Chinese UAV & UCAV development


Totoro

Captain
VIP Professional
Here's a bit I just found about X-15 plane.
"The pilot would start a gentle pushover at about 70,000 feet for a heating flight so that he could level out at around 100,000 feet or less, and all control would be done with aerodynamic control surfaces. [58, p.189] For altitude flights, the pilots continued upward at a fairly steep angle and either continued to engine burnout or shut the engine down at a predetermined speed or altitude. They would spend two-to-five minutes out of the atmosphere in a weightless condition. [26, p.92] When above 200,000 feet, the aerodynamic controls had no effect, and pilots had to use the reaction control system for attitude control. [7, p.198] Speed flights would be done at the lowest altitudes, around 50,000 feet, and would have the longest ranges, around 400 miles. Control would be with aerodynamic control surfaces only. For speed flights, it was NACA practice to increase speed by one half Mach number for each successive flight. [15, p.322]"

100 k feet is 30.5 km. 200 k feet is 61 km. We also know that X-43 did have a controlled flight at 33 km. So, wz8 cruise altitude is likely between those two figures. Probably closer to 33 than to 61 km. Speed wise, who knows. X-43 did mach 9.6 at just 33 km. X-43 was perhaps more of a big scramjet missile than a real plane, though. So perhaps X-15 comparison is more apt. mach 6.7 at 31 km. Interestingly, due to controllability, X-15 had highest speed at said, fairly low altitude, even though it could reach much higher (100 km) in a ballistic trajectory. X-15 is also a good comparison due to its liquid rocket fuel engine. It used up 6.8 tons of rocket fuel in 80-90 seconds.
 

enroger

New Member
Registered Member
So can one deduce, from other similar projects, and the fact control surfaces are there, the altitude at which wz8 likely cruises? If we have the altitude pinned down, we also might have a better idea of the cruise speed as well. My personal guess is above 30 km altitude, but i'd like a more precise figure...

Don't we all... I'm dying of curiosity here. Think I might "simulate" it in ksp just to get some rough numbers.
 

Totoro

Captain
VIP Professional
Talking about the UCAV shown, here are some measurements, which i believe are fairly precise, as compared to known values of GJ-2 and Harpy Drone. The Wingspan works out at 13 m (one image 12 m, other image 14m, depending if GJ-2 was in the foreground or in the background) and length works out to 10.5 m.

Those are values slightly bigger than Neuron ucav demonstrator. It has 12.5 m wingspan and 9.5 m length. For those dimensions it was 4900 kg empty and had gross weight of 7000 kg, using a 40 kn engine. Gross weight is very likely NOT mtow weight though.

We could also compare it to X47b. 11.6 m long, 19 m wingspan. 6.3 tons empty, with actual mtow published of 20.2 tons. its f100-220U specialized variant engine had 71 kn of thrust.

We also know that less efficient designs, such as JF17, weighing 6.6 tons, can have a ferry range of 1880 nm (3480 km) with 4.6 tons of fuel.

So, i'd say it's safe to assume the following:
Sharp Sword is likely in the 5 ton empty range, very likely under 5.5 tons. So i wouldn't expect MTOW to be over 17-18 tons. Perhaps it's as little as 15 tons, who knows.

That still leaves 10 or so tons for fuel and weapons. Is it actually carrying that much fuel - who knows. MQ-25 does seem to be carrying at least 20 k pounds of fuel (9 tons) though it's not directly comparable in size or shape.

I would say 5 tons of fuel would be a low estimate, with the final figure going perhaps up to 7-8 tons. In theory there is even more volume in there, but as we saw on that one AVIC model of this new variant of Sharp Sword, it has two weapon bays which are around 1 cubic meter each in volume. So with other equipment, it's not unrealistic to expect the ucav has 2-3 tons of fuel less due to weaponization.

Assuming the model is accurate, weapon bays are 4 meters long by 0.5 meters. And a model of the weapon was shown inside, 3.3 m long bomb, 0.3 m in diameter. Comparing that to other bombs, that works out to perhaps a specialized bomb class - somewhere in between of 1000 lb and 500 lb bomb. Meaning probably 350 kg or so. Though, as the bomb was shorter than the bay itself, with seemingly ample clearance, perhaps even a 500 kg bomb is marginally doable. The weapon bays, as now scaled up to said 4*0.5 meters, are though likely not enough for a wide range of missiles. More likely a specialized stand off ground/antiship missile would need to be designed for them. Again probably under 500 kg in weight.

Still, even with just, say, 6 tons of internal fuel, I believe said UCAV should have something like 5000+ km ferry range. With a 1 ton weapon payload that would surely drop, but it still points out to 1500+ km combat radius in my opinion.
 

enroger

New Member
Registered Member
Okay, I've slapped together something real quick in KSP+FAR. Before you state the obvious, I know FAR aero model would be wildly inaccurate at high supersonic, I'm just trying to get an overall feel of the problem here, mostly I'm interested at what kind of lift/drag ratio I can get at what speed/altitude. So here is the thing:
ZTTL6RF

XQqwFBH
ZTTL6RF

XxX24OM

9IjbSnM

dry mass 3 tons, loaded 15 tons, aerozine50+NTO fuel, initial TWR 0.4, isp 334s.

Important thing is I got lift/drag 3.5 at mach 4 34km altitude, feels like this is the sweet spot if you are optimizing for range. Calculate range with Breguet Equation:
1200m/s * (L/d = 3.5) * (isp 334s) * ln(mass ratio = 4)= 1944km

This is just the powered flight range, the plane can still glide for quite a bit

EDIT Image link to imgur not working...
 
Last edited:

anzha

Junior Member
Registered Member
The images, which were published by Chinese state media during rehearsals for the 1 October parade in Beijing to mark the 70th anniversary of the founding of the People's Republic of China, showed two examples of the triangular-shaped UAV bearing serial numbers 21311 and 21312.

Five-digit serial numbers adhering to the format 21x1x indicate that the platforms bearing them, including some H-6M strategic bombers, are operated by the 10th Bomber Division (30th Air Regiment) within the Eastern Theatre Command, which faces Taiwan and Japan.

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enroger

New Member
Registered Member
Played around more with my virtual wz-8, released over eastern edge of Hainan island travel due west, it can reach Vietnam and Laos and perform a 2~3g 180 turn and return to Hainan with plenty of kinetic energy left (still mach 2 over Hainan, did some maneuvering to shed speed for landing).
If I let it go on a straight line all the way, it almost reaches coastline of India but not quite, that's 2000ish km.

My opinion is that it is definitely a usable spy system, range is a bit short though, if it were powered by ramjet like D-21 it could easily double the range. Rocket is a good enough stop gap measure before you have better stuff, not to mention cheaper. If it needs to recon high value targets deep in the west pacific you can justifiably use it as a one-time item and not worry about recovery.

Also the flexibility in speed and altitude is huge... It can cruise at mach 4 at 35km, or in a dash up to mach 6 at 40km. With specs like this it can probably enjoy invulnerability for quite a few years.

Still, I believe something with TBCC or RBCC must be in the work, obvious next step. Frankly I'm a little disappointed, wz-8 is usable but not as sexy....
 

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