Here's A Simple & FREE First Foam Build Plan! (Part 2)  
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Here's A Simple & FREE First Foam Build Plan! (Part 2) - 1/15/2008 2:56:40 PM   
critterhunter



Posts: 2529
Joined: 9/24/2004
From: Brook Park, OH, USA
Status: offline 		Here's the new thread.

The original thread can be found here.

http://www.rcuniverse.com/forum/m_3511182/tm.htm

However, much of what was covered there will go gone over in this thread and condensed as most of us were learning how to work with foam and scratch build for the first time. This was (and is) an excellent plane to cut your teeth on and get into foam scratch building. I'll be shortly posting info on how to make hot wire cutting tools, where and what types of foam you can get, electronics, and so on. More importantly, the process of building this great yet simple plane will be covered. Other builds are also welcome, be they anything made from any type of foam. Let the fun begin...

Here's the plans for the plane...

http://www.qnet.com/~skif/plane.html

Here's the link to FoamFlyer's excellent website where I first ran across the plans for this plane. It's looks quickly sucked me in and it seemed like a simple (& free ) foam build to get my feet wet. While you're on his website check out his project history pages. There are many similar builds to the "So" we are building with his plans, along with some other excellent ones. They should give you some ideas for future builds, and you can use the knowledge from building the original "So" to build them and others. Making this plane was such a great learning tool for me.

http://www.qnet.com/~skif/rcmain.html

He also has some great articles, including ones on how to build cheaply, which I love. I tend to buy the cheapest lipos, motors, speed controls and so on that I can find. With a little research you can find the good stuff and avoid the junk thats out there. No longer does flying RC have to be expensive, and when you build with foam it gets dirt cheap. Not to mention the extra satisfaction you get from knowing you are flying some thing you built with your own two hands and didn't buy off the store shelf.

The original plane design uses a brushed motor and nimh packs. If you stick with the original plans, mounting the motor and such as suggested, when using a brushless motor and lipo the plane will probably be tail heavy. It took me three builds to tweak a few things on the plan dimensions. This wasn't all due to the tail heavy conditon (mostly pilot error), but it did need some tweaking for me. I'll be posting this information with photos as I build #4, which I just cut the wing out for last night.

Mainly, you need to move the fuse forward to flush with the trailing edge of the wing, lengthen it's nose a bit, and move the booms to the leading edge. Keep your servos in the very heads of the booms and your electronics as far forward as possible and you should be good. More details as I post the progress.



< Message edited by critterhunter -- 1/15/2008 3:27:31 PM >

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       Post #: 1

RE: Here's A Simple & FREE First Foam Build Plan! (Part 2) - 1/15/2008 3:38:15 PM   
critterhunter



Posts: 2529
Joined: 9/24/2004
From: Brook Park, OH, USA
Status: offline 		First thing to post would I guess be the Clark-Y airfoil. You can find it on the web but here's a repost from Fisher in the original thread. When I grab an airfoil now I load it into paint and just change the attributes (sp?) of the horizontal/vertical. Just increase or decrease them both by the same percentage number with paint and then print it out. Measure the length of the airfoil and if it isn't what you want play with the numbers again. Probably other ways to do this but this one works for me.

Repost From Fisher...

I worked on an airfoil template for over an hour that would print as a JPG and when I posted it the site cut it down too small to use you could print it and enlarge it on a copier until it is 7" long on the horizontal base line. Remember to use the flat horizontal base line for the bottom of the wing. Not the one aligned with the numbers.

I will try to PM it to you. Maybe that will work.

I just clicked on the embeded image. maximized it on screen. Copied it and pasted it into a Word Document. Set the page to landscape and drug the lower right hand corner down further to the right until the template was 7" long. Print and your ready to go.




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_____________________________

If you believe in Global Warming then shut your mouth. All that hot air is warming up the planet, remember?

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       Post #: 2

RE: Here's A Simple & FREE First Foam Build Plan! (Part 2) - 1/15/2008 3:50:17 PM   
critterhunter



Posts: 2529
Joined: 9/24/2004
From: Brook Park, OH, USA
Status: offline 		Another repost from Fisher with good info on the airfoil...

The leading edge is rounded to the bottom, so I had to extend the template beyond the edge of the base board to allow the hot wire to follow around template without getting caught. The intended bottom line of the airfoil template should be the solid horizontal line that begins under the leading edge curve and extends under the numbers. If you need me to I can have another go at making the template less ambiguous. Your observation regarding the wing thickness was right on. It should be about an inch think at the deepest point.

(end quote)

I ended up using the wrong baseline for my airfoil but it still works good. I'm missing the curve under the leading edge, but I just use my oribital sander to sand that into the wing. Quick and easy. Remember that the airfoil should be 7" wide. Measure what you print out. More info on building the jig and hot wire tools later.


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If you believe in Global Warming then shut your mouth. All that hot air is warming up the planet, remember?

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       Post #: 3

RE: Here's A Simple & FREE First Foam Build Plan! (Par... - 1/15/2008 7:50:29 PM   
ken 68


 

Posts: 791
Joined: 5/5/2006
From: Central Bridge, NY, USA
Status: offline 		Hook me up i'll watch. Im in the process of checking out some new receivers. I have 2 new Corona RP4S1's that need to be checked out. They had some problems with the first ones not wanting to lock on to yout transmitter. They don't use crystals. I also bought a couple of $4.50 6 channel receivers but I need the big crystals for them. Wheres the best price for single big xtals ? I bought some from BP products but there all small ones.

OH While your on wings look up the Clark-Y modified and show what it looks like. I can't get it to come up on this slow dial up. Happy building.

Ken

(in reply to critterhunter)
       Post #: 4

RE: Here's A Simple & FREE First Foam Build Plan! (Par... - 1/16/2008 3:26:48 AM   
calvino


 

Posts: 6286
Joined: 4/17/2007
From: Thousand Oaks, CA, USA
Status: offline 		neat, glad to see the thread in pt. 2, PS, THANKS FOR THE CLARK AIRFOIL, check your PM's (crit)

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(in reply to ken 68)
       Post #: 5

RE: Here's A Simple & FREE First Foam Build Plan! (Par... - 1/16/2008 3:44:03 PM   
critterhunter



Posts: 2529
Joined: 9/24/2004
From: Brook Park, OH, USA
Status: offline 		Nice to see you guys are game for the new thread. I'm hoping Fisher and Saucerguy will pop in and contribute, as well as the others from the past who did. With a little luck this thread should be more condensed and to the point, since most of us were learning scratch building, let alone this plane. I'll make an effort to try to be as short and to the point as possible, but no promises.

For any lurkers checking into this plane, I should mention that both beginners and experienced pilots should find it worth building. Even with a single aileron it'll challenge you. I've said this in the past, this plane flies like no other I've ever flown. It almost feels like it will stop and turn around in mid air if you have the center of gravity right and not too much weight. A little "up" on the elevator and then a quick left or right and it will nose around real quick. It also has real good low and high speed ability. It for sure will handle at lower speeds better than my Stryker, and the Stryker does a really good job at that so it's saying a lot. This "So" planes traits and characteristics are just a real joy to fly. Add the killer looks and cheap and easy building and you've got a real winner.

Calvino, couldn't understand what you were asking for in the PM? I made a mistake in the above info on adjusting the size of an airfoil. What I do is load it into paint and then use the "Stretch/Skew" function to increase or decrease the picture size. Then print it out and measure the length of the airfoil. If it isn't what you want (7" on the So plane), then go ahead and change the stretch/skew numbers again to adjust it and try again. I tend to keep both the vertical and horizontal numbers the same. IE: If you want it smaller, try 80% for both. However, you can adjust the vertical to get the airfoil less/more thick. This isn't real critical in my experience. My airfoil happens to be less thick than what Fisher suggested, as I went with the higher horizontal line. Still, it's plenty thick enough. Remember too that thicker airfoils tend to have higher lift than thinner ones, while thinner airfoils tend to have less drag and more speed. The Clark-Y is a very high lift airfoil, one of the best.

Ken, I'll throw that airfoil up to soon enough. I have a bunch of pictures and such to post first.

Somebody PM Fisher and tell him to get over here!


_____________________________

If you believe in Global Warming then shut your mouth. All that hot air is warming up the planet, remember?

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       Post #: 6

RE: Here's A Simple & FREE First Foam Build Plan! (Par... - 1/16/2008 6:02:49 PM   
critterhunter



Posts: 2529
Joined: 9/24/2004
From: Brook Park, OH, USA
Status: offline 		Another addition to adjusting airfoils in paint. I'll use the cut function to grab the airfoil alone off the page and then place it in the far upper left corner of the screen. Then use attributes to delete the rest of the screen fairly close to the airfoil. Now when you print it out the printer won't cut it in half or create two pages. Just guess with the numbers on attributes until you get a box fairly close to the airfoil. Then use stretch/skew as covered in the messages above. The screen size will automaticly adjust as you increase the size of the airfoil.

First step on this plane for newbies would be to build a hot wire bow. It's simple and easy and you probably already have most of the parts laying around in the garage. I used some garden tool wood handles for mine. Set the bow up so that it looks like an "I", with one end of the "I" being connected to the main beam via a bolt, nut, and washers so it can pivot up and down. Then attach a spring (look in the screen door section of hardware stores) to both ends of the bow. This will keep constant tension on your cutting wire by pivoting one end of the bow. The other end of the bow should be stationary by bolted or screwing to the main beam. It's easiest to attach the wire first and then your spring.

There are various types of wire and gauges to use on a cutting tool. What you need will depend on the length of the wire and the volts and amps being put out by your charger. I'm using .022 stainless steel fishing leader from a local tackle store. With my 40" bow and my car battery charger set on 12V 55 amp cold starting mode it gets the wire just right without the need for a dimmer. The charger self regulates so it isn't putting out the full 55 amps. This wire is cheap, like $3 for 25 feet. Pick up a few diameters if you are unsure what you might need with your charger and not using a dimmer.

I hitch the charger leads to the eye bolts at each end of the bow where the fishing leader is tied to. If you notice the wire is not getting hot enough then slide one of the charger leads onto the wire a few inches. The shorter the distance between the charger leads the hotter the wire will get. Remember too that hitching the charger leads up to the eye bolts may stop the wire from heating up at all.

How hot does the wire need to get? If it gets too hot and glows red for more than a few seconds it will snap, so always wear eye protection. Normaly the best cutting temperture is just below it glowing red, but it depends on type of foam, how thick, and how fast you like to cut. If the wire is dragging and skipping through the foam the heat is too low. If the cut is too wide the wire is too hot and melting foam around it that it isn't even touching. Variables are type of foam and how fast or slow you like to move the wire.

Below you'll find a picture of the cheapest charger I found with the features I wanted from Harbor Tool & Freight. Price is under $30. With the numerous amp settings as well as 6 or 12 volt you can almost find the right heat range for most tools you may build in the future. The starting mode versus the charging mode can also help in that respect. Charging mode often will turn on/off as it gets tricked by your tool and thinks a battery is charged. This normaly happens quickly over and over in a matter of seconds, so it can aid in regulating wire heat.

I mostly find myself using the starting mode at 55 amps, though, and then use a dimmer switch to control the heat that way. With this method you can be sure that you'll be able to find the right heat range for any tool. Just remember, if using a dimmer or various charger settings on a new tool, ALWAYS start with the lowest voltage and amps. Test the wire on some foam and slowly work your way up. If you start out too high then the wire will instantly glow red and snap. Once you know what works the red glow isn't a problem with a dimmer. I often bring the wire just up to glowing red and then back it off a bit for a good cutting heat. It's also a great way to clean the wire by burning off debri.

In determining the size of your bow, remember that if the wire gets too long it won't get hot enough with certain power sources. I find a 40" bow is about perfect. You need a few inches of clearance on both sides of the bow for the charger clips and to clear the wing jigs on a 3 foot wingspan when cutting. If you want to make longer wings that won't be a problem, just cut two out and glue them together. More on that later on.

You'll also see in one of the photos below me just finishing a gravity cut. A gravity cut is a quick and easy way to cut a straight line with a bow. It's great for lopping off a square chunk of foam that you plan to to further cut into a wing or such. Just weight one end of the foam on a table, then hang the bow on the foam where you want to do a straight cut. Make sure the bow is fairly balanced on the foam by sliding it one way or the other to correct. Then just plug it in and let the bow do the work. Be ready to catch the bow when it cuts through the foam but don't touch or bump it until it's done cutting. You can see the piece I just cut leaning against the side of the work table, and the piece it was cut from weight down on the bench.

More later on dimmers as well as another handy tool (not required but very useful) called a table hot wire cutter.



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_____________________________

If you believe in Global Warming then shut your mouth. All that hot air is warming up the planet, remember?

(in reply to critterhunter)
       Post #: 7

RE: Here's A Simple & FREE First Foam Build Plan! (Part 2) - 1/16/2008 6:31:39 PM   
critterhunter



Posts: 2529
Joined: 9/24/2004
From: Brook Park, OH, USA
Status: offline 		Here's some photos of the hot wire table cutter and some photos. Sorry about the quality of these pictures as I was using a web cam at the time. I'll try to dig up some better ones. But first, a re-post from the old thread from me...

Yesterday I took about an hour to build my bandsaw hot wire cutter . Stole a good bit of the design from other hot wire cutter links and modified them a bit to my liking and building skills. Posted are three photos of the unit minus the cutting wire. I hitched up a .022 diameter wire last night for a test run and forgot I still had the battery charger set at 12V 6 amps. This was obviously too much power as the cutting wire instantly turned red hot and then snapped. This charger has a .2 to 1.2 amp variable dial as well so I think I'll try that next, creeping it up until I see the wire start to glow and then back it down. If this is still too much power at 12V I'll flip the charger over to 6V and try that. All of this would be mute if I'd just wire up that dimmer switch to the AC side of the charger. Then I could leave it at 12V 6 amps and then just slowly crank up the dimmer until I see things glow and back it off.

Three photos that follow are of the board (22x21 inches and a close up of the spring mounting area. I used a brass bolt, nuts and washers at the top as I intended to mount one of the charger wires here. However, I decided it might not be a good thing to pass a current through the spring (?) and get it hot as well, so I'll just attach the charger lead directly to the cutting wire where it hitches up to the spring. On the other photo you can see the bottom of the bandsaw table and how I have that rigged. Again, I'm using a brass bolt, nuts, and washers here to both hold the cutting wire and to hold the other lead from the battery charger. The cool thing about this entire setup is I have this bolt and the one on the top end at 90 degree angles from each other. This means I can adjust two nuts on either bolt to position the cutting wire exactly where I want it to get a perfect straight up and down cutting wire in relation to the board surface. In the one picture you'll notice I have bent the white shelf bracket's tip upward so the bolt going through it's hole would be in a horizontal orientation. No test cuts yet but maybe tonight after work.

(End Quote)

Since that post and the below photos I've done a few things to the table cutter. I've shortened the spring so the .022 wire is longer and can do cuts on thicker foam. I've also hitched up a $5 dimmer switch to the charger to adjust the heat range. The charger being used with this table cutter is an old one that can support 12V at 6 amps. You simply plug the charger into the light dimmer switch and then the light dimmer into the wall. As you adjust the dimmer it will adjust the power from the wall going into the charger. This causes the charger to raise or lower the amount of power going to the cutting wire so you can get the right heat range. If I need to use the dimmer with my newer charger shown pictured above that I use with my bow and various other tools, I simply plug that charger into the dimmer. I could use the new charger to power this tool, but since I had the old one laying around I figured it could stay put for use with the table cutter most of the time.

Table cutters like this are great tools for doing smaller cuts or cuts that aren't straight, such as the nose of a fuse. They eliminate the need for wood body jigs that would normaly be used in order to guide the big bow for accuracy. Simply trace the outline of the cut you want onto the foam and then use your table cutter to cut it. It also works great with flat foam for things like tail feathers. If you trace the outline onto flat foam with a pen with enough pressure to crease the foam a bit, the hot wire will follow the cut and guide your hand. Just remember to use less heat with thinner foam than you would with a fuse and such.

The parts needed for the table cutter are quick and easy to get. I garbage picked the table and bought the shelf bracket, spring, and brass bolts/nuts/washers from a hardware store. I've also since made the components more portable. The charger now just clips it's leads onto two bolts on one of the legs of the cutting table. Two wires run from these bolts to the cutting wire. This way I can unclip the charger for other uses without removing the leads at the cutting wire ends. I've also thrown legs on the table and hung the dimmer from one of them. I'll try to dig those pictures up.

One final note. To get the cutting wire straight simply adjust the nuts on the two bolts and use something like a right angle ruler to check that the wire is straight up and down from two sides in relation to the table surface. While you can get by with just a bow, I'd say the table cutter is just as useful for building planes.




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< Message edited by critterhunter -- 1/16/2008 7:54:28 PM >

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If you believe in Global Warming then shut your mouth. All that hot air is warming up the planet, remember?

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       Post #: 8

RE: Here's A Simple & FREE First Foam Build Plan! (Part 2) - 1/16/2008 6:43:58 PM   
critterhunter



Posts: 2529
Joined: 9/24/2004
From: Brook Park, OH, USA
Status: offline 		Here's some better pictures of the table cutter along with the new mods I did to it, but the shorter spring/longer cutting wire was done after the photos. You can also see a picture of a mini bow I made for doing small free hand cuts that would be difficult with the big bow, yet are in areas of a piece of foam that would be in the way of the table cutter. For instance, I like to use this mini bow to cut ailerons out of a wing. I simply put a right angle metal ruler onto the wing with weights so it doesn't move in the exact spot I want the aileron, then just slide the wire across the ruler for a perfectly straight cut.

Here's a re-post on the mini bow...

I used one of the fiberglass rods from a garbage picked patio umbrella I have laying around to function as both my load spring and bow. .022 gauge stainless steel fishing leader. Fiberglass tube already had eyelits on it's ends to tie my wire to. Attached power leads a bit after the eyelits to hopefuly avoid the tied wire ends from getting hot and melting the wire free from the bow.

Isolated the bow at the other end of the garage (I only have one good eye as it is) and played with the settings on one of my car battery charger. Found the proper heat level and let it run for about 20 minutes to make sure the tied ends aren't getting hot.

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< Message edited by critterhunter -- 1/16/2008 6:44:51 PM >

_____________________________

If you believe in Global Warming then shut your mouth. All that hot air is warming up the planet, remember?

(in reply to critterhunter)
       Post #: 9

RE: Here's A Simple & FREE First Foam Build Plan! (Part 2) - 1/16/2008 7:02:49 PM   
critterhunter



Posts: 2529
Joined: 9/24/2004
From: Brook Park, OH, USA
Status: offline 		Now that the tools are covered will get to cutting out the wing. You only need the bow, but even without that you can make this plane by cutting the foam with a hacksaw or something. However, that will get messy and you'll also need to sand body parts more without a hot wire cuttere.

Below you'll see the wing jigs attached to a board. Notice the numbers on the jigs. These aren't needed but rather are a good way to keep track of where one wire is versus the other end. It also helps if two people are doing the cut, having one person call out the number he's on so the other can speed up or slow down. It doesn't have to be perfect, but you do want to keep both ends fairly close. It'll require less or no sanding to smooth out the wing. The wood extending out from the bottom of the jig was intended to hold weights on to keep the board from moving. I later found out that just putting weights on top of the foam was more than enough, so it isn't needed.

I used handyboard to make the wing jig but anything will do that won't burn easily. There is also a better way to hitch the jigs to the board by drilling through the bottom of the board and