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Sukhoi S-70 Okhotnik UAV revealed

TomcatViP

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Supersonic dash: in order to keep being relevant with a supercruising fighter...

Imagine your wife with a Vuitton hand bag that keep slipping from her arm... She'll ask you to sent it back and get the 30$ model right after a couple of days.

Wait... ::)
 

Trident

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My latest iteration, with some speculation as to the ultimate configuration of the nozzle & aft deck (to represent a possible production variant, sans the lumps and bumps). Looking at the newest photos & re-examining the older ones, the wing tips apparently have a F-117-like crop that is not visible in the outlines painted onto Su-57 #053 (image resolution too low in the tail fin silhouettes, edge pixelation too coarse in the belly/back digital camo).

EDIT: the sweep angles seem a bit too steep as drawn, but the relationships look right to me.
 

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stealthflanker

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the size.. if accurate can be used to determine what kind of power aperture achievable for hypothetical radar.

Maybe this one can hold more promise for the leading edge mounted L-band aperture.
 

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I have feeling that nose radar might be version of side-looking N036 array. Makes sence from unification and price points.
 

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One could fit a half decent 400 by 800 mm aperture radar in that nosecone. So it could be closer to a light fighter radar in capability.
 

GARGEAN

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Well, side array of N036 is not too small either. Pretty well cam fit into "light fighter" category, esp considering possibility of use of GaN TRMs.
 

Trident

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Recently a near-perfect beam shot of Su-57 #053 at near-zero elevation angle was published, so I decided to check the planform of my modified Paralay-drawing against it. Low resolution remains a problem, so it's impossible to nail down the precise sweep angles to within less than 3° or so, but it's definitely in the right ball park IMHO.
 

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TomcatViP

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It's a remarkable effort for sure but I won't have much trust in a cutout silhouette wire taped on a canted surface to be hand sprayed with paint...
 

Trident

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It's a valid objection, which is why I made a point of comparing the shape from the tail fin and the belly digital silhouette and noting that they match very well. Apparently this paint job was no quick improvisation, somebody took care to faithfully reproduce a specific outline in both places and at vastly different scales.
 

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The Air Cosmos article by Piotr Butowski seems to indicate a maximum speed of 1,400 km/h at altitude, or about M=1.3. Personally I'm rather skeptical of this figure, and in any case I don't see what significant tactical utility this would even bring. Perhaps the current nozzle has TVC in order to provide adequate directional control?
 

flateric

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That's where supersonic speed allegation originated from
https://tvzvezda.ru/news/opk/content/201803291205-2u4j.htm

I doubt that we can afford development of two various heavy unmanned platforms at the same time for the same purpose, one subsonic and other supersonic, ergo...
 

Austin

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Steven said:
The Air Cosmos article by Piotr Butowski seems to indicate a maximum speed of 1,400 km/h at altitude, or about M=1.3. Personally I'm rather skeptical of this figure, and in any case I don't see what significant tactical utility this would even bring. Perhaps the current nozzle has TVC in order to provide adequate directional control?
Consdering 117S can do a 14-14.5 T in AB mode cant it do Supersonic for short duration with AB mode on at low altitude ?
 

icyplanetnhc

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Austin said:
Steven said:
The Air Cosmos article by Piotr Butowski seems to indicate a maximum speed of 1,400 km/h at altitude, or about M=1.3. Personally I'm rather skeptical of this figure, and in any case I don't see what significant tactical utility this would even bring. Perhaps the current nozzle has TVC in order to provide adequate directional control?
Consdering 117S can do a 14-14.5 T in AB mode cant it do Supersonic for short duration with AB mode on at low altitude ?
It's not just a matter of thrust, but also pitch authority as the neutral point moves aft, as well as decreasing directional stability (flying wing configurations are already challenged in both arenas).
 

Sundog

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Steven said:
It's not just a matter of thrust, but also pitch authority as the neutral point moves aft, as well as decreasing directional stability (flying wing configurations are already challenged in both arenas).
I'm sure the AB is just for acceleration, not supersonic capability, due to stability and control reasons as you noted. Of course, it's most likely being used because it's readily available. If it's designed to be an actual A2A combat maneuvering vehicle, then the AB would be great to maintain energy while maneuvering. But it would definitely be a poor design for supersonic performance.
 

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Can they use the TVC capability to over come issue for supersonic flying wing design ?
 

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Its got too much wing for a low level supersonic design IMHO.
 

icyplanetnhc

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Austin said:
Can they use the TVC capability to over come issue for supersonic flying wing design ?
But why though? Just because you can, doesn't mean that a flying wing of the current configuration is ideal for supersonic flight. I don't see what kind of favorable design tradeoffs would result from that.
 

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Hello!

Comparison: Su-57 - Okhotnik - Man (~ 1.80 m).

To make this comparison, I have assumed that both devices have the same wheel of the main landing gear.

Yes, the Okhotnik is a big machine... something like "the father of all UCAVs !!

Best wishes
 

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quellish

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PaulMM (Overscan) said:
Its got too much wing for a low level supersonic design IMHO.
Also too much landing gear. It sure looks like they built it to carry a lot of weight.
 

malipa

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To be honest I think this aircraft might have a supersonic dash capability of Mach 1.2, it simply has way too much wing to be a true supersonic aircraft. You need a heck of a lot of thrust and a very thin wing to get something like that supersonic. I think the nozzle was simply a way to decrease the amount of research and development costs, since the Russian government has money problems a the moment.
 

Austin

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Steven said:
Austin said:
Can they use the TVC capability to over come issue for supersonic flying wing design ?
But why though? Just because you can, doesn't mean that a flying wing of the current configuration is ideal for supersonic flight. I don't see what kind of favorable design tradeoffs would result from that.
Agree , Flying wing is not the sort of design where you can sustain a supersonic speed.

Since they mention supersonic at Low Altitude which is doubtful , What about high altitude where the air may be thinner can it go supersonic ?
 

TomcatViP

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Austin said:
Steven said:
Austin said:
Can they use the TVC capability to over come issue for supersonic flying wing design ?
But why though? Just because you can, doesn't mean that a flying wing of the current configuration is ideal for supersonic flight. I don't see what kind of favorable design tradeoffs would result from that.
Agree , Flying wing is not the sort of design where you can sustain a supersonic speed.

Since they mention supersonic at Low Altitude which is doubtful , What about high altitude where the air may be thinner can it go supersonic ?
You know, they are not NACA 4 digit series airfoils. Most Flying wing today have a supercritical airfoil, meaning that they are transonic per essence. I won't be surprised to clock a low flying B-2 at Mach 0.9++ ;)
 

AeroFranz

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I would. M0.9 is pretty far into the transonic drag rise.
 

TomcatViP

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Not to be pedantic :

"Korn" equation*:

MDD +CL/10+t/c= κ A

where κ A is an airfoil technology factor. The airfoil technology factor has a value of 0.87 for an
NACA 6-series airfoil section, and a value of 0.95 for a supercritical section. MDD is the drag
divergence Mach number, CL is the lift coefficient, and t/c is the airfoil thickness to chord ratio. This
relation provides a simple means of estimating the possible combination of Mach, lift and thickness
that can be obtained using modern airfoil design, and variations of it have been shown graphically
by many authors, where the scales are often left off when presented for the public by aircraft
companies. Note that the Korn equation is sensitive to the value of the technology factor.
So if t/c increases with Cl (typical in the case of a flying wing), MDD increases (at equal technology level)...

Once again,

TomcatViP said:
I won't be surprised to clock a low flying B-2 at Mach 0.9++ ;)

*CL seen as the full wing Coefficient and not the one for airfoil only

Source:
http://www.dept.aoe.vt.edu/~mason/Mason_f/ConfigAeroTransonics.pdf
 

AeroFranz

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I'd be wary of applying the Korn equation outside of it's scope. I don't know the exact genesis of it, but it looks like it was derived from regression of data most likely obtained from supercritical airfoils applied to - I'm guessing - airliners and trainers. Did they have data points in the vicinity of M0.9? I wouldn't know.
A B-2 operates at lower CL than a tailed counterpart (lower wingloading), so that undoubtedly helps. It also has more sweep, another good thing.
But there's other things that make this a weird case, like the fact that your wing is providing the lift and the stability at the same time, so the allowed domain of spanwise CLs is going to be more constrained compared to, say, an airliner. Also at low altitude you get things like gusts, so i would keep a respectful margin on MDD. Incidentally, flying at low altitude at M0.9 in a low wingloading, mid-sweep vehicle must be an interesting experience! :eek:
But the main thing is, If it were me, i'd keep the MDD reasonable and make nice fat airfoils to get lots of volume for fuel/systems/weapons and deep (= lightweight) structures. That's got to be more useful than gaining .05M at low level.
 

TomcatViP

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It's not an equation to use for research. It's a tool to estimate quickly a range of value in an existing knowledge database of airfoils.

Here, you would read it like that: If there is an existing airfoils suitable for wing-body airframe at Mach number M, there is a similar airfoils usable for a flying wing that will either have the same Cl with a M- lower critical number (least probable case) or one with a superior lift coefficient and higher M (M+)*


*[size=10pt]Hence my little line about the 0.9++ B2[/size]
 

AeroFranz

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I think we can agree that the physics dictate that if you have more sweep, lower CL, thinner airfoils (supercritical in particular), you're going to fly faster before hitting MDD. The B-2 does well on several of those accounts, others like t/c, i don't know. I'd just be wary of applying any equation obtained through regression for cases that may be outside of the database used.

But generally speaking, an axiom in aircraft design is that you don't design in a capability that is not useful if it comes at the cost of something else more important. Unless the customer determines that they need the capability, it's much better to barely meet the requirements and get the smallest/cheapest aircraft you can. Maybe someone has better knowledge of what the thought at the time was regarding very high speed terrain following.
 

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I've been liking this thread, along with all the analysis. But a question keeps coming to mind for me.

Why has it suddenly been revealed ? ??? I would have thought the Russians would have it wrapped pretty good
 

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quellish said:
PaulMM (Overscan) said:
Its got too much wing for a low level supersonic design IMHO.
Also too much landing gear. It sure looks like they built it to carry a lot of weight.
Could it be that they just reused an existing landing gear for the prototype for economic reasons, but the production one could be different/lighter?
 

GARGEAN

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kitnut617 said:
I've been liking this thread, along with all the analysis. But a question keeps coming to mind for me.

Why has it suddenly been revealed ? ??? I would have thought the Russians would have it wrapped pretty good
It would be known since first flight anyways(which is close). Spotters don't sleep.
 

flateric

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kitnut617 said:
Why has it suddenly been revealed ? ??? I would have thought the Russians would have it wrapped pretty good
Leak was unplanned. I wouldn't like to be in position of guys who posted pics on the web.
GARGEAN said:
It would be known since first flight anyways(which is close).
It depends. Orion, Altair, Corsair, number of Army URAVs and many other stuff was flying years before any photos were public, many stuff is still under wraps - even been shoot by spotters, who then decided that 5 minute glory on the web doesn't deserve possible and real problems.
S-70 maiden flight =/= automatic official declassification with press-releases and photos, neither spotters around, especially in her current location.
 

malipa

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TomcatViP said:
Not to be pedantic :

"Korn" equation*:

MDD +CL/10+t/c= κ A

where κ A is an airfoil technology factor. The airfoil technology factor has a value of 0.87 for an
NACA 6-series airfoil section, and a value of 0.95 for a supercritical section. MDD is the drag
divergence Mach number, CL is the lift coefficient, and t/c is the airfoil thickness to chord ratio. This
relation provides a simple means of estimating the possible combination of Mach, lift and thickness
that can be obtained using modern airfoil design, and variations of it have been shown graphically
by many authors, where the scales are often left off when presented for the public by aircraft
companies. Note that the Korn equation is sensitive to the value of the technology factor.
So if t/c increases with Cl (typical in the case of a flying wing), MDD increases (at equal technology level)...

Once again,

TomcatViP said:
I won't be surprised to clock a low flying B-2 at Mach 0.9++ ;)

*CL seen as the full wing Coefficient and not the one for airfoil only

Source:
http://www.dept.aoe.vt.edu/~mason/Mason_f/ConfigAeroTransonics.pdf
Respectfully I have some comment's here I'm afraid.

In my first years project at the TU Delft of Aerospace engineering we did a design for a flying wing on Mars. And I learned the following basics: The lift coefficient on such a wing is not to high and has a value of about 0.5, not too high to insure that the stability of the flying wing behaves in a relaxed way, not with very steep curves and thus big zero values (locus related). The aircraft has a huge area so it's fine do make this choice. And because you're lift is not very high you can give the wing a bigger thickness value without the huge drag penalty, which is very nice for long range since a big internal volume is good for your fuel capacity. Furthermore the B-2 uses a fuel management system to influence it's stability and has a rather big value for the thickness at the end of the wing, so it can shift it's center of mass further aft. The thickness is also needed to allow bigger masses to be left at the end of the wing, because the wing is stiffer. And this is pretty visible in the B-2 design, it has a pretty consistent chord and thickness over the entire wing.

This rather thick wing does result in a lot of drag and a rather bumpy ride on low altitude. That is the nature of a thick wing and having a very low wing load. If you look at the TSR-2, that has a very high wing load and a very thin wing, and remember that that aircraft was built to surpass the trans sonic area at low altitude.


Also the airfoil will likely not be a standard super critical airfoil because of stability reasons, I think the K value in the Korn equation will be lower than 0.95.

And if I also look at the maximum speed of the aircraft at altitude, begin 0.95 at 40.000 feet, I dare to assume that that is far beyond the MDD.

So concluding: The Korn equation-> having the constant being 0.92, the thickness to chord ratio being between 0.05 and 0.1, and the CL being around 0.5, the MDD would become around 0.85 in the best scenario. And at low altitude a 0.9 flight would not fit within the flight envelop.

"So if t/c increases with Cl (typical in the case of a flying wing), MDD increases (at equal technology level)..." If I read this, and I might have misunderstood it, but the MDD would then have to decrease and not increase if the T/C and CL increases, since kA is a constant.


And if I would use this information to analyse the S-70, the same would hold. The aircraft would be able to flight at high trans sonic speeds, and cruise at about the same speed as the B-2. But it would not be likely to surpass this. The nozzle of the aircraft would suggest such a thing, but I think this can be explained in two different ways.
- The nozzle might be enable TVC, using brute force to solve the stability issues.
- The nozzle has already been developed for the T-50, this is a way to save a lot of money. Don't forget that the X-47B reused a whole lot of other aircraft parts such as landing gear, to decrease the development costs. And also don't forget that the Russian government doesn't have lot of money to spend, they dramatically increased retirement age which caused a whole lot of outrage, to save money. And also this aircraft can be designed as a more prestige like project. So such a money saver at least sounds plausible.
 

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quellish said:
PaulMM (Overscan) said:
Its got too much wing for a low level supersonic design IMHO.
Also too much landing gear. It sure looks like they built it to carry a lot of weight.
As i have previously posted, landing gear is from T-50 and it will get its own landing gear from the next frame onwards.
 

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