Read the forum code of contact
By: - 2nd December 2007 at 16:36 Permalink - Edited 1st January 1970 at 01:00
You might find this interesting:http://srmsc.org/pdf/004431p0.pdf
There are more pdf-files here, maybe others contain more info for you: http://srmsc.org/ref1020.html
Fascinating stuff.
Looks like the test flight programme showed that Sprint did that very unusual thing for a miisile - exceed required parameters.
I especially liked the comment that one intercept actually 'achieved physical contact'. Not a great need for proximity take-out technology there, then!
No wonder the Soviets were scared ****less of the thing.
By: - 2nd December 2007 at 16:51 Permalink - Edited 1st January 1970 at 01:00
When you test the $hit out of something you get a good product. Many don't seem to realize you don't get that from the very first test round in the program. ;)
By: - 2nd December 2007 at 19:17 Permalink - Edited 1st January 1970 at 01:00
Awesome rocket :eek:
By: - 2nd December 2007 at 20:00 Permalink - Edited 1st January 1970 at 01:00
Any idea on the top speed of Sprint? Most sources say Mach 10 but one I saw said Mach 17 and I've got an AIAA paper here where they discuss doing tunnel tests on the HEDI upper stage at up to Mach 14. Where HEDI used Sprint motors (as I recall) but it added lots of fins (weight and drag) and a nose that was hardly streamlined (lots of drag) it would seem to be within the realm of possibility.
By: - 2nd December 2007 at 21:12 Permalink - Edited 1st January 1970 at 01:00
By: - 2nd December 2007 at 21:55 Permalink - Edited 1st January 1970 at 01:00
Somehow I doubt Sprint did more than Mach 10, it was intended to hit RVs as low as 1500m AGL and I'd say much more than 3km/s (coincidentally the same speed as a RV at low altitude, it seems) would be seriously pushing the limits of thermal protection technology with such a sharp nosecone. Some sources also quote an acceleration capability of up to 200g which seems equally questionable, so there does seem to be some less than trustworthy info out there.HEDI (= High Endoatmospheric Defense Interceptor) would not be expected to be subject to the same heat loads, I'd say. OTOH, there are indications that Gazelle does up to 5km/s, but considering its rumoured weight and range it might be intended for higher interception altitudes than Sprint as well. These two missiles sure are the most fascinating and secretive projects around :(
Perhaps these very high speed and acceleration figures are based on confusing the actual Sprint missile with data for the related high-altitude HEDI and very much experimental HIBEX missiles?
No. Like I said ONE source said Mach 17 (I don't know how reliable the source is). I'd initially dismissed it but then later read about the Mach 14 testing of HEDI. I'd skimmed the paper ( AIAA 92-2758 Endoatmospheric Interceptor Test Capabilities in the NSWC hypersonic Tunnel #9) and saw this:
"HEDI KV Stability Tests (1987)
This experiment investigated the static
stability and drag of the HEDI KV and KV with the
second stage booster. Simultaneous force and
moment, heat transfer, and pressure measurements
were obtained as the subscale model was swept
through angles-of-attack from -15deg to + 15deg . Test
data were obtained at Mach 10 and 14 for a range of
Reynolds numbers."
going and reading it a bit closer the following was mentioned a few pages earlier:
"Shear Layer Radiation Tests (1978)
Infrared radiation was measured emanating
from a turbulent shear layer of a slot cooled
interceptor forebody as shown in figure 3. Since the
tunnel working fluid, nitrogen, has no infrared
absorption bands, it was necessary to either seed the
freestream or the coolant flow with a gas that
radiates. CO2 was added to the coolant injected
tangentially over the window. For some of the runs,
CF, was added in the heater, thus seeding the tunnel
freestream. Radiation intensities and statistical
properties of the fluctuating radiance were measured
with internally mounted radiometers. These tests
were performed at Mach 14 which simulated the
flight velocity of 6500 ft/sec at an altitude of 95,000
ft."
This could explain the Mach 14 figure in the test performed 9 years later.
As for the rest:
Sprint:
Generally given as Mach 10 with 100G acceleration, 25 mile range.
HEDI:
Generally given as 200G acceleration
HIBEX:
Generally given as 400G acceleration
To get much more than that and some basic dimensions you have to do a little digging.
From "DARPA Technical Accomplishments Volume II" the following is available on HIBEX:
Burnout velocity: ~2.6 km/sec.
Burn duration: 1 sec
377 G acceleration
300 lb payload
490,000lbs thrust
Below from L-R: HiBEX, Sprint, and HEDI
By: - 2nd December 2007 at 22:02 Permalink - Edited 1st January 1970 at 01:00
http://www.youtube.com/watch?v=nLpLEgAS574
It's too bad that clip didn't go a few seconds longer as you get to see the nose of the upper stage start glowing white hot. The clip is from "Nukes in Space" as I recall.
By: - 3rd December 2007 at 19:25 Permalink - Edited 1st January 1970 at 01:00
No, what? How does any of this contradict the contents of my post? BTW, I was not suggesting that you were mixing up said missile projects but that the sources quoting unusually high figures for Sprint's top speed and acceleration might be. My bad if my words failed to make that clear.
The Mach 17 source was published before HEDI existed.
By: - 4th December 2007 at 19:03 Permalink - Edited 1st January 1970 at 01:00
May be HEDI did 200 g at the end of its path. As far I know, it was IR guided. So, with such an extreme acceleration in the thick layers of the atmosphere it would be blinded. Also, its big fins will “burn”. Obviously above 20.000 m such problems are considerably lighted. Just my opinion. Had HEDI loitering capability? On the other hand Sprint would have capability to intercept at lower levels.
It will be interesting to know burn-out times and speeds to made some guess about peak and average accelerations.
By: - 5th December 2007 at 19:40 Permalink - Edited 1st January 1970 at 01:00
May be HEDI did 200 g at the end of its path. As far I know, it was IR guided. So, with such an extreme acceleration in the thick layers of the atmosphere it would be blinded.
Unlike THAAD which has a cover that blows off at altitude, HEDI used boundry layer cooling to keep the IR window "cool". Cold nitrogen gas was ejected ahead of the window to form a cooler layer to protect the window. Even still it was a race to hit the target before the window failed. Also, a diagram of one of the tests show it intercepting a target at 49,000 feet (that was the plan, as far as I know any test results haven't been released).
Also, its big fins will “burn”.
I'm sure they considered that in the design. The composite strakes on SM-2/3 char but that's accounted for.
Had HEDI loitering capability?
Loiter??? Think of HEDI as being a hit-to-kill version of the Sprint. Same motors and the fins are there simply to counter the destabilizing effect of the larger forward area. 2nd stage even has the same four maneuvering fins with four more in between, again to counter the larger forward area.
On the other hand Sprint would have capability to intercept at lower levels.
Same basic envelope.
By: - 5th December 2007 at 20:11 Permalink - Edited 1st January 1970 at 01:00
May be some improvements considered to be introduced in the 70s Sprint-II were inducted to the HEDI.
Development and interest in Sprint did not end with the flight testing of the missile. Martin was awarded a definition study contract for Sprint II in May 1971. This was followed by a design contract in October 1971. In May 1972 a contract worth $168 million was signed for the development and flight testing of Sprint II. The main improvements of the Sprint II missile included greater accuracy, a manoeuvring capability three times greater than the original Sprint, improved reliability, hardening and strengthening against the increased manoeuvring forces and the final improvement included a faster launch process. No known launches of Sprint II were done, and investigations into such a missile were completed during 1983 as non-nuclear forms of ABM defence started taking precedence.
After all HEDI was a later 80s thech rocket. So, a 200 g, infeasible by late 60s would become feasible 20 years later.
By: - 6th December 2007 at 03:11 Permalink - Edited 1st January 1970 at 01:00
May be some improvements considered to be introduced in the 70s Sprint-II were inducted to the HEDI.After all HEDI was a later 80s thech rocket. So, a 200 g, infeasible by late 60s would become feasible 20 years later.
You should probably take a closer look at the timeline and what was actually written. HiBEX was well BEFORE Sprint. HEDI used the SAME motors as Sprint.
By: - 6th December 2007 at 12:56 Permalink - Edited 1st January 1970 at 01:00
But HiBEX was a very short range ABM. HEDI: High EndoAtmospheric...
By: - 6th December 2007 at 19:31 Permalink - Edited 1st January 1970 at 01:00
But HiBEX was a very short range ABM.
And?
HEDI: High EndoAtmospheric...
"Same motors as Sprint"
Posts: 198
By: Jolanta Nowak - 2nd December 2007 at 14:53
I've had an interest for some time in the Safeguard ABM system and particularly in the 'last ditch' Sprint missile.
All accounts I've read point to a bird which was formidable in performance. The shots of reaction take offs which you can still find on the net are absolutely stunning and I have doubts as to whether there's much in the modern arsenal to match the thing.
What is short on the ground (at least, I can't find it) is much data on interception trials and kill rates. Can anyone point me in the right direction?