Aces High Bulletin Board
General Forums => The O' Club => Topic started by: MwXX on May 08, 2005, 11:55:15 AM
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http://www.web-solutions.at/videos/1108759352.wmv
http://www.web-solutions.at/videos/1108759352.wmv
:aok
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thanks for sharing the vid. :)
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Great vid. I was surprised at the high cyclic rate of the guns as they aren't gattlings.
IMO that and the T38 are a couple of the best looking planes made.
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Beautiful planes. I so wish the F-20 Tigershark would have been produced.
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Originally posted by Maverick
Great vid. I was surprised at the high cyclic rate of the guns as they aren't gattlings.
IMO that and the T38 are a couple of the best looking planes made.
What you hear is about 4,000 rpm from it's two 20mm revolving breech cannon. Actually in those short burts these guns are faster firing than gatlings - which need a second to spin up to full cyclic rate.
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Originally posted by GRUNHERZ
What you hear is about 4,000 rpm from it's two 20mm revolving breech cannon. Actually in those short burts these guns are faster firing than gatlings - which need a second to spin up to full cyclic rate.
Thats not entirely true...
First, the M61A1 Vulcan cannon can fire up to 6000 rpm.
Second, the Vulcan cannon is powered by the aircrafts hydraulic system. From a *stopped* position to barrels rotating at full speed happens so fast you cant see the acceleration happening. (I've seen this with my own eyes)
I worked on an F-4E in 1982 that had problems firing its gun on multiple sorties. The barrels would rotate but the rounds werent firing. After multiple tests on the ground we finally put the aircraft on jacks, started the #2 engine, disconneted the firing lead from the gun, then depressed the trigger and checked for voltage at the firing lead. (All this was done to simulate the aircraft being airborne).
It's been so long since this happened that I forget what the problem ended up being. However, I was so impressed at how fast the gun accelerated to full speed that I can vividly recall that portion of what we did to this day. One second the barrels were sitting still, as soon as the trigger was pulled they were nothing but a blur.
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is F-5 the U.S. equivalent of the MiG-21?
btw those cannon fires sounds like fart! :D
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Yes the Vulcan has a higher top cyclicrate, but it is not instant like you think. Our percetion of time and what our eyes see is much different than the perception of time of something that fires 100 rounds a second. The gatling takes some time to spool up and it does result in lower ROF compared to revolver cannons on thge first trigger pull.
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Originally posted by 1K3
is F-5 the U.S. equivalent of the MiG-21?
I think the F-5 was more of a low-cost and barebones fighter, at least on western standards. It was built for export to less developed "friendly" countries, hence the nick name "Freedom Fighter".
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The gatling takes some time to spool up
From my experience that time is very negligible. In fact it's so negligible that it cant be seen with the naked eye. If the human eye can see the difference between 30 fps and 60 fps I have to believe it can see *spool up time* in one second.
When I worked F-15A/B's at Elmendorf AFB in Alaska many many times during combat turnarounds we were allowed to use the aircraft hydraulic system (while the #2 engine was still running) to upload ammunition to the gun system. The gun system never started off slow, rotation speed just happened as soon as you pulled the lever to rotate the system.
I would have to see some data that verifies that TWO single barreled cannons initially fire faster than ONE 6 barreled cannon in order to believe that. ;) Especially when you consider the cyclic rof for the TWO cannons is 2000 rpm LESS than the gatling.
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Originally posted by mora
I think the F-5 was more of a low-cost and barebones fighter, at least on western standards. It was built for export to less developed "friendly" countries.
we still use them accross the US as aggressors. They do great in that role of teaching ACM.
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So far I havent been able to find anything concerning spool up time with the gatling guns and how that affects the rof. I did find that the M39 cannons rof was 1500 rpm. Two of the M39 cannons combined rof is 3000 rpm, HALF that of the M61A1 Vulcan.
Imo there would have to be some serious spool up time on the Vulcan cannon to make a pair of M39 cannons faster firing than one Vulcan. Off to give Google another workout ;)
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Its a factor elfie, tell me can you see tyhe difference between 70 rounds per second and 100 rounds per second with your own eye?
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Originally posted by GRUNHERZ
Its a factor elfie, tell me can you see tyhe difference between 70 rounds per second and 100 rounds per second with your own eye?
when you have less than a thousand rounds does it really matter the diff. between 100 and 70 RPS?
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Originally posted by GRUNHERZ
Its a factor elfie, tell me can you see tyhe difference between 70 rounds per second and 100 rounds per second with your own eye?
So post a link :)
As far as your question goes, I have no idea, never tryed it ;)
The difference would have to be greater than the difference between 70 rounds and 100 rounds in order for the M39 cannon to fire faster than the M61A1. In fact it would have to be at least 51 rounds since a pair of M39's has half the rof (combined) of the M61.
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Originally posted by Gunslinger
when you have less than a thousand rounds does it really matter the diff. between 100 and 70 RPS?
Yes it does in todays high speed jet combat. The more rounds you can put on target in as little time as possible can mean the difference between a kill and being killed.
According to an F-15 pilot I spoke with while we both sat on alert duty, USAF pilots are taught to fire 100 round bursts. (Eaglr can verify this if USAF pilots are still taught this) During our lengthy conversation he never once mentioned spool up time on the gun being a factor. I would think that USAF wouldnt keep using the gatling guns if the revolving breech guns were faster.
*edit* Just thought of something. The revolving breech mechanism should have a spool up time as well.
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Ahh but thats the kicker Elfie. JSF was supposed to get Mauser BK27 revolver but had to settle for GAU12 gatling when the license production deal couldnt be worked out.
Reading up on that plane some time ago is where I got this information about initial rof advantages of revolvers. And just like you said, the important thing is rate of fire in the shortest instant from trigger pull and here revolvers are better.
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Found this on the Mauser BK 27.
http://www.global-defence.com/2000/pages/mauser.html
This reference talks about a revolutionary new feed system for the Mauser BK 27, a linkless system to feed the round to the gun and then to return the spent casings to the ammunition drum. I dont see what is so revolutionary about that, the M61A1 has used that same system for decades now.
This reference does list: Time to rate: instantaneous for the Mauser.
Found it! :D
http://www.answers.com/topic/m61-vulcan
Some experts feel that despite its high rate of fire, the Gatling-type weapon is hampered by the time it takes for the weapon to spin up to its maximum rotation speed (about 0.5 second). As a result, a one-second burst only fires about 70-75 rounds, which some experts feel is not enough of an advantage over revolver cannon like the ADEN/DEFA 30 mm weapons to justify the additional weight and complexity.
The F-5's twin M39 cannon with a combined rof of 3000rpm would put out 50 rounds per second. The Mauser Bk 27's rof of 1700 rpm would still be slower than the 70 - 75 rps of the M61A1.
The article I linked to has this to say about the 20mm gatling gun in use by the USAF today.
Despite its reliability and tremendous rate of fire, the Vulcan has been increasingly criticized in recent years for its limited performance.
The ballistic characteristics of the 20 mm round are relatively poor, with the projectile losing energy quickly, and its killing power and accuracy are marginal compared to the heavier 25-30 mm rounds favored by European and Russian air forces. Efforts to develop a higher-caliber replacement for the M61 have thus far had limited success. The USAF spent a great deal of money in 1970s on the 25 mm GAU-7 cannon for the F-15, using caseless ammunition, but it proved to be a failure and was abandoned in favor of the Vulcan. The five-barrel GAU-12 Equalizer 25 mm gun used in the AV-8B Harrier II is a Vulcan derivative, but despite greater hitting power (since it fires a heavier round at virtually the same muzzle velocity) it has yet to find wide application.
While the M61A1 does have a spool up time (didnt know that prior to this thread, thanks Grun!), it still appears to have a faster rof even for one second bursts than the revolver cannons do. Problems with the M61A1 appear to be more about the ballistics of the rounds themselves as oppossed to an actual rof.
Now I am wondering how the Mauser Bk 27 achieves an instantaneous rof since the revolving breach mechanism obviously has mass that needs to get in motion. Maybe it's the fact that it has less mass than the gatling gun?
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OK you two, go get a room! :p
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Originally posted by Maverick
OK you two, go get a room! :p
LOL, sizing eachother up....
Anyways, awesome video and awesome post, MwXX!
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Originally posted by Elfie
While the M61A1 does have a spool up time (didnt know that prior to this thread, thanks Grun!), it still appears to have a faster rof even for one second bursts than the revolver cannons do. Problems with the M61A1 appear to be more about the ballistics of the rounds themselves as oppossed to an actual rof.
one thing I do know about the 61 from talking to crew chiefs, they have a HELL OF ALOT of torque! So much so that iproperly installed/fired weapons actually end up tweaking the Air Frame itself pretty bad.
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I haven't seen the aircraft version, but the shipborne Mauser
revolver cannon is pretty impressive. Of course I only saw it on
one of those Story of the Gun specials on the Mauser company.
:)
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Originally posted by Gunslinger
one thing I do know about the 61 from talking to crew chiefs, they have a HELL OF ALOT of torque! So much so that iproperly installed/fired weapons actually end up tweaking the Air Frame itself pretty bad.
Elfie could probably give you a better discription of this, but
one of the bigger problems with the Vulcan was that the
enormous amount of gases expelled by the gun were screwing
up the engines on the earlier fighters using them.
In fact, if you check the early F-4es against the later blocks
you can see how they changed the shape of the shroud to
assist venting of the gases downward and away from the
intakes.
Early F-4E (http://www.kitreview.com/ reviews/f4ereviewdw_1.htm) Late F-4E (http://www.geocities.com/cap17.geo/1973small.jpg)
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0/\/\G!111 MiG28s!!!1111
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Originally posted by mora
I think the F-5 was more of a low-cost and barebones fighter, at least on western standards. It was built for export to less developed "friendly" countries, hence the nick name "Freedom Fighter".
I think F-5 (in the 1960s-70s) is the best MiG killer the USAF did not use (back then, USAF said there's no need. "We'll pound em with missiles @ BVR range on our heavy pound for ground fighters)
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Originally posted by Rino
Elfie could probably give you a better discription of this, but
one of the bigger problems with the Vulcan was that the
enormous amount of gases expelled by the gun were screwing
up the engines on the earlier fighters using them.
In fact, if you check the early F-4es against the later blocks
you can see how they changed the shape of the shroud to
assist venting of the gases downward and away from the
intakes.
Early F-4E (http://www.kitreview.com/ reviews/f4ereviewdw_1.htm) Late F-4E (http://www.geocities.com/cap17.geo/1973small.jpg)
Rino, iirc thats the reason the F-15 and F-16 have their M61A1's mounted in the wing root.
Ever see a pic of a aircraft equipped with the M61A1 after it has fired the cannon? The huge quanities of gas that come out leave residue on the plane that has to be cleaned off daily by those poor slobs the weapons mechanics. :D
Gunslinger, I can believe that about the torque produced. The M61A1 has a Blast Diffuser/Muzzle clamp attached to it. Some sort of muzzle clamp is required to keep centrifugal forces from *spreading* the gun barrels during firing. If you had ever actually held one of those gun barrels and felt its weight you would find it incredible that they could bend enough to make any difference....but they can and do.
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M61 works great on the Navy CIWS..too bad the rest of the system is crap.
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Originally posted by ASTAC
M61 works great on the Navy CIWS..too bad the rest of the system is crap.
Out of all the gun jams I saw, not one was atrributed to a malfunction in the gun itself. All but one were attributed to something in either the feed system or the ammunition drum failed. The one jam not attributable to one of the above was caused by a round cooking off in the conveyor assyembly AFTER it had left the gun. That was the worst jam I ever saw. We had to disassemble the conveyor and ammo drum to remove the ammunition and spent casings. That was the only time I ever heard of a gun system being taken to the shop for maintenance while it still held live ammunition. Cost 100 grand to fix the entire system.
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how can a photo plane strafe?
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Yep that was it, it seems i didnt remeber all the deatils correctly but thats the argument some pose in favor of revolvers.
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didnt the internally mounted m61 in the ptotype starfighter bring it down ?
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Originally posted by IK3
I think F-5 (in the 1960s-70s) is the best MiG killer the USAF did not use (back then, USAF said there's no need. "We'll pound em with missiles @ BVR range on our heavy pound for ground fighters)
Are we talking talking about the F-5A "Freedom Fighter" or the F-5E "Tiger II"? AFAIK the latter has much better performance and the "A" didn't even carry a radar.
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Thats correct Mora. The A model was optimized for the air to ground role. The E model was optimized for air superiority.
http://www.fas.org/man/dod-101/sys/ac/f-5.htm
Pretty good read on the F-5.
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Originally posted by 1K3
is F-5 the U.S. equivalent of the MiG-21?
btw those cannon fires sounds like fart! :D
The F-5's characteristics are very similar to the MiG-21. Thats why it was chosen to be the Aggressor aircraft for the USN and USAF.
I've never seen an M-61A1 fire irl, but I have seen them fired on video tapes, they sound like a buzz saw. :D
Rino your links arent working for me, but I suspect that I never worked on an F-4E that didnt have the modified shroud. The early F-4E's were most likely modified as well.
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A nice plane seen them as a kid alot here.
http://home.att.net/~jbaugher1/f5_22.html
http://www.cavok-aviation-photos.net/Twenthe.html
(http://www.geocities.com/cornfield12000/nf-5_over_terschelling.jpg)
It just looks like a good dogfighter
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Modern revolver cannons get a higher rate of fire for much less weapon weight then an M61. Especially when you consider that even 2 30mm mounts can weigh less then the single m61 mount.
But the guns are unlikley to be able to sustain that rof and the guns themselves will not last as long as an m61.
Something has to give.
Since they can be fired on que from the avionics and fire 1/2 second bursts thier leathality vs an m61 is not even in the same ball park.
Its hard to imagine something signifigantly more leathal pound for pound then a 6000 rpm vulcan but such things do exist.
As to the 2 m39s in an F5.
I have seen both the F5 and the F18 live fire in real life.
And from 2 km away you can clearly see the slower spool up time of the M61.
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Wheres's tony? The member that wrote that book on aircraft weapons....tony williams or something like that.
Someone go grab him, he knows all these answers.