low priority Main Landing Gear Retraction Speed

[Stubbies2003]

I think you might have missed exactly what this thread is about. It's not about the gear's operating limits (VLO/VLE) but about it's animation.... how the gear looks as it retracts or extends.

 

This is a detail that would be completely transparent to you from inside the cockpit during a normal takeoff (I guess unless you're closely watching your wing man during such a critical phase of flight...formation takeoff?).

 

 

No I got the point. My point being that even if it wasn't just shown but also simulated this way for drag etc. that is the only possible effect that could even be worried about. Thus why worrying about the gear retraction is a rather silly point when there is so much more that this module doesn't even have yet.

[Deano87]

Dude, we don’t have Mavericks, harms, nav lights, collision lights , etc and you’re worried about gear speed ?

 

For the record I’m not “worried” about gear retraction, I’m just posting video material that supports what the OP said. Ideally this would be reported as an animation bug and get added to the bottom of the very long list of things to get done. I don’t believe anybody here is saying “DROP EVERYTHING, FIX THIS GEAR ANIMATION RIGHT NOW.” More like “Hey, thats needs looking at down the line, can you add it to the list please?”

[Northstar98]

Why argue? It's obvious.

 

Difficult to tell in that video, it looks pretty sticky at the time stamp but 50 seconds it looks much smoother, and doesn't appear to change speeds

[Frederf]

It's not difficult to tell at all. Raising the gear has that speed change. It's 3000 PSI hydraulics, it's not "sticky." The bounce in the struts you're seeing is just how powerful the change between the two speeds is. Look at any retraction video

It's the same every time.

 

Yeah, at :50 it looks smoother because that's gear extension which is not the same as retraction.

[Deano87]

Difficult to tell in that video, it looks pretty sticky at the time stamp but 50 seconds it looks much smoother, and doesn't appear to change speeds

 

It still changes speed at 50 seconds, harder to see because of the camera movement. But its still there.

[mvsgas]

I still don't get why people keep posting this video that serve no purpose. People want something change based on the way it looks, but they don't know what they are looking at.

 

- First, this is not a block 50, if you cant tell the difference, thanks for proving my point.

- Two, we do not know the condition of this landing gear. What do I mean? Why where they ops checking the landing gear? What is the reason the aircraft is on jacks and they are looking at the Nose Landing Gear (NLG)? The video description says:

my class and me swinging the F-16 Nose and Main Landing Gear

Do you know the aircraft we use for technical school?

 

- Third, what pressure is the hydraulic mule? Hydraulic mule is what is used to provide pressurizer hydraulic fluid to the aircraft during operational checks. One of the checks for the landing gear is to raise the LG handle, and increase hydraulic pressure slowly until the landing gear retracts, so is this at 3000 psi or 1500psi? How do we tell?

 

In sum up, this is not the F-16C in DCS, we do not know the condition of the landing gear and we do not know the hydraulic pressure, why even use an F-16 video? Might as well post a 747 landing gear retraction and used that as reference.

 

ED will choose how to model this, either way is fine to me. I just which people saying something is wrong would use technical information that is helpful. Like:"The retraction rate slows down when retract actuator get to "x" value because "Y" valve does this". Instead we keep seeing: "This is wrong because I said so".

[VampireNZ]

Just my 0.02c as a 25+ year aircraft tech, with all due respect to Mr. Mvsgas, it doesn't really matter what rig they are using, rig pressure etc etc - there is quite clearly a reduction in retraction rate of the F-16 main landing gear. This is VERY obvious! Couple more much clearer examples

 

 

 

Also some other info I found - There is a spec which says the gear and doors must be up and locked within seven seconds from raising the handle. To meet that spec, the main gear has to move so fast, it impacts the uplocks so hard it would soon suffer fatigue damage. So the gear moves at two rates, very fast over the first half of its travel upward, then much more slowly on up to the uplock. That way it can meet the spec, yet not damage the uplock.

 

The above can easily be confirmed by any Viper techs floating around - @Panther?

 

IMHO I would crap a square building product is the MLG smoked up into the bay at that initial retraction speed. In the second vid you can clearly see the little bounce as the gear hits the uplock even at the slower speed. Eventually the structure would have issues if it crashed into the uplock at full speed over and over and over again.

 

Does it need 'reviewing' - perhaps. Personally I can't see my own MLG, and am not looking at my wingmans MLG at takeoff so meh.

[Deano87]

ED will choose how to model this, either way is fine to me. I just which people saying something is wrong would use technical information that is helpful. Like:"The retraction rate slows down when retract actuator get to "x" value because "Y" valve does this". Instead we keep seeing: "This is wrong because I said so".

 

You need to be aware that people noticing this issue might not have the experiance with the aircraft that you do, the technical knowledge or the vocabulary to be able to explain what they are seeing, so are never going to satisfy your request for detailed proof.

 

Regardless, I found a Block 50 video exhibiting the same movement as ALL the rest of the F-16 retraction vids I've seen, which leads me to believe that the main gear retraction rate slowing at some point during the swing is indeed normal and should be replicated in the sim.

[VampireNZ]

Agree with Deano87 - I don't think we need to locate the exact microswitch on a specific MLG wiring diagram and the associated shuttle valves that direct fluid through specific flow restrictors (or whatever mechanism is used) to all agree that - yes the travel rate is indeed slowed for the second half of the retraction cycle.

 

Not that you could show that information on here anyway, and I guess while it would satisfy some peoples 'need for real proof' - it is not strictly necessary to reach a conclusion.

[=Panther=]

What everyone is pointing is how on the viper the gear rate slows at the end of the swing. What is happening in a nutshell is the geometry and ratio is changing from a fluid upswing to now an up and a rotation. There is no limit switch or slow down switch or any electrical component that causes it, it’s just the geometry and ratio of all the components changing in the last quarter.

[Deano87]

What everyone is pointing is how on the viper the gear rate slows at the end of the swing. What is happening in a nutshell is the geometry and ratio is changing from a fluid upswing to now an up and a rotation. There is no limit switch or slow down switch or any electrical component that causes it, it’s just the geometry and ratio of all the components changing in the last quarter.

 

Thanks for the info Panther!

[rrohde]

People want something change based on the way it looks, but they don't know what they are looking at.

 

Ain't that the truth...?

 

Well said for the rest of your post, too! :thumbup:

[NorgeNate]

I feel I may need to chime in here. First, this is not block specific. All F-16's do this. If I remember correctly there is a certain parameters in the maintenance manual that need to be met during an ops check. Upon selecting gear-up the gear and doors need to be up and locked within a certain amount of time. I want to say somewhere around 7 seconds or so. For this to take place the main gear needs to retract rather quickly (see above videos). To keep the main gear from slamming into the wheel well with too much force it is slowed down (again, see above videos) at a predetermined point by a metering valve. If it were to be allowed to fully retract at the initial speed there would be serious fatigue and wear on the up-lock hook assembly as well as the up-lock roller tabs which are incidentally part of the lower shock strut assembly and would be a huge PITA to change all the time due to cracks. The OP is right, it is slowed down. Do we need that modeled? Probably not. Would it be a nice attention to detail by ED if they implemented it? Yes it would. Cheers!

[FightsOn]

Now the F-16 is pretty far along in development.  Any way to get this animation looked at?