O.S. .91 SZ-H Ringed PS-Hyper Pumped Version Flight Modes

[HeliRaptor]

I now have 8 flights on the engine and wish to finalize flight modes and tuning.

I just finished setting up the Throttle and Pitch Curves on my DX7 for this engine on my Raptor 90.

I only had the Normal Flight Mode setup, mostly so I wouldn't be tempted to flip it around while the engine wasn't broken in. It turned out that I had to make some adjustments to the links to get the full pitch range as I was a bit off. Anyhow this is now all set.

Now I want to set the headspeed in Normal, Idle 1 and Idle 2.

Going by the formula to calculate headspeed for the specific engine I have it says to use 1814 RPM (Max Power / Gear Ratio = Max RPM) so that is 15000/8.27=1814 RPM

So I was wondering what are others running there Flight Modes at for this engine and gear ratio.

[HeliRaptor]

Here is the pitch setup for this machine.

I set my pitch curves up in Idle 1 and 2 to be the same (I will have different head speeds). I now have full collective range without binding, so I can now set the low end to -13 should I need to.

The Curves are as follows

Hold = -3 INH 0 5.5 11
Normal = -4 INH 0 5.5 11
Idle1 = -11.5 -5.5 0 5.5 11
Idle2 = -11.5 -5.5 0 5.5 11

[heli-cuzz]

Hi dennis, I noticed on your hold curve, your low point is set to -3. Maybe I'm wrong, but that seems a bit high{towards zero degrees}.
I set all my helis hold curves at bottom around -8 degrees. I like to push my autos down quickly. It seems to keep my rotors spooled a bit faster.

Unfortunately I'm not into the 90 world of helis yet, but will be in the very near future.

[HeliRaptor]

Doing this will help keep head speed up. Going to -8 seems to quickly deteriorate head speed in an auto. Keep in mind that if your head speed drops below 75% you will never recover from that, keeping it at -3 is enough to pull the machine down with the lease amount of drag / resistance on the blades. I typically set this up on all my machines and it works well.

I am no auto expert but it seems to work. I tried many different methods in the sim first and this seems to be the happy point for me / my skill.

I can see where your will work fast but if one has poor collective management that can actually hurt them rather than help them.

[HeliRaptor]

OK. Thinking further about my response, I figured I would give some Real World references for those that have no idea what I said. I am not the best at explaining things, I am better at understanding and doing. So here is some references that I used to learn this.

Some of you that know me from www.HeliRaptor.com may know that I started taking lessons to get my Private Helicopter Pilots License. Therefore I have to study the FAA Rotorcraft Flying Handbook (FAA-H-8083-21) printed in 2000. If you have a copy of this book then refer to Chapter 16 page 16-1 for Full Scale Helis and Autorotation Explanations.

Now for Model Helicopters I use Ray's Complete Helicopter Manual 3rd Edition for reference. If you goto Chapter 32 page 180 Ray discusses Autorotations and in some cases he mentions only using -2 for negative pitch, this varies with model, blade type and Transmitter Used.

Again, I am not an expert with this topic. I have much reference materials and have yet to even attempt an Auto on my 90 as I only have 8 flights on it and 4-5 of those were breaking in the motor and tuning. I have it pretty close to being dialed in now and hope to complete that today now that all pitch curves are set.

If all goes well, I should hopefully start working on inverted hovering with this machine as I spent all winter on the sim working on inverted hovering in all orientations. Hopefully if all goes well there will be some pics taken at the field today.

[Shawn K]

Keep in mind that if your head speed drops below 75% you will never recover from that,

That's not true at all. Given sufficient altitude (quite a bit), you can actually bring the blades to a near complete stop, then restart them, get them up to speed, and finish the auto normally.

Don't confuse the physics of full-scale flight with model aircraft. Model helicopters are capable of doing things that a full-scale bird could never do.

There's nothing wrong with running as much negative pitch as you have positive pitch in an auto. In fact, negative pitch is one of the tools you have to control the angle of descent, and your primary tool for regaining headspeed if you let it degrade too much too early in the auto.

Ray's book is not incorrect, but don't mistake it as being the final word. That's the difference between "book learning" and "real life learning". I've used symmetrical setups on all of my machines, and have done autos using everything from -12 degrees to nearly 0 degrees. It all depends on what your'e trying to do, and your level of skill as a pilot.

[HeliRaptor]

I do wish to state that I CLEARLY stated that I am NOT AN EXPERT in this topic, nor am I an expert at RC Helicopters. I have lots to learn and will from time to time make statements that are false, mostly because the topic at hand may be from book knowledge and not actual knowledge. I normally state this as above referencing my info source.

I have heard of Blade Stopping Autos and totally forgot about them. So I stand corrected here. But my statements are correct in a full scale machine.

The other thing I want to mention is that I do not claim to "Know it All" I have lots to learn just like many others in the hobby.

So in fairness to me and others who make a post and reference the source of the info, please consider the fact that we are being honest and just do not know and share your knowledge to help us grow ours.

I take no offense to someone correcting me or one of my posts especially if I am providing inaccurate info, it is not my intent to mislead or give false info. I appreciate the comment and learned something new.

[Shawn K]

You're not under the gun, Dennis. It's all good. ;)