Holy Stone HS720E Brushless 4K Drone, $335.99 (holystone.com...)
Manufactured by Holy Stone (www.holystone.com)
Last updated 09-09-21
The Holy Stone HS720E Brushless 4K Drone (hereinafter, probably just called the HS720E) is a mid-sized (360mm L x 330mm W x 70mm T), surprisingly light (490g {17.280 oz.}) drone that features GPS stabilisation, EIS (Electromic Image Stabilisation), a rechargeable 2S (two cell) 2,800mAh Li:Po (lithium polymer) flight battery, and the ability to tilt the camera's lens over a 110° range -- from pointing forward and slightly up to pointing straight down.
This isn't a flashlight, household lamp, Christmas light set, or other thing that glows, but it *DOES* have a number of LEDs on its fuselage (this word is definitely *NOT* pronounced "fyoo SELL' uh jee" as Drake Parker from the TV program "Drake and Josh" would pronounce it; the word is pronounced "" , so what the hey
I love things that fly; that's why I took the bate and also why I added a seperate section titled "PRODUCTS DESIGNED TO FLY" on my website a number of years ago and created a new website just under a year and a half ago specifically for flying machines of this nature!!! I was also attracted to something that this drone has that many others don't...
1: It has GPS -- simply meaning that it can stably hover despite any mild wind and knows where 'Home' is.
2: It has brushless motors (I tend to avoid brushed-motor quads these days because of their very short life!)
3: It has EIS (Electronic Image Stabilisation) to help keep video steady and photographs in focus.
4: It has a gyro -- that means it's easy to fly even for a "craptastic" pilot like me.
5: It has all of those wonderful LEDs
6: It has an
optical flow sensor; this allows the drone to stay stable in the air even when GPS isn't present -- such as when flying indoors.
7: It has folding pylons (arms) and propellers; this makes the HS720E easier to store and transport.
The HS720E is in the lower-end of being HOBBY GRADE, rather than just being another run-of-the-mill pisson toy grade drone.
It's not puny for one thing (it isn't huge, but it isn't microscopic either); and it sports BRUSHLESS motors that deliver incredible amounts of power and have a far longer useable lifetime than their brushed counterparts.
It sports a 4K camera with a 130° FOV (Field Of View) and a 5.8GHz transmitter to furnish a live video feed to the app; both still photos and aerial video can be taken with it!
If you choose to use a memory chip that is rated lower than Class 10, you *MAY* see skipped frames, "jitters", unwanted intermittent video artifacts, and similar horse puckey.
The HS720E has a very substantial, sturdy feel to it; it does not at all feel flimsy or loose like many products of, "Hoo Phlung Pu" origin so often do.
When you deploy (unfold) the pylons (arms), you can tell at once that the HS720E just exudes quality!
In the last photograph above, you should be able to see a pair of TheRCSaylors Stickers affixed to the drone (clockwise from the top left you have Nate, Abby, Amelia, and Popeye) along with an Anti-Collision Strobe for Drones.
I believe that the HS720E can withstand winds of up to 22mph (35.42kph) thanks to that GPS stabilisation!
This quadcopter is a bit more complicated to get it to take off than your average toy-grade drone...here's how to get it off the ground:
As with any rechargeable product, charge the drone first, insert a Class 10 or higher 4GB+ MicroSD memory chip into the drone, install two AA cells into the radio, and then you can pretend to fly a humongous dragonfly (well, that's what kitty cats would think it was if it were designed to be flown in a small living room -- you CAN fly it indoors, but you'll want a decent amount of space such an empty two-car garage at minimum!)
First off, load the app called, "Ophelia Go" (the Android version from Google Play) onto your 5G WiFi cellular telephone handset.
1: Turn the radio on by sliding the ribbed switch located just below and to the left of the righthand joystick to the right until it stops.
2: Unfold the pylons (arms) starting with the two front ones. Once that is done, unfold the two rear pylons. Place the drone on the ground.
Press and hold the POWER button on the drone (it's located on the top of the drone's fuselage near the front); the drone will emit a short series of tones.
At this point you may deploy the "antennae" -- or leave the righthand one folded. It appears to be a decoy added to the radio for cosmetic purposes; however the lefthand antenna is genuine.
3: Go into your phone's WiFi settings, and connect the one named Holy StoneEIS {string of letters and numbers}.
Then launch the app.
4: At this point, you'll need to perform a geomagnetic calibration of the drone. Pull both joysticks on the radio down and to the right. All of the lights on the undersides of the drone's pylons will flash a light green. Rotate the drone horizontally several times and then check the lights. When they change to dark green, turn the drone so that its camera faces either up or down, and rotate the drone several more times. When the lights on the front pylons turn red, then you can place the drone on the ground.
When all of the drone's LEDs turn steady-on, you're ready to take off.
Pull both joysticks downward and inward (or downward and outward) to start the motors at idle speed. Now, push up on the left stick or press the Auto Takeoff button on the remote near the upper left corner, and the drone should now blast off and possibly leave an expanding cloud of dust (if you launched in a dry, dusty area anyway).
Congratulations, you're now a pilot!!!
For additional instructions & tips on how to fly, please read the instructional material that comes with the product.
On the remote control, slide the ribbed switch to the left. On the drone, press & hold the "OFF/ON" button for a couple of seconds (until all of the lights on the drone have extinguished), and then release it. This should neutralise both of them.
Fold everything up, place the items back into their form-fitting compartments inside the bag (the radio goes near the upper right of the bag; the drone fits near the left side of the bag), zip the bag up, and go on your merry way.
The app records video to your mobile device whether you want it to or not; you'll want to go into the device's File Manager and delete them periodically or else you'll start seeing errors and other issues regarding low memory. *
If you're recording video and wish to take a still photograph, you must first neutralise video recording. Then take your still photo(s), and then restart video recording.
Videos are saved in clips of approx. 1,500,000 bytes (~5:00 runtime) so don't be surprised to see multiple videos on your MicroSD chip after each flight.
Most droners (drone pilots) prefer their flight videos split up this way; that way, if one video clip is fuxxored (corrupted), you don't lose the whole flight.
You can fly the HS720E strictly-dictly LOS (Line Of Sight) -- no FPV device is necessary even for preflight calibration.
If signal to the app is lost in-flight, the drone should automatically reconnect when it acquires signal again. Some HS720E owners report that they have to manually reconnect, but my particular HS720E does this automatically.
Time from unzipping the case to getting the drone in the air is a modest 2:18 (timed on a stopwatch).
The battery in the HS720E is rechargeable.
To charge the Li:Po battery in the HS720E, plug the furnished charge cable into any free USB receptacle on your Pee-Cee or Mac computer.
Plug the smaller end of the USB cable into the charger. A red LED on the charger should now come on.
Plug the battery into one of the two bays located on that piece connected to the charger (open the little door over the battery bay first if necessary).
A green LED on the charger should now begin blinking. When this light turns steady, you may safely umplug the battery from the charger and unplug the charger itself from your computer.
Fully charging the HS720E's battery should give you approx. 26 minutes (advertised) of flying time.
Charge time from a battery that is nearly flat (it was well into stage 1 LVC) was timed at 4:23 (for one battery) and 4:28 for a second one.
A third charge cycle (from well into stage 1 LVC) was measured at 4:14.
You may plug a second battery into the second battery bay on the charger if desired; please note though that only one battery will charge at any given time. While the first battery is charging, the green light on the charger corresponding to that battery will flash; the light corresponding to the second battery will also flash, but MUCH MORE SLOWLY. This indicates that the battery is indeed connected to the charger but is waiting its turn.
To change the AA cells in the radio, slide the battery door off, carry it to the top of the basement stairs, and kick it down those stairs into the basement crawling with thousands of hungry caddisfly larvae that need to have a wee -- they'll think it's something yummy to eat and start chewing on it, but quickly find it unpalatable, so they all pass micturition on it...O WAIT!!! YOU'LL NEED THAT!!! So just set it aside instead.
Remove the two used AA cells from the compartment, and dispose of or recycle them as you see fit.
Insert two new AA cells into the compartment, orienting each cell so its flat-end (-) negative faces a spring for it in each chamber.
Finally, slide the battery door back on.
Aren't you glad you didn't kick that battery door down the stairs to all those hungry, hungry caddisfly larvae that really need to go pee-pee now?
FWIW: caddisfly larvae are aquatic insects; they live in fresh water such as ponds, slow-moving rivers, lakes, etc. so you aren't going to find any in the basement.
This R/C drone is meant to be used as a toy in a large dry area outdoors or a large indoor venue, not as a flashlight meant to be carried around all the time, thrashed, trashed, bashed, and abused; so I won't throw it against the wall, stomp on it, viciously chuck it at one of those wall-mounted porcelain uranators to see if it becomes broken (the drone, not the uranator!), try to drown it in the {vulgar slang term for a fudge bunny}bowl or the cistern, run over it, swing it against the concrete floor of a patio, bash it open to check it for candiosity, fire it from the cannoñata (I guess I've been watching the TV program "Viva Piñata" too much again - candiosity is usually checked with a scanner-type device on a platform with a large readout, with a handheld wand that Langston Lickatoad uses, or with a pack-of-cards-sized device that Fergy Fudgehog uses; and the cannoñata is only used to shoot piñatas to piñata parties away from picturesque Piñata Island), send it to the Daystrom Institute for additional analyses, launch it into the upper atmosphere of Gamalon V** so that chairman Sonji gets all piddled-off about it, or inflict upon it punishments that I might inflict upon a flashlight.
This drone has foldable pylons (arms) and folding props; this makes transport and storage a whole lot easier.
The drone uses 2.4GHz RF radiation to communicate with its radio, and its camera uses 5.8GHz (802.11ac or just 5G WiFi) to relay its photographic and videographic data back to your smartphone or tablet.
There is an optical flow sensor on the bottom of the drone; this helps to maintain the drone's position at lower altitudes. The ambient light level must be fairly high in order for this optical flow positioning system to function though, so please do not expect it to function on night missions.
Optical flow is functional to 5 meters (16.40 feet) in altitude.
There are also two bright white landing lights on the underside of the drone's fuselage; you may energise these prior to landing if you've made one of those pesky night missions.
I just love the living tweedle out of the carrying case! Everything (and I do mean ***EVERYTHING***) that the HS720E comes with fits neatly into cutouts in the fabric-covered substance (unknown, though probably very heavy cardboard) for them (and a noncloseable pocket on the inside of the bag -- which is great if you wish to bring along extra flight batteries): the drone itself, the transmitter, all spare props, a second flight battery, and the charger & its cord).
The mobile phone holder on the radio can accomodate handsets up to 91.80mm (3.61") wide.
The camera lens has a 130° wide-angle FOV that will allow you to capture more detail and it features a 1/3" Sony CMOS sensor.
One thing that I noted immediately upon opening the box was just how heavy the kit was.
So I plopped it on my scale, and received a weight of 1.783kg (62.720 oz. {3.920 lb})
This includes the drone, the radio, two flight batteries, two AA cells in the radio, the instructional materials, the battery charger, and all of the spare parts plus the case itself.
One thing that piddles me off about this drone is that there is no stage 1 LVC (Low Voltage Cutoff) -- that is, when the drone's flight battery peters out, the radio will start beeping, and the drone will automatically begin landing. Yes, you can still steer it, but if you're fairly far away and low in altitude (esp. over water), you could very easaily be SOL.
IMPORTANT UPDATE!!!
Actually, additional testing has revealed that there *IS* a Stage 1 LVC; in this mode the lights on the drone's pylons (arms) will be all red, and a yellow bar on the app screen indicates that the drone's battery is starting to peter out and limits your altitude to 30M and distance to 100M.
This is a screen dump (yes, it's really called that!) of my FPV device showing the stage 1 LVC warning -- look at the text directly below the yellow bar at the top of the display.
As a direct result of this finding, I've upgraded the drone's rating and given it Trophy Case placement.
Video showing that the Holy Stone HS720E is one "tuff" cookie -- this person's HS720E drone spent two weeks dredged in a lake under 3 feet of water and it still performs like it was just taken new out of the box!!!
Video was used pending permission from the author.
ALL OF THE FLIGHT VIDEOS ARE ON THEIR OWN WEB PAGE
SO THAT THIS EVAL. WOULD NOT BECOME TOO CUMBERSOME!!!
Photograph of the radio (transmitter) in its feral state.
Photograph of the radio (transmitter) for this drone with a cellular telephone handset clipped into place.
Photograph of the underside of the drone, specfically so that you can see the camera for the optical flow positioning system and the two landing lights.
A quartet of aerial photographs taken by this drone; click on them to see the full-sized versions (they open in a new tab).
Spectrographic analysis of the OLEDs in this drone's radio.
I don't see OLEDs that often; that's why I performed spectroscopy of these.
The raw spectrometer data (tab-delimited that can be loaded into Excel) is at hs720e.txt
TEST NOTES:
Test unit was purchased on Ebay on 01-07-2021 and was received at 6:45pm PST on 01-14-2021.
** From the Star Trek: The Next Generation episode, "Final Mission".
UPDATE: 05-12-21
I went to fly it yesterday morning, and it was deader than a doorknob.
That is, it failed to power-up even with both batteries that were known to be fully charged.
Therefore I have no choise but to issue that dreadful, "" icon, denoting that total product failure has occurred.
Shame, as I rather liked this drone.
UPDATE: 05-16-21
I found that if the drone is lightly "spanked" while repeatedly pressing the "POWER" button, it does indeed turn on.
However, the drone is rather unresponsive in the air, so I may not be flying it much longer.
UPDATE: 05-18-21
The drone now fails to unlock, and is therefore unflyable.
UPDATE: 05-25-21
Just for $#¡7$ and giggles, I took it out for a flight yesterday.
It turned on immediately, and after just a bit of coaxing, I got it to spin up. I took it up and successfully flew it.
I took it for a second flight later in the evening and it successfully spun up and launched.
UPDATE: 08-17-21
It's Jim, dead!!!
The product now fails to power-on no matter what I try -- and yes, I was certain that both flight batteries that I tried were fully-charged.
Therefore, I have to append the dreadful, "" icon to is listings on this website at once.
UPDATE: 08-19-21 BEWARE I LIVE!!!
I had an epipheny early yesterday morning...
I used the butt-end of a laser pointer (dia. 7.10mm) to actuate the drone's "Power" switch, and what do you know -- the damn thing turned on!!! :-)
I found the actual problem. By taking the top of the drone off, you can plainly see the Power switch on its own narrow PCB, screwed down to the drone's interior. By shorting the (+) and (-) contacts on that PCB with a piece of wire, the drone immediately powers up. I unscrewed this PCB and found that the wires running to it are more than long enough to bring it outside the drone's body, so all I really need do (for a Band-Aid solution anyway) is bring the little piece of wire or a bit of crumpled kitchen aluminum foil with me to my flying venue and I'm off and running!!!
UPDATE: 08-21-21
On a flight that I made on 08-20-21, the drone apparently developed a mind of its own, it crashed *HARD* into a fence, breaking off its starboard (right) front pylon (arm). The camera is also totally and completely fuxxored -- the Y-axis can no longer be adjusted -- the camera now points straight down. :-(
Since I'm neither qualified nor capable of effecting the type of repairs that this drone now requires, I've declared it a total loss. :-(
Update: the camera is not fuxxored at all; the Y-axis adjustment from the radio does indeed function.
I'm going to attempt to repair the broken pylon with -- what else -- duct tape and see if I can bring the drone to flyable condition, but I can offer no guarantees here. I paid enough for this drone ($335.99) to make this repair attempt worthwhile.
I later determined that the camera's Y-axis adjustment is OK after all, so all I really have to concern myself with is that busted pylon.
UPDATE: 08-22-21
Here is a photograph of the temporary repair that has kept the drone from being binned (thrown away)
UPDATE: 08-23-21
The reason that it flew so poorly yesterday was found to be that the port (left) front pylon was partially disengaged from its receptacle. Once I popped it back into place and relaunched, the HS720E flew like it was never in a wreck to begin with!!! :-)
UPDATE: 09-04-21
Here is a photograph of the temporary repair of the drone while it was flying that I offer as proof that the repair was indeed successful:
UPDATE: 09-09-21
I was flying last evening shortly before sunset, when the drone started making a funny noise. Shortly after that, it summarily fell out of the sky.
A cursory examination in the field soon revealed why:
Since I'm neither qualified nor capable of effecting repairs, the drone is now a total loss, and the dreadful, "" icon must now be appended to its listings on this website at once.
MANUFACTURER: Holy Stone
PRODUCT TYPE: Medium-sized hobby-grade drone w/ GPS and EIS
LAMP TYPE: LED
No. OF LAMPS: At least 28 (17x green, 8x red, and 2x high-power white in drone, OLED display in radio)
BEAM TYPE: N/A
REFLECTOR TYPE: N/A
SWITCH TYPE: Pushbutton on/off on drone, slide switch on/off on radio
CASE MATERIAL: Plastic
BEZEL: N/A
BATTERY: 1x 7.40V 2,800mAh Li:Po for drone, 2x AA cells for radio
CURRENT CONSUMPTION: Unknown/unable to measure
WATER- AND RHINOCEROUS MICTURITION-RESISTANT: Very light sprinkle-resistance at maximum (though if a rhino really does go poddy on it, you've got FAR bigger problems than a stinky dead drone, hahaha!!! )
SUBMERSIBLE: ¡¡¡SATANÁS LLEVA UN PAÑAL SUCIO, NO!!!
ACCESSORIES: Carrying bag, USB charging cable, charger, 2x flight batteries, 4x spare blade sets, 8x Phillips screws for props, Phillips screwdriver
SIZE: (Deployed): 360mm L x 330mm W x 70mm T; (Stowed): 180mm L x 95mm W x 80mm H
WEIGHT: 490g {17.280 oz.} (incl. flight battery & MicroSD chip); battery alone: 159g (5.61 oz.); radio: 265g (9.35 oz.)
COUNTRY OF MANUFACTURE: China
WARRANTY: 30 days
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" 
, so what the hey
" icon, denoting that total product failure has occurred.
)
