Flight Troubles?

shorti96
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Flight Troubles?

Postby shorti96 » August 31st, 2009, 4:49 pm

Hey guys, I just can't seem to get the hang of building and flying my model airplane. I've tried all of the great ideas you have but can't seem to get it just right. Usually my planes just go straight for about 2 seconds and then they crash on the ground. I've also tried adjusting the area in which I fly my planes. can anybody help me PLEASE!!! ;)
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Re: Flight Troubles?

Postby GitItWright » August 31st, 2009, 5:18 pm

OK. There is a lot to look at here. First, give me the basic dimensions of motorstick.. length, and cross section dimensions. Second, How much does it weigh? Third, what crooss section size is the motor you are using?

When you launch does the airplane ever climb? Does it ever fly level? Does it fly better on half the power? Answer those and we can proceed.

Good Luck
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shorti96
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Re: Flight Troubles?

Postby shorti96 » August 31st, 2009, 5:23 pm

Well first of all I haven't actually started building a new one for 2010 yet but all of the ones I've ever built have done the same thing and I don't know where to get started this year.

The planes never really started climbing but they did stay level for a few seconds but only twice ever.

If you can help me get started that would be great :mrgreen:
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Re: Flight Troubles?

Postby andrewwski » August 31st, 2009, 6:47 pm

There's a lot that it could be. Without further information, it could be almost anything.

First, have you tried adjusting the position of the wing on the motorstick? This can often be a problem if your wing is too far forward or too far back. If you can afford the weight of a wing saddle, it can be very helpful for your first plane, as it allows you to figure out what different positions of the wing will do to the flight of the plane.

Have you attempted to change the angle of attack on the wing (how high the front is in relation to the back)?

If the flight is stable, i.e. a gentle glide, your motor may not have enough torque, however if it dives, then something isn't trimmed correctly.

Too much torque would also be a problem if it's causing the motor stick to bend.
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Re: Flight Troubles?

Postby jander14indoor » September 1st, 2009, 3:40 am

First, don't worry about this year or last years rules, problems and solutions are the same. Its still a rubber powered duration plane.

If you haven't flown more than a few seconds we really need to start with the basics and need to know more than it crashes in two seconds.

What design plane have you built and tried to fly? Was it a kit, which one. A design off the internet, which one. Own design, please give a detailed description. This is critical because you may be trying to fly something that just won't work and anything we say won't help.

Once we know your design, we need to know more about the execution. How well built, weight, "straight", center of gravity, control settings, etc. Those have to be close to right to get even a good design flying.

From there we'll need to know something about winding technique, rubber, etc. But frankly I don't see those as the problem, you should be able to get a good slow glide if the above is correct even with bad rubber or poor winding.

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Re: Flight Troubles?

Postby shorti96 » September 1st, 2009, 1:52 pm

okay thanks when I start building I can't get you all some more info but right now, my school hasn't even started to meet for sci oly but we probably will soon so I'll post more info then thanks :D
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Re: Flight Troubles?

Postby Cyrus_D » September 7th, 2009, 7:13 pm

Currently I don't have a problem but a friend of mine usually does. He builds a 14+ cm wings with mylar, and half of the test flights he fly's stall. Is this a reason because of it is getting too much lift? Or is there maybe some other explanation.

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Re: Flight Troubles?

Postby jander14indoor » September 8th, 2009, 5:07 am

No such thing as too much lift, but it can come at the wrong time.

To interpret the stall, we'll need to know a little more about it.

Does it only occur at the beginning of the flight and only when he/she starts really adding on the winds? If so, you have a poweer stall, probably need to add some down thrust to the prop. Sometimes lowering the rear edge of the stab helps, but try that second if the rest of the flight is OK.

Does it occur repeatedly thoughout the flight? If so, your CG is probably too far back. These wide wings seem to like a more forward CG than the narrow ones, relative to chord.

Does it occur only after the haflway point in the flight? Possibly to rearward of CG, though not much, or possibly too much up elevator, try lowering the rear edge of the stab in very small increments.

Does it only occur after bumping into things? This ones trickier, your stability margin is too low and you'll need to change things in combination. Move the cg forward slightly and the tail back.

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Re: Flight Troubles?

Postby blue cobra » September 20th, 2009, 7:27 am

I propose this thread be used for any people who need help with their individual flights. Then we don't end up with 50 of these :lol:
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Re: Flight Troubles?

Postby shorti96 » October 19th, 2009, 12:26 pm

ok then, any way so can anyone tell me exactly what to do or post some designs that actually work??? because there's some designs on th web,but so far none of them have ever worked and I have to start building tommorrow!!! :o
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Re: Flight Troubles?

Postby jander14indoor » October 19th, 2009, 5:45 pm

Start by reading backwards in these note strings and last years archive. No one way to get there so all we can give are pointers.

First, pick a plan.
Many designs on the web work, some need modifying to this years rules, some don't. The Finny-09 by Bill Gowen works VERY well and still fits this years rules I think. It is in the Yahoo group Indoor_Contruction in the files section. You'll have to join the group to see it.
This one is available on the national SO website, not perfect, but certainly capable of 2 min flights. http://soinc.org/sites/default/files/up ... ans2.0.pdf
This is an older plane that flew well, modified to fit this years rules with similar proportions and it will work. http://www.rivard.org/aeromodeling/freeflight.html
Note, all of above assumes you built the plane to max allowed dimensions under the rules and minimum weight.
Most of these plans are missing a key element, the detailed bill of materials that tells what each part should weigh to hit the minimum 7 gm before you build the plane.
What plans have you tried that don't work?

Second gather materials. Refer to the bill of materials to make sure you pick light enough wood to build a 7 gm plane. Random selection just won't work. Note, SO planes do NOT need exotically light wood. None of my demos uses less than 6 lb/ft3 density and most is above 8 lb/ft3. But you do need to select for weight.

Build carefully. Use jigs and fixtures to make everything come out as intended. Again, see the archives for hints and tips. And the National SO page for the Wright Stuff event, http://soinc.org/wright_stuff_b lots of tips there.

Fly, fly, fly.

Jeff Anderson
Livonia, MI

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Re: Flight Troubles?

Postby andrewwski » October 19th, 2009, 6:30 pm

I used these instructions to build my first WS plane about 5 years ago:

http://web.archive.org/web/200806190448 ... ws/ws.html

The original webpage seems to be gone, but thanks to the Wayback Machine you can still get it.

The instructions are a tad outdated, and there's some things I learned to do differently. Mylar is now allowed, you don't need to use Japanese Tissue (although with WS weight allowances, you can use it just fine. It's easier to work with too). You can probably use 1/16" balsa for ribs instead of 1/32" (much easier to work with). Dihedrals are much easier to create by building and covering the wing as one piece, then cutting the outer spars, elevating the tips, and gluing, rather than this method of angled ribs. A two piece motor stick is much easier than trying to create a tapered one. Most builders will use tubes to attach the wing - although a wing saddle is very useful for a first-time builder, let's you see the ideal position of the wing and how different positions make a difference. The Ikara props eliminate the need to shave another prop down.

They are good instructions for starting out though. I think I got about a minute out of that design my first year, with only about 3 days of trimming. I ended up doing WS at the last minute, had 3 weeks between the time I started building and the competition. I'm pretty sure if I had more time to test it, it would be capable of at least 30-60 seconds more without anything other than simple trimming. That is under the old rules of that year though.

You have to change the dimensions to fit the current specs. They're not perfect instructions. But they are a good starting point.
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Re: Flight Troubles?

Postby blue cobra » October 20th, 2009, 8:16 am

shorti96 wrote:ok then, any way so can anyone tell me exactly what to do or post some designs that actually work??? because there's some designs on th web,but so far none of them have ever worked and I have to start building tommorrow!!! :o

Well, your first plane isn't going to be very complicated, so you don't really need a design. If it will help you, of course use one, but it should be pretty simple. Of course I may not be as experienced as some of the others here, but I was in the same place you are just last year, so this is what I reccommend:
1)Wing- Cut out two 40cm sticks out of 1/16 sq. for your leading and trailing edge. Pin the TE down to your building board first, parallel to the edge of your board, if possible. Next, pin down the LE parallel to that at the distance you need for your ribs. I used laser-cut ribs at first, which you can get from Indoor Model Supply. Don't trim them. So now make sure your LE and TE are parallel and squared up and at a good distance, and measure the distance between them. Cut two sticks 1/16 sq. this distance and glue them between your LE and TE at the tips. Next, glue your ribs on (make sure all the Leading Edges are facing the same way). Put two about 1-2mm apart in the middle. Evenly space the rest. Now cover the wing, we've already gone over that part, and induce about a .75 inch dihedral. Add posts, and possibly more supports, and you're done.
Horiz/Vert Stabilizer- I just built this flat, with a peice extending out the front center to rubber band down. Angle the vertical one (the rudder) to induce a turn.
Motor Stick/Tail Boom- I personally used 1/8x1/4 for my motor stick, but a lot of people use 1/8x3/8. The thicker one obviously is stronger. Use 1/8 sq. for the tail boom.

About measuring weights, maybe all my wood just happened to be perfect all year long and I'm about to get struck by lightning twice, but I didn't check, and all my planes came out under 7g. The problem with checking weight of individual parts is that beginners don't know what each part should weigh. Now, weight is very important, but your first plane really doesn't have to be 7.00000g. Maybe your second, but not the first :D . It definitely should be under 7.5g, though.

Hope I could help!
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Re: Flight Troubles?

Postby goblue007 » December 15th, 2009, 11:13 am

I have built an airplane just to get the hang of things untill my kit arrives. The plane curves but doen't climb what can I do to get it to climb and get a good flight?
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Re: Flight Troubles?

Postby jander14indoor » December 15th, 2009, 3:28 pm

Well, more details would be useful. Its hard to give help with so few facts.
How much does the plane weigh. How big is it. How much rubber are you using, what kind? How hard are you winding the motor. How long does it circle without climbing. Please describe a flight in detail.

That said, here's the couple of big generic things I've seen over the years preventing good flights.
Plane is just too heavy. Sorry, only solution to that is to build a lighter plane.
Not winding the motor hard enough! Even with a properly built and trimmed plane it takes 1200 plus turns on a 3/32 wide 1.5 gm motor to fly good SO planes to these rules. WIND those motors.
If your plane is light, you are winding the motors hard, and are getting nice level, but not climbing flight, increase the angle of attack by tipping the leading edge of the wing up or trailing edge of the rear stab up. Make small changes.

Get back to us with details for your flights and we can be more helpful.

Jeff Anderson
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