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Old Nov 24, 2011, 02:04 AM
teamwork, do it my way!
Dubai, UAE
Joined Jun 2007
717 Posts
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Motor Recommendations - 450 Scale Ships

Hey All,

I have been scouring the forums (here and elswhere) to try and get the best combo for some scale flight, long flight times and general efficiency.
I am hoping someone can advise on my needs..

First, I am using the following.
HK 450
Turnigy Plush 40A ESC - using the on board BEC but will change to external so I can run a light kit too.
TP2415-09T Motor that is rated at 2700kV
11T pinion
MD500 Fuse
Zippy/Flightmax 3S 2200mah battery
Flight times: Approx 7 mins ave leaving 20% headroom on battery use
ESC is warm at shutdown, but not hot. I expect this to improve more with the external BEC.
Blades are currently HK 335mm blades but am going to upgrade to FBL 4 blade head and scale blades.
Not sure on the current headspeed, but I am prettysure it is higher than I need for this application.

I am also running the same setup in another heli, the only differences being that this one has a Huey fuse, with HK FBL head conversion and Beastx, and the blades are the scaleflying Huey assymetricals.

The latter one has not been flown in the fuse yet, I am still testing it for flight characteristics and I need to improve the tail drive. I am ordering the HK lifted tail setup in one of the other threads.

Now, what I am after.
6 min flight times at the moment are fine for me. I am a novice pilot and all I want to do is fly scale patterns, with no stunts and such. I would like to improve flight times by as much as I can. I understand that reducing headspeed is going to be the 'easiest' way to do this, andwith a lower Kv motor I could then play with pinion sizes to achieve what I need. With the FBL unit I expect that with less resistance without the paddles I should get better flight times, but I think I can do better.
I would like to get a motor that is around the 2100Kv mark and work from there. I am also hoping to change the ESC to a lower rating one, considering that I will be using an external BEC, I could change to an OPTO type, and maybe get away with a lighter 30A or 25A unit.
I also know that reducing HS will result in loss in tail authority, and I will try to counteract this with larger tail blades, and failing that will look to increasing tail speed.

On the MD500, when I upgrade to the 4 blade head, I will also consider upgrading the tail unit to a 4 blade unit.

I appreciate any feedback, and I shop at Hobbyking a lot because they are reliable with deliveries to the UAE so would prefer recommendations from them.

Thank you for listening to my rambling.....
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Old Nov 24, 2011, 03:39 AM
Complete RC Idiot Savant
The Netherlands
Joined Nov 2009
2,969 Posts
Don't try increasing headspeed. Instead, try modifying the mainblades for an E-flite blade mCP X.... shorten them to 52 mm (from centre hole to tip) and reduce if necessary. You will have great tail authority even with headspeeds below 2000 RPM, and high-drag mainblades like the Copter-X/SM blades and a fourbladed head. Power consumption from the tail will also drop noticeable

Another trick to get more out of your rotor, is to increase rotordiameter. I am using a Copter-X rigid head with extension bushings, adding 10 mm to each blade grip, thus increasing rotor diameter with 20 mm, and this is very noticeable in flying characteristics (I am flying without any electronic stabilisation) and reduces disc-load. Because of this you can lower headspeed without negative effects and this will help you save some power too....

With a cheap-ass 3500 kV motor and 10T pinion I get an easy 7.5 minutes from a 2600 mAh pack, with approx 30% charge to spare

I am using Spinblade semi symetrical 350 mm blades in combination with these extension bushings, giving a rotordiameter of 790 mm on 1.2 kilo TOW.
This results in a helicopter that is flyable up to 3~4 Bft (with the necessary piloting skils of course).

With stabilisation, it should be a "walk in the park" as mr Maverick put it....

Brgds, Bert
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Old Nov 24, 2011, 05:57 AM
teamwork, do it my way!
Dubai, UAE
Joined Jun 2007
717 Posts
Brutus,

Thanks for the comments, I have read about your flying without e-stab, and for sure I would like to be able to do that....but it will take time.

Your first comment "dont increase head speed" ...can I assume you meant tail speed?
I will pick up some MCPx mains this afternoon....are they easy to cut without splintering/breaking?

With regards to the motor, I saw a Turnigy H2218-2100Kv motor which I will order later and try..probably on a 13T pinion and see what sort of speeds I am getting. I will try it on the MD500 with the 3D symmetrical baldes. I use this as my test bed because it is VERY stable as a flyer, and pretty chunky too so it is a good 'lift' test.
I hear you on the rotor diameter, but in contrast to what you have said, I get better flight times out of the 325mm blades that I do from the 335's. Not sure why but logic (mine) dictates that the motor needs to swing a bigger disc....more power?
On 335's I get the 7mins flight I spoke of earlier. On the 325's I get at least another minute..go figure. In both cases, I am normally putting 1500Mah back into them, so weill in the limits of the batteries.
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Old Nov 24, 2011, 04:06 PM
Complete RC Idiot Savant
The Netherlands
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Nope.... I meant, don't increase headspeed in order to have a higher tail RPM as a side effect. But don't change the gearing of the tail for a higher tail RPM as well.... you will gain tail authority but also loose flight time and load up the drive train more. Just modify the tail with bigger or better tailblades.

In general, most people are flying with way too high headspeeds anyway.
I see a lot of multiblades being run at 2500+ RPM. So far, the highest I needed has been 2200 RPM, and at the moment I am running estimated well below 2000 RPM.

EDIT: Most blades can handle higher headspeeds (My Spinblades are rated for 2600 RPM max) but in my experience, steering and handling does not improve with higher headspeeds, most likely due the fact that increased headspeed also meand increased cyclic frequency and the blades resist more to this at higher speeds. I do not know this for sure, but the fact is, that with increasing headspeeds, I noticed a slight gain in stability but a bigger deterioration in cyclic response, with the result that handling is better at lower headspeeds

It should be kept in mind, that a bog standard 450 will fly perfectly well with approx 2000 RPM headspeed. It is 3D flying that requires the high headspeeds, just because then you are doing things a helicopter should not be able to do in the first place. One of those is keeping the mainblades above stall speed, another is to keep tail authority in these extreme conditions.
But when modifying a 450 to multiblade, you are exposing the standard tailrotor system (rotor including drivetrain and linkage) to a workload it was never intended for. So it is better to modify the tailrotor with either bigger blades or more blades, what ever suits your needs better./EDIT

The mCP X mainblades are just plastic and can be trimmed with whatever you like. I just used scissors for the rough trimming, and sandpaper for final squaring off of the tips and balancing.

If you are running symetrical 3D type blades, it makes sense that longer blades will cost flight time. Symetrical blades are not very efficient where it comes to generating lift, but they are pretty good at generating drag and loading up the tail rotor (compared to semi symetrical, of course). The difference is that I did not use longer blades, but just placed the existing blades a little more out....

If you are increasing rotordiameter, it is of course necessary to reduce headspeed. Pretty much reduce just in order to keep the same tipspeed, and power consumption will be approximately the same but with better lifitng capabilities. Even when you use the same blades and extend only the blade grips, effectively not changing anything on the actual aerofoil but just increasing swept surface (like I did at first). the trick is, when using the exact same blades but on a larger diameter, and keeping the tipspeed constant, the speed distribution over the length of the blades improves towards the hub and even if it seems not much, a relative larger part of the blade is actually involved in creating lift, and a lesser part of the blade is just only creating drag. That goes for both semi and full symetric. On semi, the ratio is just even better.... Because of this, you need less angle of attack at the same bladespeed, and thus power consumption is with a little luck, decreasing. Actually it is pretty logical: if you improve rotor efficiency, and need to create the same lift with it, it is natural that power required is less


I was using "carbonhobby" 325 blades at first (disc diameter 720 mm), and got approx 5 minutes of safe flight time. with the extended bladegrips (740 mm) and adjusted headspeed I got better flying and handling characteristics, with an increase in flight time of approx 45 sec as a bonus. Now I am running Spinblades 350 mm semi symetric on extended bladegrips (790 mm) and get 7 minutes on the same batteries. Flying and handling have improved dramatically (but still it is a rigid, so it is not an easy machine to pilot)

Brgds, Bert
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Last edited by Brutus1967; Nov 25, 2011 at 05:36 AM.
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Old Nov 26, 2011, 02:50 PM
3D and Scale RC Heli Pilot
BlackTitanium's Avatar
Monroe, WA
Joined Jan 2007
836 Posts
That's a great tip Bert!
I'll try the mCP X tail mod on my Apache. Even with a 4 blade tail, I still need more tail authority.
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Old Nov 27, 2011, 01:59 AM
teamwork, do it my way!
Dubai, UAE
Joined Jun 2007
717 Posts
I acquired a pair of MCPX baldes yesterday. I notice that the std blades have that 'bullet" looking weight thingy on it, so I wen for the performance blades.At a glance I can see how much wider the chord is from an average tail blade, they look like they will do the trick for sure.

I also ordered the Turnigy H2218-2100Kv yesterday, which is 600KV less than what I am runnning now, so will certainly bring the headspeed down...
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Old Nov 27, 2011, 10:29 AM
Complete RC Idiot Savant
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Oops, silly me! Of course, I meant the mCPx blades without the "bullet thingies" on them.

It is not only a matter of wider chord, but also a matter of thinner profile.
The mCPx blades have been designed for a rotational speed of approx 4000 RPM at their original diameter. When cutting them to approx 52 mm and using them as tail blades, you are exposing the airfoil to approx the same airspeed as it was intended for.

Positive side-effect is that the surface is smoother than most plastic tail blades, which reduces drag. This together with the lower required angle of incidence makes for a lower power consumption of the tail, and this is a nice little bonus in extra flight time.

There is a downside as well: they more or less hate larger pitch deflections (lots of power needed for the tail, with only small thrust increase at these large angles) so you have to adjust the throw of the tail slider accordingly. Just take a little care when adjusting and you will have a tail that will make you smile every time you spool up and take off.

Brgds, Bert
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Old Nov 27, 2011, 10:31 AM
Complete RC Idiot Savant
The Netherlands
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Quote:
Originally Posted by BlackTitanium View Post
That's a great tip Bert!
I'll try the mCP X tail mod on my Apache. Even with a 4 blade tail, I still need more tail authority.
maybe it is wise, to start with a two bladed tail and the mCPx-mod for starters....

Brgds, Bert
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Old Nov 27, 2011, 11:18 AM
teamwork, do it my way!
Dubai, UAE
Joined Jun 2007
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Quote:
Originally Posted by Brutus1967 View Post

There is a downside as well: they more or less hate larger pitch deflections (lots of power needed for the tail, with only small thrust increase at these large angles) so you have to adjust the throw of the tail slider accordingly. Just take a little care when adjusting and you will have a tail that will make you smile every time you spool up and take off.

Brgds, Bert
Urgh....my MD500 is buried in the fuse, not easy to get to at all. I am thinking of cutting a hatch above the gyro for adjustments. I cannot reduce the pitch without doing so. What I might do as a temp is to dial in some more expo on the rudder....I am not pirouetting this thing so I will try the expo first...
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Old Nov 27, 2011, 12:50 PM
3D and Scale RC Heli Pilot
BlackTitanium's Avatar
Monroe, WA
Joined Jan 2007
836 Posts
Quote:
Originally Posted by Cathurga View Post
Urgh....my MD500 is buried in the fuse, not easy to get to at all. I am thinking of cutting a hatch above the gyro for adjustments. I cannot reduce the pitch without doing so. What I might do as a temp is to dial in some more expo on the rudder....I am not pirouetting this thing so I will try the expo first...
Mount the Gyro, in the front of the fuselage:





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Old Nov 27, 2011, 01:07 PM
Complete RC Idiot Savant
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@ Cathurga:

If you are using rate mode, you can better reduce EPA than use expo.
If you are using heading hold, you need to either reduce the limits (unfortunately that is located on the gyro) or use one size smaller servo arm/disc.

@ Black Titanium: Am I seeing that right? 3 different BO 105es? keeewwwllll!

Brgds, Bert
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Old Nov 27, 2011, 01:22 PM
3D and Scale RC Heli Pilot
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Monroe, WA
Joined Jan 2007
836 Posts
The yellow 450 size BO-105, was a review build I did for HeliArtist.
And was also a demonstration of a low budget build, using all Hobby King parts, withe exception of the JR Gyro.

The 450 size aerobatic Red Bull BO-105, crashed due to on looker distraction and pilot error, performing a loop too low and couldn't bail out.

The 500 size Military BO-105, crashed due to loss of orientation, in heavy shadow and below tree line. The camouflage worked too well!

I now only have one 500 size BO-105.

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Old Nov 27, 2011, 01:49 PM
Complete RC Idiot Savant
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Yep, that Camo paint can be tricky, couple of years back I nearly lost my Japanese camo painted Cobr when flying below the tree line too....

Brgds, Bert
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Old Dec 08, 2011, 04:58 PM
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New Zealand, Canterbury, Temuka
Joined May 2011
177 Posts
flight times

my HK450 setup (pod n boom)
typhoon 2215 with 13 tooth
2200 3s zippy
=
12 min flight time (scale flying)

450 (huey 212 fuse)
typhoon 2215 with 13 tooth
3000 3s (for weight in front)
= 10 min flight time (scale flight)

450 TT (MD500)
typhoon 2215 13 tooth
3000 4s (for weight balance)
11 mins flight (scale flight)
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Old Dec 24, 2011, 05:54 AM
teamwork, do it my way!
Dubai, UAE
Joined Jun 2007
717 Posts
Installed the 2100Kv motor, and after 8mins of low impact (read hovering) I had to put 1200Mah back into my 2200Mah batteries. By that, I figure 12-13 min flight times will be possible.

I am running a 11t pinion, but my speed gun was flat battery so couldnt get actual hs...

I am happy with this setup, but as it is being tested in Pod n boom before I get it in the fuse, I will most certainly not get that time IN the fuse.
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