“Aero Car” 3d printed, peewee powered plane build

Okay guys, here is 1.8 complete with tail boom and cowl. Currently in 1.8 the tail boom prints in 2 sections, I have also printed a dummy 3x3 rod to help hold things together with this version. The cowl is held on with painters tape currently. So far everything seems sturdy enough. There are a few issues to work out but those are more related to printer tuning, which I plan on ironing out once I have the actual material for the airplane. Anyway, here are a few photos of the model as it sits. It’s now orange, I changed to a different color because I was having extrusion issues with my black pla due to moisture issues.

Looking good Kyle

KyleRManeti95 wrote:Thank you buddy. I just measured the port face to the inside face of the cutout in the cowl and the minimum distance in that region is just shy of 4mm. I’ve been a little bit worried about the exact issue that you are mentioning. I’ll have todo some test runs to really determine how things will hold up in that area. If all else fails I could always either change the design of the cowl to better compensate for heat, or find a material that can withstand higher temps.

Kyle, the heat impact by the exhaust gases can be mitigated with an add-on shield that I cut from a beer can, see below my TeeDee010 whose tank bowl had to be replaced after the hot exhaust gases emitted through the rear exhaust port melted it.

The shield should not lay flat on the surface to be protected (especially because aluminum conducts heat very well), but a very thin air gap - constantly flushed and cooled by propeller air - should remain between the shield and plastic surface..this add-on aluminum shield - weirdly primitive in context of a 21st century 3D printed aero plane - may compromise the elegant look of your 3D printed beauty, but still maybe worth it, and seeing your skills I figure it could be nicely fashioned after some thoughts from you. Maybe you can hold it down with a tab on it, tucked between the firewall and the PeeWee tank backplate like I fixed it on the photo below?? The free sides of your shield parallel with the fuse wall could extend to just a tad short of the cowl walls for providing the air gap?




So if you "line" the plastic cowl with  thin aluminum sheet that does not touch the cowling wall, you are all set against the hot engine exhausts destroying your beautiful plastic plane. The extent of lining needed depends on the exhaust port orientation of your PeeWee, of course.

I see what you are saying balogh. I’ll see what I can do with the cowl, the exhaust ports are facing forwards and back just like in the cad model posted earlier. I’m sure I can devise some sort of shroud that fits inside the cowl made from aluminum cans. Maybe I could 3d print a former to help shape the aluminum to fit the cowl much better. With the cad models I can pretty much reproduce any shape I need to as a Separate part.

As for a model update, I am currently printing fuselage v2.0. In this version I have crude pockets meant for landing gear, I added these pockets into v1.9 but they were far too snug. I also have bent up a set of landing gear from 1mm ss wire, I did not model anything before hand and just went by feel with my multi tool and a scale. I have also updated the tail boom to include the mount for the stabilizer. Unfortunately the way I have things oriented the parts do not print properly. Another thing that I’ve done is printing out the rear stabilizer. I left the stabilizer as a solid model in my cad program, exported into the slicing software and I let the software fill in the blanks. The result is a stabilizer half that prints with 2 walls and 10% infill to five the model some strength.
My next step will be to finalize how the tail boom gets printed, modify designs slightly to help make the assembly easier, and hopefully make for a stronger airplane.
Unfortunately I do not have any numbers to share as to weight of new components being printed but I will be posting some pictures in about 3 hours once the new fuselage prints.

Okay I’m back. Since my last post a few hours ago fuselage v2.0 has finished printing and I have assembled the various parts together, the 1mm ss wire fits a lot better in this new updated version.
I have also completed a bit of work on the tail boom, stabilizer and cowl.
First, with the boom I have merged the two sections together, I’m hoping this will help final assembly, but I’m not sure how printable the tail boom is for version 2.1.
Second, I have modified the middle face of the stabilizer. It is now parallel to its respective axis and no longer aligned with the center line of the fuselage. I have done this in order to more the middle of the stab out 2.5mm from center, which will allow me to print the section of the boom which who’ll receive the stabilizer halves.
Third, I have further modifiers the boom design to incorporate the stab mount, currently the stabilizers will slide into pockets and held in with glue.
Fourth, I have changed the angle of the rear landing gear 15 degrees to allow a smoother line to the ground, with fuselage 2.0 the rear gear is almost vertical in position so this realignment should push the rear wheels out a smidge more. I will have to modify the gear leg lengths to allow the model to sit level on the ground.
Last, I have modified the cowl and have also modeled in a simple shroud, I’m not sure how well this design will work so I’d like any input you guys can offer me. I still have to sort out mounting the shroud as well as cowl mounting.

Here is one last photo detailing the shroud. In the first photo only half is shown. In this last photo you can get a glimpse into one of my favorite things with 3d modeling. If both sides of a part are symmetrical, you only have to model half of the part and mirror to the other side. Another awesome thing, if your part has a common feature type that can be found all over the model. Don’t waste your time modeling the part over, make copies of said feature and multiple x amount of times required, place in correct location, done.

For the shroud, I am thinking I can 3d print a mold to shape the aluminum around it and form the correct shape. This will help give some repeatability and simplify the manufacture of the shroud if other people want to build this model In the future. What are your thoughts?

KyleRManeti95 wrote:For the shroud, I am thinking I can 3d print a mold to shape the aluminum around it and form the correct shape. This will help give some repeatability and simplify the manufacture of the shroud if other people want to build this model In the future. What are your thoughts?

Your shroud design is very professional.

As long as you keep the shroud sufficiently away from the exhaust port - so that it should not act like a closed muffler -,  thus allowing fresh air intake for the SPI engine under its piston skirt, this is OK.  With my limited skills and infrastructure, in lack of 3D printer, I would simply cut an aluminum sheet (from a beer can), bend it 90 degree, and put one half (like a short tab) between the firewall and the engine backplate, the other half shrouding the plastic cowl walls from the hot gases. I would repeat it for the other side/exhaust port, too. Now that your actual exhaust port position is as shown in the drawing i.e. exactly aft and forward, the situation if not soo critical, the hot exhaust at the rear will be blown on the fuel tank..., and it will be mixed with fresh propeller air before it hits the plastic firewall, with probably no melting effect. But for another - maybe future replacement - Pee Wee where the exhaust port orientation may be  different i.e. sideways, the shroud may still be worth it. Very old stock COX engines - especially those with thin cylinder wall - were carefully produced with threads on cylinder and crankcase tapped such that the exhaust porting was parallel with the shaft (see my old stock 010 TeeDee of 60+year age on my photo above). Later engines did not see that exact port orientation, that became random, as more and more cost cutting measures were needed.

Kyle, You may find this information useful. The forum has a longstanding member @Jason_WI who also has a 3D printer and has printed backplate/carbs to fit the Cox Pee Wee .020 engine. Here's the thread..







Below are photos of one that he printed, which I received as a contest-prize a few years ago.





The other (light-colored) piece is a conversion-mount for the early Cox .049 "Postage-Stamp" product-engine carb that otherwise had no mounting-provisions for use in an aftermarket model kit. Goldberg Models used to offer these.

Thankyou Roddie and Balfour. I’m going to experiment with a coke can later tonight to see what I can come up with, I’m going to still follow this pattern but I’m going to implement some of the features you’ve mentioned about mounting. Perhaps the engine and shrouds could be mounted inside the cowl then fixed to the front of the airplane. This might help reinforce the nose of the airplane a bit and solve the cowl mounting issue.
Roddie, thank you for posting those pictures and the link to Jason’s thread, that is the exact backplate that I would love to incorporate into this model. The skycopter backplate is okay, I have modified it to remove the fins from the back and it still needs to be flattened. I only have needle files and a 1” file in my multi tool so I’m somewhat limited.
Do you know if that backplate when bolted to the back of the peewee makes for the same length of a standard peewee? I feel I may run into some small fitment issues soon because of the skycopter backplate so I’d like to start sorting that issue soon.
I’m also starting to think about the electronics access hatch, I’d like it to be on the bottom of the plane, perhaps a door that swings down to allow access to the battery. Another access point could be from the top of the fuselage to access servos/ reciever/ tank. But if I also make the hatch in the bottom large enough I could accomplish all of this at the same time and leave the top of the model solid.

I am currently printing v2.1 of the tail boom. I will report with progress later. As of right now though, here is how the tail boom looks.
The narrow structure behind the larger one is the tail boom, the larger structure is support material. I’m hoping that this support will allow me to successfully print such a long, narrow part with a large mounting surface at the top of the print. Wish me luck guys lol.

If I had the choice I would place the hatch rather on the top than on the bottom. My experience is the fine castor mist traveling in the air behind the engine, and the spent castor smear descending on the fuselage are prone to wetting fuselage internals easier with a hatch on the bottom than with the hatch on the top. This may be particularly true with engines inverted i.e having their cylinder hanging down. I am not sure how your wings will mount on the fuselage, but an open wing saddle on the fuse top can double as a hatch, too.

Thank you for pointing that out, I will have the hatch on top.
The wing still needs to be figured out. I’m thinking of doing the same process that I did for the stabilizer mount. Much like this.
I’m still not sure how exactly I’m going to hold everything together. Glue would be convenient as I could glue the entire airplane together and not worry about it. Down side would be if a wing broke, or if anything broke. This would mean the entire plane needs to be printed again, not terrible as the final airplane should take maybe 24 hours to print all the parts. I could use hardware to hold assemblies together and allow for part interchangeability which would be amazing and would save lots of time.
I’m going to sort the wing out tonight as well as some work to the shroud and any modification needed for the new tail boom that’s printing right now.

Okay I’m back with a quick update on the cad models for the aero car.
First, the tail boom was able to successfully print, although when removing the part from the print bed, the support material failed and caused the tail boom to snap. I will have to slightly modify the design of the tail boom to add in more stength.
Second, I have gone through and added in a rough wing mount very similar to the one for the tail boom. I also imported a previous version of the wing, with a correct airfoil.
Here is how everything is looking for fuselage v2.2

The total wingspan for this model is 24.829” or just over 630mm.
I’m still not sure what everything will weight as I’ve been working on a side project for my coworkers and I to cause a little mischief at work.. lol

Kyle,

The model looks fantastic... Just a humble question: do you need the fuselage to be so tall, with unwanted drag? I would size the height and width with consideration of what needs to go in there I.e battery, receiver, servos and a switch to turn the electronics on.

Even if you want only a "lazy" sports plane as you put it, saving weight and drag is always good.

I would trade in the weight savings for adding more reinforcement to the wing root attachment  area, like some more vertical ribs on the inside surface of the fuselage. An unwanted landing on the wing or getting the wind tip stuck in tall grass on landing may generate excessive moments on the wing root and attachment area of the fuselage...I do not say you will experience those mishaps, but if I built that nice plane for myself, I would think of those unlikely events.

Sorry for putting my nose into your design.

Looking Good !

Balogh, thank you for your suggestions. I see what you are talking about with how tall the fuselage is in comparison to the height of the fuselage. Up to this point I’ve largely followed the profile from the original drawings. I can, or should be able to mess with scale factors tonight. I should be able to scale the z axis separately from the other two axis in my program. But I do agree,a slightly shorter fuselage would be helpful in eliminating drag. Currently I have a receiver cad model that someone else has done the grunt work on. I still need to figure out what battery I’m going to use. What would you suggest?
I have also been thinking of the other issue that you’ve mentioned. Currently the wing root is around 2mm thick all around the wing. There is still a lot of room for improvement.
Currently I’m not too concerned about the weight of the model, as so much of the final weight #’s will change when I start printing the lw-pla. I’ve started to employ two methods of construction with the fuselage and other parts. Mainly due to how thin some parts are, I can’t hollow out all sections to have a .8mm wall thickness. I’ve modeled some areas hollow, and I’m leaving other things solid, like wing and stabilizer. I’m letting the slicing software figure those areas out with infill material. Because of this I can’t fully rely on the cad program to tell me accurate weights, the slicing software gets us close with pla but still isn’t the final number.
I have been having nightmares about a wing snapping so if definitely love to do all I can to mitigate that possibly.
As always, thank you for the feedback. I always appreciate it

Thank you getback

Kyle, sorry for my Hunglish that may have been misleading. I am actually talking about the "z" dimension of the fuselage I.e it's height that, when reduced, can save drag.

For battery the best thing I could recommend is a 400mAh 1 cell LiPo battery connected to the receiver via a small step up DC converter unit type: MT3608 that can ramp up the 3.7V nominal voltage to any level you want by setting it with a small screw, like 5V to match your servos. The power unit thus combined weighs only 14.7 grams without cabling, and the battery will sustain several 10 minutes flights between 2 charges..



For switch I would propose a super light Zepsus magnetic nano switch, that weighs less than 2 grams and is activated with a strong magnet swiped along the fuselage section behind which the switch sits.

https://mg-modellbau.de/battery-switching-et/Zepsus/Zepsus-Magnetic-Switch-Nano-DLG-HLG.html

I guess this is also sold in the US, it is made in Denmark

Hi Kyle, I'm fascinated with this build. I have an idea that may interest you.. regarding wheels (actually tires..) for your model. I'm known around here for my redneck applications.. and making things from materials that are cheap and easily sourced. One such item is wheels/tires for my models.

I'll get right to it.. I recently found/sourced a "pool-noodle" that was made from black foam.. (actually..not too common a color..) but was found at a local dollar $ store.



I've used pool-noodles to make tires. They're lightweight and offer terrific shock-absorbing properties.





You would want to "print" the wheels (hubs) I'm sure.. but I used a hardwood dowel.. and a Dremel-tool mandrel to "turn/shape" the foam tire.









Did I mention that they're lightweight?



I'm sure they're not for everybody... but I get a lot of satisfaction from making my own stuff when I can.

Your good balogh, I understand what you are talking about, I’m going to see what happens when I compress the z dimension a little bit later tonight to see what I can do. Thank for for also posting pics and a description of the battery and step up converter. I’ll add those to my bill of materials, what receiver are you using?
I’ve also been considering the zepsis switches, I’d like to minimize the amount of disassembly and reassembly of parts on the airplane and that would certainly help.

Thank you Roddie, I’m glad you are enjoying this build as much as I am it’s been a lot of fun getting to the point I’m at now.
Also thank you for posting the recommendation on using the pool noodles as tires, that’s a really fantastic idea. I wonder what the smallest diameter of this type of material I could get? The wheels on this airplane are about 1” in diameter. I also want to add, I really like your method for shaping the wheels, it’s such a simple solution that honeslty if I tried todo so, without any idea how. I would likely over engineer the heck out of forming that shape lol

That's a practical, creative way to make custom lightweight wheels, roddie.