Streamlining my Helicycle landing gear

[StanFoster]

Vance- Thanks for the comment. The new look is pleasing to my eye........but they better give me some drag reduction! I am also going to look forward to some new data runs. Doug- Thanks to you also. My wheels have around an inch of clearance, so no scuffing! One last thanks to Nicolas for providing me with a sketch that guided my direction building these fairings. Light and strong, but it took some patience to make them come out with nice curves, no wrinkles, and set with 6 degrees of incidence. I am going to approach 112 mph in increments, doing some yawing to see if anything funny is going on. I will be very happy if I pick up 3-4 mph. Stan

 

[GyrOZprey]

Those fairings look very smart Stan. Be interesting to read the results of your flight test data. You must be busy ( catching up since your BD get-a-way) --- missed reading your variety of thread inputs!
cheers from the Butterfly cackle-berry bombers!!! :lol:

 

[StanFoster]

The first two pictures are a test sample of using silicone to attach the internal webs of my fairings to the landing gear. The purpose of the silcone bond is just to prevent rotation, but in all honesty...the curved fairing resists this a lot anyway. I grabbed the bottom ends this morning and they are solid!

I took some more shots from the rear in the center. I still had clamps yesterday on the left side. You can see the 6 degrees of incidence I have built into these fairings, but as they progress outwards and become more vertical...the incidence angle was gradually "rolled" out. Thats alone took several hours to figure out how to make flat aluminum sheets behave as they were rolled into a conical shape. My trick was to over cut the width of the bottom skin and make it conform to the proper trailing edge intersection that the top fairing had to be at. Then trim off the excess. Worked good for me. It actually was simple after scratching my head and wasting a few cuts of aluminum!

I was looking at my fairings real early this morning...and something wasnt right with the paint scheme of my stripes. Then it just dawned on me how stupid I was. I forgot to put the matching black/grey pinstriping that connects all my burgundy to white on the cabin and tail. I put the pin striping on real quick and it just melted in the fairings with the cabin when its seen in person. The last two pictures shows the pinstriping... Part of thr striping had to go onto my straps, but in my next life I will design the straps to be out of the way completely!

Anyway....testing will begin this weekend. If its gusty out I will just see how they handle....and wait for calm winds to start recording my high speed runs.

Stan

 

[Lee Scatt]

Stan, my thoughts have gone divergent from yours. Those legs look so nice, if you lost 2mph, I would say Adios!.
It's kinda like spiked heels on a stripper, totally useless except for the shape of the legs.
Keep'em no matter what!

 

[All_In]

It does look nice buddy!
Looking forward to your testing this weekend.

 

[StanFoster]

Lee- Some think that you cannot change peoples behaviour. Your post is very convincing to me to leave them on even if they slow it down! But....I must see an improvement.

Chris....thanks...Yes, I am busy with starting a spiral stairway and a curved one.


John- I can not let the pretty fairings bias my data figures I will be taking. I dont want to feel like I do when I wax my truck and "think" I can see better gas mileage. However....Lee is pretty convincing. Dang....I am nervous....and hope I can at least see 2 mph increase.....

The drag calculators show anywhere from 3-5 mph...depending on what the total CD of my Helicycle is. I am using conservative figures biasing my goal down to 3 mph. I have actually 8 foot 4 inches of landing gear exposed to the relative airflow....this is not the longer angled distance...but the actual cross section going through the air. I cut that down to 8 feet just assuming the first two inches are consumed at the cabin fairing intersection with turbulence.

Cant wait to test fly. My laser was checked with my pitch markings in the cabin. Nothing has changed...so I will have a brand new sheet of paper on my clipboard to compare previous data to. Again, the figures are corrected to DA by plugging in the barometric pressure...temperature..and dew point.


Stan

 

[hillberg]

Dem be sexy legs ! It adds to the style,slick !

 

[RotoPlane]

If those leg chaps don't degrade the flying quality, I say keep them on….they really dress up those spindly legs. I believe they are bound to improve airspeed.

 

[StanFoster]

Don and Ed- Glad you like the looks of the fairings. After seeing the before look...I am loving them. I took the Turbinator outside for a better photoshoot of the fairings.


Stan

 

[StanFoster]

4 mph plus----gain in mph

4 mph plus----gain in mph

I am ecstatic. My first test flight of my fairings is complete....and with God as my witness on this Good Friday.....the fairings are giving me a 4 mph plus gain at the top end. My last flight without the fairings and todays test flight had the DA within 50 feet....miniscule adjustment isnt even necessary.

My speeds were gradually increased as I watched for any nose up or down sensation....and I could feel nothing but it riding on rails. I went directly into the light steady wind we had today....and let the GPS stabilize and I recorded the top end speed. I then flew directly downwind and down on the deck and let the speed stabilize till it stayed the same...and recorded. Quick averaging in my head showed over a 4 mph gain. A big smile came over my face...but I had to go repeat this two more times. Each downwind and upwind run came in at the same mph ....so I knew I had something here. A honest to God 4 plus mph increase.

I will post the math I used that showed a potential 3-5 mph increase....the unknown is what is the CD of my whole Helicycle. The numbers fit....and I will type them up later on.

Stan

 

[Doug S.]

Stan
Looking sharp and functional, you just can't get any better then that.

Very Snazzy....

Doug S.

 

[All_In]

Life is good when math matches reality!!!

Really nice work and it looks better!!!

 

[RotoPlane]

That is one of the things I like about you Stan….if you decide something may be worth doing, you then go for it and do it….and do it well!

A four mph increase is nothing to sneeze at (ah…that means it has a "positive aspect" in my area) and it is good looking to boot.

 

[ylf]

Looking good Stan.

 

[Vance]

Congratulations Stan!

Congratulations Stan!

You are an inspiration to us all.

I share your joy.

Thank you, Vance

 

[StanFoster]

Thanks everyone for the comments. I am extra satisfied with the first test results. I just did top end testing yesterday, and will be plotting a new power curve with subsequent flights. I have an interesting set of numbers to post that backup mathematically the results. I am on my cellphone right now, and can't post the numbers in neat rows. Later I will post them from my computer. Stan

 

[Gyro_Kai]

This is great news! We have all been waiting as eagerly as you for the results, I think. And on top of the 4mph the looks also improved (if that is at all possible).

Good work!

Kai.

 

[StanFoster]

Kai- Thanks for the comment.

Here are the numbers that I based my optimism on for the potential of obtaining a 3-5 mph increase at 110 mph.

It is stated that roundpipe has a coefficient of drag...(CD) of 1.1 to 1.2 depending on where you look up the info. I used the more conservative 1.1 so as to not start off with more promising numbers. Using the formulae for horsepower... CD x Sq. ft. X velocity cubed
HP = ___________________________________
150,000


I found the horsepower needed to first drag my landing gear through the air at 110 mph. Plugging in 1.1 for the drag coefficient of the landing gear l.....and then plugging in exactly 1.0 square feet which is area exposed perpendicular to the wind of my 8 feet of landing gear that is 1.5 inches wide. ......multiplying by 110 mph cubed.....

This computes out to 9.76 horsepower to pull the landing gear at 110 mph. I have attached a computer analysis sent to me so kindly by Nicolas showing my actual analysis of my fairings shown as the teal colored line marked Stan 1. This shows a CD of 0.3 for my fairings. Running this number into the calculation arrives at the fairings only taking 2.67 horsepower at 110 mph. The key element is that I now have 7.1 horsepower saved to put back into making the helicopter go faster.

After I carefully recorded and compared the results...I came up with at least a 4 mph gain in airspeed.

I do not know what the CD of my helicopter is, but I made an educated guess by this method.........

I plugged in various CD numbers clear from a Bonneville type clean ship of 0.2....and knew it would be more than that. On the upper end....I went clear to a CD of 1.0 which I knew it would be less than that because the Helicycle is pretty slippery. The horsepower to fly at the upper CD ranges of .9 and 1.0 actually exceed the 100 horsepower of my turbine...so they were eliminated. I poste here the cd ranges of 0.5, 0.6, and 0.7. I am posting here horsepower figures for 110 mph and 114 mph which is the 4 mph gain I measured.....and then reengineered the calculations back into the helicopter HP figures.

0.5 CD at 110 mph 53.24 HP
0.5 CD at 114 mph 59.26 HP
required HP increase 6.02 HP


0.6 CD at 110 mph 63.88 HP
0.6 CD at 114 mph 71.11 HP
required HP increase 7.23 HP

0.7 CD at 110 mph 74.54 HP
0.7 CD at 114 mph 82.97 HP
required HP increase 8.43 HP


Next I took my conservatively obtained 7.1 horsepower that the fairings give me and match that power figure to one of the above. The 0.6 CD matches the closest as it computes taking 7.23 more horsepower to fly the 4 mph that I have gained by testing. These figures just verify to me that the math fits here nicely. Again...I am using the lower CD of 1.1 for my landing gear which lowers my expected horsepower increase.

Power required goes up with the cube of the airspeed and though I had over 7 extra horsepower...the math in the 0.6 CD column consumed it all at 114 mph.

Now...for those here that are really studying this...please go back to the chart where Nicolas shows my airfoil if I also streamlined the leading edge. It is the redline and it would lower my CD to almost 0.2 However....I plugged in the figures for if I also streamline my leading edge...and even using the 0.2 CD in the formulae....the horsepower saved is only another 0.89 horsepower. It takes 1.9 more horsepower to go only 1 more mph. I would only gain about 0.5 mph. Nicolas had mentioned that in an e-mail that I would not see much difference streamling the nose. He was exactly right.

For the fun of it ...I computed the drag in pounds of my landing gear taking 9.76 HP to pull them 110 mph.

Each HP is 33,000 foot pounds per minute Multiply that by 9.76 HP and you arrive at 322080 foot pounds per minute. 110 mph is 9680 feet per minute.

I divided 322080 by 9680 and arrive at 33.27 pounds of drag the landing gear create at 110 mph. With the fairings...they only create 9.07 pounds of drag.

I am eventually going to post my new power curve....but for right now....I am enjoying flying without tabulation. That really is tedious work if done right.

Today I just flew and took in the farmers all out planting. Thanks everyone for the interest in this thread. I am submitting an article to Roy for his PSF magazine. He told me he would supply come graphs to replace my sketches.

Stan

 

[All_In]

Wow very cool indeed Stan.

You do know your stuff buddy and it is great to have friends like Nicolas!
I really do love how math matches reality.

I like the way you always teach and tell the good, bad, and the ugly no mater what!

 

[StanFoster]

I forgot some data! Earlier I was talking to Passin' Thru about my fairings. Thank you Pete for your compliments. I mentioned to Pete that early in this thread I had measured the skids flew 6.9 degrees nose low at 110 mph. I set the incidence angle of my skids to 6 degrees, in anticipation of all that reduced drag causing the skids to fly less than 6.9 degrees. I wanted these fairings to fly at near to knife edge thru the air as much as possible. The CD increases as the chordline of the fairing goes either way of 0 degrees. ........................................................ You can see the 6 degrees of positive incidence sitting in the hanger, and how the incidence angle decreased as the fairings become more vertical going down the landing gear. I have seen other fairings with no apparent incidence angle built in. They have to not be at minimum drag when the helicopter is more nosedown going fast. I need to go out next flight and measure what angle my skids are flying at now with my fairings. I very much expect the skids to fly closer to 6 degrees with the fairings. Stan