Aces High Bulletin Board
General Forums => Aces High General Discussion => Topic started by: jollyFE on January 22, 2008, 07:13:38 PM
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Here's a question for all you 11lb brains out there. If a bomb needs to travel 1000 feet to arm up, one would think that you would need to be at least 1k above the target. Does airspeed effect the distance which the bomb travels? Can I drop a bit lower if I am going fast enough so the bomb will travel 1k feet? If so is there a quick estimation of airspeed vs altitude?
thanks
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When I am bombing in my 234 I usually drop at 600. I think speed does play a role in the bomb arming.
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I think as long as the bomb travels 1000ft through the air then it will blow when it hits the ground. So, yes, you can drop at lower alt if you're going faster.
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Bombs do travel further in the horizontal, the faster your plane is travelling. You can even toss bombs by flying at high speed and releasing them while in a slight climb. I'm not aware of any tables calculating this, but it could be done. The formulas aren't terribly complex, but I can't remember what they are for the life of me.
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I've released 500lb bombs off of an A-20 from less than 100 feet AGL before, and had them detonate. I was doing in excess of 250mph IAS, pitched back about 10 degrees and lofted them in.
You may be able to find some of the loft bombing formulas on the web. Its pretty much a simple ballistics exercise (geometry).
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Originally posted by SpikesX
When I am bombing in my 234 I usually drop at 600. I think speed does play a role in the bomb arming.
As in the case above isn't that altitude shown in yards not feet so therefore making it well above the 1000ft needed to arm ?
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Originally posted by Stoney74
Its pretty much a simple ballistics exercise (geometry).
indeed, but nobody has posted the math yet :)
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Originally posted by xbrit
As in the case above isn't that altitude shown in yards not feet so therefore making it well above the 1000ft needed to arm ?
Yes, I usually go in a shallow dive.
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Yes speed makes a difference. And Yes angle makes a difference.
Diving in at a perfect 90 degrees you'll have to drop higher than you would dropping in at 45 or less. Bomb doesn't care what its orrientation is. As long as it has the time/distance from drop to impact to arm.
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thats pretty much what I though. Was looking for some rough estimate formula...perhaps I will try it off line for a bit and see what I can come up with. I think acft type shouldn't be anissue...only speed and alt.
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Airspeed does affect it and is the primary component of the distance required to arm the bomb.
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Reminds me, is there some way to turn the crosshairs on in offline mode? That would be the simplest way to see how much of an effect speed and angle have on jabo runs, but I haven't seen a setting for it. Is it only available in the TA?
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You'd need some basic calculus to determine the precise distance traveled based upon the initial speed, altitude and angle of release in conjunction with gravitational acceleration - a bit complicated although probably simpler than it would actually be in real life since I don't *believe* (I could be wrong) that air friction against the bomb is modeled in the game, which would introduce terminal velocity as a factor. ( I believe this because your bombs dropped from any altitude always seem to travel exactly the same distance as you do, such that you are always directly over the bomb strike when it strikes. In reality, they should fall farther behind as they lose the forward momentum.)
However, a quick and dirty calculation is easy - a very rudimentary approximation can be simply done from the pure dive angle using the formula minimum altitude = 1000*sin(dive angle) - especially as dive angles tend to be fairly steep. A more precise approximation would be to resolve the velocity at the time of release into it's forward and downward components, and use the classic distance/time/acceleration formula s = ut + 1/2*a*(t)2 to determine time to impact, and then solve for the the distance traveled along both vectors between the initial release and the impact.
Someone who still remembers how to do calculus would have to give you the precise formula to account for the parabolic path, however, if you wanted "exactly exact".
Given that you don't know precisely your angle and only your approximate speed and altitude and only the approximate altitude of the target I'd say that the quick and dirty simple formula - i.e. at a 45 angle a release at 707 feet would cause the bomb to travel the requisite 1000 ft in order to arm, and at a 60' angle, 866 feet is required, etc. is more than sufficient.
Although if you can judge your angle of approach, the altitude of your target, and keep track of your altitude precisely enough to actually take advantage of knowing that the minimum altitude to release in a 60 degree dive is 866 ft not 1000 (or about 0.4 seconds at 250 mph, and you're likely going faster) and still drop on the target and not hit the ground along with your bomb, you're better than me...
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Originally posted by hubsonfire
Reminds me, is there some way to turn the crosshairs on in offline mode? That would be the simplest way to see how much of an effect speed and angle have on jabo runs, but I haven't seen a setting for it. Is it only available in the TA?
I believe its in Arena options-->Flight mode flags->somewhere in there :confused:
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You asked.
http://www.math.uiowa.edu/~stroyan/CTLC3rdEd/ProjectsOldCD/estroyan/cd/45/index.htm
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Originally posted by Wes14
I believe its in Arena options-->Flight mode flags->somewhere in there :confused:
Indeed it is. I had looked through the Arena Settings, but didn't realize there were separate menus for all of those. I was right clicking them, not double clicking. Oops.
Who needs math when you can watch the impact point move around in real time? :)
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Originally posted by hubsonfire
I was right clicking them, not double clicking. Oops.
Well no wonder :p
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Actually, (cue in british accent) "its a simple matter of weight ratio. A 5-ounce bird could not carry a 1 pound coconut. That's my point." Plus you would have to know the "average air speed velocity of an unladen swallow." :D
All joking aside.... there are a number of variables that have to be assumed in order to answer your question. First off, as I post my non-math major answer we will have to assume that AH does NOT factor in air friction, and does NOT determine/factor terminal velocity. We also have to assume you are talking about level bombing where you have no vertical(either up or down) speed. But, if one assumes those factors then determining how far the bomb will travel is a matter of plugging in your altitude into a height-time formula to determine how low the bomb will remain in the air, then multiplying that time with your forward airspeed.
First you must determine how long it will take for the object (bomb) to drop from your altitude to reach the ground. That is expressed as:
Height=1/2(acceleration)*time^2 (where acceleration =32.15ft/sec/sec)
for example if you were flying straight and level at 1000ft, it would take the bomb 7.88 seconds to reach the ground.
Now assume you are traveling forward at 250mph.
Convert speed to feet/sec then mulitply that times the time the object(bomb) was in the air. That will give the total forward distance travelled. In this case a speed of 250mph equates to 366.67 ft/sec
So, the bomb is traveling at 366.67 ft/sec for a total of 7.88 secs. That equates to 2889.36 feet.
In other words even though you are only 1000 feet up, the bomb still travelled almost 2900 feet before it hit the ground. Plenty of time to arm.
You can play with the formulas to get an estimate of the bomb travel distances for each given speed. So, yes, I assume also that you could be significantly lower than 1K and still have time to arm your bombs.
NOTE: This of course does not reflect any downward angle. This distance formula only works based on flat level bombing.
ALSO Note: I was not a math major. If I am wrong, please disregard and drag me out behind the barn and shoot me.:D
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Solar, that just made my small brain hurt. Thanks to everyone who has responed so far ( I feel very stupid...lol).
I have been screwing around in offline and have gotten the bombs to go off when released between 600-700 ft with my airspeed a little over 250ish. I am still working the timing thing to become more accurate.
I will let you guys know.
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Solar10's linked page solves a different problem - the assumption is a bomb release from level flight. Solving for a divebombing drop - where you have both a forward and downward velocity, adds complexity.
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Now if only someone brought the yards into this discussion :)
It would be relevant at least when bombing the GVs, since the distance is shown in yards, right?
A bit over 300 yards, right? So if one drops while distance shows 400, it should still work?
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Yes, it should, although I'm not sure at what distance the icon distance changes from 400 to 200.
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The bomb will accelerate downward at 32'/sec/sec until it reaches termnal velocity which is primarily a function of mass and drag coefficiet (object shape and air viscosity) while it's forward momentum will remain relatively unchanged (slowed only slightly by drag).
To have a "chart", one would have to know the object weight, it's drag coeeficient, the air viscosity at varying levels from drop to target, it's initial forward and downward speeds and, I'm sure, a few other factors I've forgotten.
Suffice to say forward momentum lowers the effective drop altitude needed to arm the bomb.
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I remember reading somewhere that 190 pilots would fly at 500ft at about ~300mph at level flight and as the tank went out of sight under the nose they would drop their egg. I tried this only once and I got a kill with it.
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Originally posted by Solar10
I remember reading somewhere that 190 pilots would fly at 500ft at about ~300mph at level flight and as the tank went out of sight under the nose they would drop their egg. I tried this only once and I got a kill with it.
That was done but like anything else... timing is of the essence.