Experimental EDF Jets and Other Ideas

[telnar1236]

EDFs are cool but compared to prop designs they are inefficient and lack thrust. Beyond that, as a whole, the performance of small RC planes has not significantly improved since the switch to lipo batteries and brushless power. Top speeds are still around 120-130 mph unless you want to buy something quite expensive or build a difficult to fly custom design, and flight times have only really gone up from 3 to about 4 minutes on EDFs for most designs and have stayed around 5-10 minutes for most prop planes.

The goal of this thread isn't necessarily to build a plane, but more to experiment with different ideas that might help make better speeds and flight times possible. That said, I still do plan to build a couple planes. Specifically, I have 3 designs I'm thinking of, one which will experiment with increasing speed, one which will experiment with increasing EDF flight times, and one which will try to combine both.

First is the plane I'm currently in the process of working on which is meant to play around with high speeds. It's a pretty conventional pylon racer design, but it's 3D printed and designed to be relatively inexpensive to build. It should also have a reasonable landing speed and easier takeoff performance hopefully than most pylon planes with a power off stall speed of only about 30 mph. Predicting top speed is hard at the best of times, and I don't really know how the power system will be behave, so I'm throwing at a dartboard when I say the top speed should be somewhere around 150 mph.

It's primarily intended to test a laminar flow airfoil I designed for the third plane in this project in a simpler design that I'm less worried about crashing. It uses a 1900 kv motor and a 6x6 prop on 6s.

Next is a design that should increase EDF flight times. I'm mostly building it because I want to experiment with a boundary layer ingesting EDF similar to what I was planning on my original speed plane design, but hopefully in a more forgiving airframe.

This is meant to use a 64mm EDF on 4s with a 4000 mAh battery.

And finally is the plane meant to combine it all into one package. The goal is an EDF with a top speed exceeding 130 mph and capable of flight times over 7 minutes, and hopefully 10 minutes, while still maintaining a 1:1 TWR and that still handles well and is fun to fly. This design will likely change based on the results of testing the first two designs as well as due to any changes in my thinking.

Currently it is designed to use twin 50mm EDFs on 4s, and I would prefer to keep it a 4s plane so that it stays accessible to more people, but I'm also considering an 80mm EDF on 6s. It uses the same laminar flow airfoil as the speed plane in part 1 of this project currently, which should be thick enough to hold retracts while still being efficient enough to give it that high top speed.

As a whole, I expect this project to take me at least half a year if not more, but I'll get a couple of neat designs out of it if they work.

 

[Mr Man]

That pylon racer looks sweet…

 

[telnar1236]

That pylon racer looks sweet…

Thanks, I'm pretty happy about how it's coming along. We'll have to see if it flies though - it's still pretty highly loaded

 

[telnar1236]

The first step in this project is designing and testing a couple of chuck gliders. The pylon racer design is pretty standard and I'm not too worried about my calculated CG being off, but the other two have some potential for interesting and weird characteristics - the flying wing because it's so unconventional, and the jet because it's a T-tail with a large fuselage which can make stalls behave unexpectedly.

Both glide pretty well, which is good. The CG is a bit more forwards than I originally calculated on the twin EDF design which is about what I expected, and is why I built this small glider to test it.

 

[badpilot27]

really cool project with really cool looking planes

also I think you could try making a laminar flow flying wing with a Prandtl bell shaped lift distribution. from what ive seen, prandtl wings have crazy low induced drag coefficients so it might be a good option for a high speed wing that flies under 300mph.

sorry if im bugging you with prandtl d style flying wing requests

 

[telnar1236]

really cool project with really cool looking planes

also I think you could try making a laminar flow flying wing with a Prandtl bell shaped lift distribution. from what ive seen, prandtl wings have crazy low induced drag coefficients so it might be a good option for a high speed wing that flies under 300mph.

sorry if im bugging you with prandtl d style flying wing requests

I don't think a Prandtl style flying wing is really suited to this project. The design is a neat demonstrator for that lift distribution and it's very good at what it's good at, but unfortunately what it's good at is flying very efficiently but slowly and without hard maneuvers or much payload. It isn't really sufficiently stable for a fully aerobatic jet and it isn't really suited to packaging a high power EDF or prop drive motor and battery. The telling statistic is that the Prandtl wing built by NASA had a 25 ft wingspan and only an 18-knot top speed.

It also has all the issues associated with flying wings which is why we don't see it used in full scale aircraft very much despite the fundamental design having been developed in the 1930s. Induced drag is very low, and parasite drag is also quite low, but trim drag is higher and there isn't as much of a moment arm to pitch the aircraft which makes it slower to respond to inputs. In addition, you can't use flaps on a flying wing, and the airfoil is lower lift, so you need more wing area to achieve the same stall speed which mostly negates the reduction in parasite drag.

You also can't use as well optimized of an airfoil as on a more conventional design since the airfoil must provide both the pitching moment and the lift. This essentially forces the flow to transition earlier on the airfoil than on a more conventional wing. In the picture below, you can see the transition from laminar to turbulent flow on my wing. The front is pointing down, and the solid line shows the transition on the top while the dashed line shows the transition on the bottom. It doesn't transition until about the last 20% of the wing.

To get a flying wing airfoil with a similarly low drag coefficient you need to make it somewhat thinner (this is the MH45 airfoil) and even still, the transition occurs earlier on the wing.

And with an airfoil of comparable thickness (the wing root airfoil actually used on the Prandtl-D glider) the transition happens even earlier still.

There may be some room to optimize this, but fundamentally, a flying wing design does not allow for as efficient of an airfoil.

Then finally are the issues associated with this being an RC plane. A high aspect ratio wing is more difficult to store and transport. Also, a tailless design like a Prandtl style wing is hard to maintain orientation on since it has no vertical stabilizer. With a slower plane, this is less of an issue, but with the speeds I'm targeting, it would make things more difficult.

 

[telnar1236]

really cool project with really cool looking planes

also I think you could try making a laminar flow flying wing with a Prandtl bell shaped lift distribution. from what ive seen, prandtl wings have crazy low induced drag coefficients so it might be a good option for a high speed wing that flies under 300mph.

sorry if im bugging you with prandtl d style flying wing requests

Eclipson has their Prandtl style flying wing if you're interested in building one for yourself

3D printed flying wing PRANDTL

This is our printable version of the famous PRANDTL flying wing. This wing is easy to print and build. we provide you all the infomration that you will need to 3D print this RC aircraft. compatible with FPV camera.

www.eclipson-airplanes.com

 

[quorneng]

My own view is that at the sizes of a typical RC plane the benefits of low drag wing sections tend to be swamped by the other losses due to the non linear aerodynamic effects of reduced physical size.
For an electric plane its duration is limited by the power required to fly. If the benefits in aerodynamic efficiency that can be achieved are limited by its size then the only power related characteristic that can be significantly improved is weight reduction.
Models tend to be designed for ease of building and robustness rather than towards the lightest possible structure that just strong enough for the duty required.
This suggest that the actual shape of the wing, or indeed the whole airframe, is of less importance that the weight of the structure required to achieve it. I note it is not that unusual in full size for a plane to carry a fuel load equivalent to 50% of its take off weight.
How many electric RC planes actually achieve this sort of figure in battery weight despite the improvement in structural strength to weight that reduced physical dimensions give.
Applying full size detailed stress analysis is not likely realistic for the model fraternity however a small diameter carbon tube spar in a foam wing may be simple to do and gives "adequate" strength does it give the best possible strength to weight ratio?
I do believe more effort into the "how, what & where" materials are used in a plane's construction can give greater benefits than can ever be achieved by aerodynamic improvements.

As an example I have a small home built true scale EDF which has a battery that is 38% of its flying weight. This coupled with running its EDF at its most efficient power level in terms of thrust/Watt as well as making full use of the structural benefits of reduced size mean it can fly for 12 minutes. The down side is it is not the fastest EDF in the world.

 

[L Edge]

Wow!!! That is an agenda you have. Since there are only a few that fly EDF's, it is nifty that experiments are being done to find out what happens and share with others. EDF design has many aspects that need to be looked at to achieve what you want. It is a game of what you want/what happens. Especially inlet/outlet of EDF/s in plane that will ruin your thrust.

For instance, for your pylon plane to increase speed, I would change to E-Flite Electrofite's shape wing and modify the back end to a V-tail so drag is reduced. Q-500 racers now fly a V-Tail rather than elevator/rudder and the max speed went from 135 to 150. Maybe??

For your increase in flight time of EDF's, I accomplished it like quorneng did. I have a 5 blade 64mm EDF mounted on a flying wing with no vertical stabs and a my designed "stabilizer" with a 1300 mah battery. Flies for over 10 min with battery filled to only 95 %.

Until a better battery is designed, doubt that you can combine high speed and long flights(7-10 min). Love to have you prove me wrong.

Like your approach where you put the EDF downstream of wing. Drag of plane is always lower when engine/s are aft of main wing. Especially having lots of weight in rear that will need balancing.

My project:
Came to the conclusion that planes like the B-2 Spirit will definitely will need drag rudders and most likely a gyro to to solve roll/yaw. Hoping to use elevons without a gyro.

 

[telnar1236]

My own view is that at the sizes of a typical RC plane the benefits of low drag wing sections tend to be swamped by the other losses due to the non linear aerodynamic effects of reduced physical size.
For an electric plane its duration is limited by the power required to fly. If the benefits in aerodynamic efficiency that can be achieved are limited by its size then the only power related characteristic that can be significantly improved is weight reduction.
Models tend to be designed for ease of building and robustness rather than towards the lightest possible structure that just strong enough for the duty required.
This suggest that the actual shape of the wing, or indeed the whole airframe, is of less importance that the weight of the structure required to achieve it. I note it is not that unusual in full size for a plane to carry a fuel load equivalent to 50% of its take off weight.
How many electric RC planes actually achieve this sort of figure in battery weight despite the improvement in structural strength to weight that reduced physical dimensions give.
Applying full size detailed stress analysis is not likely realistic for the model fraternity however a small diameter carbon tube spar in a foam wing may be simple to do and gives "adequate" strength does it give the best possible strength to weight ratio?
I do believe more effort into the "how, what & where" materials are used in a plane's construction can give greater benefits than can ever be achieved by aerodynamic improvements.

As an example I have a small home built true scale EDF which has a battery that is 38% of its flying weight. This coupled with running its EDF at its most efficient power level in terms of thrust/Watt as well as making full use of the structural benefits of reduced size mean it can fly for 12 minutes. The down side is it is not the fastest EDF in the world.

In general, I agree, with the caveat that this is most true for foam planes. With foam planes, it takes a ton of effort to cut drag, and realistically you can only go so far, but with 3D printed planes you have much greater control over your geometry so you can do more to reduce drag.

Part of why I think my goals are achievable is the excellent thrust to weight ratio of some of the newer EDFs. To get that high percentage of the weight as a battery you can go lighter, or you can just add more batteries to a heavier airframe with the corresponding penalty in required power and stall speed. The goal is for this 35" wingspan airframe to weigh in at around 2kg which should keep the stall speed acceptable for a takeoff and landing from a paved runway but for it to carry around 800g worth of batteries in the form of 2 4000 mAh packs in parallel. This leaves me 1200g for the rest of my airframe which should be pretty doable even with 3D printing - my similar sized single 50mm jet trainer has a flying weight of only 1100g including the battery, so even with the extra servos, EDF and retracts, I think I can keep the weight inside those limits. So the goal is a similar 40% of the weight in batteries, just achieved a bit differently.

Where I couldn't disagree more is with the assertion that there are limited gains to be had from aerodynamics. Aerodynamics are certainly different at low speeds and small scales, but all the analysis I run is at the correct Reynolds number and aerodynamics are still very important.

I think a lot of the drag we get on rc planes is self-inflicted. Part of what led to this project was an attempt to assess the characteristics of standard foam wings and the corresponding characteristics. That led to the realization that they are way draggier than I ever thought. As an example, I think basically everyone has used a flat plate foam wing at some point. Given that it's only 6mm thick, I always assumed it wasn't going to add that much drag, but I was wrong. At a chord length of 10", the airfoil I'm using on the pylon racer has a bit over half the drag of a flat plate foam wing, and by the time you get down to 3" as at a wing tip it's a fair bit less than half as much drag. Even adding bevels to the foam board wing, you're still looking at about the same drag as the laminar flow airfoil at the wing root, and around twice as much drag as the laminar flow airfoil towards the wingtip, despite the laminar flow airfoil being about 5 times thicker at the root and around twice as thick at the tip. Of course, the fuselage also adds drag, but it should be possible to cut the drag substantially there too, if not by quite as much. This is a plot of the turbulent kinetic energy for a flat plate wing without bevels vs. a laminar flow airfoil - the difference is night and day - both 10" chord at 150 mph. I capped the plot scale the same for both so you can see the turbulent boundary layer more clearly.

The rule is that your thrust to weight ratio needs to be greater than the ratio of drag to lift to maintain flight, so as you said, you can cut weight, which means you need less thrust, but decreasing drag also works and gives you the benefit of higher top speeds as well.

Ultimately though, the proof will need to be in the pudding, I don't know for sure that any of this will work once it gets off my computer and into the real world. I think the on paper numbers add up, but we'll have to see.

 

[telnar1236]

Wow!!! That is an agenda you have. Since there are only a few that fly EDF's, it is nifty that experiments are being done to find out what happens and share with others. EDF design has many aspects that need to be looked at to achieve what you want. It is a game of what you want/what happens. Especially inlet/outlet of EDF/s in plane that will ruin your thrust.

For instance, for your pylon plane to increase speed, I would change to E-Flite Electrofite's shape wing and modify the back end to a V-tail so drag is reduced. Q-500 racers now fly a V-Tail rather than elevator/rudder and the max speed went from 135 to 150. Maybe??

For your increase in flight time of EDF's, I accomplished it like quorneng did. I have a 5 blade 64mm EDF mounted on a flying wing with no vertical stabs and a my designed "stabilizer" with a 1300 mah battery. Flies for over 10 min with battery filled to only 95 %.

Until a better battery is designed, doubt that you can combine high speed and long flights(7-10 min). Love to have you prove me wrong.

Like your approach where you put the EDF downstream of wing. Drag of plane is always lower when engine/s are aft of main wing. Especially having lots of weight in rear that will need balancing.

My project:
Came to the conclusion that planes like the B-2 Spirit will definitely will need drag rudders and most likely a gyro to to solve roll/yaw. Hoping to use elevons without a gyro.

Yeah, it's definitely going to be quite the challenge that I've set for myself here.

I think the technology is just about there now though it's certainly on the edge of what's possible. The Flyfans L-39 is a 100-mph plane capable of 10-minute flight times and is pretty fun to fly despite that. This thread could also be called that plane has really awful landing gear so I went way overboard and decided to design a whole new airframe to do the same thing slightly better.

I definitely agree that EDF inlet/nozzle design is a major area to look into. I'm thinking about investigating variable geometry EDF inlets that would give more control over the angle of attack of the EDF blades at a wide range of airspeeds - which seems simpler than designing a variable pitch prop instead - but I don't think I can quite get it working small enough for a 50mm EDF and so it's sort of a last resort if I end up switching to an 80mm fan, or if after this project wraps up I still want to go even crazier.

Yeah, the pylon plane isn't as well optimized as physically possible. The goal is to test a similar wing and tail design to the final jet, so the wing shape isn't perfect. I'm not sure the electrostreak wing is too well optimized either, but I haven't really looked too much at that design

 

[telnar1236]

The beginnings of the pylon racer. It's a pretty simple design and fairly small so it's only required four print jobs to make so far and has come together almost shockingly fast.

I'm using infill on the wing since it gives a smoother skin than what can be achieved with a vase mode print or my generally preferred method of a modeled internal structure. Otherwise, otherwise it's a pretty conventional 3D printed airframe.
The big challenge will be figuring out how to print the spinner. It will be spinning at almost 49,000 RPM which means it will really want to fly apart. I certainly will be in a different room the first couple times I bring it up to speed since if it does fail it will launch bits of itself at around 145 mph which I'd rather not get hit by. Most likely, I will use nylon or carbon fiber nylon to try and make sure it stands up to the kinds of speeds it will need to

 

[Mr Man]

The beginnings of the pylon racer. It's a pretty simple design and fairly small so it's only required four print jobs to make so far and has come together almost shockingly fast.
View attachment 253693
I'm using infill on the wing since it gives a smoother skin than what can be achieved with a vase mode print or my generally preferred method of a modeled internal structure. Otherwise, otherwise it's a pretty conventional 3D printed airframe.
The big challenge will be figuring out how to print the spinner. It will be spinning at almost 49,000 RPM which means it will really want to fly apart. I certainly will be in a different room the first couple times I bring it up to speed since if it does fail it will launch bits of itself at around 145 mph which I'd rather not get hit by. Most likely, I will use nylon or carbon fiber nylon to try and make sure it stands up to the kinds of speeds it will need to

Dubro also makes spinners. 👍

 

[DuncanM23]

This might be utterly unrealistic, but have you done the energy maths backwards?
In theory, you could start with the amount of energy available in a charged battery, distribute it across the length of time you want to fly for, and that gives your power consumption, which gives your drag figure to aim at. Then you can tweak your drag math until you hit that number?

 

[telnar1236]

Dubro also makes spinners. 👍

But that would be making my life too simple. More seriously, if I ever do release this design, I'll probably redesign the nose to use an off the shelf spinner so that people don't need to try and mess with such difficult printing. However, for my plane, printing my own lets me perfectly match the curvature of the spinner to the airframe and pretty much get exactly the design I want. It also cost around 30 cents worth of filament, and I can now make as many as I want and only have to wait less than an hour to have one ready to go.

It was actually a bit shockingly easy to make though one and it worked on my first try. I used carbon fiber nylon (Fiberon PA612-CF15 since I figure the print will absorb moisture over time and I need it to remain strong more so than be very strong to start off with) and a 0.6mm nozzle. I then did my best to balance it on my bead lathe and stuck it on the plane and spun up the motor. And it didn't explode, and it wasn't even really out of balance. If the weather permits, I may even get to try and fly it this weekend.

 

[telnar1236]

This might be utterly unrealistic, but have you done the energy maths backwards?
In theory, you could start with the amount of energy available in a charged battery, distribute it across the length of time you want to fly for, and that gives your power consumption, which gives your drag figure to aim at. Then you can tweak your drag math until you hit that number?

It would be pretty difficult to do. There are two main reasons. One is that I don't really know how the power system will behave except for at 0% and 100% throttle and 0 airspeed, and the time, effort, and annoyance to my neighbors as I spend hours running a loud EDF aren't really worth it. The other is that while if I did have a good sense of power system performance, I could give a very precise value for the acceptable drag, it would be somewhat hard to convert that into changes to the geometry of the plane - there isn't a simple formula for how the drag changes with the geometry and I need to simulate the airframe in a given condition to see how it will behave in that condition.
That said, you can at least do a plausibility check for speed and flight time based on power. In the case of my pylon racer, CFD predicts a drag of 12.4 N at 180 mph (82 m/s). The power system pulls 40 A at 25.2 V when static which is going to be the max power it can give and therefore provide an upper bound - in flight the prop will be less highly loaded and the power system will draw less current. Power can be given by current times voltage (25.2 V*40 A = 1,008 W) and by speed times drag (12.4 N * 82 m/s = 1,016 W). However, the power system is not 100% efficient, so assuming the motor/battery combination is 90% efficient and the prop is 80% efficient, the available power is only 726 W which is less than that required to hit 180 mph. However, the power required falls with the cube of the speed. 10 m/s slower, the drag is only 9.5 N so the total power is only 72 m/s * 9.5 N = 684 W which is within the realm of plausibility. That said, as the airspeed increases, the current draw will decrease, so the top speed should be somewhere slower than the max calculated with this approach. This is where quantifying the performance of the power at system at speed is needed - as the prop unloads it will spin faster which means the power doesn't decrease linearly between standing still and the pitch speed and the effort required to do that isn't really worth it.

 

[Houndpup Rc]

It would be pretty difficult to do. There are two main reasons. One is that I don't really know how the power system will behave except for at 0% and 100% throttle and 0 airspeed, and the time, effort, and annoyance to my neighbors as I spend hours running a loud EDF aren't really worth it. The other is that while if I did have a good sense of power system performance, I could give a very precise value for the acceptable drag, it would be somewhat hard to convert that into changes to the geometry of the plane - there isn't a simple formula for how the drag changes with the geometry and I need to simulate the airframe in a given condition to see how it will behave in that condition.
That said, you can at least do a plausibility check for speed and flight time based on power. In the case of my pylon racer, CFD predicts a drag of 12.4 N at 180 mph (82 m/s). The power system pulls 40 A at 25.2 V when static which is going to be the max power it can give and therefore provide an upper bound - in flight the prop will be less highly loaded and the power system will draw less current. Power can be given by current times voltage (25.2 V*40 A = 1,008 W) and by speed times drag (12.4 N * 82 m/s = 1,016 W). However, the power system is not 100% efficient, so assuming the motor/battery combination is 90% efficient and the prop is 80% efficient, the available power is only 726 W which is less than that required to hit 180 mph. However, the power required falls with the cube of the speed. 10 m/s slower, the drag is only 9.5 N so the total power is only 72 m/s * 9.5 N = 684 W which is within the realm of plausibility. That said, as the airspeed increases, the current draw will decrease, so the top speed should be somewhere slower than the max calculated with this approach. This is where quantifying the performance of the power at system at speed is needed - as the prop unloads it will spin faster which means the power doesn't decrease linearly between standing still and the pitch speed and the effort required to do that isn't really worth it.

Wow! Talk about tech! JK 👍 😂

 

[Houndpup Rc]

It would be pretty difficult to do. There are two main reasons. One is that I don't really know how the power system will behave except for at 0% and 100% throttle and 0 airspeed, and the time, effort, and annoyance to my neighbors as I spend hours running a loud EDF aren't really worth it. The other is that while if I did have a good sense of power system performance, I could give a very precise value for the acceptable drag, it would be somewhat hard to convert that into changes to the geometry of the plane - there isn't a simple formula for how the drag changes with the geometry and I need to simulate the airframe in a given condition to see how it will behave in that condition.
That said, you can at least do a plausibility check for speed and flight time based on power. In the case of my pylon racer, CFD predicts a drag of 12.4 N at 180 mph (82 m/s). The power system pulls 40 A at 25.2 V when static which is going to be the max power it can give and therefore provide an upper bound - in flight the prop will be less highly loaded and the power system will draw less current. Power can be given by current times voltage (25.2 V*40 A = 1,008 W) and by speed times drag (12.4 N * 82 m/s = 1,016 W). However, the power system is not 100% efficient, so assuming the motor/battery combination is 90% efficient and the prop is 80% efficient, the available power is only 726 W which is less than that required to hit 180 mph. However, the power required falls with the cube of the speed. 10 m/s slower, the drag is only 9.5 N so the total power is only 72 m/s * 9.5 N = 684 W which is within the realm of plausibility. That said, as the airspeed increases, the current draw will decrease, so the top speed should be somewhere slower than the max calculated with this approach. This is where quantifying the performance of the power at system at speed is needed - as the prop unloads it will spin faster which means the power doesn't decrease linearly between standing still and the pitch speed and the effort required to do that isn't really worth it.

Very interesting!👍

 

[telnar1236]

I tried flying the pylon plane today, and it was a mixed bag. The aerodynamics seem to be very good and the stall actually seems to be gentler than I was predicting from CFD. The launch dolly method for takeoff I'm using also worked better than I expected. The plane sits on a removable dolly with a peg to hold it in place near the CG and then as it takes off it leaves the dolly behind. I was worried about it sticking and not falling away properly, but that didn't end up being an issue.

However, the structure isn't strong enough. It managed to rip one of its wings off a bit into the first flight. I didn't carry the GPS module, so I don't know how fast it was going, but people standing with me were guessing upwards of 80 mph ground speed into a 15 mph headwind, which would be a 95 mph airspeed, and I was at about half throttle and on 4s since I only have one 6s pack of the right size which I wanted to save for the speed run. Therefore, I think it should end up being quite fast.

For the next version, there will be a 10mm carbon fiber spar running into the wing which should avoid the issues with the wings falling off, and I won't use silk PLA since while I thought the silver looked cool, it is weaker, and the failure was not at the wing root, but actually in the silk PLA fuselage skin.

 

[Mr Man]

I tried flying the pylon plane today, and it was a mixed bag. The aerodynamics seem to be very good and the stall actually seems to be gentler than I was predicting from CFD. The launch dolly method for takeoff I'm using also worked better than I expected. The plane sits on a removable dolly with a peg to hold it in place near the CG and then as it takes off it leaves the dolly behind. I was worried about it sticking and not falling away properly, but that didn't end up being an issue.
View attachment 253740
However, the structure isn't strong enough. It managed to rip one of its wings off a bit into the first flight. I didn't carry the GPS module, so I don't know how fast it was going, but people standing with me were guessing upwards of 80 mph ground speed into a 15 mph headwind, which would be a 95 mph airspeed, and I was at about half throttle and on 4s since I only have one 6s pack of the right size which I wanted to save for the speed run. Therefore, I think it should end up being quite fast.

For the next version, there will be a 10mm carbon fiber spar running into the wing which should avoid the issues with the wings falling off, and I won't use silk PLA since while I thought the silver looked cool, it is weaker, and the failure was not at the wing root, but actually in the silk PLA fuselage skin.

Yeah, I’ve used silk pla before, and it is weaker than normal gloss pla.