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Building Tips and technical articles. => ARF'S => Topic started by: Larry Renger on April 12, 2007, 01:29:37 PM
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I am planning to start in on my Brodak Oriental ARF. It will have a Brodak 40 in it.
Tank type and size? Areas needing more structure? Control changes? Trim settings? Good prop to start with? What has been found out that needs changing or improvement?
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Larry: Beef up the landing gear attachent and make sure you have good wood to wood contact when attaching the wing. I know my wing came loose and I think Doc H. had a problem with his. The B-40 should be fine, I use a 10-5 in my Hawker Hurricane. I think I used the tank listed.
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Hi Larry...
Most B-40's like 4 1/2 ounces of fuel for the pattern.
I am also of the opinion that the instructions are wrong or vague about the control system...they work best with LESS flap movement than elevator...
Have fun!
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Larry, I would add that you should take along an APC 10 1/2 X 4 1/2 prop. It seems to work great around here on the Brodak 40.
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The Brodak 40 works fine for me on my Oriental ARF. I used the stock muffler and had to add about 1.5 oz. to the tail to get CG right. Part of the problem was due to the fibergalss cowl not fitting the fuselage well---caused me to mount the engine farther forward than I really wanted to. Later, I moved the engine back about 3/8 inch and built a small balsa cowl around the engine. Was able to remove about 1/2 oz. of tail weight.
I epoxied in a small piece of lite ply above the factory ply L.G. mount--made the L.G. plate about 1/4 thick--never had any gear problems.
I used a Brodak 4 oz. all tubes forward uni-flow trank--4.5 oz. is probably a good idea.
All that work didn't keep it from breaking up when I flew it into the ground, however---it is presently getting rebuilt for the second time. n~
Jim
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Larry,
Here are a few observations from my experience with my Oriental ARF.
1.) It builds nose heavy even with a light engine. Mount the engine as far aft as possible and then trim the back of the fiberglass cowl to fit. I think there is a note to this effect on the Brodak website.
2.) With the 1/1 flap to elevator ratio, mine would not turn very well. Set it up for the old 3/2 ratio and it turns much better.
3.) In switching from the kit to the ARF, Brodak changed the LG from wire to aluminum and in the process moved the wheels forward a bit. If I were going to build another, I would get the wire gear from Brodak and mount it on the aft firewall with "J" bolts.
4.) The covering around the nose comes off easily. As a minimum, when you fuel proof the tank compartment and bottom hatch area, let the epoxy lap over the covering a little. Again, if I were going to assemble another, I would strip off the fuselage covering and paint the fuselage black.
5.) Unlike some ARFs, this one has lots of tank space and good access, so might as well go with the 4.5 oz tank.
6.) I assume you will replace the hinges, pushrods, and clevises.
Steve
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Surely you mean 3/2 Elevator to Flap? More Elevator motion than flap motion? The other way around probably would go up and down without rotating at all.
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Larry,
I have mine set up for somewhat more elevator than flap movment--maybe close to the 2/3 flap to elevator ratio.
Jim
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Surely you mean 3/2 Elevator to Flap? More Elevator motion than flap motion? The other way around probably would go up and down without rotating at all.
Larry,
You are right, I meant 3/2 elevator to flap.
Steve
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Larry, you probably don't remember my Oriental at VSC. It is the one I had to almost completely rebuild. Stripped the covering down to bare wood. Reinforced the landing gear mount and also moved the metal gear as far back as I could. Cut top off fuselage so I could get good epoxy joint between wing and fuse. I also replaced the pushrods that came with the ARF. One of the clevises broke when I tried to put it on the horn. Also had to bush the horns as the holes were too big. I too have more elevator movement than flap. Best prop for me so far is Top Flite Power Point 11-4 on Sig 10% fuel and 4.75 ounces of fuel. Let us know how yours comes out. DOC Holliday
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Doc,
what engine are you running in your Oriental? 4.75 oz of fuel,, hmmm
I have one coming this week, thinking of an FP 40 or maybe my LA 46,, did you have to build a tank or did a stocker fit?
How did you come out on balance.
Thanks,,,,,
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Mark,
I'm not Doc, but I thought I would add my experience to your data base since not everyone has the same perspective. When I assembled my Oriental ARF, I had a new Magnum 36 that really wanted an application so it went into the Oriental. I knew that putting the 8 oz engine (about the same as an FP40) would cause the airplane to be a little nose heavy so I built in 1 oz. lead in the aft fuselage. When I got it together and checked the CG, it needed another ounce to balance. This was with a wood prop, very light spinner, and light tongue muffler. My tank is a 4.5 oz uniflow that fit with no effort. The long nose takes care of tank room and the tank compartment hatch makes access easy.
Unlike Doc, I did not move the landing gear aft and have had problems landing the airplane on paved circles. My Smoothie ARF with the gear located aft of the aft firewall lands pretty well, so location is probably a contributor to the problem.
Steve
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Doc,
what engine are you running in your Oriental? 4.75 oz of fuel,, hmmm
I have one coming this week, thinking of an FP 40 or maybe my LA 46,, did you have to build a tank or did a stocker fit?
How did you come out on balance.
Thanks,,,,,
Mark, I am running a Brodak 40 with tongue muffler. If you go with an FP or LA they are heavier. Even with the Brodak I have 1 ounce of lead on the tail. DOC Holliday
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Thanks gents, that is the kind of help I was looking for. Did you use the fiberglass cowling? I am thinking of making a balsa cowl in a more conventional manner, extend the top block and build a lower cowl. I am not real fond of the glass cowl the way it is set up.
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Alrighty then, work has commenced on my ARC Oriental. Upon reading the instruction manual,(yueah some of us do occasionaly) I saw no reference to a starting CG location. Any help here? I suppose I can surmise a good point, but I hate to add a couple oz of lead in the tail until I know a good starting location for the CG. If I missed the reference in the plans book please educate me,, I do sometimes miss stuff when reading,, especially when all eager to get er' done
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Brodak put an announcement on the web site to cover missing this info on the instructions. CG should be 1-7/8" back from the LE. I'm not sure this is the "final" location you will want, but it is a good starting point.
Steve
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Mark,
Ditching the fiberglass cowl is a great idea.
I just bolted my Brodak 40 in place (with backplate screws about 1/8 inch from the firewall), put a 2 inch spinner on the engine with a 1/16 inch spacer aft of the spinner backplate with a spot glued a 2 inch diameter lite ply nose ring aft of the spacer. Then I used epoxy to attach fuse side extensions directly to the engine mount beams and filled in with scrap 1/4 and 1/2 inch sheet. I didn't make a removable section but left an opening just big enough to remove the engine.
I have used this approach on two Oriental ARF's and also built a nose on my Score the same way---I like it much better than the fiberglass cowls.
Jim
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Jim: I'd like to see the cowls you made for the Oriental and the Score, Pics Please.
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Mark,
Ditching the fiberglass cowl is a great idea.
I just bolted my Brodak 40 in place (with backplate screws about 1/8 inch from the firewall), put a 2 inch spinner on the engine with a 1/16 inch spacer aft of the spinner backplate with a spot glued a 2 inch diameter lite ply nose ring aft of the spacer. Then I used epoxy to attach fuse side extensions directly to the engine mount beams and filled in with scrap 1/4 and 1/2 inch sheet. I didn't make a removable section but left an opening just big enough to remove the engine.
I have used this approach on two Oriental ARF's and also built a nose on my Score the same way---I like it much better than the fiberglass cowls.
Jim
Hi Jim,
Sounds like the original set up that Dee used on the Oriental. No cowl, just an open nose to remove the engine. Extending the fuselage sides in the "profile view" to give the illusion of a cowl.
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Well I can show you what I did with mine. FWIW, seemed to work fairly smoothly and I like it lots better than the glass cowl look. Note I also created a hatch for access to the rear elevator control horn. cut an opening, lined it with 1/64 ply for strenght and made a tab on the back of the hatch cover. I plan to hold it in place with a really complicated latch method,, ok so Im gonna use hinge line sealing tape.,, All I have left is to install the tank, I am going to use a uniflow vented Dubro 4 oz tank that reportadly holds 4.5 oz. add the tongue muffler and the wheels, then go fly. I built an ounce of lead into the tail. there is the solid balsa "cap" that fairs the horizantal area into the rudder. I hollowed that enough to bury my lead in it. initially it appears that it will be very close to balance. I do have a nice little tailwheel thats pretty heavy should I need it. Just put it on the scale with all the other stuff, looks to be right around 40.5 oz,, hmm still need tip weight so probably about 42 with tip weight and the tongue muffler.. hope she flies good.
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Ok Mark, you said you would SHOW what you did with yours. (hint,hint)
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Oh hey, DOH!,,
guess I should post the picts huh,, sigh, sorry I was in a hurry, Stepdaughter was playing division playoffs for Softball, I was headed out the door.. so here you go now,,,,
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Mark,
I thought I explained the "trick", tool-less, tapeless hatch to you. ;D
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Thanks Mark, I will use that cowl set up on future projects.
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Randy, yes you did, but um,, ah heck, its so darn skinny back in that area that truthfully, the 1/64 tab that locates this hatch is close to interference, This just seemed less problimatic seeing that the fuse was already in one peice, and I really couldnt come up with a clean way to gain room back there. At least I have some adjustment now,, and the tape really doesnt show much,, no really I mean it, sigh lol. Ok besides that, covering your cool hatch with shrink wrap is an intimidating thought...
Trust me, your cool hatch is one Idea that is catologed away for theft,, I um mean, use,, This is after all a desperate attempt to get two airplanes flyable before Eugene next weekend. skimping on cool trick stuff is ok, spending time on alignment and stuff that makes it fly better, well thats where I am focusing,, (I hope??? :-\)
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Unless you expect to do a large amount of elevator adjustment, why not just Moneykote over the hole? It worked fine on my Noblarf. I only had to re-do it once in the trim process, and that took less time than a hatch would have. Practicing what I preach (for a change) I am doing the same on my Smootharf.
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Actually Larry thats a pretty good idea, that thought hadnt even crossed my mind! I will keep that one in the bag of tricks too. and actually when she is trimmed in that may be the way to finish the deal.
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Leester,
Here are some pix of the Oriental (not quite finished) and the Score. I shortened the nose of the Score to help the "Droop nose" look abd used a 2.5 in. spinner
Jim
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Sorry to use so many posts!!
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Mark,
I was just kidding you. Looks great. Ted used a piece of Fascal over his hatch to hold it in place on the TP Special Edition. If it's good enugh for Ted....
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Thanks for the pics Jim, more ideas I can borrow.