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Old Jan 14, 2009, 09:34 PM
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Help!
50% Piper Cub build, need advice!

Hi all, im brand spankin new to these forums, first thread here, or anywhere at that. I have some questions I would realy like to find the answers to. I want to bild a 50% piper cub, yes 50% . I am looking into this as a future project this year. I want your opinions on how I should go about doing this. How would I get a lot of the parts for the plane, things like the engine cowl and windows. Im pretty sure they do not sell %50 parts for the cub. What I want to do is take a 1/4 scale set of plans, and scale them up 200% to a 1/2 scale cub at a printing place. Does this sound like the best idea to you? What plans would you reccomend to scale off of, and where could I find them, even better yet, are there any 50% plans for the piper cub? Any tips and possible obsticals that I might face on a big scale plane like this that you might catch, list em all! I am going to be making a blog on this project, and am going to be interested in the help you people can offer me as I go through the project. I plan on building this through the next 6 months, quite possibly longer.

This might seem like a project that is a bit above my skill level, but I plan on building a few smaller scale planes to fine tune my techniques and get some experiance.
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Old Jan 15, 2009, 12:11 AM
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Traverse City, Michigan
Joined Dec 2005
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You stated that you'd understand, so here goes:

My feeling is that if you have to ask these questions, you are not ready to take on this project. Anyone with enough experience to tackle this will know most of the answers.

I do not want you to become discouraged. I suggest building a 1/3 scale Balsa USA Cub. This will give you an idea of what you are up against. If you can successfully build and fly that model, then you MAY be ready.
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Old Jan 15, 2009, 12:17 AM
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Christchurch, New Zealand
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Go get a smaller kit and build that first then you can take measurements from it to scale up as well.
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Old Jan 15, 2009, 12:31 AM
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Quote:
Originally Posted by tomahawkflier
Go get a smaller kit and build that first then you can take measurements from it to scale up as well.
Might not be a bad idea. Do you think it would include full sized plans along with the kit? Im looking at a sig 1/4.
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Old Jan 15, 2009, 12:32 AM
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So ya, I might just get a kit to start with, a 1/3 or a 1/4. But I still want to hear what people might suggest on this future build.
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Old Jan 15, 2009, 01:35 AM
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Here's one to consider before that 1/2 scale.

https://secure.rcstore.com/pcd/eServ...N1YlRlcm09MA==
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Old Jan 15, 2009, 06:19 AM
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Traverse City, Michigan
Joined Dec 2005
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Quote:
Originally Posted by DT56
Here's one to consider before that 1/2 scale.

https://secure.rcstore.com/pcd/eServ...N1YlRlcm09MA==

The Nelitz 33% would be a good place to start. The plans would be more suitable to blow up to 50%, too.

Scolen3: Your speech patterns sound like you live in the States. Are you aware that in the US, you need a special AMA permit to fly a model that weighs more than 50# ? The model's construction also has to be inspected at certain points, and that all this is at your expense ?
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Old Jan 15, 2009, 10:47 AM
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Tucson, AZ, USA
Joined Nov 2000
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Bill Hemple sells a 1/2 scale cub. He flies it in unlimited free style at various acrobatic meets. You can find pictures of it in the AMA Expo forum. Look for vendor pictures. You can contact Bill at http://hobbybarn.com
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Old Jan 15, 2009, 11:13 AM
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Tom, you don't NEED an AMA permit to fly it. That is only needed if you're flying at an AMA field or you're an AMA member and would like your AMA insurance to cover any incidents relating to the model.

If you're not an AMA member or you don't care about the AMA insurance, no permits are required by anyone.

g.
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Old Jan 15, 2009, 12:46 PM
Zor
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Quote:
Originally Posted by geneb
Tom, you don't NEED an AMA permit to fly it. That is only needed if you're flying at an AMA field or you're an AMA member and would like your AMA insurance to cover any incidents relating to the model.

If you're not an AMA member or you don't care about the AMA insurance, no permits are required by anyone.

g.
Anyone can dive a car without a driver's license.
Anyone can fly a full size airplane without a pilot license if they know how.

They are just "breaking the laws" and take any responsibility in their own hands .

Zor
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Old Jan 15, 2009, 01:04 PM
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Quote:
Originally Posted by TomCrump
The Nelitz 33% would be a good place to start. The plans would be more suitable to blow up to 50%, too.

Scolen3: Your speech patterns sound like you live in the States. Are you aware that in the US, you need a special AMA permit to fly a model that weighs more than 50# ? The model's construction also has to be inspected at certain points, and that all this is at your expense ?
Ya, dotn worry about that, have that covered. As far as AMA, I have that, and I know some people with giant scale planes, so they could point me to the right direction.
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Old Jan 15, 2009, 01:14 PM
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Quote:
Originally Posted by TomCrump
The Nelitz 33% would be a good place to start. The plans would be more suitable to blow up to 50%, too.

Scolen3: Your speech patterns sound like you live in the States. Are you aware that in the US, you need a special AMA permit to fly a model that weighs more than 50# ? The model's construction also has to be inspected at certain points, and that all this is at your expense ?
That looks like a great set of plans. Is that a 1/3 scale plane? Im doing research, but how scale is it compared to the real plane, I might go with it. Also for AMA, a plane this big, does it have to undergo more inspection and certifacations than a big 3d plane that I commonly see at the airfield?

I really appreciate the help I am getting here.
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Old Jan 15, 2009, 07:26 PM
trying to kick the habit
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Joined Mar 2006
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Quote:
Originally Posted by Zor
Anyone can dive a car without a driver's license.
Anyone can fly a full size airplane without a pilot license if they know how.

They are just "breaking the laws" and take any responsibility in their own hands .
Totally different.

You need a DL to drive a car legally. You also need an additional endorsement to drive a big rig.

You need a license to legally fly a full size plane.

Since you dont need AMA to legally fly an RC plane, you dont need the certificate for the bigger one. There may be laws in the US prohibiting the flight of such a large aircraft but that has nothing to do with the AMA.
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Old Jan 15, 2009, 10:00 PM
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Joined Mar 2008
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This project covers many subjects. Tom Crump wisely brings up AMA membership as what I believe (for what it’s worth) is one of the leading limitations to taking on such a project.

The insurance benefits of AMA membership can be worth it’s weight in gold. And, like any insurer, the AMA is free to describe what rules and limitations will be followed in order to be covered by them. If a model is 55 pounds or more, the AMA requires an inspection of that aircraft. If the aircraft is within their coverage guidelines, they will cover it. But, they have the right to inspect it and to approve or deny coverage of it.

True enough, in the model aircraft arena, anyone can create and fly (operate) whatever they want. However, nothing is foolproof. You will be responsible for whatever damage is done in the case of a mishap. This can go well beyond how much time and effort that you put into your model, it can (and has for others) come down to how much of your current household and future earnings you want to put into your model. Why would you NOT invest in a safety net? For modelers, that safety net is either home owner’s insurance (good luck!) or AMA coverage, within AMA sanctions.

I am not attempting to discourage you from undertaking your project. I am only encouraging you to consider widening your field of vision to include personal responsibility in the (eventual) case of a mishap.

Consider the case of the 50% Spitfire (http://www.rcgroups.com/forums/showthread.php?t=970865) built by an experienced machinist, that ended up in a corn field. This model obviously weighed far more the 55 pound AMA limit. Imagine this model getting away from the pilot and ending up in a house, school, office building, bus stop. In other words, causing bodily harm or property damage. Would you able to cover the damage?

On another area of this project, I have wondered about building from enlarged plans. Are all materials enlarged by the same proportion as original plans? In other words, if a longeron is 1/4” in quarter scale, do we double it 1/2” in half scale? A former 3/16, do we double the thickness to 3/8”?

I am curious; why 1/2 scale?

Thank for sharing this project with us,

EJWash
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Old Jan 15, 2009, 10:08 PM
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United States, WA, Hoodsport
Joined Mar 2008
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Quote:
Originally Posted by Crashaholic
Totally different.

You need a DL to drive a car legally. You also need an additional endorsement to drive a big rig.

You need a license to legally fly a full size plane.

Since you dont need AMA to legally fly an RC plane, you dont need the certificate for the bigger one. There may be laws in the US prohibiting the flight of such a large aircraft but that has nothing to do with the AMA.
Crash,

You are arguing the difference between legally operating a car/full-size aircraft and liability. Yes, you can drive/fly without a license, but that is in the face of the law. If you get pulled over in a car without being able to provide a license, or unable to show a pilot license, you get dinged for not proving you have the privilege to operate such vehicle. If you cause damage, be you licensed or not, you may be responsible for that damage. Why take the chance?

EJWash
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