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Anyone build for high altitude

whackflyer

Well-known member
#2
I know high altitude isn't a clear term but let just above 15000 feet, anyone build a plane specifically to for high altitude flying?
People probably have attempted, but it's extremely illegal, and very hard to accomplish with the electronics available to us. Us as hobbyists aren't supposed to fly over 400 feet. There would be serious consequences if you got caught. At a time such as now you don't want to get caught by the FAA, they're pretty much campaigning against the hobby as a whole, trying to make way for the "delivery drones" 🙄. It would be cool to fly that high tho!
 
#3
Yeap the 400 feet law is a bit of a pain for fpv even my simple nitro trainer get above that altitude in no time. I mainly asked for 2 reasons I seen a couple of fpv video on youtube showing people fly standard prebuild rc airplane to get close to 30000 feet and curiosity of how would someone even start if they were to build a plane from scratch, I have build planes from kit before but not from scratch yet and figure designing something cool like a plane for a specific altitude would be a fun thought experiment and the knowledge can be applied to my everyday planes as i would like at some point to build my own gliders
 

"Corpse"

Well-known member
#4
Yeap the 400 feet law is a bit of a pain for fpv even my simple nitro trainer get above that altitude in no time. I mainly asked for 2 reasons I seen a couple of fpv video on youtube showing people fly standard prebuild rc airplane to get close to 30000 feet and curiosity of how would someone even start if they were to build a plane from scratch, I have build planes from kit before but not from scratch yet and figure designing something cool like a plane for a specific altitude would be a fun thought experiment and the knowledge can be applied to my everyday planes as i would like at some point to build my own gliders
I know you can get clearance in some cases, especially if you live around class G or D airspace. It is possible, but frustrating to get all the legal stuff done.
 

"Corpse"

Well-known member
#6
Really? you can get clearance? well heck that is news for me I get nervous just going to 1000 feet on trainer and that is unintentional
I know you can do a lot of silly crap if you let your Flight control tower and the FAA know, and you get their permission. It doesn't hurt to ask!
 

Ketchup

4s mini mustang
#7
So first off, I don’t think that a standard prebuilt plane can reach those altitudes. First of all, they would have range issues, and you would need to modify some stuff to overcome that. Secondly, they probably wouldn’t be able to create enough lift at those altitudes. Finally, this might not be as bad, but it can get cold up there. A quick search says that it can get well below freezing at 10,000 feet. At those temperatures a normal lipo would have issues delivering enough current, and some stuff on the plane might just freeze up. So yeah, not with a standard bnf plane or something. To do this though, you would need a plane with high lift, so possibly a glider design. Also, you would need a decent amount of power from a large motor with a large prop. To address the cold issue, you could use heating elements around the plane. Finally, for the range issue, you can try using a lower frequency tx and rx (maybe 72 mhz) and broadcast a very powerful signal (you might need a ham radio license to do this). There would definitely be some other issues, but that is all I could think of now. Also, I hope that you aren’t thinking of doing this, since the hobby is already under attack and this wouldn’t help. You did say that you thought it would be a fun thought experiment though, ad you were definitely right!
edit: I wasn’t sure if you could get clearance for this or not, but apparently you can. It would be really fun to see this happen.
 

"Corpse"

Well-known member
#8
So first off, I don’t think that a standard prebuilt plane can reach those altitudes. First of all, they would have range issues, and you would need to modify some stuff to overcome that. Secondly, they probably wouldn’t be able to create enough lift at those altitudes. Finally, this might not be as bad, but it can get cold up there. A quick search says that it can get well below freezing at 10,000 feet. At those temperatures a normal lipo would have issues delivering enough current, and some stuff on the plane might just freeze up. So yeah, not with a standard bnf plane or something. To do this though, you would need a plane with high lift, so possibly a glider design. Also, you would need a decent amount of power from a large motor with a large prop. To address the cold issue, you could use heating elements around the plane. Finally, for the range issue, you can try using a lower frequency tx and rx (maybe 72 mhz) and broadcast a very powerful signal (you might need a ham radio license to do this). There would definitely be some other issues, but that is all I could think of now. Also, I hope that you aren’t thinking of doing this, since the hobby is already under attack and this wouldn’t help. You did say that you thought it would be a fun thought experiment though, ad you were definitely right!
edit: I wasn’t sure if you could get clearance for this or not, but apparently you can. It would be really fun to see this happen.
I know David Windestal flew a little delta wing into the edge of space, but he used a weather balloon so that stops the need for heating elements. He used a really high power FPV VTX and a really nice receiver. That is probably the best way to get altitude, but not the best way to keep it controlled. You could drift for miles and lose your plane.:cry:
 
#9
By prebuild I am referring to the airframe as it is not scratch build and not optimized for the altitude. Below are some of the videos I am referring to. There really isn't much that is custom. As for the cold issue a lot of the electronics in RC airplanes like ESC and motor can create quite a bit of heat in enclosed body to keep them warm. Heck, even lipo as they get drained create a bit of heat.



 

Ketchup

4s mini mustang
#10
I know David Windestal flew a little delta wing into the edge of space, but he used a weather balloon so that stops the need for heating elements. He used a really high power FPV VTX and a really nice receiver. That is probably the best way to get altitude, but not the best way to keep it controlled. You could drift for miles and lose your plane.:cry:
Yep, I think that he almost lost his plane in that video. It was cool though!
 

Ketchup

4s mini mustang
#11
By prebuild I am referring to the airframe as it is not scratch build and not optimized for the altitude. Below are some of the videos I am referring to. There really isn't much that is custom. As for the cold issue a lot of the electronics in RC airplanes like ESC and motor can create quite a bit of heat in enclosed body to keep them warm. Heck, even lipo as they get drained create a bit of heat.
Yes, electronics do create some heat, but even with that there will be less power and flight time. In an FT video that they were doing with helis, I remember that josh had issues with the cold and it’s effect on lipos. The issue might not be as bad with high altitude flights instead of just going out in the cold though. Also, when you said prebuilt plane I instantly thought of a horizon cub or something, I never thought of planes like the mini talon that was apparently used in one of the videos. It would definitely be much easier with something like that.
 
#12
I can see the heli having a problem with the cold as the electronics are open to the elements and allow to radiate the heat out. Airplanes on the other hand can sometimes struggle with to much heat, I know some of my friends have actually had trouble with their video tx getting too hot and having to mount it externally. So in a higher attitude that may actually help. I have to say if someone can get a horizon cub to those altitude give that person a prize
 

quorneng

Well-known member
#13
Apart from any legal issues the simple rule for high altitude flight is to keep the wing loading low or the velocity high. This is why helicopters struggle at altitude. Their blade tips are mach limited and their blade loading is high compared to planes.
The advantage of electric apart from the effect of cold on a LiPo is, unlike IC, the power does not fall away with the drop in atmospheric pressure. For electric the altitude limit is thus when the pressure indicated air speed approaches the aerodynamic stall speed.
This is why an electric 'spy' plane can cruise at 100,000 ft whereas air breathing IC are unable to generate the power to fly at such an altitude.
 

Piotrsko

Well-known member
#14
Comments: it's 400 ft agl. If you are standing on the trailhead at mt whitney, thats 14,505+ 400 agl, and there might be a class F airspace exclusion. Above 15000, stall airspeed starts approaching the max speed models fly at so you need something that flies faster than say 100 mph. Above 100 flutter becomes a HUGE issue, as well as just being able to fly it. Go read the stuff Major Payne (appropriate legal name) had to do to break the altitude and glider speed records couple years ago. I'm not saying dont do it, just starting a discussion on how hard it is going to be.
 
#15
I can't find a major Payne but did find Jim payne that is part of the Perlan Project. Which is a full-scale aircraft the complexity for a full-scale craft that has humans inside of it are vastly more complex than a UAV or RC airplane. It is impressive the altitude they got with a glider. I know it is a balancing act between low wing loading and speed but was hoping for maybe a book or an article that goes into more detail about it. The talon, for example, was flying at around 63mph
 

IcedStorm777

Well-known member
#17
I will say that the aerodynamics would be very different to. I live at 7500ft (Colorado) and when I brought my planes down to Texas for FliteFest they all were able to fly much slower and longer on the same battery. So you would probably have to build a "high altitude" airfoil for an RC plane at that height. Just my two cents.
 
#18
That was most likely airspeed. The ground speed would have been much higher than 63 mph.
I would not say by much the airframe itself cant handle high speed best I have seen was around 100mph on another forum. But typical speed for it is between 40 to 70mph
I will say that the aerodynamics would be very different to. I live at 7500ft (Colorado) and when I brought my planes down to Texas for FliteFest they all were able to fly much slower and longer on the same battery. So you would probably have to build a "high altitude" airfoil for an RC plane at that height. Just my two cents.
of course, a specific airfoil for a given altitude would be better that is why I originally asked my question.
 

Ketchup

4s mini mustang
#19
I would not say by much the airframe itself cant handle high speed best I have seen was around 100mph on another forum. But typical speed for it is between 40 to 70mph
Again, this is airspeed. The airframe might not be able to handle over 70 mph, but that is airspeed. The airspeed can stay the same, but to do that the ground speed must change when increasing altitude.
 
#20
I was simply adding more details about the airframe in question as some don't seem to know the spec of it. As for the ground speed I was just pointing out that your statement below of ground speed having to be strictly higher is wrong it could be higher or slower depending if the wind is tailwind or headwind.
That was most likely airspeed. The ground speed would have been much higher than 63 mph.