Building with Dollar Tree Foam - Part 1 - Background.

Hi Everyone -

This is the first part of a series of articles I started on the old NAMC blog in the spring of 2017 which I wanted to post here on my new blog with some updates.
In April of 2017, I completed a Mig-35B built entirely from Dollar Tree foam (DTF) or Adams Readiboard.  I have built dozens of planes using paperless DTF for the KF airfoils, but never an entire build, so it was an experiment I had long wanted to try.

There are several reasons why I wanted to experiment and build an entire score and fold park jet from DTF -

• with Hobby grade Depron no longer available in North America, I wanted to explore another option other than Model Plane Foam (MPF);
• one of the NAMC Su-27 Flanker beta test pilots Peter (homey666 on the RC Powers forum) built an Su-27 with it and I was very impressed with not only how it looked, but how it flew; and
• it is always fun to experiment with new building materials as it makes me a better builder overall.

I had a few goals going into the build -

• I wanted the plane of course to look good which gave me a chance to experiment with sanding, finishing and painting a complete DTF build;
• The plane needed to be strong in order to hold up to my flying style, so I needed a nice strong wing and control surfaces without weighing the plane down.  My goal was to end  up in the 21-22 oz 595-624 gr range with a 2200 3S battery which is my "sweet spot" for planes for planes with most power setups I like to use; and
• since even in the summer time, I am often landing on wet grass, the plane needed to be waterproof and durable, again without it being too heavy.

Preparation

Peter had already shared some great build tips on the NAMC Su-27 Flanker design, build and test thread and I already had a few ideas from watching Flite Test build videos, however I wasn't exactly sure how I would be able to accomplish my goals listed above.  Fortunately, Peter graciously agreed to help me out, I found a set of Mig-35B plans tucked away in my closet and away we went.

I have a Dollar Tree store in another town about a half hour drive from me, so access to DTF is quite easy.  I procured a few extra sheets to add to my supply and was ready to start cutting foam.  Other supplies I already had and from testing I knew that all the glues I already use with Depron and MPF would work just fine with DTF.  I did need however to get some oil based Minwax to help in the water proofing and strengthening of those areas of the plane where I would be leaving the paper on the DTF.  

I also found and watched this video from Flite Test (please click on the link, the video is unlisted and I couldn't get it to upload from YT😒)to educate myself on how to use the Minwax to best protect my plane without harming the foam or adding excessive weight.

I cut out the parts for the Mig-35B and after carefully laying them out, determined I would need four (4) sheets of DTF to build this plane including the KF4 airfoils.  I will cover this in more detail in Part 3 of this series.

Cost analysis

Of course we are all probably looking for ways to build our planes better and cheaper, so how would this build compare to my other builds from a standpoint of foam costs?  Unfortunately, because I had to spend about $7 USD on a can of Minwax, it skews the results, but I'm sure I'll find something to use the Minwax for, perhaps another DTF build or two 😊

I still have several sheets of Depron I am hoarding, Depron costs me about $9 USD per sheet by the time it is shipped to my door.  MPF, I actually use Fli-Power Value XPS from RC Foam costs me about $5 USD per sheet shipped to my door.  The DTF costs me $1.25 Cdn or $1.00 USD based on today's exchange rate per sheet and I can buy it locally.

When building with Depron, I use MPF for the fuselage and canopy to save Depron and money.  These builds require -

• one full sheet of Depron - $9;
• 1/4 sheet of MPF - $1.25; and
• one sheet of DTF (for KF airfoils) - $1.00.
• Total - $11.25

When building entirely with MPF, my planes use about 1 and 1/4 sheets of MPF.

These builds require -

• one and 1/4 sheets of MPF - $6.25; and
• one sheet of DTF (for KF airfoils) - $1.00.
• Total - $7.25

Foam cost for building this Mig-35B entirely of DTF - $4.00.

With both MPF and the DTF I do need more reinforcement than with the Depron build, but I recycle sections of carbon fiber tube or use bamboo BBQ skewers I get from the Dollar Store which cost me about $0.01 Cdn each.

The DTF build did require a bit more glue to seal the edges of where the paper was left on, maybe 1/4 bottle of the Craft Medley glue I now use (a Foam Cure equivalent).  This glue costs me $1.00 USD and I can get it at my local Dollar Tree, so lets round up the DTF build cost to $4.10 not including the Minwax.

​So if I built a lot with DTF, it would be a very cost effective way to build financially and I can always get more foam locally without needing it shipped to me.

Before getting further into the build process, the next part of this series of articles will discuss my experimentation with Minwax.  As the use of Minwax was an entirely new building process for me, I wanted to do some experimenting before applying it to a completely built plane in case there were issues, so the next article will cover Minwax lessons learned.

Park Jet noise...the "other" sound of freedom😎
Cheers,

​Scott