Ringmaster Junior power plant choice

[Jeremy Chinn]

I picked up a Ringmaster Junior kit this afternoon. I plan to build it up as an easier to fly trainer for my son- easier than the baby Ringmaster with the TD.049 that is a bit hot/twitchy.

I’ve got two .15 engines that I think could be good choices. Both old RC engines from my collection, but I can either wire open the carb, or purchase a proper venturi/spraybar.

First is an Enya .15 III. 3303.

Second is an OS Max .15

I have a muffler for the OS, which is a positive, but may have to replace it anyway, so that might be a moot point.

Which would you choose and why?

(I did a bunch of forum searching and reading on each)

[Brett Buck]

I picked up a Ringmaster Junior kit this afternoon. I plan to build it up as an easier to fly trainer for my son- easier than the baby Ringmaster with the TD.049 that is a bit hot/twitchy.

I’ve got two .15 engines that I think could be good choices. Both old RC engines from my collection, but I can either wire open the carb, or purchase a proper venturi/spraybar.

First is an Enya .15 III. 3303.

Second is an OS Max .15

I have a muffler for the OS, which is a positive, but may have to replace it anyway, so that might be a moot point.

Which would you choose and why?

(I did a bunch of forum searching and reading on each)

  Either of those would be OK, this is a *very small* airplane. Mine had a Supertigre G20/.23 and it was a bomb, with speeds in the mid-90s. As a trainer, you want to make sure to keep the CG forward and more importantly, set the controls up to be very slow, that is, lots of handle movement to get maybe +-15-20 degrees of elevator motion. Set up like it suggests on the plans, with the stock elevator horn, it is WAY WAY TOO FAST. You don't need and could not use the usual +- 45 degrees of motion, it will stall long before that, and making the controls too fast will guarantee it will stall at the slightest movement of your hand.

   Also, replace the nose doublers with maybe 1/16 aircraft plywood. The kit luan plywood will collapse as soon as you try to tighten the engine. Same with the bellcrank mount, make that from 3/32 or a double layer of 1/16 aircraft ply, and reinforce the joint with the spar somehow, because the stock arrangement is very prone to breaking away from the spar during a pull test.

      Brett

[Dennis Toth]

To add to what Brett said for the bellcrank mount you can use 3/32" plywood plate between the center ribs, I like to add a piece of 3/32"balsa between the center ribs (with the grain running side to side) glued to the leading edge and spar then put the plywood bellcrank mount plate on top of that. This gives a very solid box to mount to.

Also, would suggest covering with Monokote/Ultracote film as it will take bouncing around without needing constant patching and will keep it light.

Best,   DennisT

[Carl Cisneros]

if you need a muffler for the Enya 15 III, then get it here:

https://www.ebay.com/itm/225148063114?hash=item346bdecd8a:g:2OAAAOSwENBhKSP3&amdata=enc%3AAQAIAAAA4CIlSv24z8WEpLTr488paxz5GmkpItXqGswsPWri8EQr4KTgLseNrB4nOPza7D0Wo%2BzDowRwstxhWhnAFZ8rZRbw7GNGZf%2FbY88clNWq8brbmH%2B5f8RI%2FSxPDIj6MEgVYN%2FbHkv4e6kCfiLuLDzfujylb6Yx4JBX4hmgwvGR7LsgkRf6gIOctq6MkAz1sNPAumo4GIAkSP%2FT1RQV3vX3CXNLhjr5WJU9lRqR31qnF2L42aVS33uVg8zkexyA4pNwmTVz1o4AWVeYchJsZCtauX%2FL2CaC%2FzzF6kUheKMMbvoz%7Ctkp%3ABk9SR-C7_7_4Yg

Bobby is great to work with.
I have bought from him several times and a great person to work with.

Carl

[Paul Smith]

I'm nearing completion on mine.
Out of many available engines I went with the OS Max LA 15.  It's light, runs good and I've got plenty of them.
The ones that don't pit well enough for Clown Racing can go on the Junior Ringmaster.

[Steve Dwyer]

I have two Ringmaster Juniors flying. One I found in a dumpster and rebuilt the other I scratch built. Both are the grandkids models one is the Mia Flyer and the other is the Rian Flyer with appropriate stick on vinyl names. Both have Fox 15s, one is a straight and the other slanted plug. They both go like the dickens on 40' lines. Once a year at the R-Fly-A Thon I bring out my old U-Reely, I'm to lazy to make up a set of 40' lines. The kids have struggled with the speed, and the .15 is a bit nose heavy so if I was to start over I'd go for a smaller engine.

Steve

[Jeremy Chinn]

Thanks for the suggestions all.

We flew one with a lengthened tail, reduced throws and an LA15. Was a great flyer and my son enjoyed it. The LA was really fussy to start however.

[Steve Dwyer]

LAs are no brainers to run. There's a gazillion threads here on getting an engine to run good, check them out you'll probably find the culprit.

Steve

[Steve Helmick]

While I haven't had an OS .15LA, I have run a .25LA. The starting problem I had was that I'd choke it to get fuel to the NV and then it would run back into the tank. When it started (finger style), it would quit before it drew fuel to the venturi. IMO, using an electric starter would fix that, so I can see why OS would be ok with that nonsense.

The NV was also a really loose fit in the threads of the spraybar, which I would have thought would cause needling problems or inconsistent running. Of course, being old (and fashioned), I just swapped the rear NV for a front NV assy. (4mm, K&B part from Mecoa). Also drilled the venturi out to .272" diameter, but remember, that was the .25.

For a trainer, I'd suggest the OS Max .15...but I'd like to know exactly what model OS Max .15 it is, because if it's a Max I, II or III type, it'd be a shame to waste it on a trainer. If it's a Max "S" type, then have at it. I'd be interested in purchasing a Max III for use on a free flight model.

The reason I wouldn't suggest the Enya is that we have club history with Enya .19's, and they didn't hold up to crashing on pavement, especially with a muffler. The crankcase split wide open. The muffler hits and torques the case. Cutting the muffler mounting bolts about 1/2 way through might be in order with any engine you choose. Having a quiet-ish engine would help a beginner stay calm and make learning to fly easier.  Steve

[Mike Hazel]

Also consider using a .10 size engine.  I built a Jr RM using .10 power, 45 foot lines seem about right.

[Dave Hull]

I tried an Enya .15-III (3303) on a Magician 15 for 52' lines. It had more vibration than the OS .15LA and the plane didn't like that. But it had plenty of power and ran fine, if I could keep the fuel feeding. I tried a second .15-III and it was the same. Some of these smaller "Junior" planes have pretty flimsy noses. On the other hand, I've got a beat up hand-me-down Junior Flite Streak that I put a Mickey One-Niner redhead on and it is a sweet combination. But there isn't enough room for a big enough tank....

Hope your project works out well!

Dave

[Brett Buck]

Also consider using a .10 size engine.  I built a Jr RM using .10 power, 45 foot lines seem about right.

    If we are going outside the engines he listed, I would try a Hornet 09.

      Brett

[Jeremy Chinn]

Thanks much for all the feedback and ideas.

Muffler is important both from a personal standpoint, and from not wanting to lose another flying site.

I put the two engines I have currently (the Enya and the OS) on the test stand yesterday afternoon. Unfortunately, the OS needs a rod. I could buy a muffler and a venturi/NVA for the Enya, but after spending that, I could have also just bought another engine.

With yesterday's test stand experience in mind and feedback from a bunch of other similar threads on the forum, I went ahead and plunked down some $$'s for an LA.15 that was already set up with a venturi/NVA and had a muffler. Cost was similar to or less than if I'd bought the same parts for the Enya I've got.

I plan to kit bash the RingJR a bit, so it should be fun in the end 

[Jim Kraft]

 
   I learned to fly inverted on one back in the early 60's with the dreaded Fox 15x. It also flew a Shark 15 with flaps. I gave the engine away a few years ago as it was still running great. Must of gotten one of the good ones even though I heard there was no such thing. The Junior Ring fly's pretty well if kept light and as Brett says, keep the controls limited.

[Leonard Bourel]

My 2 cents worth. Use an OS FP 10 on the junior ringer with light 52 foot lines What a great little combo and YES dumb down the controls so it is just a dream to fly.

[Brett Buck]

Thanks much for all the feedback and ideas.

Muffler is important both from a personal standpoint, and from not wanting to lose another flying site.

I put the two engines I have currently (the Enya and the OS) on the test stand yesterday afternoon. Unfortunately, the OS needs a rod. I could buy a muffler and a venturi/NVA for the Enya, but after spending that, I could have also just bought another engine.

With yesterday's test stand experience in mind and feedback from a bunch of other similar threads on the forum, I went ahead and plunked down some $$'s for an LA.15 that was already set up with a venturi/NVA and had a muffler. Cost was similar to or less than if I'd bought the same parts for the Enya I've got.

I plan to kit bash the RingJR a bit, so it should be fun in the end 

  That is LOTS of power for a Ringmaster Jr. The Ringmaster Jr is smaller than a lot of .049 stunt planes.  It will fly a full-size Ringmaster, although not with a lot of authority. It will work and be reliable, but keeping it at a reasonable speed will be very difficult.

    You are running into the usual problem - when it says ".09-19", they mean an 09-19 from 1950, not from 2015. There's a huge difference between what you would expect from a 1950 engine and a modern one, even a mild sport engine like the 15LA.

   Since you have it, go ahead, but plan on finding a 8-3 prop somewhere and 60' lines, at least for training purposes. And plan on building a larger airplane later.

      Brett

[Dennis Toth]

If you plan on using the long 60' lines (although I would stay with like 55') with the OS FP15 don't try to fly it to slow. Pick a day with light winds to do the first few flights (~5-7 mph). Use a 8 x3 or 8x4 prop. Use a uniflow tank with the vent in the free airstream. Set the engine to a just lean clean 2 cycle run, use fuel with at least 25% (Syn/Castor blend ok) total oil. I suggest you look into using Spectra lines. I like the FINS 40G brand. I have used the Fins 40G 40Lb test on my full Ringmaster for over a year and a half with no issues. I select the Lb test by taking the model weight in pounds, times 10 then double it and get the nearest available. So for the Ringmaster Jr, should weight about 20oz divide by 16 oz/lb = 1.25 lbs, times 10 = 12.5 times 2 = 25 Lb Test. Here is the link: https://www.finsfishing.com/products/fins-40g-10-50lb?variant=44039388299575 you can do a search of local fishing supply stores but can also find it online in various lengths. Here is a link on this forum to Adventures in Spectra that show a reliable way to make up the end loop for the line set. https://stunthanger.com/smf/open-forum/adventures-in-spectra/

Best,    DennisT

[Brett Buck]

If you plan on using the long 60' lines (although I would stay with like 55') with the OS FP15 don't try to fly it to slow.

   Flying too slow is not likely to be an issue, or even possible! The 15LA has *vastly* more power than any 19 available in the early 50s when the airplane was designed.

I select the Lb test by taking the model weight in pounds, times 10 then double it and get the nearest available. So for the Ringmaster Jr, should weight about 20oz divide by 16 oz/lb = 1.25 lbs, times 10 = 12.5 times 2 = 25 Lb Test. Here is the link: https://www.finsfishing.com/products/fins-40g-10-50lb?variant=44039388299575 you can do a search of local fishing supply stores but can also find it online in various lengths. Here is a link on this forum to Adventures in Spectra that show a reliable way to make up the end loop for the line set. https://stunthanger.com/smf/open-forum/adventures-in-spectra/

   I don't know about spectra to give advice on it, but, to be entirely crystal clear, the test rating can be whatever you want, but 10G of pull test is plenty adequate, it does not make it safer to actually pull it to 20Gs, probably, it comes apart, but at the very least it will tend to overstress everything.

    For training, 20 ounces is OK, but ideally you want it much lighter than that for stunt performance. A lot of full-size Ringmasters are down in the low 20 ounce range. I seem to recall mine was less than 20 with a G20/.23, kit wood, and craftsmanship so poor than something fell off of it every flight, to the point I never ran out a tank of gas. Part of it was the 90+ mph.

     Brett

[Dennis Toth]

To clarify the line Lb Test selection method - Since there is no official recommendations as to how to select Spectra line weight this is what I came up with. I was looking at the various Spectra lines available, what I was looking for was a way to get less drag to save some amp draw on my electric Ringmaster to allow a small capacity, lighter weight pack.

Normally, for anything under 40 oz I would used 0.012" SS cable. In the Adventure in Spectra post Dennis Adamisin showed some breaking data on the various SS cables. The 0.012" has a break strength of 25 Lbs. The FINS 40G line is very thin for its strength, the 25 Lb Test is 0.008" diameter. I did the double cause the 0.008" just seemed very thin and the 45 Lb test is 0.009" diameter and almost double the strength. It has the drag equivalent of 0.010 or 0.011" SS lines and saved 4% battery capacity which is what I was looking for. The combat guys use like 65 Lb test and that seemed like it would be much more than needed for stunt. It is a simple method that gives a safe line Lb Test. Another way that gives about the same answer is to take the model weight in oz and get the nearest Lb test line. As we get more data on how strong the Spectra lines are the selection method can be refined.

Best,    DennisT

[Jeremy Chinn]

After reading through all of your responses again and a few more old threads I found in the forum, I went looking through my collection for something else to use. I've got a small collection of Norvel engines, including a pair of Norvel .074's (including one that is basically NIB). I ran the .074's up on the test stand yesterday after work and both are strong, but one was giving me about 1k higher on the same prop. I found a bunch of instances of people running this on lightly built Ringmaster Jr's on 45-50ft lines.

The big brown truck arrived today and delivered a RingJr kit still in the plastic. I think we all enjoy when we've got something new in the shop... Building days to come.

Oh yeah, the .15LA will definitely have another home when it arrives.

[frank mccune]

   Hello All:

    This post may upset a few people but I thought that I would add it for grins.

     This Summer, I flew 2  Ringmaster Jr. planes with Diesel engines.  One engine was a MVVS 1.5 cc or .09 cu. in.  The other Jr. was powered by a MVVS 2 cc or .12 cu. in.  These were flown on 40 feet of fishing line.  Perfect flights were flown.  Mufflers were not needed and the fuel cost a bit more than $10.00 per liter.  Due to health reasons, an electric starter was used.  My flying mate was very happy flying his Blue Pants powered by an ED Hunter 2.5 cc Diesel that he bought in 1955!

       Just food for thought,

       Frank McCune