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Blitz Helicopters Avro 90 > Avro belt drive
 
 
ofir
Senior Heliman
Location: tel aviv - israel

Hi all.
I am thinking about buying AVRO: the only thing that's bugging me is the belt drive.

what is most important to me is the machine reliability.
is the belt reliable? does it cause to some power loss?

You don't mess with the ofir...
03-20-2008 10:13 PM
 
 
stanc
Veteran
Location: Conroe, TX

YES

NO

Stan

Stan
Will Work for Electrons
03-21-2008 10:56 AM
 
 
Bond007
Senior Heliman
Location: Leicestershire UK

I don't know of any issues with the belt

Mine has 3 gallons through it now and the belt is as good as new

It does make for a super smooth and quiet transmission, and the power of the model is simply staggering

You shouldn't have any concerns.

Blitz Avro, Trex 500
03-21-2008 11:25 AM
 
 
colsy
Elite Veteran
Location: Cambridge, UK

Quote 
and the power of the model is simply staggering

Where ! and compared to what ?

Col.

Only Quote From Experience.
03-21-2008 11:47 AM
HOMEPAGE  
 
 
DOKEY
rrProfessor
Location: Northampton UK

You should not have any power concerns, it seems hardly any different from other 90's, like you would expect.



http://uk.youtube.com/watch?v=9Ov7N...feature=related

Check the gallery!
03-21-2008 11:53 AM
HOMEPAGE  
 
 
ofir
Senior Heliman
Location: tel aviv - israel

I must say that in this video it looks a bit heavy.

You don't mess with the ofir...
03-23-2008 05:36 PM
 
 
DOKEY
rrProfessor
Location: Northampton UK

To be fair, it was only the second outing I had had with the Avro, and also not being my heli, I am always very reserved.
To add, the engine was not 100% to my liking (you should be able to tell from the engine sound on the climbing part of the piro loops), Andy (realraptors.co.uk) had only just added the omi carb and this was the second flight, it now has a governor fitted and I believe a carbsmart as well, so I have a feeling the engine side of things will be very sweet now.

Check the gallery!
03-23-2008 08:18 PM
HOMEPAGE  
 
 
ofir
Senior Heliman
Location: tel aviv - israel

I saw a belt drive in a very old heli, so this is not new - if it's good then why its not popular?

You don't mess with the ofir...
03-23-2008 08:36 PM
 
 
Bond007
Senior Heliman
Location: Leicestershire UK

Cost for one thing. Fashion for another. It's not the current trend as you say. Doesn't make it a bad system though.

I'm guessing it is a heavier system than direct gearing, but it does make for a very smooth and quiet transmission and also it's probably more costly to produce, but the Blitz team decided it was a better system for their design.

I know that Blitz tested different ways to gear the model, and finally decided on the belt setup. See the quote from their website;

Quote 
The high performance two-stage transmission, consisting of drive belt and helical machine cut gears, minimises resonance and delivers a smooth transition throughout the power band.

I remember the Futura was a belt drive, and that always impressed me as to how quiet the transmission system was.

colsy

Quote 
Where ! and compared to what ?

Errrrrrrr...in the air and compared to my Trex N

Sean

Blitz Avro, Trex 500
03-23-2008 09:30 PM
 
 
hi5
New Heliman
Location: Stillwater, OK

Concur with Bood007.
The belt drive is quieter and offers more compliance, ie less torsionals are transmitted into the rotor head. Also, the two stage tranny allows for smaller gears. Plus you're a little less exposed to tolerance stack up as to the location of the engine vs the belt gear. Great design. I like it ....
03-24-2008 02:49 AM
 
 
Andy Hinton
Heliman
Location: Cheshire, United Kingdom

Avro - Go for it

Go for it you will be impressed. It's smooth and so stable in sportsmans setup its a dream to fly. Put a lot of fuel through mine now and I have not had a single problem!

Best machine out there without a doubt.

Gone flyin!!
03-24-2008 08:29 AM
 
 
Lolly
Heliman
Location: San Diego

Avro seems to have a lot of design concepts from the Futura SE that I fly. The belt drive is very smooth and it really is a quiet transmission. However, I question it's optimal appropriateness for an ultra 3D machine. i.e. less weight is critical. Having a 2 stage gear box has it's benifits, but a single stage, with careful alignment (as is the norm) is still quite smooth, but would be more efficient, have lower mass and less to break and wear. That being said, I have over 3,000 flights with the original belt...I have the new one waiting to be installed, but the original just keeps going. IN FACT, my buddy installed a new belt in his Futura SE with a slight misallignment. This caused the belt to slide down the gear onto the aluminum side frame causing it to grind down in flight (heard a horrible buzz for a few seconds) leaving about 1mm of belt left over. That was sufficient to spin the head et al and fly around modestly untill the landing. What a testament to its durability and ability to come back aive and well!

The Avro seems like a great quality heli and capable 90. I would love to see it in detail and get my hands on it.

L
04-29-2008 03:36 PM
 
 
ErichF
Key Veteran
Location: Odessa, FL 33556 (Tampa Area)

The Avro has a very similar transmission to the Caliber 90 which I fly. The main differences are the location of the one way bearing and the cooling fan. The primary drive belt absorbs much of the engine pulses that can cause one bearing failures, gear failures, hardware stresses and looseness, etc. Also, it's nice to just bolt the engine in and go, without aligning a darn thing.

04-29-2008 05:43 PM
 
 
kirk
Veteran
Location: Thornton, Colorado

I think that you could argue that a 2 stage belt driven transmission is just as good if not better than a direct gear type transmission. You do have more surface area contacting the pulleys (the belt), but you do not have the radial bearing, bearing blocks, 1 way bearing and alignment issues associated with a start shaft the goes completely thru the helicopter. You also have less rotating mass that needs to be aligned perfectly...

The way I see it is that when the frame of the helicopter flexes it puts the start shaft in a bind which in turn causes drag, and takes power away from you motor. All helicopters flex and bend which can and will cause drag on the drive train.

On the Avro I like how simple the setup is and it feels like it has just as much power as the other 90's I have had without all the headaches associated with the start shaft and bearings. It is also very smooth and quiet.

Another nice feature is that if I need to I can pull a motor out in about 5 minutes and have it back in about 10 minutes. I do not have to worry about alignment, bearing getting stuck on the start shaft, or pinions spinning in the radial bearings...

I have about 3 gallons thru mine so far and the belt still looks brand new with no signs of wear anywhere. Its a pretty neat system for sure!!

Kirk
04-29-2008 09:45 PM
 
 
Lolly
Heliman
Location: San Diego

The belt drive does a great job in absorbing some shock loading, vibration, tolerating a little misalignment from flex etc. It is smooth and the transmission is quieter in general. Most likely contributed to the durability of my Futura SE. However, where performance is paramount, I believe a simpler single stage transmission, with lower parts count and resultant mass, is more efficient delivering more power to the head. Less expensive, less things to break. Furthermore, the benefit of concentrating mass closer to the CG is a reduced moment of inertia resulting in faster overall heli response. With proper design and gear meshing, current heli power train design with single pinion and gear is optimal when aerobatic and high G performance is the goal.

Ease of manitenance is nice but I suspect of secondary importance (Ar least it is for me). Also I have had many types of helis and never noticed any issues with the juxtaposition of the starter hex and its assembly with different designs. If everything runs smoothly as it should, the start procedure imparts minimal stress on the assembly. I never did like the gas engine pull start procedure though, where most people hold the head with one hand, foot on one skid and yank on the starter chord "in between". As a consequence I've seen ball links popped, bent rods, and all kinds of instant misalignments and vibration resulting from hard yanking. I used to start my gas heli by just holding onto the skids with my feet and one hand holding the head to prevent an accidental hot start disaster. No side loading of any kind. Worked great.
04-30-2008 05:15 AM
 
 
ErichF
Key Veteran
Location: Odessa, FL 33556 (Tampa Area)

Quote 
I never did like the gas engine pull start procedure though, where most people hold the head with one hand, foot on one skid and yank on the starter chord "in between"..... I used to start my gas heli by just holding onto the skids with my feet and one hand holding the head to prevent an accidental hot start disaster. No side loading of any kind.

Care to explain what appears to be a complete contradiction in what you said? I don't get it, sorry.

I don't think you ever saw Wayne Mann's Caliber 90 fly, or else you'd probably retract what you believe about primary belt drives. He has no performance issues, with a heli that weighs nearly 12.5 pounds and can fly nearly 90mph. This from a heli with three belt drives in total. Also, at least with the Caliber 90, the engine is actually mounted up higher than it would be, had it been a typical clutch/pinion arrangement. The belt drive passes above the main gear. In fact, the front face of the front engine bearing is level with the top of the main gear on the Caliber 90. Looking at the Blitz belt arrangement, I can see that they could have adjusted the frame layout to put the belt drive above the main gear, but the tail drive would be an issue.

I respectfully think you over estimate the "perfection" that is a single stage transmission, or at least under estimate the primary belt drive two stage tranny.
05-01-2008 12:07 AM
 
 
Lolly
Heliman
Location: San Diego

No contradiction at all. I hold the head to stop it from starting to rotate. The load against the pull start is mostly counterbalanced on the skids. Hope that clears it up.

Being able to fly at 90 mph has nothing to do with acceleration which is what 3D is all about and therefore it's all about mass and moments of intertia.

05-01-2008 01:45 AM
 
 
ErichF
Key Veteran
Location: Odessa, FL 33556 (Tampa Area)

Quote 
No contradiction at all. I hold the head to stop it from starting to rotate. The load against the pull start is mostly counterbalanced on the skids. Hope that clears it up.

As mud

First, you say you never did like the gas engine pull start procedure where most people hold the head with one hand, foot on one skid and yank on the starter.

Then you said you start your gas heli by just holding onto the skids with your feet and one hand holding the head.

Quote 
Being able to fly at 90 mph has nothing to do with acceleration

How do you get 12.5 pounds to 90 mph, then?

All in fun, now...
05-01-2008 01:56 AM
 
 
Lolly
Heliman
Location: San Diego

1. Not liking the start procedure has nothing to do with the start procedure.

2. Read up on Newtons Second Law and the mud (suspended particles in solution) will settle.

3. 3D or extreme aerobatics demands a higher response capability of the heli. The heli undergoes high acceleration (change in speed and direction). The stress limitations of the components would dictate the lowest possible mass and moments of inertia so that the heli does not disintegrate in flight. "It's all about acceleration" is an emphasis on high G maneuvers and resultant extreme loads resulting from typical 3D flight. Reaching 90 mph, yes the heli accelerates to get there. But the heavier the heli , the lower the acceleration all other things being equal. If you're drag racng, a 10.5 lb heli would reach 90 mph faster meaning higher acceleration.

This is all 10th grade stuff.

05-01-2008 02:24 AM
 
 
ErichF
Key Veteran
Location: Odessa, FL 33556 (Tampa Area)

Well, it was a fun conversation until you resorted to this condescending drivel:

Quote 
Read up on Newtons Second Law and the mud (suspended particles in solution) will settle

Quote 
This is all 10th grade stuff.

So, OK, have a good one.
05-01-2008 02:52 AM
 
 
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Blitz Helicopters Avro 90 > Avro belt drive
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