Question for Stubby Antenna People

[davehu]

Got my Lightning a few days ago and would up on this thread 'cause my wife asked why it has an antenna her car doesn't. Good Question. I found this which all of you might find interesting. Here's Why A Modern Truck Like the 2022 Ford F-150 Lightning Still Has Such An Old-School Antenna

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[RickLightning]

SImple. Reception.

 

[Jonny Hotnuts]

I removed mine because I could hear it hiss ~80. Also . . . they are suprisingly bad for aeros. (Yes, I get the textured coil around the whips helps but....)

Food for thought:

(Posted from another site)

I have not removed my radio antenna, which was commented on in at least one thread. Now I know why because I finally did the calculation for drag from my radio antenna. Here's the calculation:

INPUTS
Antenna diameter 5/32"
Antenna length 29"
Air density 0.075 lb/ft3
Viscosity of air 3.8E-7 lb-sec/ft2
Speed 80 ft/sec (just under 55 MPH)

CALCULATIONS
Reynolds number = 0.156" / 12 in/ft X 0.075 lbs/ft3 / 32.2 ft/sec2 / X 80 ft/sec / 3.8E-7 lb-sec/ft2 = 6400

Cd for a cylinder at Re 6400 = 1.0

Drag = 0.5 X Cd X A X rho X V2 =
= 0.5 X 1.0 X 0.156" / 12 in/ft X 29" / 12 in/ft X 0.075 lb/ft3 / 32.2 ft/sec2 X 80^2 ft2/sec2 = 0.234 lbs drag from the radio antenna

At 80 ft/sec, this is 0.234 lbs X 80 ft/sec = 19 ft-lbs/sec = 0.034 hp (1 hp = 550 ft-lbs/second). The radio antenna air drag requires 0.034 hp (0.025 kw)

I averaged 35 MPG last year. If we simplify by assuming all driving was at that speed, then fuel flow was 55 MPH / 35 MPG = 1.57 gallons/hour = 9.4 lbs/hour. Power is estimated by assuming 0.5 lbs/hp-hr, so 9.4 lbs/hour / 0.5 lbs/hp-hr = 18.857 hp. Removing the radio antenna would reduce this to 18.857 - 0.034 = 18.823 hp. The resulting estimated gas mileage would be 35 MPG X 18.857 / 18.823 = 35.06 MPG.

I would gain an estimated 0.06 MPG. I drove 10,588.6 miles last year. That would be 302.53 gallons at 35 MPG, and 302.01 gallons at 35.06 MPG. The radio antenna cost me 0.52 gallons of fuel last year. The actual savings would be less because part of my driving is at slower speeds. I will pay that cost in order to listen to the radio once in a while.



I agree with the above data. However, his calcs are based on an average speed of 55 mph.
The drag will multiply exponentially the faster you go. Example: So, at 70 it will be almost twice the drag, 80 will be almost 4X the drag (guessing here, but should be in the ballpark). And while I am sure no one else drives faster than 55 . . . I do.

Plus the goofy OEM whip whistles. I couldn't take it off fast enough.

~C

 

[Maquis]

I removed mine because I could hear it hiss ~80. Also . . . they are suprisingly bad for aeros. (Yes, I get the textured coil around the whips helps but....)

Food for thought:

(Posted from another site)

I have not removed my radio antenna, which was commented on in at least one thread. Now I know why because I finally did the calculation for drag from my radio antenna. Here's the calculation:

INPUTS
Antenna diameter 5/32"
Antenna length 29"
Air density 0.075 lb/ft3
Viscosity of air 3.8E-7 lb-sec/ft2
Speed 80 ft/sec (just under 55 MPH)

CALCULATIONS
Reynolds number = 0.156" / 12 in/ft X 0.075 lbs/ft3 / 32.2 ft/sec2 / X 80 ft/sec / 3.8E-7 lb-sec/ft2 = 6400

Cd for a cylinder at Re 6400 = 1.0

Drag = 0.5 X Cd X A X rho X V2 =
= 0.5 X 1.0 X 0.156" / 12 in/ft X 29" / 12 in/ft X 0.075 lb/ft3 / 32.2 ft/sec2 X 80^2 ft2/sec2 = 0.234 lbs drag from the radio antenna

At 80 ft/sec, this is 0.234 lbs X 80 ft/sec = 19 ft-lbs/sec = 0.034 hp (1 hp = 550 ft-lbs/second). The radio antenna air drag requires 0.034 hp (0.025 kw)

I averaged 35 MPG last year. If we simplify by assuming all driving was at that speed, then fuel flow was 55 MPH / 35 MPG = 1.57 gallons/hour = 9.4 lbs/hour. Power is estimated by assuming 0.5 lbs/hp-hr, so 9.4 lbs/hour / 0.5 lbs/hp-hr = 18.857 hp. Removing the radio antenna would reduce this to 18.857 - 0.034 = 18.823 hp. The resulting estimated gas mileage would be 35 MPG X 18.857 / 18.823 = 35.06 MPG.

I would gain an estimated 0.06 MPG. I drove 10,588.6 miles last year. That would be 302.53 gallons at 35 MPG, and 302.01 gallons at 35.06 MPG. The radio antenna cost me 0.52 gallons of fuel last year. The actual savings would be less because part of my driving is at slower speeds. I will pay that cost in order to listen to the radio once in a while.



I agree with the above data. However, his calcs are based on an average speed of 55 mph.
The drag will multiply exponentially the faster you go. Example: So, at 70 it will be almost twice the drag, 80 will be almost 4X the drag (guessing here, but should be in the ballpark). And while I am sure no one else drives faster than 55 . . . I do.

Plus the goofy OEM whip whistles. I couldn't take it off fast enough.

~C

Those calculations wont be accurate with much of the antenna already within the frontal cross section of the cab.

 

[brewski]

I did a total delete. I still get FM just fine.
I wrote down the clearance on a card that I keep in the center console.

 

[Jonny Hotnuts]

Those calculations wont be accurate with much of the antenna already within the frontal cross section of the cab.

The CdA of the antenna was isolated to determine its drag alone. And the antennas placement is directly in the airway path making the vehicles overall Fa a non factor to the calc. Now . . . I don't mean to argue. I never graduated HS for that matter (not the sharpest tool or even know what I am talking about). But I do know that on the vast number of times I have held a 5' broom handle out of my window at 80 mph for fun (*almost daily) . . . I found it was quite difficult to hold onto.



~C

 

[Maquis]

The CdA of the antenna was isolated to determine its drag alone. And the antennas placement is directly in the airway path making the vehicles overall Fa a non factor to the calc. Now . . . I don't mean to argue. I never graduated HS for that matter (not the sharpest tool or even know what I am talking about). But I do know that on the vast number of times I have held a 5' broom handle out of my window at 80 mph for fun (*almost daily) . . . I found it was quite difficult to hold onto.



~C

But if your broomstick was across the front grille, the force imparted to it would subtract from some of the force that the same air would have otherwise been imparted to the grill. It’s complicated…..I have no working experience in aerodynamics, but I did stay at a Holiday Inn Express once.

 

[Jonny Hotnuts]

But if your broomstick was across the front grille, the force imparted to it would subtract from some of the force that the same air would have otherwise been imparted to the grill. It’s complicated…..I have no working experience in aerodynamics, but I did stay at a Holiday Inn Express once.

True, however, but depends on how far in front of the grill the rod is. If it's far enough forward, the rod and the grill would each have their own wetted area.

Truthfully, if the antenna was located on the bed, in the low-pressure area just behind the cab it would have no effect on CdA.


Here is an interesting read:

http://virtualv8.com/freport.htm

 

[USA EV]

We got this cheap 4" one:
https://www.amazon.com/Antenna-adapters-Aluminum-Compatible-2009-2022/dp/B09YTWDDHD

Been totally fine (didn't test AM).

 

[Phineas Magliozzi]

Got my Lightning a few days ago and would up on this thread 'cause my wife asked why it has an antenna her car doesn't. Good Question. I found this which all of you might find interesting. Here's Why A Modern Truck Like the 2022 Ford F-150 Lightning Still Has Such An Old-School Antenna

So the article says that Ford keeps the whip antennae on the Lighting for demographic reasons, basically AM radio in the wide open spaces. Yet they removed AM radio from the 2023 Lighting. Got it.

 

[davehu]

So the article says that Ford keeps the whip antennae on the Lighting for demographic reasons, basically AM radio in the wide open spaces. Yet they removed AM radio from the 2023 Lighting. Got it.

Although in May this year Ford announced that it was dropping AM radio, they quickly reversed their decision within a few days as the government expressed (a valid) concern over AM's value in disseminating emergency alerts. AM radio isn't going away on the lightning

 

[Phineas Magliozzi]

Although in May this year Ford announced that it was dropping AM radio, they quickly reversed their decision within a few days as the government expressed (a valid) concern over AM's value in disseminating emergency alerts. AM radio isn't going away on the lightning

When I last saw mine 5 weeks ago (it has taken up residence at the local dealer, awaiting parts) it didn't have AM. Has one of the updates since then enabled it?

 

[davehu]

When I last saw mine 5 weeks ago (it has taken up residence at the local dealer, awaiting parts) it didn't have AM. Has one of the updates since then enabled it?

Ford to keep AM radio on it's vehicles

 

[GoodSam]

The antenna just gets in the way when dealing with lifting the wiper and cleaning the windshield. My 3" stubby one from Amazon still is not short enough and I could not see any wire winding that would equal any proportion of the 31"? whip for FM pickup. (amazon 3") I recommend just the CravenSpeed Untenna ($19?!) black bolt cap or $0.25 equivalent. Save the whip for AM emergency announcements about the nuclear war.

 

[davehu]

(I either listen to Sirius or stream from my phone and never listen to AM radio. FM reception in my town is fine without it. I took the antenna off and screwed in a 1" bolt. zero cost solution.

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