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FT MICRO Sportster! A scratch-build, no DTFB project/

#1
Greetings!

I'm an American living in Taiwan, where there is no Dollar Tree and thus no DTFB. And Flite Test doesn't ship here, so everything I do is scratch built. We do not have paper-backed foam board here at all, but we do have 5mm and 3mm paperless board.

I teach STEM at an international school here, and for two years I have been teaching a Flight Science class where we learn about the principles of flight by scratch-building FT planes (EZ Glider and Sparrow) using Experimental Airlines's technique of laminating the paperless foam with packing tape.

Today I'm showing off the start of my pet project: the MICRO Sportster. It is scaled down Mini Sportster for ultimate cuteness!

Because the foam here is 5mm (slightly larger than 3/16") and 3mm (significantly smaller), there's always a certain amount of adjustment that has to be done to make FT plans fit. In this case, however, I've taken the standard Mini Sportster plans and shrunken them down to 63% of the original: the difference between 3mm and 4.7625mm (3/16 in). What results is an almost half-scale Mini Sportster that is incredibly adorable!

The first step I did was to print out the Mini Sportster A-plans at 63% scale, and then tape them together and glue them to card stock. We get large sheets of pretty sturdy card stock from the local stationery store... in fact, everything I build with comes from the local stationery store, which are popular stores all over Taiwan. Every public school has at least a couple nearby, so supplies are pretty easy to come by.

This is what the plans look like after they've been printed, pasted, and cut out.
IMG_20191221_135551.jpg
For size reference, there's a glue stick in there, and the measurements at the bottom of my cutting mat are centimeters. Spoiler Alert: It's small.

I'm doing everything by hand, so cutting out accurately is exceedingly important, particularly at this scale. A little misalignment makes a big difference when your whole airplane is is only 37cm wingspan and 30cm long!

Here's a view of the two gauges and the tiny tiny Micro Power Pod in my hand. Aren't they just blinking adorable??
IMG_20191224_175932.jpg

For decorating, since the whole thing is going to be covered in packing tape, all the color goes directly on the foam. Using only ball-point pen, permanent black marker, and a yellow dry-erase marker, this is the color scheme I've come up with (so far) for the plane. Ironically, the yellow marker was purchased on my last trip to the US... at a Dollar Tree.
IMG_20191224_164224.jpg

It's very interesting to be working at this scale, and while I don't even know if it's going to be possible for it to fly, since the Reynolds value for the wing is affected by wing area, I hope at least to show it to my students as an example of what can be achieved with foam board when using great patience and care.

I will update with more pictures as the build progresses, and I would love any feedback you have on my little pet project!
 

mach1 rc

Well-known member
#3
Greetings!

I'm an American living in Taiwan, where there is no Dollar Tree and thus no DTFB. And Flite Test doesn't ship here, so everything I do is scratch built. We do not have paper-backed foam board here at all, but we do have 5mm and 3mm paperless board.

I teach STEM at an international school here, and for two years I have been teaching a Flight Science class where we learn about the principles of flight by scratch-building FT planes (EZ Glider and Sparrow) using Experimental Airlines's technique of laminating the paperless foam with packing tape.

Today I'm showing off the start of my pet project: the MICRO Sportster. It is scaled down Mini Sportster for ultimate cuteness!

Because the foam here is 5mm (slightly larger than 3/16") and 3mm (significantly smaller), there's always a certain amount of adjustment that has to be done to make FT plans fit. In this case, however, I've taken the standard Mini Sportster plans and shrunken them down to 63% of the original: the difference between 3mm and 4.7625mm (3/16 in). What results is an almost half-scale Mini Sportster that is incredibly adorable!

The first step I did was to print out the Mini Sportster A-plans at 63% scale, and then tape them together and glue them to card stock. We get large sheets of pretty sturdy card stock from the local stationery store... in fact, everything I build with comes from the local stationery store, which are popular stores all over Taiwan. Every public school has at least a couple nearby, so supplies are pretty easy to come by.

This is what the plans look like after they've been printed, pasted, and cut out.
View attachment 152029
For size reference, there's a glue stick in there, and the measurements at the bottom of my cutting mat are centimeters. Spoiler Alert: It's small.

I'm doing everything by hand, so cutting out accurately is exceedingly important, particularly at this scale. A little misalignment makes a big difference when your whole airplane is is only 37cm wingspan and 30cm long!

Here's a view of the two gauges and the tiny tiny Micro Power Pod in my hand. Aren't they just blinking adorable??
View attachment 152030

For decorating, since the whole thing is going to be covered in packing tape, all the color goes directly on the foam. Using only ball-point pen, permanent black marker, and a yellow dry-erase marker, this is the color scheme I've come up with (so far) for the plane. Ironically, the yellow marker was purchased on my last trip to the US... at a Dollar Tree.
View attachment 152031

It's very interesting to be working at this scale, and while I don't even know if it's going to be possible for it to fly, since the Reynolds value for the wing is affected by wing area, I hope at least to show it to my students as an example of what can be achieved with foam board when using great patience and care.

I will update with more pictures as the build progresses, and I would love any feedback you have on my little pet project!
Cool project 👍👍😎
 

Hondo76251

Well-known member
#4
I would think the packing tape over the paperless board would work well. I have removed the paper on the DTFB and put packing tape over it to increase strength without creating too much weight. It worked well for me.

Trimming and flying micro things is always more of a challenge. Here's one of my attemps:

 
#5
I would think the packing tape over the paperless board would work well. I have removed the paper on the DTFB and put packing tape over it to increase strength without creating too much weight. It worked well for me.

Trimming and flying micro things is always more of a challenge. Here's one of my attemps:

Insightful. What motors were you using to power that plane? And does anyone have good suggestions for a good powerplant for my single-engine plane?
 

Tench745

Well-known member
#7
The first step I did was to print out the Mini Sportster A-plans at 63% scale, and then tape them together and glue them to card stock. We get large sheets of pretty sturdy card stock from the local stationery store... in fact, everything I build with comes from the local stationery store, which are popular stores all over Taiwan. Every public school has at least a couple nearby, so supplies are pretty easy to come by.

This is what the plans look like after they've been printed, pasted, and cut out.
View attachment 152029
For size reference, there's a glue stick in there, and the measurements at the bottom of my cutting mat are centimeters. Spoiler Alert: It's small.

I'm doing everything by hand, so cutting out accurately is exceedingly important, particularly at this scale. A little misalignment makes a big difference when your whole airplane is is only 37cm wingspan and 30cm long!

Here's a view of the two gauges and the tiny tiny Micro Power Pod in my hand. Aren't they just blinking adorable??
View attachment 152030

For decorating, since the whole thing is going to be covered in packing tape, all the color goes directly on the foam. Using only ball-point pen, permanent black marker, and a yellow dry-erase marker, this is the color scheme I've come up with (so far) for the plane. Ironically, the yellow marker was purchased on my last trip to the US... at a Dollar Tree.
View attachment 152031

It's very interesting to be working at this scale, and while I don't even know if it's going to be possible for it to fly, since the Reynolds value for the wing is affected by wing area, I hope at least to show it to my students as an example of what can be achieved with foam board when using great patience and care.

I will update with more pictures as the build progresses, and I would love any feedback you have on my little pet project!
Can't wait to see how this one turn out.
A slight correction, Reynolds numbers are derived from speed, wing chord, and air density. Area is not part of calculating Reynolds numbers. Of course, area scales by the square, so your 63% size plane has only about 40% of the wing area of the original.
 

Hondo76251

Well-known member
#8
Insightful. What motors were you using to power that plane? And does anyone have good suggestions for a good powerplant for my single-engine plane?
That plane uses two 8mm brushed motors from a small toy quad. It is powered by a banggood micro receiver with built in 2 amp esc. With something as small as yours, so long as you can keep the weight down, that same receiver and a single 8mm motor with gear drive (like this)
https://m.banggood.com/Coreless-Red...86.html?akmClientCountry=America&rmmds=search
might do the trick. Certainly wouldn't be over powered but it is a cheap way to go...

If you want a little more oomph I would think something like an 1106 brushless would do the trick.

Think I listed all the parts I used in the build video of that little comet
 
#9
Construction continues on the MICRO Sportster. Detailing at this scale takes a lot of patience, as demonstrated by this series of photos hand-drawing a checkerboard pattern on the underside of the stab in 5mm squares:
IMG_20191226_092818.jpg IMG_20191226_100310.jpg IMG_20191226_105856.jpg IMG_20191226_113926.jpg

I feel like it came out pretty good. Here it is with the completed vertical stabilizer as well:

IMG_20191226_145456.jpg IMG_20191226_145602.jpg

Feedback always welcome!
 
#11
That little hot rod looks like its already doin 90mph! Nice build, I like it.

How do you do your hinges, tape?
I have experimented with just squishing the foam to make hinges, but on something this small, I think I'll need to make traditional bevel cuts. Especially on the elevator, I need it to be as free as possible to get both sides to move the same amount. Here's an example of an FT Commuter that I'm also making right now, where the hinges are just indented foam and surface tape:

IMG_20191226_163832.jpg
 
#12
Working in paperless foam has its own challenges, particularly in FT plans that utilize the paper backing to connect or align one piece to another, such as in the Sportster's main fuselage. Here you can see that for the MICRO Sportster, I have laminated only the outside of the airplane with tape, leaving the inside raw to reduce weight. In the nose doublers, the inside face is laminated, which provides enough reinforcement for the crumple zone. My belief is that in a plane of such small weight, this will be plenty sufficient to give rigidity.
IMG_20191227_091903.jpg IMG_20191227_091918.jpg

After trimming out the piece. You can see where the remaining tape acts as the paper from the original design, but at this point the tape has lost its stickiness, so if I keep those bits, I'd have to glue them down, adding to the weight.
IMG_20191227_103536.jpg

Since those edges are going to be under the battery door, and the edge of unpapered foam is straight and doesn't have the burn-relief of a speedbuild kit, I am thinking I will probably cut those back.

Speaking of the battery door, here's a shot of the cockpit interior, with the world's tiniest instrument panel hand-drawn by me. I am certainly no miniatures artist and I have no idea how those people who paint miniatures can be so incredibly detailed, but I'm very entertained by these tiny details which probably no one will ever see, but at least I know it's there.
IMG_20191227_103522.jpg

More to come!
 
#14
The project had a minor setback, as scratch-building always has fiddly alignment issues, and working at this scale exacerbates any inaccuracies. On the fuselage, when cutting out the channels, any imperfection in the width of the cut results in the center pieces being too narrow for the power pod:
IMG_20191227_131040.jpg

So I made the decision to remove the center section entirely.

IMG_20191227_131144.jpg

This had the unforeseen advantage of allowing me to put both fuselage sides together, and discover some pretty significant misalignments that I was able to fix now before they gave me a crooked wing later.

IMG_20191227_131922.jpg

Here are the re-crafted parts, individually cut from a single sheet of the correct width, to ensure that all parts are uniform and can accommodate the width of the power pod and doublers.

IMG_20191227_134747.jpg

More to come later! I've actually made more progress, but I need to get documentation together. I emphasize the importance of documentation to my students, which is why these posts are so wordy :)
 
#17
I would just be careful when choosing the power set up for that. It looks like it would be crazy fast.
I'm open to any specific suggestions anyone has. I'd really like to have a plane as slow as the wing will sustain... but yeah the farther I go, the more I'm worried that's not going to happen :) I thought I'd build small so I could fly it in the school's gym, but if it ends up a rocket... it might be beyond my piloting skill. But no matter; it's about the build for me.

I glued up the top rails of the fuselage, work is coming along. Looking back on it, I think I should have waited to glue the turtledeck former, so that I could still lay it on its top to glue in the bottom panels. But I have a workaround planned for that.
IMG_20200102_145548.jpg
 

The Hangar

Well-known member
#18
I'm open to any specific suggestions anyone has. I'd really like to have a plane as slow as the wing will sustain... but yeah the farther I go, the more I'm worried that's not going to happen :) I thought I'd build small so I could fly it in the school's gym, but if it ends up a rocket... it might be beyond my piloting skill. But no matter; it's about the build for me.

I glued up the top rails of the fuselage, work is coming along. Looking back on it, I think I should have waited to glue the turtledeck former, so that I could still lay it on its top to glue in the bottom panels. But I have a workaround planned for that.
View attachment 152997
It looks really cool! I can't wait to see it fly!
 
#19
Sorry I have not updated in a while. We've been preparing for Finals, including my students completing their Sparrow's Egg Challenge (FT STEM teachers will know what I mean). So work has slowed on the MICRO Sportster.

I do have two pictures to show, of the wing construction, which I actually completed a while ago. In order to save weight, I've only laminated the outside surfaces of the wing, so indenting the guide lines on the inside of the wing is very easy with just a barbecue skewer:
Wing 1.jpg

Here's the completed wing, with the ailerons already score-cut.
Wing 2.jpg