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Foam Frog Build
By Deadline on Mar 05 2010 Category:General

Foam has become an inexpensive and viable building material for electric R/C plans. It's durable, repairable and available from you local home improvement store in bulk. With the advent of Foam Safe CA super glues there is really no limit to the possible designs one can pursue.

There are literally dozens of plans available. A quick web search for Foamie Plans or Depron Foam Plans will return more than you can imagine. This will be a build of the Frog. Plans are available from FoamFly.com for $12.

I chose the Frog as my first foam build for several reasons. One It looked simple. Two: It looked like it would not take too long. Three: It is reported to be an easy flyer for park type environments.

The Plans and accompanying instructions are good. The pictures also help. Still you are building a plane from plans and not a kit. So, there is a good deal of cutting, shaping and forming to do. Learning to work with the foam can be a challenge if you have not work extensively in other materials. There is no real forgiveness when cutting the foam. It's right or you cut out another one. The plans come with "The Definitive Guide to Working with Fan-Fold Foam". This a 6 chapter (45 page) guide to foam building techniques. It covers tools, glues, sources, etc. If you have never built with foam before it's well worth buying at least one of Dan Schwartz plans to get the guide. It will save you time and money hunting for the right things.

The Frog has formed wings. These are wings that hold their shape. You can see this in the photos. To get formed wings you need a wing jig. This a jig that you put the cut wings into and then place in the oven for a about 10 minutes to heat to shape. After the foam comes out of the jig it will hold the shape no other forming needed. It's a cool trick.  Being my first foam plane I had to also build a jig. I will cover that step in a second article. But here what it looks like.

Wing Jig

The frog does build quickly. I think I spent one evening cutting out the patterns from the plans and the next night I cut the foam from the patterns.

The Tail was first and installing the hinges was the only tricky part. You have to have the right style hinges and control arms to work with foam but other than that it's the same process as working with balsa.

Building the body on it's side was different but easy to do. the body is tight. there is no extra room to work with. It's width is just enough for the servo and the are to move. The servos have to go one behind the other and not side by side. The placement is not 100% spelled out. I think mine are just a little to far back. Unfortunately you don't have the wing at this point to balance their placement with.

The motor pod is next. you really need all the parts at once  to make sure it all fits. There no room to come back and add the ESC later. Once the second side of the body goes on it's on.

 Once the motor is in place it's on to the servos. To make the line to the tail as strait as I could I mounted one right side up the other upside down. They are taped in with two sided tape. I used a small stick on one side to keep them from twisting loose from their own torque. When you feel you have got it all in place, tested and working, then glue the second side on. It seals it all in and there is no turning back. Even though the servos are only taped you would have to break the foam apart to get to one if you had to change one out.

Well, maiden flight in the back yard. Had to add weight to the nose to get it to balance out. But a few washers and it drifts along just fine. We are ready for the park.

Total time to for this build was several weeks. The wing jig took at least a week to work out. I didn't track the cost but it wasn't as inexpensive as one would have thought. Since the first time, I had to buy a lot of the tools to do the job. Most of the R/C gear, batteries, ESC, motor and so on can be bought on-line. However you are buying ala carte. A motor from here, receiver here, control arms and props from somewhere else. The start up cost was probably equal to buying an ARF with it all in the box. Now that said the second and third one will have all most no cost as I now have supplies for about ten plans. I would rate the difficulty as Medium to High. This is not for beginners. You have to know where you are going, know how you are going to get there and when you don't you have to work it out on your own. There is no store to take it back to or support line to call.

Here are some stats on other Foam Plane options I considered from their Plans:

Plane Plan Motor Wing Span Prop ESC Batt Servos
ElectriFly RimFire 22M-1000 Brushless 31" 10x3.5 8-Amp 3-cell 350-700mAh Micro
Frog GWS IPS-A (5.86:1 Gear Ratio) 34" 9x7 GWS ICS-50 2-cell 120mAh LiPo GWS Pico BB or Hitec HS-50
Old timer GWS Dual IPS-A (5.86:1 Gear Ratio) 44" 11x4.7 GWS ICS-100 2-cell 700/1200mAh Lipo GWS Pico BB or Hitec HS-50
Staggerwing GWS IPS-A (5.86:1 Gear Ratio) 31.5" 9x7 GWS ICS-50 2-cell 1020mAh GWS Pico BB or Hitec HS-50
Tinabob 2 GWS EDP-50XC    Carbon Brush 24" 3x2 GWS ICS-100/100E 2-cell Li-ion 7.2v GWS Pico
Pond Baby 280 brushed motor 27-32" 6   8.4v 600 to 800mAh 2 micro or nano
Pelican GWS EPS-300c "2S" (2.80:1 Gear Ratio) 42" 7x6  GWS ICS-300 2-cell 1200mAh LiPo GWS Pico or Hitec HS-50

 With so many other good plane plans available to build, I'm sure I will have more to write about soon. I just need to pick my next project. Happy flying!

 
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