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Author Topic: Ro-Jett76 with a side muffler and Dynam 13x6.3x3 propeller  (Read 1326 times)

Offline Matt Piatkowski

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Ro-Jett76 with a side muffler and Dynam 13x6.3x3 propeller
« on: February 13, 2021, 03:24:24 PM »
Hello,
I have received Dynam 13x7x3 propeller.
After some sanding and tweaking the pitch is 6.2-6.3" now.

I know that Ro-Jett76 with a side muffler will theoretically work correctly with such a prop.
Stalker76 works very well with 13x6.3x3 carbon composite propellers made in Ukraine but there is one problem

The Dynam propeller is made of nylon-carbon dust laminate that is less stiff than epoxy - carbon cloth laminate.
Dynam is also heavier but it is secondary at this moment.

I wonder if I can safely use this Dynam propeller with Ro-Jett76?

I could not find the confirmation that this propeller is safe to use with such a powerful engine.
Thank you,
M






Offline Air Ministry .

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Re: Ro-Jett76 with a side muffler and Dynam 13x6.3x3 propeller
« Reply #1 on: February 13, 2021, 09:38:42 PM »
STAND CLEAR ! .

Offline Brett Buck

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Re: Ro-Jett76 with a side muffler and Dynam 13x6.3x3 propeller
« Reply #2 on: February 13, 2021, 10:06:58 PM »
I have never heard of that brand of propellor, and am not familiar with that kind of construction, so I don't know.

    Brett

Offline Lauri Malila

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Re: Ro-Jett76 with a side muffler and Dynam 13x6.3x3 propeller
« Reply #3 on: February 14, 2021, 02:44:36 AM »
Wouldn’t that high a pitch be too much for such Schnuerle engine? Also, looking at the pictures, it looks kind of crap. Thick blades, flimsy looking blade root and cheap glass filled nylon injection molding. I vote no. L

Offline Dave_Trible

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Re: Ro-Jett76 with a side muffler and Dynam 13x6.3x3 propeller
« Reply #4 on: February 14, 2021, 05:12:34 AM »
Wouldn’t that high a pitch be too much for such Schnuerle engine? Also, looking at the pictures, it looks kind of crap. Thick blades, flimsy looking blade root and cheap glass filled nylon injection molding. I vote no. L
  This is the range of pitch I use on these engines.  The rpm ranges from 8000-8500 depending on the individual prop.  it will be running mostly in a four cycle with an occasional break under load.  I don't know anything about this prop though.  I've never trusted anything but carbon/epoxy on these engines,  other than break in where I start with a 10-6 wood prop to keep it cool.  I believe trying to run the .76 at high rpm is a mistake.  You run the risk of it unloading on you.  Then you are trying to hold a grizzly bear on a set of lines.  I do run them on a pipe which controls such tendencies. I'd be more careful on a muffler.  The prop?  Wouldn't try it if you aren't sure. The engine might chuck it.

Dave

After finding a photo of this prop I would definitely NOT use it!
« Last Edit: February 14, 2021, 06:19:47 AM by Dave_Trible »
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Offline Carl Cisneros

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Re: Ro-Jett76 with a side muffler and Dynam 13x6.3x3 propeller
« Reply #5 on: February 14, 2021, 09:09:48 AM »
if it is this propeller then do not use it!!!!!!!!!

It is for Electric use.

Dynam manufactures props and other things for electric powered aircraft.

Carl

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Offline Matt Piatkowski

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Re: Ro-Jett76 with a side muffler and Dynam 13x6.3x3 propeller
« Reply #6 on: February 14, 2021, 11:30:27 AM »
Hi Carl,
Ok...I got it: "electric-only".
Thank you for the clarification that should have been supplied by the manufacturer.
They do not care as long as you buy something from them.
The shitty reality of web-based purchases these days.

Thanks,
M
 

Offline Brett Buck

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Re: Ro-Jett76 with a side muffler and Dynam 13x6.3x3 propeller
« Reply #7 on: February 14, 2021, 11:54:31 AM »
Wouldn’t that high a pitch be too much for such Schnuerle engine?

   Probably, but Sancho Panza told me to skip it this time.

    Brett

Offline Lauri Malila

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Re: Ro-Jett76 with a side muffler and Dynam 13x6.3x3 propeller
« Reply #8 on: February 14, 2021, 01:40:01 PM »
   Probably, but Sancho Panza told me to skip it this time.

    Brett

..and then, there is allways the head shims🙄 L

Offline Brett Buck

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Re: Ro-Jett76 with a side muffler and Dynam 13x6.3x3 propeller
« Reply #9 on: February 14, 2021, 05:36:00 PM »
..and then, there is allways the head shims🙄 L

   And milling engine mount lugs.

    Brett

Offline Brett Buck

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Re: Ro-Jett76 with a side muffler and Dynam 13x6.3x3 propeller
« Reply #10 on: February 14, 2021, 05:47:08 PM »
They do not care as long as you buy something from them.
The shitty reality of web-based purchases these days.

   Yes, sort of, but it is unrealistic to expect hobby manufacturers from keeping up with developments in events that most people don't even know exists. And there are plenty of people even in stunt who don't know that a RO-Jett 76 exists, and only a few dozen that have seen one run.

   That's why we get almost everything from cottage industries, not large operations.

    Brett

Offline Steve Helmick

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Re: Ro-Jett76 with a side muffler and Dynam 13x6.3x3 propeller
« Reply #11 on: February 14, 2021, 07:02:18 PM »
I talked to Paul about the RO-Jet .76. He said it liked bigger props/more load than he had on hand, and his airplane lost the killer corner he demands. I'm pretty certain he used it with a pipe. It seems to me that going to 4 blades (undercambered if possible) might fix both.

My suggestion is to email Brian Eather and make arrangements to buy some 4 blade props from him. They come "raw", so you can sand them and trim them as you wish. He also ran the RO-Jet .76 on a pipe for awhile, so you might ask about that.

Alternatively, Chris and Alan make CF 3 bladers for PA .75's that should work alright. They are made for Randy Smith, and don't know if they could be bought direct or not. I'd ask, if only because dealing with Customs delays and exchange rate would be a PITA.  y1 Steve 
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