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General control line discussion => Open Forum => Topic started by: kevin king on February 17, 2020, 09:06:18 AM
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Anyone know if Ro Jett engines are still being made? I have a 65 BSA RE on a header/muffler and want to know if a larger engine is available, hopefully without having to modified the air frame.
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Call Dub and ask him. He's easy to talk to.
Jerry
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Anyone know if Ro Jett engines are still being made? I have a 65 BSA RE on a header/muffler and want to know if a larger engine is available, hopefully without having to modified the air frame.
Yes, they are still made, the 67LS seems like it would be an upgrade for you. You would get better performance from a 61 on a pipe, but the 67 can run effectively on the muffler. There is also a 76, but I don't know if it fits the same mounts.
Brett
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Yes, they are still made, the 67LS seems like it would be an upgrade for you. You would get better performance from a 61 on a pipe, but the 67 can run effectively on the muffler. There is also a 76, but I don't know if it fits the same mounts.
Brett
It drops right in. The only difference it stands 1/4" taller and the exhaust port is about the same amount higher. Also if running on a pipe the pipe length will be two inches farther back so the pipe tunnel will need to be longer.
Dave
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I bought a RoJett 61 last fall, so far, I'm pleased with the engine. Dub Jett is very responsive, nice fellow! #^
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My recaller thinks that the .65's were found to have too thin a cylinder wall and were converted to .61's when compression dropped off.
Definitely call Dubby Jett and order a .67. SOP is to call, leaving a message and ask for him to call back. I've only had one talk with him, about converting a .76SE I bought used from Walter Hicks to RE...very painless. I fully expected to at least buy a new piston, but Dubby said the cylinders were ROUND and it wouldn't be required. I was pretty shocked, actually, but he was right...it has very good compression.
If anybody is running a RO-Jett .76 on a pipe, I'd be interested in pipe length, prop type/size and launch rpm. PM if you would, please. H^^ Steve
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Steve this is what I've used for about a decade now. Be sure you have the larger diameter .75/.76 size pipe. The .61 uses a little smaller one. I've found vast differences using different props. I haven't found any two blade props that perform for me. My favorite is the Mejlik 12.5 X 4.5 three blade. It will turn a VERY large prop but have found no benefit from doing so. I also pull the pitch out to 5.5- 6.0. I have used 7" but start to lose consistancy in run. Depending on what you are trying to use for pitch the launch RPM should be anywhere from 8000 to 8600. This is where other props will show big differences. If you use an Eather prop of similar dimensions and pitch you will need to drop the rpm way back or the lap time will be too fast. So here you might lower pitch on that prop. The bottom line is you will need to do a lot of experimenting to find the right combination for a certain airplane and flying speed. I usually set 3 or 4 at a given pitch then go fly them all and NOT TOUCH the needle. Record the rpm and lap time for each. You will either find the 'magic' prop or go back and re-set them all to a greater or lesser pitch and go fly them again. Once I get the pipe length set it will remain quite consistent. This will always fall 21 3/4" to 22" to the first baffle or +2" to the back of the can. Once you find your prop and lap time you can move the pipe in or out in small amounts to keep the lap about equal on both ends of the run. In other words, if the airplane gains speed toward the end of the run, pull the pipe out a little. If it goes rich push the pipe in.
I went into more detail than I know was asked for but there are a number of variables that can create a wide assortment of results. Should you begin with these ranges and methods I know you will find the sweet spot for you. BTW..I also use a venturi bore of .205 and 23-24% oil-1/2 castor. You won't need anything more than 7 ounces of fuel.
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Much appreciated, Dave! I've been running a Randy Aero AAC OS .46VF/pipe and a PA .51/pipe for the last 10 years, but must admit that they work fine without a lot of fussing with length...Randy's chart just works real well. I've been a fan of Brian Eather's undercambered props on both. They seem to pull better up high and handle overweight dogs better. Seem easier to set pitches, also. y1 Steve
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Thanks for the feedback guys. 👍
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Is there contact info for Dub anywhere. I recently picked up a Ro Jett 61 or 65 not sure which one lol and I'd like to get a pipe for it.
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http://www.rojett.net/images/green_logo_rojett.JPG
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Is there contact info for Dub anywhere. I recently picked up a Ro Jett 61 or 65 not sure which one lol and I'd like to get a pipe for it.
Jared you can get the pipe from Randy Smith....
Dave