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  #271  
Old 11-30-2017, 05:50 PM
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Steve Melton Steve Melton is online now
 
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an estimate. an airfoil is about 1/10 the drag of a small cylinder.

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  #272  
Old 11-30-2017, 09:04 PM
BMC_Dave BMC_Dave is offline
 
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Quote:
Originally Posted by Steve Melton View Post
an estimate. an airfoil is about 1/10 the drag of a small cylinder.

Right, but the angled antenna gives a oval cross section to the air stream so it's not as bad as a straight-on cylinder.

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  #273  
Old 12-02-2017, 08:41 AM
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steel rod counterweight added at the leading edge. not sure what will do for the radio? added some slight recessed dots to mark for drilling in order to remove easily.



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Cincinnati, OH
RV-9A, Tip-up, Superior O-320, roller lifters, 160HP, WW 200RV, dual impulse slick mags, oil pressure = 65 psi, EGT = 1300F, flight hours = 900+ for all

Simplicity is the art in design.
I was born an airplane nut. I have no explanation for it.
My Artwork is freely given and published and cannot be patented.
www.rvplasticparts.com
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  #274  
Old 12-02-2017, 09:05 AM
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Quote:
Originally Posted by Steve Melton View Post
steel rod counterweight added at the leading edge. not sure what will do for the radio? added some slight recessed dots to mark for drilling in order to remove easily.



I think you will be detuning your antenna with a steel rod in close proximity. I defer to more recent engineering grads for this analysis.
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  #275  
Old 12-02-2017, 09:49 AM
Tom Martin Tom Martin is offline
 
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Safety note: a bit off topic but please put a tennis ball or empty water bottle on that antenna tip if you are working under the airplane. While on a creeper I had the end of the antennae slide between my eye ball and eye lid. I was very lucky to not lose that eye. I know of one other pilot who has had a similar experience.
( End of off topic safety note)
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  #276  
Old 12-02-2017, 11:41 AM
BMC_Dave BMC_Dave is offline
 
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Quote:
Originally Posted by vlittle View Post
I think you will be detuning your antenna with a steel rod in close proximity. I defer to more recent engineering grads for this analysis.
I'm all for experimentation, but this is unlikely to be worth the effort. If it doesn't end up a net loss due to weight and imperfections in the shape, there's no way it's going to be a 45% reduction in drag force compared to the antenna.
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  #277  
Old 12-02-2017, 01:33 PM
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Steve, why add a counterweight at all? It looks like this is being made in two pieces, and screwed together... Just use the two pieces to clamp around the "vertical" piece, and at the base where the horizontal part comes out, clamp tightly around that as well. Surely that will prevent rotation?

I tend to agree that the drag on this short piece of (angled, and hence elliptical to the airflow) antenna is likely to be so small already, that even decreasing the drag by 90% won't make a difference that's measurable.

That said, I have an ELT antenna that also comes down and bends aft, and I definitely plan on making a fairing for it now that I've seen this one... It would look a lot better...
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  #278  
Old 12-02-2017, 05:05 PM
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Default bird on a wire but it didn't sing

192 ktas, slipped right thru my 187 target. bird on a wire but it didn't sing but the trailing antenna is bouncing somewhat. not sure if that's normal. the antenna fairing looks good. clamped with tape as shown. my belly oil cans at 1:57.

https://youtu.be/2LhFZwankY0











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Steve Melton
Cincinnati, OH
RV-9A, Tip-up, Superior O-320, roller lifters, 160HP, WW 200RV, dual impulse slick mags, oil pressure = 65 psi, EGT = 1300F, flight hours = 900+ for all

Simplicity is the art in design.
I was born an airplane nut. I have no explanation for it.
My Artwork is freely given and published and cannot be patented.
www.rvplasticparts.com

Last edited by Steve Melton : 12-02-2017 at 06:20 PM.
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  #279  
Old 12-03-2017, 10:58 AM
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Looks like (based on the tape lines) it swung to one side (tail end to right) once you got up to speed... I think you'll definitely need to get the trailing portion of the antenna clamped in there to keep it straight.

It looks like the lower portion of the white antenna mount is also round for about 1 to 1.5 inches at the bottom... Maybe the fairing should be extended up around it as well...
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  #280  
Old 12-03-2017, 01:04 PM
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how to explain the deviation of the fairing to the right at flying speed? perhaps the antenna rod is not perfectly vertical or nose wheel fairing influence.

even tho the fairing looked good after the flight it will find the trash can because it would never survive long term with the antenna response. a science experiment of a bird on a wire. I'm fortunate it didn't depart.
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Steve Melton
Cincinnati, OH
RV-9A, Tip-up, Superior O-320, roller lifters, 160HP, WW 200RV, dual impulse slick mags, oil pressure = 65 psi, EGT = 1300F, flight hours = 900+ for all

Simplicity is the art in design.
I was born an airplane nut. I have no explanation for it.
My Artwork is freely given and published and cannot be patented.
www.rvplasticparts.com

Last edited by Steve Melton : 12-03-2017 at 01:07 PM.
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