Why are the engines on the F-18 so close??

[Whatsisname]

Yep, "supercruise" they call it.

 

[Broadsword2004]

I hope the Marines get the V-22 Osprey and I hope the Air Force gets the F-22. Both those aircraft I think are very important for the future. The F-15 and F-16 both fell under heavy criticism in their early days as well, I believe.

So did the Bradley Fighting Vehicle, the Abrams tank, and the Apache helicopter.

 

[Schnugg]

First off, as I'm sure Schnuggapup will confirm, Top Gun was anything but accurate. Only in the details, though (like tapping the gas gage on low fuel?? good one).

Hard as it is to believe...tapping a gauge (analog not digital) did sometimes help if a cannon plug was loose on the back of it. Sometmes worked on old Grumman products I flew.

r/
G

 

[PropStop]

Hard as it is to believe...tapping a gauge (analog not digital) did sometimes help if a cannon plug was loose on the back of it. Sometmes worked on old Grumman products I flew.

r/
G

Fuel gauge malfunction in a P-3 procedure:

1 - Test - press test button
2 - TAP - lightly tap on gauge
3 - Check - the circuit breaker.

 

[Schnugg]

Fuel gauge malfunction in a P-3 procedure:

1 - Test - press test button
2 - TAP - lightly tap on gauge
3 - Check - the circuit breaker.

PropStop nailed it....I love it when it's actually called out in the procedure to tap the gauge. See the attachment.

r/
G

 

[A4sForever]

OBTW, F/A-18 handles single engine very nicely. Like an A-4 I've been told......

That must be bad gouge .... we used to fight F'in/A-18s in the Scooter on a regular and frequent basis when those old A4's and their even older A4 drivers filled the tactical frequency with "guns kill" and "Fox 2" calls .....

Of course, we were still sitting in the chocks --- :icon_wink

 

[Schnugg]

Some aircraft, however, do not have ailerons (the B-52 for example). To turn they put the spoilers up on one side which spoils the lift on that side, dropping the wing and now you've got angle of bank and you're in a turn.

on aircraft like the f-18 the whole horizontal stabilizer moves vice just the elevator at the aft end of it. When the whole control surface moves and has no subcomponent (like the rudder or elevator) it is called a stabilator, because it serves the functions of the stabilizer and the control surface. Instead of changing the camber of the surface to create or spoil lift, stablilators change their angle of attack and litterally fly the tail up or down (or side to side) just like the main wing does. This is also called a "Flying Tail" and was a critical break through in highly maneuverable aircraft and transonic aircraft.

The F-14 has spoliers (4 on each wng) as well, no ailerons at all. We use our differential tails and spoliers to roll. One drawback is when you make a quick stick input on the ball, the spoilers destroy some lift which is not what you want, so every lateral stick moevement is typically accompanied by a power change. Not so in all aircraft.

cheers,
G

 

[kmac]

Schnuggapup-
What exactly is the difference between loss of lift via spoilers and that of ailerons on the downward moving wing? I suppose the issue would be the upward moving wing, seeing that with ailerons additional lift is generated. I was always under the assumption that any aircraft would require a power increase (given a centered ball, correct initial power input) with any roll. Am I wrong?

 

[A4sForever]

Kmac:
I ain't "Schnuggapup", but I can give you some insight into your question from two viewpoints:

1. Dive bombing
2. Landing on the carrier

Let me know if you want a post on the non-aileron aircraft ... it might take a little back-and-forth to get the idea. But then you are probably smarter than me and will get it quick .......

By the way ... Merry Christmas, guys.

 

[PropStop]

Schnuggapup-
What exactly is the difference between loss of lift via spoilers and that of ailerons on the downward moving wing? I suppose the issue would be the upward moving wing, seeing that with ailerons additional lift is generated. I was always under the assumption that any aircraft would require a power increase (given a centered ball, correct initial power input) with any roll. Am I wrong?

When you use ailerons they work as a pair. One wing gains lift when the aileron moves down and increases that wing's camber, the other wing looses lift as the aileron moves up and that wing drops. With spoilers one wing's lift is reduced, "spoiled" if you will, and it drops - there is no effect on the other wing. In both of these cases the lift vector is changed from straight up (countering gravity) to an angle, resulting in less lift to counter gravity. Now, as you change your vector from straight up to an angle you loose some of the energy that is countering gravity and you either descend or slow down.

When a P-3 is on station at 200' we fly what's called "loiter" airspeed. Loiter is based on the aircraft gross weight, so it changes as we burn down fuel. When we turn sharply (we frequently go to 45AOB) we bleed off a fair amount of airspeed, 10-15 kts. We could add power to prevent us from bleeding off this energy, but that'd screw up our fuel planning so we accept it. Other times, when we want to maintain airspeed through a turn, we'd add power. When the P-3 initially starts a turn it actually has a tendency to climb before it descends due to loss of that upward lift vector.

I don't know why certain aircraft use spoilers exclusively in place of ailerons. I guess in the case of the F-14 the roll action is accomplished by use of their stabliators. The B-52 doesn't roll in this manner and they do not have ailerons.

 

[Schnugg]

Schnuggapup-
What exactly is the difference between loss of lift via spoilers and that of ailerons on the downward moving wing? I suppose the issue would be the upward moving wing, seeing that with ailerons additional lift is generated. I was always under the assumption that any aircraft would require a power increase (given a centered ball, correct initial power input) with any roll. Am I wrong?

Some good explanations above as well. I'm no aero major, but the spoilers on an F-14 deploy up (a bit ~6 or 8 Degrees) all the time when DLC is on during a landing. You need to fly a bit faster (6 kts), but they allow you to use a vernier wheel on the stick to roll in lift as the spoilers settle down together or bump them up for a quick settle. Usually used in close to control a rising ball where a power reduction correction would be bad. Doen DLC works pretty good, up DLC is not to good.

The width of an F-14 also means if you start an AOB with spoilers and tails, you need to counter it, so we have a lot of loss of lift with the spoilers fluttering and the tails going. Hence the name the "turkey"...ever seen a real turkey fly? You nend rudder otherwise nose drift starts. Yaw SAS is critical in this airplane. The digital flight controls (DFC) of the upgraded f-14s really helps on the ball, not much nose wander and you can almost fly the ball feet on the deck.
All aircraft require some power with line up corrections, it's just it is more significant throttle movement in an F-14 than an F/A-18 for example.

Hope this convoluted kluged up answer helps.

r/
G

 

[A4sForever]

PICKLE, PAUSE, and PULL

What exactly is the difference between loss of lift via spoilers and that of ailerons on the downward moving wing?

The other answers were basically right on ... an addendum:

DIVE BOMBING: do we still do that? Are you SNA's TAUGHT HOW to do a dive bombing run or do they just teach you to "get ready for PGM's"? Is visual dive bombing still taught? One can only hope ... but if I had a choice, I would rather sit out @ 30-50 NM and kill the Sum'Beeyuch with a PGM. Who wouldn't?

In a dive bombing run, on a non-aileron wing, any corrections, however slight, kills some lift on the "downwind" wing, thus "dropping" the armament datum line (ADL) off (or south -- away) from the run-in line and target. Thus you must make a correction -- pull the pipper/ADL/gunsight --whatever you want to call it -- picture back to the target track and then roll wings level, re-acquire the correct sight picture/tracking path, and press on... you probably have to make several of these in the course of a run. No problem with POWER, as you are already pressing 500 KIAS with the throttles somewhere mid-range. With ailerons, you are just correcting about the longitudinal axis or, if you will, basically the ADL. Much easier, smaller, more controllable, precise corrections during the run.

So dive bombing: the difference with ailerons/other than ailerons?
In the A-6 with flapperons and inflight spoilers, my CEP's were 50-100' (and that's pretty darn good for A-6 visual dive, ask any A-6 driver or B/N. Heck, ask any A-7/A-4/F-4 driver). In the A-4 with ailerons, my CEP's were less than 50'. I even had a few training hops with a BULLSEYE CEP. Very good for me, very disturbing for a potential bad guy.

AT THE SHIP: It's kind of the same thing at the ship, although when you make flapperon/spoiler corrections for line-up, you will probably need a little power, as you are "killing" lift in the direction of the correction and you are not pointed downhill at 45+ degrees. But then in reality, you usually need power corrections at the ship in any aircraft with a line-up correction ... especially those corrections made in close-to-at the ramp.

ROGER BALL ......

 

[SteveG75]

I don't know why certain aircraft use spoilers exclusively in place of ailerons. I guess in the case of the F-14 the roll action is accomplished by use of their stabliators. The B-52 doesn't roll in this manner and they do not have ailerons.

One very simple reason, especially for the Grumman products. Flaperons (spoilers) allow the use of longer flaps that extend the whole length of the wing. Helps reduce landing speed at the boat.

If you look at a Hornet on approach, the ailerons droop to match the flaps basically increasing the flap area.

 

[PropStop]

One very simple reason, especially for the Grumman products. Flaperons (spoilers) allow the use of longer flaps that extend the whole length of the wing. Helps reduce landing speed at the boat.

If you look at a Hornet on approach, the ailerons droop to match the flaps basically increasing the flap area.

ah, that makes sense! thanks for the info!

 

[A4sForever]

Which came first: the chicken or the egg? The Flap or the Flaperon?

One very simple reason .... Flaperons (spoilers) allow the use of longer flaps that extend the whole length of the wing. Helps reduce landing speed at the boat.

STOP THE PRESSES!!!

Actually, that is not quite the case here. The original "A-6" Intruder, the Grumman A2F, had a large-area mid-mounted wing of moderate sweep --- 25 degrees at quarter-chord. The wing had trailing-edge flaps that extended over almost the entire length of the wing, so conventional ailerons were not fitted. Lateral controls was provided at low speeds by the movements of the flaps (operating as "flaperons") and at high speeds by a series of spoilers mounted on the upper wing surface. The spoilers could be operated differentially for roll control in flight.

THE ORIGINAL UGLY, the Grumman A2F INTRUDER

Check with your friendly local Grummie Tech-Reps --- I did. They tracked the answer down with HQ in LA --- whatever happened to Bethpage, anyway?? As an aside, one particular TechRep was a pilot RAG instructor of mine in winter '71-'72 !!! He lives !!! The experience didn't kill him !!!

According to the Bible of Grumman: the flaperon/spoiler configuration provided two (2) primary functions in the A2F design:

1. The system provided more positive roll-rate control @ high gross weights --- especially with heavy (i.e., 28 Mk.82's) external stores.
2. The dual control surfaces had the added bonus of providing a lift-killing device for the high-lift wing after landing; AFTER TOUCHDOWN and spoiler deployment.

Lowering the landing speeds was a by-product; but it was not in the design concept. (says Grumman)

Another little known item in the great old girl's development ...
During its design process, Grumman considered several different configurations, including a turboprop-powered (!!!) straight-winged aircraft (decidedly much too close to a P-3) with twin fins and rudders as well as a pure jet-powered aircraft with turbojets mounted in pods underneath M-shaped wings, with forward swept inboard panels and swept-back outward panels. The design that Grumman finally settled on (named Design 128Q --- by the company) was a two-seat jet-powered aircraft.

GRUMMAN ... God, I wish I had been born early enough to fly F6F's ........