Airfoil shape to reduce drag have you done it ?

[SandL]

I'm happy with my gyro, but am I missing something ?
I saw a gyro at Bensen days (think it belongs to nowings) where almost every tube had an aerofoil shape tie wrapped on to it.
so looking at my machine and most others I ask is this a mod worth doing.?
The tubes out to the wheels, the mast, even control rods ?
it is extra weight, but am I missing an advantage.?
I seem to remember discussing this briefly with Vance and he was rather keen on the idea.
Has anyone evaluated this, 5pmh extra may be ? better climb even with extra weight ?
if so what is the best meterial and is there any thing to watch out for ... control restriction of control rods of course.
where is the best weight stremlining benifit, the mast ?

so have you done it and is it worth doing ?

 

[ultracruiser41]

not worth it.....still dragging a big rotor around

 

[EI-GYRO]

Streamlining the axle is on my to-do list.

I'm told Peter Lovegrove reckoned it would gain you 3 hp.

No idea whether this is true or not.

I have the foam cutting templates made.

Half-round attached to the forward edge, trailing wedge 2 x 4 attached to the trailing edge, using semi-rigid closed-loop foam in 1 foot sections.

Will see if any noticeable effect,

 

[Jean Claude]

I'm told Peter Lovegrove reckoned it would gain you 3 hp.
No idea whether this is true or not.

This is what I find using the values of the book "Fluid Dynamic drag" S. Hoerner with NACA 25% on the square mast.

 

[SandL]

who dosen't want 3 hp with no engine mods ?
especially those at a high D/A
EI-Gyro maybe you could produce and supply the foam for sale
if you do then I'm well interested.
not as easy for me as I would have to gain modification approval from the CAA/LAA but I'm sure others in other countries would be interested.
is there any down side to doing this modification ? corrosion /crack inspection maybe

 

[StanFoster]

My Helicycle streaming made a nice, measurable and felt difference. However, I had high speed numbers to start with, and these higher numbers see the biggest improvements with streamlining.

But just streamlining my landing gears trailing edge reduced drag....

 

[Jean Claude]

Still another track: A radiator box prevents the air circumvention on the sides. Therefore smaller radiator surface is required, and the gain is over 4HP to 55 mph.

 

[eddie]

My RAF had a very large radiator,I had a smaller custom one built and the drag reduction

was very noticeable,however I believe streamlining the tubing etc would be a big waste

of time unless you did the whole machine, engine, wheels, streamlined cabin,etc.

To me it would have to be all or none to notice a big drag reduction.The cosmetic improvement

might be worth it though.





Best regards,

 

[EI-GYRO]

What BarryK says is undoubtedly true, but, having a lot of drag elsewhere is not an argument for doing nothing to reduce overall drag where you can.

My logic is; If it is inexpensive and lightweight, why not, if only in the name of experiment.?

My test piece, ugly though it is, says it should be physically robust enough for the job.

3hp would be about 6% power gain, which, considering about 75% of overall power is
consumed just keeping airborne, one could expect about 20% improvement in climb-rate,
which is mostly what interests me.

Any improvement in fuel economy/range/engine cruise load etc would of course, be welcome.

It seems to me to be worth a try.

The only reservation I have about it might be any undesirable effects during true vertical descents, but this can be approached gradually.

Thanks, J-C, for your information and comments. I don't trust my maths too far.

Re radiators; My current oil cooler is larger than ideal, so I have it half shielded to get a proper oil temperature. I will now re-orient it somewhat at an angel to the airflow and reduce the cross-section exposed to the stream instead of shielding it.
Should reduce drag a little.

Peter, what I produce will be a one-off, and won't be pretty, but if it works, there would be nothing to prevent someone copying it prettier.
Detail and finish are not my strong point.

 

[EI-GYRO]

In your case,Eddie, that would be correct.
Your machine is quite powerful, and any minor improvement would hardly be noticeable.

My machine is relatively quite low-powered, Bensen VW 1835, and any improvement is welcome.

 

[SandL]

Still another track: A radiator box prevents the air circumvention on the sides. Therefore smaller radiator surface is required, and the gain is over 4HP to 55 mph.

I have seen people part gaffa tape their radiators in the winter maybe a box that you are suggesting is a better way to go, there must be many 912, 914 Mtos out there, maybe this could be a standard winter mod.

also any thoughts on the back end of the air filters? they seem to stick out quite a bit. but both the rad and airfilters need air flow which I would rather not disturb and as I have said it would be a standard design modification for me in the UK, with added paper work. but a mast cover and wheel bars should be quite easy to get passed.

 

[eddie]

Point taken Fergus, The drag reduction from the radiator was very noticable though,it was

like having a big barn door strapped on the back and taking it off gave me an increase in

speed/glide ratio,made my landings a lot better.





Best regards,

 

[Alan_Cheatham]

This might be of interest:

http://www.uflyit.com/streamline_fairings.htm


There's no doubt that streamlining can be a benefit if the weight can be kept to a minimum, the record setting Little Wing "Woodstock" gained performance with additional streamlining of it's exposed mast and struts.

https://randyroberts.files.wordpress.com/2009/06/img_9468.jpg

.

 

[Jazzenjohn]

If your goal is climb performance, I would think putting the gyro on a diet would have more effect than streamlining. For high cruise speeds streamlining seems to be beneficial. I look at Carl Schneiders Carlinator for proof of effectiveness. He was using an HKS 700 engine and getting 85 or so MPH out of it with a heavy gyro while burning the least amount of fuel of any gyro I'm aware of
. There were people that simply put an HKS on a Dom Ultrawhite and found it to be a poor performer. The difference is the prop size and Carl's attention to streamlining.

 

[Vance]

I'm happy with my gyro, but am I missing something ?
I saw a gyro at Bensen days (think it belongs to nowings) where almost every tube had an aerofoil shape tie wrapped on to it.
so looking at my machine and most others I ask is this a mod worth doing.?
The tubes out to the wheels, the mast, even control rods ?
it is extra weight, but am I missing an advantage.?
I seem to remember discussing this briefly with Vance and he was rather keen on the idea.
Has anyone evaluated this, 5pmh extra may be ? better climb even with extra weight ?
if so what is the best meterial and is there any thing to watch out for ... control restriction of control rods of course.
where is the best weight stremlining benifit, the mast ?

so have you done it and is it worth doing ?

When trying to describe the form drag of something I am trying to push through the air I consider the shape (coefficient of drag or Cd) times the area. A flat plate at right angles to the airflow has a Cd of 1. A round tube at a right angle to the air flow has a Cd of 1.2. A streamline shape may have a Cd .1.

The Predator has more than two square feet of round tubes at right angles to the air flow for a CdA of 2.4. That is effectively a 2.4 square foot flat plate. By streamlining the tubing this drag could be reduced to effectively .2 square feet.

To put this in perspective I use a CdA of 11 (a guess) when calculating the drag on The Predator. Streamlining the round tubes would reduce this to a CdA of 8.8 for a 20 percent reduction in form drag.

Induced drag comes into the picture so this would not result in 20 percent reduction in power required for some specific speed. My rough guess suggests an 8% reduction in power required to go 65 miles per hour and a 14% reduction in power required to go 85 miles per hour.

That is 8% and 14% additional power to climb or an 8% or 14% reduction in fuel consumption going 65mph or 85mph.

These numbers are just a guess based on experience with streamlining other things and the guess has not been quantified experimentally.

The Predator is a large, heavy gyroplane with lots of round tubes sticking out.

The Cavalon is a pretty slippery gyroplane and the reduced drag showed in its performance, fuel consumption and glide ratio even near gross weight.

To decide if it is worth the effort; calculate how much area of rounds tubes your gyroplane has, think about the reduction in drag and decide if it is worth the effort.

The more things are streamlined the more difference the un-streamlined things make.

 

[EI-GYRO]

If your goal is climb performance, I would think putting the gyro on a diet would have more effect than streamlining.

There's not much I could remove from my gyro and still have a gyro.
However, I have recently removed 10Kg (22lbs) from the pilot, without resorting to irreversible measures.

If I can just keep it off over the season of gluttony,..........

 

[Joe Pires]

You can now carry another 4ish gallons of gas! Nice job!

 

[Doug Riley]

Fergus, the ancient Yule holiday was placed in the northern hemisphere's winter season for a good reason. The old Druidic aviators knew that the density altitude is lower when it's cold. This allowed them to feast at Yuletide without a loss of aircraft performance. The heavier air offset the effects of the heavier pilot.

Just slim down before summer, and pity those Down Unda, where the situation is reversed.

Dropping the gross weight of a small gyro by a pound reduces induced drag by about 0.2 pounds.

 

[EI-GYRO]

And there was I thinking it was the only tolerable alternative to hibernation.

I am a Christmas-phobe by nature and temperament, but I had a moment of pure joy today when my two-year-old grandson discovered his stash of Christmas presents early.

I love it when a plan falls apart.

 

[Jerry_Forest]

NUMBERS, Numbers, #'s.

NUMBERS, Numbers, #'s.

Hi All. HNY, eh?

To answer all the questions on gyro performance enhancements, all one has to do is go to Jukka T's webpage:
http://www.tervis.fidisk.fi/JTsite/gyrocomp.html

Step 1: Download and run the program GyroCalc.zip for Mac or GyroCalcWin.zip for Windows OS's.
Step 2: enter your machine's parameters as-is. You can play around with some of them to get your actual performance curves. Hit Clear and run the Calculate box. ROC in red and L/D in green are the ones to watch.
Step 3: Click on the "Strut, Mast and Wheel Fairings" box and hit Calculate again (without clicking Clear).

The unfortunate truth is that only a very slight improvement occurs. The sample used is Bensen single seater with G3 blades, 600 lb. AUW with a 90 HP Mac running a 50" prop @ 3800 rpm.
The lines barely double in thickness, which means about 3-5 %. For ROC that means ~450 fpm increases to 470 and L/D goes from 3.0 to 3.15.

One big improvement is switching to better blades. ROC jumps to almost 700 fpm using NACA 0012's. It's fun to play around with other paramenters to see what happens.