Guest Dirt Beater Posted March 10, 2004 Posted March 10, 2004 In the pointy-nose world, how often do over-G's happen? What are the ramifications for the pilot? The beer to the MX guys goes without saying...
Guest egghead Posted March 10, 2004 Posted March 10, 2004 Depends on how serious the over G was. With just a class one on 16's (about .2 G over) Some minor inspections are required. Removing panels getting a mirror and a flashlight. All in all only about 2-4 hours of work. Beer aside I don't know of anything that happens to the pilot. One LT here had two over G's in just as many weeks. Besides being on a first name basis with the class six I don't know of anything else. Ops folks will be able to chime in on thier own side. On more serious over G's more in depth and time consuming inspections are requied. Might even go up to depot level if it's bad enough. [ 09 March 2004, 20:09: Message edited by: egghead ]
Guest CBStud Posted March 10, 2004 Posted March 10, 2004 In the T-38C over G's are more common than you'd think. It happens esspecially on solo rides. The computer senses all this stuff to compute the G limit and if your even close to max G and pulse the stick quickly it'll give you an over G. What usually happens is you burn down gas, and if you don't have any controlability issues you just head back home and fly a straight-in. The beer payment is standard. I can't tell you for the Fighters but I'm pretty sure the computer onboard the 16 won't let you over G.
Guest egghead Posted March 10, 2004 Posted March 10, 2004 Originally posted by CBStud: In the T-38C over G's are more common than you'd think. It happens esspecially on solo rides. The computer senses all this stuff to compute the G limit and if your even close to max G and pulse the stick quickly it'll give you an over G. What usually happens is you burn down gas, and if you don't have any controlability issues you just head back home and fly a straight-in. The beer payment is standard. I can't tell you for the Fighters but I'm pretty sure the computer onboard the 16 won't let you over G.The computer will let you over G
Guest TimN88 Posted March 10, 2004 Posted March 10, 2004 Whats the maximun G's that the t-38 is rated for? Also, what kind of training and testing do pilots go through to see if they can handle G's? do they put you in a big centerfuge and spin you around?
Guest Dirt Beater Posted March 10, 2004 Posted March 10, 2004 The 'Fuge...A Trip to 9Gs at Holloman AFB, NM Pretty gnarly stuff...
Toro Posted March 10, 2004 Posted March 10, 2004 Originally posted by Dirt Beater: In the pointy-nose world, how often do over-G's happen? What are the ramifications for the pilot?I'd say we average around one a week in my squadron. You can actually over-G the Strike Eagle and continue the mission in some cases - provided the over-G wasn't on one of the jet's mass items, and it doesn't exceed a certain percentage of overload. If you over-G, you buy a CD for the bar - and yes, the WSO has to buy one as well. If it's a severe over-G, you may find yourself pulling panels with the maintainers in addition to buying them a case of beer. Originally posted by CBStud: What usually happens is you burn down gas, and if you don't have any controlability issues you just head back home and fly a straight-in. Does the student hook the ride? Used to be any over-G was an automatic hook. I can't tell you for the Fighters but I'm pretty sure the computer onboard the 16 won't let you over G.The Strike Eagle has a system that warns you when you’re about to over-G. It has a beeper that starts up when you’re at 85% of your max allowable G, then a more rapid beeper that kicks in when you’re at 92%. My understanding of the viper was that it was a limiter which won’t allow you to over-G in normal circumstances, but with external stores, the limiter in some case will allow an over-G.
Guest 15chief Posted March 10, 2004 Posted March 10, 2004 There are 3 levels of over Gs. 1 being the lowest and three being the highest. I've had my jet come back with a level 1 on several occasions. Level 1s aren't too bad. They require only a few more insp than your typical post flight insp. Level 2s & 3s on the other hand are an entirely different story. At these levels there can be some significant airframe damage. At my unit,any over G above level 1 equals a case for the crew chief. There was a 2LT who brought back the jet with a level 3 over g. Both engines had to be removed a number of man hours were spent on inspections. Our commander ordered the LT to assist the mechanics. We took a great picture of a pilot in his flight suit turning a speed handle.
BFM this Posted March 10, 2004 Posted March 10, 2004 If my understanding of legend is correct, over-g is where we get things like static displays and aircraft at maintenace schools.
Guest CBStud Posted March 10, 2004 Posted March 10, 2004 "Whats the maximun G's that the t-38 is rated for?" The book says max is 7.33. I guess that's the max G with no gas because at 1,000lbs and below it's 7.2 G. I don't know if its the same with all the other jets but the max G is constantly determined by how much gas is on board. Heavy weight we can only get up to 5.8. "Does the student hook the ride? Used to be any over-G was an automatic hook." Yea Toro, over G's still is a hook. Solo's can't get away with it anymore either because the jet saves that kind of information. The 38C now has that same beeper at 85 and 92%
Guest Dirt Beater Posted March 10, 2004 Posted March 10, 2004 Okay, here's part deux...what are the most common reasons for over-G'ing the jet? Avoiding the dirt? Too much beer money? Thanks
Hacker Posted March 11, 2004 Posted March 11, 2004 Originally posted by Dirt Beater: what are the most common reasons for over-G'ing the jet? Avoiding the dirt? Too much beer money?Generally it's ham-fisted pilots.
Guest Patriot 328 Posted March 11, 2004 Posted March 11, 2004 How many G's are guys pulling to pull the level 3 over G on an Eagle? I would think the aircraft can handle more than the airman. Are these G limits flat limits for a given configuration or are they relative to the payload and/or speed? I know transport category aircraft are simply structural limitations. And any real maneuvering is performed at or below Va. (i.e. stall before any airframe damage) Are we talking about yanking and banking at the wrong speeds in training?
Guest TimN88 Posted March 11, 2004 Posted March 11, 2004 Wouldnt the G rating for an airframe also be somewhat conservative to introduce a safety margin? If a t-37 is rated to 7.33, then an eagle is probably what, 8.5 or over? I have no idea what that would feel like, but im assuming its pretty painful, right? As patriot328 says, wouldnt todays jets be capable of more than a trained pilot can hande? I know extra 300's are rated to +/-10. How many pilots could actually handle that for a significant amount of time?
Guest Flysh Posted March 11, 2004 Posted March 11, 2004 about human tolerances, sean tucker flys a modded pitts S2 in airshows and its said that he withstands +12 to -7 G during his routine.
Toro Posted March 11, 2004 Posted March 11, 2004 Originally posted by Dirt Beater: Okay, here's part deux...what are the most common reasons for over-G'ing the jet?Before the C model, the most common reason for over-Ging the 38 I experienced was flying through jetwash while pulling G (now you have to apply asymmetrical G limits). Not sure if this is something the C model can compensate for, but it sucks to have it happen. We had a student flying his first (of only four) FM rides and he flew through the other guy's jetwash while doing the G exercise. He hooked the ride, obviously got nothing out of it, and only had three left after that. In the Strike Eagle, I've most commonly seen the jet over-G'd at the beginning of BFM setups. Both jets are at 430 knots and striving to pull as close as possible to 9Gs when they go into their break turn. Throw a little bit of asymmetry into your break turn and it decreases your G available - I know a guy who over G'd at 5Gs. Originally posted by Patriot 328 How many G's are guys pulling to pull the level 3 over G on an Eagle? It’s not a specific amount of G, but rather a percentage of overload on the aircraft components that designates what level the over-G is. Generally, with a straight pull in standard configurations, pulling 9.0 Gs at lower to medium altitudes will give you 100% overload (not an over-G, but damn close). Throw in a little asymmetry, or higher altitudes/faster airspeed and your G available decreases. So a 7.0 G pull could now give you 101%, which is a Level 1 over-G. 111-120% is a level 2, 121-130% is a level 3, 131-140% is a level 4, and anything above 141% is a level 5…and that plane probably isn’t coming home. I would think the aircraft can handle more than the airman. Are these G limits flat limits for a given configuration or are they relative to the payload and/or speed? Nope, 9Gs is where it maxes out. Yes, this depends on not only configuration, but also weight, altitude, and airspeed. The jet has an Overload Warning System (OWS) which computes the amount of G the jet has available based on these factors. If you are at higher altitudes and/or faster airspeeds, your G available decreases to less than 9. The 85 and 92% beepers talked about earlier are computed by the OWS. [ 11 March 2004, 01:02: Message edited by: Toro ]
Hacker Posted March 11, 2004 Posted March 11, 2004 Originally posted by Flysh: about human tolerances, sean tucker flys a modded pitts S2 in airshows and its said that he withstands +12 to -7 G during his routine.These are instantaneous Gs, though. A Viper in a 180-degree 9G sustained turn puts it's pilot through significantly more stress than Sean Tucker spiking 12 in a snap roll. The human body can sustain lots of instantaneous G in the Z-axis (just look at ejections, people falling off buildings and living, etc) -- but the physiological concern is can the pilot *sustain* that kind of G and still function.
Guest Flysh Posted March 11, 2004 Posted March 11, 2004 ah i understand hacker, thx for clarifying for me
Riddller Posted March 11, 2004 Posted March 11, 2004 Uhh, might be a dumb question, but what does "hooking the ride" mean? Also, when you talk about adding in some "asymmetry" while pulling g's, what does that mean? Thanks!! :D
Guest Infinotize Posted March 11, 2004 Posted March 11, 2004 "Hooking" is failing a check ride. As for asymmetry, I can't help you out on that one!
C17Driver Posted March 11, 2004 Posted March 11, 2004 Actually, "hooking" is failing any ride, test, etc...not just checkrides.
Flare Posted March 11, 2004 Posted March 11, 2004 Originally posted by Riddller: Uhh, might be a dumb question, but what does "hooking the ride" mean? Also, when you talk about adding in some "asymmetry" while pulling g's, what does that mean? Thanks!! :D I'll give asymmetry my best shot, and someone else can clarify me if they have a better way to put it. As long as you are only pulling back on the stick (sts) then it is symmetric. But if you are actively rolling (either by aileron or rudder) while pulling, that would be asymmetric due to the uneven lift being produced by the 2 wings. You could even be in a bank and turning(say a 60-degree bank) and as long as you were only applying back stick pressure, that would be symmetric, but as soon as you had input any rolling motion, it then becomes asymmetric. As Toro said, the asymmetric g's generally present the most problem because they are quite lower than normal limits. For example , if you were approaching a normal bingo fuel in the -38, then your limits would be about 7 g's, but the asymmetric limits would still be about 4.8ish which is very easy to over-g. [ 11 March 2004, 16:27: Message edited by: ENJJPT stud ]
Guest mcclesm Posted April 13, 2004 Posted April 13, 2004 I just found this old thread, and it spiked my interest, because I am quite involved (on the maintenance side) in T-38 over Gs. I'm an active duty T-37/T-38 structural engineer, and one of my main projects is restructuring the Over G inspection. This won't change the max limits (7.33/-3Gs) but will make the over G dependant on the flight condition. Currently, an over G is an over G, and the same long and tedious inspection is done no matter what. (An over G is dependant on fuel weight and symmetrical/ unsymmetrical flight). We are changing the criteria so that an over G is also dependant on other factors, such as accelerated roll rate/ unaccelarated roll, altitude, and Mach number. The bottom line is, it may not be as "easy" to over G a T-38 in the future, and the long inspection is only necessary in the most extreme over Gs. Unfortunately, this information is only recorded on the C models. But eventually, that's all there will be.
Guest wms Posted April 13, 2004 Posted April 13, 2004 At 'Spang around '86 there was a Phantom that had tape left in the bellows tube which allows ram air to increase stick pressure with airspeed. I don't remember the amount of pos & neg g's but they were enough that when the pilot initiated an offensive maneuver the engine mounts broke and the horz stab warped. The WSO was also taken to the hospital for a back injury.
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now