Why aren’t plane front sections shaped more like a bullet?

[JHZR2]

…. Yeah I know there are flat nose, hollow point, whatever bullets…

In all my flying which is a reasonable amount (halfway to million miler status on American, lots of flying on Delta too), I guess I never really looked at the “nose” of the aircraft I’ve flown on.

There was a bit of holdup on the tarmac on my last flight, and I noticed this:

I had always thought (or not looked close enough) that the nose of airliners like the 737 was symmetric and fully round to maximize aerodynamics. I was surprised to see how much of a notch there is.

And then… zooming in…

Really??!? OK… wow. Even my 1993 Mercedes hides the windshield wipers out of the way. Sure, an airliner doesn’t have a cowl, but I’m a little surprised the wipers look so… un-aerodynamic…

I guess maybe all these things amount to a rounding error when you consider the sheer size and mass of an airliner. And as I noted, I just was never very observant of any of this. But I’m still a bit surprised, especially if wipers out in the wind at Mach 0.85 or wherever the 737-800max flies at.

So, time for schooling. @Astro14 & @Cujet … obviously it is established and works…. But at minimum, don’t wipers get a bit shaky and noisy (?) when flying, given how they are parked like that? Or is there another reason why it’s irrelevant when flying in thin air a few miles up?

And are other airliners more of a symmetrical almost spherical front?

Dumb questions… sorry…

 

[MRC01]

If you want to go really fast, the nose cone looks like this

 

[Kira]

You gotta think aircraft designers have volumes of wind tunnel experiment data in the books; so I'll go with your guess that differences in air resistance caused by varying 'notches' are small. The 'notch' would be called the stop if dogs flew, by the way.

I can't recall the flushness of the SST's windshield. The flusher a windshield is, the larger the piece of glass would have to be, no?
Fighter jet pilots need visibility so that explains those prominent bubble canopies.
Maybe cameras will soon make some windshields obsolete?

+1 on the windshield wipers. Maybe there's no other (better?) way to do it.

 

[mk378]

Fully round is important for a bullet since they spin in flight. Not so much of a concern for a vehicle.

The nose of an airliner contains a lot of stuff including RADAR antennas for weather and collision avoidance. The need to fit those inside constrains the external shape.

 

[JHZR2]

Fully round is important for a bullet since they spin in flight. Not so much of a concern for a vehicle.

The nose of an airliner contains a lot of stuff including RADAR antennas for weather and collision avoidance. The need to fit those inside constrains the external shape.

That’s true. And of course since there are wings necessary for lift, it’s got plenty of other forward-facing spots to affect airflow. The notch up for the cockpit is small compared to others.

Making it more round in front might affect the “depth” of the nose cone, but not necessarily front-facing area to radiate from. Perhaps it’s not healthy for pilots to sit on top of it, so the cockpit being further back is an OS&H design too….

 

[BMWTurboDzl]

That’s true. And of course since there are wings necessary for lift, it’s got plenty of other forward-facing spots to affect airflow. The notch up for the cockpit is small compared to others.

Making it more round in front might affect the “depth” of the nose cone, but not necessarily front-facing area to radiate from. Perhaps it’s not healthy for pilots to sit on top of it, so the cockpit being further back is an OS&H design too….

Notice the diffuser looking fins at the seam between the nose cone and the airframe? I wonder if they create a low pressure area at the cockpit?

 

[dwendt44]

I noticed the same thing with submarines; a more pointed nose would
cut through the air/water with a bit less resistance you'd think.

 

[kschachn]

I was taught in college a pointed nose is used because of the creation of a supersonic shockwave above the speed of sound. Below that a rounded nose is preferable.

 

[Astro14]

First, your picture is of an antique. The 737 first flew in 1967. It’s noisy, slow, and antiquated. That said:

Do you want your pilot looking through the curved glass of a bullet when trying to land?

Or flat, distortion-free glass?

The shape is a compromise, but flat glass is an important element for flying the plane, I have to see clearly. In addition to visual clarity, flat glass is stronger, easier to manufacture, easier to replace, easier to heat. And windows are heated for structural/impact reasons.

The wipers? They’re hidden in your Mercedes to lower noise, the difference in drag is imperceptible. At Mach .80, noise comes from everything, and the wipers make little to no difference in total noise. The make little to no difference in drag, either. So, they’re positioned to be most effective in clearing glass.

 

[doitmyself]

The B 29's had that rounded nose: ....................Boing 787 is more round

Wikipedia identifies this as the stepless cockpit: https://en.wikipedia.org/wiki/Stepless_cockpit

Interesting stuff. Learn something new every day here.

 

[JimPghPA]

Notice the diffuser looking fins at the seam between the nose cone and the airframe? I wonder if they create a low pressure area at the cockpit?

I think those are to make the airflow in streams with less left and right turbulence. Probably a decent drag reduction and maybe even less noise in the cockpit.

 

[billt460]

I don't know if this is true or not. But I heard the rejection rate for molded Lexan fighter canopies is extremely high. This is due to the fact they have to have all but perfect optical clarity. The slightest optical flaw and they are rejected. Which accounts for the ridiculously high replacement cost.

 

[vavavroom]

An egg-shaped nose is already very aerodynamic. You don't even need a pointy/sharp nose for supersonic flight, it's just that a pointy nose helps minimize the effects of the supersonic shockwave has on drag. For subsonic planes, a pointy nosecone would not offer a whole lot of benefits but more drawbacks such as a decreased field of view for the pilot but may necessitate complicated features like a retractable droop nose. The Space Shuttle, a very fast vehicle over 17,000mph during reentry, had a blunt nose, probably because a blunt nose gets hot more evenly over a larger area than a pointy nose which will get extremely hot over a very small area. The Concorde's nose reached over 350°F and the SR-71's nose reached 800°F.

 

[RooflessVW]

I'd be willing to bet that there is a low pressure area where the wipers are. At 600mph the air stream probably goes right over.

 

[JHZR2]

The B 29's had that rounded nose: ....................Boing 787 is more round
View attachment 110974View attachment 110979

Wikipedia identifies this as the stepless cockpit: https://en.wikipedia.org/wiki/Stepless_cockpit

Interesting stuff. Learn something new every day here.

Speaking of…. Second leg of my trip was on a 787.

Much smoother and more the vertical wiper orientation.

First, your picture is of an antique. The 737 first flew in 1967. It’s noisy, slow, and antiquated. That said:

Do you want your pilot looking through the curved glass of a bullet when trying to land?

Or flat, distortion-free glass?

The shape is a compromise, but flat glass is an important element for flying the plane, I have to see clearly. In addition to visual clarity, flat glass is stronger, easier to manufacture, easier to replace, easier to heat. And windows are heated for structural/impact reasons.

The wipers? They’re hidden in your Mercedes to lower noise, the difference in drag is imperceptible. At Mach .80, noise comes from everything, and the wipers make little to no difference in total noise. The make little to no difference in drag, either. So, they’re positioned to be most effective in clearing glass.

Thanks. Yeah the issue of vibrating/noisy wipers making noise wasn’t intended to be a goofball thing - both the step up and the location was just something I never spent any thought or observation on. I’d think that at Mach .80 anything that can add to wind noise does… and something feet from your face might be more obvious. Thus the query.

While I get it that a 737 is an older plane, they were pretty smart, and perhaps had more intuition back then. I can’t imagine the design was because of “style”….

The economics and visibility is an interesting point. I’d suspect they could have figured out how to resolve some of that, if nothing else than like the B-29 type solution if need be.

Is the radar location that was mentioned before a big consideration? I’d suspect the further away/behind that you can sit the better… of course other radiation sources is an issue too I guess….

Thanks!

 

[Astro14]

Radar location isn’t a big consideration, it’s in front of a pressure bulkhead, a Faraday cage, basically.

Remember that the 737 was a cheap, short range jet. So, inexpensive manufacturing was key. Aerodynamics mattered less than low cost.

The 787 is incredibly efficient, very long range, so drag matters, and it’s expensive to make, so, you see much better aerodynamic design.

 

[billt460]

Didn't Lear Jets use compressed air off the engines to blow the windshields clear?

 

[E365]

Related: The newer 737s added a row of vortex generators in front of the wipers/windscreen. Cuts down on wind noise from that area.

 

[RooflessVW]

Didn't Lear Jets use compressed air off the engines to blow the windshields clear?

Bleed air is commonly used for heat and defrosting.

It's a more recent phenomenon that jets aren't using bleed air.

 

[Astro14]

Bleed air was used in both the F-14 and F/A-18 to clear the windscreen.

I don’t think windshield wipers, of any kind, would, survive the speed of those airplanes, and wiping the curved canopy of the Hornet would be problematic.