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Fast Lad Performance . Ace Hobby . Esprit Model

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Robbe Cuatro - Millennium - Nova - Dyna-X > Tank melt / OS91 / Hatori 984
 
 
Michel-Henri
Senior Heliman
Location: On the mediterranean coast

Hi,

I am installing an OS91 on my Millie2 with a Hatori 984.

Alas, the muffler runs almost flush with the fuel tank, where the latter protrudes from the frames.

I thought of manufacturing a 2.5 mm thich spacer (between exhaust port and muffler) to increase clearance to about 3mm.

Is this enough distance to avoid melting the fuel tank?
Any suggestions on how to solve the problem differently?

Thanks,

Michel-Henri
06-16-2002 Over year old.
 
 
Christian Rose
Heliman
Location: Tengling, Germany

Hello,

I think, the idea with the spacer is good, but the spacer should be about 3-4mm for bigger distance to the tank (i think 4mm Distance between Muffler an Tank is good).

I use OS 91 in my three Futura Nova together with a Zimmermann muffler. With this, the space between muffler and tank is about 5mm. Until one year of F3C Training there were no problems the above mentioned problems.

best regards
Christian
06-16-2002 Over year old.
 
 
Roger Hamilton
Senior Heliman
Location: Surrey, England

Sorry, bit off subject here but I wanted to know about your experience with the OS91 in the Nova, Christian.

I've had some probs with getting good results from a Futura SE/OS91 installation. What gear ratio (how many teeth on the clutch bell) are you running, have you upgraded the clutch, fan or made any changes to the engine?

FWIW, I think 4 mil would be OK, Alternatively do you think you could get away with putting a slight angle on the spacer which would give you better spacing at the tank end. Not strictly proper engineering but the angle could be very slight to give an extra couple of mms near the tank and I don't think it would sverely compromise the engine coupling...
06-16-2002 Over year old.
HOMEPAGE  
 
 
Christian Rose
Heliman
Location: Tengling, Germany

Hello Dodger,

what problems do you have with your engine? BTW: You can mail me direct if you have still problems with your engine.

I am very glad with my three OS SX-91. The gear ration is 1:7,57 and for this a conversion set is available from robbe since the beginning of this year. It includes all necessary parts like the 390mm Belt, a 27T Clutch belt and a special clutch. I use the robbe aluminum fan for better cooling, too. I made no changes or modifications on the engine and use the original carb. (OS 60L i think). Fuel is Cool Power with 15% Nitro, muffler is from Zimmermann and as Glow Plug is use the Enya 5.

Hope this helps.

Best regards
Christian
06-17-2002 Over year old.
 
 
Michel-Henri
Senior Heliman
Location: On the mediterranean coast

A quick update:

I manufactured a 3mm thick spacer for the muffler neck, and glued a 2mm. thick carbon plate onto the protruding side of the tank to work as a heat shield.
Did 7 flights today without any sign of problems.

Hope this helps.
06-23-2002 Over year old.
 
 
sluggo
Elite Veteran
Location: Kitchener Ont

Here is a cool way a bud of mine fixed this problem with his milli 80. http://www.bob00.d2g.com/gallery/mi...e70054_jpg.html

He used a small tie rap and some small clunk line and tied it around the muffler where the tank was contacting it. So far it is working great.

Chris
06-24-2002 Over year old.
HOMEPAGE  
 
 
Michel-Henri
Senior Heliman
Location: On the mediterranean coast

Thanks Sluggo,

Actually I had seen that trick mentioned somewhere but was worried on 2 accounts:

1/ I would have to apply force to insert the tube between the tank and muffler, which would stress the one-piece muffler neck. Was worried about cracks developing from vibration.

2/ Also this wouldn't solve the proximity problem and I was worried that radiated heat might still be a problem during idling when the rotor is not blowing air (it seems this plastic starts getting soft at around 85 deg.C and melts at approx 135 C)

FWIW, there seems to be 2 generations of Millie tanks, one thinwalled and the other thicker. If your friend is landed with the thinner one, the tank expansion due to the YS pressure might become a problem - as it would tend to stress the muffler outwards when expanding.

Let us know how your friends' solution works on the longterm.
06-24-2002 Over year old.
 
 
Michel-Henri
Senior Heliman
Location: On the mediterranean coast

It just struck me,
if the tiewrap can take the heat then shouldn't the tank too?

Any idea what are the temperatures reached by the muffler on its outer skin?
06-24-2002 Over year old.
 
 
z11355
rrMaster
Location: 10000 is enough time wasted.

very different plastics. The ties are first off
insulated by the silicone rubber and second
DO get brittle after a while. The tank plastic
is a thinwalled polyethylene which has a low
melt point.
06-24-2002 Over year old.
HOMEPAGE  
 
 
rappyfly
Senior Heliman
Location: Toronto, ONT

It is my 2 cent...

The Hatori 984 is short neck design wihich is for freya only.
It has a dent on third engine mounting hold and avoid cutting out too much material from Freya canopy when installed.

I also use the trick which bob00 show on the web site. I use KSJ chunk line go around it and double layer at contact point. The muffler does pushed outward by the tank pressure. But, remember, the end section does viberate...even without contact. If you are worry about the solution, then let the tank touch the muffler.

IMHO,It is the most feasible solution.
06-24-2002 Over year old.
 
 
RCMarket
Key Veteran
Location: Belgium , Europe

solution

This is the solution for Tank Melting


More solutions at my gallery

Alex (Formerly Known as Futurac )
06-24-2002 Over year old.
 
 
Blair
Key Veteran
Location: Republic of Canuckistan

Zimmerman Crack pipe

That looks like a good solution to the famous Zimmerman cracked header scenario too.

Blair
06-25-2002 Over year old.
 
 
Michel-Henri
Senior Heliman
Location: On the mediterranean coast

Millie reference nbr

Quote 
The Hatori 984 is short neck design which is for freya only.


What is the proper muffler Reference for the Millie/OS91 ?
06-25-2002 Over year old.
 
 
RCMarket
Key Veteran
Location: Belgium , Europe

Muffler solution

I think the newest mufflers from Zimmermann are a good solution for all problems.
Also avaliable with short flange/pipe, with teflon coupler.

Alex (Formerly Known as Futurac )
06-25-2002 Over year old.
 
 
rappyfly
Senior Heliman
Location: Toronto, ONT

Hatori 982 will work with Milli.
Front and rare head Hatori (80,90) has same head length so it makes no difference on milli.
06-25-2002 Over year old.
 
 
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Robbe Cuatro - Millennium - Nova - Dyna-X > Tank melt / OS91 / Hatori 984
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