Need some help with a stinger 90

[KeithOfAZ]

Recently bought a stinger 90 PNP from motion.
All seemed well until GPS said it was only doing 85mph(plus I could just tell it would sluggish once I hit full throttle for the first time. Heck I could even tell when it was taking off on the first flight.

I have a good amount of EDF experience. Couple freewing 262s, too many 64mm jets to count, every configuration imaginable hunting speed and thrust.

Anyways, I've tried all three timing marks. I've made sure nothing is loose or slipping. When I do a static test, there's no drop in power, but I'm not thrilled with the thrust I'm getting.


Am I expecting too much? Is 85mph, maybe 90mph with a tail wind normal for the 130amp 12blade PNP set up???

I expected more. A lot more.
In the air it feels sluggish. Very similar to the ME262, in fact, my 262 weighs 330g more than my stinger with the same battery, and flies about the same. If the stinger were putting out about 150g more thrust, I think I'd get what I was expecting.


BTW, batteries are mostly 5000mah 50c admirals, broken in and new-ish, and a pulse 65c 4500mah



Thanks for any advice.

[T-CAT]

The Stinger 90 should be around 100mph in stock configuration +/- a few mph. With that said, some GPS's on the market don't fare well in regards to accuracy in an aircraft, while others are better.

So, to ensure you are getting the most out of the stock configuration, be sure that all batteries and the stock motor and ESC are all working well (looks like you checked the batteries already). You may want to use a watt meter as well, but that's up to you. Most importantly, be sure to calibrate the ESC to ensure throttle response makes use of the entire power band. Have you done the ESC's throttle calibration yet?

[KeithOfAZ]

Yes I've done all that, except check the draw with a watt meter. I'll check.

It doesn't have the power of should. Somethings wrong, I can feel it.

My stinger 64 flies circles around this 90.


My GPS unit seems accurate. It was perfect in my truck on the highway, and the speeds it has given me for all my planes seems accurate(judged by my experience, and speed reviews I've read).
GPS asside, the plane makes far less thrust than advertised, and seems sluggish in the air.... Not a trait Id think this plane should have.

[T-CAT]

To be honest, I think Freewing is a bit optimistic on their advertised thrust output. With that said, even with lower than advertised thrust output, if your Stinger 90 is only flying at 85mph consistently in straight and level flight in calm conditions then something isn't quite right, and it may be worth using a watt meter to measure the difference with various batteries, different ESC, etc. to find the source of the problem.

[KeithOfAZ]

If it's not faulty, and this is really all the jet has in the pnp form, then wow. But its not. I know most peoples stinger 90s are faster than mine, but it might not be a broken part, it may be just crappy bearings or something small and stupid like that.

If they won't replace it, 1 I'm upgrading to 8s, and 2 I'm losing hope in this hobby. Why can't an American company start making planes and parts? Why is it so dominated by Chinese manufacturing? Everything is JUNK!

I'm in an industry where quality is everything, and we're held accountable. It's hard to get home from my job and tinker with this Asian made junk.
You can't tell me shipping foam overseas is cheaper than molding it here. And I'll pay twice as much for electronics that actually WORK!

I have a business to run already or I'd start manufacturing RC parts. Maybe one day when I have an entire machine shop(and a bigger building) I'll start making some choice RC parts. I'm sure hiring an American molding company to make a crap load of foam parts to make a plane similar to the stinger 90 would be easy enough. Then pick a great power plant, high quality servos, make our own retracts from 6061 and 7075 aluminum with real dampeners and thick pins\axels. Make a very modular, very powerful, all American made EDF for around $500 PNP.

Maybe one day

[KeithOfAZ]

Checked it again with every battery, and at all timing settings, and the highest I got was around 2550g of thrust. Which is closer to what I figured, and seems about the same as what i got the first time I did the test with a less accurate method of measuring thrust. This test was using an actual spring scale I've tested and made sure is accurate.

[KeithOfAZ]

When throttling up, it makes strange whining sounds where it will change pitch down then back up again while throttling up. Not the constant pitch increase you normally hear. I've flown EDFs for years and never heard this.

anyone have any idea on that? Would it be the motor or ESC?


Thanks for any help.

[Radar-Guy]

When throttling up, it makes strange whining sounds where it will change pitch down then back up again while throttling up. Not the constant pitch increase you normally hear. I've flown EDFs for years and never heard this.

anyone have any idea on that? Would it be the motor or ESC?


Thanks for any help.

I experienced this with a DS 94 HST, the reason was the timing set too low, so try a higher timing again and check your Amp draw. Did you calibrate the throttle settings (set full throttle, connect ESC, etc.)?
I have got one of the early kits and no problems except main retracts that need to be glued to the wing again from time to time. I've added a clear plastic thrust tube to get an exhaust diameter of 75mm and according to my Multiplex GPS the plane tops 200 km/h in shallow dives.

[KeithOfAZ]

Throttle is calibrated. Timing is set to high.

I'm going to get a 150amp high voltage ESC, and see if it changes things.
If not, I'm just going to get an 8 or 10s EDF and cut the crap.

I bought this plane to do 130+, if the stock set up won't reach that then it's coming out anyways.

Maybe motionrc will be kind enough to take the ESC and EDF back for testing. I've spent a few thousand bucks there in the last two years so hopefully they can help me out with this.

[KeithOfAZ]

And are you getting 200kph with the stock set up?
That's more like what I was expecting from all the reviews I've read.

[Radar-Guy]

Yes, I just added the thrusttube and added two thin glass fibre parts to create a wedge in the intake section.

[KeithOfAZ]

I'll try a thrust tube once I get a good powerplant in it.

I tried the plane totally stock at first.

But, I went the opposite direction you did with that wedge. I removed as much of the foam dividing the intakes as possible. I even cut a V into the center of the wing section above the landing gear to allow as much air flow as possible. The wires are zip tied so they won't get sucked into the EDF. It's cleanly done, so I don't think it's causing turbulance or choppy air coming in.

My receiver and gyro are up in the turtle deck, and I removed the LED control box and landing gear sequencing box, to give a very clean battery area. I could even push a second battery back behind where the main battery goes.
I supported the cut ends of the foam in there with thin carbon fiber rods to keep it rigid.
Looking into the intakes, it seems I gave it more breathing room, and the static thrust test seems as high or higher ... But still shy of what it should be. I might be getting 2550g, 2600g of thrust, TOPS.