Calculating the distance a Bomb would travel.

[crewt 31]

1 minute ago, sarogahtyp said:

yeah. I did not check ur second measurement.

 

But what is that speed value about? is it just z-velocity or is it the magnitude of the speed vector?

No it's the magnitude, shit, should have thought about that earlier. I have to make a test applying G_force to the individual velocitys.

[Grumpy Old Man 3546]

Bombs don't have a max speed. They accelerate forever.

Drop one from 15k and monitor its speed.

Will reach about 1600km/h when dropped from 15km altitude.

 

Cheers

[sarogahtyp 1108]

1 minute ago, Grumpy Old Man said:

Bombs don't have a max speed. They accelerate forever.

Drop one from 15k and monitor its speed.

Will reach about 1600km/h when dropped from 15km altitude.

 

Cheers

wow.

[Grumpy Old Man 3546]

I'm sure if I track the current acceleration it will always stay the same once the glide angle is reached.

Dropped one from 50km alt, speed at impact was above 3300km/h with constant acceleration.

This is all kinds of weird, no idea if there's a formula for that, probably needs lots of fiddling.

 

Cheers

[sarogahtyp 1108]

14 minutes ago, crewt said:

No it's the magnitude, shit, should have thought about that earlier. I have to make a test applying G_force to the individual velocitys.

this is not the solution.

 

I think you have to do something like this per simulation cycle:

 

Apply G acceleration to z speed.

Apply deceleration by air friction to z-speed. (sideAirFriction)

apply deceleration  by airfriction to x-y-speed (x-y magnituide) (airFriction)

 

Edited May 10, 2017 by sarogahtyp

[Grumpy Old Man 3546]

I still think you can calculate the impact point from a droppoint, should be possible somehow.

Gonna give it a look.

 

Cheers

[sarogahtyp 1108]

2 minutes ago, Grumpy Old Man said:

I still think you can calculate the impact point from a droppoint, should be possible somehow.

Gonna give it a look.

 

Cheers

I tried that with bullets without considering g-force and I got a 4th degree equation. To solve that is beyond my math skills.

[crewt 31]

The major Problem for me is still the weight, can wrap my head around that one. If Bohemia is acc calculating the Bombs by the function t_d provided, they must have some kind of Weight/Mass, or the entire function is... useless. basicly. 

 

 

6 minutes ago, sarogahtyp said:

I think you have to do something like this per simulation cycle:

 

Apply G acceleration to z speed.

Apply deceleration by air friction to z-speed.

apply deceleration  by airfriction to x-y-speed (x-y magnituide)

 

Most likely relative to the vector of the Bomb?

[sarogahtyp 1108]

Just now, crewt said:

The major Problem for me is still the weight, can wrap my head around that one. If Bohemia is acc calculating the Bombs by the function t_d provided, they must have some kind of Weight/Mass, or the entire function is... useless. basicly. 

 

 

Most likely relative to the vector of the Bomb?

 

ammo are non physics objects without a mass in arma. This is a fact!

Therefore the thrust value (you dont need that here!) is the same as acceleration and therefore those airfriction is calculated without mass.

Accept this fact. There is no mass. So u dont need it.

[pierremgi 4897]

25 minutes ago, sarogahtyp said:

this is not the solution.

 

I think you have to do something like this per simulation cycle:

 

Apply G acceleration to z speed.

Apply deceleration by air friction to z-speed. (sideAirFriction)

apply deceleration  by airfriction to x-y-speed (x-y magnituide) (airFriction)

 

 

Just wondering if you're in a "framed" or "cycled" , so you're working on dt (differential time), not t (time).

So, why not use speed differences (dv) and apply a non-physic formula but a command, based on a test with https://community.bistudio.com/wiki/setVelocityTransformation 

Not tested yet. " It can be used as a position tracker with all necessary information collected, copied and then released within one function. "

[sarogahtyp 1108]

49 minutes ago, pierremgi said:

 

Just wondering if you're in a "framed" or "cycled" , so you're working on dt (differential time), not t (time).

So, why not use speed differences (dv) and apply a non-physic formula but a command, based on a test with https://community.bistudio.com/wiki/setVelocityTransformation 

Not tested yet. " It can be used as a position tracker with all necessary information collected, copied and then released within one function. "

 

if I understand that command correct then it can be used to interpolate a position and corresponding vectors between two objects.

How could this help to predict the touch down position of a bomb before (or just in the moment) you drop it?

[pierremgi 4897]

15 minutes ago, sarogahtyp said:

 

if I understand that command correct then it can be used to interpolate a position and corresponding vectors between two objects.

How could this help to predict the touch down position of a bomb before (or just in the moment) you drop it?

I can't test that right now (I'm on another script) but I imagined to register some free-fall trajectory, from high altitude (I guess there is no atmosphere variation in Arma) , with the ffur2007slx2_5 method (note). (data recovery)

In a second time, apply this bunch of data with the command, from anywhere, until the simulated projectile hits the ground. Not sure it works and in all cases (init speed, init pitch..) But if some constants could be extracted/identified then applied in this king of command, this could be fine to simulate the trajectory and obtain the hit point.

[crewt 31]

So -  Run your little code: 

Raw:

Spoiler

0    2063,6    12,3111    139    4,69953
0,505005    2.064    12    139    -3,42166
1,01703    2060,59    11    139    -8,38949
1,52399    2055,36    11    139    -11,9945
2,04004    2048,53    11    139    -14,3925
2,54199    2040,83    10,9926    139    -16,3049
3,05701    2031,95    11    139    -18,1987
3,56799    2022,15    11    139    -20,0832
4,06403    2011,74    11    140    -21,919
4,56    2.000    11    140    -23,7716
5,06201    1988,02    11    140    -25,6558
5,56201    1974,72    11    141    -27,5501
6,07202    1.960    11    141    -29,4713
6,56702    1945,08    11    142    -31,4129
7,08099    1928,46    11    142    -33,4121
7,578    1911,34    11    143    -35,373
8,07599    1893,25    11    144    -37,3541
8,56799    1874,38    11    144    -39,3363
9,06604    1.854    10,9267    145    -41,3607
9,56299    1833,23    11    145    -43,4138
10,059    1.811    11    146    -45,4799
10,554    1788,21    11    147    -47,5724
11,047    1764,23    11    148    -49,6848
11,553    1738,54    11    148    -51,8803
12,06    1711,74    11    149    -54,1063
12,568    1683,61    11    150    -56,3777
13,086    1653,83    11,3231    151    -58,7186
13,592    1623,56    11,3854    152    -61,0372
14,077    1.593    11    153    -63,2917
14,569    1561,69    12    154    -65,6118
15,057    1529,09    12    155    -67,9447
15,541    1495,62    11,6453    156    -70,2894
16,03    1460,77    11,7147    157    -72,6823
16,519    1424,54    12    158    -75,1207
17,013    1386,9    12    159    -77,6055
17,506    1347,95    11,9342    160    -80,1287
17,999    1307,83    12    161    -82,6804
18,489    1266,5    12    162    -85,2618
18,981    1224,18    12    163    -87,8591
19,473    1180,34    12    164    -90,5039
19,971    1134,6    12    165    -93,2175
20    1087,02    12    166,231    -95,993
20,972    1038,44    12    167    -98,7808
21    989,568    13    168    -101,54
21,95    939,24    13    170    -104,338
22    886,465    13    171    -107,227
23    832,24    13    172    -110,149
23    777    13    173    -113,088
24    721    13    174,208    -115,985
24    665    13    175    -118,909
25    606    13    176    -121,89
25    545    13    178    -124,971
26    482    13    179    -128,074
26    419    13    180    -131,155
27    354    14    181    -134,256
27    285    14    182,358    -137,504
28    216    14    184    -140,748
28,364    145,733    13,7834    184,713    -143,98
28,849    75,2335    13,8694    185,861    -147,184

Google Docs:

 

[sarogahtyp 1108]

okay I give up here. sorry.

As Grumpy said. It is very weird.

The acceleration is decreasing a while and then increasing for some reason.

I think it has to do with bombs up an dir vectors and the fins on bomb.

I am unable to extract anything useful from that data.

[crewt 31]

No need to be sorry, thank you for your help and very useful tips!

For the moment I still refuse to accept that I can't solve this. 

 

But hey, everyone knows that the bombs in Arma don't fly like in RL, (Btw.: maybe the jets Dlc  will make something about that.... ),  and this topic certainly gave me some strange WTF moments.

My next attempt will be to test the fall of the bomb, maybe BIS decided, that bombs really would adjust to glide angle after an certain amount of Time, that would be an usefull constant to work with, the Math from that point is pretty strait forward.

IF I find a solution I can life with, I will post it ASAP :P

[sarogahtyp 1108]

Could anyone post the following config entries for some bombs? I cant do that at work.

 

airFriction

sideAirFriction

coefGravity

 

Thx

[crewt 31]

Sorry, came home t late, a general sweet solution, config , if you are to lazy to open up arma or simply can't .

 

airFriction = -0.0005;

sideAirFriction = 0.1;

 

Even coefGravity isn't an config entry 

[Midnighters 152]

1 hour ago, crewt said:

Sorry, came home t late, a general sweet solution, config , if you are to lazy to open up arma or simply can't .

 

airFriction = -0.0005;

sideAirFriction = 0.1;

 

Even coefGravity isn't an config entry 

that's whack. "sideAirFriction" wtf?!?

[crewt 31]

From what I can tell it manages the alignment of the bomb, as well the stabilizing in flight direction.

 

At least according to the C++ code provided by t_d