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Aug 03, 2019, 09:50 PM
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Mini-Review

FX B17 Micro from Banggood


I received a review copy of this plane from Banggood. However, my review opinions are not influenced at all by the fact I received a free plane.

Banggood has a special deal on the plane at the moment, and the link is:

FX B17 Airplane RTF: (code: BGFB4W2, US$42.99)

They also have some special deals on some radio control products here.

I should say at the outset that there are a couple of problems with this plane which mean you will NOT be able to fly it successfully out of the box unless you fix them. It's not too difficult to do so, but it did mean that my initial experience with it was a frustrating one, and that's why I warn you. I give details below.

It comes from the Fei Xiong company, which is well known for the Fly Bears range of very basic two channel differential thrust planes. I have never flown any of those, but they generally seem to get good reviews. They are named FX 8XX where the XX are two digits that vary according to which plane it is.

This one arrived with no damage although the corners of the box were slightly squashed. This would only matter to you if you are buying for resale. The plane is packed in polystyrene so very well protected. There is a manual, but from the pictures on the front it appears to be for the Fly Bears range, with no picture of the B17, and of almost no value for assembling or flying this plane. However, assembly is extremely simple – you glue on the vertical stabiliser, push the three wheels into the appropriate slots, and that’s it. There is a tube of glue supplied, but instead of opening it I used a little UHU Por.

The plane uses differential thrust and comes with a very simple two channel controller. I do mean very simple – no dual rates, no trims, an on/off button, a light and two sticks. Throttle on the left slider, yaw on the right. A blue light that flashes when the switch is pressed, and goes on solid when the bind is achieved. You need 3xAA batteries which are not supplied for the transmitter. You fit the battery to the plane, turn on a small switch on the bottom of the plane, whereupon a blue light near the switch starts to flash. Turn on the transmitter, blue light on it flashes, then you push the throttle stick to its maximum and back to the bottom, whereupon blue lights on plane and Tx go solid and the plane is bound. Then applying throttle will cause the two inner props to spin. There are only two motors – the outer props are dummies that spin with the airflow. They appear to be the familiar 8x20mm brushed motors. The motors spin in different directions, so there are two left hand and two right hand props. One spare prop of each type is included with the kit. Don’t fit the wrong prop to a motor!

It does not seem to matter whether you switch the Tx on first, then the plane, or vice versa. Note that the bind process is NOT correctly described in the manual. In particular it doesn't say anything about moving the throttle stick to max and back to complete the bind.

Now this is where the fun started. When I cautiously advanced the throttle the first time, as I reached about one third throttle one of the props flew off.
I retrieved it after a brief search, replaced It, started again and exactly the same thing happened. I’ve sometimes had this problem with quadcopters, so I used the same fix. I put a small piece of thread into the shaft hole in the prop, which fortunately goes right through to the front of the prop, and pushed the prop on again. This time it stayed on right up to half throttle, whereupon the prop on the OTHER side flew off! So I applied the same fix to it.

Since then I have had the same problem a couple more times, but now using thread and a tiny amount of CA glue, I seem to have stopped it.
If you do lose props because of this problem, as well as the spares you can use the outboard props to replace the powered ones.

Anyway, the next step was to try to fly it, so I took it to my favourite park. I didn’t do any trimming, just fitted the battery in the battery bay, removed the wheels and did a hand launch at a pretty low throttle setting. The plane flew level out of my hand with a slight roll to the left. I applied some more throttle to try to get it to climb – NO CLIMB AT ALL! More throttle, still no climb. By this time losing height, probably because of the slight roll to the left. Plane soon nosed in. Fortunately, since it’s made of EPP, it’s more or less indestructible.

Back to the drawing board. I took the plane home and inspected the horizontal stabiliser carefully. There are hinges molded into it, and a slot clearly for a control horn. There are tiny fillets that if removed with a modelling knife, would free up the elevators. This plane has been designed for THREE channel use, or at the very least, with three channels in mind.

So I freed up the elevators, fixed them with a tiny amount of up elevator and returned to the park. This time I was able to make the plane climb, and was able to fly it quite successfully. However, when I took it up high and throttled off completely, it immediately dived. Very nose heavy.

The battery is a 450mAh one, weighs 14g and compared with other planes I have, that seems overkill for a plane that only weighs 43g without a battery, and just under 41g without the wheels. So I tried a 300mAh battery with the same plug, weighing 9g. With it the plane flies well and is not so nose heavy. So that’s what I am using now. I haven’t done an assessment of flight times yet.

I’ve also flown it inside on a double basketball court. Turn authority is sufficient for that, but I wouldn’t be confident flying it with other planes in the air, as it’s not very manoeuvrable in such a space. It’s more suited to the outdoors. Landing was a problem indoors, as it's impossible to flair, so you have to land "hot" and immediately cut the throttle.

So in summary, to have success with this plane you need to:

1. Solve the problem of props coming off.

2. Somehow get some control of the pitch. This I have done by applying a tiny amount of up elevator, and reducing the amount of nose heaviness by using a smaller battery. It might be possible to keep the original battery but try to move it further backwards in the fuselage. There does seem to be room for that. I will be continuing to work on the elevator and battery variables to try to get the optimum flying experience.

As soon as the weather improves here I hope to be able to do a video flying outdoors which I will add to the thread.

I expect some people will be interested in the scale appearance of this as a B17. Frankly, it's pretty ugly out of the box, mainly due to the colours, or lack thereof. It doesn't help that the tail wheel is far too large and about 20mm too far forward. I simply left if off and put a big-headed pin back at the spot where the tail wheel should be, to improve the way the plane sits on the ground (see photo). If I have the motivation I will make a scale size tail wheel later.

Despite the ugliness, the proportions are pretty right for a B17 apart from the tail wheel. If you fit the main wheels the way I have, rather than the way they are fitted in the photos on the BG Web site, they don't look too bad. Also the 3 bladed props look pretty faithful to the original, if you can keep them on

There is only one gun turret, above the cockpit, whereas some B17s had three more. However, you could add some if you wanted to.

I think it could be greatly improved by appropriate painting.

I'm also thinking that some people may want to rip out the electronics and put in a lightweight four-channel brick. I think that could be practical, as the weight is not too bad at 43g without battery. The 8x20mm motors are far more than are required, so replacing with 7x16s would save some weight.
Last edited by 1auriec; Aug 03, 2019 at 09:59 PM.
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Aug 04, 2019, 11:51 AM
Way to much free time!
CorvetteC5's Avatar
Nicely done review!

I'm reminded of the Silverlit RC Speedy Plus airplane sold by Radio Shack during the Christmas season of 2013. That one had 4 powered motors with 2-bladed props. I converted mine to DSM2 and even recorded a flight video earlier this year. Adding pitch control is very helpful, naturally, as is mixing a working rudder to the motor differential. Just FYI.
My blog for it:
https://www.rcgroups.com/forums/show...4-Motor-Bomber
Last edited by CorvetteC5; Aug 04, 2019 at 11:56 AM.
Aug 04, 2019, 08:45 PM
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Quote:
Originally Posted by CorvetteC5
Nicely done review!

I'm reminded of the Silverlit RC Speedy Plus airplane sold by Radio Shack during the Christmas season of 2013. That one had 4 powered motors with 2-bladed props. I converted mine to DSM2 and even recorded a flight video earlier this year. Adding pitch control is very helpful, naturally, as is mixing a working rudder to the motor differential. Just FYI.
My blog for it:
https://www.rcgroups.com/forums/show...4-Motor-Bomber
I had a look at your post, and that plane does look very similar to this B17 in the basic idea . Yours certainly does well indoors, quite slow and plenty of turn authority. Good work!

I do think the B17 would be quite suitable for the 3 channel treatment. I doubt I'll do it, but I will be very interested to see what result others get if anyone tries it.
Aug 07, 2019, 02:56 AM
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Video of flight


At last the wind and rain stopped long enough for me to do a flight video. For this flight, I used a 300mAh battery rather than the supplied 450mAh one. You can fly it with the supplied one though, but because it makes it rather nose heavy you will need a bit more fixed up elevator built in. I have attached a photo showing how much up elevator I used with this battery. As you will see, I just pushed the end of a toothpick into the fuselage right at the trailing edge of the elevator to lift it up by a tiny amount, around 2mm, and did the same on the other side. I also applied a tiny piece of sticky tape to stop the elevator moving in the slipstream.

Trying the same setting with the stock battery I had difficulty getting it to climb, but I think one more millimetre up elevator would be sufficient to fix that.

Apart from that, it was stock standard, but for flying outside I have removed the undercarriage. Note also my remarks in the first post about keeping the props on. So far my method with thread and a tiny amount of CA glue seems to be working.

I feel much better about this plane now the issues I found at the start have been resolved. It's very stable and easy to fly. I think the gyro helps a lot - it doesn't have a lot of dihedral, so I think without the gyro it would be a lot more challenging. It's a shame though that it has flaws out of the box - non RC literate buyers are likely to be disappointed, yet it's not a bad plane for beginners if set up correctly from the start.

Flight time even with the 300mAh battery is more than adequate - I estimate 8-10 minutes, but I will do a more accurate timing and post it later. I did run the battery right to the point where I noticed a marked drop off in the ability to climb. Then as I came in to land the nose suddenly dropped and I realized the motors had cut out. When I picked it up I noticed the blue light on the plane was flashing instead of being on solid, so I suspect it gives a low voltage warning this way but it's hard to see while it's in the air. When I checked the battery it was at 3.4V, which is a bit lower than I would like, so I'm going to try to see the light flashing from the ground if at all possible.

FX B17 Micro Radio Controlled plane from Banggood (3 min 0 sec)
Aug 13, 2019, 03:53 AM
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B17 Flying Indoors


I had a chance today to fly this plane indoors, so here's a very short video. As you can see, the turn authority is a bit limited, but I did manage to make it turn enough not to hit the walls!

Flying it like this is a bit counter intuitive. To make the turns tighter, you need to throttle right off while turning. The plane has been programmed so it automatically speeds up the motors a bit in the turn, which makes sense I suppose as it would lose height otherwise, especially since it doesn't have much dihedral.

BTW, one thing I didn't mention in the original review is that I did test to see what happens if you lose signal from the transmitter. I throttled up the motors and turned off the transmitter. The motors stopped after about 1 second. It may seem obvious to program it that way to avoid flyaways, but I have found at least one where that hasn't been done!

FX B17 flying indoors (0 min 51 sec)
Aug 13, 2019, 07:17 PM
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Comparison with C-17


As well as this B17, I also have the somewhat similar two channel differential thrust C-17, also available from Banggood here. Now I feel I am pretty familiar with both of them.

So which of the two is better? The C-17, by far.
- It flies much better, and needs no fixes to fly well out of the box
- It has a better transmitter, with trims and dual rates (although admittedly the trims are reversed on mine!)
- It looks much more realistic, mainly because of the better colour scheme
- There is good parts support, with spare props, motors, receiver, battery all available cheaply from Banggood ( hopefully these might eventually appear for the B17)
- The battery is more suited to the plane and much lighter (actually I have been using the C-17 battery in the B17, and it's perfect, with flight times of about 10 minutes)

At the moment it's also much cheaper on BG, only about half the price of the B17.

So why would anyone buy the B17? Well, a lot of people have great affection for the Flying Fortress, and I think this one has good potential for hacks such as fitting it with a three or four channel brick. I think it would fly well if this were done properly, as it's quite light enough. Indeed as I said in the review above, it's even got the elevators already fitted out for three channel. You could also replace the 8x20 motors, which are far too much, with four small ones, such as 4 or 5mm diameter.

Repainting would also greatly improve it.

On the plus side, I have proved that the plane is virtually indestructible because of being made almost entirely from energy-absorbing EPP .

If anyone is interested, my flight video of the C-17 is here.


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