Scale Spool Blues?

[georgi UK]

=] "something" that is missing on a scale build flight video, is the lack of realism on starting up. So, in my usual determined way went about board blasting ideas on how to achieve this, mostly mechanically as this is my area of expertise.

but really why add "something" when we have an ESC that can be flashed to give the desired results?

Phew! that was a very bad decision, I thought expert HF guys shared my same inspiration when assisting "lost souls" like me? obviously not! they prefer to be experts and that's it....

So, here I am still trying to figure this one out, you guys know of that "something" to help me achieve this? Thanks!

[Andy01]

Georgi

Are you referring to a slow scale spool-up, and if so, how slow do you want to go ?

Personally I just use the slowest setting on my CC Ice/Edge ESCs, and get about 30-40 seconds, but for any more realistic than this, you probably need to include a clutch into the drive train - it gives you the whine when the motor starts without the blades turning yet.

Colin

[georgi UK]

=] Colin hi!

I had a fortunate event the other week when an Air Ambulance A-119 landed a few hundred yards from my home, (no-one was taken away in it!) least to say I hung around for the departure, very impressive!

Yes a clutch would really help me out here, but for a 450 is there really such an animal? Thanks!

[Keyrigger]

I have not heard of a clutch system in a 450 size so far. Bringing up the collective stick very slowly in Normal mode might be the easiest way to do it and even then, the point that the motor is engaged by the ESC might already whip it up to 500rpm. In the Castle ESC's there is a setting for power at start-up, that you could lower so the motor does not start it's spool-up as hard. One thing to keep in mind, though. What ever settings you have for start-up will apply every time the ESC reaches the shut-off point. If you inadvertently hit low throttle while doing maneuvers in Normal mode (I have done this), the resulting slow spool-up can allow the helicopter to fall out of the sky before the spool-up has finished. At that point, you pray you have enough altitude to recover. Hope this helps.

Don

[georgi UK]

=] Don hi! To explain further, I'm running in external gov mode, this means a handover once the RPM's are getting there, at that point it's locked and won't re-enter re-spool mode unless I hit TH or flick out of idle1 but I take your point, thanks!

As for Colin's suggestion it may need an intermediate clutch between the motor and pinion??!

[goodhunting]

Just be careful with the pitch setting at this point where you are building up speed/RPM... At about 0 degrees the helicopter tends to get in the ground resonance stage where it can destroy itself. Plenty of videos on YT both of models and real things. So if you're going for that make sure that you build up speed in the positive pitch range just below the "magical" 5.5 degrees...

Gh

[Andy01]

Georgi

The clutches tended to be on older 50 or 600 size nitro machines, which would be massive for a 450. I think it would be a real challenge to mod the mechanics to get one in.

I would suggest running a CC Edge 50 in Set RPM mode and set the power to Low, the Rate of change of headspeed to Low, and the soft start to 0. This should give you a fairly progressive spool up over about 40 seconds. If you are running around 2000-2300rpm (depends how many blades), it should sound reasonable.

But no scale 450 size with a headspeed of over 2000rpm will ever replicate the spool up of a 4 blade full size with a headspeed of probably around 300-400rpm . It just needs to sound more scale than a 450 3D blaster going from 0 - 4200rpm in 0.5 seconds

Colin

[ERRATIC]

Originally Posted by Andy01

I would suggest running a CC Edge 50 in Set RPM mode and set the power to Low, the Rate of change of headspeed to Low, and the soft start to 0. This should give you a fairly progressive spool up over about 40 seconds. If you are running around 2000-2300rpm (depends how many blades), it should sound reasonable.
Colin

+1

Adding a sound card may enhance the effect also. Turn on the engine sound before spool up.

Steve

[georgi UK]

=] latest thinking thanks to Colin! small nitro buggy clutch, that has got to be small?

[heli143]

I've converted several of my helicopters from nitro to electric and intoduced a clutch system. I have done 30/50 and 90 size helis.
I purchased a prop adaptor which would attach to the motor shaft and the clutch would then screw on to the adaptor.
I know the prop adaptors come in different sizes and I'm sure they must have a prop dadaptor in the .25-.28 size which may be a fit for a 450 size engine (Just a guess at this point without my researching it further)

I have two 450 size nitro helicopters in the shop and I may experiment with one of them just to find out

[georgi UK]

=] well, I'm making steady progress! I'm hoping the 5 bladed head will slow things down even more, plus the tail component drag also? should find that out later this week!

Hard to tell in the vid, but it's a 70 sec spool from a standing start, so it's prob around 70% there when I shut it down and go again. this is using a linear non-gov throttle. there is no input from me during the spool, I'm simply the camera guy!

Turbine Start..... (2 min 43 sec)

[Keyrigger]

I'd say you have it. It looks slow enough to pass as a much larger helicopter model spooling up. Remember to keep your pitch slightly positive as you spool up to keep those resonant vibrations at bay. Take care.

Don

[georgi UK]

=] YT quality isn't really that representative (makes it look faster?) but I'm getting good results now, and will be fitting the 5 blade head and tail to apply the full loads, see what you guys think??!

#3 HEX (2 min 1 sec)

Thanks!

[Keyrigger]

It looks great to me, but what do I know, lol. Don't change a thing as you have got a great looking spool-up. When you get the entire project finished, a lot of guys will take notice that you have done something really cool with your spool-up speed. Take care.

Don