ARF Nobler power revisited

Has anyone tried an OS LA 25 in the ARF Nobler? We are leaning toward the 25 instead of the Fox 35 we had originally thought we would use mostly because of the ease of operation with the LA 25. The 25 would also work well with the tank provided in the ARF and the LA 25 we have runs better than any of my stock box Fox 35's.

IMO the LA 25 would be more user friendly than most Fox 35s and at least equal in power but again, the creme de la creme for this model would seem to be the Brodak 40.
See my previous posts on fuel consumption. If it holds 3.5 oz it should be good to go with the B 40. Mounts may take a little widening from what I have read to fit the slightly wider B 40 case, though the case is the same width as the LA 40 for which the airplane is supposedly designed.
If no B 40 is available to you go with the LA 25 first choice, LA 40 second choice, Fox 35 third choice(or wait until you can get your hands on a B 40)

I agree: B40 is the engine of choice. I've also seen OS 35FP that looked like a real good match too. All 4 Noblers at Northampton meet had motor sizes between .35 and .40.

Whoa, Steve - that's one mean-lookin' smiley!

Tim

>Whoa, Steve - that's one mean-lookin' smiley!
Here, you can have it too:

[photo not recovered: 3f2ebb0722f67d9e.gif]

Just place the following in your avatar settings: http://clstunt.com/htdocs/dcforum/User_files/3f2ebb0722f67d9e.gif

Nah, I don't ever want to be that scary... I'll just stick with my harmless old Flite Streak...

Tim

>Nah, I don't ever want to be that scary...
How about this one?

My B 40 was a perfect fit, barely snug in the mounts.

>My B 40 was a perfect fit, barely snug in the mounts.

I have a few here if people are interested.

Ty,
Will your Nobler fly the complete pattern with the B40? If it will, what mods were made to the airplane if any?

Oh yea I would still like to know the original question. Has anyone flown a AFR Nobler with a OS25FP in the nose.

Leonard how much are you getting for the B40 engines.
Thanks,
Mike Clark

Mike,

Alan Hahn is powering his ARF Nobler with a Brodak 40. Alan, Owen Richards and I have all flown complete patterns with Alan's plane. The engine seems to be a perfect match. Alan thinned and trimmed an 11X5 Zinger (I don't know the final dimensions) and the engine runs in a solid 4-stroke, only breaking in the overheads and clover. A great combination.

Fred

LAST EDITED ON Aug-06-03 AT 11:25 AM (CDT)
 
Is it using the stock tank?

I have a Brodak-40 in a more or less Oriental and it needs 4 ounces for the pattern. I removed a 3 1/2 ounce tank because I was running out of fuel in the overhead 8. I am running an APC 10.5 x 4.5 in a fast four-two-four at 5 second laps on 58 foot eye to eye lines. The engine is well broken in so I don't think the fuel mileage is going to get any better. Great engine, plenty of power..

Edit: I am running 5% nitro

HI Mike. My Nobler is not finished. I am installing a Brodak fuel tank in it. To do so, I cut away part of the "firewall" so it would slide in. I also placed a small carbon fiber rod over the push rod from the flaps to the elevator. I am finishing/repairing five planes at the same time, so each one is getting only partial time. busy, busy, busy.

>Leonard how much are you getting for the B40 engines.
>Thanks,
>Mike Clark

I didn't really want to make this a commercial (maybe I should just post it in the classifieds). As of right now I have four left of my allotment (Next batch due in December). Selling them at regular prices.

Wouldn't it be wonderful if there existed some way to actually compare engines on some fixture that would give meaningful numbers for the way we run stunt motors. If such a device existed we could not only compare engines, think of what we could learn by comparing props on the same engine. My limited understanding is that static thrust isn't a good measurement and horse power is just about as meaningless. Flying the same plane with two different engines is to subjective..

So how come the rocket scientists and engineers have not came up with a test device that will give us some numbers that mean something?

I have read several times that the FP-25 will fly a Nobler size airplane but have yet to see anyone fess up to actualy doing it.

>Wouldn't it be wonderful if there existed some way to
>actually compare engines on some fixture that would give
>meaningful numbers for the way we run stunt motors. If such
>a device existed we could not only compare engines, think of
>what we could learn by comparing props on the same engine.
>My limited understanding is that static thrust isn't a good
>measurement and horse power is just about as meaningless.
>Flying the same plane with two different engines is to
>subjective..
>
>So how come the rocket scientists and engineers have not
>came up with a test device that will give us some numbers
>that mean something?
>
>I have read several times that the FP-25 will fly a Nobler
>size airplane but have yet to see anyone fess up to actualy
>doing it.

What you are describing is a classic test stand that can measure engine torque versus RPM for a given prop and fuel combination. Peter Chinn published such data frequently in the old Aeromodeler whenever he evaluated an engine, in the form of a plotted torque curve. The engine has to be mounted to a torsion balance that will allow the torque at the crankshaft to be measured by the deflection of a pointer due to the twisting of a spring (old fashioned) or the force exerted on a strain gauge (newfangled). Power output = Torque X (Angular Speed of Crankshaft). Rubber flyers use a piece of piano wire with a pointer and scale to measure torque ("torque meter"). I recently saw such an engine test stand advertised in Flying Models, IIRC. It certainly can be done. One last wrinkle is that this is still a *static* measurement, and cannot account for the change in load at the crankshaft due to the movement of the prop through the air in flight ("unloading"). But it does allow comparison of relative performance for various setups. One step simpler is to mount the engine to a sliding mount and use a spring scale to measure thrust as a function of RPM. This is easier to do, and could again allow for some meaningful comparison between setups. It might demonstrate the RPM range where the prop is working most effectively with the engine, to produce maximum thrust, for example. Certainly the inexpensive little hand-held tachometers make the engine RPM measurements easy enough.

FWIW,

I am using a 4oz clunk tank, and now have no trouble with finishing the pattern with the tank, with approximately 10-12 laps left over. The Brodak 40 has definitely gotten thriftier with fuel over the last ~20 flights.

Andrew,

One difficulty with power and engines is that thrust matters too, so a high reving engine might be making more power, but not necessarily more thrust than an old slower turning engine with a bigger prop. I think the real test is putting the engine in a plane and finding the prop which produces stunt "nirvana". I have no doubt that someone will be able to fly the Nobler with the LA25, it is just that the Brodak 40 is a really beautiful match.

However having said that, I think I may need to add more prop to the load (currently using a thinned 11-5 Zinger). For the engine to feel comfortable in the verticals, I need to fly 4.9 laps (otherwise it is running so rich at 5.1 laps, that it doesn't lean out enough for me when I point the nose vertical). I may start with a Zinger 12-5 and thin and trim it down. But in any case, the plane is really flying nice.

I've been kinda waiting to hear from somebody running a 25. I also plan on using a Thunder Tiger Pro .25 (ball bearing) with stock muffler along with the stock tank. Should be a lot more power then a FP25/LA25, but I guess I don't want to be the Guinne pig. How much lighter is the Brodak 40 vs. a FP40?

Many years ago here in Northern California we flew Western Associated Modelers (WAM) sanctioned events that included engine classes for stunt: 1/2A, A (up to .20) and BC for the big boys.

At that time we used Veco 19BBs in lots of airplanes that were intended for .35s. Some of the best were the Sig Banshees and Twisters, the Jetco Dolphin and several flew Gieseke Noblers with them. They flew very well. In fact, this was our first introduction to low pitch and high RPM operations using four pitch props pretty much peaked out. Many of these planes felt solider than the same designs with .35s running classic 4/2/4 runs.

I would think that the modern schnerle .25s like the FP and LA OS's would do just fine. Only secret is to watch the weight closely which doesn't sound like any problem with the ARF Nobler.

LAST EDITED ON Aug-08-03 AT 00:16 AM (CDT)
 
The FP 40 is about 8 Ounces, without a muffler. The Brodak 40 is about seven, and so is the TT Pro 25BB, maybe a little more. The FP 40 had a "harsh" power curve that was perhaps weaker in a four-cycle than the pre-Schneurle engines, and a comparatively sharp break that made it difficult to use for folks who'd been programmed to expect a classic 4-2-4 as an ideal aerobatics operational mode.

The Brodak engine has a variation on the classic mode, being willing to run through most of a pattern happily without breaking from the four- cycle except for the last four maneuvers, when it's way up overhead. I never knew that the FP would do anything similar (and yet the H-40's from OS did so quite strongly).

My current FP 40, same as the prior one, wants to run fast enough in a two-cycle that even with 4" pitch props it's pulling planes around at "very quick" lap times when set for a wet two. It's not that heavy, and doesn't seem to give away as much low end grunt in the last models as seemed true in the earliest of them. I've been playing with this one running in a four stroke, too rich for it to break, and could use a hair more power, perhaps, but it's chugging along very smoothly, making me wonder why I avoided the type so long after the iron piston version was so comparatively unsuccessful for me, but I never tried it again after the changes.

If the FP 40 has a relatively unusable 4-2 break, and is so relatively fast in a wet two with 4" pitch props, the TT 25BB is going to need 3" pitch props (does anyone make 9-3's?) That suggestion is based on a lot of experience running the OS Max 25BB's that started the clone trend, and on which the Pro series are based. Mine are generating their most usable (for combat, anyway) power at 17,000 rpm's and on up from there to 19-something in the air.

(Yes, I did acquire at least one 11-3 APC to experiment with, but I'm having fun right now running it nice & slow, with a 10-4 APC.)

.
Kiwi

APC makes an 11-3, and both Graupner and APC make 10-3's, but nobody makes a 9-3 that I can find. APC might, if they were asked, or you can depitch a 9-4 or trim the diameter of the 10-3.

Pat Johnston built & flew a '57 Nobler with a .25...FP, I think. Of course, it was very light. He has also been flying a Magician with a .25 LA. I think it can be done, but I don't think I would like it. My flying style (if you can call it that) doesn't conserve energy, and thus demands lots of umph up front. Small engines work fine on big light airplanes in ideal conditions, but when the weather gets windy, there is no substitute for lotsa power. Steve

As I said earlier in my original post I have been tempted to try the LA 25 on the ARF Nobler but after a recent E-MAIL from Kaz Minato I think I will pass. Kaz said that he lost his LA 25 powered Nobler because it lacked sufficient power to fly well in the wind. Kaz has the LA 25 powered Nobler listed at 1200g on his web page, which I believe is around 41-42 oz. Kaz strongly suggested going with a more powerfull engine for the Nobler.

Ok...so you math wizzes out there: How many R.P.M. would a .25 need to turn to do 5.1-5.2 sec on 60' lines? Would a 10x3 work on the T.T.Pro .25 ball bearing?

Mark,
I have almost given up trying to figure props. On a Ukey 35 with an LA25, I was running an APC9-4. It pulled the plane fine, didn't sag, but was a little too fast--especially in the outside square (aka "dive of death"). For the heck of it, I changed to an APC 10-3 (a BB recommended prop), expecting an airspeed that would be glacial. I was pretty surprised that the plane flew a little slower than with the 9-4, but nowhere's as slow as 3/4 (the pitch ratio). The launch rpm was similar in both cases~12krpm. I kept the 10-3 on since it seem to make the "dod" a little slower.

In the end I came to a conclusion that you should just try different props, and not to use any preconceived bias--at least within reason.

Alan, what did you do about the "lead-out problem"?

Chuck,
If you mean the Nobler, I just cutoff the old cables and put in new heavier Sullivans. It was easy to feed the new lines down the wing, and the bellcrank easily comes out. However I did leave on the wire clips. Sort of wished I'd taken them off now, since they have a tendancy to jam up on the bellcrank. Of course it is pretty easy to take off the wing (I didn't glue it in, and have already done it once) and clip them out, but then I'd have to remake the lines, and I am just too lazy. I will probably regret that.

Otherwise the plane flies pretty good, with the fixed leadouts and wing weight. Of course I'm not expert enough to distinguish any subtle effects.

I started assembling my ARF Nobler today, and it is about engine selection crunch time. After weighing all the components plus a Fox Stunt .35, I came up with 40 oz. total. I did not include fuel lines and filter. I am guessing that all that epoxy and the fuel system components will add another 2 oz. of weight. I have a .40 LA that I bought for this model, but I reslly want to use the Fox. Will the Fox fly it at 42 oz.?

My Oriental is closer than I would like to being 42 ounces, and a high-time GMA ABC Fox 35 pulls it along just fine.

The real question is how strong your Fox runs. I would want to be sure it is a real good 'un before going to the work of installing it in an ARF Nobler. Especially when there are so many good engines out there now.

For what it's worth, my ARF Nobler will be fitted with both a Fox 35 and that Magnum 36 PTG forced me to buy. Gonna whack off the stock beam mounts at the firewall and use plastic (RC) radial mounts in order to make this a fairly painless operation.

I don't really know how strong my Fox is. It is new except for break using Kiwi's method.

Your Fox is probably ok. I remember reading George Aldrich's original article on the Nobler and he talks about weights ~47oz. Now George was a master, especially at flying real slow, so I am not sure how much of his experience can be translated to my skills.

I think the main thing is making sure your Fox is well broken in and that you are using the recommended fuel ((10% nitro, >25% all castor lube). If you use a muffler, make sure it is as light weight and unrestrictive as possible. If you are folowing Kiwi's instructions, you are probably be just fine.

I have a flying buddy who pulled out his old Green Box Nobler (from his teen age years), plopped on a Fox 35 that he had been using in Foxy Hazel (aka Fox) Racing, and it really ran like a champ. I bet his Nobler was heavier than the Nobler Arf.

>
>For what it's worth, my ARF Nobler will be fitted with both
>a Fox 35 and that Magnum 36 PTG forced me to buy. Gonna
>whack off the stock beam mounts at the firewall and use
>plastic (RC) radial mounts in order to make this a fairly
>painless operation.
>
>Dan Rutherford

Dan;

Are you going to reinforce the firewall?

Dan,

I decided to go the 'painful' method, so I reinforced the the front end. I didn't like the mounts just hanging out there by themselves, so .........., cross-grain balsa between the mounts, all the way back, plus laminated gussets in front lap-jointed to the fuse. Not much weight gain and it's now quite solid. I put in a slight amount of offset.

The primary engine will be an OS35S. The mounts are also drilled for a Magnum 36 (experiment). Both engines have bench time and the OS is also used.

I designed a larger tank (4.5 oz) for it as most of the engines will need at least 4. I made 2, so hopefully Alan will be trying one this noon. If it works well, we'll report that and provide info to the forum. If it doesn't...don't ask (back to the drawing board)

Fred

LAST EDITED ON Aug-15-03 AT 12:03 PM (CDT) by ()
 
Hey Fred,
That picture of the top of your mounts with all that metal reminds me of one of those James Bond villians, the one real tall guy with the metal teeth!

For what it's worth, I didn't even bother with blind nuts. Since the cowl is removable, I just used normal nuts and washers, with some Locktite (blue) to keep the bolts from unwinding. That way I kept as much wood as possible. I suppose the true test will come if the engine pulls out of the mounts, or I prang it.

Fred,
That looks very nice, and much more substantial than the stock setup. I don't look at the ARF Noblers and Flitestreaks as being disposable, and am trying to build mine to last a long time.

LAST EDITED ON Aug-15-03 AT 01:56 PM (CDT)
 
Back to the drawing board.

The tank seemed OK until the end manuevers. During some of the end manuevers, there was enough fuel shift to cause engine cutout. 1+ oz. left at the end. This tank is quite deep with an offset wedge to keep the pickup at spraybar height. I'll work on some options to keep the tank height at a minimum and closer symmetry. Possibly a quare tank with some type of captive sump or a 4+ oz pinch-corner tank. I run a pinch-corner tank in my Mustang and it seems happy for the entire pattern.

Fred

Bob,

I am assuming the firewall will be reinforced with my use of radial mounts. Too easy to do, too light, too much benefit to avoid a few moments in fitting the pieces.

I have been away from the RC game too long to know for sure, but I seem to remember at least one brand (Kraft-Hayes, now just "Hayes"?) which used a common drilling pattern for a relatively wide range of mount sizes. Or more specifically, the size engines to be used in the mounts. Thus it may be possible to have mount/engine combination ranging from the 25LA, Fox 35, Magnum 36, possibly even small-case 40s.

Sure, leave mount attached to engine. If the holes in firewall match all the mounts, no problem in switching around. Okay, the cowl would get severely cut up during these trials--no one should ever be caught flying a Nobler without the cowl in place--but I believe replacements are available.

The forty size nylon mount is too wide to fit, I haven't tried the next smaller size.. I had given up on the R/C mount idea as I was thinking R/C mount with .25 engine rotated so a Mac muffler/pipe would exit out the bottom, looks like to much work for pipe to clear

Larry Cunningham uses a recessed 1/8"aluminum pad on hardwood mount with engine bolted to the aluminum pad and that bolted to hardwood mount, change engines, change pad.

Fred, are you gonna bring the Nobler to Rockford?

Yes Fred, Are you going to bring the Nobler to Rockford?? Inquiring minds want to know!

I'd like to have it done by then. If I don't have the time, I'll just bring the fuse along so people can see (critique, criticize, etc.) the front end reinforcement.

Ha Ha ........nice try Alan! You know me TOOOO well. 2 years on the KA-10 and STILL holding!

Fred

I should have my Nobler ARF ready and at Rockford and unlike Fred you'll have to wait until AFTER I fly to see the insides of my plane. And the way things have gone this season, you will get to see the insides of my plane.

When anyone puts an LA 25 in one of these airplanes will you start a thread and tell us how it goes?
Hi Mark.

Hey Chris,

Hows the racin' going? It looks like I'll be the one to try a 25 set up, hopefully done by next week. I'm using a Thunder Tiger PRO .25(ball bearing) which I think (hope) should be good for another 1000 rpm over a FP25 and swing a APC 10X3 on 58'lines at 5 sec. lap times.
My thought is:
I have engine.
Appx. 1oz. lighter then a 40.
Stock muffler is adjustable to direct exhaust away from monocoat.
Use the 3.5 oz. tank that comes with kit.