F5E-3 Release Tables(manual) vs Real Life Planning

[Thisdale]

Greets everyone,

 

I was wondering if perhaps someone on here has experience with the F5E, or knows someone (you know...), that could comment a little on the planning phase of a CAS mission.

 

In more details, here's what i'm having problems with. Simple mission, go drop bombs on ground. In this example, i'm practicing my MK82SE drops.

 

Referencing to the Release Tables, i pick something to practice.

 

0 Angle (level flight release)

400ft above target

400nm

172 mils on sight

 

So, from this, i know that at moment of release, when my pipper is where i want it, i pickle at 400ft, at 400nm, while in level flight.

 

All good. And it works!

 

Now, shy of having a JTAC on site and no "F10" handy, the only way to know for sure about the altitude at ground level, is to have walked it, or have a very accurate map, of the exact point you are looking for.

 

Without the proper altitude information, i find the F5 to be increadibly innacurate (with all bombs, not juste the SE).

 

The big question regarding this post; how did the guys who flew that bird, accomodate, and adjusted for it?

 

Even with a good mission brief.. was there accurate data?

 

Your target is at 1854 feet

 

Or did they look at the map and eyeball around 1850 'cause on the map it says 1832 about 200 feet next to it?

 

Such as this:

 

What are/were the good tricks of the trade to properly evaluate a target under combat situation (not practice, F10 and Retries...).

 

Just as in example, here's my quick editor setup to test things out(below).

 

From the starting position at the top, which has a ground level of 131feet, all the way "down" to the Targets, which have a ground level of 52 feet. I have to mentally know, that i want to release at 400+52, so let's say 450 at pickle. However, since i'm trying to keep the plane steady, i don't want to change my pitch angle so many times. I therefore substract 131 from 52, let's call it 80feet difference. So from that, if i fly at 450+80, 530feet, i should arrive at my target's position in the eyeball of 450feet (400 + ground), for a release at "400".

 

My brain hurts. But when i do this, it works out. I get pretty damn good splash at that.

However... i needed to know how high the target was prior to working this out. And a few seconds to write that down on a scratch pad, which is not easy with no auto-pilot and VR headset :music_whistling:

 

 

Thanks for your thoughts,

 

Edited August 5, 2016 by Thisdale
Typo, 177 mils instead of 172, which is the correct value.

[gospadin]

Briefing would tell them, or they'd extrapolate from tables. Yes, accuracy is limited. Against soft targets like trucks, a Mk-82 probably needs to land within about 10m. Fragmentation bombs have a higher blast radius against soft targets, but less penetrating power.

 

Note that your deviation is a function of the dive angle. At a 90 degree angle, your drop altitude doesn't affect the impact site (ignoring wind).

 

Radar altimeters started to be a common thing in Vietnam I believe, possibly a bit earlier.

 

Modern planes can use radar altimeters, laser rangefinding and trigonometry to determine target altitudes, or just use GPS if they have that capability or don't want any energy emissions.

[gospadin]

Also, the F-10 map can give you the altitude at a point. You can use this to simulate having a kneeboard map or chart that the pilots might have had.

[autogyro]

How'd you work out 177 mils?

 

I'm seeing for 400 KTAS release, assuming full load, roughly

 

ZSL AoA = 56 + 16 + 0 - 35 = 37

 

Sight depression = 37 + 183 (from Bombing table, 0 degrees 400 KTAS 400 ft release)

 

= 220.

 

Edit: I guess flying at 480 KTAS with a lighter load will be about closer.

 

ZSL AoA = 5 (centerline store and sidewinders, assuming 18000 lbs)

 

Sight depression = 156

 

And for 440 KTAS with a full load

 

ZSL = 15

 

Sight depression = 186

Edited August 4, 2016 by autogyro

[lmp]

Quoting Wikipedia (https://en.wikipedia.org/wiki/Laser-guided_bomb):

It was determined that 48% of Paveways dropped during 1972–73 around Hanoi and Haiphong achieved direct hits, compared with only 5.5% of unguided bombs dropped on the same area a few years earlier. The average Paveway landed within 23 feet of its target, as opposed to 447 feet for gravity bombs.

 

Those numbers don't paint the whole picture of course but illustrate one thing quite clearly. Dumb bombs are inherently inaccurate and there's no way around it. Even if you know the target altitude down to the meter and you perform your attack perfectly, there's no way you can account for all the variables, such as wind (local direction and strength at all altitudes between you and the target, gusts) or local differences in air pressure (affecting your altimeter reading).

 

That said, if you're looking for accuracy, you chose the worst possible delivery profile (except maybe toss bombing). If the terrain, weather and air defenses permit, bomb out of a dive. And don't expect every bomb to go through the commander's hatch of the tank you aimed it at.

[Thisdale]

How'd you work out 177 mils?

 

 

Actually, small typo, meant to write 172.

I use the F5 manual's release tables.

 

[autogyro]

Actually, small typo, meant to write 172.

I use the F5 manual's release tables.

 

 

Unfortunately you can't simply use the bombing tables as the number you input into the Sight Depression setting. You have to adjust from 0 mil setting down to angle of attack and add that to the Bombing Table value.

[Stretch]

The Mission Planning form they give you looks a lot like a 1040 form and basically lets you calculate a final reticle depression taking all factors into account. I'm going to give that a try and see how it lines up with the sim.

[IvanK]

Biggest Issue is Altimeter Lag. Using the Weapon manual to calculate depression works well in in the SIM IF you allow for the excessive Altimeter lag. Its around 300ft for 10-20 deg Dive angles and 410feet for 45 deg angles. Should only be in the order of 80-110ft. So say you are working out a 20deg Dive angle pass with a release altitude of 2500ft. work out the numbers for this then when you fly you need to pickle at 2800ft Indicated which results in a 2500ft Actual release altitude. ... there is quite a thread on this subject.

[Thisdale]

Unfortunately you can't simply use the bombing tables as the number you input into the Sight Depression setting. You have to adjust from 0 mil setting down to angle of attack and add that to the Bombing Table value.

 

well, in the example i give, i get pretty much spot-on result. Adjusting for the altitude (which is the reason for my OP).

 

So far the Tables have been very effective.