RunRyder - Hirobo CH-47 Chinook - Build (updated October 8th, 08)

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Tandem Rotor Helis Vertol Chinook > Hirobo CH-47 Chinook - Build (updated October 8th, 08)

Camel Jokey
Heliman
Location: Who knows?

Hi Guys

I flew my CH-47 yesterday & you can see from the photos I enjoyed my self.

I noticed the heli started to make a funny noise after the third flight and the governor started to pulse the the throttle, indicating a breakdown.

When I inspected the helicopter I found the main gear in this state. amazing I didn't crash.

I flew the helicopter for 15 flights with no fus to check everything, it seems that when I put the body on it strips the main gear, I think it is caused by two factors, A) excessive heat B) high torque loading. There is alot of friction heat created between the drive pinion & main gear during flight add to that engine/exhaust heat and this little gear can't take it, Headseed is 1700rpm.

This has occured TWICE now, I have checked the clearance & gear back lash & it appears to be OK.

I'm a bit lost on what to do next, I fly in Dubai where the abient temperature is generally higher than most places so components really get tested here, however yesterday the temp was only 32C, not too bad.

I'm considering trying to get a maingear with broarder teeth or get a local manufacturing company to make me a metal gear to take the heat & machine cooling fins into it in order to dissipate the heat.

Any comments/sugesstons would be apreciated.

Maybe I'll contact Jeff Green, does anybody have a working email for this guy?

I'll post all of my settings next week when I get time.

11-11-2006 Over year old.

rcadd1ct
Elite Veteran
Location: Richardson, Texas

PM MRC-hirobo.

Looks like the mesh was not right, though.

Only the top part of the teeth are gone. On the ones I strip (not on a tandem) the teeth are gone from the root out.

-RCA .......... Making Cuisinarts Fly!!!!!!!

11-11-2006 Over year old.

tow cobra
Heliman
Location: Riverhead, NY

I have done the same thing to my main gear.

This also happened to me only when I put the body on mine as well. After about 5 minutes of flight, it made a strange sound and then it just seemed to begin to slip and when I took it down, my main gear looked just like yours.

It is not an issue of mesh because there is almost no adjustability in this model for this.

The unfortunate part is that this gear is about $65. I think that the material properties are not strong enough for the torque required to turn both rotors when pushed by the 50 engine.

I have been less aggressive with this helicopter since stripping the gear and it hasn't done this since.

11-11-2006 Over year old.

skycom
Senior Heliman
Location: Shropshire, UK

I had the same thing happen to my chinook after about a dozen flights (without the fuselage fitted). I couldn't find any particular reason why, the gear meshing wasn't tight and the heli had only been hovered to set it up.
I replaced the gear with one from a shuttle, and I also had a quick UK one way bearing unit and fitted that.
Its only has a few flights since but is holding up ok.
Maybe there is an issue with the main gears supplied in the original kits?

http://www.smhc.org.uk/
QUK Team Pilot

11-19-2006 Over year old.

the Wasp
rrProfessor
Location: Vt

time to call Jeff Green !!

Jim

Jim
Buzz Buzz Buzz

11-19-2006 Over year old.

Camel Jokey
Heliman
Location: Who knows?

Hi Skycom.

You say that you replaced the maingear with one from a shuttle??

Do you mean the moulded plastic one?
Has it been OK, how manyflights do you have on it now?

I'll PM Jeff Green & see what he has to say.

11-19-2006 Over year old.

skycom
Senior Heliman
Location: Shropshire, UK

I've got about 6 flights since I changed it. Seems ok so far, although there wasn't any sign that the original one was wearing at all, until it let go during a flight. Fortunately, the chinny was nice and low and no damage resulted.
The gear I had with the QUK unit was delrin, but it is intended for a shuttle. You may find a delrin gear on *bay, could be worth a look

http://www.smhc.org.uk/
QUK Team Pilot

11-19-2006 Over year old.

tow cobra
Heliman
Location: Riverhead, NY

I'm looking for a new set of chinook blades after some scuffs to the stock ones. I called MRC last week and was told that they were not in stock in the US right now (this may have changed in the past week but they told me it could be a month).

Have any of you guys successfully tried any alternative blades for the Hirobo Chinook? If so, where can they be purchased?

11-20-2006 Over year old.

vroomz28
Senior Heliman
Location: Barstow, California

Okay,

My CH-47 Chinook flies again. The mixing fix works. I had originally to change some of the gyro setting for the mixing unit. My first flight using the Hirobo recommended settings had the pitch and yaw gyros reversed. The 1st hover attempt 9 months ago was almost disastrous. After fixing the two axis of the gyro, it hovered, but the two swash plates didn’t move correctly.

When giving foreword cyclic inputs, there should be an decrease in collective on the front mast, and an increase on the rear swash. Somehow I had made it so both swash-plates just tilted with no accompanying collective changes. Emile and I had flown it and found this made it fly (really) weird, but it could fly.

After fixing this setting, the helicopter seems to be behaving better.

More flights to follow……..

Skids are for kids!

My gallery:
http://www.runryder.com/helicopter/gallery/37191/

11-22-2006 Over year old.

dgshaffer
Elite Veteran
Location: New Jersey

When giving foreword cyclic inputs, there should be an decrease in collective on the front mast

The front pitch doesn't decrease!. There's a mix setting in the mixer that will increase the rear pitch with the foreword elevator input.

Glad to herar it's flying better for you. I fly with a JR radio and had to make a lot of changes in servo direction as well as gyro direction. I think they're set up for Futaba from the factory.

Have any of you guys successfully tried any alternative blades for the Hirobo Chinook?

This is an ongoing issue. High price and limited availability. MS Composite makes a 470mm that will work but it's symmetrical and unlike the flat bottomed Hirobo blades, they don't have the same lift characteristics. The root also needs to be shimmed quite a bit.

11-22-2006 Over year old.

jlabat
Heliman
Location: San Carlos, CA, USA

Any updates on the Main Gear issues?

01-07-2007 Over year old.

footlock
Senior Heliman
Location: berks

when i hd a chinnook i used a pair of Hi PRO product blades from japan - specially made for the chinook . They were really good you can order them from ISHEI MOKEI in Japan if they still do them.
cheers
FL

01-07-2007 Over year old.

Camel Jokey
Heliman
Location: Who knows?

Yep, the gear issues are still ongoing, I have been in touch with jeff green, a very helpfull chap.

I'm planning another flight on friday to check things out & will post the results, however I also have a German company manufacturing an alloy gear for the Chinook designed to carry the obvious torque & temperature loads associated with this application.

Once full testing has been completed & I'm satisfied with the result, I will be supplying those who wish to upgrade to an alloy gear with the contact details of the German gear manufacturer.

Keep your eye's on this post.........

01-09-2007 Over year old.

tow cobra
Heliman
Location: Riverhead, NY

Did Jeff indicate that others have had the gear problem that we've experienced?

Did he have any suggestions to avoid stripping the gear in normal flight?

01-09-2007 Over year old.

tow cobra
Heliman
Location: Riverhead, NY

Blades

Also, along the lines of the blades, I susbstituted some blades that I obtained from Century Heli on my chinook.

They are made for a 30 size heli, 530mm in length and a bit wider than the stock blades but they fit the blade grip pretty well (no shimming or trimming) although they are a little tight in rotation but this is easily fixed by shaving the end a minimal amount.

This is the link for them:

http://www.heli-world.com/detail.aspx?ID=2870

They are only $19.95 for a pair so it was just $60 for the full set for the Chinook versus $200 from MRC for the Hirobo blades so I figured it was worth the chance since I've gone through a few sets of blades (As have others from the posts I've read).

So far, it hovers fairly well with these blades (a lot of lift) but I'm still fine tuning the machine so I haven't gone in to FFF yet.

I was wondering if anyone saw any drawback to using these blades on this machine (especially given the cost savings).

01-09-2007 Over year old.

modtron
Veteran
Location: Oxford. UK

If the 30 size blades you are about to use are for a standard head set-up, they will be to light and the centre of gravity will be in the wrong place.
You've already spent your biggest outlay on the machine and it's equipment.
Why not just stick to what it was designed to be used with and enjoy flying it the way it was supposed to be?

modtron
Oxford UK

01-09-2007 Over year old.

HOMEPAGE

skycom
Senior Heliman
Location: Shropshire, UK

NHP make carbon blades for the Chinook:

http://www.revolutionmodels.co.uk/a...BLADES_165.html

Down at the bottom of the page

http://www.smhc.org.uk/
QUK Team Pilot

01-09-2007 Over year old.

modtron
Veteran
Location: Oxford. UK

I have tried the NHP blades in the past on someone elses model.

Personally, I did not think they flew as nice as the Hirobo GRP blades.

The Hirobo GRP blades are narrow in width and semi-symetrical in section and they work very well.

The NHP blades are much wider in width and symetrical in section. Which means that the ratio of lift to rpm has totally changed.

We found that the machine needed to rev much faster with the NHP's, where as with the Hirobo blades, a govenor rpm of 1500 was just perfect.

modtron
Oxford UK

01-09-2007 Over year old.

HOMEPAGE

Camel Jokey
Heliman
Location: Who knows?

Modtron.

what do you mean by "Hirobo GRP" blades?

01-10-2007 Over year old.

modtron
Veteran
Location: Oxford. UK

Hi Camel Jokey,

Hirobo GRP blades for the Chinook & Vertol......

0406-086 - right hand rotation
0406-087 - left hand rotation

Retail cost in Japan = 35,000 yen per set. Contact ishii Mokei or similar for a discounted price.

Hope this helps, they do fly better with these.

modtron
Oxford UK

01-10-2007 Over year old.

HOMEPAGE

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Tandem Rotor Helis Vertol Chinook > Hirobo CH-47 Chinook - Build (updated October 8th, 08)

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