Are we overpowering our Noblers?

[frank mccune]

    Hello All:

    Between three of us, we have 3 Noblers that we fly.  They all appear to be overpowered and fly too fast, 4 sec. laps.  A couple of guys like the speed and line tension but it just seems to be a sacrilege to fly these old timers at that speed.

    The engine choices have been OS  La .40, O.S.La .40 and an old 1970 OS.40 Stunt.  These engines appear to be too much power for the Nobler despite going to a 4" pitch prop.

    I was thinking of replacing the engines with an OS .30 Stunt or an OS .35 Stunt.  I have been told that these engines would not have enough power to fly the Noblers.  The Nobler was designed to be flown with a Fox .35 Stunt which is no powerhouse.  How much power do I need to enjoy flying a Nobler?  In 1976, I flew a Nobler powered by Fox .36 p.b. circa 1972 and had plenty of power  Perhaps I should try the Fox again.  I also have a  1956 OS .35 that is a sweet engine that would work well!

    Suggestions as to what lesser engine would perform well in a Nobler.

                                                                                                                        Tia,

                                                                                                                        Frank McCune

[Tim Wescott]

You need to find one of Brett Buck's really good rants about the difference between power-at-the-moment and available power.  If you find a good one, you'll find him talking about the difference between an engine that does pump out lots of power all the time and an engine that can pump out lots of power when it's needed.  In a really good BrettRant^TM you'll find mention of 700 square-inch airframes that fly at top levels of competition on everything from piped Schnürle-ported 40s to muffled 78s.

All of those engine choices should be good ones.  If the things are going that fast on 60' or 65' lines, then you need to work on slowing the engines down in a way that still leaves them ready to perk up in maneuvers.  Setting them up with the right-sized venturis, the correct props, the correct mixture and the right fuel should do the job.  Your goal is for them to be running "way too rich" (for an RC plane) in level flight -- get it right and when the airplane slows down the engine will actually start putting out more power, so you get power when you need it.

My suspicion is that you're simply running the things too lean, and possibly with too-large venturis.  I'd start by richening them up until you're getting 5-second or slower laps (assuming 60-65 foot lines), then verifying that they're staying at roughly the same lap speed throughout the pattern.  If the engines "run away" then you may want to adjust the effective venturi size downwards by piling up layers of nylon mesh (pantyhose or similar) on the intake, but without ever getting to the point where the engine starts to sag at the tops of maneuvers.

You may also want to ask about each engine: I'm pretty sure that a Thunder Tiger 11-4.5 prop is best for the 40LA engines, followed by the APC 11-4 or APC 11-4.5 -- but I have no clue what the best prop is for the OS 40S.

[Mark Scarborough]

OTHER OPTIONS,,
LA .25 and FP 25

as TIm said,, what rpm are you turning your engines at,, sounds like if you are at 4 second laps, with a 4 pitch prop,, you need to slow them down

[Tim Wescott]

OTHER OPTIONS,,
LA .25 and FP 25

as TIm said,, what rpm are you turning your engines at,, sounds like if you are at 4 second laps, with a 4 pitch prop,, you need to slow them down

I was thinking of mentioning the 25s, but if they've already got the engines in the planes they may as well run with 'em.  If the plane isn't goobered up with too much weight (i.e., if I didn't build it) then one of those 25s ought to work (not an old baffled-piston 25!).

Launch RPMs of somewhere around 9000 to 9800 should be good -- I launch my way-overweight Twister (53 ounces empty) at 9870 with a 46LA and a TT 11-4.5 prop and it seems to do well.  Different props, airframes, and engines will want different launch RPMs.

[Balsa Butcher]

All of the above is true. For a short answer: try the OS 35S if you have one. 10x5 or 10x6 prop. If your Nobler is under 45 ounces it will be a good match. As for the others-smaller venturi, less nitro, all the usual techniques of taming an engine down could be tried. 

[Bob Reeves]

I have a NobleARF with a ST 46, power doesn't have to equal speed.

[Brett Buck]

I have a NobleARF with a ST 46, power doesn't have to equal speed.

  In fact, it absolutely DOES have to equal level flight speed, if you are using the real definition of power. What stunt fliers consider "power" is something else entirely.

   The PP is *exactly* why I started the "small engine" experiments. If a 40 puts out twice as much power as you need, might want to try an engine half the size. Note also

4 sec laps = ~ 100 feet/sec
5 sec laps = 82 feet/second

   (100/82)^3 = power differential = 1.83, or it takes about 55% of the power to go 5 sec/lap instead of 4 sec/lap. .55*.40 = .22. How about that?

    Brett

[Motorman]

BrettRant^TM

You could make a fortune!


MM

[Bob Reeves]

  In fact, it absolutely DOES have to equal level flight speed, if you are using the real definition of power. What stunt fliers consider "power" is something else entirely.

   The PP is *exactly* why I started the "small engine" experiments. If a 40 puts out twice as much power as you need, might want to try an engine half the size. Note also

4 sec laps = ~ 100 feet/sec
5 sec laps = 82 feet/second

   (100/82)^3 = power differential = 1.83, or it takes about 55% of the power to go 5 sec/lap instead of 4 sec/lap. .55*.40 = .22. How about that?

    Brett

Please tell us how to explain the difference if not "Power" between two identical airplanes with different engines. Both doing 5 second laps, pull the nose up for a wingover.. One can barely make it to the top, the other just goes where you point it. I really do not know what term to use if I'm not allowed to use "power".

[Tim Wescott]

I have a NobleARF with a ST 46, power doesn't have to equal speed.

To clarify Brett's comment, the engine's power output when you're flying level doesn't have to come close to the engine's power when you're pulling a vertical line.  In fact, you don't want that.  You could probably fly an ARF Nobler, level, with decent lap times, with a 15LA or an Enya 19.  But the engine would be running flat out and there'd be no poop left when you pulled a vertical.  You'd complain because the engine power output does not change.

The whole point of a good stunt run is that the engine is loafing along in level flight but when you start doing tricks it starts pumping out more power (this is the whole actual verses available thing).  This is why the 2-4 break is valued on engines that do it, it's why you adjust the thing way rich (for an RC-er) on the ground before launch, it's why piped engines use pipes that are "too long" (for an RC-er), it is -- indirectly -- why engines "run away"*.  It's even why the electric guys use governers in their ESCs or timers (because as the plane slows down the motor loading goes up and power goes up), and it's what Igor Burger has designed into his system for "even more so" higher power output when you want it.

* Stunt engines run away because they're adjusted to fly at far below their optimum power output, at wide-open throttle, and still be able to put out more power yet at certain times.  If the engine isn't amenable to that treatment, or if you do it wrong (e.g. a high-pitch prop on a Schnuerle ported thing that wants to go fast), then the engine may hit it's high-output stride and stay there -- and we say it has run away.

[Tim Wescott]

Please tell us how to explain the difference if not "Power" between two identical airplanes with different engines. Both doing 5 second laps, pull the nose up for a wingover.. One can barely make it to the top, the other just goes where you point it. I really do not know what term to use if I'm not allowed to use "power".

Both are putting out the same actual power in level flight (half a horsepower, according to Brett.  I'm too lazy to disbelieve him).  One has more available power than the other.  Now pull the two planes into a wingover.  The engine with more available power delivers it, the plane it's attached to does a nifty wingover*, and you're done.  The engine with less available power delivers what it can (much less power), the plane it's attached to does a scary, slow, loose-at-the-top wingover, and you're done**.

So go ahead and use "power" -- just put the right adjective in front of it.

* or if it isn't it's not the engine's fault.

** except, perhaps, changing your shorts.

[Steve Helmick]

I would look at the line length right off. With .40's and .46's, you should be using something around 62' to 64' eye to eye line lengths. If you're flying on 60' lines because that's "traditional" (or something), you need to invest in some new ones.

As I recall, your OS H.40S has something like a .284" venturi bore. If the spraybar is .157", that should be about right or maybe .010"-.015" too large. That can be adjusted with the pantyhose or some other air filter (Bruline or R/C car foam sock style). You might look at adding a head gasket or two, especially to the .40LA. I don't know anything about the OS H.40S, but don't be afraid to experiment. I would not be shocked to find that the .40LA head gasket would fit the H.40S. Shims can also be made from beer or soda cans with some determined effort...or just check with Randy Smith or Eric Rule! I would definitely try the RSM 11-6 on this engine, and the 11-5 APC. 

Can you reduce nitro content to 5%? We would have to special order 5% fuel, so most everybody that still runs IC uses 10% for the simple reason that we can get it at one of the (few) LHS. I would not go below 5%...improved fuel economy tends to make the engines less happy. More fuel going through the engine means more oil is also going through, which means more heat is sent out the exhaust (and onto your model). Ah, that's real nostalgia for you!    Steve

 

[Dave_Trible]

Sometimes being outside the box and being a big proponent of 'big power',  using one of the hossier systems out there,  for your Noblers I'd take the tack of going back to smaller or more traditional engine choices for your planes.  My big power is controlled with precise pipe location,  needle setting,  finitely tweaked carbon props and a few other things.  Read that 'effort'.  Yes there are benefits but it's work sometimes.  You are sport flying Noblers.  Make it more fun and easy with engines best suited to this rather small but great airplane.  The .35S suggestion was good.  The old standard Fox is good.  I have a couple green box kits to build and I'm going to put the Fox .36 round Venturi in one and likely a McCoy .35 series 21 in the other.  Both have more and better power than the old .35 but have tame characteristics for normal stunt runs.  You can sure fool around with what you have and occasionally get an acceptable run but it can be simpler and more consistent with a more turn-key power plant.

Dave

[Dan McEntee]

   To put it simply, your Noblers aren't over powered, they are probably over propped. Guys have been flying these with .40 and .46 size engines for ages very successfully, and the gent from Australia who came to our NATS had one with a Randy Smith .61 in it, I think? Even powered with a Fox .35 or OS.35S you can over prop those engines and get lap times too fast on 60 foot lines. Having extra power is like extra money, better to have it and not need it than to need it and not have it! I have flown OS LA and FP .25 powered models quite a bit, and while you can get one to fly a Nobler ARF, it would be on a ragged edge and you better hope the wind don't blow! With a combination of the right prop, right line length, venturi diameter, fuel and glow plug, you can dial in the speed you are comfortable with.
   Type at you later,
    Dan McEntee

[Chris Wilson]

 If the things are going that fast on 60' or 65' lines .............

Bingo Tim!

I am bettin' that the lines are shorter than that. 

[wwwarbird]

 This is what the needle valve is for.

[Mike Griffin]

I watched Bob Dixon a club mate of mine when I lived in Georgia wi  contest after contest after contest in expert with an old red nobler and a fox 35

[Mike Keville]

You might want to ask Australia's P.J. Rowland, who stuffed a .61 into the nose of his Gieseke Nobler and did rather well with it at the U.S. Nationals a few years back.

(No word on prop/fuel combo.)

[goozgog]

   My fat 1952 Nobler flew as well as would
be expected with a LA.46.  (APC 12.5x 3.75)
Too fast for the 55oz air frame or too slow
for a decent engine run. OK for sport flying
but not good enough for competition.
I had a choice between a happy engine or
a happy airplane.

 I recently had a practical experience of
"The right engine for the right airplane".
  I installed my Ro-jett .67 in a Stiletto 660
knowing it would give me a superb stunt run,
and it did, but it turned a usable plane into
a piece of @#$%^&!!!.
To much unusable power.
 

   Len Bourel took pity and passed me a Tom Lay
ST.V.60 that dropped right in. (Rev-up 13-4)
  The difference was instant and amazing.
The Super Tiger runs happily in a RPM range
that the Stiletto can use.
For some reason I'm even getting a clean cut off
that eluded me with the Ro-Jett.
I dunno.

Anyway - Lesson learned.

[John Boys]

You might want to ask Australia's P.J. Rowland, who stuffed a .61 into the nose of his Gieseke Nobler and did rather well with it at the U.S. Nationals a few years back.

(No word on prop/fuel combo.)

Engine is a Stalker .61 with rear muffler. Appears to be a carbon prop and spinner. PJ has competed very successfully in both Classic and F2B with this model.

[José Almeida]

Hi.

Not necessary at all!

I have the experience with two 52 Noblers and had different results.

One use the Fox 35, following all informations about construction and engine advices and don't have sufficient results for told this is what really expect.  
By other side in second 52 Nobler I made my own improvements and the results are completely different and have a competitive model for all competitions.  

This not mean that others opinions posted is not goods.

With this only want sharing my experience with Noblers without overpowering like P.J. Rowland from Australia with a Stalker .61!  

Always fly with my planes between 5,2 to 5,4 seconds/lap. I like flight relaxed and enjoy the beauty of flight and model. I don't like flying below that. For me less than 5 seconds/lap is not Aerobatics. Speed flying is for combat, speed and carriers.

Many combinations are in the market for use between .25 and .40 without overpowering.

Mine is an OS Max 32 from Randy Smith with Hunt pipe. I join two ages of time and the result is amazing.  

I use ByO 11X4 at 11.000rpm at ground with home made fuel, 11% Castrol M/11% Syntetic Micro Motul and 5% Nitro. Thunderbolt glow plug and pipe pressure.

The Nobler have 1170 grams and fly with 60' lines .015.

The only difference is I up the wing 10 to 12mm and put the engine at 8 o'clock position.

Regards

[Steve Riebe]

I toned mine down a little, running a FP40 with an FP25 venturi and a Randy Smith spray bar and needle. I fly with 62 foot lines and a Xoar 11-4 prop.  It seems to work well for me, but I'm no expert and fly only the beginner pattern.  This plane started out with a Brodak 40 but was uncontrollable due to the shaft bearing was worn and going over lean.  The main reason I run the Xoar prop is I couldn't make an APC prop fit in that small 1-3/4" spinner with it's large hub size.

[Bob Reeves]

I toned mine down a little, running a FP40 with an FP25 venturi and a Randy Smith spray bar and needle. I fly with 62 foot lines and a Xoar 11-4 prop.  It seems to work well for me, but I'm no expert and fly only the beginner pattern.  This plane started out with a Brodak 40 but was uncontrollable due to the shaft bearing was worn and going over lean.  The main reason I run the Xoar prop is I couldn't make an APC prop fit in that small 1-3/4" spinner with it's large hub size.

Started flying Intermediate using a Twister with an FP 40 set up close to what you are describing. The thing was so choked down to keep it from running away it was almost impossible to fly in any kind of wind. At one contest in GA it wouldn't do the clover without getting blown out of the first loop. My solution ended up being a Saito 40 which helped me get to the middle of Advanced with the same Twister.

Maybe the proper term is "controlled power" ?? To me it's still all about power however you get there.

[Dick Pacini]

How about the EVO 36 or the Brodak 40?

[proparc]

I have a NobleARF with a ST 46, power doesn't have to equal speed.

That is EXACTLY the setup I would go with.

[Scott B. Riese]

54 oz 5 oz tank LA-46. 62' .015, laps at 5.15, 9300 rpms Prop has been changed to a Bolly 11.2x 5.2 GLASS 3 bld. Killer set up. This is the 1968 Nobler from BOB'S Plans

[Garf]

The Brodak .40 is perfect for the NoblARF. Next would be the OS 35 with the ABC aftermarket P&C assy.

[Target]

I have an os 40fp on my Banshee. It has adjusted timing, less compression, and a smaller than stock venturi. Starts nearly always on the first flip, and works the 4 2 4 run perfectly without a burp.... I believe we are running an 11-4 wood prop on it, forget which brand.
But the plane isn't fast or over powered, and I'd think this would also be fine for the Nobler.

[Andre Ming]

"Are we overpowering our Noblers?"

Compared to their original intent and construction techniques: Absolutely.

In view of the new intent and ways of constructing things: Probably not.

However, I'm a vintage combat plane guy... so the above is pretty much useless input!

(But it felt so good to type it.)

[john e. holliday]

Right now my EVO is on the nose of my ARF Nobler.  Just for break in as fuel tank is not big enough.   Had to add tail weight to get it to turn like I want it.  But, I say for the Nobler a well broken in Fox .35 Stunt is the ticket.

[wwwarbird]

 Hello? Frank? 

[frank mccune]

    Hello All:

    I have been advised to post more information about how we are flying our Noblers.  I do not like to advise another flyer how he should set up his plane/engine for better performance.  For this reason, I have not suggested to go to less pitch in the props and richen the mixture.  Most if not all, other flyers are smarter than I and have more experience.  It is like giving advice to a bird hunter about how to train and handle his dog.  A very touchy area where I will not tread.

   The Noblers doing 4 second laps are just about as fast as our Foxberg Racing planes went in the early 80's, 27 sec. for 7 laps was the norm.  These other guys like to fly fast so who am I to suggest that they are incorrect?  Me, I like to go as slow as possible but have good line tension at all times.  Slow is good!

    I have the following engines and airplane combinations that work very well for me.  That is that they start first flip, 4-2-4 perfectly and have good line tension.

    Midwest 109 with OS .35Stunt 10X5 prop

    Magican with 1972 Fox .40 Stunt 11X6 prop

    Twister with HP .40 11X5 prop

     Nobler with OS Max H .40S 11X6 or 11X5 prop

     I removed the mufflers as our new field does not require their use.

     All of the engine are set to 4 cycle in level flight and break into a 2 cycle when pulled into an maneuver. The lines are .015"X 60feet.  Fuel is GMA 10 22 with an additional 6 oz. of castor added to the gallon.  Perhaps I should use a mix that has 27% castor in the older engines but I do not know what correct fuel is anymore. I have always run 5-10% nitro and 27% in my engines but I got some different fuel to try. I will go back to a 5% nitro, 27%caastor to determine if it provides a better run.  The GMA fuel worked very well in warm weather.

     I hope that this additional information helps in understanding what we sport flyers are doing.

     One question remains: Are the new OS engines ok too be run in a 4 cycle mode? I was informed that they should only be run in a wet 2 cycle mode.  This is how I see them run thus the speed.

     I hope that this information helps explain what we Sport flyers are doing an may be an aid to other novice flyers.

                                                                                                                 Be well my friends,

                                                                                                                 Frank McCune

     

[Tim Wescott]

Hey Frank:

You won't hurt a 40FP or a 46LA by 4-stroking it, but you won't be using it to it's potential and it'll really want to run away on you.  That's not the story if one has been retimed -- in that case, it may well work in 4-2 mode, but it won't ever put out as much peak power is it could formerly.

I'm pretty sure that all the engines you mention using are older baffle-piston engines.  If so, then 4-2 mode is probably right.  If some guy named Randy Smith or Brett Buck contradicts me they're right, but I think that your your engines you want to stick with roughly the same prop and 4-2 break, but go to smaller venturi size (or piles of nylon net on the intake) until your lap time goes down to where you like it.

At least with the OS LA engines and the Tower 40 that I have, the venturi-size tradeoff seems to be between a propensity to run away (when it's too big) and a propensity to sag (or not pick up) in maneuvers.

[Chris Wilson]

Put the mufflers back on?

[john e. holliday]

Yes, take it from some one who is having surgery on his ears,  use the mufflers.   Last time out they said my Ringmaster Imperial was doing 4.4-4.6 laps in level flight.  But that is where it feels comfortable for me.

[Tim Wescott]

I should have linked to these before.  Read what Randy has to say in these threads:

http://stunthanger.com/smf/index.php/topic,15595.0.html,
http://stunthanger.com/smf/index.php/topic,4037.0.html, and
http://stunthanger.com/smf/index.php/topic,27257.0.html.

[Paul Walker]

Overpowered, no.

I once upon a time flew a 45 ounce Imitation with a SuperTiger 60. With the right prop and venturi it flew great, and not at 100 mph.

The problem is in the prop and venturi. Get those right, and it will fly slower and more controlable.

[Walter Hicks]

You might want to Really Listen to Paul Walkers Post!!!!!!!!!

[Air Ministry .]

The oil 205 castor ( good stuff 0 3 % Syn. unless its up around over 30 degrees , where the 27 % might be good . Not in winter .

Nothing like a unmuffled ship with the motor barking and snapping as it follows the bumps in the air turbulance on a windy day .
You sure know its hooked in and doing its job without having to look , or have it catch you out .

You need a Fox 59 , 1958 if you want them to hear it in the next valley .