Predator B to get SDB's

With a possible 60 mile stand-off glide range, and an accuracy of hitting within 1.5 meters of it's intended target, the Small Diameter Bomb is slated to be fitted on Predator B's in 2009.
That is right after the F-15E Strike Eagles are setup to deliver the 250 lb bombs.

source: C4ISR Journal; Oct/Nov 2006, page 15

But for 60nm on a Predator, that must be from a very high altitude. Part of that that just strikes me as a bit suspect. Not that I dont think its impossible.just seemed a bit improbable

Originally posted by firepilot
But for 60nm on a Predator, that must be from a very high altitude. Part of that that just strikes me as a bit suspect. Not that I dont think its impossible.just seemed a bit improbable

I agree with you, I would have thought that a range like that would be influenced by not only altitude but speed of delivery vehicle. But that is the way it is reported in C4ISR Journal. Then again what was the jump altitude and speed of delivery vehicle on the parachutist who glided across the English Channel wearing little wings on his back? The SDB as described has wings that pop out as well.

Getting to the truth of the matter would be a good challenge for our illustrious ATS knowledge base... anyone care to try?

I always thought that the 60NM standoff range was it's standard, meaning that high alt and speed was not factored in. A SDB dropped at subsonic (200 Kt) speeds from MQ-9 at altitude might have less range than 60NM but not by that much. However if I'm right then an SDB dropped from an F-22 might have a glide range near 100 miles.

Also, will the Reaper carry four or eight SDB's?


[edit on 10-11-2006 by WestPoint23]

Aircraft altitude and speed are definitely part of the factors to get that 60 mile range.

Since the Predator/Reaper will not be flying at high speed although could have a high altitude, I do not see a 60 mile range from any dropped from that plane.

Now if we are talking an F-22, now that I can see.

I can't quite see the point of using Predators to deliver something to a place it can't see. I thought the idea was that the Predator could do the whole business - find, fix, finish, and verify afterwards.

OTOH, a 250 lb would be a handy addition to its capabilities - but not as good as CLAWS would be.

We can work it out (approximately) handy enough.

Anyone got the launch speed and altitude for a flight of known length?

If I assume a launch speed of Mach 1.5 at 50,000ft gets you 60 miles, then...


Vlaunch = 990 mph
Hlaunch = 50,000ft

Travel distance is 60 miles or 316,800ft, giving an overall glide ratio of 1 in 6.3 (approx).

If I assumed constant velocity, it would be a flight time of 4 odd minutes - but this is not going to happen, the bomb will quickly drop down to subsonic speeds at terrible sink rates, then level off at its design condition and have glide ratios of 1 in 10 or so.

A glider has a glide ratio of around 1 in 15 - I doubt an SDB will be as good, so it sounds about right. A glider also goes well at around 50mph, with its slightly swept wings and greater sink rates, I'd reckon an SDB would operate at around 150-200mph


If you wanna do calcs, I'd go with a glide ratio of 1:10 with an error of +-2 [i.e. 1:8 to 1:12]


So a predator launching at 200mph at an altitude of 1000ft will be able to sling the bomb onto a target 10,000ft away [around 2 miles].

Originally posted by Wembley

I can't quite see the point of using Predators to deliver something to a place it can't see. I thought the idea was that the Predator could do the whole business - find, fix, finish, and verify afterwards.

OTOH, a 250 lb would be a handy addition to its capabilities - but not as good as CLAWS would be.

Dont be so sure it cant see out that far with some sensors. Besides, there are other ways to fix a position of something than with the same aircraft. Could be some other air or ground asset, even space based that came up with the target location, and feeds it to the Predator/Reaper.

Well, 60nm is 69 statue miles, so Kilcoo what would be the range of an SDB dropped from a Predator at 40-50K (cruise alt) and 200Kt (230 mph)?

None of us know, I am just sure it is a lot less than that 60 NM. Its probably classified too, at how the ranging algorithm is came up with. Just like with most weapons with a range like that, its usually never actually declared by anyone, so everyone else just guesses.

Originally posted by WestPoint23
Well, 60nm is 69 statue miles, so Kilcoo what would be the range of an SDB dropped from a Predator at 40-50K (cruise alt) and 200Kt (230 mph)?

Its not an exact science, I can't say [with the lack of info available!] exactly what the range is.


The above thing is just a guess, at a glide ratio of 1:10 it would give you 500,000ft (@50,000ft release) or 400,000 (@40K) which corresponds to 95 or 76 miles => obviously bull_hit.


Therefore I'd have to say my earlier guess of 1:10 (or even 1:8) appears very unrealistic, 1:5 [@ optimal airspeed] might be a better guess, giving a range of around 47 miles...

To say exactly how the L/D curve varies with speed [aka how much release speed affects things] is simply impossible without hard data and I'm not about to bother meshing up a SDB to see how it performs with CFD.

Kilcoo, I asked because I though I was doing the math wrong when I kept getting 95 miles, goes to show you, trying to figure out classified data is very hard indeed.

Originally posted by WestPoint23
Kilcoo, I asked because I though I was doing the math wrong when I kept getting 95 miles, goes to show you, trying to figure out classified data is very hard indeed.

We can't figure it out, but normally a decent guess can be made... [apart from my earlier crap! ]

By 2009 the SDB II will be ready, it has an improved and more capable seeker (mobile targets) and a two way data link, I wonder if the Reaper will be fitted with this one instead...