Streamlining my Helicycle landing gear

StanFoster

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I thought I would start a new thread on my "attempt" to make some landing gear fairings for my Helicycle. Here are some pictures of a posterboard pattern that initially made me realize this was within my skill level, some aluminum flashing that is painted white and brown on opposite sides. This stuff is perfect and it is very tough.

A picture of my landing gear that exposes 8 feet of 1.5 inch tubing to the airstream. Any source on aerodynamic streamlining shows there is a lot of potential drag reduction here. As mentioned in the other thread it figures out to 8.8 horsepower being consumed to pull these through the air at 110 mph. This can in a perfect world be reduced to 9% of that....but I am not in a perfect world, nor is my work.....and if I can carefully align my airfoils chordlines with the airstream, I am shooting for only getting the drag down to 20%. I feel that is a very achievable conservative number....and would give me 7 extra horsepower to go either in reduced collective....or higher top end.

Like I have mentioned....these must look nice or they are not going on. I have a fast enough ship, and wont trash its looks to gain 5 mph.

If I fail at this attempt...it wont be my first failure in life...and I will still learn from this. This project will either succeed or fail quickly as it is #1 priority to do this month. In case anyone is wondering about my windshield project...it is happily in a stalled mode as I find the time to get back on that project.

The last picture is my digital level. I am going to 0 it out with the skids nice and level in my shop....then make a 100 mph flight tomorrow. It has a feature that is called a "Hold" button. Whatever the angle the skids are down in the front...I will know EXACTLY!!!! I will then optimize the airfoils chordline to be parallel to the actual angle that my Turbinator is flying at 100 mph. I chose 100 mph..because I have decided to optimize my cruise at that speed....and just be enjoying less collective load to my drivetrain. I will still be able to gain the extra mph that whatever my extra 7 horse will give me.

Stay tuned...success or failure.....it will be coming out this week. I have several stairshop glueups that will allow me an hour between to pursue this new project.


Stan

Stan
 

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bryancobb

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Nothing like stockings on a nice pair of legs! LOL
 

akoschier

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Stan, I would have put a few tufts on the gear and taken a pic in flight to document how they are oriented i addition to your level on the skids.
avk
 

bryancobb

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I think you may be overanalyzing it Stan. ANY positive angle of attack between +0.1 degree and the critical (stall) angle of attack of the fairings, will give some small amount of lift while creating less drag than the round pipes.

You could probably eyeball it and get it within that range.
 

bryancobb

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Ok, I was just thinking out loud. Most airfoils stall at somewhere about 18. I would think that an eyeball could get it between zero and 18?
 

StanFoster

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Come on Bryan! What good would streamlining my landing gear with airfoils that are sloppily eyeballed, and say off 5 degrees. That alone would be adding back drag I could have saved. I WANT the chordline of my airfoil as close as I can get , and I am not going to trust my eyeballs, but a very methodical and sure way. I want to keep my airfoil perpendicular to the airflow all along the changing angle they will make along the lsanding gear. I am sorry, but I am trying to do this in a planned way and not by luck. Stan
 

StanFoster

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Heres a rough draft of a fairing made out of thin aluminum. No effort was made to space my rivets...I just eyeballed them. I will be using 0.032 aluminum for the real fairings. The front edge will be chamfered to fit the round pipe on the inside and will be held back from the centerline of the landing gear. The stuff in the pictures is on 0.016 and is too thin to hold a straight edge.

This is roughly how it will look, however, I am having problems adjusting to the look on my ship. I mentioned first thing that these cant look cheesy. So far I am satisfied with getting them made with a nice curve and keeping them square with the airflow, but right now I dont like the looks of them after I made a temporary one for the rear leg. It has to be pleasing to my eye or I am not making them. In this case its form before function.


Stan
 

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Jason O

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going all out

going all out

Hello Stan,

You mentioned using a "trip" wire to help reduce drag on a round object. After you see what angle the skids are flying at at 100mph, you could use the trip wire (tubulator) on the skids to try to reduce their drag.

Jason
 

StanFoster

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I did the test flight to measure the angle of my skids at 110 mph.

The first picture shows me zeroing out my angle cube. Love that little thing. I bought it from Bear Perkins. EXTREMELY ACCURATE!!

Anyway...I had my helicopter on a perfectly level floor....then placed the angle cube on my door track nestled up against that bolt and the windshield. Perfect repeatability.

Next I lit the turbine and away I went. Low altitude today as the ceilings were down. I wanted to hug the earth anyway so as to know I was flying level.

The second picture shows a strong 110 mph. 112 mph is about all she will go as any more collective and the belts will start to slip just a little as I can tell by watching my rotor rpm. By the way, see that bolt head with the yellow mark on it between my ASI and my rotor tach? Thats my bleed air for my ASI and when my ASI says I am going 110 mph, thats how fast I am going through the air. I have my ASI set with averaged runs 180 degrees apart into and with the wind off my GPS. I set my ASI once last fall and it has been within 2-3 mph all the time.

After I was flying 110 mph at a constant altitude...and I should say constant attitude....I locked my collective....and placed the angle cube exactly in the door track at that bolt...and hit the Hold button on it. It read 6.9 degrees.

So, my skids are 6.9 degrees low in the front when hustling along at 110 mph. Now when I am still experimenting with my fairings...I will block my skids up at the rear until the level reads 6.9 degrees again. Then....the chordline of my airfoils shoul be level. This will assure that I will have the airfoils set at the optimum angle for 110 mph.

Vance made a good point to me on the phone yesterday. He noted that I would probably have a little less angle with streamlined landing gear due to less low down drag. Good point Vance, and my above paragraph may just be altered and have me set them say around 6 degrees anticipating a little less skid angle. In all reality a couple degrees either high or low will not make that much difference.

Nicolas kindly sent me a nice computer estimated drag curve for my particular airfoil I am trying to make.

After I put on my rear mockup fairing...I did not like the pair together. They were too wide...so I narrowed both 1.25 inches and they look more pleasing to the eye. This new dimension is what Nicolas sent me performance drawings on.

The jury is still out on my fairings. I have ordered some 0.032 soft aluminum, and I will be trying to bend a slightly bowed airfoil shape around my landing gear. I might try riveting the bowed trailing edge first...then rolling in the airfoil shape. Got to try something...but even if I end up with flat top and bottom profiles...Nicolas sent me performance drawings for both tailored to my dimensions. I really appreciated that guy and respect his being an aeronautical engineer. Anyway,..there isnt that much more drag with flat surfaces...but I still will try to ease them into an arc. As I told Nicolas...I can bend a flat sheet ok, but trying to bend a bowed shape that better mimics an airfoil had me pulling my white hair out.

So, even if I knew they would improve my performance...they arent going on unless they look nice. I dont mind trying to learn a new skill.


Stan
 

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choppergabor

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I like how you think! Have you done anything of this kind of work in your life before? LOL Good job Stan. I am very interested to see the results of your experiment!
 

bryancobb

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I see an English Wheel coming in on a freight-truck.
 

StanFoster

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Gabor- Thank you sir! We think like brothers from different mothers. My excitement for these fairings was rained on yesterday when I just did not like my mockups. I had them a little too wide trying to maximize the coefficient of drag. I narrowed them down and now I like them. The first ones reminded me of those chickens that have the huge feathery legs. Can't think of the breed name, but the proportion just wasn't right until I narrowed them down..................................................... Now I have the known skid angle to set the incidence angle to. I am going to make some internal U-channel webbing to space the top and bottom skins so they will slip tight around my landing gear. A piece of wood will be sized to form these U-channels. Lots of fun stuff ahead, but, they still have to look nice or they just will go to my own pile of scrap aluminum. ..................................Bryan- I could use an English wheel, and a lot more different tools. Stan
 

StanFoster

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My aluminum came the other day and I started on one of the front fairings.

The front edge where it sandwiches onto my landing gear will be cut so as the surface of these fairings will be slightly behind the centerline of the landing gear and right off a line tangent to the landing gear. I will have to file the inside lip to a bevel on both the top and bottom skins so they knife edge onto the landing gear.

I will make some internal U spacers to act as webbing to accurately space the width of these skins and to set the for/aft distance on the landing gear also.

The trailing edge is set 6 degrees low in the rear with the helicopter sitting level. When its flying at 110 mph, the fairings should be level and at minimal drag...which is what I am after.

I decided to hold back the front edge of the top and bottom skins...1/4 inch aft of the landing gear centerline. This measures out real close to being right on the tangent line from the trailing edge to the outside of the landing gear. Nicolas sent me an excellent diagram which I am following. Next will be the internal webs.

Once I get all four done....if they look good, then I will take them up to my body man for painting. If they dont look good...they wont be installed.

Stan
 

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WHY

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HI Stan

are you going to test this in two separate stages, first with only the front fairings and then with all fours fairings ?? These might make your control responses quicker ??

Tony
 

StanFoster

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Tony- No, I am going to finish this front one to the point of just before installing it. Then I will make the other 3. There is just too much information out there that shows me there will be a nice drag reduction. Totally confident of that, but they must look nice enough to have them painted. I will then attach them and go fly. I know I will have more top end speed. I will find out then. The last two pictures show the rear view of the fairings. Most of the drag is behing the landing gear and the fairings reduce most of it. Stan
 
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gyrodeputy

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Stan,
Maybe I missed it in my reading of your posts. Are you going to test fly before you have them painted? I think it looks amazing. Your abilities and talents reflect very well. I can see how they would reduce drag. I can't see spending money on paint before a test flight. Just my own ramblings.

Stay safe.
 

Roundwing

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Stan,

Would you be able to make those fairings to fit if the tubes were straight instead of curved like they are?:D
 

StanFoster

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Heath- I know they will reduce drag, and I was going to have them painted without test flying if I have them all made without any wrinkles. But, your question has merit, so I will consider how much extra effort it will be to make my attachment straps, and rivet the straps on. I can just drill out the rivets after the test flight. There will be no rivets into my landing gear but only into the fairings. My feelings are there has to be a nice reduction in drag as I have 8 feet of 1.5 inch pipe exposed to the airflow...................................................................................................... The fairest test would be to go make a high speed run without the fairings, go install the fairings and top off the fuel and make another high speed run to see how fast she flies then. My drive belts only will handle so much horsepower and from experience, I can watch my rotor tach as I reach the top end limits. My rotor rpm starts to decay slightly without the engine rpm going down...............proving my belts are slipping. So say my belts slip at 112 mph now, and I can go 117 afterwards, this worked very nicely. If I gain only 2 mph, then I gain only 2 mph and it still is worth it if they look nice also. ..........................................................Rick- God, I wish the landing gear were straight like an R22's are! It would be MUCH easier just to bend an airfoil shape and slip it over the landing gear! I am not a tin bender and I find this project a challenge. But part of this project is to try to teach my klutsy self how to learn a new skill. Wood is much easier to form in my opinion. I can't sand out wrinkles and kinks in 0.032 aluminum....................................................I had my doubts about this project when I made the mockup out of thin flashing material. But so far I loke the way the 0.032 stuff is behaving. I still won't pou them on if I don't like the looks of them even if i gsine 10 mph! Sometimes form before function applies. I have a fast ship now, and wouldn't want a faster ship that looks clunky. Stan
 
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bryancobb

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Stan,
Since you are an accomplished "wood bender" have you thought about forming them first, out of solid wood, and then working an annealed piece of thin sheet aluminum TO THE WOOD FORM with a soft leather mallet?

Just thinking out loud!
 

StanFoster

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Bryan- Show me how to bend aluminum around a compound curve! I could do it with lead sheet.... I do not know how with aluminum....:confused:


Stan
 
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