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HeliHobby . Ron’s HeliProz South . Century Helicopter

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Tandem Rotor Helis Vertol Chinook > chinook pitch settings
 
 
hercflyer
Heliman
Location: Colorado Springs, CO. USA

Hi there,

I have a hirobo that I am having some difficulty with. I tried to fly it today, and the front end would lift up quickly (even though I was giving full forward cyclic), feel as if it were to go out of control, and I'd have to let off the power.

My feelimg is that the pitch angles on the front set are way too aggressive, and the rear set are too tame. At 0 throttle, the pitch of the rear blades was approximately -2, and the front set was at +3 or 4.

I don't know for sure because I bought it like this, and I started it simply to do a few engine runs, but like any other guy, I couldn't resist an attempt at a hover. I figured that that the heads were set because there were the obvious tell tale signs that it had been done, ie, blades were balanced, rod linkages were color coded to the respective blades, and the mixer was already programmed.

Additionally, I fly the DX7, and all I have is a 7 channel receiver, which means that I had to remove the GV-1 governor. Is that bad? I'm looking for some input or help on appropriate pitch settings for both the front and back, and are the rod lengths that are listed in the directions accurate, or is each bird particular as to how each one "likes" to be set (differences in construction tolerances account for miniature adjustments to make the swashplates level).

I think you know what i mean. Anyway, i'm just looking for some help, and you guys sound like you really know what you are doing. Anything will do, and I certainly do look forward to your reply.

-J

Go big or go home!
08-03-2007 12:11 AM
HOMEPAGE  
 
 
Free Bird
Senior Heliman
Location: Somewhere in the USA

The pitch between the 2 rotors is way off. Low pitch should be about -2 on both heads, 5 to 6 degrees hovering and 9 degrees at full throttle/pitch. If anything, the front rotor should be +1 degree more than the rear so it has the proper "sit" (slightly nose high) while hovering. Not using a governor is not a show stopper, I hover mine without one.

The heads need to be setup with the throttle/collective stick at 50% and all of the servo arms and bellcranks need to be 90 degrees. Do you have the manual? If so, I'd go back to step 19 (CH-46 and I assume that the CH-47 is the same) and check all of the pushrods to ensure that they are the correct lengths and the servo arms/bellcranks are also correct. That's what I used and it was very close for hovering. Don't assume all is well because someone "color coded" the blades and the linkages. Also, check the CG as these models tend to be nose heavy. Have you been warned about the belt tension? If not, it needs to be really tight. If the heads come out of sync, the blades will hit each other. Another tip is to run the blades fairly tight in the grips, again you don't want them to lead/lag a lot for obvious reasons.

Good Luck!

FB

I meant to do that!
08-03-2007 02:06 AM
 
 
doorman
Elite Veteran
Location: E.Berne, NY

Sounds Right To Me!!!!!!!!!!!!!!

Sounds as if FB has you headed in the right direction....
I have mine in FF and am not using a governor...(but I don't use them on much of anything anyway!!!!!)so you are OK there too....
Just take you time and get things 100% as per the manual as FB suggested and then just take your time... another thing to look at CLOSELY is the follower location to make sure that is where it is supposed to be... or you will get some "funny" control inputs..... Take your time and READ THE BOOK!!!!!
These things really do fly and they look GREAT doing it!!!! And hopefully, someone will get some shots of FB and myself flying them together this Sunday!!!!!

Best of luck and ask away while you are getting it going!!!!!Stan

And we do need pic's!!!!!!!!!!!!!!!

If there is a cure for this, please don't tell me about it!!!
08-03-2007 02:15 AM
 
 
Free Bird
Senior Heliman
Location: Somewhere in the USA

Weather is looking good Stan! Can't wait for Sunday! Unfortunately my Vertol is still without the body. Looking forward to seeing another tandam!

FB

I meant to do that!
08-03-2007 02:28 AM
 
 
hercflyer
Heliman
Location: Colorado Springs, CO. USA

Dude,

You guys are awesome!!! Thank you so much for replying so quickly!
I am not relatively new to RC helis, and since I have real time in helis, my arrogance gets the best of me sometimes. I can fly ok (rc), but I am really getting into the "right way" to set up helis. You know, mechanically zero on the servos, level swashplate, etc, etc. So I welcome the input, and I will take all I can get. I fly my scale birds with a friend who has 20 plus years in rc helis, and I get all my knowledge from him, but this tandem is a new breed to us, so to speak.

So thanks once again, and keep the info coming, I gladly welcome it!

I have decided to use a Futaba 9chp (pcm) to fly the chinook, and I will be putting the GV-1 back on. As far as the belt tension goes, no I was not informed of how tight it must be, but I did notice that the tension on the belt was pretty tight, so I think we're ok there.

Upon closer inspection of the CH-47 blade angles, it was all wrong. The info I gave you earlier was incorrect. One blade on each head had different values compared to the other 2 blades on each respective head. And the values for the blade pitch on the front rotor was double that of the rear.

I do have the manual, and I am going to take your advice, Free Bird, and I'm to go over the manual with a fine tooth comb. I am not sure what the CG is yet, but I'm thinking of using a separate battery (to power lights and other scale items) to help correct that issue should it arise. What do you have to say about that? Have you ever heard of anyone using a separate battery to do this? Any way, my novel here is finished. But here are a few pics of the bird as it sits now.

Again, thank you both for such a speedy reply, and I look forward to any knowledge that you can impart to me.

-J



Go big or go home!
08-03-2007 05:54 AM
HOMEPAGE  
 
 
hercflyer
Heliman
Location: Colorado Springs, CO. USA

Doorman,

Could you be a little more specific about your comment on the follower being in the right place, and also elaborate on the funny control inputs. Thanks!

-J

Go big or go home!
08-03-2007 05:56 AM
HOMEPAGE  
 
 
doorman
Elite Veteran
Location: E.Berne, NY

Radius Block

On page 34 of my manual, it shows how to set the radius block (follower) so that the ball from the swash is 90 degrees to the actual blade grip... this is setting your head timing/phase for the 3 bladed head....
Don't worry too much about this being totally different from anything that you have done in the past... it is just two heli's stuck together!!!! And you get to attempt to find out how it will work!!!! (GoTTa Love It!!:cool
Reading that manual over a coulple of times and then going over the actual machine will put you into the ball park so that it will hover and then you can fine tune from there...Jeff Green is using Futaba in his and can help you with the actual radio settings.. not sure what FB is using...
This is my first attempt at one also and I have to tell you, it will make you look two and three times prior to making any adjustment and if you do one head you need to do the other too!!! But it is not bad once you get going on it.... I am glad that you took FB's advise and found that there were things out of sorts... so take your time and go over every link, pushrod, and servo connection and make certain they match the book and you will be on your way....
Page 47 shows the belt tension location to check the tightness and it is VERY important that it be this snug....
As far as your battery question goes, no problem using two.... I have a 3400 mah sub c pack at the very rear of the mechanics in the bay under the drive pulley for the rear head along with about 4 oz of lead to get the CG where it is needed (pg 47 again)...
So, feel free to contact either one of us if we can be of any further help and let us know how you are doing with it.... it is an amazing machine....(2000 parts trying to get away from each other instead of JUST a 1000 on a single headed machine.... this is sick)

Stan

FB.. don't worry they fly fine NAKED!!!!!!!!! See you Sunday....

If there is a cure for this, please don't tell me about it!!!
08-03-2007 10:47 AM
 
 
hercflyer
Heliman
Location: Colorado Springs, CO. USA

Doorman,

Thank you for the response, I will put the advice to good use.

I apologize in advance for sounding like a broken record, but what did you mean about the "funny input" statement (re:another thing to look at CLOSELY is the follower location to make sure that is where it is supposed to be... or you will get some "funny" control inputs.....). What type of heli response should I be looking for to indicate that something is not right. Also, I have a vibration in the rear head that resonates throughout the rear of the frame. I'm guessing that it is because the blade angles on each blade are off. Without seeing it, would you think that is a fair assessment, or is there something else going on that I'm not aware of or do not yet know to look for?

Again I appreciate all the advice, and I will be sure to keep you informed of my progress, seeing as how ya'll (you and FB) are somewhat involved now, more so out appreciation for the time you are taking to help me. After these prior questions are answered, I think I will be on autopilot until my project is finished. Can't wait to show off the final product. This is an awesome project!


-J

Go big or go home!
08-04-2007 04:09 AM
HOMEPAGE  
 
 
doorman
Elite Veteran
Location: E.Berne, NY

"funny" control inputs?????

No problem at all....glad to try and help out....

The funny inputs will make the unit feel as if it is very "mushy"(!!!) or just like it is floating and not doing what you want it to... the best way that I can describe it is that it will be hard to turn one way and/or not the other....and in fact what is happening is that the heads are "mixing" the commands at the wrong time and actually fighting your original input (best way I can describe it!! I am sure there is a much more tech'y way)....and on this machine it is double the fun!!!! So if you are having a problem turning left or right from the hover, go back to the radius block and look again...Hope this makes a little more sense to you...

As far as your vibration on the rear head.... if your blades are not in track, YES, this will cause vibrations and unwanted movements...
Also, check the weight of each blade and try to match the three for each head as close as possible...

Good luck and we will be waiting to hear from you...

Stan

If there is a cure for this, please don't tell me about it!!!
08-04-2007 11:11 AM
 
 
Free Bird
Senior Heliman
Location: Somewhere in the USA

herc,

What doorman is refering to is the radius block that attaches to the inner ring of the swashplate. Its position determines the phasing/timing of control inputs to the head. If it's not positioned properly, when control inputs are given, the heli will not move correctly to those inputs. Example: if you want the heli to move forward, and it goes forward and right, the phasing is off. The opposite will happen moving the heli backwards, except it'll slide to the left. I can only imagine if both heads are out of phase.


page 34 of the manual has the directions and a diagram of the head and the radius block showing the proper timing. After hovering the model, minor tweaks can be made to correct any trim issues.

I too had some vibration that I finally got rid of with doorman's help. We found out the the engine wasn't coming on the pipe. I switched from 30% to 15% nitro and leaned in the engine. It made a lot of difference. Thanks doorman!

BTW ... doorman and I got together yesterday and we had a blast flying our Vertols. I got some stick time on his for comparision. Both models felt very close while hovering.

Here's a couple of pics from yesterday.



I meant to do that!
08-07-2007 01:38 AM
 
 
hercflyer
Heliman
Location: Colorado Springs, CO. USA

Doorman and Freebird,

Alot of good info, I am printing this all this as we speak and using it to help put this chinook into the air. Thanks so much for all the input. I will see that it gets put to good use. I'll send pics when my project is complete. It'll either be a very successful and beautiful flight, or a smokin' hole (LOL!!!). There are some other issues that I will dealing with to make this a one-of-a-kind bird, ie, nav lights, strobes, raise/lower cargo ramp, etc. Wish me luck!

-Jason

Go big or go home!
08-07-2007 05:59 AM
HOMEPAGE  
 
 
hercflyer
Heliman
Location: Colorado Springs, CO. USA

Ok guys,

Sorry, no pics tonight, but I am making some real progress. I took ya'lls advice and picked a page (17) and started there. I have gotten all the way to checking the lengths of the linkage rods. The manual doesn't explain why the swashplate to blade grip linkage rods are different lengths in the front and rear head. Care to shed some light?

I am curious though, the linkage rods from the swashplate to the blade grips are at a 45 degree angle. Is that normal? Would it be possible to see a picture (close-up) of your swashplates?

Also, is retreating blade stall and flapping a relevant issue in the way these things are set-up? I'm just now reading and learning what these terms mean and their characteristics, I just haven't figured out if they apply to the CH-47.

Hope all is well. Thanks in advance for your assistance.

-Jason

Go big or go home!
08-10-2007 06:22 AM
HOMEPAGE  
 
 
Free Bird
Senior Heliman
Location: Somewhere in the USA

I'll post some pic tonight.

FB

I meant to do that!
08-10-2007 09:31 AM
 
 
Free Bird
Senior Heliman
Location: Somewhere in the USA

Quote 
I have gotten all the way to checking the lengths of the linkage rods. The manual doesn't explain why the swashplate to blade grip linkage rods are different lengths in the front and rear head. Care to shed some light?

That's because the rear mast is a little taller than the front.

Quote 
I am curious though, the linkage rods from the swashplate to the blade grips are at a 45 degree angle. Is that normal? Would it be possible to see a picture (close-up) of your swashplates?

Look at the pics below, they should be angled slightly, but not at 45 degrees. Mine are at maybe 10 degrees. Don't be fooled by the photos, the angles aren't as great as they seem in the pics. It's the angle of the rod from the inner ring to the blade grip makes it look greater than it is.

Quote 
Also, is retreating blade stall and flapping a relevant issue in the way these things are set-up? I'm just now reading and learning what these terms mean and their characteristics, I just haven't figured out if they apply to the CH-47.

Because the blades are counter-rotating, retreating blade stall shouldn't be a problem. I haven't had mine in full blown forward flight. Maybe somebody who flies theirs around could chime in with their experiences?

FB



I meant to do that!
08-10-2007 11:58 PM
 
 
hercflyer
Heliman
Location: Colorado Springs, CO. USA

Thank you for the pics! Mine look exactly the same.

PROGRESS: I now have all the linkage rods to spec, the gyro has been adjusted for the Futaba 9CHP, and the blades are next. After that, a test hover. The motor runs flawlessly, and there doesn't seem to be an issue there. I am using Youngblood 30%, to compensate using an O.S. .50
at altitude (6200' elev.). Pictures to follow soon (proof of thanks for all your input), and the gratitude of a fledgling heli pilot! I also have a flying partner that is putting his 20+ years of experience towards this project, props (or should I say rotors) to Mike Singels!

-Jason

Go big or go home!
08-12-2007 06:10 AM
HOMEPAGE  
 
 
hercflyer
Heliman
Location: Colorado Springs, CO. USA

Smokin' hole

Well guys, it's off to the drawing board. The test flight did not go so well. The heli was set up according to the instructions, linkage rods were all the proper lengths, blade pitch was correct and equal (although we used a standard pitch gauge, maybe that was the problem), and both swahplates were leveled. The first attempt at a hover was unsuccessful.

The heli came up tail first. My flying buddy and I adjusted the linkages (shorter in the rear, and longer in the front), to make the nose come up a little before the rest lifted off the ground.

Well, it finally did after a few more tries at adjusting the linkages. The nose came up slightly, then the tail and started to move up off the ground and forward (as it should).....then it nosed up sharply, suddenly (and with out any response from the controls, as if it had a mind of it's own), and leaned hard to the left and beat itself to death with its own rotor blades.

Any one want to buy hirobo ch47 parts? Just kidding! Any ideas?

-Jason

Pics soon to come

Go big or go home!
09-01-2007 09:39 PM
HOMEPAGE  
 
 
doorman
Elite Veteran
Location: E.Berne, NY

Any New's????????????

Hope the damage was not too extreme....
How soon will you be putting it back into the air???
Don't let it beat you.... they really do fly.....

Stan

If there is a cure for this, please don't tell me about it!!!
09-05-2007 01:24 PM
 
 
hercflyer
Heliman
Location: Colorado Springs, CO. USA

Damages to chinook

Doorman,

No, thankfully, there wasn't much damage. Busted rear blades, and bent blade grip linkages, so far. It really is frustrating, I did exactly what the directions said to do, and it didn't go as planned. I am thinking that it had something to do with the blade pitch. I need to get a pitch gauge for that thing! Like fake nails, I must press on!

-Jason

Go big or go home!
09-12-2007 09:38 PM
HOMEPAGE  
 
 
hercflyer
Heliman
Location: Colorado Springs, CO. USA

How soon till it's airborne????????

Doorman,

It'll be a long while before it's airborne. I have so many projects going on, that I may not get the time to set this thing up for a bit. I am starting an internet company that focuses on electric and turbine heli's, and also does repair work. So all my energy, time, and money are going into this. So I may sell it for parts, and get another one later when I have more time to devote to it. Know of anyone that may be interested?

-Jason

Go big or go home!
09-12-2007 09:42 PM
HOMEPAGE  
 
 
Chinook
Heliman
Location: Nijverdal - Netherlands

Hi all,

Just wanted to let you know that we are testing with another Chinook, a little bigger.


We are using the Helitronix new tandem mixer. We got that advise from Richard Addington. he's flying the Vario ch47 with success !.

We are just starting to test with the 3rd revision of our frame.

More information on Our wbesite

Machiel Broekman
09-16-2007 02:33 PM
HOMEPAGE  
 
 
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MTA Hobbies . MRC/Altech Marketing USA . Gyro Hobbies

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Tandem Rotor Helis Vertol Chinook > chinook pitch settings
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