CCPM Vs HPM

[Steve]

My flying mate has 2 Sceadu 50s, one CCPM, and one HPM.

One has a 601 gyro, the other has a 611 gyro. Both have the same carbon upgrades like head dampers, flybar stiffners, extra cooling ducts, fins and the same fancy carbon blades. Both have the same high torque, high speed coreless servos on the cyclic controls. One has an OS50 Hyper engine, the other has a normal OS50 engine. Both have Muscle Pipes.

He likes to throw his helicopters around the sky in a 3D stylie.

When pushed as to which one is better, he just can't make his mind up as they are so similar, which begs 2 questions;

1. Is the Hyper engine worth the extra cost?

2. Is CCPM better or worse than HPM?

Of course there's more than one way to crack an egg, or indeed solve an engineering problem which probably answers the 2nd question, but maybe you have other views?

[Raptorite]

There are pros and cons of each of the two control types, I personally prefer the normal layout of 1 servo to 1 function rather than a ccpm setup which generally has 3 servos working together to give the 3 controls of aileron, elevator and pitch. Although if you flew models back to back with the two different control types, Im sure there wouldnt be that much of a noticable difference, maybe the pitch is a bit more powerful on the ccpm setup, but that would be about it.

As far as the engine goes, the only difference between the 50sxh and the hyper is the head and the carb, the rest of the engine is identical between the two. A quick glance at the parts list will confirm this. So for the extra money for the hyper, you are really only getting a larger bore carb, which means more fuel gets into the engine quicker, and a bigger head, which means there is more space in the combustion chamber for a bigger bang.

At the moment I run the standard 50sxh in my 2 50's, so I couldnt tell you how much more grunt you can expect out of a hyper, but like all engines that is very dependant on the fuel/plug/exhaust you run.

Cheers,
Pete.

[Ade_Law]

There certainly is a good amount of power difference between the 2 motors and the hyper carb doesnt need the cateye mod to cure the lean spot. And seems to run smoother. Especially on an MP2 or Hatori muffler.

the sceadu evo 50 mechanical mix is one of the best available. Its Pushpull on all controls making it very accurate with a good stiff collective arn.

With CCPM if you have a modern radio like the 9c or 9x (or better) then you will have no problems with CCPM. Lesser radios suffer from the channel 6 servo lagging during fast movements. This causes interactions in stuff like tic tocs.

with CCPM it only uses about 60% of the servos travel for each control So you need to use good quality servos. Minimum of 3152 or 811s.

having said that i wouldnt recomend using less than that on any heli. Difference is you can get away with using only 1 3152 and the cyclic servos can be just 3001s

The other problem people have is interaction due to bad setup. If you dont get those servos 90 degs to the pushrods at centre stick with no sub trim you are going to be in for some trouble.

The reason for the lack of sub trim is that you are using more than 100% of the servos travel any sub trim will cause the servo to "stop" early when using full collective and cyclic which will give very strange results.

if you dont get them spot on 90degs then the swash will not be flat through the entire collective range.

now... once you get the CCPM setup right with good servos. You have an advantage of the load being shared equally accross the servos. But your only using half the servos range so effectively doubles the servos speed!

which is why CCPM helis tend to have quick cyclic and collective.

i personally think CCPM does fly better, now i have owned a heli with CCPM for 9 months. You just have to spend a bit more time getting the setup right.

Ade

[G-DAVE]

The OS 50 argument --- Had plain 50's in the past and was always fiddling with the carb. put a hyper in my Sylphide and hav'nt had to touch it since the intial set-up.

ccpm is the way to go -- had mixed opinions for a while then saw an American video showing in detail the setting up of an X-cell Fury which is of course ccpm, once you know the trick it's no problem to set up.

Dave

[Steve]

True, CCPM uses much less servo travel, but at the expense of a longer servo arm, so it's benefits are surely cancelled out.

I'm quickly learning the art of setting up a CCPM heli accurately and have spent much time over the last week or so fiddling with my JR Voyager, trying (and succeeding!) to get 0 deg pitch (with a dead flat swash plate) at mid stick, when the pitch curve is at 0% with it's limits at +100% and -100%

I'm learning fast, but the results are my very accurate 30 sized heli becoming even more accurate!

I used to use the servo end points to set my +10 deg and -10 deg pitch limits, but if (for example) this requires +120% and -90% on the Tx, then the middle is not at 0%.... all the various setting interact with each other, so I've deduced that the answer is to set the pitch control limits to +100% and -100%, then mechanically make sure I've got 0 deg pitch at mid stick with the servos at 90 degress to the push rods and the swash plate level with zero trim and zero sub trims or centres. This seems to make good engineering sense.

I have then used the pitch curves to get the desired maximum and minimum pitch settings, working from the centre outwards, even if that means using settings like 120% or 86% (as an example) to get +10 deg - at least I know that my base reference point is 0 deg at mid stick, and then build my curves around that.

It's taken quite a bit more thought than a HPM setup, but the results seem good so far.

Gone off the topic a bit here....... but is there some truth in the fist paragraph?