Head speed?

[Sully16]

Any have thoughts on an ideal head speed for a FBL 450. Running a Turnighy Typhoon 2215H 3550 Kv, Exceed R/C 40A Proton ESC, and 2200 MaH Turnigy Nano-Techs. Runnin a 11T pinion ATM. Had a 12T, but was lost during a crash. But when I put the 11T on the new motor started getting some wobbles. Was thinking about hoppin up to the 13T I have but the head speed calc with my setup is showing close to 3600 RPM. Sounds way to high just curious.

[distractor]

Anywhere in the range of 3000-3500 is fine.
The humble 450 is safe until about 4000rpm.

[satgod]

I have found that 3250 is the sweat spot for me
it performs well even when banging the sticks and battery life is still good

[Andy01]

It depends how you want to fly.

For slow scale circuits around 2500rpm is good. Flights around 8 minutes.
For light 3D and sport flying around 2800rpm is fine. Flights around 6½ minutes.
For hard 3D over 3000rpm is probably where you want to be. Flights around 5 minutes.

IMO 4000rpm is dangerous and asking for something to break, and asking for VERY short flights, probably no more than 3 minutes.

All depends on what you want to do, and how long you want your flights to be.

Assuming a 150T main gear;

3550kV x 11.1V x 0.9 (Efficiency) x 11T / 150T = 2600rpm at 100%.

Even with a 13T pinion, it would be 3073rpm I think you may need a new headspeed calculator.

Colin

[ahunter852]

Hi guys,

Im still kind of new to the hobby so please forgive me if this is a dumb question. but i got a trex 450 Pro V2 (beastx) on its way, and accroding to the heaspeed calulator on readyheli.com ) http://www.readyheli.com/headspeed-calculator.html), with the stock 150t slant main gear,15th helical main drive gear and stock 450MX 3400KV running at 90% effeciency (just a guess coudltn find the actualy efficiency), the max 100% HS is 4007rpm.

to keep it a constant HS like i think you guys are saying do i just run a flat throttle cruve with percentages worked out from its 100%?

so for example in Andy01 post if i wanted to do light 3D/sports flying at 2800rpm, i would run a 70% flat throttle curve? (0-70-70-70-70) is that right??

any help would be great! thanks for your time!

[Andy01]

The 4007rpm is not the right number to look at. It is based on a lipo with around 12.6V, which only happens for a few seconds. They fairly quickly drop down under load to something much lower, and gradually decrease down to around 3.5-3.7V per cell under load.

Hence my calculation above, which is much more realistic and will give you a headspeed of around 3400rpm at 100% (but towards the end of the flight), which is much closer to Mr Mel's end of flight calc.

I would suggest perhaps dropping to a 14T pinion if you are not doing hard 3D - running a low throttle curve and getting the ESC to do the throttling often leads to heat in the ESC.

Also, if you were doing light 3D, you would probably not want to use a Normal curve to do it, so use a Normal curve like 0, 70, 80, 85, 90 etc (depending on your pinion), and Idle Up curve like 90, 85, 80, 85, 90 for flying 3D.

Colin

[paccy]

Originally Posted by ahunter852

Hi guys,

Im still kind of new to the hobby so please forgive me if this is a dumb question. but i got a trex 450 Pro V2 (beastx) on its way, and accroding to the heaspeed calulator on readyheli.com ) http://www.readyheli.com/headspeed-calculator.html), with the stock 150t slant main gear,15th helical main drive gear and stock 450MX 3400KV running at 90% effeciency (just a guess coudltn find the actualy efficiency), the max 100% HS is 4007rpm.

to keep it a constant HS like i think you guys are saying do i just run a flat throttle cruve with percentages worked out from its 100%?

so for example in Andy01 post if i wanted to do light 3D/sports flying at 2800rpm, i would run a 70% flat throttle curve? (0-70-70-70-70) is that right??

any help would be great! thanks for your time!

The stock slant main gear is 121t, not 150. I would run an 11t pinion at around 90% flat to get 2800ish.

[youturnjason]

FBL likes higher headspeed, otherwise it can feel mushy on the collective. I don't fly hard 3d but i like having a bit of 'pop' on collective. Found 3100-3300 to be the sweet spot. Normally fly for 5 minutes and only put back about 70% in the lipo.

[ahunter852]

thanks for the info guys,

but am i right in thinking that if i keep the stock gearing, (15/121) and run it at a lower thorttle % i can get a long flight time? because the motor doesnt need to spin at max to get a good HS.

thanks!

[youturnjason]

Will extend it a little, but changing the gearing will extend alot more, as the motor doesn't have to work as hard, also brushless motors tend to run most efficiently at 100% throttle.

[Andy01]

Originally Posted by ahunter852

thanks for the info guys,

but am i right in thinking that if i keep the stock gearing, (15/121) and run it at a lower thorttle % i can get a long flight time? because the motor doesnt need to spin at max to get a good HS.

thanks!

Well, with that combo;

3550 x 11.1 x 0.9 x 15T / 121T = 4400rpm

So, yes you would want to run quite a lot slower than that I would think (like about 65%) - your flight time at 4400rpm would be quite short I would suspect, and youy would want to have a set of quality blades at that speed. The problem is doing that with the ESC is quite likely to cause (heat) problems with the ESC, unless it is a Kontronics.

A much smaller pinion would be what I would recommend - try 11T, and then throttle a bit further with the ESC.

Colin

[youturnjason]

I'd count the number of teeth on your pinion. If its stock align its either 11 or 12t they dont make a 15t helical as far as i know.