Tiny vanes glued to planes promise big savings for US Air Force
32 comments
·February 2, 2025jmward01
Meanwhile they likely have hundreds or even thousands of lbs of dead equipment in them that accumulates as they are updated over the years. At least that is what happened to the P-3. Removing things is often a lot harder than adding them unfortunately.
crooked-v
Is that "dead equipment" as in "literally doesn't work", or is that "dead equipment" as in "nobody's used it in 35 years but one of the many edge cases involved in fighting a war will inevitably call for it"?
Jtsummers
A mix.
For the mechanical and hydraulic systems, it's certainly not dead though maybe underutilized or, as the mission has evolved, unnecessary. These aircraft get torn apart and rebuilt during depot maintenance every X flight hours or years. If those systems aren't working, they're fixed.
They also tear out old patches and replace them with new ones, and these days (this century, really) they don't bolt on patches which creates its own problems they use adhesives and they use modeling to try and reduce the patch size to its minimum. So you don't fly around with unnecessary patches on your airframe (here I'm assuming you're at one of the competent depots, not like NG who left a plug in a fuel line and totaled the plane, fortunately it was able to land safely).
But for electronic equipment and some stations and fixtures it may be deadweight or excessive weight.
Electronic equipment may not get a modernization effort for decades. And depending on who wins that contract (who am I kidding, if it's one of the main five primes you're fucked) it's likely the effort will fail 2-3 times before it succeeds. Imagine flying with a radio built in 1980. Everything in it except maybe the power supply and of course the antenna can fit inside a cellphone today. That's a lot of weight that could be removed, but it's not deadweight. It's still in use.
But you also find things like stations and even racks (in some of the heavies) to hold LRUs or control panels and screens that were designed back when you needed 20 LRUs to do what one can now, or a huge wiring harness that is now a keyboard, mouse, and workstation. These stations and racks don't always get cleaned out like they should and would be dead weight.
jmward01
Yes and no. It is often just dead equipment. But sometimes it could still be turned on but there is no purpose for it anymore. The P-3 has been used for a -lot- of things over the years. Beyond that it is just heavy old versions of things that could easily have been lighter and required far less power. Using a 60 year old design for a replaceable part is an expensive luxury only the military can afford. If we had modernized the avionics and the main load center on that plane it probably would have save 10-15k lbs without even changing the engines or airframe.
dghlsakjg
Slap an inop tag on it and keep moving.
titanomachy
> 1% reduction in fuel consumption... will save $14 million dollars per year
Implying that the US air force spends $1.4 billion a year on fuel just for the C-17.
bunabhucan
Some of the fuel comes from mid-air refueling.
The USAF used the baseline fuel price in earlier studies to determine if it made economic sense to re-engine the B-52.
datadrivenangel
Sounds not unlikely...
jlkuester7
> Just remember that the brake pads on your car are stuck on with glue next time you tap the pedal.
Unrelated to the article's point, but what? Maybe the layers of the pad itself are glued together, but no brake pads I have every changed have been stuck to the car with glue in any way. (They are held in place with metal brackets which allow them to slide along a small track when compressed by the brake pistons....)
andrewflnr
I assume they're talking about the bond between the metal frame that interacts with the brackets and the actual pad material itself, made of sintered metal or ceramic or something.
ferongr
Pads were the friction material is solely using glue to adhere to the backing plate are generally either very cheap aftermarket replacements or the OEM cheapening out.
andrewflnr
What are they supposed to do? Can you weld them on somehow?
dghlsakjg
I think they mean the interface between the wear material and the backing.
I'm not entirely sure that it is just glue, but the flip side is that the wear material is, well, wear material that wears away over time, so mechanical attachment needs to not interfere with that.
Plus, if the wear material did come loose from the backing, it would likely make a bit of a racket rattling around (like a brake pad without its anti-rattle clip), but it doesn't really have anywhere to go since it is surrounded by caliper and rotor, and would probably work just fine since the backing is there to spread out the force from the piston evenly along the wear material. That force would still get spread out, the wear material might just shift a few mm.
bombcar
Glue can be quite strong.
I remember hearing that the 26 ton ceiling collapse on the big dig https://en.wikipedia.org/wiki/Big_Dig_ceiling_collapse was because they used the wrong glue (epoxy, but basically the same thing).
null
m3kw9
Why not on commercial aircraft?
Havoc
1 percent gain from that seems wild.
I wonder how they arrived at this. Seems like it would be ideal for some sort of evolutionarily algo perhaps
calmbonsai
These are simply vortex generators when have been a post-production modification in many models of GA aircraft (most notably Rutan canard models) for decades.
They induce turbulent flow (vortices) which, under the correct circumstances, can actually benefit range, albeit, at the cost of overall lift efficiency across the originally designed flight envelope.
To use Randall Munroe's "Thing Explainer" vocabulary, they enable the aircraft to "go slower better", but at the expense of making it "go faster worse".
CrimsonCape
The concept of laminar flow applied to aircraft seems like a little-explored topic. Clearly there is benefit as the article demonstrates.
Imagine these small "microvanes" evolved into 3D printed laminar-flow structures.
For example, think a honeycomb pattern extruded into hundreds of small tubes. Or, as another example, aircraft with "fur"...imagine the leading edge of a wing covered in fine stiff bristles. Literally "combing" the air as it passes over the wing.
master_crab
Laminar flow over aircraft has been studied for decades. Hell the mustang used a NACA airfoil specifically designed to maximize laminar flow.
JumpCrisscross
> laminar flow applied to aircraft seems like a little-explored topic
You’re sort of describing the fundamental gestalt of an aircraft: lift. Aerospace engineers (hello!) spend a lot of time on laminar flow about the wing because when it stops being laminar the flow separates and then the plane goes down more.
peterdsharpe
> when it stops being laminar the flow separates
Not true, laminar/turbulent and attached/separated are independent descriptors. Flow can be laminar+attached, laminar+separated (e.g., laminar separation bubbles), turbulent+attached (e.g., the majority of boundary layers on large aircraft), or turbulent+separated.
Onavo
Yes but pure laminar flow wings have undesirable stall characteristics.
JumpCrisscross
> pure laminar flow wings have undesirable stall characteristics
Sure. My point is that if there's one thing aerospace engineers are constantly thinking about, it's fluid flow. Including, critically, when it's laminar and when it's not.
Onavo
Is this for laminar flow or is this a vortex generator?
sandworm101
Ya, this is about triggering vortexes in order to keep the flow stable and near the skin. It isn't about laminar flow which, at the back end of an airplane, isn't such an advantage.
Perhaps worth nothing that the last C-17 produced was in 2015, after which the closed the Long Beach plant:
* https://en.wikipedia.org/wiki/Boeing_C-17_Globemaster_III