I've been working on a new helicopter platform the last few months. Based on an MSH Protos heli which I chose because it's an extremely light weight platform, weighing in at only ~1200g without battery. It has a full belt drive which I much prefer to gears as it's quieter, lower vibration and more reliable. I've had a few problems with it because the belt drive makes a really awesome Van deGraaf generator... not a good thing on a UAV. But I solved that, and am conducting test flights now.
The flight controller is a modified PX4v1. I replaced the switching regulator with a MIC29300, so that I can run it on 2S direct with the servos. Main motor power is 4S 5000, typically this heli would run on 6S 3300. Using the MSH stretch kit and 465mm Spinblade Asymmetric blades. In otherwise standard form, this heli flew for 17 minutes on an old crusty battery, in -10C temperatures.
I have now added a subframe to hold an extra battery, FPV gear with a camera in the nose, and a vibration damped NADIR camera mount to be used for aerial mapping. The idea is to develop a mapping UAV that is superior to a multirotor, offering a valid alternative to a fixed wing for short to medium range missions. The VTOL capabilities would eliminate all the nastiness of catapults, and controlled-crash landings with onboard cameras in rugged areas. Even the price is attractive at about $400 for the basic kit with motor and ESC (no servos).
Specifications show the advantage of a heli platform. This machine has an AUW including the batteries and camera of only ~3kg. It is 80m long, and about 15cm wide not including the extended legs, and 30cm high. The blades fold for easy transport, without requiring any lose wires or vibration-prone electrical connectors as a folding multirotor does. It actually looks much bigger on the table than it really is. This seems to be very good compared to multirotors I've seen with the same performance. (payload and duration)
Vibrations are always a problem with helis, but manageable with the right design and construction techniques.
Arducopter really makes helis worthwhile. You could buy two entire heli systems including a Tx for the price of a single DJI Ace One non-waypoint controller. Or 7 for the cost of a single Ace One waypoint enabled controller. I strongly prefer the PX4 controller over the APM and Pixhawk, because it offers 32-bit performance in a small package that is easier to mount in a heli frame.
So does it work? I took it up for it's first photo tests yesterday, and it worked beautifully. Better than 80% photos are usable. It flies for 20 minutes in a hover with old, cold batteries (-5C). I'm hoping for closer to 30 minutes while actually moving (helis are more efficient moving than hovering), in warmer weather with new batteries. It should have an easy cruising speed of 15 m/s with little or no reduction in flight time. At 20 minutes, this would offer an 18km range, and 27 if it can do 30 minutes. If you wanted to do FPV and not mapping, you could configure it with a 3rd battery in place of the SX260 and fly for... 30-45 minutes, and a range of up to 36km. Top airspeed is still TBD, but probably 20-25 m/s.
Wind penetration and stability is excellent compared to both multirotors and fixed-wing. You could do a mapping mission in winds up to 40 km/h with little effect on stability or duration.
If the success continues, I'm going to consider building a large gasser heli. This would allow flight times up to 2 hours, or payloads on the order of 10 lbs for 30 minutes. So you could map large areas, or even perform light duty spraying operations. I'm thinking about local application of a herbicide for things like Giant Hogweed elimination, that sort of thing. Such a large heli does pose significant danger and should only be used in industrial, agricultural or remote areas.
Comments
Noli, I don't recommend either of these helicopter kits. They are made for HK by a manufacturer which produces poorer quality. You can tell because of the grey finish on the metal.
These ones are better:
http://www.hobbyking.com/hobbyking/store/__23037__HK_450TT_PRO_V2_F...
http://www.hobbyking.com/hobbyking/store/__24878__HK_500TT_Flybarle...
http://www.hobbyking.com/hobbyking/store/__24687__HK_550TT_Flybarle...
Hi Rob,
Thanks for your reply.
150 meters altitude and flying time of 30 minutes are good for me as long it can carry a canon camera (e.g. sx260) to take aerial photo.
I am reading some of your postings in some of the forums that you opted to use 550 frame to up to 600 size. I am now interested to do this now. I am thinking of getting HK-500GT and use 2 pcs of 5500 Mah lipo batteries
HK-500GT
http://www.hobbyking.com/hobbyking/store/__14573__HK_500GT_3D_Elect...
HK-600GT
http://www.hobbyking.com/hobbyking/store/__15408__HK_600GT_3D_Elect...
Can I put 2 pieces of 5500 MAh lipo batttery in HK-600GT frame?
Guy, I think trying to lift what a 700 heli can lift with a 5-blade 500 is a bit of a stretch. It probably could be done. But don't forget, that what hasn't been mentioned in previous discussions is that helicopters still obey the basic momentum theory of lift, meaning that the higher the disk loading, the less efficient it is. So while maybe it's possible to fly with an AUW of 50-60lbs on a 1m disk, you're not going to do it for very long.
I hope to be able to spend some time on the FB code soon, but it's likely to be a patch based on 3.1.
I do not know if there will be a 3.2 release for APM Helis, as I just don't have enough time to test it. If you guys want that, somebody will have to step up to help with the testing.
Noli: That is exactly what this blog is about. ;)
Yes, there's no reason why you would not be able to fly a heli at 150-350m with APM. I do believe that electric helicopters such as the one featured here would be a good option for mapping an area that could be covered in 20 minutes, which is to say, most "visual range" missions as required by most laws. With a 600 size, I would bet we could get the duration up to 60 minutes with the right power system and batteries.
And then a gas helicopter could fly 2 hours at 100 km/h, which is, IMO, as much range as most people could conceivably make use of while obeying VLOS rules.
And the nice thing about helicopters is that the VTOL capabilities mean that if you need longer duration, it's not a big deal to simply land and change batteries. Unlike a an airplane where every landing in an unprepared area is a crash landing, so you want to limit the number of takeoffs and landings.
Carles, I bought these Eagle Tree hall effect sensors, and they came with tiny little magnets.
Is the traditional heli with APM / Pixhawk using Mission Planner can be able to fly / cruise at the altitude between 150 - 350 meters?
Right now, I am thinking that traditional heli with APM / Pixhawk using Mission Planner can be a good alternative if can do fixed wing job of getting Aerial Photos (Aerial Photometry) for RS/GIS application (i.e. getting aerial photos that good for mosaicking, georeferencing and othorectification). Current, we use fixed wing for aerial photos (altitude 150 meters and 350 meters) but flying this fixed wing UAV requires a lot of pilot training.
rob, what type of magnet are you using for the hall effect sensor?
Guy: all else being equal, 3-5 blade heads are actually less efficient. The main reason they are used is to get a given amount of lifting power in a certain size heli. For example, if you wanted the same payload that a Blackhawk has with only 2 blades, it would need to be bigger, and then it wouldn't fit well on the ship. There are some other reasons, such as higher cyclic rate (the main reason for the Hughes 500 to have 5).
As I said, everything about helis is a compromise.
David: Exactly. No follower arms on the DFC. The pitch links are rigid, and drive the swash around. The problem is that when the head teeters, it stresses the links. It's a horrible thing to do. I really don't understand the point, other than "it looks cool".
Some parts on a 700 are the same as a 600. And you can easily stretch a 600 to 700. But typically a 700 kit will use slightly beefier components than a 600.
My Trex500 clone kit is on it's way. I'm really only getting the kit to make sure I have whatever bits and bobs I might need for the build, but it'll mostly be a completely custom setup. I'm probably going to make side frames from scratch with a very different layout from normal. Dedicated for carrying a compact camera up front. This will be the prototype before I do the same thing for a 700.
It's to bad they don't make short kits for Heli's like they do for some airplanes. You could pick your main frame and tail boom length, then buy the main shaft, rotor head, blade size and type,motor, etc. It would just be a little cheaper than building from parts. You buy a kit and right from the start there are components that don't serve this type of application real well. If I do another build it probably would be just buying the parts I want.
Carles, 550 and 600 by align share most of the same parts. 500 is another story. I think even the align 700 uses most of the same parts the 550 and 600 do except the main shaft size is bigger. I don't think the 500 will be easy to modify like you will want/need to.
Just looked at a DFC on the web. No washout arms?????
Regards
David Boulanger
Guy, in the past, before flybarless controllers were invented, flying a multiblade head was tricky, because they don't have flybars. But now, it's no problem at all. Any FBL controller, or the APM should have no problem.
-
7
-
8
-
9
-
10
-
11
of 28 Next