Thread Tools
Aug 07, 2020, 04:55 AM
gpw
gpw
“There’s no place like Foam”
gpw's Avatar
Thread OP
You know EPS comes in many different weights , some VERY Light , meaning you can hot wire some Nice airfoils , making very light wings …
Latest blog entry: Lost plans
Sign up now
to remove ads between posts
Aug 08, 2020, 04:11 AM
Registered User
Quote:
Originally Posted by gpw
You know EPS comes in many different weights , some VERY Light , meaning you can hot wire some Nice airfoils , making very light wings …
You are right, the insulation foam from home depot seem to be low density. Still it should be cut smoothly with a cnc but by hand it is hit and miss.

Still after covering it with masking paper the result is pretty good and I may just use slices of adams board on the leading edge for a smooth finish.
Aug 08, 2020, 11:44 AM
Registered User
2 50 gr = 8.82 oz not 2 1/2 lbs. Many kids understand metric units. Lots of adults do not.
Aug 08, 2020, 12:17 PM
flyin' fool
goldguy's Avatar
Our government spent millions trying to convert us to the metric system back in the 70s. Yet, you can't buy a tap or die in metric without a special order. Although fasteners are readily available. The decimalised system is still dominant.

Most here find weights, measures, speeds and temperature fairly easy. Only because us who think in metric don't have to convert.

It's easy, makes more sense and besides, 95% of the world is metric.
Aug 08, 2020, 01:36 PM
An itch?. Scratch build.
eflightray's Avatar
If the FAA, AMA, and government is making your head spin ......

There's always the Control Line forum, no restrictions

.
Aug 08, 2020, 01:53 PM
Got shenpa?
flieslikeabeagle's Avatar
Quote:
Originally Posted by Tcat
2 50 gr = 8.82 oz not 2 1/2 lbs.
Yes, we all know that on this thread. Most people won't; and they might go for the simplistic (and quite wrong) statement that 250 grams = 2.5 lbs, simply because of the vague similarity between "250" and "2.5".

It was just a joke in either case.
Quote:
Originally Posted by Tcat
Many kids understand metric units. Lots of adults do not.
My experience says otherwise. I've had the good fortune to help maybe 3,500 young adults move towards their educational goals, the majority of those in the USA. My experience was that only a small percentage of them had any idea at all of metric units; and towards the end of my time in the USA (circa 2014 or so), most of them did not know imperial units either.

Case in point: I created and used to give my students a simple math lab on the subject of precision and accuracy (they are two different things, with very specific definitions to a mathematician, engineer, or scientist). The first step was to measure the length and diameter of a number of small aluminium rods, first with a ruler, then with vernier calipers, then with a micrometer. Then we would do various calculations of volume, surface area, and so on, in order to study how using increasingly precise measurement tools altered the accuracy and precision of the results.

After a number of years of using this lab as part of one of the courses I taught, I had to stop doing it, because it got to the point where about 75% of my students were unable to measure the diameter of the rods using a ruler. One of the rods was 1/2" diameter (about the size of a finger), and about 75% of my students would report that it was four inches in diameter. If I gave them rulers marked in tenths of an inch (instead of eighths), they would now report that it was five inches in diameter.

What was happening was that they would simply count how many of the smallest divisions on the ruler matched up with the rod's diameter (i.e. 4 markings each of one-eighth of an inch in the first case, or five markings each of one-tenth of an inch in the second case). It was bad enough that they couldn't tell the difference between eighths of an inch and tenths of an inch; but the real shocker was that these young people - born and raised all their lives in the USA - didn't have the faintest idea that four inches is about the width of your palm, and not the width of your finger.

By 2014, I was seeing a large percentage of students who said they had never used a screwdriver in their entire lives; never used a hammer; couldn't cut a roughly straight line through a sheet of paper with a pair of scissors; and had no idea of many concepts very familiar to previous generations, such as "in inch is about this big".

Our kids grow up in a very different world than we did. If you spend all your time in a virtual online world, poking at your phone, you stop having (or never develop) a functional understanding of the real physical world around you. If you never use a ruler while you're growing up, maybe to lay off distances on a map to see where you're going camping, or to draw up an idea on paper, or even to cut a piece of wood to size, you also never develop an understanding of how big an inch is. (Same goes for metric units in metric countries, of course.)

Being in Los Angeles, I rarely had a student who had grown up on a farm. But whenever I did, that young person always had a much better handle on things like basic units and basic tool use, than the kids who grew up without using their hands.

-Flieslikeabeagle
Aug 08, 2020, 01:58 PM
Got shenpa?
flieslikeabeagle's Avatar
Quote:
Originally Posted by goldguy
It's easy, makes more sense and besides, 95% of the world is metric.
I agree entirely, but when I moved to Canada, I found it to be extremely mixed-up about units. I buy gasoline for my car in litres, and the road signs are marked in kilometers - but the air supply for my tires (tyres) has a pressure gauge that reads in pounds per square inch, and tyres themselves are sold in inch-sized diameters. Go into Home Depot and at least 90% of what you see has imperial dimensions.

Same story with RC planes too - prop diameters and pitches seem to be specified in inches even in metric countries.

It's an imperfect world out there!

-Flieslikeabeagle
Aug 08, 2020, 02:42 PM
Got shenpa?
flieslikeabeagle's Avatar
Quote:
Originally Posted by eflightray
There's always the Control Line forum, no restrictions
Now you've gone and done it. Watch for upcoming FAA restrictions on maximum control line length, maximum model speed, max permitted loudness, and the maximum number of times a control-line pilot is allowed to twirl per day before requiring an expensive additional permit.

-Flieslikeabeagle
Aug 08, 2020, 07:06 PM
treefinder
springer's Avatar
Beagle, your story about kids and measurements is incredible, and incredibly bad! Hard to believe in this day and age that kids are so unprepared for the real world. Also just one more anecdotal evidence of the unsupportability of cramming a bunch of folk into big cities!
Aug 08, 2020, 10:10 PM
Got shenpa?
flieslikeabeagle's Avatar
Quote:
Originally Posted by springer
...incredibly bad...
Yeah, it was pretty hard for me to get used to the reality that was being demonstrated to me. I guess our parents were right when they told us to "use it or lose it"!
Quote:
Originally Posted by springer
Hard to believe in this day and age that kids are so unprepared for the real world.
The artificial world most people live in now has different rules. You don't need to know how to make change, because you use your debit or credit card, and the cash-register sucks the right amount of money out of your bank account. You don't need to know how big an inch is, because you never make anything with your hands. You don't need to know how to use a hammer, because you live in an apartment where it's forbidden to hammer nails into the walls anyway. You don't need a mental map of your city, because your GPS tells you every turn to make.

But when things go wrong with the artificial electronic world, people become very helpless. I walked into a local 7-Eleven store one day to find two employees and a customer, all puzzling over how much change to give him. The problem was that the cash register was down. I don't recall exact numbers but it was a bit like this: the customer had handed over two Toonies (Canadian two-dollar coins) to buy something - lets pretend it was a sandwich - that cost, shall we say, $3.25. And nobody could figure out how much change to give the customer.

I tried walking them through it...subtract 3.25 from 4 to get 75 cents. Nope, that didn't compute. How about subtract 3 dollars from 4 dollars, that leaves you one dollar. Now subtract the extra 25 cents from a dollar, that leaves you 75 cents, so you owe the customer 75 cents.

Nope, still no glimmer of understanding. So I tried a third approach...let's add coins to 3:25 until we arrive at $4, and since the customer paid you $4, the amount of coins we added will be the right change to give him...nope, that didn't compute either.

Finally I just said "Trust me, you owe him 75 cents." I don't know if they believed me or were just too confused to bother any longer, but they gave the man 75 cents, and he left.
Quote:
Originally Posted by springer
Also just one more anecdotal evidence of the unsupportability of cramming a bunch of folk into big cities!
Agree 100%. Recently I watched a documentary film about some of the many problems that plague "Megacities" - cities with populations over 10 million, in some cases, over 20 million, even over 30 million (Tokyo has 37 million). There are a lot of these megacities now.

-Flieslikeabeagle
Aug 09, 2020, 06:41 AM
Registered User
RCvertt's Avatar
Has the requirement for a transponder gone into effect yet?

I also recall there is a 50 percent build rule. If you scratch build less than 50 percent of your plane then it won't be deemed airworthy by the FAA without them inspecting your build facilities first.

So if you don't carve your own props, make your own receiver electronic circuit boards, wind your own motors and just use off the shelf items items then your scratchbuilt isn't FAA compliant until they FAA determines your garage is FAA compliant, which I guarantee it won't be.

The only thing I'm not to clear on is if this build requirement applies to rc aircraft flown in an FAA designated area? I'm assuming it does since you still need a transponder in an FAA designated area. You just don't need a (part 107) license.
Aug 09, 2020, 08:03 AM
treefinder
springer's Avatar
Rcvertt, where did you see that about the 50% rule?
Aug 09, 2020, 10:49 AM
Got shenpa?
flieslikeabeagle's Avatar
Quote:
Originally Posted by RCvertt
I also recall there is a 50 percent build rule. If you scratch build less than 50 percent of your plane then it won't be deemed airworthy by the FAA without them inspecting your build facilities first.
Wait, what? If you scratch build 100% of your plane the FAA considers it airworthy, but if you scratch build less than 50% of it, they have to inspect your build facility?

That doesn't compute (the more of the model you build in an un-inspected facility, the more airworthy it is?) Is that perhaps backwards? If you scratch-build more than 50% of it then the FAA has to inspect your facility?

In any event, this is one more utterly ridiculous item in a long string of ridiculous items. From a look at Wikipedia, it looks as though the requirements for a 253-lb ultralight aircraft in the USA are much less stringent than the requirements on a 251-gram "drone": https://en.wikipedia.org/wiki/Ultral...(United_States)

Note in particular "Ultralight vehicles and their component parts and equipment are not required to meet the airworthiness certification standards specified for aircraft or to have certificates of airworthiness". There's no need for an FAA inspection - you can build your own ultralight and fly it, without pilot training, without an FAA inspection, without an airworthiness certificate.

Ultralights also don't have to be registered, and don't have to carry a transponder.

If the "build requirement" is really part of the law, then it's becoming increasingly evident that the law was made by imbeciles or insane people.

Interestingly, at least on the Wikipedia page, there is no stated requirement that an ultralight aircraft should have a pilot on board. Nor is there a stated minimum weight for one. Perhaps your 500-gram foam parkflyer will qualify as a legal ultralight aircraft, though it will not qualify as a legal "drone"?

-Flieslikeabeagle
Aug 09, 2020, 01:04 PM
Out Standing In The Field
RexGalore's Avatar
Gee, Mr Beagle - thanks for informing me that my garage contains a whole bunch of foam "ultralight vehicles".


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion New faa rules part 107 non commercial fpv license required... Ionfreefly FPV Talk 53 Feb 07, 2018 05:17 PM
News FAA Special Rule for Model Aircraft Extension Jason Cole Model Aircraft & Drone Advocacy 306 Sep 04, 2016 07:13 PM
Discussion FAA Press Release – FAA Finalize Rules for Small Unmanned Aircraft Systems bluesgeek Multirotor Drone Talk 43 Jun 22, 2016 03:07 PM
Alert More on FAA rules rdemattei South Bay Soaring Society 14 Dec 28, 2015 03:57 PM
News FAA Special Rule for RC - More Responses Needed! Jim T. Graham Electric Plane Talk 58 Jul 24, 2014 12:33 PM