Babydoll 21" Scratchbuild (the hard way)

[speedbirdted]

Hats off, I'm truly impressed (and in general a big fan of own design you brilliantly achieved).

May I ask for some more on how you did the logo ? In particular very impressed by the finesse of the line between the eyes.
Is it out cut from black sticker? covering film ?
Once out cut how did you apply it on the wing ? Did you use a secondary "apply-tape" ??
And How, and how and how ...

You see, for me what you achieved is still a mystery.

I cut the Felix decal and all the registration numbers out of black ultracote. I wanted to use something like self-adhesive vinyl but the only stuff I had available like that was silver and just wouldn't have looked right. To make the covering film easier to make precise cuts in, what I'll usually do is adhere it to some non-porous material (foamboard is great for this but just paper will suffice in a pinch, and plywood also works okay) at low temperature, so it can be easily peeled back off once you are done cutting it. The material has to be non-porous as this will both help it not adhere as strongly and be easier to pull off, and will not leave bits of material stuck to the covering afterwards which will impact its adhesion strength when you apply it to the actual plane.

Here is a series of pictures documenting the process, to cut out some window decals for another airplane I built several years ago. On the right is the covering adhered to foamboard, on the left is the template made from paper, and on the top is a set of cut out windows ready to be peeled off. This was taken in between making two sets of windows; normally I do not cut out the template prior to cutting, instead I put the template on top of the covering and cut straight through it, cutting out the decals in the process.

The Felix logo I did not get right on the first try. Not even close Eventually I found the trick to getting the very thin precise lines around the eyes and mouth was to take my X-acto blades and sharpen them considerably with a stone, and then they would cut much better. I also experimented with heating them with a torch as this can allow much less pressure but it ended up burning the template so this idea was rejected.

In other news I worked on the cockpit some. I printed off some gauges, but I'm not super happy with how they look. Inkjet printers just don't have the necessary resolution to make them look nice, but there's no way in hell I could hand paint them this small so I'll just have to live with it. The gauge rims are made of delrin; I hand cut them out with a piece of music wire I heated red hot with a torch and lots of patience. I tried to laser cut them but delrin is awful to cut as it melts and gets gooey (and smells oh so awful) Simulated glass was made with saran wrap to cover the gauges. The reflection off of it looks nicer than the actual gauge...

I tried also to make some switch-looking things with music wire as well as a throttle out of an old very dull pin (I have a whole box of those) The switches don't look that great but you really have to concentrate in order to notice them.

I'm still looking for a pilot....

From this angle you can also see the ugly and disgusting cockpit edge. Unfortunately it appears my plan to cover it with a piece of fuel tubing won't be implemented because I couldn't actually find a paint that would stick to it. It kept flaking off every time I tried to bend the tube even a little. I think I'll just hide it with covering material...

 

[hsquier]

Thank you ++ for the trick. So patience and delicacy are the main words.

 

[Crawford Bros. Aeroplanes]

I cut the Felix decal and all the registration numbers out of black ultracote. I wanted to use something like self-adhesive vinyl but the only stuff I had available like that was silver and just wouldn't have looked right. To make the covering film easier to make precise cuts in, what I'll usually do is adhere it to some non-porous material (foamboard is great for this but just paper will suffice in a pinch, and plywood also works okay) at low temperature, so it can be easily peeled back off once you are done cutting it. The material has to be non-porous as this will both help it not adhere as strongly and be easier to pull off, and will not leave bits of material stuck to the covering afterwards which will impact its adhesion strength when you apply it to the actual plane.

Here is a series of pictures documenting the process, to cut out some window decals for another airplane I built several years ago. On the right is the covering adhered to foamboard, on the left is the template made from paper, and on the top is a set of cut out windows ready to be peeled off. This was taken in between making two sets of windows; normally I do not cut out the template prior to cutting, instead I put the template on top of the covering and cut straight through it, cutting out the decals in the process.

View attachment 194529

The Felix logo I did not get right on the first try. Not even close Eventually I found the trick to getting the very thin precise lines around the eyes and mouth was to take my X-acto blades and sharpen them considerably with a stone, and then they would cut much better. I also experimented with heating them with a torch as this can allow much less pressure but it ended up burning the template so this idea was rejected.

In other news I worked on the cockpit some. I printed off some gauges, but I'm not super happy with how they look. Inkjet printers just don't have the necessary resolution to make them look nice, but there's no way in hell I could hand paint them this small so I'll just have to live with it. The gauge rims are made of delrin; I hand cut them out with a piece of music wire I heated red hot with a torch and lots of patience. I tried to laser cut them but delrin is awful to cut as it melts and gets gooey (and smells oh so awful) Simulated glass was made with saran wrap to cover the gauges. The reflection off of it looks nicer than the actual gauge...

I tried also to make some switch-looking things with music wire as well as a throttle out of an old very dull pin (I have a whole box of those) The switches don't look that great but you really have to concentrate in order to notice them.

I'm still looking for a pilot....

View attachment 194531

From this angle you can also see the ugly and disgusting cockpit edge. Unfortunately it appears my plan to cover it with a piece of fuel tubing won't be implemented because I couldn't actually find a paint that would stick to it. It kept flaking off every time I tried to bend the tube even a little. I think I'll just hide it with covering material...

You could use some brown wire insulation

 

[speedbirdted]

It's a bit belated but I did actually get around to maidening the subject of this thread.

It's terrifying!

I thought my Littlest Stick which has the same engine was quick... but oh boy this thing is just on a whole nother level in terms of speed. It is definitely an airplane that allows no relaxation at any time. Normally I like airplanes with these kinds of characteristics because they can be stupid fun to toss around once you get the hang of their handling. However... the sad thing is, this is just not a fun aircraft to fly.

The reasons for this are mainly due to the unholy combination of very short engine runtime and poor glide ratio. Ever wonder why Cox engine powered airplanes don't have wing cube loads in the double digits? (This one came out to 13.3, well into warbird territory) Every time you land, you are a glider. There is a reason gliders don't have warbird wing loadings! The glide ratio of this airplane is brick tier. Trying to turn it in a glide is even scarier - I don't dare test the tip stall characteristics of it, but I'm betting it's vicious.

Just about every flight with this airplane that hasn't resulted in an off-airport landing (so far, two of four) has consisted of climbing like a homesick angel and then maintaining an incredibly tight pattern almost directly over the runway, and hoping when the engine dies I can hit it on the glide home. My club field actually has a quite spacious 700' x 60' runway... with a grass surface. The wheel pants don't like grass, and they protest that by leaving the airplane. There's also a substantially narrower and smaller 300' x 30' geomat section which is what I have to try and land on every time.

The other problem is the engine, more specifically the fuel tank. Entirely filling it gets me a minute at best, and the fact that the point at which the engine dies is so random makes straying very far from the runway very uncomfortable due to the aforementioned glide ratio issue. If only Cox at some point had the idea to make a Peewee 020 with a larger tank like they did with the Golden Bee and Texaco 049s it would solve this problem entirely but unfortunately to my knowledge they never did. I suppose I could solve this problem by changing it out for a backplate with a fuel nipple but then I would have to cut the fuselage into a bunch of pieces to mount an external tank in the fuselage. This is not something I feel like doing.

But there's a silver lining: the whole reason this airplane is no fun is really just because of that damn tiny fuel tank. The wing loading is annoying, yes, but it's only really a problem when you don't have the luxury of power-on landings. This airplane actually doesn't really have any outstandingly weird handling characteristics. It's actually pretty neutral all around. I expected it to be a twitchy, longitudinally unstable death machine due to the vertical stabilizer (lack thereof) and the short coupled tail but once I got it trimmed out (which took three whole flights!) it actually handled remarkably well, even though the only thing I could really do with it to make sure it would make it back home was aerial NASCAR over the runway.

So, the Babydoll is retired to permanent ceiling storage. It looks too nice there to risk smashing it into a million pieces. But... I'm not content with abandoning the design entirely just yet.

I'm not sure why I didn't think to do this until now. Literally all I did was take the external dimensions, scale everything to 200% and then just redesigned the internals accordingly. Nothing is re-scaled out of proportion with the original, and I don't think anything needs to be. The fuselage design internally is actually pretty much the same just with more formers and longerons in some places, to prevent the "starved horse effect" that cropped up in a few places on the original. The wing and tail are very different internally but externally the same - the horizontal and rudder are all stick built now and the wing has more sheeting and three sections to fit better on the fuselage (not sure why I didn't also do this on the original)

Wingspan scales out to 44", 42" if you forget about the wingtips (like I did originally when writing the thread title, the original Babydoll is actually a 22" span) and wing area comes to 351 square inches. With a projected AUW of 3 pounds this gives a cubed wing loading of 12.6, which is about the same of the original.

For power I think I'm going to use my trusted OS 25FP. It's a reliable lightweight motor with great power for it's size and it should haul the mail reasonably well if I can keep the AUW reasonably close to my prediction. It also has a throttle!!!!!!!!! (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) I considered a larger motor but the fact that the largest fuel tank I can fit in it is about 4 ounces that quickly put the kibosh on that idea.

 

[Matthewdupreez]

It's a bit belated but I did actually get around to maidening the subject of this thread.

It's terrifying!

I thought my Littlest Stick which has the same engine was quick... but oh boy this thing is just on a whole nother level in terms of speed. It is definitely an airplane that allows no relaxation at any time. Normally I like airplanes with these kinds of characteristics because they can be stupid fun to toss around once you get the hang of their handling. However... the sad thing is, this is just not a fun aircraft to fly.

The reasons for this are mainly due to the unholy combination of very short engine runtime and poor glide ratio. Ever wonder why Cox engine powered airplanes don't have wing cube loads in the double digits? (This one came out to 13.3, well into warbird territory) Every time you land, you are a glider. There is a reason gliders don't have warbird wing loadings! The glide ratio of this airplane is brick tier. Trying to turn it in a glide is even scarier - I don't dare test the tip stall characteristics of it, but I'm betting it's vicious.

Just about every flight with this airplane that hasn't resulted in an off-airport landing (so far, two of four) has consisted of climbing like a homesick angel and then maintaining an incredibly tight pattern almost directly over the runway, and hoping when the engine dies I can hit it on the glide home. My club field actually has a quite spacious 700' x 60' runway... with a grass surface. The wheel pants don't like grass, and they protest that by leaving the airplane. There's also a substantially narrower and smaller 300' x 30' geomat section which is what I have to try and land on every time.

The other problem is the engine, more specifically the fuel tank. Entirely filling it gets me a minute at best, and the fact that the point at which the engine dies is so random makes straying very far from the runway very uncomfortable due to the aforementioned glide ratio issue. If only Cox at some point had the idea to make a Peewee 020 with a larger tank like they did with the Golden Bee and Texaco 049s it would solve this problem entirely but unfortunately to my knowledge they never did. I suppose I could solve this problem by changing it out for a backplate with a fuel nipple but then I would have to cut the fuselage into a bunch of pieces to mount an external tank in the fuselage. This is not something I feel like doing.

But there's a silver lining: the whole reason this airplane is no fun is really just because of that damn tiny fuel tank. The wing loading is annoying, yes, but it's only really a problem when you don't have the luxury of power-on landings. This airplane actually doesn't really have any outstandingly weird handling characteristics. It's actually pretty neutral all around. I expected it to be a twitchy, longitudinally unstable death machine due to the vertical stabilizer (lack thereof) and the short coupled tail but once I got it trimmed out (which took three whole flights!) it actually handled remarkably well, even though the only thing I could really do with it to make sure it would make it back home was aerial NASCAR over the runway.

So, the Babydoll is retired to permanent ceiling storage. It looks too nice there to risk smashing it into a million pieces. But... I'm not content with abandoning the design entirely just yet.

View attachment 205340

I'm not sure why I didn't think to do this until now. Literally all I did was take the external dimensions, scale everything to 200% and then just redesigned the internals accordingly. Nothing is re-scaled out of proportion with the original, and I don't think anything needs to be. The fuselage design internally is actually pretty much the same just with more formers and longerons in some places, to prevent the "starved horse effect" that cropped up in a few places on the original. The wing and tail are very different internally but externally the same - the horizontal and rudder are all stick built now and the wing has more sheeting and three sections to fit better on the fuselage (not sure why I didn't also do this on the original)

Wingspan scales out to 44", 42" if you forget about the wingtips (like I did originally when writing the thread title, the original Babydoll is actually a 22" span) and wing area comes to 351 square inches. With a projected AUW of 3 pounds this gives a cubed wing loading of 12.6, which is about the same of the original.

For power I think I'm going to use my trusted OS 25FP. It's a reliable lightweight motor with great power for it's size and it should haul the mail reasonably well if I can keep the AUW reasonably close to my prediction. It also has a throttle!!!!!!!!! (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) I considered a larger motor but the fact that the largest fuel tank I can fit in it is about 4 ounces that quickly put the kibosh on that idea.

can't wait. hope it has a longer flight time than the first

 

[TooJung2Die]

It's a bit belated but I did actually get around to maidening the subject of this thread.

It's terrifying!

It makes me smile to think of this tiny 22" airplane with a .020 Cox engine screaming around the field like an angry hornet. That must get your heart rate up there. All of a sudden, phut! the engine dies turning it into a lead balloon. Yup, she flies! Next project. Great report!

 

[cyclone3350]

What an absolutely stunning example of an Ole' School project. Very nice indeed.

 

[Tench745]

Love it, can't wait to see the Babydoll 2!