Tesla truck, sharp edges and aero

[Cold Fussion]

Didn't the Iraqiees take one down with a heat seaking missile?

Not a B2, no. Several F117’s have been lost in combat iirc.

Famously a F117 was shot down during the Balkans wars but from memory they were very lucky to actually shoot one down because they predicted its location based off previous bombing runs.

[pb6797]

Some fighter Jets have sharp edges..

https://upload.wikimedia.org/wikipedia/ ... _Front.jpg

That's to reduce the radar signature prior to computer designed radar avoidance, not for good aero. It's also a bomber not a fighter, and it's been retired ever since for a better aero approach, f22 I think

Compare the thrust to top speed of this jet with other stealth fighter jets. before u say its draggy.

I think they also filtered the engine's output through a grill to minimise the Infrared Signature, which also limited the thrust available even further.

[Tommy Cookers]

well I thought the CFD by alelanza was interesting
rather like the 60s Le Mans-style 'ducktails' that reduced drag (and lift) but exasperatingly became called spoilers

and btw ...

The reason the F117 has flat surfaces is due to the lack of computing power at The time it was being designed to calculate a radar reflecting shape with curved surfaces.
The B2 was the result of much more computing power being available and it has the radar cross section of a pigeon as a result. The only reason the B2 needs computers to fly it is due to the flying wing design being inherently unstable, it has nothing to do with the stealth properties.

the calculations for 'radar defeating' shapes were freely published by a USSR scientist
before that ? the SR-71 had shape and coating for this - but eg was picked up by UK radar flying to the Farnborough show
flat surfaces are beatable by '3d' radars eg the Czech one that Russians took from Kosovo to prevent the US getting it

early highly unstable planes flew by having suitable analogue control/stabilisation systems
eg the Rockwell X-31 HIMAT evaluated both analogue and digital - digital was at that time inferior
digital is self-maintaining and now fast enough
aerodynamic instability means less energy loss in manoeuvre control and ride control and (importantly) for trim
but afaik may demand greater structural stiffness (higher loadpath natural frequencies) ie CFC structures

[bill shoe]

American full-size pickups and SUV's get their top dollar because (among other reasons) they are the only remaining bastion of body-on-frame architecture and the excellent Ride/NVH isolation that comes with it.

Aren't they classed as trucks and thus not required to meet the safety and emissions rules applying to cars? Hence they can be cheaper to make and thus can be sold at an attractive price. Of course the big pickups are very macho which appeals to many.

You can get excellent ride/NVH from a unibody too - the mechanicals are mounted via bushed subframes after all so there is no difference in the path from road to occupant in either type. As shown by the likes of Jaguar etc.

Pickups are classed as light trucks. They have to meet all the safety requirements of cars. In real-world accidents with other vehicles, pickups are safer than cars due to higher weight and higher height/CG. Rollover risk of higher CG is largely gone due to electronic controls (stability control, rollover control).

GHG Emissions in the U.S. are different for cars vs trucks, and trucks have it easier (generally speaking). This is why many car-type unibody vehicles are trying to technically classify themselves as trucks.

Any type of vehicle architecture can be executed well or badly. But if you take an experienced vehicle evaluator, force him to drink a 6-pack, beat him soundly about the head with a large club, blindfold him, stick him in a random car or light-truck, and tell him to drive, I guarantee they will determine in a few seconds if they are driving a body-on-frame or unibody. The difference is that fundamental.

The difference comes from the fact that the full-frame's natural freq (6-10 hz) is lower than the suspension secondary frequency (10-15 hz), therefore the full-frame is an extremely effective barrier against road-induced Ride/Noise getting into the body. Unibody subframes with bushings help but they do not have this fundamental quality that full-frame vehicles do.

After all that hand-waving, I would love to have a Jag!

[alelanza]

Some interesting initial CFD on this, a ton better than I expected, almost hard to believe

https://www.goengineer.com/2019/11/27/c ... imulation/

[foxmulder_ms]

I love it and ordered one. Stainless steel was too good to pass Love it!!

[cplchanb]

Some interesting initial CFD on this, a ton better than I expected, almost hard to believe

https://www.goengineer.com/2019/11/27/c ... imulation/

wait and see until the real production version is released. So many of this truck is not up to regulation, which includes the potentially sharp edges. Not to mention mirrors are still missing.

[Giblet]

Mirrors can be literally slapped on at the last minute, and they are not required if there are cameras in place in some countries.

The edges are sharper than typically rounded ones, but they are not actually sharp.

[Cold Fussion]

If you don't care about aerodynamics at all then it can be a last second job.

[e36jon]

If you don't care about aerodynamics at all then it can be a last second job.

When I first read "Aerodynamics of Road Vehicles" by Hucho I was surprised to learn that aero development fell into two broad categories: One category is starting the vehicle form development process from a aero perspective and then adding the details needed to finish it as a complete car at the end of the process. The second category was starting from a styling POV and then adding aero at the end. The two paths converged, surprisingly, in overall drag coefficients that were basically the same. So, 'a last second job' doesn't necessarily mean you don't care about aero...

[strad]

Wish I had saved the online Hot Rod magazine article I received. I can't remember the exact terms but the flow was way better than the models and experts expected.

[J.A.W.]

Panzer truck?

[63l8qrrfy6]

the calculations for 'radar defeating' shapes were freely published by a USSR scientist
before that ? the SR-71 had shape and coating for this - but eg was picked up by UK radar flying to the Farnborough show
flat surfaces are beatable by '3d' radars eg the Czech one that Russians took from Kosovo to prevent the US getting it

I remember reading this in Ben Rich's Skunkworks - I think USSR believed that the calculations were so computationally demanding that they were impractical and allowed the papers to be published.

Lockheed Martin obviously took a different view.

On topic - functional or not that is objectively a hideous machine