Hi all, I posted this on another site but I only hear crickets in that thread. - This is for a 4 blade 450 A109, I'm going to add a 4 blade tail soon -
I just found a speed calculator that came with the Hobby Wing program box. It's saying for 2300 HS (which is around where multi-blade scales should be I think - PLEASE someone correct me if I'm wrong) I should be using a 9T pinion instead of a 12T with the 3s batteries and 3500KV motor I'm using. I will change it when my castle creations capacitor pack comes in that I'm going to use on the extended battery wires I added. The smaller pinion with resulting lower head speed should allow the motor to run at a higher rmp which in turn should be more efficient with longer flight/battery time... Can somebody tell me if I have this right? Thanks for any help. Tim

I'll post this over here too-
Just wanted to say thanks to the people involved in the past DIY 4 blade tail threads - Super-Hornet, BlackTitanium, FerretMaster and to KevinMc for guiding me to them. And anyone else involved with the threads.
Here are a couple I remembered to save in my favorites - http://www.helifreak.com/showthread....hlight=kevinmc
http://rc.runryder.com/helicopter/t392402p1/

I used an Mcpx titanium main shaft I had and FerretMasters way of attaching the links to the slider to get the tail rotors closer together. I also put bushings from broken main blade roots inbetween the ball links and the slider to get the link more straight. I haven't tried it out yet but it all slides and changes pitch nicely. I'm sure the pitch will need to be adjusted on the links. It spins up great on a drill chuck .

You must not use 2 blade performance for 4 blade they are not the same, your motor wont handle it. u need a larger pinion not a smaller one ..having a target headspeed in OUR HELIS is not done on paper but on a hover,, the biggest hurdle is how your tail will handle the torque ,,your headspeed will be based on that.

Wow! Only the first line of your statement is correct nuscale. Tim, you are exactly right in your assessment, but with no experience of 450 size scale I cant advise on the 9 or 12 tooth pinion. Going to a 9 tooth pinion will reduce the headpeed by 25% but your motor will run at the same rpm. If that is in the range of maximum efficiency, then that's the way to go. The load on the motor will increase due to the extra 2 blades, but will reduce due to the lowered gearing.

Having done that, you then adjust the size and number of tail blades to keep the tail in order!

If you cant get sufficient tail control then you start to fine tune the head speed and also the type of main blades to make the tail work. It's the last part of the equation, not the first.

Peter Wales
http://scalehelicopters.org

Ok thank you Peter for confirming that. It actually is flying very well how it is now. I was just wondering what I could do to get longer flight times with the batteries I have. If the rpm will stay the same if I lower the pinion size couldn't I just lower the collective pitch and keep the pinion I have on there now to get the rpm up? It's my understanding that most of the flying should be done in the upper rpm range of the motor to maximize efficiency and get longer flight time. So is it as simple as get the rmp up - get longer flight time? Or are you saying I should go to a smaller pinion to reduce the load also? If it's possible to gauge load by how much power the heli "seems" to have in flight I don't think it's an issue because there's plenty of power, nowhere near bogging with the kind of flying I do with this heli. But I may have that conception all wrong. Any opinions or suggestions are appreciated.
I'm getting 5.5 minutes now, seems kind of low to me but then again this heli is pretty heavy with the 3 retract servos and some added fiberglassing I did. I'm using GA 3s 4000mAh batteries with an Align 450M and HW Platinum Pro 60A esc with the timing set to (whatever the specs say for the Align450M I forget now). I'de like to stick with these batteries because I think I'm at a point where anything heavier would be counter productive and they fit perfectly where I get good CG. Plus I just ordered two more because they were on sale.

Slowing the head down will dramatically reduce the drag and thus increase your flight times. Most motors want to run at 80%+ throttle for maximum efficiency.

Putting these 2 factors together you alter your gearing to get the low headspeed and high motor speed for maximum duration.

I am working on a Goblin for a scale application and some of the 3D whizz kids are getting 3 minutes duration at 2300 rpm. I am getting 12 minutes from a 4 blade setup at 1500 rpm using the same size batteries.

Peter Wales
http://scalehelicopters.org

Good info. My 4 blade mechs running at 1300 rpm HS with 600mm blades is getting great flight times. I landed after an 8 minute flight and only put 2300mah back into my 5000mah 6S. They go a long way when you slow down the HS and run the motor in the efficient range.
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

Gotcha, thanks guys. I have it all apart now, going to change the pinion and install the Castle capacitor pack for the extended esc battery wires I added. I think I'll test it out as a pod and boom with a weight = to the fuse and might as well try out that 4 blade tail I made. Thanks again for the help.

wow peter wales. correcting me then repeating what i just said ,about headspeed tuning due to increased torque ,,450 size helis require faster headspeeds .
unlike large high end ones and not much selection on blade types ,,,my 2 cents was based on a PRACTICAL application based on 450 parts available ,,,i have a 5 blade 450 size flying well.. i have done the actual trial and errors,and know what actually works on a 450 size and Not the regular Efficiency, Drag ,Plate mass blah blah you read out there.
on large scale helis like vario very different
K.I.S.S. METHOD.is BEST its not rocket science..just fun.

You are definitley right about 450 parts availabilty for scale. I couldn't find 450 scale suspension struts anywhere, had to get some airplane landing gear. They just came today but as I thought they would be they are too long. Maybe I can cut them down without destroying the spring inside somehow.
Next problem is I have a whole box of every tooth size pinion but they are all 3.17mm shaft. I can't find a tooth count smaller than 11T for the Align 450M 3.5mm shaft. Any suggestions where to look? Thanks, Tim

tim
heres my K.I.S.S. method
1. start by adding 2t (minimum) to the current pinion u are using on 2 blades
2.make sure your batts are healthy and have a C Rating of 40 or more
3 try to get the old 315mm blades align used to make.(STAY AWAY FROM the 325mm)
4 make sure your MAX pitch is no more than 6-7 dergrees
5. midstick is 3-4 degrees
6. adjust midstick power starting at 65% until you get best hover with good tail hold.
now fly tim fly !!
>>> as far as scale details ..u will need to make ur own.
stay blah blah free my friend

Ok thanks, that's just about the same advise I got from doing some other reading.

Increasing the pinion size will increase the head speed. It is normal to reduce the head speed when going from 2 blades to 4 blades.

Increasing the head speed will increase the drag, regardless of pitch. This reduces flight time.

When I am changing from 2 to 4 blades, I start by defining the head speed I want to run 5 degrees of pitch at hover and 9 degrees at full pitch. I have to bear in mind the maximum head speed the head manufacturer has stated about the head and blades I intend to use. Then I select the pinion needed to run the motor at about 80% throttle to achieve this.

Thats my way of doing it and I get long flight times.

Your way of doing it increases the headspeed, runs lower hover pitch and lower maximum pitch, I presume to get tail authority. What ever your way uses a lot more power to drive the head faster. I prefer to design the tail system to suit the rest of the heli rather than simply wind it up and suck the batteries flat.

This can be done by using more tail blades, bigger tail blades, wider tail blades or speeding up the tail by altering gears or pulleys. As I said, I have no experience of 450 scale so my advice cannot be specific, but your response goes against my way of doing things and the end result is Tim is complaining of the problem I try to avoid.

I am sure your way works, but it has a severe downside in power consumption, but, as they say, there is more than one way to skin a cat.

Peter Wales
http://scalehelicopters.org

I don't often listen to advice, but when I do - I listen to Peter Wales

(Apart from skinning cats which I find offensive.)

I have a Blade 400 "detuned" for scale practice in my back yard. Among other things it uses a 2608 kv motor to allow me to run at ~1950 with high throttle%. The blades are the old 325 Aligns and it has a ZYX FBL controller on it.

To quote a good friend "this flies like a much bigger heli". It will also fly for a very long time and the motor stays cold.

If I was going multi blade I would probably drop the head speed even more or make narrower chord blades. I suspect a slight increase in tail blade length would address any tail power issues.

Yeah, I assumed nuscale meant decrease pinion size by 2 teeth not add.

yes i mean ADD 2t to current pinion on 2 blade setup.
hey why not use the smallest pinion u can get in any setup that way u get the highest headspeed and longest flight time?. isn that what teamdavey and peterwales is saying?? .thats also wrong!!

>> Imagine riding a bicycle ( with gears) on a flat road. ( 2 blade),
on a given gear ,,now u have to go uphill ( 4 blade) more load,,
do u increase or decrease REar sprocket size (pinion)? looks good on paper BUTT , your motor esc batt will be unable to do the task.

>> what does your car do on a uphill? it downshifts (larger pinion) ..creating more torque ..and preventing damage..overheating etc. DOES YOUR mph(headpeed) change?..peak horspower change?

although peter wales ideas are good they are not applicable to 450 size.. speed up gears? and blade type n sizes? ( not available) its NOT VARIO or hey ",make ur own blades"... thats practical right.?
its a 450 !!! ...lower headspeeds will make it unstable and sluggish at best..

y not u do u own experiment? and tell us.here.. and watch for bladespeed decay ( falling off the sky).when that happens your small pinion wont get u out of it.batts will puff too.stripped main gear,etc..etc..
>>u can lower ur pinion but will need to increase voltage to 4s or 5S..or go Nitro on a 450,,Since " MAKING UR OWN Narrow chord BLADES" IS AN ADVICE GIVEN ,,practical right?

Y not CONVERT UR 450 TO A VARIO turbine..That will work.too much easier than "making ur own blades" or finding parts that are non existent
>> give it a K.I.S.S.. stay blah blah free

I'm using 4 scale blades bought from the classifieds on another site. He painted and balanced them but I'm pretty sure he didn't make them himself.

Sorry Nu, but I'll also go with Peter on this one.

Lower head speed will give better performance on a scale bird. Doesn't matter if its a big vario or a little 450.

I'd start at a 80 reduction from a sport models HS for a 4 bladed 450 and go from there.

Problem is usually finding pinions to get that HS (unless you change motors KVs)

Les

NuScale, I hate to tell you, but you've got it backwards. If you need more TQ, you add teeth to the driven gear (main gear), or reduce the number of drive teeth (pinion). It's the same in a car, no difference.

On a bike: you decrease the front drive gear (pinion) and increase the rear driven gear (main gear) for more TQ to climb a hill. This increases the number of peddle revolutions required to travel the same distance, but increases the available TQ to drive the rear wheel. So you peddle more, but exert less overall effort.

Example: My racecar is falling on it's face with a 3.73:1 gear ratio in the rearend. At 3.73:1 the driveshaft turns 3.73 complete revolutions for 1 full revolution of the ring gear. I then bump that number up to 4.56:1 and the driveshaft turns 4.56 turns for a full revolution of the ring gear. This enables the engine to do less work and apply more TQ to the rear wheels. It's the same in a heli, when you let the motor spin at it's most efficient rpm per volt, the motor doesn't work as hard and consumes less energy per minute of flight time.

So you work the gear ratio, voltage and KV numbers to a point where you find the sweet spot and you are consuming less energy. Now do the same thing, but slow the rotor head speed down and you get longer flight times. I can tell you first hand that this is true, because I have tested in in 2 of my scale test mules. High head speed consumes more power.
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

no MOJAVE ITS you that has it upside down.
>> your race car terms USELESS BECAUSE THEY are based ON motors / powerplants that CAN DO THE WORK.
NOT stock in any way . I AM REFERING TO USING the same MOTOR.ESC BATT COMBO..and MAKING IT WORK HARDER BY adding 2 more blades....
by using smaller pinion ..U PUFF THE BATT GET ESC HOT..ETC..
its FUNNy when i RACED CARS years ago. i always Downshifted (larger pinion) if needed more torque to get out of the turn NOT UPSHIFT )(SMALLER PINION) AND i also never took off on 6th gear (small pinion.)
i have been wating for tim.. to tell us what he found out.
motor RPM has to be UP ,, Headspeed down..
YES IT will use more power BECAUSE IT NEEDS IT.. same as UPGRADING TO a motor with MORE HORSPOWER.
if U WANT TO use less POWER consumption..LIGHTEN THE TOTAL RAMP WEIGHT.
Revolutions.ratios..more blah blah blah. im still waiting for tim to tell us what happened with his 4 blade 450.