Chinese Hypersonic Developments (HGVs/HCMs)

Hyper said:

Also it is larger than df-17.

Click to expand...

It is only longer but much thinner at 0.88m, while for reference DF-21 that uses the same TEL as DF-17 is 1.4m. So volume wise (fuel capacity) LRHW may not be as large as it seems.

Forget what is seen in images. Dimensions are a much more reliable. And that photo is a test stand. Not an operationall launcher.

Click to expand...

That photo seems to be an operational launcher, otherwise, they wouldn't have tried but cancelled a test launch with it. Or you would be saying that the military used a totally different mockup to train soldiers how to operate a real thing?

Wiki link guessed 0.88m diameter. This official mockup seems to corroborate, the maximum diameter including the fins would be about the same as the booster.

It is a MARV head and not an HGV. The DF17 has a more complex geometry than a cone at the end of a cylinder

taxiya said:

It is only longer but much thinner at 0.88m, while for reference DF-21 that uses the same TEL as DF-17 is 1.4m. So volume wise (fuel capacity) LRHW may not be as large as it seems.

Click to expand...

This is wrong. The DF-17 doesn't use an identical TEL to any other DF series missile but its very similar to the DF-16 TEL, and quite different from the DF-21 TEL, which is clearly cold launch.

totenchan said:

This is wrong. The DF-17 doesn't use an identical to any other DF series missile but its very similar to the DF-16 TEL, and quite different from the DF-21 TEL, which is clearly cold launch.

Click to expand...

I was talking about the diameter, so length difference of the canister is the cold launch cartrige which doesn't matter for diameter.

I didn't bother much to find a DF-16 TEL photo, but since you mentioned it, here the comparison comes. They are all 5x5 TELs, same wheel size, same gap between the 2 and 3 axises. How big difference between the two TELs? If you examine them, they are identical vehicles.




BTW, you seem to believe that DF-17 is a DF-16 replaced with a HGV warhead. I would say there is no base to support that except their numbers are sequential like DF-15 to DF-16 which means nothing. This is actually the position that US military analysists took that led them to conclude the range of DF-17 being kind of short. However, I disgree with that position on the ground that there is nothing to support such connection except the meaningless numbers. Also I am not sayng DF-17 is a DF-21 with a new warhead.

taxiya said:

I was talking about the diameter, so length difference of the canister is the cold launch cartrige which doesn't matter for diameter.

I didn't bother much to find a DF-16 TEL photo, but since you mentioned it, here the comparison comes. They are all 5x5 TELs, same wheel size, same gap between the 2 and 3 axises. How big difference between the two TELs?

Click to expand...

The DF-21 is cold launch, while the DF-16 is hot launch. Because the DF-17 also appears to be hot launch, and also considering the TEL shown in the parades 100 percent does not have the ability to cold launch, I think the similarities to the DF-16 are way more significant.

chinois49 said:

It is a MARV head and not an HGV. The DF17 has a more complex geometry than a cone at the end of a cylinder

Click to expand...

According to the materials released by Lockheed, the LRHW does follow a Sanger (?) trajectory, with a proper glide phase. That is a proper HGV.
Relative advantages aside, I don't see the point in trying to gatekeep glide vehicles based on shape when the actual trajectory is what matters. The line between MARVs and HGVs is pretty thin, but the LRHW clearly has fins with more surface area than what something like the DF-21 or DF-26 has. The shape of the boosters is also very different, so trying to compare these systems 1-1 isn't possible unless we get some more official data from both sides.

totenchan said:

According to the materials released by Lockheed, the LRHW does follow a Sanger (?) trajectory, with a proper glide phase. That is a proper HGV.

Please, Log in or Register to view URLs content!

Relative advantages aside, I don't see the point in trying to gatekeep glide vehicles based on shape when the actual trajectory is what matters. The line between MARVs and HGVs is pretty thin, but the LRHW clearly has fins with more surface area than what something like the DF-21 or DF-26 has. The shape of the boosters is also very different, so trying to compare these systems 1-1 isn't possible unless we get some more official data from both sides.

Click to expand...

MaRVs can also perform pull-up maneuvers and limited hypersonic glide. The issue with conical vehicles is they have a lower glide ratio than wedged ones, but have easier controllability, so they seem to have opted for that in the design process to save effort/time/money & avoid having to solve that problem.

Fins/wings can compensate for that some but I'm pretty sure they'd have to be quite large to fully make up for a rounded vs flat (lifting) bottom..

Also, the DF-16 is a very large missile for a nominal SRBM. Its range is probably on the lower end of MRBM.

totenchan said:

The DF-21 is cold launch, while the DF-16 is hot launch. Because the DF-17 also appears to be hot launch, and also considering the TEL shown in the parades 100 percent does not have the ability to cold launch, I think the similarities to the DF-16 are way more significant.

Click to expand...

Cold launch is the capabiliy of the canister not the missile, so IMO the similarity is no more significant than the numbers being adjacent. I must emphasize that my point is that "I don't see convincing base to make connections between DF-17 and either DF-16 or DF-21". But I think we have agreed that the diameter is settled, right?

[edit]
I will rephrase my point as "effort of relating DF-17 with any existing missile is wrong on technical terms". A HGV has vast different trajectory than any ballistic or quasiballistic missile. The first input is the payload weight, the altitude and velocity to begin gliding, the desired no-escape zone of the target. These determines the size of the booster and thrust of engines. By the time you get the desired parameters of the booster, you would not find any existing missile booster to fit the bill. You will be designing a totally new missile. The idea of DF-17 is developed from an existing ballistic missile is doing the math in reverse. The only thing one can get is the size of the booster by eyeballing. And the only relationship DF-17 has with anything else is the same fuel, motor and TEL.

ismellcopium said:

MaRVs can also perform pull-up maneuvers and limited hypersonic glide. The issue with conical vehicles is they have a lower glide ratio than wedged ones, but have easier controllability, so they seem to have opted for that in the design process to save effort/time/money & avoid having to solve that problem.

Click to expand...

I believe the difference is that the HGV is skipping off the atmosphere for range, while a MaRV uses its fins to pull up while in the atmosphere. I do agree with the downsides of the conical shape though, but I do wonder if part of the reason for the difference in shape is the DF-17 using a different trajectory from the LRHW. If the difference really is a Xian Quesen versus Sanger trajectory, my hunch is that the DF-17 is using the former mainly because it has characteristics that make it harder to intercept, while Lockheed may have settled for the Sanger trajectory even if its terminal stage is quite similar to a normal MaRV partially because of the lack of fielded dedicated ABM systems by adversaries at the time development of the LRHW started.

ismellcopium said:

Also, the DF-16 is a very large missile for a nominal SRBM. Its range is probably on the lower end of MRBM.

Click to expand...

I think the DF-16 is well into the MRBM category, its demonstrated range has been significantly greater than older estimates from Western sources.

taxiya said:

Cold launch is the capabiliy of the canister not the missile, so IMO the similarity is no more significant than the numbers being adjacent. I must emphasize that my point is that "I don't see convincing base to make connections between DF-17 and either DF-16 or DF-21". But I think we have agreed that the diameter is settled, right?

Click to expand...

Yeah, the diameter should be pretty similar.

taxiya said:

These determines the size of the booster and thrust of engines. By the time you get the desired parameters of the booster, you would not find any existing missile booster to fit the bill. You will be designing a totally new missile. The idea of DF-17 is developed from an existing ballistic missile is doing the math in reverse. The only thing one can get is the size of the booster by eyeballing. And the only relationship DF-17 has with anything else is the same fuel, motor and TEL.

Click to expand...

Isn't the main difference after the boost stage though? The boost stage should still be similar, so I think an existing ballistic missile's boost stage should still be usable. The DF-16 should be a relatively advanced missile, so its motor should be quite capable.

totenchan said:

Isn't the main difference after the boost stage though?

Click to expand...

No. The difference started from the ground, different launching angle (not vertical), different burn time for different altitude of separation. These are the only things I am willing to give. More details are discribed in many pages in a perfessional book which I consider should not have been available to the general public.

totenchan said:

The boost stage should still be similar, so I think an existing ballistic missile's boost stage should still be usable. The DF-16 should be a relatively advanced missile, so its motor should be quite capable.

Click to expand...

No, because of the above. Regardless how capable DF-16 is, modifying it to become DF-17 is like modifying a pickup truck into a sedan, you won't get the comfort and performance of a sedan.