For years everything has been about making aircraft more fuel efficient and now latterly we are seeing fairly large antennae on the top of fuselages of modern airliners. The box on the Lufthansa group narrow bodies looks disproportionaty massive IMHO. So what's the drag penalty per annum of a GoGo installation? Any thoughts?

It also spoils the lines of an aeroplane, no end in my view!

Someone told me that Norwegian's 737 wifi costs 2% SFC. Big money! (If it's true)

It is surprising that even on newbuilds there needs to be such a box. I realise it probably holds a directional antenna that needs to see in several directions, but... you would think there's a better engineering solution.

A320-NWBO (New Wifi Box Option), anyone? Or 737-MITR (Minimal Internet Tumor on Roof)?

The recent BA and VS additions are a lot smaller thank God. Why do the likes of Norwegian not have the WiFi delivered from the factory?

greg85 wrote:

Someone told me that Norwegian's 737 wifi costs 2% SFC. Big money! (If it's true)

That seems high. Just doing a quick hand-calc, I'd estimate the drag at around 200 N (45 lbf). That's pretty negligible when the engines are humming along at maybe 10,000 lbs total thrust at cruise.

Assumptions:
Antenna width = 24 inches (0.61 m)
Antenna height = 12 inches (0.30 m)
Projected area = 0.19 m2
Drag coefficient = 0.09 (half streamlined body)
Density at 32,800 feet = 0.4135 kg/m3
Sonic Velocity at 32,800 feet = 299.5 m/s
Cruise Mach = 0.80
Velocity = (0.8)(299.5 m/s) = 239.6 m/s

Fd = (1/2)(Density)(Velocity^2)(Cd)(Area)

skipness1E wrote:

The recent BA and VS additions are a lot smaller thank God. Why do the likes of Norwegian not have the WiFi delivered from the factory?

Wifi usually isn't an accessory offered by the manufacturers.

It is an awkwardly shaped rotating antenna that all must be mounted on top of the fuselage. An integrated design that is not on top of the fuselage skin could reduce drag, but that would create a large structural modification and create a maintenance challenge.

jetblueguy22 wrote:

skipness1E wrote:

The recent BA and VS additions are a lot smaller thank God. Why do the likes of Norwegian not have the WiFi delivered from the factory?

Wifi usually isn't an accessory offered by the manufacturers.

American, Garuda and others have factory deliveres with WiFi already visible on the fuselage roof.

skipness1E wrote:

The recent BA and VS additions are a lot smaller thank God. Why do the likes of Norwegian not have the WiFi delivered from the factory?

I would guess that it is to save money. Some airlines install their winglets after delivery as well because it saves money.

kabq737 wrote:

I would guess that it is to save money. Some airlines install their winglets after delivery as well because it saves money.

Interesting that installing aftermarket Winglets would save money. Wouldn't that require the airline to front the cost of the modification? Wouldn't there also be a middleman like APB that would mark it up for their profit?

rjsampson wrote:

kabq737 wrote:

I would guess that it is to save money. Some airlines install their winglets after delivery as well because it saves money.

Interesting that installing aftermarket Winglets would save money. Wouldn't that require the airline to front the cost of the modification? Wouldn't there also be a middleman like APB that would mark it up for their profit?

I had the same thoughts as well when I was originally informed of this practice however there are airlines out there that do it. I believe Delta does it with their 737s but I could be incorrect on that...

I believe the location of the blister is defined by where it can ideally benefit from Area Rule. If there is a location along the roof where there's an optimum place then that's where it goes, where the dimensions of the body are such that adding the blister does the most good for this.

kabq737 wrote:

I had the same thoughts as well when I was originally informed of this practice however there are airlines out there that do it. I believe Delta does it with their 737s but I could be incorrect on that...

I agree, I find it very strange that DL or any other airline would order a less efficient 737 aircraft from Boeing with a straight wing, only to take on their own cost. Boeing can do it at their factory, or maybe DL can use APB to do it aftermarket. I wonder if the Split Scimitar winglets roll off the line by default.

I can't imagine Airbus offering any A32x CEO or NEO with straight wings and no Sharklets. Anyone with industry knowledge on this?

Channex757 wrote:

I believe the location of the blister is defined by where it can ideally benefit from Area Rule. If there is a location along the roof where there's an optimum place then that's where it goes, where the dimensions of the body are such that adding the blister does the most good for this.

.

DISCLOSURE: ViaSat is a client of mine, which offers far better WiFi, including over the ocean.

My guess: Whatever the fuel SFC penalty that comes from that antenna bump, is more than offset by passengers paying exorbitant prices for WiFi (and I'm guilty as charged on practically every flight). I would think that this is particularly lucrative for airlines that don't provide heavy IFE systems and screens, thereby requiring you to BYOD in order to watch the media they provide. For a price.

Thoughts?

rjsampson wrote:

Channex757 wrote:

I believe the location of the blister is defined by where it can ideally benefit from Area Rule. If there is a location along the roof where there's an optimum place then that's where it goes, where the dimensions of the body are such that adding the blister does the most good for this.

.

DISCLOSURE: ViaSat is a client of mine, which offers far better WiFi, including over the ocean.

My guess: Whatever the fuel SFC penalty that comes from that antenna bump, is more than offset by passengers paying exorbitant prices for WiFi (and I'm guilty as charged on practically every flight). I would think that this is particularly lucrative for airlines that don't provide heavy IFE systems and screens, thereby requiring you to BYOD in order to watch the media they provide. For a price.

Thoughts?

Of course it is. Airlines are businesses after all. if there wasn't some benefit (either in cash or service differentiation stimulating sales) they wouldn't do it.

The cash element has to be the most important. Sell it to the people down the back, and give those up front limited service which they can always pay to extend. It's a business after all and WiFi is now being seen as essential in today's connected world. It has to pay its way though.

As the antennas get smaller, even more airlines will get into this. This include the ULCC airlines who watch every penny.

Channex757 wrote:

I believe the location of the blister is defined by where it can ideally benefit from Area Rule. If there is a location along the roof where there's an optimum place then that's where it goes, where the dimensions of the body are such that adding the blister does the most good for this.

No. There is a lot that enters into it. Various locations are studied from the drag standpoint, but there are also structural considerations and issues of what is under the crown skin (life rafts, etc.). Plus, airlines can have preferences - note how the Gogo 2Ku radome is installed aft of the wing on Aeromexico 737-800s, but ahead of the wing on Delta 737-800s.

There are design constraints that have a big impact on the shape of each radome. Lately, birdstrike resistance has constrained the shaping of the front half of the radomes.

My disclosure: I have done aero design work on the Gogo 2Ku radome, Panasonic radome, LiveTV FlyFi radome, Viasat radome, Row 44 radome and several military radomes. Plus, I have done installation analysis work on these and the LiveTV legacy radome, Boeing CBB radome, TW550 radome, CMA2102 radome, Aerosat Low Drag Radome and the Honeywell radome, on many different airframes.