Can you explain the different kinds of aircraft engines?

[Bjoern]

The F-14's were permitted minimum AB take-offs from shore stations, if really necessary, but not the ships, and no max AB take-offs from anywhere. If they had a flame-out during an AB cat shot, it would cause an un-recoverable yaw moment. Get that on a cat shot, it's all over. Probably all over the bow of the boat.
The engines, in AB, had enough power, far enough off to the side of the plane's centerline, that if one quit, but the second kept running, again, in AB, the plane would start to do a flat spin then and there, no matter how much rudder the pilot input. Grumman even stated the F-14 wouldn't do a flat spin, no matter what, at first. But after loosing a few to flat spins, they changed the NATOPS. No corrective action to a flat spin under any conditions, other than EJECT. Top Gun got that right in the movie anyway.
I can copy the entries from the NATOPS about all this...

The F-14 is a still a fun as heck plane to fly though! Especially if it's modeled with the TF-110 engines, as in the D model '14s. Better than 1:1 thrust to weight, which fighter pilots had been dreaming of since jets came about. Understandably!

Too lazy to dig up "Bye,bye baby!" and find out who to credit for the technique, but with enough altitude remaining, a flat spinning F-14 can be recovered by manually sweeping the wings to 68 degrees, thus moving the center of lift aft which will drop the nose. Not sure if this ever trickled down to the squadrons and if it saved some unfortunate butts, but at least the spin wasn't a guaranteed killer.

I'm not sure if it's unique to the RB.199 but there's also an arrangement where if electrical power is lost it goes to full throttle. Great if you're airborne and need engine power while you sort out the electrical gremlins, not so much if you're overly enthusiastic getting out of the aircraft at an airshow and get ahead of yourself during the shut down checks. Cue the entire crowd ignoring the flying display and looking towards the increasingly high pitched whine coming from the parking area followed by bits of engine being liberally spread across dispersal.
Took them a couple of weeks before it was ready to be flown out.

First time I've heard about that quirk. Neat!

 

[PhantomTweak]

Too lazy to dig up "Bye,bye baby!" and find out who to credit for the technique, but with enough altitude remaining, a flat spinning F-14 can be recovered by manually sweeping the wings to 68 degrees, thus moving the center of lift aft which will drop the nose. Not sure if this ever trickled down to the squadrons and if it saved some unfortunate butts, but at least the spin wasn't a guaranteed killer.

Thanks for the info, Bjorn!
Not that I'm an expert by any stretch, but I've never heard of that. I don't know how easy it would be though.
The pilot, who is the only one that has control of the wing-sweep, as far as I know, might have some trouble reaching the control. There is a fair amount of what they call "eye-balls out" force involved during a flat spin, and the pilot has it worse than the RIO, who is a lot closer to the center of rotation. It would tend to pin the pilot forward in the harness, arms against the cockpit side-walls, preventing him from reaching the controls, or either ejection handle. Unless he was fast and got things done before the spin developed very far. One of the few things about aircraft Top Gun got right.
Doesn't mean no one ever did it, just means the pilot would have to recognize the impending spin and react to it very quickly. As far as I know, though, the NATOPS just says FLAT SPIN--EJECT, in the Emergency Procedures section. No qualifiers, altitude limits, speed on entry, anything. Just jettison the aircraft. And if it has developed much past the beginning stages of a flat spin, the RIO is going to be doing the ejecting.
Fun times

Might be something interesting to try in Dino's F-14 in FSX...
Pat☺

 

[Bjoern]

Thanks for the info, Bjorn!
Not that I'm an expert by any stretch, but I've never heard of that. I don't know how easy it would be though.
The pilot, who is the only one that has control of the wing-sweep, as far as I know, might have some trouble reaching the control. There is a fair amount of what they call "eye-balls out" force involved during a flat spin, and the pilot has it worse than the RIO, who is a lot closer to the center of rotation. It would tend to pin the pilot forward in the harness, arms against the cockpit side-walls, preventing him from reaching the controls, or either ejection handle. Unless he was fast and got things done before the spin developed very far. One of the few things about aircraft Top Gun got right.
Doesn't mean no one ever did it, just means the pilot would have to recognize the impending spin and react to it very quickly. As far as I know, though, the NATOPS just says FLAT SPIN--EJECT, in the Emergency Procedures section. No qualifiers, altitude limits, speed on entry, anything. Just jettison the aircraft. And if it has developed much past the beginning stages of a flat spin, the RIO is going to be doing the ejecting.
Fun times

Dug through the book* again, but couldn't find anything. I swear I saw it in there, though.

However, and albeit copied from another website, this article explains it pretty well:
http://combatace.com/blog/5/entry-19-tomcat-spin-recovery/

Might be something interesting to try in Dino's F-14 in FSX...

I doubt it can be spun. Besides, being a "D" model, it doesn't have any reason to.

There are some videos for spin recovery techniques for the Aerosoft F-14A though.



*Not that it's a bad book. If you want to read a 200 page love letter to an aircraft, there's no way around it.
https://www.amazon.com/Grumman-F-14-Tomcat-Reminiscences-Service/dp/0760325766

 

[Victory103]

Beat me to it Bjoern, good post and answers the question. Also agree that Dino's "D" and all late model A/Bs had Digital FCS added, but you can spin the Aerosoft Cat model just fine.


For Pat, it's the B/D's with the GE F-110 motor that have the NATOPS warning about AB on take-off, the original and "not designed for the Tomcat" PW TF-30 allows AB take offs.

Guess no one wanted to take a stab a helicopter turboshaft engines?

 

[Bjoern]

Guess no one wanted to take a stab a helicopter turboshaft engines?

Turboprops with comparatively slow spinning propellers.

 

[SkippyBing]

Turboprops with comparatively slow spinning propellers.

Spot on. ~55,000 RPM down to ~360 RPM makes for a big gearbox!

 

[bbrz]

Spot on. ~55,000 RPM down to ~360 RPM makes for a big gearbox!

? which engine is that if I may ask?

 

[hairyspin]

A difference between helicopter turboshaft engines and many turboprop or turbofan engines is the turbine powering the helicopter rotors is often a free turbine. This means it's not mechanically connected to the gas turbine sections, it's instead driven only by the hot gas exiting the gas turbine. Watch a typical turboshaft-powered chopper from startup to lift-off and you'll hear the gas turbine start (accompanied by regular sparking sounds), run up to speed and sit there warming until the free turbine engages. The rapid speed-up of rotors to flying speed used to baffle me until it was explained.

 

[Mach3DS]

The same thing can be seen on an aircraft turboprop. If the exhaust pipes are at the front, it's typically an air coupled or free turbine. Meaning there is no mechanical linkage to the drive assembly other than exhaust gases. This is what is the primary reason for slow power conversion when running at Low rpm and then going quickly to high power....usually have to wait a few seconds for the air coupled to kick in.

 

[Bjoern]

These are a bit long, but seem to get the point between fixed and free power turbine along quite nicely.

https://www.youtube.com/watch?v=As-NZ5t8sxY

https://www.youtube.com/watch?v=8A2yr3ALt6c

 

[PhantomTweak]

However, and albeit copied from another website, this article explains it pretty well:
http://combatace.com/blog/5/entry-19...spin-recovery/

Great article! I stand corrected. I was only going by what I read in the NATOPS, NAVAIR 01−F14AAD−1, which is for the D model, the NATOPS POCKET CHECKLIST, NAVAIR 01-F14AAP-1B which is for the B model, and so on.
Apparently, the secret is out now! The Navy brass won't be happy, though. They published the NATOPS, and unless an "official" change is made, it's sacrosanct. Then again, Navy Brass has a "never-wrong" complex...
I am glad the info on how-to recover a flat spin got out, though. I hope it saved many lives, and planes. Even if it just saved 1 plane and crew, I'm all for it!
Thanks again for the info. Maybe never used in the Sim world, but it'd still be interesting to try!
Pat☺

 

[bbrz]

1.If the exhaust pipes are at the front, it's typically an air coupled or free turbine.
2.This is what is the primary reason for slow power conversion when running at Low rpm and then going quickly to high power....usually have to wait a few seconds for the air coupled to kick in.

1. Not really. The 'front' exhaust is there on e.g. the PT6 because it's a reverse flow engine. Has nothing to do with fixed or free turbine.
2. Flown both, fixed and free turbine turboprops but never noticed a significant lag (one of the main drawbacks in FSX/P3D turboprop engine simulation)

 

[Mach3DS]

1. Not really. The 'front' exhaust is there on e.g. the PT6 because it's a reverse flow engine. Has nothing to do with fixed or free turbine.
2. Flown both, fixed and free turbine turboprops but never noticed a significant lag (one of the main drawbacks in FSX/P3D turboprop engine simulation)

Yeah I meant pitch of the blade, not exhaust...oh well....too tired to care! lol. And it's not a set in stone thing...just a generality. Same with power. I've flown PT6, and yeah, it's not super noticeable there. But perhaps on heavier birds, with underpowered engines for the weight? Not sure. Just know that this is one of the reasons (excuses maybe?) for it.

 

[Bjoern]

Great article! I stand corrected. I was only going by what I read in the NATOPS, NAVAIR 01−F14AAD−1, which is for the D model, the NATOPS POCKET CHECKLIST, NAVAIR 01-F14AAP-1B which is for the B model, and so on.
Apparently, the secret is out now! The Navy brass won't be happy, though. They published the NATOPS, and unless an "official" change is made, it's sacrosanct. Then again, Navy Brass has a "never-wrong" complex...
I am glad the info on how-to recover a flat spin got out, though. I hope it saved many lives, and planes. Even if it just saved 1 plane and crew, I'm all for it!
Thanks again for the info. Maybe never used in the Sim world, but it'd still be interesting to try!

Well, to be fair, something that works for legends like "Hoser" Satrapa, won't necessarily work for Johnny McNuggetface, so the official line of punching out when in a spin is a more sensible solution than risking two funerals and a wrecked F-14.

 

[PhantomTweak]

Well, to be fair, something that works for legends like "Hoser" Satrapa, won't necessarily work for Johnny McNuggetface, so the official line of punching out when in a spin is a more sensible solution than risking two funerals and a wrecked F-14.

Very good point. A trained, very experienced Test Pilot will be able to accomplish a lot more in a stressful situation than Lt (JG) McNuggetface. Surprisingly, it costs a lot more to replace a pilot (and/or RIO) than a plane. Aside from the economics of it, there are the human considerations, families, relatives, and so on. The Navy would much rather their pilots and RIO's become members of the Martin-Baker club than a smoking hole. After all, that's what the seats are there for.

And now, back to your regularly scheduled engine discussion...

Pat☺

 

[Bjoern]

Surprisingly, it costs a lot more to replace a pilot (and/or RIO) than a plane.

Cue Army: "You are very much replacable, but this tank isn't."

 

[PhantomTweak]

Pshaw!
Any farmboy that's seen a tractor can drive a tank.
Of course, apparently most anyone can drive a fighter like the F-14, if our great sim-world is any indication.

I do think is takes a little more money to run a guy through flight-school than tanker school, but I've been wrong before. Many, many times...
Of course, what Drill Sergeants SAY and what's true are often two different animals.

Have fun all!
Pat☺