C-17 Globemaster III

[SoD Stitch]

I remember my professor actually teaching us about the catapult launch forces. For those who do not know, the airplane is attached to the shuttle with a known tensile strength length of stock metal. At the end of the shuttles run, the airplane momentum carries it past the shuttle c0ck. With a huge "bang", the metal connection is actually broken, or snapped in half. I know. I actually examined one as part of my engineering curriculum.

As I recall, there are all different sizes of the "hold-back" bolt, depending on the launch weight of the a/c.

And, actually, the bolt just holds the a/c back from the impetus of the catapult shuttle trying to launch the a/c; as soon as the "pull" from the catapult shuttle exceeds the design strength of the hold-back bolt, it snaps and releases the a/c for launch.

 

[Matt308]

Hi Matt,

>Assuming not, I am a bit incredulous that you would base a technical position on a game. I have better confidence in you than that, buddy.

How about you try and sum up my "technical position" so that I can tell you that you got me completely wrong in order to restore your confidence?

I won't even comment on the rest of your post because I see no connection to anything I wrote here.

Regards,

Henning (HoHun)

Henning this isn't personal, buddy. Please don't go there.

I am only carrying on a dialogue that became technical. I provided a technical explanation for my position. It wasn't meant as a personal attack.

I can't sum up your technical position. I have no idea what that is. You have only cited playing a game on a PC of which you have not indicated you have any contributions to the software application's origin. Do you have the high level software development requirements that model the aircraft carrier deck structural loads, the shuttle kinematics and the strength of materials used for the launch modeling? I think not. I can't believe that a PC game would contain such level of detail, as this would make the game so costly as to be virtually out of reach to anyone except gov't entities.

Settle down. This isn't a pissing match. All is well.

 

[Matt308]

As I recall, there are all different sizes of the "hold-back" bolt, depending on the launch weight of the a/c.

And, actually, the bolt just holds the a/c back from the impetus of the catapult shuttle trying to launch the a/c; as soon as the "pull" from the catapult shuttle exceeds the design strength of the hold-back bolt, it snaps and releases the a/c for launch.

You are right SoD. Here's a good explanation I found.

The purpose of the holdback is to keep the aircraft from moving forward
prior to the cat stroke. It holds back the AIRPLANE, not the shuttle. If you can find a detail photo of a carrier aircraft's nose gear, you will see, on the forward side, the nose tow or launch bar. I t is normally stowed in the 'up' position. Prior to launch, the bar is lowered. The transverse knob on the end of the launch bar engages with the notch at the front face of the shuttle.

In the good old days, the holdback was a machined bolt with a precisely
defined breaking strength. One end went into a socket in the aircraft
(various locations, usually in the fuselage), the other end went into a socket
on the holdback device, essentially a chain attached to the deck which
locked into a serrated track. These days, the hold back is a non-frangible
arrangement (broken pieces of holdback being a Not Good Thing on a
flight deck, not to mention one more thing to keep track of and replace). Of course, in the good old days, there was no nose tow, the shuttle was
attached to the aircraft via a cable bridle which connected to rearward
facing hooks in the main gear wells. The non-frangible holdback is
essentially a spring-loaded socket (aircraft side) and a knob-ended
deck-side fitting with which it engages.

Whichever the design, the intent of the holdback is to keep the aircraft
from moving out of engagement with the shuttle. It goes like this:

As the aircraft taxis into the cat, the deck crew attaches the holdback
and the nose tow engages the shuttle. The aircraft comes up against the
holdback (gently! gently!), and the cat operator tensions the cat to take
out the slack. If the shuttle gets a running start at your flying machine,
you'll likely lose the nosegear. At this point it is possible for the cat to
fire at any time (not on purpose, but it can happen) so the driver comes
off the brakes and goes to military power. There's a brief process
where the pilot checks for excuses not to do this again (particularly at
night), while the deck guys check for loose panels, leaks and such, and
the cat is fired. The cat pulls the aircraft out of the holdback and away
you go. Launch power varies with aircraft type and loading.

 

[SoD Stitch]

You are right SoD. Here's a good explanation I found.

The purpose of the holdback is to keep the aircraft from moving forward
prior to the cat stroke. It holds back the AIRPLANE, not the shuttle. If you can find a detail photo of a carrier aircraft's nose gear, you will see, on the forward side, the nose tow or launch bar. I t is normally stowed in the 'up' position. Prior to launch, the bar is lowered. The transverse knob on the end of the launch bar engages with the notch at the front face of the shuttle.

In the good old days, the holdback was a machined bolt with a precisely
defined breaking strength. One end went into a socket in the aircraft
(various locations, usually in the fuselage), the other end went into a socket
on the holdback device, essentially a chain attached to the deck which
locked into a serrated track. These days, the hold back is a non-frangible
arrangement (broken pieces of holdback being a Not Good Thing on a
flight deck, not to mention one more thing to keep track of and replace). Of course, in the good old days, there was no nose tow, the shuttle was
attached to the aircraft via a cable bridle which connected to rearward
facing hooks in the main gear wells. The non-frangible holdback is
essentially a spring-loaded socket (aircraft side) and a knob-ended
deck-side fitting with which it engages.

Whichever the design, the intent of the holdback is to keep the aircraft
from moving out of engagement with the shuttle. It goes like this:

As the aircraft taxis into the cat, the deck crew attaches the holdback
and the nose tow engages the shuttle. The aircraft comes up against the
holdback (gently! gently!), and the cat operator tensions the cat to take
out the slack. If the shuttle gets a running start at your flying machine,
you'll likely lose the nosegear. At this point it is possible for the cat to
fire at any time (not on purpose, but it can happen) so the driver comes
off the brakes and goes to military power. There's a brief process
where the pilot checks for excuses not to do this again (particularly at
night), while the deck guys check for loose panels, leaks and such, and
the cat is fired. The cat pulls the aircraft out of the holdback and away
you go. Launch power varies with aircraft type and loading.

Psych!

I "googled" the same on-line article you did; that's the best explanation I've seen, also. However, I understand the newer ones are reusable (don't know the details) so that the CV's don't have to stock tons (literally!) of hold-back bolts; not to mention having to pick up the broken pieces every time you have a cat launch (which could cause FOD if not picked up).

 

[Matt308]

Yeah that was a good explanation. Only thing lacking was diagrams!

 

[HoHun]

Hi Matt,

>I can't sum up your technical position. I have no idea what that is.

Exactly - I didn't express any You accidentally implied something, and I couldn't figure out what you implied accurately enough to point out that it was a misunderstanding.

So my request for a summary was not a rethorical one, and no sign that I was angry in any way ... your posts were clearly indicative of an innocent communication failure.

No hurt feelings here - in fact, I thought it was funny though I couldn't clear it up as quickly as I thought

>I can't believe that a PC game would contain such level of detail, as this would make the game so costly as to be virtually out of reach to anyone except gov't entities.

There is nothing that calculates loads in X-Plane, but Rigs-of-Rods features a universal finite element approach and should be advanced enough to simulate aircraft-carrier interactions qualitatively (for illustration purposes, at least). No doubt that one could never expect any kind of useful accuracy for engineering purposes from it, of course.

Regards,

Henning (HoHun)

 

[Waynos]

Sorry for this random question but, now that the RAF is buying its C-17's rather than leasing them, and adding more if the funds can be found, isn't it time we brought them into line with other RAF types and started calling them the 'Globemaster C.1' or similar? C-17A is absolutely fine, but its not very RAF is it.

 

[SoD Stitch]

Sorry for this random question but, now that the RAF is buying its C-17's rather than leasing them, and adding more if the funds can be found, isn't it time we brought them into line with other RAF types and started calling them the 'Globemaster C.1' or similar? C-17A is absolutely fine, but its not very RAF is it.

Supposedly, they are; from Wiki:

"In RAF service the C-17 has not been given an official designation (e.g. C-130J referred to as Hercules C4 or C5) due to its leased status, but is referred to simply as the C-17. Following the end of the lease period the four aircraft will assume an RAF designation, most likely "Globemaster C1"."

 

[Matt308]

Interesting. Didn't know that.