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Author Topic: Engines for Slow Open Power  (Read 5427 times)
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RobinB
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« Reply #75 on: December 12, 2011, 05:08:41 PM »

Good question, John. The top flyers over here with 'big' SLOP planes have wing areas around 550 sq.in.
With an engine weight of nearly 7 ozs, if you use the usual rules of thumb of engine weight being around one third of all-up,
and a target loading of a minimum of 25 sq.in. / oz. then you're going to end up with a wing about that size.

I'm thinking 8:1 AR wing, NACA 4409, 85%CG  i.e., a standard setup. Maybe a 5-panel wing, raked tips, maybe thin balsa D-box.


I'm open to suggestions  - anyone got any ideas? We could create a HPASLOP  Grin

Robin
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Scottl0413
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« Reply #76 on: December 12, 2011, 06:21:33 PM »

Robin, a no. of planes come to mind for your SLOP and the re-worked O.S. 20.
- 585 galaxy, geodetic wing construction, great flyer, build the fus. a little longer and put the fin on the back. Ref.   pic. attached.
- 565 Shoccer,geodetic wing construction, I like it alot
- 600 Satellite, my fav.
- 511 Pillferred Pearl, proovin (sp) winner!
All of these would be winners IMHO!

Scott
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gossie
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« Reply #77 on: December 12, 2011, 09:08:39 PM »

I agree with Scott. 
The big Galaxie would or should be quite good.   I had one years ago with a Super Tigre 29 in it that went like a rocket.   Mine had the fuselage also built a little longer with the fin on the rear.  I also had it on AR and VIT though, but with care full trimming it should be okay on a 20.   
In fact Scott and I talked a few years ago about that from memory.
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Sandgroper
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« Reply #78 on: December 14, 2011, 03:41:49 AM »

Nice K&B 20 Robin and a lovely job on the machining John the NV looks far better than a bought one.I have added a 1/8" alloy backplate-mount and a OS10 rear needle to suit the 525 sq T-Bird on mine,the nozzle is a Norvel 049 spraybar with the nv end soldered shut.The venturi is a Cox Conquest item machined to fit and only has one fuel hole.

Great choice of models Scott,lenghtening the Galaxy fuselage to have a rear fin is a good mod,I had a 1/2a version and didn`t like the combined tail/fin .The Shocer 750 and Tartar 800(needs the fuse mod as well) caught my eye a while ago and in the 550+ sq inch sizes perfect.The Thunder Tiger GP 20 and the Magnum GP21 are both OS FP20 clones and usually cheaper, there is a  Magnum 21 under the title" Magnum GP RC engine with extra airplane parts"on US ebay at 10 bucks today but he wants 40 bucks international shipping.


Phil
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« Last Edit: December 14, 2011, 03:58:12 AM by Sandgroper » Logged
flydean1
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« Reply #79 on: December 14, 2011, 11:15:14 PM »

Very nice looking engine.  Do your fingers get a bit toasty so close to the head?

Another modern design to consider is Don DeLoach's Super Pearl 542.  He sells a short kit as well as the CAD plans.  I have so far finished the basic fuselage and stab.  Wing to come next.  A really well-engineered kit.
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Sandgroper
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« Reply #80 on: December 16, 2011, 12:35:57 AM »

Great so we can expect  a few Super Pearl construction pics.I will contact Don about the Pearl short kits.
I modified an old bracket, the hole was slotted and the NV could be moved away but I have revised it to this setup below
I was tempted to omit the wing dowels and have a couple of alli hooks instead.The "hole" is about 7/16 I am not sure if it will need an insert on pressure?
Found this weird device outside and used it for checking CG`s and a couple of shots of a T34 SLOP.


Phil
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Scottl0413
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« Reply #81 on: December 16, 2011, 10:23:13 AM »

I'm not familiar with the SLOP rules for engines, but I was wondering whether a Super Tigre 23 G20 would be legal? It's not Schnueler ported, can run on suction, but is a bearinged engine not a bushed engine.

Scott
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gossie
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« Reply #82 on: December 16, 2011, 03:39:53 PM »

Nice spot of engineering there 'groper, and a nicely built model too.   She'll go like crazy with the open venturi on pressure.
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Sandgroper
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« Reply #83 on: December 16, 2011, 11:11:57 PM »

I'm not familiar with the SLOP rules for engines, but I was wondering whether a Super Tigre 23 G20 would be legal? It's not Schnueler ported, can run on suction, but is a bearinged engine not plain bearing engine.

Scott
They have to be plain bearing Scott, what are the US  SLOP rules? I can`t find em on the NFFS website-UK and Australian SLOP rules allow Schnuerle ported engines because the class was conceived as a  restricted Open Power class, restricting the class to any 3.5cc plain bearing engine on suction was a good idea it kept the class cheap with many off the shelf and out the draw motors competitive.
With the no moving surface rule even nostalga and sixties designs were competitive  so they became as popular as more efficient modern designs.
I agree that the Slop rules should be changed to include different engine types such as ball raced diesels and glows like Oliver Tigers , Super Tigers and the current Veco 21- but they should be run on suction,plain bearing crossflow or loop scavenged  Nostalga engines could run on pressure.

Phil




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danberry
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« Reply #84 on: December 17, 2011, 10:04:36 AM »

There are no standardized SLOP rules on this side of the pond. They are club events.
The Colorado bunch runs the event with an RPM restriction. Bigger engines get less RPM. There is no restriction on pressure fuel systems, which is good. Just controlling the rpm is sufficient for their event.
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Sandgroper
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« Reply #85 on: December 17, 2011, 10:40:49 AM »

That would be Slow Gas? is there an engine size limit? rev limits?engine runs?and the number of flights

Phil
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danberry
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« Reply #86 on: December 17, 2011, 10:45:44 AM »

The Magnificent Moutain Men Club has the rules. I don't know all of the rules. Most of the planes that get flown are TD 049s or NosGas planes.
I do know that the larger engines have a lower rpm limit.
I don't know all of the rules. I've never been to Colorado and haven't flown it.
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Sandgroper
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« Reply #87 on: December 17, 2011, 11:16:51 AM »

Thanks Dan,
I will look them up,Slop is only a club and State event here but we have been getting good fields with a few RC old timer fliers giving power a go for the first time in Slop using Nos gas models on suction, its great to see a few more happy faces out there .Starting to warm up down here  31 deg c  today.

Phil
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Randy Reynolds
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« Reply #88 on: December 17, 2011, 11:35:33 AM »

The Magnificent Mountain Men SLOP rules are:

* MMM Slow Open Power Rules


ENGINES - Any Engine Allowed flying to the RPM limits below:

20,000 RPM maximum for engines up to and including .10 cu in displacement

18,000 RPM maximum for engines over .10 cu in displacement

 
AIRPLANES - Any Design is eligible

Auto surfaces not permitted

FLIGHT RULES - 3 Minute Maxes

Flight rules same as AMA Gas except as follows:

 12-second engine run hand launch

 14-second engine run VTO (permitted for first 3 flights only)

FLYOFF FLIGHTS - 3 minute maxes

 All flights hand launched (VTO not permitted)

 Flyoff  Engine Runs

 Flight       Run (sec)

1                 10

2                                                   8

3                                                   8

 
 As Dan says it is a club event and has been pretty well supported and thrashed out over time.  No, the CD doesn't go around with a tach to measure rpm's and it is pretty well understood to be an honor system.  Most entries are indeed NOS models but there are several purpose built models as well.  The OS Max III .15 is pretty popular as it runs pretty fast and is a very tractable engine.
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Sandgroper
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« Reply #89 on: December 18, 2011, 12:27:28 AM »

Very sensible rules Randy I couldn`t see anyone objecting to those, the RPM rule sounds fair and the engine runs are generous  compared to ours- my OS Max111 .15 Dixielander on pressure and a 12second run would be nice-we have 10secs on suction.Here is the Dixie dressed up in Nos guise the NIB OS15 is the only Nos engine I managed to score online and it came complete with both venturis, also a Guillows Kiwi A Kit-original price on box$4.95 altho original docket has $1.95,sold from the Hobby Lobby S.Broadway,shame to build it but thats why I bought it.
A worldwide postal style contest for these models sounds like fun?we could have the event dedicated to a different modeler each year like the George Fuller Dixielander 50th anniversary contests.

Phil
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« Last Edit: December 18, 2011, 01:09:53 AM by Sandgroper » Logged
RobinB
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« Reply #90 on: December 18, 2011, 10:28:19 AM »

Phil, how does the MAX 15 III run without pressure?
What size tank do you use?

Robin
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Randy Reynolds
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« Reply #91 on: December 18, 2011, 11:32:38 AM »

MMM SLOP allows pressure.  I don't think I understand the rationale for not allowing pressure in this event.  Why legislate erratic engine runs?
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Sandgroper
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« Reply #92 on: December 18, 2011, 06:24:33 PM »

Hi Robin,
the Dixie has a 8cc hard tank,I will run it up today and see how it goes-I have two venturis 6.00mm and 6.50mm,prop is a 8x3 Master airscrew combat.I will use a pacifier in Open Power
Have you read the MMM rules for SLOP?-very interesting no engine rules  just a rev limit,It would be nice to fly an international postal Slop event sometime and finding a set of rules that everyone  agrees to is a good place to start.
Sorry I missed your point at first,I measured up the skinny Max111 venturi and it is the same as the 15la/fp, the  stepped 15 la/fp spraybar is slightly larger than the Max111 and too large to fit in,so yes the Max111 has a larger choke area than the 15FP?.I will make up a longer 5.0-5.5mm choke version to fit,the std insert fit in the crankcase is a little sloppy so i will kill two birds there.


Hi Randy,
keep the tank close and a stock venturi and there shouldn`t be a problem.Venturi size does not restrict power as much as you may think-my 15 LA breaks your 18,000 rev limit with 5%nitro a std venturi on a 7x4 and runs fine on suction.The diesels have a good fuel draw and don`t need pressure anyway.I prefer glows because of the faster warmup and have no objection to using pressure myself.
The no pressure rule and plain bearing engine idea was to keep out performance engines, the rev limit in your rules should achieve the same.
I am only thinking of a special event-that way we just pick a set of rules that every one agrees to and have a fun international event using the models we love to fly .
No one will need to change their own rules and yours look fine to me,just don`t be surprised if a SLOP with a PAW19 wins using VTO launch and a 14sec run.

Phil

« Last Edit: December 18, 2011, 08:17:18 PM by Sandgroper » Logged
Scottl0413
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« Reply #93 on: December 19, 2011, 09:21:15 AM »

Phil, you will like the way the Kiwi flys! I built one last year and mounted a Fox 15X on it and this year at the US Nats. took fourth place with it. I am going to build the 1/2A size for early nostalgia. Pic. attached.

Scott
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glidermaster
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« Reply #94 on: December 19, 2011, 11:24:22 AM »

Randy asked "Why legislate erratic engine runs?"

Running on suction doesn't have to mean an erratic engine run. To get consistency a modest intake size is required, and some good practices in construction and placement of tank have to be followed. All it means is that power output is kept in check, even though modern schneurle engines (even though plain bearing) are capable of much higher power.

I guess it does mean there isn't that much fun in it for the engine wizards, although some of the recent pictures would seem to suggest otherwise.

John
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Sandgroper
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« Reply #95 on: December 19, 2011, 06:13:25 PM »

Nice one Scott
is that  paper tissue or polyester? the Fox15X looks like a good choice- light and lively
Do you print up your AMA numbers?
Not sure how they will come out but I have attached a page of letters and shapes from Model Airplane News Aug 1960 to cut tissue letters numbers and stars with etc.
I was lucky to be given a boxfull of 50,60,70s American Modeler and Flying Models mags years ago and they have been very useful
I fold up the tissue tape it under a photocopy of this and cut through with a sharp knife and a steel rule to get multiples of my AUS numbers.

Phil
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« Last Edit: December 19, 2011, 06:48:36 PM by Sandgroper » Logged
Scottl0413
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« Reply #96 on: December 20, 2011, 09:10:15 AM »

Phil, covering is Polyspan with 4 coats 50/50 but. dope. I use Polyspan on open frames wings to get the rigidity required. Tissue works great also but sages when the dew is on the ground!! Numbers are lazer printed on self adhesive film. The tissue no.'s will work fine, I've used them on a couple of models also and they work and look fine. It's just very time consuming!! Pic. attached of tissue no.'s.

Scott

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Sandgroper
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« Reply #97 on: December 20, 2011, 09:33:19 AM »

True ,a mate of mine printed up all the 70`s auto stickers he needed to put on his 76 Holden Chev 327 Monaro to make it look era,I will look into printing some too.
The polyspan is tough stuff-I had a 400sq SLOP dt into the top of the only gumtree in the paddock.The farmer lent me his open sight 357 Martini rifle and a box of ammo and I managed to pop the branch it was on, the branch came down with the Slow 400 dting behind it undamaged.Put a 3.5 car motor in it later and didn`t it hoot then.

Bedtime here goodnight

Phil
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Sandgroper
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« Reply #98 on: March 24, 2012, 06:13:05 PM »

I found a nice SLOP engine the Brodak 15 plain bearing $80

http://brodak.com/engines/brodak-15-engine.html

Phil
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