fixed The sabre is around 741lbs underweight as modeled.

[Tim_Fragmagnet]

EDIT: The F-86F-25-40 Standard aircraft characteristics document lists an empty weight of 11125 and a basic weight of 11585, a difference of exactly 460lbs, exactly as calculated in this thread once the ammo discrepancy and pilot are taken out of the equation.


EDIT: The sabre's ammunition weight is too low not because the wrong round's weight is modeled, but because a lower number of rounds are modeled. Each gun has 267 rounds instead of the intended 300.
They are firing M2 API and M20 APIT, at 1 APIT to 6 API for these rounds, + the weight of the links, the total weight should come out to 530.628lbs.
I will leave the original text of the OP unaltered.



As per the weight listings in the sabre flight manual, sabres of the F-25 and later variants have a gross weight of around 15,175lbs. Gross weight is stated as being a full load of machine gun ammo and fuel, on top of a 230lb pilot.

Those parameters in DCS bring the ingame sabre to a weight of 14,434lbs

Where is the weight loss
it's not fuel as that is accurate to the pound.
Ammunition weight is supposed to be around 518-534lbs so there's part of the missing weight.
Also the empty weight as listed is supposedly correct.

But there's the issue.

The empty weight of the sabre does not include the weight of the six AN/M3 .50caliber machine guns in the nose.

The empty weight of the real sabre is 11,125lbs WITHOUT the guns.

But lets break down the ammo weight first
in DCS 100% machine gun ammo is listed as 483lbs, not sure where this number comes from
That is, unless the only rounds we're firing are armor piercing incendiary, which they aren't since we have a ton of tracers.

CARTRIDGE, armor-piercing-incendiary, cal. .50, T49
0.23lbs per round
1800 rounds
414lbs, but that's not all, 
the links between the rounds are 0.038lbs each and there are 1806 of them
another 68.628lbs
bringing the ammo weight to 482.628
then the UI rounds it to 483.

This is wrong, as we are clearly firing tracers, which at minimum are 0.24lbs per round if they're also armor-piercing and incendiary, which would bring the weight to 500.628lbs.

However lets assume it's simple
In game the sabre appears to fire 1 tracer after 5 non tracers, so 1 tracer every 6th round

lets simplify it to the calculation of bullets alone for 1 gun and make the rounds simple tracer and ball/AP as ball/AP are both the same weight
300 rounds
50 are tracers, 0.25lbs per round = 12.5lbs
250 are ball/AP, 0.26lbs per round = 65lbs 
combined that's 77.5lbs
for all 1800 rounds that's 465lbs
Including the 68.628lbs from the 1806links
that's 533.628lbs thus 51lbs more than our current in game listing of 483 (482.628)lbs

there is 51 of the 741 missing pounds
690lbs left

What is included in the gross weight of the aircraft?

lets take a look

"Approximate gross weights include pilot (230 pounds), full internal fuel (JP-4), and 1800 rounds of ammunition.

so 690lbs left, lets take 230lbs away to account for the pilot
460lbs left, where is it. It's not the fuel, the fuel is accurate to the pound.

It's the guns

null

 

64.5lbs for the gun without the recoil adapter assembly and presumably without the barrel as well
4.5lbs for the recoil adapter assembly
10.91lbs for the barrel

75.41lbs per gun without the recoil adapter, or 452.46lbs for 6 guns,  7.54lbs under our remaining weight
79.91lbs per gun with the recoil adapter, or 479.46lbs for 6 guns, 19.46lbs over our remaining weight

I'm not sure what the recoil adapter actually is so, lets assume it's used, now lets assume instead of ball/ap, the non tracer rounds are actually API, which weigh 0.01lbs less per round, IE 15lbs less for 1500 rounds
we are now only 4.46lbs overweight
But, what if the tracers are actually armor-piercing-incendiary-tracers, which also weigh 0.01lbs less per round, IE 3lbs less for 300 rounds

We are now only 1.46lbs overweight

Seems "approximate" enough to me

Solution, increase empty weight by 479.46lbs and another 230lbs if the pilot weight isn't modeled after the fact, and then increase the ammunition weight to a rate that coincides with the type and amount of rounds being used in the belts.

Edited September 10, 2022 by Tim_Fragmagnet

[Flappie]

Excellent research work! I'll ask devs to investigate.

[=475FG= Dawger]

Without a proper empty weight tabulation, this is speculation.

The precise condition of the aircraft when it is weighed to determine its empty weight is critical.

Gross weights are approximate because each serial number has its own specific empty weight from which you calculate actual flight weights.

 

Edited July 10, 2022 by =475FG= Dawger

[Tim_Fragmagnet]

Speculation, maybe, but it is educated speculation, the sabre would not be the first aircraft made by the united states that would have its empty weight measured without fixed weaponry installed. WW2 fighters being a prime example.

Nor would it be the last. Go look up the A-7 Corsair II, you'll find both empty weight and basic weight. Guess which one has the cannon installed.

The US has a term called "basic weight" If the guns are installed, it's in the territory of basic weight, not empty weight.

As per NAVAIR 01-1B-50 as of 2015

As per TM 55-1500-342-23 as of 1986

Unless you're talking about a plane where it is not included in basic weight and is actually included in operating weight.

As per NAVAIR 01-1B-50 as of 2015

In both cases, guns are not included in the empty weight.
 

Yes, gross weights are approximate because different planes weigh different amounts, but being 741lbs off is not even close to approximate, 511 if you subtract the pilot if dcs models the pilot weight after the fact.

I doubt that the corrected weight of the ammo and the weight of the guns being almost exactly the correct approximate gross weight difference is a coincidence.

Edited July 10, 2022 by Tim_Fragmagnet

[=475FG= Dawger]

55 minutes ago, Tim_Fragmagnet said:

Speculation, maybe, but it is educated speculation, the sabre would not be the first aircraft made by the united states that would have its empty weight measured without fixed weaponry installed. WW2 fighters being a prime example.

Nor would it be the last. Go look up the A-7 Corsair II, you'll find both empty weight and basic weight. Guess which one has the cannon installed.

The US has a term called "basic weight" If the guns are installed, it's in the territory of basic weight, not empty weight.

As per NAVAIR 01-1B-50 as of 2015

As per TM 55-1500-342-23 as of 1986

Unless you're talking about a plane where it is not included in basic weight and is actually included in operating weight.

As per NAVAIR 01-1B-50 as of 2015

In both cases, guns are not included in the empty weight.
 

Yes, gross weights are approximate because different planes weigh different amounts, but being 741lbs off is not even close to approximate, 511 if you subtract the pilot if dcs models the pilot weight after the fact.

I doubt that the corrected weight of the ammo and the weight of the guns being almost exactly the correct approximate gross weight difference is a coincidence.

 

You are using 2015 standards for a 1950's aircraft.

Its unlikely the aircraft was weighed without its guns. However, the only way to know that for sure is to see the TO1-1B-40 for the serial number modeled.

Thus, it is speculative.

[Tim_Fragmagnet]

12 minutes ago, =475FG= Dawger said:

You are using 2015 standards for a 1950's aircraft.

Its unlikely the aircraft was weighed without its guns. However, the only way to know that for sure is to see the TO1-1B-40 for the serial number modeled.

Thus, it is speculative.

 

I also included the 1986 definition.
From 1986 to 2015, and there's actually a 2019 version of 01-1B-50 now that says the same thing, and since it has not been changed, it is still the same to this day.
For 36 years the definition for basic weight has included guns, therefore excluding guns from empty weight.

That sets a precedent. You can't tell me it wasn't like that for another 36 years or more before that, you have to prove it. ESPECIALLY since American WW2 fighter aircraft had their empty weight measured without their guns as well.

 

12 minutes ago, =475FG= Dawger said:

Its unlikely the aircraft was weighed without its guns.

That is speculation. Prove it.

 

I have provided plenty of evidence that shows that it is extremely likely that the sabre's empty weight was measured without the guns installed.

[=475FG= Dawger]

The confusion seems to lie in the definition of empty and basic weight. And I admit to contributing to that a bit.

Empty weight is truly empty and is really only used in an engineering sense.

The aircraft is weighed in the condition it will be most of the time with unusable fuel, engine oil, oxygen and all non-mission specific equipment. This is Basic weight but is generally referred to as the empty weight by pilots.

However, no matter what we call it, the starting weight prior to adding fuel, ammunition, pilot and mission specific items includes unusable fuel, oil, oxygen and the guns as they are non-mission specific equipment.

Is this starting weight accurate for the serial number in DCS? It clearly includes unusable fuel so one would assume it also includes oil, oxygen and guns.

Maybe, maybe not. However, one cannot know without seeing the relevant documents for the serial number in question.

 

Edited July 10, 2022 by =475FG= Dawger

[gnomechild]

What's a more likely scenario:

A: The devs misinterpreted the empty weight value in the manual since the convention of empty weight not including guns is not standard practice in flight manuals for many other countries. The missing weight in game would then almost perfectly accounted for by the weight of 6 AN/M3s + oil / fluids. 

 

B: The Sabre we have in game is modelled off a specific serial number with associated documents that show it's particular weight to be 700lbs less than other Sabres.

[=475FG= Dawger]

52 minutes ago, gnomechild said:

What's a more likely scenario:

A: The devs misinterpreted the empty weight value in the manual since the convention of empty weight not including guns is not standard practice in flight manuals for many other countries. The missing weight in game would then almost perfectly accounted for by the weight of 6 AN/M3s + oil / fluids. 

 

B: The Sabre we have in game is modelled off a specific serial number with associated documents that show it's particular weight to be 700lbs less than other Sabres.

A third choice is a combination of both of the above with some other errors thrown in.

It matters because adding 480 lbs to the nose will have a pretty serious impact on the flying characteristics. 

[Tim_Fragmagnet]

 

 

 

Here is documentation showing WW2 planes not having guns included in their "tare" (bare/empty) weight.

 

You're also confusing empty weight with weight empty

 

___

___

Welcome to American terminology, it's fun here.

 

So what's more likely

Between WW2 and 1986, the system and definition of measurements was changed, only to be changed back, and we just so happen to have a sabre that is 700lbs too light somehow?


Or the sabre is weighed empty without guns.


Even if you disagree with the gun weight, you must agree that the ammo weight is undeniably wrong from the provided ammunition data.

Edited July 10, 2022 by Tim_Fragmagnet

[=RS= Hart]

On 7/10/2022 at 8:27 AM, Flappie said:

Excellent research work! I'll ask devs to investigate.

If I'm reading the charts correctly and looking at the current weight of the F-86 in game the "basic weight" (as per the above definition which is full ammo, [no pilot assuming 230lb pilot as per Pilot manual referenced above in T.O.F-86F-1] is 11585lbs) is still set too low somehow at 11669lbs (assuming pilot weight removed this rounds down to 11,439lbs) which is still 149lbs under weight.

"Basic weight" conditions in mission editor vs Gross weight conditions as per mission editor

 

As a side note, the max internal fuel appears to be off by 16lbs according to the "Standard Aircraft Characteristics" chart for an F-86F-25 through F-40 "air superiority mission" typical mission graph and thankfully only 1lb off according to the T.O.F-86F-1 pilot manual.

 

Here's hoping that the weight issue is sorted out soon 

On a side note, given that this post from May 2022 states the guns are modelled at only half their weight in the code and the only updates the Sabre has received in the last 2 years have been to the controls effectiveness/IR signature/clickable switches and campaign missions, I wonder how it would affect the overall weight taking that into account?

 

[razo+r]

9 hours ago, =RS= Hart said:

[...]

On a side note, given that this post from May 2022 states the guns are modelled at only half their weight in the code and the only updates the Sabre has received in the last 2 years have been to the controls effectiveness/IR signature/clickable switches and campaign missions, I wonder how it would affect the overall weight taking that into account?

[...]

 

Just a FYI, ED has updated the ammo capacity in the January patch. So there is hope that they will eventually, perhaps even in this decade, correct the remaining issues.

Edited March 14, 2023 by razo+r

[Flappie]

@Tim_Fragmagnet I forgot to mention is was fixed with the introduction of DCS 2.9.

[Smyth]

Can someone from ED please clarify what source the new weight is based on? A clean Sabre in-game is now 15677lb gwt with full fuel and ammo. This is 500lb more than cited in various public-domain sources shown here and elsewhere.

[Flappie]

Then there's an issue in your DCS.

[Volator]

Yes, mine shows 15179lbs in MP (probably 2lbs worth of paint?!) with 100% fuel and 100% guns, so it fits the Dash-1 value for the -F-25 and later as it should.

Edited December 2, 2023 by Volator

[Smyth]

5 hours ago, Flappie said:

Then there's an issue in your DCS.

Apparently so. Now after re-launching DCS and changing nothing else the empty and full weights are correct.

Sorry for the false alarm - it looks like the game is playing me now and not the other way around.