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Howdy, Model Airplane News! My name is Anton Kolomiets - I am the team captain of the Texas A&M AeroDesign team. The team consists of 7 Aerospace Engineering students from Texas A&M University in College Station, TX - our challenge is to design an RC aircraft that is capable fo lifting as much weight as possible, while being powered by a stock, unmodified OS .61FX engine, being able to take off in 200ft, land in 400ft, and have a wingspan+height+length size not to exceed 175 inches. The record wight lifted so far is around 32lbs - we hope to beat that record! This is an ambitious goal, but my team is one of the most skilled and talented that i could ever ask for - I do believe this small-town team has what it takes to do something bog this year. 

We will be keeping a record of our design "flow" - our ups, our downs, our successes, our failures - exclusively through this blog. Check back, as we plan to post updates at least on a weekly basis.

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POST 1 - October 14th, 2008.

A month ago, the 7 of us decided that we want to pursue a project a bit out of our day-to-day lives. The Heavy-Lift Competition through the Society of Automotive Engineers gave us the perfect opportunity. We created a team website (aeweb.tamu.edu/sae_design), opened a team bank account and registered ourselves to become a fully legitimate competition team.

OUR DESIGN IS BORN

Before we can really begin working on a tangible aircraft design, we have to know our limits and constraints. The rules for the SAE competition say the aircraft must be powered by a fully stock OS .61FX engine, a "production" consumer propellor, 10% nitro fuel (provided by the organization) - no tuned pipes, no engine mods. Clearly, the engine will be one of the areas that limit our design posibilities - first of all, the OS .61FX was not designed to carry a load in excess of 30lbs. It flies 7-8 lb aircraft with ease, but a heavy-lift design will definitely have to be designed around our limited avaliable power. Also, to lift a heavy weight, our aircraft would have to use a high-lift airfoil which is inherently draggy.

Our first task was to test our engine's abilities. We designed a thrust stand using some wood we had. The engine itself mounted to two aluminum L-beams that were in turn mounted to another wooden mount. The idea behind this stand was to allow us to test our engine's thrust output using various props so that we could gauge which prop gave us the most thrust at full throttle. To allow us to actually get a quantitative thrust meaurement, we built a rail and roller system to allow our engine to slide back and forth along the test stand. The engine and engine mount were secured to the test stand with a digital fishing scale.

To test the engine, we ran it several times, each time using a prop of different size, shape, composition, profile, pitch, etc while keeping our mixture settings constant. We took a good deal of thrust readings for each type of propellor used - each time we take a reading, we would advance the throttle on the radio by 1 click. By counting ou the number of clicks the thottle stick has between 0 and 100% wide open throttle, we were able to get thrust readings per percentage throttle settings (our data and graphs in the long run were all plots of thrust vs. percentage throttle). We were only really interested in the maximum attainable thrust with each propellor, but also took the throttle to thrust curve into account when deciding which propellor will be used in the competition.

The tests showed us that our best prop choice was an APC that allowed us to reach a maximum thrust of around 4kg (just under 9lbs).

Using these figures, we know the maximum power we have available to us. This will come in very useful later on in our project when we look at our total airframe drag and the total weight we can lift and still make it off the ground. 

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post 2 - October 16th, 2008

Our group met with one of our professors to discuss possible airfoils we can use for our aircraft's wing. The SAE competition limits the allowable wingspans for competition aircraft, so we were originally thinking of a biplane design using a regular flat-bottom (trainer-like) airfoil for both wings - this would allow us to almost double the lift we can get off of the wings without increasing our overall wingspan. This design would be beneficial in many ways...  overall, the increase in lift we would get off of two wings is an obvious plus. Aside from that, the aspect ratio would go up with two wings - at the same time, wing loading would go down. The incresae in wing area would allow us to add more control surfaces such as flaps and ailerons, potentially giving us better control of the aircraft in all flight regimes. A biplane design could be slowed down very well for landing as well and should handle the additional weight better.

The downside of a biplane design is the added drag on the aircraft, added weight of the second wing, and the degradation of aerodynamics due to the interaction of the two wings in flight...

We are working out some figures comparing the benefits and losses with using a biplane design as opposed to a single, high-lift wing. Apart from that, we are running some simluations  on various airfoils to help us visualize the pressure, lift, etc of each airfoil
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November 4th, 2008

We divided our team into a few key technical groups, each working together but ultimitely responsible for their own part of the project. The various groups are Stability and Control, Aerodynamics, Structures, Propulsion and Performance, RC integration and avionics, and Documentation.

Aerodynamics:

Our team had initially decided that we were going to try and use a NACA 4-series airfoil for our design. One of our professors provided us with a computer program that would allow us to determine various aerodynamic characteristics of different airfoils. The two aerodynamics guys ran fifteen different NACA airfoils through the system, gathering data for the coefficients of lift, drag, and moment, as well as how far down the wing the flow separated. As expected, as the percentage of maximum camber rose, so did the lift coefficient. With this rise however, also came a rise in the coefficient in drag. We then had to determine the most effective trade-off between these two values. After looking at the data and weighing the pros and cons of each airfoil, we decided to go with the airfoil that we thought from the beginning would be the best. These simulations gave us data with which we could more effectively base our decision on
The NACA airfoils seemed to be the best for our purposes of this project. It gives a decent lift distribution
and a respectable Lift to Drag ratio. The lift distribution isn't exactly ideal. The more
elliptical the lift distribution of a wing is, the less of induced drag it produces. Since induced drag increases exponentially with airspeed it can be neglected with our design - our aircraft will be specificallybuilt for low airspeeds and high lift (due to our limited power available and relatively high wing loading requirements). An eliptical lift distribution can be obtained through a number of ways, one of which is tapering the wing to the edges. We decided against the tapering because our wing simulations showed that at our estimated max flight speed, the effects of induced drag are minimal. With no need to taper, we can build a straight "trainer" style wing.This also allows for a quicker and easier assembly of the wing and opens the door to the possibility of maybe building a few of these wings for flight testing.

Structures:

We have started our initial design of the wing structure. The spar of the wing is the backbone of the aircraft. This component carries the full weight of the payload and must be very strong. We have build some computer models to simulate our design in flight and have done sevaral hand calculations to find the strength. We are also current working on building a test spar to load and break to find the breaking strength. Hopefully our test data will be fairly close to our calculated strength. We have gained access to a materials science lab at our University - there we will be able to do bending and rigidity tests on our spar design and hopefully come up with a way to carry all this anticipated load without having to resort to heavier materials such as aluminum. Pictures of our simulations and overall wing design can be found on our team website:

http://aeweb.tamu.edu/sae_design/photos.html

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November 14th, 2008

We have been throwing around some ideas on how to construct our wing spar. For this particular application, we have to keep the wing (and entire aircraft) as light as possible, while building it strong enough to handle our anticipated load (in all flight regimes). We thought an aluminum spar would work best, but that would have been a particularly weighty option, although it would have provided more than enough strength.

We came up with a bit of an "unorthodox" spar idea. We built a test spar, complete with webbing, etc and ran a few mathematical models on it. After those had been completed, we ran a physical test in which we simulated the max forces this spar would ever encounter in flight. The spar setup passed all of our tests with flying colors - it is incredibly light, considering its strength and durability. We think it will work nicely

Also, we have made some arrangements with our university's architecture department. They have a laser cutting machine that we could use to cut out ribs, sheeting, etc for our wing prototype. We hope to have a first batch of ribs cut out within the next week. With any luck, we should be able to start construction on the aircraft within the next few weeks.

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November 27, 2008

Our first batch of ribs have been laser cut - they look great! Most of what lies ahead of us will be grunt work. We have most of the materials together to put the wing together, so as soon as we finish up our last batch of projects for the University, we will try to knock out the wing construction. The fuselage is in its final stages of design. We have pictures a few preliminary pictures up (from Solidworks) on our team website at aeweb.tamu.edu. Basically, the fuselage is where we hope to save a good deal of weight in the overall design. The wing is built relatively light, but we definitely didn't want to cut any corners when it came to the wing. This plane will have to hold up a good deal of weight, both on the ground and in the air, thus the wing is over-built by a decent safety margin. The fuselage, on the other hand, is buit as light as possible and serves mainly as a means to transfer the thrust from the motor to the wings. We could achieve this by building our "cargo bay" straight into the wing itself. It is supported mainly by a few plywood bulkheads and a steel support system built right into the wing spar. The landing gear was another concern to us. We couldn't simply bolt it onto the fuselage like on a convential RC plane since we had decided on a minimalistic approach to the fuselage. The landing gear was design the work with the cargo box itself and is also ultimitely supported by the wing spar and cargo box alone. We will have a few pictures up when we get closer to the fuselage construction to try to explain our concept a bit better.

According to our calculations, approaching the construction this way saves us a good deal of weight overall. The next week or so will be devoted to wing construction and to finishing the design work for the fuselage. After building the wing, we were hoping to use a stock trainer fuselage to fly the wing and get some real-world data on the wing's stability and performance in flight (I've never been a huge fan of relying solely on simulations for aircraft design). 

We will keep updating our website with pictures and video as it becomes available! If anyone has a stock trainer body that they wouldn't mind getting rid of, we would be happy to take it off your hands!!

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December 4th, 2008

Our wing is almost ready to go! we have it framed up with spar, leading, and trailing edges installed. So far so good!! We will be posting some pictures on our team site shortly, so please feel free to check http://aeweb.tamu.edu/sae_design/photos.html for more.

We plan on covering the wing and the fuselage in Ultracote. If all goes well, the wing will be done before our final exams (next week) and we will have started working on our "testbed" fuselage. HItec RCD has gracioulsy donated servos for our project, so we hope to start installing the aileron and flap servos as soon as we get the wing covered. There is a small concern that our current wing design will need to be expanded to carry all of the weight we hope to carry. This we won't be sure about untill we actually try the wing out in flight.

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December 11th, 2008

We're done with the wing!! We finally have it all sheeted and completely sanded.

http://www.aggiesigmanu.org/aerodesign/files/files/Construction%20Pictures/DSCN0843.JPG

Tomorrow we will make a trip to the hobby shop and pick up some ultracote - hopefully we can have it covered and have the wing servos installed by the end of the day. We have started to work on our testbed fuselage. It is quite basic in design - it builds on the concept used by SPAD and combat planes and uses a single square aluminm beam for the structure. We will mount the engine mount and engine directly to the fuselage and give it a basic landing gear system. The whole idea behind this fuselage is to make it as simple and as indestructable as possible. This way, we have a chance to fly our wing and let our pilot get used to any bad tendencies it may have. Our official design uses an all-flying tail, but the test bed will go with a simple trainer tail section.

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December 14th, 2008

The testbed fuselage is nearing completion. Basically, we used an aluminum beam as the backbone of the testbed fuselage. Attached to the beam are all of the electronics that control the plane, the fuel tank, and all controls. Attching the wing is a bit of a challenge, as the aluminum beam we are using is only an inch wide at the point the wing is attached. We went on a bit of a tangent with actually builiding this fuselage - we had planned to use a trainer fuselage with the usual, common trainer plane tail surfaces. The design we picked in the end was more of a SPAD or combat-type of fuselage than a trainer.  It is a bit heavier than the trainer fuselage would have been, but we believe it will be easier to maintain and fly in th long run. Apart from the prototype wing, we will also be using a prototype all-flying tail - the same one we plan on using on our final design. There are a few concerns that this tail will be very "squirrely" and sensitive in flight. we will be using a good deal of dual-rates in flight. Hopefully, this testbed aircraft will give us some real-world data on our wing and tail section. We hope to have this plane flying by the end of the week! keep checking for updates!

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December 19th, 2008

SHE FLIES!!! We had our first flight with the test rig yesterday and we learned quite a bit about our wing and controls setup. First of all, we were way off on our CG and aerodynamics center calculations. Our particular airfoil has a pretty decent moment in the air that we had to overcome with nice big control surfaces at the tail. The first flight was very unstable - we landed the plane and strapped a good deal of weight to the nose area. With all that weight and with the CG movedmaybe an inch forward, the second flight was not quite as dramatic - the plane became much more responsive and easy to fly. Apart from the balance issues, we found a few more aspects of our original design that will have to be modified before the next flights. Our ailerons were too small and were almost ineffective at slow speeds - this plane tends to float quite a bit on landing due to the "built for lift" wing. At higher speeds, the ailerons worked better but were still quite sluggish. Our rudder design might need to be ammended as well - again, at slow landing speeds, we really need something to grab the air a bit better. Overall, the first few flights were a success!! With our all moving tail, we can get some pretty exciting aerobatics out of the plane.... of course, that's just us having fun with it :)

We will try to change up the ailerons and weight distribution for another flight today, weather permitting... I will post a link here with some in-flight videos and pictures as soon as they become available

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December 20th, 2008

We put another test flight on the plane yesterday. First of all, we fixed some of the issues we had discovered during the first flight, hoping to zero in on a "sweet spot" for our plane stability and control-wise. We increased our aileron chord by half an inch, which actually has a pretty decent effect on the overall area of the ailerons. Also, the original design had a flaw when it came to the aileron design itself - the hinges we decided to use for the ailerons were a bit big for our application, so there was a relatively large gap between the end of the wing and the ailerons. We sealed up the gaps on each wing with a strip of Monokote about 2 inches wide. We did the same for the rudder and vertical stabilizer gap. Apart from that, we changed out our flight battery  - the one we had before was rated at about 1100mAH and the new one is rated at 2400... basically, we just did this to help us out with the CG of the plane, since the 2400mAH battery is quite a bit heavier.

It flew much better this time! the increase in aileron area helped out the controls quite a bit, but we might still have to go back and change them up again before settling on a final design. We practiced some stalls, touch and go's, and began adding weight little by little.

Unfortunately, one of the strips of monokote we had used on the left wing to seal the gap came up in flight - it was stuuck up about an inch into the airflow and acted as a spoiler over the left wing....  the plane lost lift along almost the entire span of the left wing and spiraled in to the ground. Surprisingly, the damage to the test rig was minimal! We lost our Tru-Turn spinner and the beam we used for the fuselage is a bit bent, but the wing, control surfaces, engine, and electronics are perfect. We should have it fixed very soon.

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January 14th, 2009

The team is finally back together after a long break for Christmas and New Years! We spent our down time working on the team design report. For the past few days, we have been working hard to finish construction on the final competition fuselage and a second wing, just in case we have an accident anytime between now and the competition date. As of right now, we have the fuselage framed up and almost ready to be covered. The landing gear arrangement on our aircraft is a bit unorthodox. It is essentially a tricycle landing system, but the main gear is attached to our payload in a creative way to keep the payload weight off of the fuselage at all flight regimes.  It is finally starting to jump off of the computer screen! After construction is complete, it's off to the flight line for us!! We have to flight test the full aircraft with the competition fuselage and payload, to make sure our assumptions and design actually does teh trick in real life.

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February 10th, 2009

Construction of the final model is done! It looks so nice, I'm honestly a little terrified about the first test flight of the finished product. Thisthing is our baby! We are framing up a spare wing, tail sections, etc, just in case something goes wrong on the first flight. At least tat way we will have a nearly-complete wing and tail section to replace on the aircraft. Our unorthodox landing gear system is giving us a bit of trouble - it's proving to be a little harder to put together than we had anticipated, but all in all, we should be able to get te kinks worked out relatively soon.

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March 1st, 2009

Due to unseasonably windy and rainy weather, we have yet to get the final product in the air!! We are putting the rainy days to good use by continuing to work on "spare parts" in the hopes that if we go down, we will not necesarily be forced out of the competition. let's hope next weekend gives us a little more to look forward to than the past few weeks have....

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March 24th, 2009

As optimistic as our last post was, mother nature doesn't seem to be on our side. Each of the past few weekends have either been rainy or the winds were howling around 20 knots ! The competition is NEXT week, and our plane still hasn't seen the sky! Our optimism is starting to turn to desperation - as risky as it may be, this weekend looks like our last chance to get a test flight in before the competition, so no matter the wind, we will have to try it out. Wish us luck - we'll definitely need it this weekend!!

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March 26th, 2009

While we wait for the clouds, rain, and wind to go away, I'd like to offer a bit of an aside on this design project. When we started designing and planning out this project last year, I could never have imagined the kind of experience it would turn in to. I have heard the stories the seniors at Texas A&M have shared about their experiences with the senior capstone project of designing and building an aircraft, but it's a completely different animal when you experience it first hand. We have spent countless hours writing reports, working on computer models, and of course building this plane, but looking back on it, I can honestly say not a minute of it was boring or wasted. It was always exciting, just to see how what we learned in class can be applied to a real, tangible aircraft. The team started out as a group of friends, but we have grown closer over the past months. This has been a labor of love for us from the beginning and I am amazed to look back on the experience and see exactly how much we have learned, how much we have tought ourselves, and how much we have discovered about Aerospace design from this simple, ugly little airplane.

Even if we don't do well in the competition (knock on wood), I have already taken away so many new experiences from this project, that it's already been all worth the struggle. I'm taking away lifelong friends and the pride that comes with an engineering success story - that on it's own is amazing.

I would highly encourage any aerospace students out there, or anyone interested in learning about aviation, to try your hand a project like this. It's one thing to learn from a textbook, but it's a completely different experience to add a third dimension to your education by actually putting iot to use! The feeling of watch the plane you've designed and built take off and fly for the first time is indescribable!

Final test flight this weekend and we're off to Atlanta! Stay Tuned!

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March 28th, 2009

A cold front came through last night - skies are clear, but the wind is howling at a sustained 17 knots gusting to 28 knots. The weather channel is saying tomorrow will be clear and nice all day  - here's hoping

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March 29th, 2009


The sun came out, winds variable out of the south - we finally got to take her up today!! After some adjustments and a good deal of trim, the plane is flying relatively well. We tried our luck with some weight as well - 5 lbs of payload took a bit of a longer takeoff run, but it got off the ground and seemed to perform as expected. One problem did arise during the flight - our weight attachment system uses regular nuts to hold the weights on to a couple threaded steel rods. These nuts would tend to vibrate out of position during flight, allowing the weights to shift around a bit. We replaced them with steel/nylon lock nuts which we hope will take care of the problem.

half of the  team will be flying commercailly to get to Atlanta, while the other half will be driving the whole way (16 hours), loaded down with flight gear, replacement parts, luggage, etc. 3 days to go!

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April 4th, 2009
  
the first day of flight was today - i don't think i've ever been so nervous in my life. The first round of flight was our empty-weight flight  - it went well! the plane was stable and very responsive. On the second flight, we decided to add 7lbs of payload but we couldn't seem to get it off the ground for the next few rounds  - our landing gear system gave us a lot of trouble in that the nylon wheels we had been using for the test flights had very little traction on the asphalt runway of the Cobb county RC field. In the end of the day, we changed out the nylon wheels with regular rubber wheel and we were able to easily lift our 7-lb payload

We are confident that we will be able to carry a weight closer to our goal tomorrow, assuming the weather cooperates (thunderstorms are predicted as of this morning).

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April 6th, 2009

The final day of flying at the aerodesign competition brought out some unanticipated problems in our airplane design. The first flight attempt of the day was made with a 12-lb payload (total flying weight with additional payload: 24lbs) - the plane was able to take off in less than the allowed takeoff distance, as we had anticipated, but as it started to climb, it was evident that our ailerons did not have enough authority to provide adequate control. our oversized rudder and  elevator, on the other hand, were more than responsive enough. Unfortunately, our initial turnout from runway heading was made at too low an altitude and the plane suffered a "gentle crash" into a hillside. Our landing gear and payload support system were damaged, but we managed to rebuild the landing gear and fix up the payload supports before the ext round of flight. 

On the last round of flight, were able to carry roughly 11lbs of payload (and it's still in one piece!)

Although we didn't win the competition, the entire teams has come out of this with a new appreciation for what we do in class and read in our textbooks on a daily basis. We have all learned incredible things from this project and from each other - winning couldn't possibly have made this weekend any more exciting. Here's hoping that we can do this again next year!

Thank you to everyone who has offered us advice and support throughout this project! We couldn't have done it without you! Blue skies!


Pictures are up and can be found here :

Design, building, initial testing, and drive to Atlanta:

http://www.facebook.com/album.php?aid=2707852&id=8361984&l=4629a73107

First day of competition:

http://www.facebook.com/album.php?aid=2714181&id=8361984&l=4fc6398bc6

second day of competition:

http://www.facebook.com/album.php?aid=2714201&id=8361984&l=02d3dbe908

enjoy!!

Anton Kolomiets