EDIT BY RC STORICK Take-apart can be viewed here--->http://stunthanger.com/smf/index.php?action=gallery;cat=22

Here are some emails that I received from Ed Prohaska explaining some of the Photos of his "take apart" ARF Nobler.

Hi Hoyt, My name is Ed Prohaska. Due to some very rough decades I'm 59 years ooooold and feeling every days of it! I attached 12 photos. They are a mix from the 3 Noblers I completed and the 4th one still in progress. I have lots more but don't want to "blog" your computer. With the ARFs, I often use the time saved  in framing and covering to try new ideas, that I otherwise would not live long enough to try. I did 2 of them (#2 and #3) for other club members who paid me for the service.

I installed a second plywood former at the wing LE and reinforced it as shown in the photos. My main concern on the first one was strength and safety, rather than weight. In the front I used two 4-40 bolts, a plywood key-way and a dowel on the first 3 wings. Later, we tried flying 2 of them without the front bolts and it was OK, so I'm omitting them on the 4th one. The key-way plugs into the square hole that's already in F-2. It makes a snug fit and really locks in the front end to resist torque forces and absorb vibration. I don't think a single dowel would cut it here, unless the engine ran especially smooth and the wing saddle was very tight.

All models have maple blocks in the rear, with 6-32 socket head bolts and threaded inserts. These replace the ARF's very long 4-40 bolts, blind nuts and ply 'bridge" which I remove. The bolts pass through reinforced "pillars" in the wing trailing edge (usually glass or carbon push rod stock) to prevent crushing of the balsa T/E structure. The bolts rest on a 3/32" plywood plate. I glue the blocks in with 30 minute epoxy, thinned slightly with lacquer thinner and heated with a Monokote gun to soak it into the wood. These joints are more than strong enough to hold the wing and fuselage together in a .60 size or larger model.

After gaining experience on the 1st one, I was able to reduce weight on the next 2.  Nobler #1 weights 51 ounces and flys well at that weight.
The 2nd one (only the wing comes off) weights about 44 ounces. The 3rd one is fully take-apart and weights 47 ounces. As you might expect, the lighter ones fly a little better (tighter corner and less "tug" on the lines), but all 3 fly well.

The main advise in doing a take-apart is: SAFETY FIRST!  That's why my first one came out heavier than most one-piece models and a few ounces heavier than subsequent take-apart Noblers. My main goal was to make sure it would stay together in the air, while at the same time develop techniques for use in future models. I did add a lot of "beef" to the front ends, used a 4.5 ounce tank and re-did the control systems with stronger (usually heavier) components. That probably added 2-3 oz. of weight, even without the take-apart features. I'm also looking at ways to save weight there in future models, while still having stronger, smooth operating and accessible controls.

I really like the ARFs. They are light weight, well made, cost less and save lots of time. There is a rumor that Brodak is working on  ARFs of the Vector 40 and Strega.  If  that happens I think we eventually see them in F2B competition. I'm not the only one doing them with some removeable features. The Nobler, especially, lends itself to a take-apart wing. However, the vast majority are being nailed together as one-piece airplanes to get airborne quickly, which is in synch with the "ARF Philosophy". I may do a 5th Nobler and make it one-piece, just to have one in the low 40 oz. range where most of them end up. However, I must admit I'm getting a little tired of looking at sapphire blue Monokote!

Regards, Ed  Prohaska  This was written in September 2005

This is a second email received in

I can't promise any additional text at this time, as I'm swamped with other issues. Some of the methods I used are not new. In many ways it's similar to an R/C plane with bolt-on wings. Many years ago there was a magazine article on Paul Walker's Impact with a take-apart wing and tail. I have plans by Tom Dixon for a Vector 40 with a bolt-on wing and other such designs have been published.

Attached Photos of 4th ARF Nobler. 

I've done 4 or these, #1 and #4 for myself and #2 and #3 for other club members. All differ in some ways, but have many features in common. For all four models I:

+ replaced the leadouts with Sig .027" dia cable; ends wrapped and epoxied (almost everyone does this).
 
+ bushed the leadouts with brass tubes at the bellcrank in all but Nobler #1, which uses a Sig 4" crank cut to about 3 inches.

+ replaced the bellcrank nut & bolt with a pivot pin, except in #4 where the gum nut is replaced with a blind nut.

+ replaced the aluminum bellcrank with a nylon one, except in #4, where I'm using the stock bellcrank.

+ did not use the kit hinges; substituting Sig, Brodak, Goldberg or DuBro instead (kit hinges are useable).

+ replaced the stock flap horn with a taller horn (#s 2 and 3 use a stock horn at the elevator).

+ undercut motor mounts in the tank area about 3/16" and shimmed the engine down 1/8" for tank height adjustability.

+ removed the front former and added cross grain balsa between the mounts in the tank area and plywood up front as needed.

+ provided for a removable nose weight. It's usually not needed, but the option is there, just in case.

+ used a Brodak Medium Wedge 4.5 oz. tank, BH-483 or 490 (if ordered now, vent locations on #483 may have changed).

+ plumbed the fuel tubing so the uniflow line is easily accessed for filling and either ram-air or muffler pressure.

+ made a stronger 1/16" MW tail gear for stooge launching, with the axle bend in a "gravity biased" direction.

+ use a Sullivan Gold clevis only at the elevator horn, except #4 may fly with a clevis at both ends of the long pushrod.

+ attached the canopy with small screws through reinforced hard points, instead of tape or glue.

+ made the wing take-apart with maple blocks and threaded inserts in the rear and a reinforced anchor at the leading edge.

+ installed guides in the belly pan for the rear wing mount bolts.

+ always repainted the cowl with Sapphire blue Lustrekote

+ made sure everything inside is fuel proof, anywhere fuel could likely go (surprisingly, it doesn't go very far beyond the engine compartment).

+ used Bob Smith or Devcon 30 minute epoxy for most construction.

If you do an article, you are certainly free to use anything I send. Here are a few notes to go with the pictures. All are from Nobler #4:

01) I want to try the aluminum bellcrank, but without the stock clips and leadouts. The blind nut lets me loosen it to remove the pushrod and move it to a different hole or try a new rod. Once the belly pan is glued on I can't get to a gum nut to loosen the bellcrank anchor bolt. The large metric bolt and plywood floor seem strong enough.

02, 03) All 4 Noblers have guides for the rear wing bolts made from aluminum or fiberglass tubes. They are time consuming to install, but make it easier to deal with the bolts. It also looks "cleaner' from the outside.

04) The flap horn is a 4" Brodak BH-753 (three holes in the upright, 3/32" wire). I added spring bearings and brass retainers. The retainers are "pegged" with very short lengths of toothpicks that are trapped by the plywood plate on the bottom and the maple wing mount blocks on the top. To remove the horn, I remove the wing to expose the pegs, then pull them out with a #11 X-Acto blade. Horn holes in the flaps have been soaked with heated epoxy and lined with aluminum tubes.

On the first Nobler (most of the shop photos have been lost) the flap horn has no retainers. Instead I used 4 extra large Sig nylon hinges (1/4 scale hinges) on each flap. They are more than strong enough to support all of the aerodynamic and mechanical loads.

05) The pushrod is 3/32" music wire. The first 3 Noblers used a "L" bend in the pushrods at the flap horn and wood bumper on the inboard side of the fuselage to retain the rod. I'm trying a Z-bend with no bumper this time. A large radius bend in the rod lets me slip it in and out of the relatively snug hole in the horn. The upright has no brass bushings, but if it wears I can always replace the horn.

06) On Nobler #4 I took extra effort to conceal the hinges and tighten the hinge gap, while still getting 50 degrees of smooth up & down travel. This is a shot of the elevator hinge line. The hinges are recessed and the pin wire rides in a groove that's covered with Monokote. I don't know if there is any advantage to this. I just wanted to see how far I could go with hiding the hinges and closing the gap. None of the elevator horns have retainers. Loads are carried by a double hinge on each elevator near the horn.

07, 08, 09, 10) The 1st & 3rd Noblers are set up exclusively for the rear exhaust Stalker .40 BB. The 4th Nobler will use a Stalker, but with the option of switching to a FP or LA .35 through .46. To do that I mounted the engines on 1/8" steel pads (vs. the usual ply pad). I made one set of pads for the Stalker and one for the OS engines. Of course I have to setup 2 cowls, one for side and one for rear exhaust. For Nobler #4 I shortened the Stalker's muffler one inch, so I would not have to move the engine forward or re-work the stock landing gear mount and extend the cowl, as was done on #1 and #3. If the engine does not like the shorter muffler, I'll just use an OS in this one.

11) On Noblers #1, #3 and #4 I added lots of plywood to the front end to "beef" the motor mounts. The stock mounts are not hard maple and may be smaller than the usual 3/8" X 1/2". One mount is often misaligned. Sanding in a flat and level area to seat the engine removes wood. In most cases the mounts would not support a counter-bore for a blind nut, so I mount the nuts on a plywood plate that's epoxied on top of the mounts. All this takes a lot of time and work. It makes fitting the cowl more difficult, especially with pads under the engine bearers that lower it 1/8 inch. Eventually I get everything to fit OK and the finished front end looks about the same as a stock front end, except that it's much stronger and I can move the tank up nearly 1/4 inch, relative to the bottom of the motor mount lugs. That seems to be necessary with the Stalker, but not so much with a FP or LA where only about 1/16 to 1/8 inch of up-shimming is needed. With the more commonly used 2 inch wide tank, relative tank heights might be different. However a 2 inch wide tank won't fit in the ARF Nobler.

12) This is a typical 4.5 oz. Brodak tank used on the ARF Noblers. Some have all vents forward. This one with the overflow vent on the bottom, is easier to use. All require bending of any forward facing tubes to clear parts of the engine. If you have an engine that can run the pattern on 4 ounces, the shorter tank would be easier to deal with. The engine could be mounted a little further back.

13) I installed 1/16 inch music wire tail gear on all 4 Noblers, with the axle bent in a gravity friendly direction. Stooge flying is popular in the local club and the tail gear is the anchor of choice, so it must be strong. Noblers 1, 3 and 4 all have removable stabs. On #3 and 4 a "rudder plug" breaks away from the main fuselage for easy access to the stab mount bolts. This plug is held in by one 4-40 bolt on the bottom and a 1/8 inch dowel peg in the front. It's an interlocking set-up and very strong. It has to be because it holds the tail gear (aka, stooge anchor). The plug is not part of the stab anchor, but it does cover the stab bolts and they can't come loose with the plug in place.

Best Regards, Ed Prohaska



I loaded the photos in Nobler Take-Apart, Photo-Album section of Photo Gallery.  I have edited each one of the photos and added description text that explains or reiterates some of Ed comments in above emails.   Hope this helps and reduces some of the confusion.   

Hawk 
Email me at hoythawkins@aol.com or hoythawkins@bellsouth.net