Strut fairings

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ghostflyer
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Strut fairings

Post by ghostflyer »

Some members have strut fairings fitted and some don’t. I was always wondering when fitted did they help. I have done many hours in my 170 without but had a engine change [180 hp] a while ago so performance went up plus drag also went up too. So I fitted fairings to both ends of the strut and have been flying this way and trying to note performances differences. Is there a difference? Well Y. E. S ,sort of ,I think. Maybe . I read today that Cessna fitted them years ago to decrease drag and only admitted to about a 2 to 3 knot increase . Yep, that sounds about right . Maybe ?
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170C
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Re: Strut fairings

Post by 170C »

ghostflyer some of learned members may address this from a technical aspect, but I added strut farings years ago and in my opinion they are for asethetic purposes ONLY! I have serious doubts any of us have the technical equipment to properly measure the minute differences, if any, that strut farings on a 170 would make compared to the simple rubber gasket type material originally installed at the 4 struct ends from the factory. IMHO they look better, but are a pain in the butt to remove so the annual inspection can be made. The two piece ones are likely much better when it comes to removing and reinstalling, but then you have multiple screws. I think what you are seeing is the difference in the engine power.
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Re: Strut fairings

Post by GAHorn »

During original aircraft certification ... the aircraft is tested numerous times using instrumentation much more accurate, calibrated specifically for the purpose, using higher-quality probes and capable of providing data capable of consistency comparable to other flights of the same aircraft .... for the accuracy of such matters.

In the flight YOU (or any of us) likely make after such mods... we rely upon well-used "serviceable" instrumentation with many differences which deviate from standardized "control" data obtained in previous/subsequent tests. The deviations that exist are more numerous than most of us realize.

Example: Where was the C.G. of the subject aircraft during the test? (Was the aircraft EXACTLY the same weight and CG as the flight made previous to the modification? (Was your answer "yes"?)
Well then,... that means you replaced the fuel and oil consumed during the previous test... right? (And it's important because it influences AOA which influences Airspeed indications of the years-old indicator.)

And it means that you did the after-mod test either on the same day (in which the temperature and density altitude changes over the elapsed hours)... or you did it on a different day (which means the instrumentation you used changed calibration in addition to the changed atmospherics. ) Chances are you didn't even compare the exact density altitudes of the two flights... you just went up to the same indicated altitude and saw what you perceived to be a difference. And was that an analog or a digital airspeed indicator? What parallax-position standard did you use? :wink:

I was never an engineering test-pilot. But I witnessed the results of instrumentation test flights and the efforts made to avoid deviation of tests was/is mind-boggling. As a production test-pilot making post-production performance tests at the company I flew for, we even wore a standardized uniform as part of the identicality-requirements of the test (which we all thought was pretty silly, BTW.) Inventory of each cabinet/compartment on the aircraft was controlled. The instrumentation flights (made previously by engineering) used dual-probes of high quality with confirmed accuracy between repetitive flights. Why? Because the customer's pilot who might claim the AOA indicator was out-of-calibration might later claim the company's failure to correct his perception is why he ran off the end of the runway at Rifle, Colorado ...rather than the braking-action-reports he claims were bogus. Company lawyers received copies of our test results which were filed with the corrective action reports of that airframe and kept by the company for years.

The flights the rest of us make with our personal airplanes are very subjective, and that final judgment is influenced not only by factors such as those above but are also influenced sub-consciously by how we feel that day by how much we spent on the modification. (Yeah... I think it's a little faster.....)

And Frank's 172 with a Bolen conversion either with or without fairings ....would never be able to go any faster until he re-paints something other than GREEN!
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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ghostflyer
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Re: Strut fairings

Post by ghostflyer »

I totally agree with you George on this one , but we all get to know each squeak and rattle and the hum of our aircraft . I have flown this sector many times ,set the aircraft up as I normally do and waited for any changes. I am still waiting .but drag reduction can help. I know for a fact if I have been into the swamp landing areas and the aircraft has mud and dirt all over it it is very sluggish in its performance .
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Re: Strut fairings

Post by GAHorn »

Yes, I understand. But at least in theory...... any reduction in turbulence created by airframe should result in reduction of induced-drag...(remembering that drag increases as the square of velocity... if the fairings increase speed, then that gain can only increase to the same restriction of drag as previously, i.e., it's going to be a miniscule improvement, if any).... it does give a more-finished appearance to the eye... which is probably the real reason Cessna Marketing approved the addition of the fairings. 8)

If you like them and plan to add them, Frank's suggestion of the split-types will simplify the matter.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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170C
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Re: Strut fairings

Post by 170C »

Boy George (pun intended), you know how to hurt a (green)guy :mrgreen: :lol:
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Re: Strut fairings

Post by DaveF »

Test them like wingtips ... one kind on one wing and a different kind on the other. Go fly and see which side of the airplane goes faster!
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ghostflyer
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Re: Strut fairings

Post by ghostflyer »

I used to fly a Cessna 182 with really big droopy wing tips. Theses tips did make a difference on landing. You could hold it off the runway [about 4 ins off] and then at a very slow speed until very little forward speed it would then suddenly drop . I,was always looking for a good head wind so to make a near vertical landing .it didn’t happen but a lot of fun trying. But on a crosswind it was a bitch to land, you had to be very sharp on the rudders .
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