Side-by-side comparison of the waverider (left) and biconical (right) HGV variants of the DF-17 at nearly the same view angle. Posted by Hainan Homosexual Guy on Weibo.
Chinese Hypersonic Developments (HGVs/HCMs)
- Thread starter A.Man
- Start date
I've been so confused over the last few days due to the unusual orientation of the HGV tipped DF-17 until I saw Holehole's latest explanation:
What everyone was expecting thanks to 2019 parade
What was actually seen in the latest video
Holehole's explanation on how the TEL actually works
Note that both the mock up displayed in 2019 and the scale model he used above depicts the HGV with 3 fins, where as it turns out the real thing has four fins including one on the belly of the HGV. Here's a shot of it with the belly fin clearly displayed:
I suppose it's done so there isn't a fin that sticks straight down on the TEL to make the shape easier to handle, or alternatively no fin sticking straight up to make the enclosure around it taller than it needed to be. Not sure if there's any significance for foreign intelligence agency if they were also tricked for the last 7 years.
I was thinking in my mind that maybe the rocket sat on a turntable that could be rotated once it's vertical thanks to the 2019 display. Made zero sense since you'll just turn the whole TEL instead. Now the new mental model it makes sense.
What everyone was expecting thanks to 2019 parade
What was actually seen in the latest video
Holehole's explanation on how the TEL actually works
Note that both the mock up displayed in 2019 and the scale model he used above depicts the HGV with 3 fins, where as it turns out the real thing has four fins including one on the belly of the HGV. Here's a shot of it with the belly fin clearly displayed:
I suppose it's done so there isn't a fin that sticks straight down on the TEL to make the shape easier to handle, or alternatively no fin sticking straight up to make the enclosure around it taller than it needed to be. Not sure if there's any significance for foreign intelligence agency if they were also tricked for the last 7 years.
I was thinking in my mind that maybe the rocket sat on a turntable that could be rotated once it's vertical thanks to the 2019 display. Made zero sense since you'll just turn the whole TEL instead. Now the new mental model it makes sense.
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Bro just used my drawing.. Dammit I knew I should've put a watermark, I literally also had this epiphany myself a week ago.
For the record, it's been known that there was a fin underneath the belly. Many models just got it wrong
You've misunderstood the technical principle of GPS signals in tactical missile launches. You don't need military-grade GPS signals to improve accuracy.
What GPS actually measures is not the vehicle's precise position, but its velocity and position during the ascent phase. By using these signals to plot continuous spatial coordinate points, you can obtain a highly accurate ascent trajectory curve. GPS accuracy of 100 meters is far superior to the older method of radio command correction—placing two radio transmitters at specific angular offsets behind and to the side of the launch site, with the missile's onboard receiver measuring the difference between the two radio signals to determine whether it is flying along the pre-planned ballistic trajectory (this was the scheme used in the V-2 era). For the method China employed from the 1970s through the 1990s, the launch-phase navigation accuracy was definitely inferior to GPS. Even the deployment requirements for those two radio transmitters meant that a slight mistake could introduce errors far exceeding those of the GPS solution (100 m). The advantage of GPS is that the error is constant regardless of flight distance—whereas with radio, it is not. Moreover, GPS requires less equipment and makes mobile launch positions much more convenient.
First of all, you’re deliberately confusing the two concepts. A moment ago, you were talking about GPS-guided technology, not GPS-assisted measuring—which is a completely different concept from GPS guidance.
And your claims about China's missile measurement technology in the 1990s are complete nonsense.
I don’t know which tabloid you got your “evidence” from claiming that PLARF was still using WWII-style dual-transmitter radio correction in the 1990s. Doppler radar has been standard technology since the 1960s. China already had ballistic missiles with accuracy far superior to that of the V-2 long before GPS came into use, so please stop spouting nonsense.
By the way, which tabloid did you read that the U.S. shut down GPS signals in the Taiwan Strait in 1996?
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Regarding the role of GPS in the ascent phase, you can look up literature from the 1990s. Twenty years ago, a lot of what we knew about the guidance of Chinese Rocket Force missiles was told to us by the editor of Inertial Worldmagazine during private gatherings (200X).Don't get too mistaken about the timeline and cycles of Chinese radar technology breakthroughs.
Back in the 1980s–90s, the radar technology of Chinese defense-industrial enterprises—whether ground-based or airborne—was extremely backward. Many advanced architectures[*] were only at the prototype stage. Back then, China's analog tech wasn't up to par, and digital tech was just beginning to spread. There was none of that "advanced tech" you imagine.
Most electronic technologies only entered service after 2000.
I haven't even told you yet about the production of advanced inertial navigation systems back then—the production of inertial guidance systems for long-range ICBMs, especially the calibration and testing issues, the output issues (also told to us by the Inertial Worldeditor). A lot of things were more backward than you think. And back then, missile programs had to control costs—there weren't any advanced components to speak of. How could you think a technology that the West popularized in the 1960s, China could already popularize in the 1980s–90s? Especially in the short-range tactical ballistic missile sector (these were all 1980s–early-90s Chinese tech—back then China couldn't even make CRT TV tubes or air conditioners properly. In the 80s, how many defense electronics factories switched to civilian production, even had factory directors defect to the West). Where would the money come from for new tech and new equipment? Just keeping the troops' combat readiness going was already something. Those years the military was even running commercial sidelines—you forgot?
As for China digesting the APG-66 radar from the F-16 (the J-8II program in the 1980s—tech docs were given in the 80s, and a physical radar in the early 90s), China's copy didn't reach maturity until the late 90s. Basically, the avionics on the J-10 prototypes are said to have been straight F-16 originals (that symbol-generator LCD and the HUD). So yeah, the late 20th century was indeed pretty bleak.
You're still deliberately misinterpreting the meaning of this term.
Is what you're talking about the same thing as what people commonly refer to as a GPS-guided missile?
Please clarify exactly what you heard at this private gathering. Is PLARF still using the dual-transmitter radio correction from ww2 era?
The V-2 has a CEP of 10–17 km at a range of 320 km, which corresponds to a deviation of roughly 3–5% . In contrast, the DF-3—which China deployed in the 1970s and exported to Saudi Arabia in 1988—has a range of 3,000 km and a CEP of 1.5–3 km, with a deviation not exceeding 0.1%. With a range 10 times that of the V-2, its accuracy has improved by an entire order of magnitude. Could this have been achieved using the supposed primitive correction technology from World War II that you mentioned? Or does the missile sold to Saudi Arabia actually have a CEP of 100 km?
In 1980, China conducted an ICBM test with a total range of 9,070 km. The target area was a 2x2 km² square region in the South Pacific, and the actual impact point was only 250 m from the center of the target. Based on the V-2’s accuracy, wouldn’t that target area have to be a 600x600 km² area? Please tell me, where was GPS back then??
This is the Yuanwang-1 tracking ship, responsible for tracking the warhead and the launch vehicle. Wasn’t the PLARF limited to dual-transmitter radio correction back then?
Tell me, according to this intelligence document declassified by the U.S., what is installed on the Yuanwang-1? Is it GPS or a World War II-era radio transmit? Wasn't this copy handed out at your private gathering?
No one denies that China’s BM and radar technology lagged behind that of the US and the Soviet Union at the time, but to say it was on par with Nazi Germany’s technological level—are you serious?
Do the difficulties you mentioned regarding China’s defense industry have anything to do with GPS? Are the F-16’s radar and ground-based tracking radar the same thing?
Why do you always write so much to dodge the issue when your errors have clearly been pointed out?
Let me ask again: What is your evidence for the claim that “the U.S. shut down GPS signals in the Taiwan Strait in 1996”?
Was that also a secret revealed at your private gathering??
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First, you need to be clear: we're talking about equipment used on launch vehicles and ICBMs. Is that the same as the tracking, telemetry and control (TT&C) used on short-range surface-to-surface missiles in the Taiwan Strait scenario?
Moreover, strictly speaking, these devices are not actually issued to standard Second Artillery Corps or Rocket Force combat units. These are technical support equipment for R&D, not systems configured for combat units. When they are fielded to operational units, a DF-5 launch primarily relies on high-precision floated-platform inertial navigation, combined with early precision surveying of the ground launch site. For the ascent phase, it canrely on such radio telemetry beaconing—or it can do without.
The cost and accuracy of an ICBM's guidance equipment are two entirely different things from those of a short-range tactical ballistic missile with a range of a few hundred kilometers. Placing two radio beacon transmitters behind and to the side of the launch site is actually a very simple and low-cost technical solution, and the equipment support requirements are relatively straightforward.
Accuracy isn't actually that hard a problem. The electronics technology of the WWII era and that of the 1960s–70s are vastly different. With some modern radio technology improvements, plus the application of transistors and integrated circuits, the sensitivity of the receiver becomes much better. The ability to receive, process, and identify radio signal differences also becomes far more precise.
This is much easier and simpler than Doppler radar technology—there's no complicated signal processing involved. In essence, the technical principle is: the onboard receiver picks up encoded information from two radio beacons. Simply decode it, compare the phase difference, and you know whether the missile has deviated from its ascent trajectory. The onboard flight controller then commands the rocket to correct its attitude, ensuring the missile keeps flying along the correct ballistic parabolic trajectory—that's all it takes.
Additionally, I just fed this issue and some related information to the GLM 5.2 model for verification. After a rigorous technical timeline analysis, it confirmed that what my source (the Inertial Worldeditor) told me is likely accurate (actually, if you search CNKI for relevant papers on tactical missile guidance systems from the 1990s, you'll get a pretty clear picture—I happened to study this topic back in the 2000s).
In the early stages of the DF-11 and DF-15, they probably inherited the inertial navigation system from the DF-2A, and they did require guidance radar radio correction (not the V-2-style beam riding—my wording on that point might have been off). This radar was likely a product similar to what the HQ-2 used.
Attached is the GLM 5.2 Chinese-language analysis.
The claim that turning off GPS over the Taiwan Strait caused problems for short-range ballistic missiles is impossible to verify—mainly because this information comes from the Taiwanese side.
From what I learned years ago, an older friend of mine had been working with GPS/GIS-related tasks in the military as early as 1992. Through him, I got to know many of the actual realities of early domestic GPS usage in China (mostly the big pitfalls encountered in applications).
Secondly, there is a wealth of information in CNKI literature about the inertial navigation technology challenges of that era. Before 2000, many advanced INS technologies were still under R&D.
China probably began developing new guidance schemes for tactical ballistic missiles around 1992 as well. The literature I've seen on using GPS for ascent-phase guidance likely dates from that development period. The missiles used for deterrence in the 1995–1996 Taiwan Strait crisis were probably this improved variant of the DF-15—I remember news reports at the time saying so. For that generation of DF-15, GPS solved the ascent-phase trajectory correction problem (since the inertial navigation base was still likely an improved version of the DF-2A's). GPS replaced the role of ground stations, because the goal was to reduce the number of launch support vehicles. Only this version of the DF-15 would exhibit the phenomenon the Taiwanese side described—that turning off GPS caused the missile's accuracy to degrade, with errors as large as 200 km. Of course, I think this might be a dramatization on the Taiwanese side.
I'm more inclined to believe that if such a situation actually occurred, it might have been because a sudden GPS outage or anomalous data caused an error in the rocket's ascent-phase data, triggering premature self-destruction. Back then, onboard missile computers were not advanced (many of these computers were programmed in assembly language, so abnormal data could easily cause logic errors in the program—and chronologically, the GPS installation on the DF-11/DF-15 was experimental, not standard production equipment). Therefore, I don't rule out the possibility that the GPS shutdown could have seriously disrupted the launches, as the claim suggests.
From what I learned years ago, an older friend of mine had been working with GPS/GIS-related tasks in the military as early as 1992. Through him, I got to know many of the actual realities of early domestic GPS usage in China (mostly the big pitfalls encountered in applications).
Secondly, there is a wealth of information in CNKI literature about the inertial navigation technology challenges of that era. Before 2000, many advanced INS technologies were still under R&D.
China probably began developing new guidance schemes for tactical ballistic missiles around 1992 as well. The literature I've seen on using GPS for ascent-phase guidance likely dates from that development period. The missiles used for deterrence in the 1995–1996 Taiwan Strait crisis were probably this improved variant of the DF-15—I remember news reports at the time saying so. For that generation of DF-15, GPS solved the ascent-phase trajectory correction problem (since the inertial navigation base was still likely an improved version of the DF-2A's). GPS replaced the role of ground stations, because the goal was to reduce the number of launch support vehicles. Only this version of the DF-15 would exhibit the phenomenon the Taiwanese side described—that turning off GPS caused the missile's accuracy to degrade, with errors as large as 200 km. Of course, I think this might be a dramatization on the Taiwanese side.
I'm more inclined to believe that if such a situation actually occurred, it might have been because a sudden GPS outage or anomalous data caused an error in the rocket's ascent-phase data, triggering premature self-destruction. Back then, onboard missile computers were not advanced (many of these computers were programmed in assembly language, so abnormal data could easily cause logic errors in the program—and chronologically, the GPS installation on the DF-11/DF-15 was experimental, not standard production equipment). Therefore, I don't rule out the possibility that the GPS shutdown could have seriously disrupted the launches, as the claim suggests.