said, is the point where you cross the threshold of being able to decelerate to zero without running out of runway length.
It's kind of late right now and I've got work tomorrow, but from there you could probably balance the plane's momentum at v1 with the decelerating forces Fbrake + D + μ(W - L), keeping in mind that the drag and lift are both functions of the current velocity.
The rotation speed v2 is different from vLO. It's the point where you've gained enough lift to start pitching your nose up in order to hit the 35 feet clearance by the end of the runway, without scraping your tail against the ground. The v2 is a function of many different variables, including ground clearance and control surface arrangement, and I couldn't find an equation for it, but since the craft is already lifting off at this point, it's higher than the v1 by default.
Unless your runway is freakishly long, that is.
Edited by eagleoftheninth on Mar 10th 2019 at 3:49:05 AM
Echoing hymn of my fellow passerine | Art blog (under construction)
rollin' on dubs
Ask the Captain: How do pilots decide when to take off?
— submitted by reader Brad, Cleveland
Answer: There are three speeds pilots use during takeoff. The first one is the decision speed at which stopping is no longer possible and the airplane is committed to fly. This is known as V1. The second speed is when the nose should be raised and the airplane is rotated into the climb attitude, known as Vr. When the airplane attains the Vr speed, the pilot who is not manipulating the controls calls "Rotate," then the flying pilot applies aft yoke or side stick to raise the nose.
Q: What are "V1" and "V2"?
A: V1 is the speed by which time the decision to continue flight if an engine fails has been made. It can be said that V1 is the "commit to fly" speed.
V2 is the speed at which the airplane will climb in the event of an engine failure. It is known as the takeoff safety speed.
Q: How do pilots determinate the V speeds and rotation moment?
— Efrain Rodriguez, Kissimmee Fla. (also submitted by Abe in India)
A: V1 is the speed by which a pilot must have decided to abort if they are going to stop on the runway. Pilots calculate this value by the runway length, obstacles, temperature, runway slope and the weight of the airplane. The airplane manufacturer provides these performance figures determined during flight testing. This flight testing also provides the proper rotation speeds for each condition. The pilot not flying announces to the pilot flying three critical speeds — V1, Rotate (Vr) and V2 (the safety speed for an engine failure).
The FAA mentions that the Max 8 is safe to use, but a lot of countries including India and Singapore (with the EU) are grounding airlines that use them until the problem is resolved.
Night Clerk of the Apacalypse.
Yikes. That is a huge fuck up.
Who watches the watchmen?
(cross-posted with the Military Thread)
Seabees and Airmen Participate in Cope North 2019 RADR Exercise
Night Clerk of the Apacalypse.
You don't get to hear a lot about the Sea Bee's these days. Interesting to see the crosslink with zoomies.
Who watches the watchmen?
Yah, not in the article, but this particular airfield repair exercise involved Sea Bees, airmen stationed on Guam, and airmen TDY from other parts of the world for a Silver Flag class that happened to align with Cope North 19.
rollin' on dubs
RE: BOEING and the KC 45
YIKES! My grandfather worked at their Renton WA plant building B-29's during WWII and he helped build may of the jets that made Boeing famous. He's turning in his grave.
I think Boeing is in it's second Dork Age - the first had a CEO who couldn't control his zipper, spying on Airbus and an government official getting sent to prison.
All night at the computer, cuz people ain't that great. I keep to myself so I won't be on The First 48
rollin' on dubs
And now some good news:
The first woman to fly commercial to space describes what it's like to see Earth from 55 miles up
The short flight qualified Moses for commercial astronaut wings from the Federal Aviation Administration. And that means she’s now the first woman to fly to space on a commercial vehicle.
It looks like the F-35 is getting an extremely capable new missile. [1]
The missile itself is an awesome weapon, and as they point out in the article it makes deep-striking stealth platforms very dangerous, especially in contested high end environments.
They should have sent a poet.
Give it a couple months and we will be getting articles about how it doesn't fit, just like the GBU-39
![[up]](https://static.tvtropes.org/pmwiki/pub/smiles/arrow_up.png "[up]"){kind=icon}
Given that the Navy has already fit this weapon on its F-35s, which have slightly smaller bays than the Air Force’s, that seems highly unlikely.
I’m afraid it might be time to face facts on the F-35 program. It’s not 2009 any more.
They should have sent a poet.
^ Yeah it's 10+ years late, still underperforming and still horrifically and unjustifiably expensive.
Given that the Air Force just sent its budget including brand new F-15X's, the writing's on the wall that the original mission and goals set out by the F-35 project are an abysmal failure.
It’s only an abysmal failure in the eyes of journalists and internet dwellers. It’s been exceeding every combat benchmark, purchases are up, and costs are finally at reasonable levels.
If you want to posit that we could have got something better for the money we spent, that’s fair. It’s very possible we could have. What we did get, though, is proving to be a highly capable platform. Which is a good thing, since we’re stuck with it.
The whole “F-15X is an F-35 killer” take is horiffically bad and I’m almost embarrassed to see it here.
Edited by archonspeaks on Mar 18th 2019 at 8:36:36 AM
They should have sent a poet.
Didn't you that supposed to be fixed last year last time the DOD report was brought up?
Its time to realize that the F-35 became a meme for a reason, and not all memes are wrong.
Edited by Imca on Mar 18th 2019 at 9:49:19 AM
Didn't see that one coming.
Who watches the watchmen?