Is a drone worth getting?

[Catmandoo]

On 8/13/2020 at 7:56 AM, BlackRockBigfoot said:

One of those mini blimp models might be useful like they were discussing with the Falcon Project.

 

Poofy bags have resurfaced. How much helium is needed?  For a spherical poofy bag, the formula  is 4/3 x Pi x r³  to get an answer in liters. Lots and lots of liters.  One liter of helium can lift 1 gram.  Factor in air density, temperature and windage and helium lift assist is questionable. You can buy tanks of helium with a balloon filling fitting at welding gas supply places. Never done it, read about it on the internet.

 

Worked for 'Lawn Chair Larry' and he had too much helium. Don't try that one at home.

 

I can hear the numbers crunching already.

[hiflier]

Cost of helium? Depends on whether it's sold to the military or not. In 2018 a million cubic feet could be had at auction for around $300. Of course it would depend on its purity and then there would be the cost of storage and transport should one be the lucky person to get a million cubic feet by holding up a card with a number on it until the auctioneer says "SOLD!! TO THAT BIGFOOT RESEARCHER IN THE BACK ROW!"

 

It also means that if the military has a very large UFO type delta-shaped stealth blimp (like it was suspected of having between the late 80's-mid 2000's) at 600,000 cf. they could fill it with about $150-$200 worth of helium and be floating off in no time. A 300 ft long craft x 200 ft. across the stern, pointy in front that 20 ft. tall would have a total lift capacity of around 20 tons. Of course, on a rainy day neary half of its load capacity would be trying to carry all the rain water that collected on the upper hull surface. An estimated empty craft might run around 10 tons which would leave around an 8-10 ton cargo load capability. Unless it rains. In that case the thing had better be cargo-less or it's going down!

 

As far as drones go though, there's a lot to be said for being in control. A hybrid type might be interesting to design where the drone is very light due to a helium lift reservoir but the unit itself isn't neutrally buoyant, just lighter to conserve energy and remain airborne longer. I think a lot of energy gets wasted when a drone is moving slow and trying to maintain altitude. Some kind of helium assist might be beneficial so that the operator still has control of the craft. if speed is desired at some point then remotely eject the "balloon" to float off somewhere and then just operate the drone like normal. Then the device could remain on slow patrol for perhaps a couple of hours instead of say 30 minutes? If such a contraption could be rigged up then one could concentrate on noise and probably end up with a fairly quiet, if not nearly silent, unit?

Edited September 12, 2020 by hiflier

[SWWASAS]

Off the shelf blimp bags are the ones you see used for advertising at car dealers.      You can get them in various sizes to match your payload.     But unless you have a very large shop or aircraft hangar it is not something you are going to want to fill and take out on occassional weekends due to the cost of helium.   You would need a large vehicle like a big box van to transport the thing.   Wind is always a factor.    Much wind at all and you cannot make any headway against the wind.    Bye bye blimp.   If you want to take the risk and liability,   you could always generate hydrogen to fill the bag.    Better lift and easy to constuct a hydrogen generator to make it out of water.   But a small leak and one spark and you get to recreate the Hindenburg disaster.    

[Catmandoo]

It did not take long for number crunching in ' Helium factoids 105'. Good info. Hydrogen and helium are the smallest atoms. They have a 'leak rate' and they pass through materials. Current toy helium balloons live on the ceiling for a long time but eventually loose gas and drop.  Weather balloons are available but maneuvering in updrafts/ downdrafts would be a challenge.  Tethered balloons would be quiet.

 

6 hours ago, hiflier said:

If such a contraption could be rigged up then one could concentrate on noise and probably end up with a fairly quiet, if not nearly silent, unit?

 

Camera kites were developed before quadcopters.  A camera with pan and tilt would require serious load capacity of the kite. I can think of one WiFi network system that has an optimum range of about 500'.

 

 

34 minutes ago, SWWASAS said:

 But a small leak and one spark and you get to recreate the Hindenburg disaster. 

 

Hydrogen burns colorless. The hydrogen in the Hindenburg was compartmentalized in poofy bags. The poofy bags were sequentially punctured by the burning skin, hence no massive instant explosion. The skin was painted with a coating that is called 'dope paint'.  Analysis of the Hindenburg skin revealed that the dope paint of that time was similar to the composition of the solid rocket fuel that was used for the space shuttles. The reason that the Hindenburg used hydrogen instead of helium is that the US cut off helium shipments to Germany. 

Hydrogen would be good if used by non-smokers. More lift than helium and as SWWASAS posted, anyone can make hydrogen at home. Getting the hydrogen into storage tanks has risks. 

[hiflier]

8 minutes ago, Catmandoo said:

....the US cut off helium shipments to Germany.

 

And then in subsequent years Germany went on to become a top producer of helium. A couple of year ago an absolutely enormous deposit of helium was found in Tanzania (Africa). Something like 50+ billion cubic feet of the stuff. It's a by product of natural gas and the US built and set up a facility 0out Wet (Nevada? Utah?) to extract helium from the local natural gas reserves. And it was worth it because the purity of the extracted helium was very high.

 

But getting back to a hybrid drone idea, and I'm probably not the first to go there, it reminded me of McPhee's  infamous "Flying Pumpkin Seed", the Aereon 26, in the late 60's early 70's, which was a hybrid airship/airplane. So a hybrid concept isn't a new one:

 

[Catmandoo]

For you hifier:

 

http://www.kapshop.com/HeliKites/c20/index.html

 

I feel that if one is to have an inflatable camera lift system, that it should be shaped like a UFO.

 

KAP & BAP, kite aerial photography and balloon aerial photography are alternatives to 'drones'. The cost is not necessarily less than drones but the flight time can be substantial, pending suitable weather.

[hiflier]

Thanks, pretty cool but the idea behind a hybrid, of course, is at least some aerodynamic control even if winds are light and the ability to have an non-tethered approach. So I was thinking if Norseman added some passive lift onto his P4 Phantom drone he may get more airtime easier lift, less noise and still have control of the craft's capabilities regarding GPS. The chief advantage being longer battery life and longer time aloft depending on how much passive lift could be deployed and still have control even on a light breezy day. If the time only gets increased by 15-20 minutes it could mean almost an hour of flight time and surveillance. So instead of either all brute power or all passive lift there could be a middle road that has the advantages of both. I think that's where the Falcon Project may have stumbled? Because a completely passive tethered lift system has it's drawbacks- even if it could be non-tethered. The FP was simply too large to allow close surveillance and had the problem of dealing with ssiling only on "perfect" weather days wind wise. And deployment required quite a bit of lift gas and calls in judgement.

 

Hey, for all I know a hybrid drone would be ineffective as well but the idea of being able to cover more ground due to flight times sounds like there should be a happy medium somewhere. On the technical side one wold have to experiment with some math to determine how much lift would be suitable for the weight of any craft and still remain in complete control of it. Too much lift wouldn't be as good as say a lift package that would reduce the weight of a drone, say, by half? I could see using a light wind as an aid to using less prop rpm for staying aloft as well as forward speed. It may be that returning against a breeze wipes out any gains but at that point the ballonet could be deflated remotely to reduce drag?

 

Then again the pitch noise of the drone may start to sound a bit Donald duckish

 

Ok, quick calculation: To reduce the P4's weight by half one would need about 700 liters of helium inflating a 3.5 ft. diameter balloon (minus the wt. of the balloon. A 2.5 diameter balloon will reduce the P4's weight by a third. The P4 weighs just a little over 8 pounds.  

Edited September 12, 2020 by hiflier

[SWWASAS]

I think a good starting point would simply be to use weather ballons to hoist remotely operated cameras up a few hundred feet.   Totally noiseless and a BF may not even notice it or know what it is.  Certainly if you had low light cameras you might capture something during the summer at the Northern latitudes where there is a lot of twilight sky in the North.   Put a light in it and BF may think it is the moon and come have a look.   No reason you could not move around with it if you are careful not to snag the teather in the trees.   Anything different is worth a try.    Wandering around in the dark does not seem to be producing much.   

[VAfooter]

I believe the balloon option is an excellent solution, at least until it is proven not to be. However, as has been discussed here before, anything over 50 feet in altitude (I think) has to be approved by the FAA since it is tethered, stationary object and a hazard to aircraft. Then you have to put lights on it and such. That starts running the complexity and cost up dramatically.

[SWWASAS]

Yes to be absolutely legal at night you are correct at night,    Obstructions above 200 feet below a 1000 feet are the only thing the FAA charts or requires to be lighted.  In urban areas it is above 299 feetl.  Otherwise nearly everything tall would have to be lighted including trees.   And kids with kites would be regulated.   I have a 130 foot tall Douglas Fir in my front yard.       However no one is going to be flying full sized aircraft within a couple of hundred feet of the ground in mountainous areas at night.    Drones, both commercial and hobby, are legal up to 400 feet in the daytime without any blessing from the FAA.  I think any higher than 200 feet is reduces the image size to the point of not beign worth the effort.  If you get right down to it,   who is going to complain to authorities in the middle of the night in the woods.     If you are using hydrogen gas and set the forest on fire they might get excited about that.  

[VAfooter]

2 hours ago, SWWASAS said:

If you are using hydrogen gas and set the forest on fire they might get excited about that.  

 

You presume there will still be a forest to burn....

 

Thanks for clearing up the regulations. I thought the FAA got involved a bit lower than 200 feet, but a balloon that high could prove to be a valuable asset. It would be my luck that if I set out a balloon at 200 feet one night, that would be the night a private pilot gets lost and flies into it or the military decides to perform low level excercises in the area.... It would be like the barrage balloons of WWI & II.

[Catmandoo]

For further reading because you can not fly in wilderness areas and more:

 

https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprd3844690.pdf

[SWWASAS]

16 hours ago, VAfooter said:

 

You presume there will still be a forest to burn....

 

Thanks for clearing up the regulations. I thought the FAA got involved a bit lower than 200 feet, but a balloon that high could prove to be a valuable asset. It would be my luck that if I set out a balloon at 200 feet one night, that would be the night a private pilot gets lost and flies into it or the military decides to perform low level excercises in the area.... It would be like the barrage balloons of WWI & II.  

The military does and can fly at 200 feet but is restricked to higher clearance plains at night.    I did that kind of flying in the military for 15 years.    200 feet in the daytime for a civil pilot is hard/dangerous because of performance issues.    You have to be very careful to not fly towards a mountain that your airplane is not capable of climbing fast enough.   I was down there when I flew past what I think was a BF.   It is not comfortable flying that low in the mountains even in the day time.   At night it would border on being suicidal.     Catmandoo is correct in that airplanes cannot fly lower than 2000 feet over wilderness areas.  In my area wildrness areas are not where I would expect to find BF because they are not near water.   So I don't think that is too big a preventative factor.  

 

As for bending the rules,   I was listening to a talk show recently where an atourney was talking about the federal laws.    There are over 500,000 of them.  He said the average person likely breaks a federal law 2 or 3 times a day and likely does not know it.   In 10 years I of BF research I have only been engaged by law enforcement or Forest ranger twice.    I think one could reasonably fly a ballon camera without getting much attention, unless you are on a main road someplace.   

 

I discovered this planform of a drone and plan to build one this winter.   It can takeoff and land vertically,   transition to normail flight with the wings supporting its weight like a conventional airplane, then return to a drone quadcopter to hover or land.     Should get considerable flying time not having to support the weight all the time with the propellers.     The two front propellers tilt down for horizontal flight.    Should be a good camera platform with it mounted in the nose.  

[NorthWind]

23 hours ago, SWWASAS said:

 

 

I discovered this planform of a drone and plan to build one this winter.   It can takeoff and land vertically,   transition to normail flight with the wings supporting its weight like a conventional airplane, then return to a drone quadcopter to hover or land.     Should get considerable flying time not having to support the weight all the time with the propellers.     The two front propellers tilt down for horizontal flight.    Should be a good camera platform with it mounted in the nose.  

 

 

That's cool!

 

Do you have a link to downloadable plans for this thing?

[SWWASAS]

I don't even know the origin.  It was cool looking so got my interest.    I get the impression that this is fairly large.   There seems to be gimbal mounted camera under the nose so I am guessing the wing span is a couple of meters based solely on that.     I saw a cruder version someplace that was a package delivery vehicle but it was not as aerodymanic looking.   This was in a assortment of pictures of large drones and not identified.   ...     I have been modeling my whole life so really do not need plans.  But,   I have zero experience with drone electronics so that will take some study on my part.   Fortunately I have a son who works as an engineer for NASA JPL who has worked on three of the rovers on Mars as well as the one that launched a few weeks ago.   He is working on the next Rover already.    It will be a sample return verhicle that gathers the samples taken by the 2020 rover and returns them by rocket back to earth.    He has done drones for a hobby and is a good source of engineering advice.     I don't understand the inward canted rudder on this one and will probably make it vertical with the stabilizer on top like the OV-10 was designed.      I have wings from a large glider, that I expect to reuse.   Wings are not so fun to build.     The gull wing design makes it look cool but that adds complexity and weight to the design.  I think it may have been to get prop clearance.     I will likely try to eliminate that for simplicity.     The mechanism to tilt the forward props will be an interesting engineering project.   The similar planform I saw, and cannot find again,   used a single pusher prop rather than tilt the forward props.     This design would eliminate that motor as well as eliminate the drag when the aircraft is in forward flight.    The struts do not look like a good idea to me.    I will replace that with wire mounted wheels so it could land like an airplane if the rotor tilt mechanism or one of the motors fails.      Initially I plan to mount a plotwather type camera I already have in the nose that takes still pictures at intervals.     Should I get a helper to operate the camera,   I could change that to a moveable camera that returns the pictures via radio.    I will design the payload bay of the aircraft accordingly.      I would be happy to share the plans when they are available. 

Edited September 14, 2020 by SWWASAS