Voidhunger Posted February 10, 2014 Posted February 10, 2014 Has anyone managed to damage undercarriage of the enemy planes? Is this DM modeled? I haven´t been so lucky so far. (only shot-off undercarriage). 1
Finkeren Posted February 10, 2014 Posted February 10, 2014 I don't think the DM incorporates the hydraulic/electrical systems (yet) but it is definately posible for the undercarriage to suffer mechanical damage and get stuck. It has happened to me a few times, where I started retracting the undercarriage too early before the plane had properly left the runway and ended up with one leg stuck in a halfway-down position.
Fragal Posted February 10, 2014 Posted February 10, 2014 Something like this?The left strut was still attached only the wheel came off 1
Voidhunger Posted February 10, 2014 Author Posted February 10, 2014 maybe I meant hydraulic/electrical systems.
Finkeren Posted February 10, 2014 Posted February 10, 2014 I do hope that these systems become part of the DM at some point - if necessary after release. It will be rather important in the case of the Yak-1. All Yaks had pneumatically operated gear and flaps. It was a system that weighed less but was also far more succeptible to damage, leading to a lot of belly landings.
smink1701 Posted February 10, 2014 Posted February 10, 2014 I would like to see a wheel drop due to hydraulic/electrical damage. I've seen this many times in gun cam footage so I think it must have been a common occurrence. 1
FuriousMeow Posted February 10, 2014 Posted February 10, 2014 I doubt damage to the electrical system would the gear to drop. Pneumatic/hydraulics yes, because a leak causes the pressure to disappear that is keeping the landing gear retracted. The electrical system would just not allow the gear to extend.
69th_chuter Posted February 13, 2014 Posted February 13, 2014 I doubt damage to the electrical system would the gear to drop. Pneumatic/hydraulics yes, because a leak causes the pressure to disappear that is keeping the landing gear retracted. The electrical system would just not allow the gear to extend. Hydraulic and pneumatic actuated gear is/was almost always held by an uplock, early D Mustangs excepted (later retrofitted with uplocks). It would take pressure (or mechanical actuation) to unlock and drop the gear ... OR, maybe a direct strike on the lock.
DD_bongodriver Posted February 13, 2014 Posted February 13, 2014 How was the uplock activated? some aircraft it was simply a latch that automatically locked the gear, others were fully sequenced.
FuriousMeow Posted February 14, 2014 Posted February 14, 2014 Hydraulic and pneumatic actuated gear is/was almost always held by an uplock, early D Mustangs excepted (later retrofitted with uplocks). It would take pressure (or mechanical actuation) to unlock and drop the gear ... OR, maybe a direct strike on the lock. Well, I wasn't really specific towards negative pressure or positive pressure. It's an enclosed system. So once it becomes compromised it no longer works as it should, which would lead to issues like gear dropping when the system is shot through.
Crump Posted February 20, 2014 Posted February 20, 2014 (edited) If you have ever done aerobatics in an complex aircraft then you know the uplocks release quite easily. Damage to the hydraulic system would cause the gear to droop. In fact several complex aircraft use the lack of hydraulic pressure as the emergency gear release. You simply pull a lever which opens a relief valve to take pressure off the system and gravity extends the gear. Many complex aircraft will give you a transition light in steep turns. Edited February 20, 2014 by Crump
Obelix Posted February 20, 2014 Posted February 20, 2014 I have just managed to destroy mine, in LaGG 3. I made a "touch and go" a little bit hard, and my landing gear stayed on the landing trip... 1
69th_chuter Posted February 20, 2014 Posted February 20, 2014 (edited) On the planes I'm directly familiar with, the hydraulic gear emergency release won't work unless the gear handle is DOWN to unlock the uplock. So gear extension on planes so equipped would require damage to both the hydraulic actuation and uplock systems. With some electric gear like on the Bonanza there is no uplock (the actuator reduction gear preventing extension), but the 190's gear has a separate, manually operated upluck (just outboard of the inboard guns on the spar), as the gear's electric actuator motor is unclutched when not running, so to get its gear to drop by damage requires only damaging the uplock. So, apparently, a working knowledge of each type aircraft's systems is needed to make a realistic damage model (really? omg! lol). :D The D Mustang (D-1NA through first 200 D-10NA, no Dallas aircraft) originally ditched the uplocks of previous models to simplify the system but high loads tended to droop the gear with disastrous results forcing a retrofit. Edited February 20, 2014 by chuter
Crump Posted February 21, 2014 Posted February 21, 2014 the hydraulic gear emergency release won't work unless the gear handle is DOWN to unlock the uplock Most uplocks are hydraulically activated. When the hydraulic system loses pressure, the uplocks release. The most common method of emergency gear extension is gravity assisted by releasing the hydraulic pressure. It was common for World War II fighters to experience partial or total gear extension when the hydraulic system took damage resulting in a loss of hydraulic pressure.
Crump Posted February 21, 2014 Posted February 21, 2014 Here is electrically operated gear failing due to damage. http://cdn.theatlantic.com/static/infocus/ww2_9/s_w12_05010145.jpg Landing gear systems are designed to default to the down position if a failure in the system occurs. That is why the most common method of emergency extension is gravity.
Sternjaeger Posted February 21, 2014 Posted February 21, 2014 (edited) ^ What Crump said. I've seen the Buchon "109" in Duxford popping its landing gear out whilst pulling out of high-G manoeuvres in a couple of occasions: it's just simple physics, the landing gear will tend to want to open just under its sheer weight, add a bit of load to it, and voila'.. Some of the earlier designs didn't rely on latches because they failed, and you ended up having to belly land a perfectly functional aircraft just because a tiny latch failed. Things got better over the years, but despite the modern technologies and construction methods used today, door latches can still be an issue, and I'm not talking just about small aircraft. Edited February 21, 2014 by Sternjaeger
StrIke Posted February 21, 2014 Posted February 21, 2014 (edited) Some uplock systems have a backup spring that will keep the uplock in place and allow you to isolate the landing gear system from the main hydraulic system whilst flying. In any event that the gear system is damaged, you wont drain the entire hydraulic system. This means that if you loose your hydraulic system that normally operates the gear, you need a backup system to overcome the spring tension in the uplock mechanism to release the gear. Then the gravity of the gear will make it extend, and a downlock spring will engage it in a over-center fashion once it's fully extended. Similar to when you're standing, your knees will move back (over center) and lock your legs so your muscles can relax more. Ref : F-16 A trick we used to do back in school was to walk over to an unsuspecting friend who is standing and talking to someone. Find out which leg he/she is leaning their weight on and use your knee to poke them gently behind their knee. They may sometimes fall unsuspectingly to the ground due to their poor reflexes and "downlock failure" - ninja Edited February 21, 2014 by StrIke
69th_chuter Posted February 21, 2014 Posted February 21, 2014 Most uplocks are hydraulically activated. When the hydraulic system loses pressure, the uplocks release. The most common method of emergency gear extension is gravity assisted by releasing the hydraulic pressure. It was common for World War II fighters to experience partial or total gear extension when the hydraulic system took damage resulting in a loss of hydraulic pressure. "You can release the landing gear in an emergency by means of a red handle just above the hydraulic pressure gage. Pulling this red handle releases the pressure in the hydraulic lines. This allows the gear to drop of it's own weight when the landing gear handle is in the DOWN position. The landing gear lever must be in the DOWN position - all the way down - or the mechanical locks which hold the gear in place are not unlocked." P-51 Mustang Pilot's Flight Manual page 17. The Mustang literally had wings torn off when the (unlocked) landing gear drooped out of the wells at speed (killing pilots) so the design quickly reverted to the mechanical uplock system it had previously. This type system is common on all the American warbirds I'm familiar with. For instance, the Hellcat's emergency extension T handle simultaneously released the hydraulic system, closed the vent valve in the air system, opened the air bottle valve and released the uplocks. Having the gear come down at the wrong time simply because of a loss of hydraulic pressure could be fatal, as in the case of the Mustang, or simply disastrous, in the case of the Hellcat, if trying to escape a chasing enemy. As an airplane mechanic (who flys for fun - at $5.75 a gallon - HA) I only really know what I work so it's basically American systems ... although I'm somewhat familiar with German systems, not at all with WW2 Russian and I've heard from somewhere that the British may have used peek-a-boo wheels too ... that's what I know. For that 190, though, the leg's electric motor is unclutched when not running (at about 10,000rpm) so it isn't helpful in holding up the gear ... at all ... so all it would take to drop that gear is damage to the mechanical uplock.
69th_chuter Posted February 21, 2014 Posted February 21, 2014 I've seen the Buchon "109" in Duxford popping its landing gear out whilst pulling out of high-G manoeuvres in a couple of occasions: it's just simple physics, the landing gear will tend to want to open just under its sheer weight, add a bit of load to it, and voila'.. That's interesting. I know the 109 has an uplock, it's at the aft outboard end of the leg well and and protrudes into the well with the hook swinging outboard. It catches a tiny, wimpy looking, actually, roller on the aft side of the gear just above the top of the tire. For being a HUGE 109 fan I sure don't know very much about its systems, but I do know the difference in speed between landing gear doors on and off ---> 8 kph. (Did that have any bearing on anything? )
Crump Posted February 21, 2014 Posted February 21, 2014 Chuter says: The landing gear lever must be in the DOWN position - all the way down or Chuter says: the mechanical locks Will not release.... Mechanical locks are not the same as: Crumpp says: Most uplocks are hydraulically activated. What will happen on a P-51 is the inner gear doors will drop even if the uplocks are not damaged and manage to hold. I would expect the uplocks to hold under level flight and gentle maneuvering. Hard maneuvering they will fail to hold the gear in and of themselves. Uplocks are not the solid locking system you seem to think, just ask any owner of a fully aerobatic complex aircraft. Gear systems are designed to default to the down position. In the multiple gear up landings I have repaired, only once was it a failure of the gear operation. In that case, a nose gear door hinge broke and wedge the nose gear in the up position. The pilot landed on main's with the engine shut down and the propeller horizontal. Strike says: Some uplock systems have a backup spring that will keep the uplock in place and allow you to isolate the landing gear system from the main hydraulic system whilst flying....... The developers need to refer to the specific aircraft maintenance manual. 1
Crump Posted February 21, 2014 Posted February 21, 2014 (edited) For that 190, though, the leg's electric motor is unclutched when not running (at about 10,000rpm) so it isn't helpful in holding up the gear ... at all ... so all it would take to drop that gear is damage to the mechanical uplock. It is not unclutched. The motor drives a rotating gears in a housing that ratchet the gear up and down. The motor is switched off as are all electric motors when not in use, otherwise they would burn up. Just replaced two flap motors on the BE90 I fly because the limiter switch was bad and not turning the motor off. It is still drives the housing and that is why the FW190 has a sealed air jack to assist the gear down when the pilot pulls the manual uplock release for emergency gear extension. Edited February 21, 2014 by Crump
Sternjaeger Posted February 22, 2014 Posted February 22, 2014 What will happen on a P-51 is the inner gear doors will drop even if the uplocks are not damaged and manage to hold. I would expect the uplocks to hold under level flight and gentle maneuvering. Hard maneuvering they will fail to hold the gear in and of themselves. Uplocks are not the solid locking system you seem to think, just ask any owner of a fully aerobatic complex aircraft. I'm not sure I understand what you mean there?
MiloMorai Posted February 22, 2014 Posted February 22, 2014 He means the inner gear doors will drop into the airstream and be ripped off.
Sternjaeger Posted February 22, 2014 Posted February 22, 2014 He means the inner gear doors will drop into the airstream and be ripped off. mmmh hardly, the Mustang locks are quite well designed..
Crump Posted February 22, 2014 Posted February 22, 2014 (edited) On the full size P-51, when at rest, the doors droop down under their own weight, only retracting to their normal closed position when hydraulic pressure rises upon engine start. http://www.rcscalebuilder.com/tutorials/gear_doors/ The Mustangs inner gear doors are held up by hydraulic pressure. There is no lock. They will droop down under their own weight as the aircraft sits. It is something Mustang owners are familiar with..... Losing hydraulic pressure in flight will cause the inner gear door to drop down. Here you go....watch the inner gear doors..... http://www.youtube.com/watch?v=wdy17GmkpWc Thanks for the real-world expertise Crump. You are welcome. Thanks for appreciating it. We are still restoring a Mustang as a dual control bird. Edited February 22, 2014 by Crump
Sternjaeger Posted February 22, 2014 Posted February 22, 2014 (edited) Crump, I'm afraid you have no idea what you're talking about. The P-51D has up-locks that engage with both the landing gear AND clam doors. Once you activate the landing gear lever, the lock mechanism (which is a spring loaded one and connected to the landing gear lever in the cockpit), disengages, leaving the landing gear doors to do a full cycle (fully open, then once the gears are up and locked, up again because of hydraulic pressure) and the landing gear to come down. At that stage the only thing keeping the doors up is the hydraulic pressure, NOT the locks, that's why when you switch the engine off pressure will bleed and so will the clam doors. But as long as the gears are up, the locks will keep both gears and doors locked in closed position. Edited February 22, 2014 by Sternjaeger
Sternjaeger Posted February 22, 2014 Posted February 22, 2014 (edited) It is something Mustang owners are familiar with..... You are welcome. Thanks for appreciating it. We are still restoring a Mustang as a dual control bird. ..you might want to get yourself a better maintenance manual Edited February 22, 2014 by Sternjaeger
MiloMorai Posted February 23, 2014 Posted February 23, 2014 What will happen on a P-51 is the inner gear doors will drop even if the uplocks are not damaged and manage to hold. The Mustangs inner gear doors are held up by hydraulic pressure. There is no lock. They will droop down under their own weight as the aircraft sits. It is something Mustang owners are familiar with..... Losing hydraulic pressure in flight will cause the inner gear door to drop down. Please make up your mind Crump about there being inner gear door locks or not. mmmh hardly, the Mustang locks are quite well designed.. Be sure, or there would have been multiple crashes/damage reports like there was for the u/c.
Venturi Posted February 23, 2014 Posted February 23, 2014 The first quote, he is talking about the main gear uplocks, and that there is no door lock. The second quote is consistent with that. Sternjaeger is the one saying that the gear uplocks also lock the inner door, MiloMorai.... The bottom line is (that is relevant to the original question), whether the a/c has gear locks or not is probably aircraft specific, but regardless, certainly hydraulic failures contributed to gear drops on numerous aircraft in ww2 battles as shown by gun footage. I think Crump made it clear that the devs need to reference the original sources for each particular plane as to the design of the uplocks, if present, to determine if said mechanisms could totally prevent the gear dropping even with hydraulic pressure loss.
Sternjaeger Posted February 23, 2014 Posted February 23, 2014 (edited) Yes, that's why I agreed with Crump's first post. His strong assertions on the Mustang "that any Mustang owner should know" are wrong (which is even more puzzling, coming from a qualified aircraft mechanic allegedly working on a Mustang). Once again there is no need to try and impress people, this is not a competition.. Back to the OT, it's obviously an aircraft-specific thing, but bear in mind that loss of hydraulic pressure doesn't automatically mean landing gears dropping, that's the whole purpose of the up-locks. What can happen is that the doors could open (if they don't have up-locks) and you could have a partial extension of them, or if you have been hit on the locks AND are losing hydraulic pressure, then the gears will come down. In any case, it's a bad bad sign for your aircraft! Edited February 23, 2014 by Sternjaeger
69th_chuter Posted February 23, 2014 Posted February 23, 2014 (edited) It is not unclutched. The motor drives a rotating gears in a housing that ratchet the gear up and down. The motor is switched off as are all electric motors when not in use, otherwise they would burn up. Just replaced two flap motors on the BE90 I fly because the limiter switch was bad and not turning the motor off. It is still drives the housing and that is why the FW190 has a sealed air jack to assist the gear down when the pilot pulls the manual uplock release for emergency gear extension. Well, a very good design analysis by Chester Ricker of the 190 that was published during 1945 in Aviation magazine includes a breakdown on page 29 of the very ingenious 10,500 to 1reduction gear (no gear cutting, can be made with grinder, lathe and drill press) would seem to indicate otherwise, at least when it comes to a completely different aircraft. To quote from page 30: "There is a 3.3-to-1 reduction in the motor head so that shaft extending from the motor runs about 3,200 rpm. On this are mounted two cast iron shoes, driven by a cross pin and held in place by a continuous coiled spring band. The latter is stiff enough to hold the shoes in place and to resist centrifugal force so as to allow the motor to attain considerable speed before the shoes engage a surrounding drum of steel. This gives an automatic clutch effect." What is being described here is a centrifugal clutch, so, yeah, it would have a clutch effect - lol. It then goes on to describe the rest of the gear reduction design. Seriously, though, this is a great article on the whole 190. Highly recommended and can be found at: http://legendsintheirowntime.com/FW190/FW190_Av_4410_DA.html This is an all text page, skip it (I have aspergers, I can get bored easily without pictures - LOL). Instead, go all the way to the bottom and open the .pdf, it has the article with all the pictures and illustrations. Edited February 23, 2014 by chuter 1
Crump Posted February 23, 2014 Posted February 23, 2014 I did not say it did not have a clutch.....I said it is not unclutched when the motor is shut down. Two different things.....chuter. What do think automatic clutch effect means, mechanic?
Sternjaeger Posted February 23, 2014 Posted February 23, 2014 Crump, you really have an attitude problem man...
Bearcat Posted February 23, 2014 Posted February 23, 2014 I refuse to edit this thread.. if it goes farther south it will just be locked. 1
Crump Posted February 24, 2014 Posted February 24, 2014 Well, a very good design analysis by Chester Ricker of the 190 that was published during 1945 An even better one was published by Focke Wulf GmbH.
Crump Posted February 24, 2014 Posted February 24, 2014 Sternjaeger is the one saying that the gear uplocks also lock the inner door, MiloMorai.... No, the inner gear door have their own latch system that is separate from mains. Like all retractable gear, it is designed to default to the down position.
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