There seems to be a myth about the A-10 Thunderbolt II aircraft.
Apparently, the general consensus is that it slows down due to its 30mm gatling gun firing.
But it seems to me that even a gun of that power could not slow an object so big and heavy, and that the slowdown is an optical illusion.
I seem to recall someone doing the math on the CBC once, but I can’t find a trace of that anywhere.
Can anyone do the math or point me to something that can dispel this horrid myth?
Source: http://members.aol.com/Stravonski/private/gun.html#Gun Design
Link recommended by http://www.fas.org/man/dod-101/sys/ac/equip/gau-8.htm
According to this page the gatling gun bullet contains 300g of depleted uranium. At 3900 rounds per minute, and assuming 850 m/s muzzle velocity, the impulse from the gatling gun is:
(300g) * (850 m/s) / (1/65 sec) = 1.6x10[sup]4[/sup]N = 3700 pounds
That’s almost half the maximum thrust of one engine. (The A-10 has two.) And that’s not even including the force from the explsive gas escaping from the muzzle. I can easily believe that the plane slows down visibly when firing the gun.
Upon preview I see Duckster has posted the official number and I’m not sure why I’m off by a factor of 2. Maybe the 300 DU is only part of the bullet?
I was all prepared to say that it’s no myth, but a quick search proves otherwise
Welcome to the Boards!
Hmm, good call Tuckerfan. I guess each “burst” is so short that speed drop is not significant - a 70 round burst would only be a 1-second burst.
I was speaking with an engineer who worked on these guns and he said they are limited to how long they can fire as the barrels heat up rapidly. The 3900 rounds/min is theoretical; he said even if the gun could be supplied with a constant source of ammo for that long, the barrel would be flopping about like a piece of cooked spaghetti.
So short bursts it must be. I never thought about the “reverse thrust” involved, but in short bursts it’s probably neglegible.
Depleted uranium is a terrible weapon that, like landmines, will end up killing more non-combatants in the long run…
Capn
Is that a fact or an opinion?
Why? It’s just a hard, heavy bullet, right? It’s depleted of radiation, after all.
DU is simply another heavy metal. It has interesting effects when used as it is, and being considerably denser than lead, a similar-sized projectile (limited by the bore diameter) will retain energy longer (meaning a flatter, longer trajectory) and being harder than lead it does better at defeating armor.
When it impacts a target, the Ke of the projectile essentially vaporizes the DU in a pyrophoric effect I’m not entirely up on.
This makes a fine mist, a vapor, of DU, which, being a few orders of magnitude heavier than air, settles rapidly. However, people breathing the dust or vapors can run into the toxic effects, just as they can when exposed to other heavy metals like lead, cadmium and mercury.
Having remnants of DU on the battlefield is not much more dangerous than the lead dusts from conventional bullets, and by FAR less dangerous than unexploded munitions or land mines.
Uranium found in nature is mostly U-238, with a small amount of U-235 mixed in. U-235 is used as nuclear fuel, and depleted uranium is the leftover U-238 after you removed the U-235. However, even though U-238 is unsuitable for nuclear reactors and bombs, it’s still a radioactive substance.
U-238 is an alpha emitter. Alpha particles carry a lot of momentum, but can easily be stopped, e.g. by a piece of paper or human skin. So it’s pretty safe to handle if it’s contained and sealed. However if it is ingested or inhaled, it can be deadly. There’s little danger to Air Force personnel handling the DU bullets, but once the bullets are used for their intended purpose, some of it may turn into fine powder and cause health problems for people living near the target.
I totally love the A-10, it’s ugly but it’s a cool kind of ugly and it can take an insane amount of punishment for an airplane.
If paper or skin is sufficient to stop the alpha particles there should be no issue with DU shells. The DU shell is encased in aluminum so I’d imagine it’s perfectly safe to handle and only a problem after it’s been fired and vaporized on a target.
The A-10 is one of those rare military projects that is effective, relatively cheap, does it job, the field personnel love it and scares the hell out of the enemy.
So of course, the Air Force wants to get rid of it. No kidding! There was an op-ed piece in the NY Times about it a couple of weeks ago. Seems the Air Force doesn’t relish the dirty job of supporting ground troops with slow, low flying aircraft. Not sexy enough for them. They want the Army to provide their own support with helicopters.
This is back again? IIRC the A-10 was slated to be scrapped prior to Desert Storm but the A-10 acquitted itself so well it got a new lease on life. I thought one of its charms was its slow and low flying ability allowing it to loiter longer than other jets over the battlefield.
If there was a replacement that was better (or being considered) I could see getting rid of the A-10 but to my knowledge there is no replacement and helicopters don’t fit the same bill. Helicopters can be devastating to tanks but I would think they are slower than the A-10, less survivable and more limited in the number of tanks one can take out without re-arming compared to the A-10. Further, the pilot in an A-10 sits in an armored bathtub (essentially) that makes his survival much more likely than a helicopter pilot and I would assume an A-10 has a better shot at dodging missiles than a helicopter does. I know the A-10 is able to soak-up a good deal of damage and still return to base safely. I’ve seen pictures of A-10s shot-up that made it back and I can’t imagine a helicopter being able to do the same thing with an equivalent amount of damage.
Did the NT Times article mention any legitimate reasons for scrapping the A-10 or is it really all just a sexiness issue?
Whack,
I’m not pretending to be an expert but from what I know, all of your information is essentially correct. The article was written by Robert Coram. Don’t want to cause copyright problems but I don’t think I can link to NY Times archives. Here’s a few excerts:
Quote:
In early April, Maj. Gen. David Deptula of the Air Combat Command ordered a subordinate to draft a memo justifying the decommissioning of the A-10 fleet. The remaining eight active duty A-10 squadrons (in 1991, the number was 18) could be mothballed as early as 2004.
The decision to take this aircraft out of service is the result of entrenched political and cultural shortsightedness.
The A-10 was also the most storied aircraft of the first gulf war. It flew so many sorties the Air Force lost count. The glamorous F-117 Stealth fighter got the headlines, but Iraqi prisoners interrogated after the war said the aircraft they feared most were the A-10 and the ancient B-52 bomber.
To understand why the corporate Air Force so deeply loathes the A-10, one must go back to 1947, when the Air Force broke away from the Army and became an independent branch. “Strategic bombing,” which calls for deep bombing raids against enemy factories and transportation systems, was the foundation of the new service branch.
. . . In fact, the A-10 never would have been built had not the Air Force believed the Army was trying to steal its close air support role — and thus millions of dollars from its budget — by building the Cheyenne helicopter. The Air Force had to build something cheaper than the Cheyenne. And because the Air Force detested the idea of a designated close air support aircraft, generals steered clear of the project, and designers, free from meddling senior officers, created the ultimate ground-support airplane.
. . .because of the philosophical aversion to the close air support mission. Couple that with the Air Force’s love affair with the high technology F/A-22 ($252 million per plane) and the F-35 fighter jets (early cost estimates are around $40 million each), and something’s got to give.
Despite budget problems, the Air Force has decided to save money by getting rid of the cheap plane and keeping the expensive ones.
The Air Force is promoting the F-35 on the idea that it can provide close air support, a statement that most pilots find hilarious. But the F-35’s price tag means the Air Force will not jeopardize the aircraft by sending it low where an enemy with an AK-47 can bring it down. (Yes, the aircraft will be that vulnerable.)
If the Air Force succeeds in killing the A-10, it will leave a serious gap in America’s war-fighting abilities. By itself, air power can’t bring about victory.
Unquote.
That old oxymoron “military intelligence” rears its ugly head.
If you take a good look at the plane (brought to my attention by a former a-10 crewman), the wings are not parallel to the axis of the fusilage. They are tilted up somewhat, so that when the wings are flying at 0 degrees AOA (Angle of Attack), in level flight, the front of the plane points DOWN! Aids in visibility, and in aiming.
In addition, this design also maintains proper configuration for landing, as the wing has a fairly large AOA at slow speeds, which raises the front of the plane some, allowing proper “rear wheel first” 2 point landings.
-Butler
pleasepleaseplease please give those rejected Air Force planes to the Marine Corps. pleasepleaseplease please
That’s what I say! (Or let the Army have back their own air support.)
Let the Air Force do what they’re good at which is flying fast, spending money on fancy new toys and playing video games.
This is going to constitute a hijack, rant and IMHO post but I can’t help it and offer my apologies up front.
What the #@%! are our military planners thinking!? How can they possibly be left to get away with scrapping the A-10…or even just trying to?
Let’s see…we have an aircraft that is unique and has NO replacement. We have an aircraft whose development costs have presumably already been absorbed. We have an aircraft that is far cheaper (relatively speaking) than anything else that might even try doing the same job. We have an aircraft that saves American soldiers lives (both the pilot and the people on the ground are safer…again relatively speaking since being in a battlezone can never be called ‘safe’). We have a plane whose operational costs are far cheaper than the alternatives*. We have an aircraft that has proved it effectiveness in battle (IIRC they were responsible for taking out 900+ tanks in Desert Storm…more than any other single weapons platform).
I understand politics creeps into many things and the military is in no way immune to it. However, how politics can overcome a clearly winning design for which there is no replacement is wrong. Hell…I’d say it’s downright criminal! The taxpayers lose but infinitely more importantly the soldiers lose as well. While you could probably never definitvely place numbers on this I’d wager more soldiers/pilots will die with the absence of the A-10.
If the airforce doesn’t want the A-10 because they see their role as something other than close air support then fine but those A-10 squadrons certainly should be given to the arm of the military that does see that as its role.
[sub]*I was watching a show recently on The History Channel (Tales of the Gun I think) that was talking about the F-4 Phantom and its initial lack of a gun/cannon. Eventually it was thought this was an oversight and they equipped a few Phantoms with gun pods and sent them out into Korea (Vietnam?) to give them a try against Russian MiGs. The pilots were told to be honest about their effectiveness. The report came back something like this (all from memory so I’m sure it’s not spot on but the essence is here). “We engaged and shot down three MiGs. One was shot down with a missile and the other two with cannon fire. The missile kill cost the US givernment $46,000. The first cannon kill cost the US government $1,183 and the second cannon kill cost the US government $982.” The whole point of this little tale is that an A-10 is FAR more cost effective at hunting tanks than anything else. The A-10 can use missiles as a helicopter can but I’d wager one missile costs more than the entire load of cannon ammo on board. Further, the cannon is probably good for taking out more tanks than missiles. Dump your load of eight missiles (or whatever) and you have to go back to base if you’re a helicopter…the A-10 can keep pounding away with its cannon.[/sub]