Quote from: Ken Culbertson on July 03, 2025, 12:40:59 PM
Let me pass on what I did on my arf.  After replacing the bellcrank I removed the top ribs on the inboard tip.  I don't know what you will use so I will leave that to you.  I made mine so that the leadouts were above the C/L like they are on the ARF.  Before adding the adjustable box, find a 30+" arrow shaft and cover it with sandpaper.  Thread the forward leadout through the covered shaft and slowly grind the ribs away until you can get the forward leadout to the furthest aft position the leadouts could be with it pulled as far as it will go.  Biggest mistake in converting is to not allow for the leadouts to move without hitting something.  Make sure the aft is not hitting any ribs when the adjustable is full forward.  I think your BC is mounted behind the spar enough that this will not be a problem and the 4" will give you maby 2 ribe you don't have to sand.  You will have cut the center out of about 1/2 of the inboard spay, maybe more.  When you have it all cleared out get some stiff 1/16 x 1/8 and glue them vertically just behind where the back leadout passes through the rib with it in the full aft position.  That will replace a small amount to the crush strength from cutting the spar.

Good Luck - Ken

Thanks, Ken, for the means and methods as they will surely help. And I have removed the 3 upper wing tip ribs as you have done. I will reshape the wing tip airfoil once I have the wing tip slot installed.

But I was sort of inquiring the distance behind the CG to set the 'centerline' of the lead outs as a good zero point. Based on good flight performance, where have others set their lead out position on their Nobler ARFs?

So where is a good lead out position for a good flying Nobler ARF? The stock ARF has rudder offset and the C/L of the fixed lead outs is close to 2" behind the CG. I will be removing the rudder offset, and 2" seems way too far back.

Thanks

Colin

I am sorry, you were good with the 3/4 behind the CG starting point.  Maybe an inch.  My Noblers were a bit on the aft end of the range.  I think it is the design.

Ken

Quote from: Ken Culbertson on July 03, 2025, 05:18:06 PM
I am sorry, you were good with the 3/4 behind the CG starting point.  Maybe an inch.  My Noblers were a bit on the aft end of the range.  I think it is the design.

Ken

Thx much. I'll set it up for 1" for the eventual maiden. And that is the 'centerline' of the 2 lead outs, not the forward lead out.

Well, my Nobler ARF is starting to take final shape. All the more difficult mods/upgrades are complete and the wing and stab/elev secured. The CF pushrods and ball joints were a pain as there is not much room in the fuse since it's so narrow, especially towards the tail area. But patience (which I sometimes lack) and perseverance got me through it. The wing tip weight box was not that difficult to install. But the adjustable lead outs were indeed a pain (as others have said). Had to trim almost every rib with the larger and relocated 4" bell crank so the wires were not in contact with any balsa and operated freely. But this rib trimming exercise weakened a few of the ribs so I had to re-strengthen them. Not difficult, just time consuming.

On my Nobler ARF, I removed the glued-in lead shot tip weight, and added a Brodak weight box.

I have no idea how much tip weight was in the original ARF kit. Any info on how much tip weight to add to the box would be appreciated. I guess I could start with say 1 oz and go from there based on flight performance.

I also fly on Spectra lines, so being lighter I can usually get away with a bit less tip weight.

I do have a set of plans for the original Nobler. It suggests 3/4 oz, but not sure if the same holds true for the Top Flite Nobler ARF.

Thx in advance.

Colin

Quote from: Colin McRae on September 08, 2025, 04:57:58 PM
On my Nobler ARF, I removed the glued-in lead shot tip weight, and added a Brodak weight box.

I have no idea how much tip weight was in the original ARF kit. Any info on how much tip weight to add to the box would be appreciated. I guess I could start with say 1 oz and go from there based on flight performance.

I will usually glue in (not in the box) about 1/2oz on a plane this size then put another 1/4oz in the tip box for a start.  My last Nobler ARF came without any tip weight.  Barely survived the 1st flight.

Ken


I also fly on Spectra lines, so being lighter I can usually get away with a bit less tip weight.

I do have a set of plans for the original Nobler. It suggests 3/4 oz.

Thx in advance.

Colin

Quote from: Ken Culbertson on September 08, 2025, 05:29:47 PM

Not understanding 1/2 oz glued in and 1/4 in the weight box. Why not just 3/4 oz in the box?? It's all adjustable.

Colin

Quote from: Colin McRae on September 08, 2025, 07:31:15 PM
Not understanding 1/2 oz glued in and 1/4 in the weight box. Why not just 3/4 oz in the box?? It's all adjustable.

Colin

To save room in the weight box for weight.  Unless you build the weight into the ourboard wing, some do, it will need some weight.

Ken

Quote from: Ken Culbertson on September 08, 2025, 07:41:26 PM
To save room in the weight box for weight.  Unless you build the weight into the ourboard wing, some do, it will need some weight.

Ken

The Brodak adj weight box can store around eight 1/4 oz rectangular lead weights (2 oz). Hopefully that will be enough, especially with Spectra lines.

Colin

Quote from: Colin McRae on September 08, 2025, 07:49:15 PM
The Brodak adj weight box can store around eight 1/4 oz rectangular lead weights (2 oz). Hopefully that will be enough, especially with Spectra lines.

Colin

   With stock Green Box Asymmetry, the box alone with nothing might be enough. 2 ounces is not in the plan.

     Brett

Quote from: Brett Buck on September 12, 2025, 11:55:00 AM
   With stock Green Box Asymmetry, the box alone with nothing might be enough. 2 ounces is not in the plan.

     Brett

I didn't mean to imply I was going to put in 2 oz. I was just responding to Ken's comment.

I have an 'Original' Nobler plan, and it says 3/4 oz so I'll start there. And yes, the Brodak weight box (with bolt) does offer some weight benefit empty of lead. But I also installed a ply lead out guide which will cancel some of the weigh box balance.

To your point I did have a past profile model with the same weight box design. No added lead was necessary.

Quote from: Colin McRae on September 13, 2025, 10:53:54 AM
I didn't mean to imply I was going to put in 2 oz. I was just responding to Ken's comment.

I have an 'Original' Nobler plan, and it says 3/4 oz so I'll start there. And yes, the Brodak weight box (with bolt) does offer some weight benefit empty of lead. But I also installed a ply lead out guide which will cancel some of the weigh box balance.

To your point I did have a past profile model with the same weight box design. No added lead was necessary.

     My point was that the asymmetry in the wing, including the flap, is going to lead you to not needing a lot of tip weight unless there is a large mismatch in the materials from  inboard to outboard. The  asymmetry itself is not excessive but the inboard flap is larger than the outboard, which is not what we normally do, usually the areas match or the outboard larger.

    If the wings are truly symmetrical, then, usually you have to use A LOT of tip weight. Aside from that, the asymmetry is not a very critical parameter and you can trim the airplane to fly about as well with anything from nothing, to the proper amount (about 1/2" for the Nobler) to too much (1.5") as long as you know what you are doing and are willing to add tabs where necessary.

      Brett

Quote from: Colin McRae on September 13, 2025, 10:53:54 AM
I didn't mean to imply I was going to put in 2 oz. I was just responding to Ken's comment.

I have an 'Original' Nobler plan, and it says 3/4 oz so I'll start there. And yes, the Brodak weight box (with bolt) does offer some weight benefit empty of lead. But I also installed a ply lead out guide which will cancel some of the weigh box balance.

To your point I did have a past profile model with the same weight box design. No added lead was necessary.

   By "Original Nobler" are you talking about the Brodak kit? That has about 2" or so of wing offset, doesn't it? It will be pretty different from the ARF Nobler which is more like the Top Flite Green Box Nobler. I don't know how much weight they install in the ARF Noblers. The two I have for fun flying are as issued and I haven't seen the need for more or less, and never been into the outvoard wing on either as yet.  Have you checked on and measure the ARF tip weight as it comes in the kit? Just curious.
   Type at you later,
  Dan McEntee

Quote from: Dan McEntee on September 13, 2025, 03:57:34 PM
  Have you checked on and measure the ARF tip weight as it comes in the kit? Just curious.
   Type at you later,
  Dan McEntee

Just an antidote:  My last one almost destroyed itself on the first flight.  It had no tip weight from the factory.  I put in a weight box and adjustable leadouts after that.  1/2oz glued in and I think I added 1/4oz later in the box.

Ken

Quote from: Dan McEntee on September 13, 2025, 03:57:34 PM
   By "Original Nobler" are you talking about the Brodak kit? That has about 2" or so of wing offset, doesn't it? It will be pretty different from the ARF Nobler which is more like the Top Flite Green Box Nobler. I don't know how much weight they install in the ARF Noblers. The two I have for fun flying are as issued and I haven't seen the need for more or less, and never been into the outvoard wing on either as yet.  Have you checked on and measure the ARF tip weight as it comes in the kit? Just curious.
   Type at you later,
  Dan McEntee

The plan I have for the 'original' Nobler I did get from Brodak. But Brodak says their kit is an accurate duplication of GA's original Nobler and is OTS legal. And the plan does show the inboard wing approx 2" longer.

The Top Flite Nobler ARF kit has the inboard wing approx 1" longer.

I removed the lead shot from the outboard wing and installed a weight box. I have no idea how much weight was in the ARF as I had to cut out the lead shot 'bit by bit' and couldn't really weigh it. The Chinese in their infinite wisdom just made a soup of lead shot and epoxy and poured it into a balsa 'box'. Was difficult to remove being epoxied in. Luckily, the wing tip plate was plywood so was able to take a bit of abuse while slowly cutting out the lead shot.

The pics are of the before and after of the lead shot removal. And you can see the new weight box which had to go a bit more inboard near the last rib. To place the new box farther out would have taken a lot of surgery with limited space. Best I could to at my build skill level.

 

  There really is nothing in common between the "Original Nobler" and the Top Flite Green Box Noble or what some call the " '57 Nobler" other than George designed both himself and they look alike! I got a copy of his Original Nobler from George himself at VSC years ago and he explained a lot of the history. Basically there was his personal airplane, then the plan as presented in M.A.N. in 1952 and then the green box Nobler. Some of this may be explained in the 2 part article for M.A.N. that he did for the Nobler in '52. Most of the guys flying stunt in that era didn't often make elaborate plan for models, and they changed things on the fly. George was originally from Ohio, and after graduating from college moved to Texas to take a job. Top Flite contacted him about producing the Nobler as a kit and asked him to draw up a set of plans. There was some pressure on him to get this done because they wanted to have the kit released before the end of that year. George didn't have any plans in Texas and his brown paper drawings and what was left of the airplane was back home in Ohio. So he started from scratch, drawing from memory, and made some changes that he thought the airplane needed. I got the impression from listening to George tell the story that he was really less than 100% pleased with the airplane and thus the changes. He sent the plans off to Top Flite and then they made some changes in order to engineer the kit so it would fit in their standard box, more or less making the airplane a bit smaller to useless wood and facilitate production processes like die cutting and such. If you can round up all three plans to compare then you should see differences fairly easy.  I suggest thinking of each version as a stand alone design because they really are in my opinion.
  Type at you later,
  Dan McEntee

Quote from: Dan McEntee on September 14, 2025, 05:06:43 PM
  There really is nothing in common between the "Original Nobler" and the Top Flite Green Box Noble or what some call the " '57 Nobler" other than George designed both himself and they look alike! I got a copy of his Original Nobler from George himself at VSC years ago and he explained a lot of the history. Basically there was his personal airplane, then the plan as presented in M.A.N. in 1952 and then the green box Nobler. Some of this may be explained in the 2 part article for M.A.N. that he did for the Nobler in '52. Most of the guys flying stunt in that era didn't often make elaborate plan for models, and they changed things on the fly. George was originally from Ohio, and after graduating from college moved to Texas to take a job. Top Flite contacted him about producing the Nobler as a kit and asked him to draw up a set of plans. There was some pressure on him to get this done because they wanted to have the kit released before the end of that year. George didn't have any plans in Texas and his brown paper drawings and what was left of the airplane was back home in Ohio. So he started from scratch, drawing from memory, and made some changes that he thought the airplane needed. I got the impression from listening to George tell the story that he was really less than 100% pleased with the airplane and thus the changes. He sent the plans off to Top Flite and then they made some changes in order to engineer the kit so it would fit in their standard box, more or less making the airplane a bit smaller to useless wood and facilitate production processes like die cutting and such. If you can round up all three plans to compare then you should see differences fairly easy.  I suggest thinking of each version as a stand alone design because they really are in my opinion.
  Type at you later,
  Dan McEntee

Thanks Dan

I really enjoy reading up on all of this type of CL history. So very interesting.

I'm in the final stages of finishing my Nobler ARF. I decided to go with yellow to recover the wing to resemble military trainer colors. (Plus it will make the model easier to locate if crashed )

Plus, some new decals from Callie Graphics can't hurt. (The old decals that came w/ the ARF kit were pretty rancid!)

Colin

Quote from: Colin McRae on September 14, 2025, 03:27:33 PM
The plan I have for the 'original' Nobler I did get from Brodak. But Brodak says their kit is an accurate duplication of GA's original Nobler and is OTS legal. And the plan does show the inboard wing approx 2" longer.

The Top Flite Nobler ARF kit has the inboard wing approx 1" longer.

    As far as I was willing to research it, the ARF is a Green Box Nobler copy, with the exception of the flat stab (which some people would argue is a "aerodynamic change" that would be a deduction of Fidelity Points in classic. It's not legal for OTS, being far off the cutoff date.

   The 1" is a little excessive but not outrageous, but having the inboard flap area larger is going to greatly reduce the requirement for tip weight.

     Brett

I'm getting to the point where I will need to cut the various openings in the stock FG cowl.

Based on others past experience, what is the best tool and method to make the necessary cuts/openings.

Colin

I would suggest you STOP now and before proceeding, scrub the inside surface squeaky clean and epoxy another layer of glass cloth to the inside to add some more rigidity to it. As you make the cut outs, it only gets worse. I plan on doing that with my next one. Make sure you are completely finished with the engine installation also. I use fine tip markers and start with the opening for the head if it needs it. Start with the glow plug hole and gradually work out from there. Mark an outline and then work your way out to it slowly a little at a time. Test fit as you go. Get it centered on the engine and do the holes for the mounting screws. You may have to do a crude opening for the venturi during all of this. The front opening for the cooling air should be as small as possible at first. As you get the other openings close to finished size, you can do the cooling air exit and it should be twice the size of the inlet opening. The exhaust opening should be last and be generous with the clearance around the exhaust stack and muffler, at least 1/8" or a bit more. Then do whatever holes you need for muffler screws. The cowlingvtakes a lit of abuse on these and to make it last and look good it's worth the extra work.
  Type at you later,
    Dan McEntee

Quote from: Dan McEntee on September 23, 2025, 08:35:18 PM
I would suggest you STOP now and before proceeding, scrub the inside surface squeaky clean and epoxy another layer of glass cloth to the inside to add some more rigidity to it. As you make the cut outs, it only gets worse. I plan on doing that with my next one. Make sure you are completely finished with the engine installation also. I use fine tip markers and start with the opening for the head if it needs it. Start with the glow plug hole and gradually work out from there. Mark an outline and then work your way out to it slowly a little at a time. Test fit as you go. Get it centered on the engine and do the holes for the mounting screws. You may have to do a crude opening for the venturi during all of this. The front opening for the cooling air should be as small as possible at first. As you get the other openings close to finished size, you can do the cooling air exit and it should be twice the size of the inlet opening. The exhaust opening should be last and be generous with the clearance around the exhaust stack and muffler, at least 1/8" or a bit more. Then do whatever holes you need for muffler screws. The cowlingvtakes a lit of abuse on these and to make it last and look good it's worth the extra work.
  Type at you later,
    Dan McEntee

Thx for all the great suggestions, but back to one of the original questions. What is the best tool to be used to make the actual cuts when the time comes?

Colin

Quote from: Colin McRae on September 24, 2025, 07:33:15 AM
Thx for all the great suggestions, but back to one of the original questions. What is the best tool to be used to make the actual cuts when the time comes?

Colin

      I thought I had typed that part??!! Sorry. Use a small diameter rotary bit and Dremel tool. Using bigger bits and coarse cutting edges causes the bit to grab on you. The ones I'm referring to are intended to be side loaded, and have a diamond shaped look to the cutting edges. This chore might be best accomplished before joining the wing to the fuselage, in retrospect. Lot's of "on and off" of the cowling to check the fit.

    Type at you later,
   Dan McEntee

Quote from: Dan McEntee on September 24, 2025, 07:52:31 AM
      I thought I had typed that part??!! Sorry. Use a small diameter rotary bit and Dremel tool. Using bigger bits and coarse cutting edges causes the bit to grab on you. The ones I'm referring to are intended to be side loaded, and have a diamond shaped look to the cutting edges. This chore might be best accomplished before joining the wing to the fuselage, in retrospect. Lot's of "on and off" of the cowling to check the fit.

    Type at you later,
   Dan McEntee

Thx Dan

I don't have that particular Dremel bit but will pick one up.

Colin

I may be a bit too late but there were two things I did on one of mine that helped.  1:  Put some reinforcement on the motor mounts.  I put in a block of pine in the center section between the mounts 1/4" behind the motor to the firewall.  I added side strips that closed the gap between the cowl and the mounts.  2: With the motor mounted securely slide the cowl in place then add the motor spinner.  Tape the cowl to the spinner with an appropriate gap.  Now you can screw it in place including one in each side into the mounts.  It will be properly supported, and the spinner will align with the hole.  For the cutouts, I use the same tool as Dan.  Plug the venturi and exhaust and leave the engine in. Drill a small hole around the center of the nav and exhaust then cut away small amounts till it fits.  Remember, you have to be able to mount the muffler with the cowl already on.  Leave room for the screwdriver!

OR - forget the nightmare and build a wood cowl that will let you take it off without messing with the nav and muffler.

Ken

Quote from: Ken Culbertson on September 24, 2025, 10:41:09 AM
I may be a bit too late but there were two things I did on one of mine that helped.  1:  Put some reinforcement on the motor mounts.  I put in a block of pine in the center section between the mounts 1/4" behind the motor to the firewall.  I added side strips that closed the gap between the cowl and the mounts.  2: With the motor mounted securely slide the cowl in place then add the motor spinner.  Tape the cowl to the spinner with an appropriate gap.  Now you can screw it in place including one in each side into the mounts.  It will be properly supported, and the spinner will align with the hole.  For the cutouts, I use the same tool as Dan.  Plug the venturi and exhaust and leave the engine in. Drill a small hole around the center of the nav and exhaust then cut away small amounts till it fits.  Remember, you have to be able to mount the muffler with the cowl already on.  Leave room for the screwdriver!

OR - forget the nightmare and build a wood cowl that will let you take it off without messing with the nav and muffler.

Ken

I did reinforce the engine mounts per past recommendations. The reinforcement also provides a platform for the Sullivan flex-type 4 oz clunk tank.

I did incorporate two 2-56 size blind nuts into the engine mount area to attach the cowl with Allen head cap screws. 

I also strengthened the landing gear mounts as well as the tail wheel attachment.

I know the crap stock cowl will be a headache but I'm planning to stay with it. My build skills are limited and seems to me it will be difficult to cleanly incorporate a balsa cowl on this ARF model. Plus, my model will need a bit of tail lead anyway, so I need to keep the nose as light as possible. I'm going to power this model with the new Enya SS 35 EX BB ABC engine which is quite light (7 oz) since the case is sized around an Enya 25 size engine.

The upgraded controls (4" bell crank, CF rods and ball joints) operate super smooth.

Colin