this post was submitted on 05 Sep 2023
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In Ukraine, a drone with a jet engine and a flight range of 400 kilometers has been developed (odessa-journal.com)
submitted 1 year ago* (last edited 1 year ago) by Wilshire@lemm.ee to c/ukraine@sopuli.xyz
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[–] Hopfgeist@feddit.de 16 points 1 year ago (2 children)

I wonder what the design decision was for the forward-swept wings. These typically decrease lateral stability and increase structural weight, because they require substantially higher stiffness for flutter-resistance compared to straight or rear-swept wings. Maybe so the main wing spar can be further aft to have a larger contiguous payload bay. The HansaJet had forward-swept wings for a similar reason (no main spar in the cabin).

[–] GiuseppeAndTheYeti@midwest.social 4 points 1 year ago (1 children)

I would think it's got to do with spanwise flow. The forward swept design brings the spanwise flow toward the fuselage and allows for more effective control of the ailerons when traveling at transonic speeds like can be expected from a "drone/missile/UAV" like this.

It also allows for a reduction in vortices formed by the wingtip which would increase drag and decrease efficiency. That means you can get away with a smaller wing, decreasing weight and either increasing your payload or maximum range.

[–] Hopfgeist@feddit.de 3 points 1 year ago (1 children)

If it were beneficial in total, most transonic planes would have it. The only aerodynamic advantage over backward swept wings is higher manoeuvrability, which isn't a priority here. This isn't a dogfighter. My money is still on better payload distribution.

more effective control of the ailerons

Not sure what that means. I don't think agility is a priority with a jet-powered drone. Or benign stall characteristics.

reduction in vortices formed by the wingtip which would increase drag and decrease efficiency

That is negligible. We know how to reduce wingtip vortices, and reverse sweep is not the answer. Raked wingtips as used on the 787 and the larger-wing versions of the 777 and the 777X are optimal for transonic flight. Blended winglets are a close second, as used on the A350 and A330neo. Again, not forward sweep.

This thing also does not look very refined aerodynamically, and there are many more things that could be done to reduce drag that are much cheaper. Wing-body fairings come to mind to reduce interference drag, or winglets if you really want to go there. This has all the looks of "Eh. Good enough. Send it!", which makes sense given the urgency.

[–] Ulara@sopuli.xyz 1 points 1 year ago (1 children)

I think they don't have at their disposal a proper aerodynamic tube. Perhaps you would kindly recommend some software to model the aerodynamic properties?

[–] Hopfgeist@feddit.de 2 points 1 year ago

That's the point. This is not a very refined design, it is a quick-and-dirty, "good enough" approach to get it out of the door as quickly as possible while still fulfilling the requirements. Which is why I found it surprising that forward sweep was deemed the best option, despite its aerodynamic and structural challenges (which usually outweigh any benefits). And as I said, fuel efficiency was not foremost on the designers' minds. Case in point: small turbojets are notoriously inefficient (only pulsejets and rockets are worse), and many small details could be improved cheaply. But having a large unobstructed payload bay is a very good reason for forward-swept wings on such a small design and can greatly simplify operation. I will not recommend any computational fluid dynamics package, because it takes many years of study and experience to apply it to real-world problems meaningfully. And if the design team includes aerodynamicists, they will know what software to use anyway, and don't need my recommendation. Surprisingly, if you have good data on the airfoil cross-section performance, X-Plane is not the worst tool to get a good idea of performance and stability. It was used for Solar Impulse in that way (also for pilot training).

[–] theodewere@kbin.social 2 points 1 year ago (1 children)

the main wing spar can be further aft to have a larger contiguous payload bay

and maybe so it can carry all the heavy, rude stuff right up front, with all the control in the rear..

[–] Hopfgeist@feddit.de 1 points 1 year ago* (last edited 1 year ago)

I think this is mostly a reconnaissance and electronic countermeasures drone, with refined, rather than rude stuff.

[–] Jaysyn@kbin.social 11 points 1 year ago (1 children)

I hope these drones fill the skies in Moscow soon.

[–] Hopfgeist@feddit.de 2 points 1 year ago

It's not a cruise missile. It's ECM and reconnaissance/intelligence gathering.

[–] Ph0mX@kbin.social 5 points 1 year ago (1 children)

Isn’t this the drone in the pics? https://www.ukrspecexport.com/uploads/redactor/6%20USE_UMEX_Topaz_PRINT.pdf

[–] agent_flounder@lemmy.one 2 points 1 year ago

As far as I can tell, yes.

[–] RandomStickman@kbin.social 4 points 1 year ago (1 children)

With all the confusion I think it's time to bring back the term UAV

[–] Zorque@kbin.social 3 points 1 year ago

We sent them all through the Stargate, there aren't any more.

[–] happyhippo@feddit.it 3 points 1 year ago

The cabin is inside a van folks (just before anyone asks)

The photo sequence makes it funny tho 😂