Bomb Toss observations

[-Ice]

After watching Wags' Bomb Toss video, I went out and spent an afternoon trying out some bomb tossing. I would like to share my observations in order to see if I'm doing it correctly or not, and if my observations are valid or not.

 

First of all, the experiment parameters - target is a T-72 tank on the X airfield north of Bantumi. This is an experiment so I did not want to have to search for targets and the abandoned airfield is excellent for this. I chose a tank because I did not want softer targets blowing up from a near-hit. I've tossed MK82s, MK84s, CBU97s, and CBU87s. This technique will probably work better with guided munitions but I am experimenting with this attack technique so I wanted dumb bombs to see where the bombs actually hit.

 

All my attack runs are made about 1000 AGL (or MSL, since I come in from the water), full throttle (about 300+ IAS), and pop up about 2nm from target. I've tried varying my climbs from 5, 10, 15, and 20 degrees. Please note the "nose up" and such is taken from the flight path marker and not the actual + symbol that denotes the gun cross. Also, pop up is done by pulling up until the FPM gets to the desired angle, and held there. This means that the bombs are released for a steady climb as much as possible, to limit factors that might induce error.

 

For comparison, on Wags' video, he attacked a group of soft targets (trucks) using a CBU87. Ingress was about 1500 AGL, 315+ IAS, pop up at 1.4nm. At bomb release, he was about 1700 AGL and pulling Gs throughout, approx 2Gs and 17 degrees up at bomb release, 1nm from target.

 

So, with that out of the way, on to my observations:

 

1. I have never gotten a hit with my MKs with a pop up release. If I pop up, stabilize to level flight, then release, chances of a hit increases, but for a "proper" toss, no.

 

2. Error increases as nose-up increases. 5 degrees is too shallow an angle for a "pop up," more like a peek up. 10-15 degrees give more or less the same amount of error, and 20 degrees nose up is even worse.

 

3. Chances for a hit is increased by both rippling bombs and off-setting the SPI by the amount of error noted for the planned attack angle. 2 MK82s on the standard ripple single settings, 10-15 degrees nose up, and point-locked SPI about 6-10 tank lengths before the target results in better chances of a hit. However, this relies a lot on guess-work and the off-set can be misleading based on angle and distance from target.

 

4. CBUs are the best weapon for this type of attack, as the bomblet scatter compensates for the errors. However, the CBU opens up close to the SPI so the scatter is greater behind the target (ie, the target will not be the center of the bomblet dispersal). Therefore, an off-set SPI to a few meters in front of the target may be desired to properly center the target when the bomblet disperses.

 

5. Standoff range is not greatly increased when using this technique compared to a standard, level-flight release. I estimate anywhere to 0.2-0.5nm difference compared to the standard release, but with live targets, sometimes that can make a difference as the pilot can slice away earlier. For example, on an ingress at 1000 AGL, 320 IAS, 10 degree climb 2nm from target, I can gain about 300-400 before the bomb goes off the rack at about 1.1nm. Therefore, bomb release is at 1300-1400 AGL. Doing a level-flight release at 1300 AGL, the bombs may come off at 1nm-0.9nm.

 

Conclusions:

This attack technique is only good if low-level ingress/egress to the target is a must. It trades accuracy for survivability, both from SAMs and from return fire from the target. While I can plant a MK82 on a tank's turret with a level-flight release, I'm happy if the same MK82 will get the tank with it's shockwave with a bomb toss. As far as standoff goes, the benefit it gives is minimal, but on a high-theat environment, that extra fraction might just mean missing the first stream of AAA. CBUs are the weapon-of-choice due to their dispersal pattern, although carpet-bombing MK82s can also be done (and would look cool too!).

 

I've done this experiment to see if I can bomb with "bullet" accuracy using a bomb toss technique. Apparently, the "shotgun" effect of a CBU is the only thing that will make this technique worthwhile. If the target area is so "hot" that you need to ingress at low level, you will not want to make multiple attack runs just to hit with standard LDGP bombs, better to toss a CBU in there and ge the hell out.

[robmlufc]

I thought when toss bombing you want to be increasing your climb angle as the bomb releases rather than at a steady angle, so you get the added effect of g force on the weapon to give you a bit more range? Good work though! I tried it earlier with 82s and they kept overshooting

[-Ice]

I keep my angle steady to limit the variables that can act on the munition. If we're missing targets on a steady climb, I seriously doubt a G-loaded release will improve things.

[Garfieldo]

I have been planning to conduct a similar experiment within the next days. Now, instead of starting from scratch I will be able to use your info as a starting position and hopefully be able to add something useful here.

 

Thanks for sharing!

[coolts]

Ice - try doing a constant 2g pullup as per the video. Thats the 'toss' part IIRC. That gives the projectile more force and therefore more velocity/range. The extra margin for error should be compensated by earlier release and allowing you to break off earlier.

[BiPod]

Nice effort and write-up Ice!

 

I will dispute the idea that you need to be pulling Gs to give the bomb extra toss. All that matters is the instantaneous velocity, including direction, that the bomb has on release. The fact that the bomb also has a centripetal force acting upon it becomes irrelevent the moment it separates from the aircraft.

 

AFAIK the reason you keep a constant G prior to release is just to help the computer maintain accuracy without wasting time and gaining altitude stabilising at zero before release.

 

You have inspired me to give this a go.

 

BiPod.

Edited April 2, 2011 by BiPod
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[Cibit]

Hey Ice was that you on the T&T server last night?

[WynnTTr]

Nice writeup Ice but I think as with everything in life, the more practice you get the better you'll get. Give it time and I reckon you'll be able to toss a Mk82 right onto the turret.

[coolts]

Nice effort and write-up Ice!

 

I will dispute the idea that you need to be pulling Gs to give the bomb extra toss. All that matters is the instantaneous velocity, including direction, that the bomb has on release. The fact that the bomb also has a centripetal force acting upon it becomes irrelevent the moment it separates from the aircraft.

 

AFAIK the reason you keep a constant G prior to release is just to help the computer maintain accuracy without wasting time and gaining altitude stabilising at zero before release.

 

You have inspired me to give this a go.

 

BiPod.

 

 

If there is no benefit on the weapon flight from maintaining g's in the pullup, there are still benefits to the attack profile as you can stay masked for longer rather than going into a steady climb earlier. The later you leave your pullup the less chance you have of taking fire

[SonofEil]

It trades accuracy for survivability

 

That's how it's always been advertised! It's a huge accuracy trade!

 

I repeatedly took out a fuel farm with a tossed CBU-97 from +/- 3nm without a problem. I'd dive to gain speed from about 7nm out, then pull up for the toss at about 3.5 out, 350kts. It never failed to level the place!

 

Trying to hit one tank with one tossed mk82 is an unrealistic expectation in the first place. At the same time, it's fantastic practice and allows you to clearly see the errors to improve accuracy.

[-Ice]

Coolts, I've tried both constant-G and stable-climb release, as I said before, the additional "range" it gives you is small. I'd be surprised if the technique gives you a 1nm range advantage over a level-flight release, more like 0.2-0.5nm, but in a live theatre, that just might save your life. Also, constant-G vs stable-climb release both give out the stated 0.2-0.5nm range advantage, give-or-take a few, so one isn't really "better" than the other... I noticed the error was slightly more with the constant-G release, but it's just a crater-length away so no big difference.

 

Bipod, your reasoning behind constant-G vs. stable-climb is noted and I do agree with your points. However, I am guessing with the low speed (300+IAS) and/or the low G (2G), the difference I've seen with a constant-G vs. stable-climb has not been great, ie just a crater-length. A significant difference would be maybe 3-4 tank lengths.

 

*** Please note that I am not good with distances so I estimate distance based on target. Crater-length in this case is the diameter of the crater made by a MK82 bomb, tank length would be the length of a T-72 tank.

 

Wynn, I agree that more practice = better but so far, I've tossed about 50+ MK82s and my error is more-or-less constant. What this means is that with all my variables constant (altitude, speed, pitch up, etc), the error is the same meaning the technique is good and the results I am getting is the best I can get. Better flying will only tighten up my error grouping, but the error will still be there.

 

quinn, I do agree that it trades accuracy for survivability, I was curious how much of a tradeoff that is. If I can pop tanks with MK82 from a level release and the only way to get a tank is with a CBU97 from a pop up release, at least I now know the limitations and can plan accordingly.

[BiPod]

Thanks for sharing your results with us. I guess the quote below is the crux.

 

quinn, I do agree that it trades accuracy for survivability, I was curious how much of a tradeoff that is. If I can pop tanks with MK82 from a level release and the only way to get a tank is with a CBU97 from a pop up release, at least I now know the limitations and can plan accordingly.

 

So now we have an idea of the inaccuracy, the next question (for me at least) is the one of survivability. If I'm in the mood tomorrow I may have a go at testing this, but with so many variables I doubt there will be a simple answer.

 

Given Ice's experience, I think level bombing at high altitude is a better option.

 

BiPod.

Edited April 2, 2011 by BiPod
Clarity

[Seanner]

I will dispute the idea that you need to be pulling Gs to give the bomb extra toss. All that matters is the instantaneous velocity, including direction, that the bomb has on release.

 

Technically since the CoG of the bomb is unlikely to be perfectly aligned with the CoG of the aircraft, the rotation of the aircraft would impart addtional "instantaneous" velocity...say the bomb is 1m forward and the aircraft is pitching 30 deg/s. The circumference of this rotation is 1m*2*pi ~ 6.3m, 6.3*30/360 ~ 0.5m/s.

 

Of course that extra half meter a second will make the bomb go probably a millimeter or so farther.

 

I'm saying all this so people don't get confused between the intuitive catapult effect of a rotation and the A-10's supposed physics-defying ability to NOT catapult anything...that's only because the bomb is not entirely coincidentally near the CoG of its launcher. If it was a bigger plane pitching faster and the bomb was attached to the nose, there would be a noticeable effect: 15m*2*pi * 60/360 ~16m/s. It still won't help the bomb go FARTHER because in order to get this extra velocity in the forward and/or upward directions, the plane would have to be diving (possibly inverted) just before release.. (edit: unless it had super awesome thrust vectoring and could spin in a circle while climbing at 45 degrees...the ultimate toss bombing or "discus bombing" plane).

 

Either way, the bomb WILL follow a different trajectory if the aircraft is pitching vs. flying steady, however small the difference is ;)

Edited April 2, 2011 by Seanner

[robmlufc]

Given Ice's experience, I think level bombing at high altitude is a better option.

 

BiPod.

 

Surely depends on the threat and terrain types though, a lot of the time its not ideal flying straight and level over the target! Popping up from under visual and radar and slicing back down after release has got to have its advantages. I know Tornados have toss bombed upto 4 miles range but they have an obvious speed advantage. Anything with GPS guidance has got to be a winner here, im off to give it a go! :)

Edited April 2, 2011 by robmlufc

[-Ice]

BiPod, I guess the best way to describe my experiment was to test out the accuracy of the technique. Now if the next question is survivability, that would now depend on a number of factors, the first of which is the type of threat you are coming up against.

 

In a modified training experiment, a couple of buddies and I used the same techniques and used CBU87s and 97s on the target. Targets consisted of 4 T-72s and a total of 8 BMP-2s nearby. Granted these are not "true" AAA threats, you will agree that loitering over them at 1000-2000 AGL is just asking for trouble. So, on to the observations:

 

1. Popup at 2nm was my standard, along with 10-15 nose up, steady climb, full throttle. If starting with 1000 AGL, and gaining about 400 feet, I get my bombs of just as the tanks start shooting. Now at ~1,500 AGL and slicing off target, the AAA fire has no chance. The important thing is to keep changing your plane of motion so that the AAA will always miss --- if you keep a level turn or not change angles for some time, a few rounds WILL hit.

 

2. Popup at 3nm was tried, and obviously the release altitude was much higher. I would say AAA fire starts more-or-less the same (forgive me if I don't notice a fraction of a second :D ), but with higher altitude, you have more time to get out.

 

3. Popup at 1.5nm was tried, and you're barely stable when the bombs come off. Altitude gain was about 150-200 feet and it was very important to slice as soon as you hear the clunk of weapons release. A few runs I came off clean, sometimes I get plinked with little-to-no damage. Still a clean run is far better than a close call.

 

 

So, what does this all mean? Distance from target on pop up exectuion will determine altitude at release and proximity to AAA threat. Is it better to pop up early and be higher? Is it better to pop up late and minimize "above the deck" exposure? It will all depend... on a) the immediate threat from the target and b) the threat from the theatre itself. After all, the assumption is that you are doing this technique because you need to be NOE flying to avoid a bigger problem (radar SAMs), so minimal exposure is desirable. However, exposing your belly at 2,000 AGL to a waiting Shilka 1.5nm away isn't good either.

 

Again, level-flight bombing is the better option for accuracy, high altitude level-flight bombing is the best in terms of accuracy and safety, but c'mon guys. This is DCS, not FSX ;) Sometimes we just need to get the adrenaline pumping and white-knuckle the joystick, y'know?

 

 

 

Seanner, thanks for the math on that. Again, stable-climb release done for consistency sake of the experiment, but further tests show that a G-loaded release doesn't make much difference anyway, whether a MK82 or a CBU87.

 

robmlufc, using LGMs or even IAMs puts the whole experiment out of whack. Accuracy alone will go up the roof --- a lofted MK82 or even a CBU87 releases under a 5mil tolerance. You can release a "smart bomb" under a 3/9, although with a low-altitude release, I wonder if it has enough time to correct if your release isn't too good. Point is, dumb bombs needs the greatest accuracy from the pilot in terms of targeting (having to offset the SPI) and flying, CBUs are more forgiving due to their "shotgun" nature, and "smart bombs" may be even more forgiving due to their self-guiding nature...

[Frostiken]

Sorry but, where can I find this 'bomb toss video' mentioned in the OP?

[bartleby]

Sorry but, where can I find this 'bomb toss video' mentioned in the OP?

 

[BiPod]

Nice work Seaner. I see from your post that the effect is greater than I thought it would be.

 

To translate this into distance: (using some very liberal assumptions)

 

 

 

From Wags video:

 

- 17 degrees pitch up (Taking 3.5 seconds to get from 1 to 15 degrees. Only 4 degrees per second!)

- 305 knots (assume IAS=true velocity)

- 2xg

- Flight time 11.6 seconds

- Flight distance approx 0.9 nautical miles (1,667meters)

 

Mixing with Seaners equation:

 

(1m*2*Pi)*(4/360)~0.07m/s

I don't have enough data to calculate the path of the Mk-82 so I will just use the horizontal velocity and assume that it does not increase.

Horizontal velocity at release = 0.07 x cos(17)

0.07 x cos(17) x 11.6 seconds gives ~78cm (<1 yard)

 

OR

 

Using Seaners more aggressive release at 30 degrees per second (higher G and lower speed)

0.5 x cos(17) x 11.6 = 5.5m

 

 

 

 

WAGS will have got an extra 78cm over 1,667 meters.

Seaners aggressive pilot will get 5.5m.

So releasing with the g load still on is more than I thought but still negligible.

 

...but I am now feeling like the weather man who has just given his report without first looking out the window. I'd better do some actual bombing now:music_whistling:

 

BiPod

Edited April 3, 2011 by BiPod
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