telnar1236
Elite member
Thanks, now for the final question, does it actually fly
Looking for Ideas for 3D Printed Jets
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telnar1236
Elite member
Unfortunately, I'm under a TFR all the way through 1/4 so I won't be testing anything any time soon. However, the silver lining is that it gives me plenty of time to design and print. I have substantial portions of the tail for the Ghost printed now. I'm running out of the blue gray filament, so I've switched to a more normal gray for the fuselage.
I'm also looking at replacing the MiG 15/17/swept wing plane with a scaled down 3 channel version of my big 90mm F-106. I still have a whole spool of LW-ASA filament and I think anything short of a delta wing will not have enough rigidity with how soft and flexible this filament is. This will also be an experiment with vase mode printing since my earlier tests with it show that pretty much any print with retractions results in a print failure.
It should also be very light which should make it an excellent jet trainer, and it should also print well in LW-PLA.
I'm also looking at replacing the MiG 15/17/swept wing plane with a scaled down 3 channel version of my big 90mm F-106. I still have a whole spool of LW-ASA filament and I think anything short of a delta wing will not have enough rigidity with how soft and flexible this filament is. This will also be an experiment with vase mode printing since my earlier tests with it show that pretty much any print with retractions results in a print failure.
It should also be very light which should make it an excellent jet trainer, and it should also print well in LW-PLA.
Houndpup Rc
Legendary member
Aw, that's too bad!... Looking great on the designing though!👍
telnar1236
Elite member
The good thing about vase mode designs is that they print very fast, so I have most of the 50mm F-106 fuselage printed already. I did a bit of an experiment with using filler/primer on the nose and it seems to have worked quite effectively at smoothing out the skin.
LW-ASA is a bit of a mixed bag, but it is absurdly light. This plane should only weigh in a bit over 700 g and it is powered by a 50mm 3s EDF but it is almost as big (44" long) as my 80mm super duper sabre design. This design was inspired by a lot of @quorneng 's work and follows a similar philosophy of using a very light large airframe with only the scale inlets. This might also be the first 3D printed plane I've designed that is lighter than an equivalent foam board design.
You pay for this light weight with reduced strength, even compared to LW-PLA. The best comparison is probably a stick and tissue design, although I think the LW-ASA is more flexible, but also a bit tougher. You can just about see on the vertical stabilizer where I accidentally stuck my finger through the skin, but unlike stick and tissue, repairs are much easier as you can just glue the skin back in place - and once it's assembled it is strong enough that it should be fine to fly.
LW-ASA is a bit of a mixed bag, but it is absurdly light. This plane should only weigh in a bit over 700 g and it is powered by a 50mm 3s EDF but it is almost as big (44" long) as my 80mm super duper sabre design. This design was inspired by a lot of @quorneng 's work and follows a similar philosophy of using a very light large airframe with only the scale inlets. This might also be the first 3D printed plane I've designed that is lighter than an equivalent foam board design.
You pay for this light weight with reduced strength, even compared to LW-PLA. The best comparison is probably a stick and tissue design, although I think the LW-ASA is more flexible, but also a bit tougher. You can just about see on the vertical stabilizer where I accidentally stuck my finger through the skin, but unlike stick and tissue, repairs are much easier as you can just glue the skin back in place - and once it's assembled it is strong enough that it should be fine to fly.
telnar1236
Elite member
Got the full fuselage printed and assembled
With all of the parts glued together, I can breathe a bit easier about not accidentally poking a hole in the skin, although it's still somewhat fragile
With all of the parts glued together, I can breathe a bit easier about not accidentally poking a hole in the skin, although it's still somewhat fragile
telnar1236
Elite member
And the F-106 is done and ready to fly! Though the earliest I'll be able to try is this coming Monday and probably it will be later still.
It's extremely light but stronger than I expected. If it works well, I may duplicate it in 4s instead of one of the other builds (I may have been a bit overly ambitious about how many planes I can design in a short time frame). Because of the lack of joints (LW-ASA is FAR too weak to do anything modular), vase mode printing, and roughness of the LW-ASA hiding seams and layer lines, it all blends together more nicely than any of my ABS planes, though I still prefer the bigger version overall.
I also now have the core fuselage of the Ghost 70mm jet printed. It's quite the big plane, which should give it its intended low stall speed. This is definitely built along the same lines as my big 90mm F-106 - a plane significantly bigger than typical for its power system.
Now that I'm a couple months in, I decided to take some stock and look at what I'm now planning for my final designs. Most notably, I found another EDF at the bottom of one of my boxes, so I'm now planning on using that to make the OA-7 and I'm now planning on making the meteor a twin 64mm design. I don't think my remaining 50mm EDF unit would work too well in a fan jet due to the higher weight and the way it performs (this one is from the bad old days of heavy low thrust jets) so I'm back to some kind of higher aspect ratio swept wing fighter (MiG 15 etc.). Green means built and flies well, yellow means built and ready to fly, orange means fully designed but not built, and red means the design is ongoing. No color means I haven't started yet.
It's extremely light but stronger than I expected. If it works well, I may duplicate it in 4s instead of one of the other builds (I may have been a bit overly ambitious about how many planes I can design in a short time frame). Because of the lack of joints (LW-ASA is FAR too weak to do anything modular), vase mode printing, and roughness of the LW-ASA hiding seams and layer lines, it all blends together more nicely than any of my ABS planes, though I still prefer the bigger version overall.
I also now have the core fuselage of the Ghost 70mm jet printed. It's quite the big plane, which should give it its intended low stall speed. This is definitely built along the same lines as my big 90mm F-106 - a plane significantly bigger than typical for its power system.
Now that I'm a couple months in, I decided to take some stock and look at what I'm now planning for my final designs. Most notably, I found another EDF at the bottom of one of my boxes, so I'm now planning on using that to make the OA-7 and I'm now planning on making the meteor a twin 64mm design. I don't think my remaining 50mm EDF unit would work too well in a fan jet due to the higher weight and the way it performs (this one is from the bad old days of heavy low thrust jets) so I'm back to some kind of higher aspect ratio swept wing fighter (MiG 15 etc.). Green means built and flies well, yellow means built and ready to fly, orange means fully designed but not built, and red means the design is ongoing. No color means I haven't started yet.
telnar1236
Elite member
Some early CAD of the MiG 15. You don't realize just how stubby the MiG 15 fuselage is until you start modeling it, but at least that should keep it nice and light.
It's designed at 1/12 scale same as my big F-106, F-104, and Saab 105, and about the right scale to my Super Duper Sabre, Sport Jet, Ghost, and Jet Trainer, if they were real planes. Wingspan is 33" as is the length. I tried to optimize pretty heavily for gentle flight characteristics over anything else so the wings are using the typical Clark Y airfoil and have plenty of washout (4 degrees root to tip). Drag is about 30% higher than the laminar flow wings I've been experimenting with lately, but lift is higher by about the same amount and stall is delayed by almost 10 degrees (the Clark Y starts having significant flow separation around 15 degrees and XFoil stops converging well, but it doesn't really stall till about 20 degrees using full CFD at least with a 250mm chord at 30 m/s since results will vary by Reynolds number).
One nice thing about the MiG 15 is it has plenty of inlet area so I don't need to worry about starving the fan of air. And, the scale bifurcated duct is also perfect for giving space for the battery at RC scales.
I'm thinking of designing this one to use primarily vase mode but with ABS or PLA to try and reduce weight a bit since it will be using a somewhat less powerful EDF unit.
It's designed at 1/12 scale same as my big F-106, F-104, and Saab 105, and about the right scale to my Super Duper Sabre, Sport Jet, Ghost, and Jet Trainer, if they were real planes. Wingspan is 33" as is the length. I tried to optimize pretty heavily for gentle flight characteristics over anything else so the wings are using the typical Clark Y airfoil and have plenty of washout (4 degrees root to tip). Drag is about 30% higher than the laminar flow wings I've been experimenting with lately, but lift is higher by about the same amount and stall is delayed by almost 10 degrees (the Clark Y starts having significant flow separation around 15 degrees and XFoil stops converging well, but it doesn't really stall till about 20 degrees using full CFD at least with a 250mm chord at 30 m/s since results will vary by Reynolds number).
One nice thing about the MiG 15 is it has plenty of inlet area so I don't need to worry about starving the fan of air. And, the scale bifurcated duct is also perfect for giving space for the battery at RC scales.
I'm thinking of designing this one to use primarily vase mode but with ABS or PLA to try and reduce weight a bit since it will be using a somewhat less powerful EDF unit.
telnar1236
Elite member
Got the full fuselage of the Ghost printed now. It's quite the big plane. Current weight is at 1560g with most of it now present, so flying weight should be a bit over 2kg which is pretty similar to my modular jet which used the same power system, although this jet is somewhat bigger with the weight savings mostly coming from the fully ABS structure (vs. fully PLA in the modular jet).
The nose gear is also now designed. Like the main gear it is designed to have the option to install retracts, although I don't plan to at the moment. Back before I got into designing my own planes, I always wondered why the holes for retracts had such odd shapes, and now I know.
While I'm currently building the "light" 4s version of this plane, it's designed to be either 4s or 6s and to have options for complexity and weight. The heavy 6s version should weigh in closer to 2700g with retracts.
The nose gear is also now designed. Like the main gear it is designed to have the option to install retracts, although I don't plan to at the moment. Back before I got into designing my own planes, I always wondered why the holes for retracts had such odd shapes, and now I know.
While I'm currently building the "light" 4s version of this plane, it's designed to be either 4s or 6s and to have options for complexity and weight. The heavy 6s version should weigh in closer to 2700g with retracts.
telnar1236
Elite member
Horizontal stabilizers:
At this point all the modules (nose fuselage, core fuselage, EDF fuselage, tail fuselage, wings, horizontal stabilizer halves, and vertical stabilizer) are present and it's mostly a matter of finishing up the last little bits of design and construction.
At this point all the modules (nose fuselage, core fuselage, EDF fuselage, tail fuselage, wings, horizontal stabilizer halves, and vertical stabilizer) are present and it's mostly a matter of finishing up the last little bits of design and construction.
telnar1236
Elite member
Got in two flights with my 50mm F-106 today with video. As expected, it flies well, like the big 90mm one since it is just that design scaled down. On 3s, it's a bit underpowered, though it still has plenty of power to fly and maneuver very well. I'm guessing the top speed is 60-70 mph on 3s so it's not all that fast, but on the other side of the coin, the very light build means it slows down great and it's a delta which means good high alpha performance is a given. Overall, it's like a smaller, slightly less floaty Viggen and it's probably the easiest to fly of the 3D printed jets I've designed as well as being one of the easier to build. It's not really as much to my personal preference as some of my other designs, since I tend to like heavier faster jets, but that's not a problem with the plane and I didn't build it for me (that's why I have the 90mm version). The slower speed also means that it's more than a dot for a substantial part of the video.
With these flights in hand, I'm definitely also going to use one of the EDFs in a 4s version, and this plane will be posted as a resource in the not-too-distant future since it's ready to go pretty much as is.
Houndpup Rc
Legendary member
Nice! At first a thought it wasn't going to fly, but once it picked up speed it actually flew pretty good!👍
telnar1236
Elite member
Me too - the first flight attempt I didn't trust it to gain speed and let off the throttle which is what resulted in the damage covered by the tape. But it just takes a moment to get on the step on then it's fine
telnar1236
Elite member
Got all the control surfaces installed on the Ghost. It's not a huge change, but it really makes it obvious just how much wing it has (51" wingspan).
I also finally got around to doing the CFD angle of attack sweep which gives me a better idea of top speed and landing speed. The 4s fixed gear version should top out at about 80mph and the 6s version with retracts around 100 mph. Stall speed with flaps down should be around 28 mph on 6s and 25 mph on 4s which is on the lower end for my designs and the lowest out of my big designs (the 50mm F-106 is lower still as should be the MiG 15).
I've also started printing the 50mm MiG 15. Weight should end up around 900 g with the 4s Hyperflow power system and a bit lighter with a more modern EDF.
It should be fairly light and floaty - top speed should be around 70 mph with the fixed gear and 75 mph hand launching. Stall speed, though, should be only 23 mph and landing speed with gear closer to 27 mph so it should be quite easy to handle for an EDF.
You can see the difference between the Clark Y airfoil and less streamlined canopy on the MiG 15 and the laminar flow airfoil and near drag optimal canopy on the Ghost. The flow on the wing becomes turbulent much earlier and the flow separates from the canopy on the MiG 15. However, I could learn something from the contouring around the MiG 15 tail, since the flow seems overall smoother there than on the Ghost.
I also finally got around to doing the CFD angle of attack sweep which gives me a better idea of top speed and landing speed. The 4s fixed gear version should top out at about 80mph and the 6s version with retracts around 100 mph. Stall speed with flaps down should be around 28 mph on 6s and 25 mph on 4s which is on the lower end for my designs and the lowest out of my big designs (the 50mm F-106 is lower still as should be the MiG 15).
I've also started printing the 50mm MiG 15. Weight should end up around 900 g with the 4s Hyperflow power system and a bit lighter with a more modern EDF.
It should be fairly light and floaty - top speed should be around 70 mph with the fixed gear and 75 mph hand launching. Stall speed, though, should be only 23 mph and landing speed with gear closer to 27 mph so it should be quite easy to handle for an EDF.
You can see the difference between the Clark Y airfoil and less streamlined canopy on the MiG 15 and the laminar flow airfoil and near drag optimal canopy on the Ghost. The flow on the wing becomes turbulent much earlier and the flow separates from the canopy on the MiG 15. However, I could learn something from the contouring around the MiG 15 tail, since the flow seems overall smoother there than on the Ghost.
Houndpup Rc
Legendary member
Lookin good! BTW, what program is that?
telnar1236
Elite member
Thanks - Simflow being post processed in Paraview - and Simflow is basically a nice UI for OpenFoam. It's a fairly powerful CFD software, and there's a free version, but there's a bit of a required learning curve and you need some basic theory to understand what you're inputting and getting out
telnar1236
Elite member
Got the canopy printed and the servos installed. At this point, the only things remaining are final wiring and control linkages, the landing gear, and the latch for the canopy.
I'll probably end up reprinting the canopy to deal with some fit issues and a bit of warping, but it's pretty minor so this should do for the maiden flight and testing.
Depending on how much time I have, I may try to maiden this and the BLI flying wing after work sometime this week or this coming weekend, weather and TFRs permitting, but more likely I'll take this week to get everything in good shape and fly it next week.
I'll probably end up reprinting the canopy to deal with some fit issues and a bit of warping, but it's pretty minor so this should do for the maiden flight and testing.
Depending on how much time I have, I may try to maiden this and the BLI flying wing after work sometime this week or this coming weekend, weather and TFRs permitting, but more likely I'll take this week to get everything in good shape and fly it next week.
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