Chinese Hypersonic Developments (HGVs/HCMs)

taxiya

Brigadier
Registered Member
Df-zf is hgv not a waverider.
Ah that would be my mistake in the semantics. I assumed waverider can be powered or unpowered and glide vehicles are a subset of waveriders but it seems the universal(not agreed upon) definition for waverider is powered and makes use of propulsion.

The semantics between waverider and boost glide us poor though. You could technically have boosted hgv that is propelled and makes use of aerodynamic lift but there's no boost waverider group even though such a thing can be its own.

So Xiamen unis project makes use of "dual wave riding" but is unpowered. Df-zf is boost glide but may also make use of shockwaves, no one knows much about df-100 here except that it's powered. The aircraft is unknown. The global ranged flight however is most likely a waverider if it flew within the atmosphere and around the world at nearly mach 20 avg speed.
From this paper by "National University of Defense Technology of China", It seems to me that HGV is unpowered waverider, at least in Chinese terminology. From my understanding of waverider's characteristic, I believe the Chinese terminology is shared by scientists in other countries.

Note, the paper was published in English in European Conference of Aero-Space Sciences, so the scientists are talking in same terms.

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Abstract
Hypersonic gliding vehicle is attracting an increasing attention because of its high lift-to-drag ratio and high cruising speed. Based on the design theory of cone-derived waverider, this paper proposes a novel design approach of hypersonic gliding vehicle, which is accommodated in a wide speed range. The parametric method employed in ascender line makes it possible to control the overall configuration. Numerical analysis demonstrates that this kind of aircrafts own good wave-ride properties in the designed speed range. The simplified trajectory performance analysis shows a wavy trajectory with long range, which makes it suitable for long-distance transportation and tactical defense penetration.


A wave-rider is defined by its body shaping to gain lift at high speed, a HGV does exactly that. Powered or not isn't a criterion. This is the same as in aircraft, a glider is still an aircraft even un-powered because it get lift by wings just like others.
 
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taxiya

Brigadier
Registered Member
USAF's weapon claims Mach 20 top speed and 1600 km max range. Compare this to Mach 10 DF-17 which achieves a 2500 km range. A few possibilities:
1- USAF's weapon has a horrible lift to drag ratio, resulting in a short range.
2- It can't do normal glide so it has to perform skip glide. This involves constant altitude changes meaning horrible range.
3- It uses a lower trajectory than the DF-17 which apparently uses the 40-55 km range. This would mean a superior weapon but I don't see the US shooting for this at its first hypersonic. Mach 20 combined with a lower trajectory means incredible heat.

I think it is a combination of these. A top speed of Mach 20 would require a huge rocket in any case and making the weapon light enough would require a lot of innovations. Interestingly, most failures we hear so far are rocket motor related.
I think your first 2 points are enough to say everything. Higher speed with shorter range means it does not glide/fly well but more closer resembling a cone shaped reentry vehicle flying a trajectory closer to ballistic which reaches higher speed but then shorter range compared to it would have been if it could glide better.

I highly doubt it can skip glide which is even more challenging than a better constant gliding in the air.
 

taxiya

Brigadier
Registered Member
It's a bit off-topic definitely, but at the same time kinda something that can be talked about here?

Like comparisons, implications etc? Although I suppose best would be a dedicated thread for US hypersonics (do we have such a thread though? or if we do, how old and untouched is it lol).
I personally agree that technical discussion will inevitably lead to comparison which should be tolerated so long as everyone stay within the technical boundary.

But those two twitter posts have no technical contents at all, rather look like provoking political fight.
 

supercat

Major
The hypersonic vehicle flew 40,000 km (25,000 miles) for more than 100 minutes, Richard wrote in the testimony -- the most detailed U.S. account of the test to date. It was “the greatest distance and longest flight time of any land attack weapon system of any nation to date,” according to the testimony. Richard gave similar testimony to both the House and Senate Armed Services Committees last month.
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BoraTas

Major
Registered Member
USAF's weapon claims Mach 20 top speed and 1600 km max range. Compare this to Mach 10 DF-17 which achieves a 2500 km range. A few possibilities:
1- USAF's weapon has a horrible lift to drag ratio, resulting in a short range.
2- It can't do normal glide so it has to perform skip glide. This involves constant altitude changes meaning horrible range.
3- It uses a lower trajectory than the DF-17 which apparently uses the 40-55 km range. This would mean a superior weapon but I don't see the US shooting for this at its first hypersonic. Mach 20 combined with a lower trajectory means incredible heat.

I think it is a combination of these. A top speed of Mach 20 would require a huge rocket in any case and making the weapon light enough would require a lot of innovations. Interestingly, most failures we hear so far are rocket motor related.
Mods, I am sorry if this is off-topic. But this topic has been talked about a lot so I dug it up a little bit. I also believe this info is important because it is useful while speculating about Chinese hypersonics. My conclusion is the ARRW's Mach 20 speed is probably a fan fantasy. The wiki page lists the ARRW's speed as Mach 20+
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It references this rather low quality popular mechanics article for that claim
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And that page references this article which shows no references. It references itself!
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Then I continued looking up ARRW articles and pages about it. Lockheed Martin's fact sheet only claims 5+ Mach.
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But on their website there is an illustration that includes the HTV-2, a US hypersonic tech demonstrator from 2010. It seems the HTV-2 is the vehicle that saw Mach 20 speed. Then I found another low quality article from popular mechanics. Yes, also the same author. This time the article is really low quality.
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It speculates that the program is nearly identical to the HTV-2. It seems the logic is:
The program is nearly identical to the HTV-2 so the ARRW's speed must be Mach 20.
No references were provided.

The HTV-2 DARPA article is archived here:
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The program doesn't look similar at all. The HTV-2 was a test mule for the FALCON program. That program was aiming to develop global rapid conventional strike capability.
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The HTV-2 was launched by this:
1649210543894.png

I don't know you but to me, this doesn't look like something you could load 30+ of to an aircraft.

Summary: The ARRW's speed is internet speculation with no basis. I think we should stop talking about American weapons on this thread after this point.
 

ougoah

Brigadier
Registered Member
What else? I only know about df-100

The Chinese hypersonic test flight that according to the US state, flew "(around) 40,000km in over 100 minutes".

This is basically the range of one circle of the globe along its maximum distance (no doubt it didn't do a straight line flight though but the range and discussions on it use the 40,000km distance covered to basically indicate global range) and in over 100 minutes could mean any amount of time that's reasonable but probably means between 100 minutes and 150 minutes. This means an average speed throughout that roughly 2 hour long flight is between Mach 15 and Mach 20. This is an average speed, not top speed.

DF-100 is a HCM in the sense that it is powered (propelled) but it doesn't look like it's a waverider or glider and the suggested range is nowhere near global. There isn't much info on this platform except that it's hypersonic and a "cruise missile". So apart from the DF-ZF seen on the DF-17 and the DF-100, there are other hypersonic projects, weapons or not. Most of them we only hear of tests or statements from US or China.
 

Hyper

Junior Member
Registered Member
The Chinese hypersonic test flight that according to the US state, flew "(around) 40,000km in over 100 minutes".

This is basically the range of one circle of the globe along its maximum distance (no doubt it didn't do a straight line flight though but the range and discussions on it use the 40,000km distance covered to basically indicate global range) and in over 100 minutes could mean any amount of time that's reasonable but probably means between 100 minutes and 150 minutes. This means an average speed throughout that roughly 2 hour long flight is between Mach 15 and Mach 20. This is an average speed, not top speed.

DF-100 is a HCM in the sense that it is powered (propelled) but it doesn't look like it's a waverider or glider and the suggested range is nowhere near global. There isn't much info on this platform except that it's hypersonic and a "cruise missile". So apart from the DF-ZF seen on the DF-17 and the DF-100, there are other hypersonic projects, weapons or not. Most of them we only hear of tests or statements from US or China.
25K km not 40K km
 
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