telnar1236
Elite member
Didn't know this was in RealFlight - I'll have to check it outI have flown the living snot out of this plane in RealFlight!
LB
Didn't know this was in RealFlight - I'll have to check it outI have flown the living snot out of this plane in RealFlight!
LB
what software do u useTurns out I'm just bad at designing wing apex fences. I reread the NASA paper and realized I'd missed a couple things about the geometry. The redesigned wing fence creates a 16% boost in lift which is closer to what I was looking for (the equivalent of cutting 360 grams out of the weight in terms of landing speed). It also reduces the pitching moment by 36% which will reduce the needed deflection of the elevons and result in an even greater increase in lift. Paired with weight reductions and the increased drag from the wing fence I think this design will make the plane much easier to handle. I'll still include the current wing design with the final STLs for people with 500' runways since it will bleed less speed in turns and handles very nicely once in the air, but for most people I think the wing with the retractable fence will work better.
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You can see how much better developed the vortex is with this new design and how the flow stays attached for most of the length of the wing as opposed to just closer to leading edge as on the previous designs.
u can try dog teeth aka leading edge extensions https://en.wikipedia.org/wiki/Leading-edge_extensionI don't think I'm going to manage to reduce the landing speed as much as I want just based on reducing the weight, so I've been looking into ways to improve the aerodynamics. Delta wings aren't really compatible with conventional flaps since they would just make the plane pitch down so I need another option.
One possibility is to put a set of split flaps in the middle of the wing where they won't cause much pitch change.
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The issue with this kind of flap design is that they don't actually do that much. Wings fly primarily due to the low pressure on top of them and the low pressure on top of the flaps is shared with the bottom surface of the wing. Therefore, they are mostly air brakes, only boosting lift by about 5% and slightly making the plane want to nose up decreasing the loss of lift due to trim forces on the elevons. They may be worth adding still since every little bit helps, though, especially if combined with reduced weight and other high lift devices.
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I did some reading and also stumbled on a second possibility. Wing apex fences look very strange, but like flaps they increase the lift at a given angle of attack.
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Since the wing has enough lift to fly slower, just while at a higher angle of attack than the plane lands at, the apex fence could be a good option and easier to design and more effective than the flaps. It works by generating and capturing a vortex similar to what delta wing generates at higher angles of attack which increases the lift at the cost of drag. Here's a paper from NASA describing how they work: https://ntrs.nasa.gov/api/citations/19940019630/downloads/19940019630.pdf
Here is some CFD showing it a little more clearly. The wing with no fence doesn't generate much of a leading-edge vortex at all at 12.5 degrees AOA.
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Adding in a small partial fence creates a vortex over the inboard part of the wing and boosts lift by about 5%.
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And adding in a fence over most of the span generates a much larger and stronger vortex and boosts lift by about 10%.
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The NASA paper shows that the lift increase should be able to be much bigger (about 20%) at least at the Reynolds numbers they tested, so I'm still trying to refine my designs. I'm trying to keep them relatively low profile to reduce how much of the wing the mechanism to deploy and retract them would take, but I think I should be able to improve performance by increasing the height and angle of the fence closer to 5 degrees or possibly by splitting the fence into a couple smaller ones. Tilting it back by 10 degrees should also help a tiny bit. In the last CFD of the full fence, the outer section of the fence doesn't actually generate much of a vortex, probably due to its smaller angle. I was trying to replicate a gothic wing fence with a smaller outboard angle (amazing name on the part of whoever designed it) that should get better performance, but that may not work the same on this particular plane. It's also possible that wing apex fences just work much better on full scale planes or I did a bad job designing it.
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(From the NASA paper I found)
For the analysis shown above, the free version of Simflow to run the analysis and Paraview to generate the plots. It's a bit of a learning curve to use, but for wings that generate things like vortices it's the only way to get particularly accurate results.what software do u use
what software do u use
Those mostly improve the high angle of attack characteristics of a wing but don't do much to boost lift at lower angles of attack. As a delta wing, this wing can already reach 40 degrees AOA and get plenty of lift to slow down, but the issue is that the plane cannot land at those angles of attack because the tail would hit before the landing gear. So what I'm looking for is a way to shift the lift curve to the left so that it generates more lift at lower angles of attack. Basically flaps on a delta wing. That's what the wing apex fence does very effectively. This is an incomplete plot from an earlier iteration of the wing fence that shows what I'm trying to do.u can try dog teeth aka leading edge extensions https://en.wikipedia.org/wiki/Leading-edge_extension
If only, I wish I could do thatWhat, you mean you can't do this?
If only, I wish I could do that
Yeah, if you do my a+b approach, you could come close. Want to hear it? Guaranteed less than 150 ft for landing. And that includes acrobatics including the "Cobra" if you can practice enough.If only, I wish I could do that
The issue isn't so much that the plane can't perform that maneuver as the height of the landing gear and how brittle 3D printed structures are. I can't land at more than 14.5 degrees AOA and I can't come it at a higher AOA and then drop the nose and let it "plop" down since it would breakWhat, you mean you can't do this?
Yeah, if you do my a+b approach, you could come close. Want to hear it? Guaranteed less than 150 ft for landing. And that includes acrobatics including the "Cobra" if you can practice enough.
The issue isn't so much that the plane can't perform that maneuver as the height of the landing gear and how brittle 3D printed structures are. I can't land at more than 14.5 degrees AOA and I can't come it at a higher AOA and then drop the nose and let it "plop" down since it would break
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mFor the analysis shown above, the free version of Simflow to run the analysis and Paraview to generate the plots. It's a bit of a learning curve to use, but for wings that generate things like vortices it's the only way to get particularly accurate results.
Those mostly improve the high angle of attack characteristics of a wing but don't do much to boost lift at lower angles of attack. As a delta wing, this wing can already reach 40 degrees AOA and get plenty of lift to slow down, but the issue is that the plane cannot land at those angles of attack because the tail would hit before the landing gear. So what I'm looking for is a way to shift the lift curve to the left so that it generates more lift at lower angles of attack. Basically flaps on a delta wing. That's what the wing apex fence does very effectively. This is an incomplete plot from an earlier iteration of the wing fence that shows what I'm trying to do.
View attachment 246949
this is a nice thing to think of a solution to during history classFor the analysis shown above, the free version of Simflow to run the analysis and Paraview to generate the plots. It's a bit of a learning curve to use, but for wings that generate things like vortices it's the only way to get particularly accurate results.
Those mostly improve the high angle of attack characteristics of a wing but don't do much to boost lift at lower angles of attack. As a delta wing, this wing can already reach 40 degrees AOA and get plenty of lift to slow down, but the issue is that the plane cannot land at those angles of attack because the tail would hit before the landing gear. So what I'm looking for is a way to shift the lift curve to the left so that it generates more lift at lower angles of attack. Basically flaps on a delta wing. That's what the wing apex fence does very effectively. This is an incomplete plot from an earlier iteration of the wing fence that shows what I'm trying to do.
View attachment 246949
Honestly those would probably help a lot. Convair did actually propose variants of the F-106 with canards, so it's not that out there either.what abt canrds hmmmmmmmmmmm
No problem. It's a bit of a learning curve, but definitely worth it. The risk of CFD is garbage in, garbage out, so if an answer doesn't seem to make sense or the mesh doesn't represent the real geometry, it's probably a safe bet that the answer it gives will be wrong.thx for the simflow suggestion been searching for something
m
tru thats why the hmmmmmmmmmmmmmmmmmmmmmmmmmmmmmHonestly those would probably help a lot. Convair did actually propose variants of the F-106 with canards, so it's not that out there either.
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I'm just not a fan of the way they look even if they would help a lot aerodynamically. I thought about retractable canards, similar in concept to the glove vanes on an F-14, but by the time they were small enough to fully retract, they wouldn't help that much with lift either. It ultimately comes down to the v1 being the right size for a 4s plane and not a 6s plane which means it's too heavy for its wing without major aerodynamic modifications which would mean it wasn't an F-106A anymore.
He's definitely a good pilot and that's a beautiful model. Can't tell if he was just trying to fly it gentle and scale, but it looked a bit underpower. The Dan Savage plans seem to be a pretty common starting place. I used them as a reference when building my 70mm version and to confirm the CG. I think the wing on the F-106 just isn't very good at producing lift at lower angles of attack which makes the landings a pain.Wow, decided that the F-106 is a bird that you pretty well defined and is meant for a good pilot. If you go to "you tube" and review the EDF's and turbine F-106 bird's, the takeoffs and landings require a good feel for the bird and really "eat up the runway".
Found one video that had a short t/o and landing that was relaxing. Picked this one since he had a 80 edf and he mentioned that he recommends a rudder for easier landings. The guy that flys it is a top heli pilot as well as excellent pilot, so you can see.
Have you ever thought of changing the delta angle to give you more area?