I didn't want to derail the other thread, but the thought of a plane suddenly weighing 33,000 lbs less made me wonder about how the plane reacts when the bomb is released. I assume it noticeable to the pilots, but does the pilot have to compensate for it? Does the computer account for the change of weight and center of gravity? Is it dangerous?

Any pilots want to satisfy my curiosity?

It buys smaller pants and joins a dating site.

The heaviest object I ever airdropped was a 38,000 pound road grader. It had a fairly long exit time resulting in a very noticeable pitch up as the center of gravity shifted aft. We (E and H model C-130s) never used the autopilot during an airdrop so the pilot had to compensate for the shifting CG and the suddenly lighter aircraft.

No personal experience, but I’d bet that most hard points are near the center of gravity, resulting in minimal to no CG change when a bomb or drop tank is released (empty drop tanks probably have insignificant weight anyway). Basic aerodynamics would lead one to believe that an aircraft would tend to climb with a sudden reduction in weight. This may play right into pulling up and getting as far away from the impending detonation, or the pilot may need to something else to avoid ground defenses.

The far more challenging issue will be a ramp drop as Herkdriver described. First the weight stays the same, but the CG (center of gravity) moves aft, tending to cause a nose up pitching moment that the pilot must override. Then, when the object departs, the aircraft simultaneously becomes lighter by whatever load was lost and the CG snaps forward. I’d guess that folks like Herkdriver develop a touch on the controls that is both very authoritative and subtle/smooth. I’d imagine that a pilot’s fifth ramp drop of a significant weight is probably considerably smoother than his first.

A much smaller scale example of configuration change effecting how the airplane flies is lowering the landing gear on a Bonanza. Something about the way the main gear doors open causes the airplane to “balloon” up if left to its own devices. The first time a pilot drops the gear in a Bonanza it may surprise him. More experienced Bonanza pilots apply control inputs that keep the airplane cruising along straight and level (or drop the gear in a turn where you want a little pitch up anyway). I’d bet that a passenger riding with V-Tail would not ever have a clue that the airplane has such a tendency.

Para definitely has the best answer though.

I seem to recall things being less sluggish and more responsive. I did release a 198 howitzer once with a little tension on the rigging and we shot up pretty good from our hover.

I was in training and I misunderstood the crew chief who instructing and I thought he said to go ahead and release the load when he actually said get ready to release the load. It was only off the deck a few inches, so no damage done. It just bounced around a little.

The hook didn’t shoot up high enough to hit the bottom of the fuselage. The pilots were surprised at the sudden jump in altitude once we were absent 16,000 pounds in the push of a button.

Tony.

It's a bomber, it's designed to offload a bunch of weight in a hurry. From the placement of the bomb racks to the computerized flight controls, I have to think this was something that was a design consideration from the beginning.

quote:

Originally posted by KDR:
I didn't want to derail the other thread, but the thought of a plane suddenly weighing 33,000 lbs less made me wonder about how the plane reacts when the bomb is released. I assume it noticeable to the pilots, but does the pilot have to compensate for it? Does the computer account for the change of weight and center of gravity? Is it dangerous?

Any pilots want to satisfy my curiosity?

Modern planes may compensate some. I think the bombs are carried close to the center of gravity so that there isn't a sudden tendency to pitch up or down.

That is cool info Herkdriver!

quote:

Originally posted by slosig:

A much smaller scale example of configuration change effecting how the airplane flies is lowering the landing gear on a Bonanza. Something about the way the main gear doors open causes the airplane to “balloon” up if left to its own devices. The first time a pilot drops the gear in a Bonanza it may surprise him. More experienced Bonanza pilots apply control inputs that keep the airplane cruising along straight and level (or drop the gear in a turn where you want a little pitch up anyway). I’d bet that a passenger riding with V-Tail would not ever have a clue that the airplane has such a tendency.

Para definitely has the best answer though.

Agree about Para's answer!

With respect to a Bonanza, the CG moves forward very slightly as the landing gear is extended, but this is not really noticeable.

What is noticeable, is the marked increase in drag. When I instruct instrument trainees in Bonanzas, I have them fly to the FAF (Final Approach Fix) with gear retracted, and elevator trim and engine power set to hold level flight at approach speed. Extending the gear at FAF will add just the right amount of drag to cause a descent at approximately 500 - 550 feet per minute, tracking the glideslope of an ILS just about perfectly, almost "hands off," with no change to trim or power. Clients are amazed at how easy it is, with this one simple trick (click-bait?).

quote:

Originally posted by Herkdriver:
The heaviest object I ever airdropped was a 38,000 pound road grader. It had a fairly long exit time resulting in a very noticeable pitch up as the center of gravity shifted aft. We (E and H model C-130s) never used the autopilot during an airdrop so the pilot had to compensate for the shifting CG and the suddenly lighter aircraft.

20 minutes and we have an answer from a guy who's actually dropped that amount of weight from an airplane. This place is crazy amazing.

Ah! So that’s the reason why we’re supposed to stay seated and belted in. No getting everybody to run to the front or back of the 737.

I’ve read that’s how the new officers are broken in while conning the submarine. He/she is trying to get the sub balanced by pumping ballast water. Someone is having some of the crew to sneak to the front or back thus causing issues.
.

quote:

Originally posted by OKCGene:
Ah! So that’s the reason why we’re supposed to stay seated and belted in. No getting everybody to run to the front or back of the 737.
.

One reason, yes.

You get similar effects when dropping mass CDS (Containerized Delivery System--basically supplies) and mass personnel drops. It takes a while for 60 troopers wearing 150ish lbs of gear to run out the aircraft.

I suspect the CG changes for a fighter or bomber are much less dramatic, but you still have weight/mass issues to deal with.

I've spent a big chunk of my career dropping things out of aircraft, from vehicles and large loads to jumpers to space test vehicles, but most of my dropping has been retardant over fires. In some tankers, it's more than 50% of the total weight of the aircraft at the time of the drop.

Depending on the aircraft, what's dropped, and the delivery system, it can make a very significant change in the center of gravity, requiring large control inputs, and in nearly all cases it requires significant forward pressure on the flight controls to force the nose down; the aircraft wants to both climb and accelerate.

In one aircraft I used to fly, a single engine air tanker, turbine PZL M18T, the aircraft was limited to a 15 mph range of airspeed for the drop; below that, it would stall and come out of the air, and above that speed, it would pitch up significantly enough that full control deflection could not put the nose back down; a number of pilots crashed and died when the airplane pitched up, stalled and spun or simply crashed.

On some of the test loads we'd run with various experimental drops, the center of gravity shifts were significant and excessive; a load which would have hung up on it's way out the back of the aircraft would have made the aircraft uncontrollable.

The crash at Baghram air Base a few years ago shows what can happen when weight transfer goes goes bad.

RIP, Crew.

The National 747-400 didn't have a significant shift in CG, as the MRAP that moved didn't have far to go, and it takes a lot more in the 747 to merit a significant change than some aircraft (we didn't have to even change paperwork for anything under 10,000 lbs, or a small CG difference).

The National 747 had a control failure when the MRAP penetrated the aft pressure bulkhead and damaged the elevator trim jack screw. The airplane pitched up and couldn't be controlled.

Worse, airplanes with underslung, pylon-mounted engines experience a pronounced pitch-up with a thrust increase, and as the crew approached a low-airspeed, low energy, high-angle state, their only option would have been to apply maximum or emergency thrust, further pitching up the aircraft. The departure is into rising terrain; big hills around there.

That airplane used to park next to us all the time at Baghram.

National had a systemic problem with the way they operated. It was also a case of a poor safety culture, and a chain of problems. The Boeing load manual was incorrect. National's manual and procedures were incorrect, and the loadmaster didn't follow the incorrect procedures, all of which formed an error chain that lead to a 40,000 lb MRAP moving and penetrating the aft pressure bulkhead.

It's not the first time a penetration of the aft pressure bulkhead, or a failure of that bulkhead, has proven fatal. Failure of that structure caused loss of the vertical stabilizer on a JAL 747 years prior, which subsequently crashed with the loss of all but three lives, as I recall.

I’m amazed by collective knowledge of this place. Thanks herkdriver and sns3guppy

Never dropped that much at once, but dropped a bunch of 500, 1000, and 2000 bombs. This being from a 50-60K airframe. When dropped 1-2 at a time, the 500 was pretty much unnoticeable. The 1000/2000 moved the plane a little, but often you were maneuvering a bit after release, so it really didn't register.

I did a stick of 10 x 1000# in a shallow dive and the bombs alternated from each wing - the plane shook side to side over the release sequence.

Overall pretty benign in comparison to the big boys dropping big stuff out the back.

quote:

Originally posted by r0gue:

quote:

Originally posted by Herkdriver:
The heaviest object I ever airdropped was a 38,000 pound road grader. It had a fairly long exit time resulting in a very noticeable pitch up as the center of gravity shifted aft. We (E and H model C-130s) never used the autopilot during an airdrop so the pilot had to compensate for the shifting CG and the suddenly lighter aircraft.

20 minutes and we have an answer from a guy who's actually dropped that amount of weight from an airplane. This place is crazy amazing.

This! The forum amazes me. A wealth of information and experience here.

Dropping bombs can get perilous too. A friend of mine recently ejected from an A-29 dropping a 500lbs GBU-12 from an outboard pylon. The sudden release of weight caused an asymmetric condition the pilot couldn’t recover from.

quote:

Originally posted by parabellum:
It buys smaller pants and joins a dating site.

And asks his date if she did have a brother, would he like potato pancakes.

LOL