Mabou - thanks for highlighting an important part of drone flying.

400ft - 120m is fine for keeping our drones out of the way of civilian aircraft, as well as the 2 mile exclusion limits around airports.

However, our countries all have their militaries - one branch being the air force.  Royal, Canadian, US, Russian - whoever.

My point is that not all aircraft fly in the troposphere - and the low-level jets are just that.

UK law says our pilots can fly as low as 250ft or 75m in rural areas.  In specific LFA's Low Flying Areas - it can be as low as 100ft or 33m.


Our pilots would visit Alaska and Canada to carry out even lower flying, in NATO 'war games'.  Excercises Green Flag or Cope Thunder for example.


So - our drones are limited to 400ft altitude ( at point of take off) - but if a fast jet is hugging the ground at 100ft going high sub-sonic, best we keep out eyes (and ears) peeled.

Internet is a powerful tool to find out if you are flying in a low-level flying area - or corridor.



Best I know of is Mach Loop in Wales.

gt3rs Posted at 2017-9-13 01:24
Everyone here is telling you that is really hard to believe that they were so low. Why would they go so low?     I did explain to you how you can calculate and not pure guessing the distance, but instead you come up with story that a 400mm is not a telescope, I was using a 1.6 camera, it is cropped, etc...  Why you didn’t simply use the calculator with your image and data and post the result here?     Anyway here is the download to my image with exif intact: [view_image]     You will see that is taken with a 1Dx II with a 200-400 with 1.4x engaged at 490mm.   The 1Dx II uncropped image width is 5472 pixels. http://www.imaging-resource.com/ ... anon-1dx-iiDAT.HTM.  My image is 5472 pixel wide so it is uncropped. The FA 18 is 60 feet long https://en.wikipedia.org/wiki/Boeing_F/A-18E/F_Super_Hornet  The FA 18 takes 4695 pixel in width in the image.     So now do the calculation and see: https://www.scantips.com/lights/subjectdistance.html        [view_image]     You want a second proof: http://www.cambridgeincolour.com/tutorials/camera-lenses.htm you will see that you need 490mm on FF to get the 60 feet long fa 18 filling the frame at 820 feet.
If the F15 was at 400 feet you will have the plane filling the whole frame on a FF DSLR at 228mm, you with a FF at 400mm and the plane being so small in the picture ....
If they were at 400 feet with your 400mm it would be something like this (this is actually how it would be at 522 feet):https://photos.smugmug.com/Airpl ... /X2/RONN5782-X2.jpg[/img]

Also interesting to use a depth of field calculator to see how small the depth of field is on FF camera with 400mm lens even at 400ft.  If you think that at 400ft it would be in focus to infinity or that 400ft would be in focus when focused on infinity then you are very wrong.  Confirmed by the photo 2 above!

Rigger73 Posted at 2017-9-13 02:32
Mabou - thanks for highlighting an important part of drone flying.

400ft - 120m is fine for keeping our drones out of the way of civilian aircraft, as well as the 2 mile exclusion limits around airports.

If you are flying your drone in the Mach Loop area then please check the RAF low flying timetable and don't think of flying when they are active.  "high" sub-sonic means that you don't hear them coming until a few seconds before they arrive, I know from experience that 100ft with 2 seconds warning does not give you time to think about getting out of the way even when you are not flying a drone, and 100ft with a 60ft wingspan means the wingtip can be below tree height!

UK low flying timetable: https://www.gov.uk/government/pu ... -training-timetable

Hi Guys, ok, we are all a bunch of geeks... and it is really cool.  
That said, It feels like there has been a bit too much controversy in this thread, but such is the life of passionate like-minded people.  You definitely got my attention about my claims, so I dug a bit deeper to try to understand how the math could fly (heh...pun) in the face of what I experienced.
I took a look at the metadata for that photo.  (I was hoping the metadata would show how many feet to the item in focus (like it does on my video cameras), but apparently that is not included in metadata for photography).  

Although I had a 400mm lens mounted, it turns out  that I had pulled the zoom back to 212mm for that shot.  I remember (in that moment) having to back off the zoom in an effort to be able to find and frame the jet for the second or two it was available to me, but I didn't know I pulled that far back.  Also, the jet wasn't straight overhead when I shot these images.  Probably a block or more away.  So that takes care of part of the math-sleuthing of the situation.  
The other variable is that the jet was possibly a bit higher than I estimated by eye, but really, not by much.  I stood there and watched the jets fly by and I was able to see them over the trees when they were flying away from my house.  I still believe that they were hotdogging and were lower than they should have been, especially during the turnaround (which is over my house at the top of the hill).  Apparently many others thought they were too low as well, based on the number of calls to the police.  But none of us have evidence other than our own eyes (which as we know, can be fooled)..  

You guys rock.

gt3rs Posted at 2017-9-13 01:24
Everyone here is telling you that is really hard to believe that they were so low. Why would they go so low?     I did explain to you how you can calculate and not pure guessing the distance, but instead you come up with story that a 400mm is not a telescope, I was using a 1.6 camera, it is cropped, etc...  Why you didn’t simply use the calculator with your image and data and post the result here?     Anyway here is the download to my image with exif intact: [view_image]     You will see that is taken with a 1Dx II with a 200-400 with 1.4x engaged at 490mm.   The 1Dx II uncropped image width is 5472 pixels. http://www.imaging-resource.com/PRODS/canon-1dx-ii/canon-1dx-iiDAT.HTM.  My image is 5472 pixel wide so it is uncropped. The FA 18 is 60 feet long https://en.wikipedia.org/wiki/Boeing_F/A-18E/F_Super_Hornet  The FA 18 takes 4695 pixel in width in the image.     So now do the calculation and see: https://www.scantips.com/lights/subjectdistance.html        [view_image]     You want a second proof: http://www.cambridgeincolour.com/tutorials/camera-lenses.htm you will see that you need 490mm on FF to get the 60 feet long fa 18 filling the frame at 820 feet.
If the F15 was at 400 feet you will have the plane filling the whole frame on a FF DSLR at 228mm, you with a FF at 400mm and the plane being so small in the picture ....
If they were at 400 feet with your 400mm it would be something like this (this is actually how it would be at 522 feet):https://photos.smugmug.com/Airplanes/Lauberhorn-2012/i-K7Zds3M/0/2a9516eb/X2/RONN5782-X2.jpg[/img]

Gt3rs,

that is an AWESOME photo.

Nigel_ Posted at 2017-9-13 03:01
If you are flying your drone in the Mach Loop area then please check the RAF low flying timetable and don't think of flying when they are active.  "high" sub-sonic means that you don't hear them coming until a few seconds before they arrive, I know from experience that 100ft with 2 seconds warning does not give you time to think about getting out of the way even when you are not flying a drone, and 100ft with a 60ft wingspan means the wingtip can be below tree height!

UK low flying timetable: https://www.gov.uk/government/publications/operational-low-flying-training-timetable

I'm in awe of you very smart people and your sophisticated cameras.  
While I'm amused and impressed by this debate, I can assure everyone that those Mudhens were no lower than 500' AGL and it was more like 1000' to 1500' AGL.
Also, I know it sounds really really cool to talk about aircraft flying at 100' AGL and even getting some cool pixs of them that low.  However, all should understand that flying that low at near Mach snot is extremely demanding on the pilot's attention.  Matter of fact that is all he can think about at that altitude is not hitting the ground, nothing else, not navigating, not weapons employment, not defensive maneuvers/actions, hell even changing a radio channel is a life & death challenge, nothing but hoping you don't get a twitch that causes you to impact the ground.  At those speeds of about .9M, then at 100' AGL the time to impact with just 1 degree pitch down is measured in single digit seconds (~6.7s).  So, they fly that low at times no doubt about it, but they don't stay there for extended periods and even less so in terrain that is undulating.
Nigel is correct, short of a special circumstance all military low level routes are published/established along with their altitude blocks, typically surface to X.  Therefore, it is best you know where these routes are and avoid them like the plague if you intend to fly your UAV there.

gt3rs Posted at 2017-9-13 01:24
Everyone here is telling you that is really hard to believe that they were so low. Why would they go so low?     I did explain to you how you can calculate and not pure guessing the distance, but instead you come up with story that a 400mm is not a telescope, I was using a 1.6 camera, it is cropped, etc...  Why you didn’t simply use the calculator with your image and data and post the result here?     Anyway here is the download to my image with exif intact: [view_image]     You will see that is taken with a 1Dx II with a 200-400 with 1.4x engaged at 490mm.   The 1Dx II uncropped image width is 5472 pixels. http://www.imaging-resource.com/PRODS/canon-1dx-ii/canon-1dx-iiDAT.HTM.  My image is 5472 pixel wide so it is uncropped. The FA 18 is 60 feet long https://en.wikipedia.org/wiki/Boeing_F/A-18E/F_Super_Hornet  The FA 18 takes 4695 pixel in width in the image.     So now do the calculation and see: https://www.scantips.com/lights/subjectdistance.html        [view_image]     You want a second proof: http://www.cambridgeincolour.com/tutorials/camera-lenses.htm you will see that you need 490mm on FF to get the 60 feet long fa 18 filling the frame at 820 feet.
If the F15 was at 400 feet you will have the plane filling the whole frame on a FF DSLR at 228mm, you with a FF at 400mm and the plane being so small in the picture ....
If they were at 400 feet with your 400mm it would be something like this (this is actually how it would be at 522 feet):[/img]

doesn't look like he shot with 400MM to me... that looks like maybe 85mm equivalent on a crop sensor, probably 50mm maybe 55mm actual lens.  looking at the corner of the roof vs the jet, i dont know how tall his house but to me that looks like 85MM, not 400MM.. plus if it was 400MM, would definitely be more compressed effect on the roof corner.. this doesn't look a compressed bohkah...  


given its likely 85MM equivilent shot that the OP took, i will say that the jets flying boarderline 400 AGL..  maybe lower.. doesnt to me look like they are obeying their min floor requirments...

Mabou2 Posted at 2017-9-13 04:35
Hi Guys, ok, we are all a bunch of geeks... and it is really cool.  
That said, It feels like there has been a bit too much controversy in this thread, but such is the life of passionate like-minded people.  You definitely got my attention about my claims, so I dug a bit deeper to try to understand how the math could fly (heh...pun) in the face of what I experienced.
I took a look at the metadata for that photo.  (I was hoping the metadata would show how many feet to the item in focus (like it does on my video cameras), but apparently that is not included in metadata for photography).  

no way that is ~212mm shot dude..  let's assume your camera has minimal crop effect of 1.45X.  that is 307mm equivalent..   however, knowing a lot of crop sensor DSLR cameras have more then that say 1.6X that is 339MM.


now way that show is above 200mm full frame..   unless your house is 5 floors tall and your standing in a moat below the corner of the roof..  
something fishy here, im usually not one to call thigns out.. but if this did happen to u they do look bout 200-400 feet up AGL at 85MM, ill give you that!

ImHereToCrash Posted at 2017-9-13 19:18
no way that is ~212mm shot dude..  let's assume your camera has minimal crop effect of 1.45X.  that is 307mm equivalent..   however, knowing a lot of crop sensor DSLR cameras have more then that say 1.6X that is 339MM.

ImHereToCrash....  What?.... WHAT?

This is getting silly.  

The third floor corner of the roof appears in my shot.  I was shooting at 212mm with a full frame camera, and I wasn't even at ground level, I was on my back porch with is about 3' higher than ground level.  The shot is what it is. I shot at 212mm SOLID according to the metadata.

There is no great conspiracy here, there is nothing "Fishy", and this conversation is getting weird.

I simply posted a cool picture of a jet that kept buzzing my house.  I visually witnessed how low it was flying and estimated it to be about 200 feet off the ground.  The math shows that my visual estimation was incorrect so I didn't continue the argument and bowed to the fact that my visual estimate was flawed.  Not a problem.

Now you are saying something is "fishy" because I could not have possibly been shooting at 212mm, "accusing" me of shooting at 85mm?

I use the Canon 85mm L-series lens all the time for video productions where I am shooting inside small clubs and venues to do interviews with people.  If I shot those same people with an 85mm lens from 24 feet away (about the same distance of me standing on the porch to the roofline in my jet photo), they would be tiny in the shot.

This really is getting weird and is starting to get annoying.

Hi Mabo2,
I don't care about all the technical stuff, you posted a cool photo along with all the other photos & videos that have been posted with the creation of your thread, I have seen stuff I would not have normally seen & with Genghis 9's information on the topic has been an education, keep doing what you do best.
Regards
Eric

Eric ncfwa Posted at 2017-9-14 05:23
Hi Mabo2,
I don't care about all the technical stuff, you posted a cool photo along with all the other photos & videos that have been posted with the creation of your thread, I have seen stuff I would not have normally seen & with Genghis 9's information on the topic has been an education, keep doing what you do best.
Regards

Thanks Eric... MUCH appreciated.

Nigel_ Posted at 2017-9-13 03:01
If you are flying your drone in the Mach Loop area then please check the RAF low flying timetable and don't think of flying when they are active.  "high" sub-sonic means that you don't hear them coming until a few seconds before they arrive, I know from experience that 100ft with 2 seconds warning does not give you time to think about getting out of the way even when you are not flying a drone, and 100ft with a 60ft wingspan means the wingtip can be below tree height!

UK low flying timetable: https://www.gov.uk/government/publications/operational-low-flying-training-timetable

A sane voice - thank you Nigel.

Everyone seems to think low-level flying isn't something to worry about.

Me?  I think if someone is flying their drone up in Scotland somewhere, high and far - then chances are quite high of a near-miss incident.

Genghis9 has it right, that low-level flying needs a lot of concentration - well it did on older aircraft like the SEPECAT Jaguar and Harrier (both single seaters).  The Tornado GR1 to 4, not so much as it has TFR - Terrain Following Radar, allowing the pilot more time to fly the aircraft, and a navigator for sorting out the weapons as well as being in the right place.

Genghis - I think you'd be surprised at how long out pilots are hugging the ground for.  Think Cold War, and if it went bad, then NATO pilots were expected to infiltrate Warsaw pact airspace - under the radar - so they had to be low for extended periods.  Same happened in Gulf War 1.

Rigger73 Posted at 2017-9-15 11:34
A sane voice - thank you Nigel.

Everyone seems to think low-level flying isn't something to worry about.

There is some in-cockpit video somewhere on YT of a training mission through one of the UK low fly training areas, the pilot is giving a running commentary and sounds really relaxed!  Truth is they don't fly until they have had enough practice on the simulators that they can fly the plane without thinking about how to do it, and if they are the sort of person who can't stay relaxed while driving a car then they don't stay in the job for long.

Our low fly areas are actually quite a good place to fly drones above 400ft as long as you check the timetable before flying since the areas all have very little other air traffic.  You can still encounter low flying helicopters at times so you do need to stick to the rules but in open areas with good views you normally hear those coming in plenty of time since they tend to be very quiet areas.

Rigger73 Posted at 2017-9-15 11:34
A sane voice - thank you Nigel.

Everyone seems to think low-level flying isn't something to worry about.

Rigger73,
Appreciate the words...thank you
Since I am new to RC UAV flying and have already proven that my abilities need much work, I therefore purposefully don't state my resume here as it is really not fully relevant to this type of flying or this forum, although present discussion aside.
However, you should know I am both a Cold War Warrior and Gulf vet.  Therefore, I am not surprised at all about what combat aviators do flying nape of the earth and using TFR.  I do have direct knowledge of this type of flying from many persepectives.  If you wish to know more details, I would share them with you via PM, just drop me a line.
Take care and happy flying