Just got a Blade 400 without Tx and Rx (PNP type). The Blade 400 is all stock. I had a Futaba 7C Fasst Radio System ready to be installed in the Blade.
I installed the Rx, setup everything, collective, mechanics and gyro, fired it up, and it was flying like a $10.00 toy heli: Tail wouldn't hold, heli flying lazy with the tail all over the place in climbs and descends, and the batteries weren't lasting more than 4 minutes or so. What a nightmare for a guy with experience in helis for many years... .I mean, I setup everything the way I should and didn't have a real explanation why the heli was acting like that.
The installation of the 7C Fasst Rx in the heli was a little tricky due to the limited space in the frame of the B400. I was able to install it by plugging in the first three plugs, then placed the Rx inside the frame compartment, and then finished plugging the other plugs. After that, I applied the double face tape to the Rx. I also secured the Rx to the frame with a tie wrap lightly tightened around the frame and Rx. Ah, I had to move the ESC forward to make room for the Rx.
In subsequent flies, I tried everything I could. As I said, I'm an experience heli flyer with 5+ years of intensive experience with 90's helis, setting up different brands of helis, including mechanical and electronically controlled CCPM, good gyros and servos, and never had problems like that couldn't be fixed or explained.
I then recalled reading the stock ESC isn't programmable and asked myself if the throttle channel of the 7C would be matched to the ESC speed range, i.e., when having the Tx throttle stick at maximum and at minimum deflection would have the ESC at its maximum and minimum outputs accordingly.
To test that, I removed the four screws that hold the motor to the frame, and moved the motor assembly until the pinion cleared the main spur gear. I also kept applying force between the motor assembly and frame to prevent it to move back and touch the spur due to the vibrations that are present when the motor runs.
I connected the battery, waited for the two beeps, and started up the motor by raising the throttle stick. Before raising the throttle stick more, I waited the 15 seconds of the soft start feature of the Blade 400 ESC to elapse, then I continued to raise the throttle stick. To my surprise, I heard the motor stop raising speed a little above middle stick, and from there, the speed was the same until I reached full stick. There was no doubt this meant the maximum speed was reached well before the Tx throttle stick reached maximum deflection. In other words, this meant the throttle channel output wasn't calibrated to the ESC throttle input signal. Note that if you have an aftermarket and good programmable ESC, you shouldn't have this problem because you'll have a setting in the ESC programming menu that actually calibrates the ESC to the minimum and maximum signals of your Tx. But this isn't the case when you are using a non programmable ESC, as the stock ESC the Blade 400 is. This is also true in many other low price electric helis Brands like the Esky helis, that use non-programmable ESC's.
After I discovered the Tx and ESC weren't matched, I then returned the throttle stick to low, and then entered the EPA (aka End Point, or ATV) of the throttle channel. Now I raised the throttle stick again to the maximum setting, and started lowering the EPA value until the motor rpm's started to drop. Then, I raised the EPA again now taking note at the numbers when the motor rmp's stop raising. To my surprise, it was found that a value of 48% was enough to reach the full speed output of the ESC!! I end using 50% as a safety margin. I then did the same procedure in the lower side of the throttle stick (going to the slow speed) and found the same situation I found in the high speed, and ended also setting the EPA at 50%. Please, note I set the throttle trim of the throttle channel to the minimum value, or down value. After completing all the procedures mentioned above, I now was sure the 7C throttle channel was calibrated to the ESC speed input signal.
I was anxious to fly and test the heli after I discovered the mismatching between the Radio System and Blade 400 stock ESC, and fixing such problem as explained above. Needless to say, the lazy and toy like flying Blade 400 now turned to be what it should be, a very powerful, peppy, and agile flyer. No more tail blows in climbing and descends, on flipping, high speed flying, inverted flying, etc.
Summing up, the problems I were having with the heli were because I was reaching full power well before reaching full collective, and after reaching maximum motor speed prematurely, and then still raising the collective, messed things up.
I believe this finding might be happening to many that are using radios other than the stock one, or the ones mentioned and explained in the Blade 400 manual. The radio settings found in the Blade 400 manual have been set to match the stock ESC input signal. But as most of you already know, other brands signals and numbers won't be the same. In other words, the signal output a DX6i, DX7 and JR9303 have at full stick won't be the same as the signal output a Futaba, HiTech or any other brand of radio other than JR or DX will have at maximum throttle setting.
Try the procedure explained above if your heli is acting weird. You might discover you have the same problem I had. Be cautious when separating the motor pinion from the spur: Make sure you do keep it out of the spur and make sure it won't return back to touch it while doing the tests. If the motor engages the spur, you might have an accident or at the least, might damaged the spur.
Thanks for reading and I hope this write up will be of help to many as it was to me.
Try the procedure explained above at your own risk. I shall not be liable for any incident you might have following the procedure I've presented.