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| Gun Gas Deflectors http://www.warthogterritory.net/forum/viewtopic.php?f=3&t=2401 |
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| Author: | a10stress [ 05 Dec 2002, 08:53 ] |
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I saw mention of the Battelle gun gas deflector on another thread and wonder if I can get clarification on why there was such a push to get this thing to work. Is there anyone who worked flight test or data analysis of this problem in the late 70's early 80's? Here's my recollection from the engineering bias point of view: After the fireball difficulty was fixed with a modified propellant, it was reported that the engines were losing performance because gun gas residue was sticking to the tubomachinery in the engines. Washing these engines was taking up too much maintenence time. I thought it was related to the propellant change, but maybe not? A relativly large effort was launched to fix this gun gas residue problem involving the gun maker (GE, Burlington), airframer (Fairchild), and an outside consultant (Battelle Labs). As an aside, I think GE,Lynn was tasked to help out with engine wash ideas. Fairchild proposed something they had tested in the prototype days we called the "double baffle" deflector. You may have seen pictures of a boilerplate steel flight test version of it installed on a prototype. It was pretty effective at deflecting the gas under the aircraft but it had aerodynamic and weight issues. We didn't want to do it. GE proposed a nice fix that was essentially a bevel at the barrel exit. Maybe they tried several bevel angles? It was partially effective, I think, but changed gun accuracy because the gas deflection induced a sideload on the barrel that set up unpleasant vibrations. Maybe it also changed the bullet trajectory as it exited the barrel. I don't remember many details of this mods performance. We didn't want to do it either but at least it was tolerable. Now about the "Battelle Device". It was the worst performing choice from the beginning. I never understood how it was supposed to function, with its massive spiral shaped muzzle clamp made of Inconel(?). Anyway, this thing must have tuned the gun natural frequencies to an airframe mode or something because the round dispersion went way up. Battelle used the argumment that it was not a bad thing since a larger dispersion meant a higer likelyhood of getting one round on target (huh!). Vibrations were so bad at the low firing rate that it was eliminated. Gun mount loads were horrendous. I think I recall that the gun rate was affected by airspeed because the thing acted like a pinwheel in the airstream, spinning the barrels faster. This thing was universally hated by stress and dynamics because it gave us tremendous problems, and armament could not understand why we were pushing a mod that made the gun less accurate and couldn't use the low rate. And yet this device became the baseline fix and was installed on many jets. We thought Battelle must have friends in high places to keep this project alive. After years in the making, this device just disappeared and we went back to bare barrels. Anybody insiders out there know what happened from another point of view? Mc/I + P/A |
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| Author: | fenderstrat72 [ 05 Dec 2002, 09:55 ] |
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As a Flightline Weapons technican during the time this thing was tested I can tell you it was a piece of junk. It weighs in at about 80-90lbs, it is ugly and never worked correctly. The pilots hated it. More than that Structural damage was being done to the gun bay. I was told it shook the a/c terribly. The device itself was not balanced and the lack of balance caused the gun to vibrate in an unharmonic fashion. These vibrations were transfered to the gun mounts and the whole foward gun bay suffered cracking around the "silver dollar" panels because of it. It looked like a large oil drilling bit. I know the Hog is supposed to be ugly, but this thing made it too ugly. My none engineering opinion was and still is good ridance to bad rubbish. Fender In war there is no prize for runner-up. -- Omar N. Bradley |
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| Author: | D.B. [ 05 Dec 2002, 11:38 ] |
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We had one on our 77-0245. It vibrated badly and broke gun mounts. It never really accomplished anything. This was pre-TEMS so we were washing every 150 hours whether it was needed or not. I know where two diverters are located. One has a trash can sitting on it and the other is being used as an umbrella stand. Cheers db Being responsible means sometimes pissing people off. Gen Colin Powell ret |
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| Author: | 30mike-mike [ 05 Dec 2002, 12:15 ] |
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"...bad rubbish"? "trashcan support"? I'm seeing a pattern, here!<img src=icon_smile_wink.gif border=0 align=middle><img src=icon_smile_big.gif border=0 align=middle> King George II on Gen. James Wolfe: "Mad, is he? Then I wish he'd bite more of my other generals!" |
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| Author: | M21 Sniper [ 05 Dec 2002, 14:24 ] |
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LOL, that must be one of the 10,000 dollar trash cans we keep hearing about! Trample the wounded- hurdle the dead. |
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| Author: | fenderstrat72 [ 05 Dec 2002, 21:11 ] |
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Hey Snipe I believe Dice has one also. I'll bet they cost more than $10,000. Not good for much of anything if you ask me. Fender In war there is no prize for runner-up. -- Omar N. Bradley |
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| Author: | M21 Sniper [ 06 Dec 2002, 06:02 ] |
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LOL, can i get one of those too Fender? I could use a few quality paperwieghts, lol. Trample the wounded- hurdle the dead. |
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| Author: | Weasel [ 06 Dec 2002, 11:35 ] |
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I could use one. Already have part of a wing and the breech end of a barrel. --- Pete Nelson Your Warthog Territory Webmaster |
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| Author: | 30mike-mike [ 06 Dec 2002, 11:40 ] |
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What with all the hot air in this gov't office, I could use one, too!<img src=icon_smile_wink.gif border=0 align=middle> King George II on Gen. James Wolfe: "Mad, is he? Then I wish he'd bite more of my other generals!" |
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| Author: | Dice [ 06 Dec 2002, 11:40 ] |
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Is this the one you're talking about DB...<img src=icon_smile_evil.gif border=0 align=middle><img src=icon_smile_wink.gif border=0 align=middle> <img src="http://hogpen1.tripod.com/bs/divert1.jpg" border=0> <img src="http://hogpen1.tripod.com/bs/divert2.jpg" border=0> Ugly but well hung! |
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| Author: | D.B. [ 06 Dec 2002, 12:21 ] |
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Yep That's it!!!!<img src=icon_smile_big.gif border=0 align=middle><img src=icon_smile_big.gif border=0 align=middle><img src=icon_smile_big.gif border=0 align=middle><img src=icon_smile_big.gif border=0 align=middle><img src=icon_smile_big.gif border=0 align=middle><img src=icon_smile_big.gif border=0 align=middle><img src=icon_smile_big.gif border=0 align=middle><img src=icon_smile_big.gif border=0 align=middle><img src=icon_smile_big.gif border=0 align=middle> Being responsible means sometimes pissing people off. Gen Colin Powell ret |
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| Author: | boomer [ 06 Dec 2002, 12:34 ] |
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HOLY COW!!! LOL "We sleep safely in our beds because rough men stand ready in the night to visit violence on those who would harm us". George Orwell Fighting For Justice With Brains Of Steel ! <img src="http://www.fas.org/man/dod-101/sys/ac/atengun2X.GIF" border=0> |
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| Author: | 30mike-mike [ 06 Dec 2002, 13:23 ] |
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Jumpin' Jehosephat!<img src=icon_smile_shock.gif border=0 align=middle><img src=icon_smile_approve.gif border=0 align=middle> King George II on Gen. James Wolfe: "Mad, is he? Then I wish he'd bite more of my other generals!" |
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| Author: | fenderstrat72 [ 06 Dec 2002, 15:53 ] |
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Told ya the thing was huge and ugly. It was safety wired with .50th saftey wire. Just try to safety wire something with a coat hanger and you will get the picture. Fender In war there is no prize for runner-up. -- Omar N. Bradley |
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| Author: | D.B. [ 06 Dec 2002, 18:25 ] |
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Good thing my wife hasn't seen this or she'd have that thing tied to my back end. <img src=icon_smile_big.gif border=0 align=middle> Being responsible means sometimes pissing people off. Gen Colin Powell ret |
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| Author: | a10stress [ 06 Dec 2002, 19:46 ] |
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So the mystery still exists. Why did we have to waste our time and the taxpayers' money on that monstrosity? And how did it manage to avoid a "golden fleece" award? Where are the project killers when you need them? That being said, it sure makes a neat piece of trashcan art. Mc/I + P/A |
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| Author: | FlyBoy [ 07 Dec 2002, 20:37 ] |
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<img src=icon_smile_shock.gif border=0 align=middle> is that all one casting? That thing looks like it weighs a ton! A Proud Ambulance Rider! EMS |
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| Author: | the pope [ 08 Dec 2002, 03:43 ] |
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nice rubbish bin! <img src=icon_smile_wink.gif border=0 align=middle> pope |
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| Author: | fenderstrat72 [ 09 Dec 2002, 10:51 ] |
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Flyboy it is not a single casting. As a matter of fact it is not cast at all. It was welded together from several pieces and yes it is very heavy. Like I said previously in this thread it was around 90lbs. Piece of junk is all it was. Fender In war there is no prize for runner-up. -- Omar N. Bradley |
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| Author: | plane_mc [ 09 Dec 2002, 11:16 ] |
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Hey Dice, I could sure use 1 of those. <img src=icon_smile_big.gif border=0 align=middle> It would really look good in my office. <img src=icon_smile_wink.gif border=0 align=middle><img src=icon_smile_wink.gif border=0 align=middle> plane_mc |
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| Author: | epkpctech [ 17 Dec 2002, 08:07 ] |
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I started working on the Hog at MBAFB and I worked in Panther Phase dock. I can not tell you how many times planes were late in leaving the dock due to cracks just below the ladder door. As a A1C I could tell that this "Hunk of Junk" would not work. Pete Kesseler |
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