CG computation F-14A/B

Hello all,

I apologize, because I know that this was discussed some time ago, but I can't seem to find it in a search.

I know our trim setting for cat shots is determined by our center of gravity. So I was curious, since I couldn't locate documentation detailing calculating this for the B, if I could find this for the older A model. Well.... I didn't, even after acquiring documentation with currency. So now, I'm wondering (and I know I don't need to, but it's the nerd inside of me) if our F-14 CG in fact changes or is even affected in game? Also, if it does, how did the pilots know their CG? I understand there is a basic CG for each individual airframe, but where's this data the details the arm of each individual station and computation for the balance of fuel? Also, if CG is part of DCS, then what would our jet's CG be? This part seems very vague still and I would like to know more.

Thanks to all for the help. I want to know, because I love this jet. It's a rock star compared to the others available. So much fun, and so much more to come!

Apparently CG calculations are done according to NAVAIR 01−1B−4, but I cannot find a copy online. I found an updated version that supercedes NAVAIR 01−1B−4, but it does not include the Tomcat. Oddly enough it includes the F-4.....kinda weird.

Apparently CG calculations are done according to NAVAIR 01−1B−4, but I cannot find a copy online. I found an updated version that supercedes NAVAIR 01−1B−4, but it does not include the Tomcat. Oddly enough it includes the F-4.....kinda weird.

Hmm...that is weird. What’s even more strange is the “A” performance tables don’t even specify where/how to determine CG. So it only deepens the mystery. I was hoping since it’s somewhat the same airframe with the station locations, that the arms can be at least determined from that, but alas nothing there. Yes the performance numbers will be off (different engines) but the center of gravity should be roughly the same.

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Just for reference, I found the NAVAIR 01-1B-4 comment on page 8-5 of NAVAIR 01−F14AAD−1.

Just for reference, I found the NAVAIR 01-1B-4 comment on page 8-5 of NAVAIR 01−F14AAD−1.

Yeah I see it too. Hmm... it’s such a mystery.

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Yeah I see it too. Hmm... it’s such a mystery.

 

 

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What's so mysterious about military docs not being avialable online for everyone?

I was hoping HB could provide something on that topic because they are ought to know the CG values for the various loadouts from their flightmodel.

CG computation F-14A/B

What's so mysterious about military docs not being avialable online for everyone?

 

I was hoping HB could provide something on that topic because they are ought to know the CG values for the various loadouts from their flightmodel.

It's not just the docs, its how and why they are split like this is the why we are puzzled. But, I'm guessing the book the NATOPs refers to may in fact be a reference for each tail number's operating CG, along with all the hardpoint CG locations and the example of how to calculate a flight's CG for takeoff. I what don't understand why the calculation portion was not included in the performance manual? Also, what happened to this document? Just something that may never get solved. Who knows, when the Navy got rid of them, the books probably got tossed as well. There would be no need for them to keep those records.

HB may not know. Because we don't even know if lateral CG is something that is simulated in the first place. If it isn't then there is nothing they would indicate nor provide on those values. It's pretty simple for ED to simulate the Hornet varying trim values for cat launches because its all predicated on weight. All they have to do is program the sim to react the way it should for such values without applying any effects of CG. If there was a way for use to put a 400lbs pilot versus a 150lbs pilot in the cockpit, then that would be a sure way of knowing. Or do a control of a vanilla jet as little fuel as possible. Then put two of the heaviest bombs on the furthest back of the same jet. Have them both launch with the same trim setting and compare? I'll try it.

Oh yeah, they are definitely simulating aft CG. Did two launches. One vanilla. One with two mk-84s on the rear. It immediately went into a 60-70 degree attitude leaving the deck. Try it.

Weight and balance data is unique to a specific airframe (although the variations should be very small), thats why its probably not included in the NATOPS, which is valid for all AC of a certain type.

Because we don't even know if lateral CG is something that is simulated in the first place.

The center of gravity is an essential parameter for flight mechanics calculations. There must be some CG value provided for the flight-model even if its static, which would mean that the effects of CG shift are not simulated. I highly doubt that however given the overall fidelity of the module and the time HB spent developing/tweaking the FM.

Then put two of the heaviest bombs on the furthest back of the same jet. Have them both launch with the same trim setting and compare? I'll try it.

Maybe testing in a less dynamic situation, i.e. level flight, would make the difference in trim required (if any) stand out more.

Here's a quick video I made. It's pretty clear and not only shows aft CG is simulated, but also forward CG. Pretty cool.

https://www.dropbox.com/s/lhpg6e2mpo433fi/CG%20test.mp4?dl=0

The next question is, would HB even know what the CG is? For all they know, it could be a bunch of variables with no concise reading. :dunno:

Apparently CG calculations are done according to NAVAIR 01−1B−4, but I cannot find a copy online. I found an updated version that supersedes NAVAIR 01−1B−4, but it does not include the Tomcat. Oddly enough it includes the F-4.....kinda weird.

Hey Nealius,

I found a 01-1B-40, and this manual simply is a weight and balance guide for dummies. Is this the manual you found?

Flipping through this it seems to be more of an example than anything pertaining to a particular airframe. It does say, "The aircraft manufacturer inserts all identifying data on the title page of this manual and on the various charts and forms. He completes all charts, including sample weight and balance clearance Form F, if applicable, at time of delivery. All subsequent changes in weight and balance shall be recorded by weight and balance technicians in accordance with instructions contained herein and NAVAIR 01-1B-50."

Unfortunately since this manual I found seems to be more of a guidance and not complete since it isn't aircraft specific, or missing actual data. I think these manuals were destroyed. Since the aircraft was taken out of service and some were sold to other countries.

Snickers.... I went through this during my DOD contract days.. look hard. It's there

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Snickers.... I went through this during my DOD contract days.. look hard. It's there

 

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Can you be more specific? This document, 01-1B-40 doesn't have the model or serial no filled.

No, that wasn't the one I found. I found the 01-1B-50, which I guess supercedes the -40 you found.

CG computation F-14A/B

No, that wasn't the one I found. I found the 01-1B-50, which I guess supercedes the -40 you found.

Okay. I don’t think it supersedes it. 01-1B-50 is for the weigh and balance control officers and how they maintain an accurate log of the aircraft basic operating weights and CG. 01-1B-40 is the document that comes with the airframe from the manufacturer. The one I have is just an example or blank because the title page has no model or serial number filled.

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Just to remind that CG is obviously calculated but more on the DCS side.

https://forums.eagle.ru/showpost.php?p=4104400&postcount=58

https://forums.eagle.ru/showpost.php?p=3984108&postcount=3

What exactly you want to find? Asking for military docs here is not a good idea.

Just to remind that CG is obviously calculated but more on the DCS side.

https://forums.eagle.ru/showpost.php?p=4104400&postcount=58

https://forums.eagle.ru/showpost.php?p=3984108&postcount=3

 

What exactly you want to find? Asking for military docs here is not a good idea.

Hey Draconus,

I’m not asking for docs. I’m seeking guidance on where to find what I’m seeking and collaborate with those who are also seeking what I am seeking which is the FS points for the weapons carriage. I know the jets CG varies from airframe to airframe. But the hardpoints shouldn’t, especially since the A/B is the same fuselage.

So are you saying CG is more something calculated passively with in DCS? If so, I do agree. Otherwise, we would be able to see the effects of loadouts/fuel burns and how the CG shifts fore and aft. What I would like to know is does it match with the real jet appropriately, if so will we be given a simplified graph from HB that will provide our CG for cat shots, if it doesn’t match then is there a way we can create our own graph to correspond with the sim? I know it’s not a highly sought feature, but this is just one that would make it stand out with the immersion even more. Maybe HB could make a kneeboard page that would mimic Form F with font that looks handwritten from the weight and balance officer?

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What I read is that you want devs to proove that they did correctly their job of simulation. Imho it doesn't work that way. You can clearly see the effects of CG changes in every aircraft both longitudinal and lateral. That's pretty foundational stuff in the FM. Or maybe you just seek some little info that's been asked before: how to set trim for take off with current loading?

What I read is that you want devs to proove that they did correctly their job of simulation. Imho it doesn't work that way. You can clearly see the effects of CG changes in every aircraft both longitudinal and lateral. That's pretty foundational stuff in the FM. Or maybe you just seek some little info that's been asked before: how to set trim for take off with current loading?

I can live with it “not working that way” if indeed that’s what DCS has done. But what myself and I think some others would like to see it work in a way that it does require us to have the jet correctly trimmed and notated as it should. Is that too hard to ask/desire? I don’t really think so. Especially if this developer can simulate a two person crew aircraft into one (with pretty darn good effect) then the ability for us to have a page in the kneeboard showing our weight/loadout/%MAC for takeoff would be doable. Better yet if I can just find the data I’m looking for myself, which you seem highly against, may just provide us our own of determining if CG is simulated like the real jet, and if it is we can use that and make our own calculation for takeoff CG. If it doesn’t match, then......oh well.

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I would also like to know the aircraft takeoff CG, even if just for the sake of a more complete preflight calculation. I wish HB would share something on this, as they must have some kind of knowledge. Empty aircraft CG would already help a lot...

I would also like to know the aircraft takeoff CG, even if just for the sake of a more complete preflight calculation. I wish HB would share something on this, as they must have some kind of knowledge. Empty aircraft CG would already help a lot...

Exactly. Me too. It adds more immersion. I think my idea is a pretty good one. It doesn’t necessarily have to be exactly like form F, which is what the pilots would get that shows the basic weight and CG, stores loaded their weight and moment CG deltas, fuel loaded and CG delta, and the grand total for takeoff weight and CG thus for trim position. That could all fit in a kneeboard page. Now, can it be done? I don’t know, that’s up to HB. Either way, if I can find what I am looking for.....that’s already half way, maybe more.

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I can live with it “not working that way” if indeed that’s what DCS has done. [...]

Better yet if I can just find the data I’m looking for myself, which you seem highly against...

I try to be as clear as possible but you misunderstood me second time. I said only that CG changes are simulated in DCS (and F-14) 100% and if you doubt this devs are not obligated to prove you wrong. It might not be applicable to HB as they are happy to brag about their simulation details :thumbup:

And I'm not against you finding the data. It was just notice to save you from trouble of breaking some forum rules.

I am interested in CG/%MAC data depending on fuel and stores too as this is not only useful for take off trim but rather crucial for flight safety to not lose control if stores are jettisioned in a wrong way or other situations which we are warned about in real manuals and there are many references to.

I try to be as clear as possible but you misunderstood me second time. I said only that CG changes are simulated in DCS (and F-14) 100% and if you doubt this devs are not obligated to prove you wrong. It might not be applicable to HB as they are happy to brag about their simulation details :thumbup:

 

And I'm not against you finding the data. It was just notice to save you from trouble of breaking some forum rules.

 

I am interested in CG/%MAC data depending on fuel and stores too as this is not only useful for take off trim but rather crucial for flight safety to not lose control if stores are jettisioned in a wrong way or other situations which we are warned about in real manuals and there are many references to.

Right, the CG is simulated. Clearly it is. The question is by how much in accuracy. But even if it’s not, we can still determine by how much and adjust. Anyways, I don’t doubt the programming capabilities. My next resource to look into is museums or archives to see if maybe they were able to get a hold of this for preservation. I did find a doc that has FS points but it doesn’t have them for weapons or fuel/wings. It does have the points for gear and various other things but I don’t think I can use that to determine CG from stores.

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If you can find empty aircraft CG, MAC length and MAC distance from the nose (or any other point), everything else can be calculated/approximated from that.

Am I crazy in thinking this data will be in the manual eventually? With an online manual you could even have a dynamic calculator; it’s been done before in FSX, if I remember right.