Analysis of the Belite airfoil

Hi everyone,

A Belite follower (Theodore Fails) wanted to analyze our airfoil, so I sent him a CAD drawing of a rib cross section. Ted did a very able job of tracking down the likely origin of our airfoil. It's fascinating stuff. I thought of summarizing it, but Ted's letter to me is well written and is a good aeronautical detective story. With Ted's permission, here is his analysis. Enjoy!!

-- James Wiebe


James:

Here is progress report on analysis of the Belite airfoil:

1) It is clearly a Riblett airfoil, but it is outside of the matrix of airfoils covered in the book "GA Airfoils." From personal discussion and correspondence with Mr. Riblett, I was able to extrapolate from his data and closely duplicate the Belite airfoil. (Mr. Riblett, at age 80 was delightfully cogent on the subject, though he could not recall if he had in fact designed an airfoil for Kitfox. He did have some suggestions for Ultralight wings which I will cover below.)

2) The Belite airfoil has a built in 2.37 degree angle of incidence, giving some nominal lift at zero angle of attack.

3) The actual designation of the foil, using Riblett's method of nomenclature is GA30-8M12. "GA" means it is a Riblett foil using his method of direct addition of form ordinates to camber ordinates. "30" means that maximum foil thickness occurs at 30% of chord. "-8M" means that the camber is a slight modification from Riblett's camber level -8. Perhaps "-8.16" would be a better description, since the Belite foil is about 16% more cambered than Riblett's -8 camber. "12" means that the maximum foil thickness is 12% of chord. Maybe GA30-(8.16)12, whatever.

4) In my talks and correspondence with Mr. Riblett he suggested that for Ultralight foils, that a good choice would be a GA25-815 foil. It would be thicker overall and thicker at the leading edge, allowing a larger spar. Whether it would be worth the cost of the change or not is an open question, or even if it would improve performance at all.

5) See attached jpeg showing the Belite foil overlaid on the GA30-812 foil. The GA30-812 is closest foil that falls within the span of Riblett's data. As per 3) above, the Belite foil is more cambered than any of Riblett's standard foils. (His book covers four camber levels, -2, -3, -4, and -6. He sent me some unpublished data adding camber level -8.)

6) The small amount of washout in the Belite wing is also in accordance with Riblett design parameters. This allows a lower stall with good control and pays a lower price in drag a cruise speeds. Good stuff.

Sorry it took so long, but after I got a copy of the Riblett book and your foil did not match any of his, I naturally assumed it was something entirely different, so off I went on a wild goose chase. After learning a LOT about a LOT of other foils, I decided to just give Harry a call. The Belite just Looked like a Riblett foil.

The next step for me is to do some computational fluids testing of some foils that I am interested in. I like your airfoil ... very much. I will include it in my test matrix, and let you know the results if you have any interest.

Lastly, I am curious about the bracket drawings that you sent. Being a manufacturing engineer in my day job, I wonder how you actually make these things. Hog-out? Weldment? Sheet metal fabrication? What sort of quantities do you buy in? FYI, I have a Haas VF-3 and I know how to use it! If I get a moment I may examine these items for structural optimization, you may be able to save some mass or cost or both.

Anyway, sorry for the delay, and again, let me tell you how much I admire what you are doing in the Ultralight market. Keep up the great work.

Ted

Sharpness

Chapter One: Clouds

The recent rains and intermittent sunshine have caused the countryside around Wichita to explode with green. Planted fields are already substantially sprouted. Trees have all their leaves. Plowed fields provide a dark, wet contrast.

I am looking it all over; I am sitting in my airplane, looking out. To the north, I am struck by the dark charcoal clouds. They are hanging over the fields -- providing even more enunciation of color, dampness, wetness, nature. 500 feet off the ground; perhaps a little more. Occasionally my altitude wanders lower.

The clouds are like slashes of charcoal across a matte paper.

It has rained heavily. A creek is roaring between its banks -- all waters are thick brown. A bit of foam dances up to one bank, but somehow is repelled away. The vision recedes behind me.

I cross the Kansas turnpike. I see a plaza between the lanes. Cars can pull in; get gas; eat at the McDonalds, and go on their way. I wonder who is looking up from the cars, and what they think of my airplane. I'm sure almost all are puzzled: my airplane looks like a dragon.

A few days ago, a trio of deer had run across a field while I circled my dragon above them. Did they see me? I saw them.

I am, in some oblique sense of the word, wasting time.

I find myself once again flying over my friend Terry's home. I don't see his truck; I do see his airstrip. The airstrip is oddly hidden, because of the depth of the grass. (Terry, it needs to be mowed.)

Glancing at the gas gauge, I see 60% fuel remaining. Lots of time to continue to waste.

I can feel a bit of vibration coming up through the heels of my shoes. I've not noticed it before. Like many other pilots who've mused over an odd vibration or sound, I start to think about what could be wrong.

Nothing. Nothing is wrong.

Looking south, I can see 30 or 40 miles to the horizon.

Looking to the north again, the sky is a little hazier. The north horizon is not nearly as sharp as the south. There is more humidity in the air.

An odd thing happens: it starts to rain. Just lightly; but enough to patter the windshield. The doors are not installed on this airplane, and even so, I remain dry.

I have my leather coat on. I'm also wearing a stocking cap, noise cancelling headphones, and light gloves. It's a perfect combination. I can feel the wind beating on the sleeves of the coat as they rest on the sides of the fuselage. My torso and head stay in calm air.

Now I'm even more relaxed: I've pulled my feet off the rudder pedals. The airplane now moves wherever I want it to using just the control stick.

Above the clouds, the sun is shining. Below the clouds, there is ample evidence of the sun and its working: green-ness; creeks; fields; rain; cool flyable air; much more.


Chapter Two: Technicalities

The Belite uses a 5 gallon tank. The purposes of my flight today was to verify instrument functionality and to also nail down fuel consumption. We I flew the plane for exactly one hour and then measured the reserve. I had 1.6 gallons of fuel remaining.

This means that the Superlite fuel consumption with a Hirth 50HP F23 engine @ 5800RPM is about 3.4 gallons per hour. This allows 1 hour and 25 minutes from full to dry tank. Based on a cruising speed of about 60 mph, this gives a reachable radius of about 75 miles in calm winds. I may be able to improve this a little; I've ordered a cruise prop to go with my engine.


Chapter Three: Crosswinds

Our airstrip is 2600 feet long and about 75 feet wide. Beyond each side is an ample unmowed area.

A few days ago, we had a very blustery crosswind.

I looked at the runway a little differently. I walked across it, and picked up some grass. Tossing it up, and looking diagonally backwards, I saw a new runway, constructed by landing on the existing runway diagonally.

"I know what you are doing," said Doug, who runs his small business out of a hangar close to mine and had walked up behind me.

Doug practices whenever possible in one of his helicopters (he's a dealer). He understands the importance of practice, and he saw that I was trying to increase my practice time by overcoming the crosswind blues.

Comfortable with my new 'make-do' runway selection, I took off into the sharp crosswind. I started making circuits around the pattern and the field, re-creating the new pattern.

My new pattern works beautifully. I land without event, diagonally across the existing runway. I take off again. I land in some slightly taller grass. The feeling of moving through the grass on touchdown is ... I struggle for the right word. Great?! Wonderful!? Smooth?? These are not the right words.

There is no adequate word. Landing in the taller grass makes me feel like an adventurer. I don't know how to put that into one word.

This reminds me of when I landed in the flint hills, nearly a year ago. I remember the flow of the grass in the wind, and the feeling of gentleness, as my airplane settled into the thick grass on touchdown.

I take off and land again. Each landing builds confidence.


Chapter 4: El Dorado

The lineman at the El Dorado airport can't believe his eyes: He's never seen a plane as small as mine. We full my gas tank up with 100LL. Total bill, about $8.

Smallest plane he's ever seen; smallest gas sale ever as well.


Chapter 5: Instruments

I occasionally glance at the instruments on the panel. I like what I see! The clouds have completely blocked the sun; I flip the switch over to the 'dim' setting. The LEDs in the panel have a soft glow.

I roll the plane into a turn to the left; the turn gyro shows the turn. I note that my trim tab on the rudder is not quite set correctly: the slip indicator shows a constant 'one dot' slip to the left. I see that I have 30% of my gas remaining: perhaps it's time to land. I've throttled back and the airspeed is showing 55. All is well.

These instruments provide a sharpness about the condition of the airplane: I know my range; I know my speed; I know if I'm straight and level; I know how I'm doing. I like what I see.

I look back at the ground. There is so much green, and so much sharp definition between fields, prairies, creeks, horizon, and clouds.

I can't wait to fly again.

What altitude did James reach in the Superlite???

Today was an extraordinarily beautiful day in Wichita. Light winds; blue sky; puffy cumulus. The airport was buzzing: two helicopters, a tow plane, at least two gliders, a C182, a Aeronca, and the Belite Superlite Sun N Fun winner.

I wanted to test some instrumentation; buzz a friend's house (with his permission); and test fuel consumption in the Superlite. Also, I wanted to climb a long ways up and see what the world liked like.

All successful. The icing on the cake was throwing a roll of toilet paper at my friend Kevin. (A couple of hours later: somehow it reappeared on my front lawn.)

Even though it was a T-shirt day on the ground, I wore my leather coat in preparation for much colder weather up high. When I got up there, I loitered over the gliderport for a long time. I shot video of KAAO (Jabara airport) off in the distance; and although I did not have a true altimeter with me, the video says it all. Very chilly.!



If the blog video won't open, it is also posted on youtube:

http://www.youtube.com/beliteaircraft#p/u/0/peTwoxkIxg0

How high was I?? I'd appreciate your guess.... The Jabara runway is 6101 feet long!

Please place a guess in the comments. Thanks!!

Pics of new avionics while in flight

This will be a short post. I went flying tonight for about an hour in the Belite Superlite Dragon. I wandered near Augusta to try and find Terry's strip -- sorry Terry! Didn't bring a GPS and couldn't find it. Turned around and headed back home.

I took some photos of my new panel while in flight. You can see that the inclinometer (ball) is centered, I've got gas in the tank, the volts are about right, my turns aren't too fast, and I'm about 800 feet off the grand.

I'm having a little trouble with the CHT/EGT gauge -- hopefully I'll have that squared away in the next couple of days.

Did anyone see the dragon fly overhead?

Belite Receives Sun N Fun Grand Champion Ultralight Award

The Belite Superlite, dressed in Belite's new Dragon paint scheme, was given the honor of "Grand Champion Ultralight" at the 2010 Sun N Fun airshow. The picture shows James Wiebe, CEO of Belite Aircraft, receiving the award from Sun N Fun official Leonard Kress. The Superlite's new featherweight panel was noted as being a key feature that caught the judge's eyes.

Sun N Fun is an annual aircraft fly-in and airshow, in its 36th year. Attendance in years past has been about 160,000 people, with 4,500 planes flying into the event. The event is busy with aircraft 'movements', logging 40,000 to 50,000 movements in a typical year.

Pictures of the Superlite may be found here .

More pictures may be found here .

And a very nice takeoff video of the personal flying dragon may be found here.

Featherweight Avionics

Gene and I have made several panels for a variety of our aircraft. They were a mixture of basic instruments: airspeed indicators, altimeter, engine gauges, inclinometers. Basic stuff.

I'd run into a few problems with instruments breaking; also a few problems with inaccuracies. I was tired of weight. I started to think about ways to improve that panel. My 30 years of experience in electronics kept nagging me: I just had to develop some good, inexpensive, state of the art instruments.

A lot of very good companies produce fantastic, expensive stuff. Almost all of the direction of the industry has been towards more integration and more expense.

Why not break that trend?

Why not design basic electronic instruments that replace old fashioned steam stuff, that cost less, that works better, that weigh about a dozen grams, not a dozen ounces or even one or two pounds, and that more quickly alerts (using bright LEDS) to marginal conditions such as low fuel or redline speed? How about instruments with no dials to twist?

Well, that's what I did.

We introduced 10 new instruments to the market. I won't pick at the details of each here (see our avionics page for details). I'll just mention the key points of one of them.



Let's talk about our Turn Rate Indicator:

1) It truly has a solid state gyro in it, and it's incredibly sensitive.

2) It's designed to show a standard rate turn. And several other turn rates.

3) It uses different colored LEDS to quickly show when a turn has begun.

4) The LEDs are bright, easily observed in a bright cockpit.

5) You can see them with sunglasses on, even polarized sunglasses (unlike many LCD screens.)

6) And unlike mechanical gyros, it's inexpensive (about $150).

7) And also unlike mechanical gyros, you can buy it in a tiny box (3 x 2 x 1 inch) which you can velcro to any panel. It runs off an enclosed 9v battery for about 14 hours.

8) Or you can buy it with a standard 2 1/4 inch cutout bezel.

9) Or you can buy it with an even smaller 1.75 inch square bezel.

This is how we approached the design of each of our instruments: Lots of installation and use options, bright LEDs, simple operation, really low costs. Great for experimental, homebuilt, patch flying, ultralights, and perhaps a few other markets as well. (Helicopters? Yes. Gliders? Absolutely.)

My daughter Jennifer prepared a great video demonstrating the Turn Rate Indicator. You can see the video here. If that doesn't work, go to belite's channel on youtube and you'll find several more of our avionic and flying videos.

Even though the concepts are simple, the electronic technology has been a tough at times to tackle. In order to protect the work that has been done, we recently filed 9 patent applications on our technology. As a result, our designs are 'patent pending', which is a great thing as well.

The entire instrument panel pictured at the beginning of this post weighs about 12 ounces. That includes the basic metal plate, and all of the instruments. This is one of the developments that continues to ensure that our aircraft are the best and that our avionics (and aircraft) customers have the easiest to use, lightest, least expensive and most comprehensive goodies in the cockpit.

I appreciate your feedback. I was given several great ideas for additions to this new product line at Sun N Fun -- we'll work on some of them and hopefully show even more avionics at Oshkosh. In the meantime, this is great new stuff.

Finally, these avionics are 'on sale' for this first week of their introduction. You can order them with discount code SUN10 on our webstore through the end of 2010 Sun N Fun, (april 18) and this will give you a 20% discount!

We are also intent on adding distributors, both here in the US and overseas. Interested? Let me know.

Details on the new Trike

Our four aircraft news announcements have been posted. Today, I'm going to add important details on the new redesigned Trike.

First of all, it's beautiful. Based on customer feedback, it's much nicer than our original Trike design. It's also less expensive. It's also more configurable --- you can easily convert it from Tricycle to Taildragger to Tricycle gear.... whatever you're feeling like.

We're bringing our Trike demo plane to Sun N Fun.

Here's the cost details for our demo plane:

Basic Taildragger model, Ready to Fly: $24995
Trike Package: $1500 (add to ANY kit or ANY RTF airplane)
Carbon Fiber Wings: $3100 (this is a reduced price, details in another post)
Engine Swap: $1600 (this swaps the MZ-34 for the MZ-201 45HP engine)
Propeller Swap: $600 (this swaps a Tennessee wood for a 3 blade composite)
Instrument Panel UPGRADE to NEW AVIONICS: $0

TOTAL $31795 as configured

A basic Trike starts at $26495, RTF. ($24995 + $1500 Trike Package)

OK, now you're probably wondering: what do you get in a Trike package??

Here's the answer:

-- front gear tube, prebent from 1 5/8 chromalloy steel
-- front gear brace, prewelded using chromalloy steel
-- left and right .190 prebent / machined aluminum gear arms
-- delrin nylon machined blocks (4 pieces)
-- bolts / nuts
-- front modifications to fuselage -- carrier tubes prewelded and brace patch prewelded;
-- main landing gear mods to fuselage -- horizontal and vertical
reinforcements to fuselage for new gear hardpoints
-- disc brake packages (2)
-- machined aluminum disc brake mounts (2)
-- disc brake cables
-- heel brake weldments

This means that you can change a Trike back to a Taildragger (you may have to make a new exhaust for this swap...)

We put carbon fiber wings on our demo plane, because the weight savings allowed us to use a bigger, heavier MZ-201 engine.

You'll notice in our flickr photos that the Trike also has our new instrument panel with our new Avionics that we designed!! This new panel weighs about 10 ounces with basic 4 instruments installed: EGT/CHT; Inclinometer; Air Speed; and AGL altimeter. The LED displays are brilliant and easy to see, even in direct daylight. The weight includes the metal panel, which is gorgeous, and the instruments.



The Trike is the first real ultralight that's also a real airplane.!!

On the eve of four announcements

It is Sunday evening; my wife and I have comfortably settled into our rental home in Lakeland Florida. Sun N Fun starts in two days. Tomorrow, we're sending out four news releases.

We're exhausted. Our staff and us have been working nearly around the clock for the last couple of weeks, trying to get everything ready and buttoned up for the show.

Most of my time has been spent on the development of a suite of avionics -- you'll be able to read about them soon enough. I've already concluded that once you fly with our new air speed indicator, you'll never use any other air speed indicator again. Ours is designed from the ground up for slow experimentals and ultralights. But it's just one of ten or so new avionics we're introducing, and it is by no means the coolest. Enough said on the avionics, or I'll spill the beans prematurely.

I asked for feedback on the Trike several weeks ago. You responded; and we completely redesigned it. Take a look at the pictures which have been posted on flickr
and you'll see that the Trike is now identical to our conventional taildragger model. And you can switch back and forth easily!

The Trike pictured is powered by a MZ202 engine with 45 horsepower. It uses carbon fiber wings, and tips the scales at about 250 pounds. Amazing.!

That's all for now.

See you at Sun N Fun in two days!

James