ELT Antenna - Just how much DRAG?

[LifeofReiley]

Well... I did it. I drilled the hole in the turtle deck just aft the slider and mounted the ELT antenna. Yes, I researched all the hide it here and there threads but came to the conclusion I wanted mounted per the instructions. What did I just do? How much will this 1/16" little whip slow me down? Anybody got an real numbers?
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[Ron Lee]

But I "hide" mine just in case I am wrong. I got tired of seeing its shadow flopping around on the wing under some lighting conditions.

[Mel]

Originally Posted by LifeofReiley

How much will this 1/16" little whip slow me down? Anybody got an real numbers?
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Not enough that you will ever see.

[Norman CYYJ]

How much will it slow you down? That depends how fast you are going. The faster you go the less frontal area that is exposed to the air cuz it is bent over. The slower you go the more erect it is therefore more drag. So don't fly slow it might change your stall speed into the higher numbers. lol

[mgomez]

This is the result of a calculation, not a measurement. My RV is not flying yet, and it would take more careful measurements than I care to make to detect a 1 kt change.

It's close to a one knot loss in airspeed.

That assumes a length of 24", a diameter of 1/16", plus mine has a little cone at the base, a baseline speed of 180 kt, and a drag coefficient of 1. The antenna is at a Reynolds number of about 10,000, which is why the Cd is so high.

An RV-6 or 7 has a baseline drag area of about 2.3 sq. ft, and the antenna increases that by about 1% due to the high Cd. The speed is therefore affected by about 1/2 of 1%.

A big potential source of error in this calculation is if the antenna (or, more likely, it's base) causes the flow over the tailcone to separate. A big separation wedge would increase the drag way more than I calculated above.