Helicopters C

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JasperKota
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Re: Helicopters C

Post by JasperKota » October 16th, 2017, 8:09 pm

Ten086 wrote:...Also, after struggling a lot last year with testing rubber bands, I figured I should probably actually like learn about torque...where can you get a torque meter and how do you use one with a rubber band? Again, sorry to anyone who's probably cringing at how dumb I am. I read posts, especially Jeff Anderson's, about how to use a torque meter to compare data and such but I don't even know how to use a torque meter period.....

For lubricating rubber bands, is armor-all considered the best lubricant? I remember something about using hand lotion, wouldn't that be bad for rubber bands?

Is the Freedom Flight kit really doing a chinook design this year? I'm kind of sad because our school's team just like didn't get funding this year because the money isn't for "classroom purposes" so we're frantically trying to raise money for builds, and I feel like it's not possible to be competitive in helicopters without the kit.

Sorry for such a long post.
Armor-all is considered to be a standard lubricant that many people use. I found it to be good, and I've heard that silicon-based lubricants work very well (have never heard anything about hand lotion though). As for a torque meter, I know freedom flight models and laser cut planes sell one, but if budget is a problem you can also make your own from here: http://www.indoorspecialties.com/articl ... 0Meter.pdf Using a torque meter isn't that hard, but a bit difficult to explain in text - here's a video showing using one: https://www.youtube.com/watch?v=_MoozVXuuYY&t=32s As you wind the rubber clockwise, torque increases which is shown by the ticker turning clockwise.

Kits are a good starting point but don't let that discourage you. I'm pretty sure one of the national medalists last year didn't use a kit, and you can definitely be very successful with or without the kit or chinook bonus. Also, it seems like everyone on scioly.org knows what they're talking about, but there's plenty of people who don't (including myself) so don't be afraid to ask questions.
2020 Events: Fossils, Gravity Vehicle, Wright Stuff, Ping Pong Parachute
2019 Events: Fossils, Mousetrap Vehicle, Wright Stuff
2018 Events: Helicopters, Mousetrap Vehicle, Parasitology, WIDI
2017 Events: Ecology, Invasives, Wright Stuff
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Re: Helicopters C

Post by coachchuckaahs » October 17th, 2017, 8:16 am

Ten086:

While the kits are great starting points, you can quite easily build without a kit. It means you have to do some design work, and some more trial and error, but it is so much more rewarding.

Our team must develop contest birds without kits, because our Regionals are in January, and so the availability timing of the kits makes it hard to get a lot of flying. We started building and testing before the rules came out, using last year's rules as a starting point. Obviously we had to change, but that allowed us to get techniques started.

For simplicity, start with a simple x-style rotor with 0.020 carbon rods for LE and TE. Set up for 6-8" pitch for your first build. Make a foamboard or balsa fixture to set pitch and build the rotors. Play with chord, pitch. Weigh sheets of wood at local hobby shop, you will find tremendous variation in weight.

If you build two rotors (you have to), it is not much different to make a Chinook style. Use two vertical rubber motors. If mounted horizontal, then you have the transmission issue, and you still need two pieces of rubber for counter-rotating. Keep it as simple as possible. If you go Chinook, you will need some vanes for stability.

I would start simple with a traditional axial two-rotor system, and then adapt the same rotors to Chinook once proficient at flying the axial.

Like said by others, not all info on forums is good. Maybe mine is helpful, maybe it is rubbish. But don't be afraid to build without the kits.

Chuck
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2018 B WS 2nd place
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2019 C WS Champion
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Re: Helicopters C

Post by andrew lorino » October 17th, 2017, 10:21 am

Ten086 wrote:Hey, so I've been looking through past years' forums and am just very confused in general. I did the event last year but was Not Great because I was just trying to get my helicopter to actually go up, so I'm trying to figure a few things out this year. I just want to say these are really dumb, basic questions because I don't know like anything about physics.

First of all, for the chinook design, a lot of people were talking about transmission systems for horizontal motors. Is using some kind of gear system very common? How do you even connect a rubber band to a gear like that..? And wouldn't that be quite heavy? Sorry, I feel really stupid because I've never really done anything with gears before and can't visualize how that would work. Does simply using thin tubes either curved or bent at a 90 degree angle also work?

Also, after struggling a lot last year with testing rubber bands, I figured I should probably actually like learn about torque...where can you get a torque meter and how do you use one with a rubber band? Again, sorry to anyone who's probably cringing at how dumb I am. I read posts, especially Jeff Anderson's, about how to use a torque meter to compare data and such but I don't even know how to use a torque meter period.....

For lubricating rubber bands, is armor-all considered the best lubricant? I remember something about using hand lotion, wouldn't that be bad for rubber bands?

Is the Freedom Flight kit really doing a chinook design this year? I'm kind of sad because our school's team just like didn't get funding this year because the money isn't for "classroom purposes" so we're frantically trying to raise money for builds, and I feel like it's not possible to be competitive in helicopters without the kit.

Sorry for such a long post.
Don't worry, everyone is a novice at some point. Based on your level of experience, I would stick to a conventional helicopter for now. You'll learn more about what works and doesn't work that way, without the added variables of weight and torque balancing. Of course, this won't be competitive at anything but regionals, but you could build another helicopter when you get past that stage. Don't worry about gearing or any Chinook related problems until you have solved your normal helicopter problems. On torque, I would ignore it for now. It's really useful for finding the right thickness of rubber to use, to optimize performance, but it won't help you go from not flying to flying. If your helicopter has blades remotely similar to the FFM kit, use about .085 to .1 inch thick rubber, and get a good idea of how many winds it can take by testing. More winds is always better than less winds, all other factors constant. You also mentioned not having the funds for the FFM kit. I would strongly suggest trying to get enough money to buy it, if at all possible over building your own. The FFM instructions and materials are excellent, and personally made the difference for me. But if you can't afford the kit, here's a couple of things I learned in my first year of Helicopters:
Weight is everything. Use thin, light balsa if possible. Hot glue is a big no-no, use loctite gel superglue. Mylar is the best covering for blades, bar none. Make sure your blade covering is tight. Effective thrust bearings are extremely important. The nose button kits FFM sells are excellent for this. And good rubber is critical. FAI model supply is the best place to get it. Do not use office rubber bands.
Best of luck!

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Re: Helicopters C

Post by jander14indoor » October 18th, 2017, 2:46 pm

Let me reinforce the others points.
If you aren't flying 1-2 minutes with a conventional design, don't even worry about the chinook bonus. Master basic construction techniques, winding and flying skills FIRST.
You MUST build to very near minimum weight and maximum size to get good flight times. A little off will fly, but the times drop FAST with excess weight or undersize rotors.
Minimum weight is CRITICAL.
Weight is important.
Yes, I'm repeating myself, it is that important.
Rubber, yep. FAI Tan Sport or Super Sport is the way to go.
Others have pointed to torque meters, once you've got one and tried to use it, you'll probably have more specific questions. Bring them back we're happy to answer. But is hard to be anything but generic with generic questions.

If you want a design that's proven and free, look for the River City Rocket, good design from a couple of years back and scale up or down as appropriate to this years rules. It'll fly well enough to win many regionals if you do your part.

Jeff Anderson
Livonia, MI

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Re: Helicopters C

Post by DrDaveV » October 18th, 2017, 5:06 pm

coachchuckaahs wrote:Ten086:


For simplicity, start with a simple x-style rotor with 0.020 carbon rods for LE and TE. Set up for 6-8" pitch for your first build. Make a foamboard or balsa fixture to set pitch and build the rotors. Play with chord, pitch. Weigh sheets of wood at local hobby shop, you will find tremendous variation in weight.

If you build two rotors (you have to), it is not much different to make a Chinook style. Use two vertical rubber motors. If mounted horizontal, then you have the transmission issue, and you still need two pieces of rubber for counter-rotating. Keep it as simple as possible. If you go Chinook, you will need some vanes for stability.

I would start simple with a traditional axial two-rotor system, and then adapt the same rotors to Chinook once proficient at flying the axial.

Chuck
AAHS
I am a new coach with a lot of experience in other areas but little knoweledge of helicopters or planes.

I get a lot of the abrieviations like trailing edge and leading edge but really don't understand how all these things fit together.

6-8" pitch ??
Chord, I know what it is mathematically but what does that mean in terms of rotors?
What do people use for blade material?
Do you all use the same material rubber for the motors?

Where do you get your materials?

I know there is a lot of information here on Scioly and youtube but are ther any boks or websites with basic plans, designs, sketches, ...

Thanks in advance,
David

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Re: Helicopters C

Post by Unome » October 18th, 2017, 6:45 pm

DrDaveV wrote:
coachchuckaahs wrote:Ten086:


For simplicity, start with a simple x-style rotor with 0.020 carbon rods for LE and TE. Set up for 6-8" pitch for your first build. Make a foamboard or balsa fixture to set pitch and build the rotors. Play with chord, pitch. Weigh sheets of wood at local hobby shop, you will find tremendous variation in weight.

If you build two rotors (you have to), it is not much different to make a Chinook style. Use two vertical rubber motors. If mounted horizontal, then you have the transmission issue, and you still need two pieces of rubber for counter-rotating. Keep it as simple as possible. If you go Chinook, you will need some vanes for stability.

I would start simple with a traditional axial two-rotor system, and then adapt the same rotors to Chinook once proficient at flying the axial.

Chuck
AAHS
I am a new coach with a lot of experience in other areas but little knoweledge of helicopters or planes.

I get a lot of the abrieviations like trailing edge and leading edge but really don't understand how all these things fit together.

6-8" pitch ??
Chord, I know what it is mathematically but what does that mean in terms of rotors?
What do people use for blade material?
Do you all use the same material rubber for the motors?

Where do you get your materials?

I know there is a lot of information here on Scioly and youtube but are ther any boks or websites with basic plans, designs, sketches, ...

Thanks in advance,
David
A picture (that's the NSO example image from last year) may be the easiest way to understand a helicopter in the context of Science Olympiad. The chords are the curved members crossing each of the blades - there are three per blade in this image.

Blade material - do you mean the rotor frame or the covering? (typically the former is a combination of carbon fiber and balsa wood, while the latter is Mylar or some other plastic film)

Pretty much anyone aiming to be any sort of competitive will be using FAI rubber (in some cases repackaged by others).

Sadly very little of the information from the forums on builds has been transferred to the wiki - that's one of the projects I'm hoping to work on after I graduate.

Others can comment on the rest, which I don't know very well.
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Re: Helicopters C

Post by andrew lorino » October 18th, 2017, 6:50 pm

DrDaveV wrote:
coachchuckaahs wrote:Ten086:


For simplicity, start with a simple x-style rotor with 0.020 carbon rods for LE and TE. Set up for 6-8" pitch for your first build. Make a foamboard or balsa fixture to set pitch and build the rotors. Play with chord, pitch. Weigh sheets of wood at local hobby shop, you will find tremendous variation in weight.

If you build two rotors (you have to), it is not much different to make a Chinook style. Use two vertical rubber motors. If mounted horizontal, then you have the transmission issue, and you still need two pieces of rubber for counter-rotating. Keep it as simple as possible. If you go Chinook, you will need some vanes for stability.

I would start simple with a traditional axial two-rotor system, and then adapt the same rotors to Chinook once proficient at flying the axial.

Chuck
AAHS
I am a new coach with a lot of experience in other areas but little knoweledge of helicopters or planes.

I get a lot of the abrieviations like trailing edge and leading edge but really don't understand how all these things fit together.

6-8" pitch ??
Chord, I know what it is mathematically but what does that mean in terms of rotors?
What do people use for blade material?
Do you all use the same material rubber for the motors?

Where do you get your materials?

I know there is a lot of information here on Scioly and youtube but are ther any boks or websites with basic plans, designs, sketches, ...

Thanks in advance,
David
Pitch- Imagine the rotor as a slice of a screw. The pitch is how far this hypothetical screw would travel in one turn. Say your rotor is 1" high, and a blade is 45* wide. The blade would travel 8 lengths of itself in one rotation. So, therefore, if it were a real screw, it would have travelled 8". So, to find the pitch, multiply the blade height by 360/degrees width.
Chord- How wide the blade is. For a wing it would be measured in inches, for a propeller degrees would be more practical.
Typically thin balsa covered in mylar (think thin, non-sticky saran wrap) is used, but carbon fiber is gaining prevalence.
Tan Super Sport rubber is the best rubber for flight events. FAI model supply sells it.
The best place to go for a kit is Freedom Flight Models. They provide all of the materials, fixtures, and instructions to build a viable helicopter. All you need is glue and a winder. And the kits are specifically designed to be competition legal. I have personally found his kits to be excellent quality, and they are always innovating year-to-year.
Good Luck!

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Re: Helicopters C

Post by retired1 » October 20th, 2017, 1:56 pm

Based on a picture of this years helicopter, I think that the glue portion of the assembly should be fairly simple. It uses several "strings" as bracing and that could be a bit of a problem.
It has a separate rubber for the two rotors, so I think that you will need a lot of practice in the winding and launch portion to be competitive.
I suspect that the chopper will be more fragile to handling than the conventional coaxial ones. In flight "hits" should be no more delicate.
That is personal opinion without having seen the actual kit.

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Re: Helicopters C

Post by Ten086 » October 21st, 2017, 6:07 pm

Thanks for the responses! My maximum time last year was around 1:30 using the kit. I had my two helicopters at very very close to minimum weight at the very beginning, which I think was at states, but after more testing and breaking and lots of regluing, they were just kind of a mess by nationals. I also don't have a good testing area because one of the gyms at school has way too much stuff on the ceiling and the smaller gym has literally has nails poking out of the ceiling (???) which definitely added to my struggle with rubber bands because I couldn't test a lot.

I'd really like to go for the Chinook this year--I might start with a regular helicopter as it seems like everyone is suggesting, but I feel like the Chinook bonus is just too good to not go for.

JasperKota, thanks so much for the info about torque meters! I didn't even know that Freedom Flight Models sells so many extra materials like torque meters/winders/scales/(and poles?)... I'm just now realizing that all the people at nationals I saw were using torque meters with a board. I'd literally been using a cutting board with a hook on the end when I winded my motors. I would stick my (heavy) backpack on top and then stretch the rubber band out really far and wind because I tested without my partner. (If anyone saw the panicking girl crying at nats, that was me because I realized I didn't bring my cutting board, couldn't find my partner, and ended up literally jamming an extra Wright Stuff propeller in a school box, sticking my leg out to hold it as far from me as I could, and winding like that.......)

coachchuckaahs, thanks for the advice! I made my own helicopters for our only invitational and regionals last year, and then switched to the kit because all the other schools had it and my own helicopters were definitely not competitive with the kit. Where do you get carbon rods other than from the kit? Also, for a Chinook, wouldn't using vertical motors mean they have to be pretty short? And what do you mean a vane for stability?

andrew lorino, thanks for the tips! I only had the two thicknesses from the kit last year because I wasn't sure what other sizes to get. I was also trying to test length of the rubber band at the same time because I was pressed for time, which I'll definitely try to change this year. I will probably end up having to buy the kit with my own money, but I agree that the instructions and materials are really really good. I learned so much from the first helicopter I built with the kit--before that, I wasn't even using a jig of any kind, which made everything extremely inconsistent and just pretty awful in general. Thanks so much again, best of luck to you too! :)

Mr. Anderson, thanks so much for tips as well as the countless other posts of yours that I've read through. My first helicopter got maximum 50 seconds, and then with the kit my highest time was around 1:30. I feel like my time using the kit helicopter doesn't really count though. I definitely know minimum weight is crucial, which worries me a bit because last year every repair just added more and more weight. Thank you very much, and I will probably have more specific questions later in the season when I feel like I know what I'm doing.

Has someone posted a picture of this year's kit somewhere? Could I get a link?
Just trying my best...

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Re: Helicopters C

Post by Unome » October 21st, 2017, 6:38 pm

Ten086 wrote:coachchuckaahs, thanks for the advice! I made my own helicopters for our only invitational and regionals last year, and then switched to the kit because all the other schools had it and my own helicopters were definitely not competitive with the kit. Where do you get carbon rods other than from the kit? Also, for a Chinook, wouldn't using vertical motors mean they have to be pretty short? And what do you mean a vane for stability?
From what I have observed (keep I mind I know little about this event): a vane refers to vertical plates extending outward perpendicular to the plane between the two axes, I assume to prevent the chinook from rotating (though I'm not certain).
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