Author Topic: RO-JETT 65 engine. (Read 8045 times)

Terry Bentley · « **on:** January 27, 2016, 01:57:48 PM »

Dose anyone have any feed back about the RO-JETT 65 engine?

Dave_Trible · « **Reply #1 on:** January 28, 2016, 01:45:52 PM »

I'm not sure Dub still makes the .65. You want the .61. Five or six years ago when I went to order my first big block engine after running the .40s for a long time I asked Dub for the .65. He said to me that I didn't want that but instead the .61. He said the .65 was a bored out .61 and the sleeve got too thin. The .61 has the same power and free of problems with the thin walled sleeve. The .67 however is altogether another engine with a good heavy sleeve and is a fine engine. I don't own one but used one in Rich Oliver's borrowed airplane for the team trials. It was flawless.

Dave

Greg L Bahrman · « **Reply #2 on:** February 03, 2016, 05:09:19 PM »

I had the same response from Dub at Ro-Jett. I had a 65 that I was having problems with and I returned it to Dub to rebuild. He rebuilt it back to a new 61 for a minimal charge. Good customer support.....Greg
P.S. He told me he was not going to do the 65 anymore.

Balsa Butcher · « **Reply #3 on:** February 03, 2016, 06:26:46 PM »

My 65 runs great however the above responses are correct. If it goes bad it will become a .61 in short order...not that that's a bad thing as the RoJett 61's are exceptionally nice stunt engines.

Randy Cuberly · « **Reply #4 on:** February 03, 2016, 07:57:05 PM »

I also have a .65 that runs very well and has not given any trouble at all. I believe the main trouble was indeed that Dub had trouble making the thin sleeves and that created an unacceptable scrap rate. However if you have a 65 I would not worry about using it. I've seen many run very well and in fact believe the "Great" Ted Fancher won the Nationals with one!

However there is no real disadvantage in the 61 as Brett Buck and many others have proven. I would add that the 67 although a bit heavier is a horse of a different color and I do mean Horse. A longer stroke and somewhat different way of running at slightly lower RPM. It will turn more prop and is indeed a "HORSE". I have been told that it will run without a pipe as well as with one and give excellent regulation. I intend to run mine on a pipe but think it may not be necessary from what I've been told!

Best of all they are available and service and parts are also available!

Randy Cuberly

Brett Buck · « **Reply #5 on:** February 03, 2016, 10:01:11 PM »

Quote from: Terry Bentley on January 27, 2016, 01:57:48 PM

Dose anyone have any feed back about the RO-JETT 65 engine?

Lots of people have run the 65 with success, but as noted, they don't appear to make it any more, in favor of the 61 and 67. All I can say is that my version of the RO-61BSE is the best stunt motor I have ever owned and *in my opinion* runs better than any of the other likely candidates. It's not as powerful as the PA 61, 65 or certainly the 75, but the run quality is stellar and I think that more than makes up for it, particularly in heavy air. The only other engine that is close is the PA75 with David's setup, but I think that is a matter of "lots of power" VS "better overall run.

When everything is working perfectly, I still think these engines are even with or even a slight advantage of the feed-back electric systems in heavy winds. The only issue is getting it exactly perfect and keeping it that way. I found a very good setup right before and during the 2003 NATs have run pretty much exactly the same setup on three different engines over the last 12 years, I have experimented around the nominal settings and always came back to the same point. It doesn't change from here to Muncie, aside from the fuel, and only at Tucson have I ever had to change the prop just to get it to work. You can adjust the run to the extent necessary with nitro and oil content.

The only problem I have ever had is with the rear bearing chipping. My first engine had a bad bearing at the 2003 NATs, although it ran very well despite the sound. In the past few years, I have had my #3 and then #2 engines also have the same issue. At no time did it seem to affect the way it ran and I won and was competitive in some big contests this year with my #2 engine sounding like a coffee grinder. It' a simple fix. I think my #1 engine has been retrofitted with a larger diameter bearing after my earlier issues, and it seemed to be fine the last time I ran it in 2007.

If you are going to get a new engine, get the RO-Jett 61 BSE "Brett version" and a few of the long venturis with the 1/16" "dribble hole" and set it up per the SSW post "RO-Jett setup from 2006 NATs". It runs substantially faster than many other systems but remains in a 4-stroke throughout.

Brett

FLOYD CARTER · « **Reply #6 on:** February 04, 2016, 06:45:11 PM »

The RO-Jett 61 BSE is so pretty, I didn't want to hide it under a cowling! So I designed PIED PIPER with upright engine to show it off. I'm hoping the image of Kokopilli will bring luck, as the southwest indians believe.

Floyd

Howard Rush · « **Reply #7 on:** February 05, 2016, 01:22:25 AM »

I think Dub had trouble machining those fentonite cylinder extenders he used to convert the .61 to a .65.

Jim Kraft · « **Reply #8 on:** February 05, 2016, 07:31:25 AM »

Fentonite ain't what it used to be. Should have used laminated chicken fat. It works much better, is much more pliant, and is fragrant. The old fentonite was known to cause warts in the republic of California, so they came up with a replacement that does not work near as well.

Dane Martin · « **Reply #9 on:** February 05, 2016, 08:14:34 AM »

Gotta be careful with that fentonite. It's much lighter than aluminium. That much fentonite being used could shave .02 sec off your lap times

Brett Buck · « **Reply #10 on:** February 05, 2016, 11:24:08 AM »

Quote from: Howard Rush on February 05, 2016, 01:22:25 AM

I think Dub had trouble machining those fentonite cylinder extenders he used to convert the .61 to a .65.

I use a zinc-lead-titanium alloy.

Brett

RandySmith · « **Reply #11 on:** February 05, 2016, 02:26:25 PM »

Quote from: Brett Buck on February 05, 2016, 11:24:08 AM

I use a zinc-lead-titanium alloy.

Brett

I like the ones cut otta spent uranium-cobalt alloy, great too if you need a little extra nose weight

Brett Buck · « **Reply #12 on:** February 05, 2016, 04:26:38 PM »

Quote from: RandySmith on February 05, 2016, 02:26:25 PM

I like the ones cut otta spent uranium-cobalt alloy, great too if you need a little extra nose weight

*Spent* uranium? How "in the box" can you get?

Brett

RandySmith · « **Reply #13 on:** February 05, 2016, 07:03:45 PM »

Quote from: Brett Buck on February 05, 2016, 04:26:38 PM

*Spent* uranium? How "in the box" can you get?

Brett

uhmmm Spent uranium/COBALT ALLOY !!! .... super trick stuff :-o
sometimes it gives a whole new meaning to "GLOW fuel..

Brett Buck · « **Reply #14 on:** February 05, 2016, 07:51:16 PM »

Quote from: RandySmith on February 05, 2016, 07:03:45 PM

uhmmm Spent uranium/COBALT ALLOY !!! .... super trick stuff :-o
sometimes it gives a whole new meaning to "GLOW fuel..

Use "unspent", more energy. Just don't get too much of it together in once place. And never race it in Hiroshima.

Another interesting feature of uranium (spent or otherwise) is that it can spontaneously combust. So, save on spark plugs, too.

Brett

Randy Cuberly · « **Reply #15 on:** February 08, 2016, 08:17:18 PM »

AAAAAAAAAHHHHhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh!!!!!!!!!!!!!!!!!!!!!!

Enough is enough........

Randy Cuberly

Brett Buck · « **Reply #16 on:** February 09, 2016, 12:46:45 AM »

Quote from: Randy Cuberly on February 08, 2016, 08:17:18 PM

AAAAAAAAAHHHHhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh!!!!!!!!!!!!!!!!!!!!!!

I predict that quotes from that video will become standards. As in:

Q: How do I modify the 40VF for a real stunt run?
A: Use a conrod made from a lead-zinc-titanium alloy.

Q: My Fox 35 quits on outside corners but I know that the bypass stuffer is stupid and won't try it
A: Stuff the bypass with Fentonite

Assertion: My ST -60 is WAY better than any piped engine, because it has a lot of torque.
Response: That's what Don Force told me!

and so on. I can make an accurate prediction because I know that's what I am going to do.

Brett

Steve Fitton · « **Reply #17 on:** February 10, 2016, 08:47:00 PM »

Quote from: Brett Buck on February 03, 2016, 10:01:11 PM

...When everything is working perfectly, I still think these engines are even with or even a slight advantage of the feed-back electric systems in heavy winds. The only issue is getting it exactly perfect and keeping it that way. I found a very good setup right before and during the 2003 NATs have run pretty much exactly the same setup on three different engines over the last 12 years, I have experimented around the nominal settings and always came back to the same point. It doesn't change from here to Muncie, aside from the fuel, and only at Tucson have I ever had to change the prop just to get it to work. You can adjust the run to the extent necessary with nitro and oil content...

Brett

Weren't you changing props at Muncie this year? Like on Thursday afternoon when the density altitude seemed to get so high?

Brett Buck · « **Reply #18 on:** February 10, 2016, 09:32:13 PM »

Quote from: Steve Fitton on February 10, 2016, 08:47:00 PM

Weren't you changing props at Muncie this year? Like on Thursday afternoon when the density altitude seemed to get so high?

I changed noseweight mulitple times but I don't recall a prop. I *did* change from a heavily-chipped one (from digging up the grass at Woodland for the last few years) to a new one that had something like an airfoil at the tips. But they were both 12.5-3.75s. I do occasionally experiment around with the pitch but for whatever reason, this airplane wants 3.75 and is not nearly as solid on 3.9, no matter how hot it gets. the previous airplane liked 3.9 better. The only time I switch is at Tucson, were I go to 4.1 and also to YS20/20, just to get it back in a constant 4-stroke.

The noseweight was an interesting experiment for at least two reasons. The first is that I can tell a distinct difference between a small aluminum prop washer, a small steel prop washer, and a large steel prop washer, and between a steel nut with part of the spinner stud cut off, and a complete stud. Some of them only differ by 3-4 *grams* on a 62 ounce airplane.

The other thing (and I discovered this at Tucson, too, probably because it's extreme enough to be very distinct) is quite counter-intuitive - in the thin air, it wants *more noseweight* and whatever handle spacing increase is required to get the desired sensitivity. I can leave the CG alone, get the spacing increased to get the same overall sensitivity, but it seems to lighten up the control effort in the middle of the corners. To get that right again, I have to add a touch of noseweight and increase the spacing even more to compensate. It's a marked change at Tucson, and some of the fiddling I did at the NATs last year was to see of the same thing happened at Muncie. Sure enough, same effect, to a lesser degree. Came back here, had to take it back out.

BTW, both Howard and Jim Aron suggested that this is a "princess and the pea" effect, but I won down in Madera after changing from aluminum to steel small prop washer, so even if it's all in my head, it works. I think it's more a matter of having spent so much time with the airplane (the second and third airplanes fly nearly identically, and I have been flying them for close to 20 years) that I can pick up even a slight change, AND, I know exactly what it has to feel like to be competitive.

Brett

Mark Scarborough · « **Reply #19 on:** February 11, 2016, 08:17:37 AM »

I can relate to the "princess and the pea" effect, not with models but with Bowling, I had similar things that would work to adjust,, most have no real effect on the stroke or release of the ball, but they definitely effect my brain, and 75% of the time it worked,,

now If I could find that for my flying I would be in fat city LOL

Scott Richlen · « **Reply #20 on:** February 15, 2016, 06:36:18 AM »

Certainly not a princess and pea affect! I found this to be mostly true for when I was flying my attic-find Ringmaster in OTS last summer....

Uh-huh, uh-huh, uh-huh

Steve Fitton · « **Reply #21 on:** February 16, 2016, 03:04:52 PM »

I had one good Princess and Pea moment, at a Marietta contest. I was flying my Classic model on a perfect day-ideal stunt conditions and the plane began the flight performing really well. When I hit the triangles, however, the handling was *off* - it didn't want to turn as crisp as it should have and felt oddly nose heavy. It was sufficiently "off" that my mind kept working throughout the flight, and as I flew the overhead 8 I suddenly figured it out! I had forgotten the *%$#@!!*&^!! squares. BOTH inside and outsides! To confirm this I looked over at the judges, and Derek made a "what the Hell you idiot!" gesture that confirmed my theory and that I had handed Bob Dixon a free victory.

The amount of fuel burned from the end of the outside rounds till the triangles must be miniscule, yet I was so oblivious to everything else that day that the trim change was the only cue to a problem-and I caught it.

Normally though, the plane can be out of trim by a *gross* amount, and instead of catching it, I end up mentally adapting to it and ignoring it, which doesn't work so well.

Randy Powell · « **Reply #22 on:** March 03, 2016, 04:04:51 PM »

Just as a note. I have a .65 and it ate a wrist pin retainer. Dub fixed it and it runs great again. Nice engine.

Ted Fancher · « **Reply #23 on:** May 25, 2016, 04:59:02 PM »

Quote from: Brett Buck on February 10, 2016, 09:32:13 PM

"snip"

The noseweight was an interesting experiment for at least two reasons. The first is that I can tell a distinct difference between a small aluminum prop washer, a small steel prop washer, and a large steel prop washer, and between a steel nut with part of the spinner stud cut off, and a complete stud. Some of them only differ by 3-4 *grams* on a 62 ounce airplane.

The other thing (and I discovered this at Tucson, too, probably because it's extreme enough to be very distinct) is quite counter-intuitive - in the thin air, it wants *more noseweight* and whatever handle spacing increase is required to get the desired sensitivity. I can leave the CG alone, get the spacing increased to get the same overall sensitivity, but it seems to lighten up the control effort in the middle of the corners. To get that right again, I have to add a touch of noseweight and increase the spacing even more to compensate. It's a marked change at Tucson, and some of the fiddling I did at the NATs last year was to see of the same thing happened at Muncie. Sure enough, same effect, to a lesser degree. Came back here, had to take it back out.

"snip"

Brett

Could be something along the lines of the Tucker experiment couldn't it? Manufactured tension under tension debilitating atmospherics? Just a thought.

Ted