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Author Topic: Brodak F-8F Bearcat  (Read 344 times)

Offline Jim Carter

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Brodak F-8F Bearcat
« on: January 28, 2018, 02:10:19 PM »
Hello everyone!  I had some communication with Charles, Aviojet, regarding posting the build of my Brodak F-8F Bearcat and I decided to accept his offer.  I hope each of you enjoys the posts.  Oh, and just to let everyone know in advance, when I build, I've developed a habit (whether good or bad) of documenting each step I do similar to a daily diary. and I'll be posting pretty much just as I wrote each days work.  So, with Charles' permission, let's get started :)

Brodak Bearcat

A few months ago, I watched a YouTube video showing the history of the US Navyís Blue Angels and for some unknown reason, that video really tweaked my desire to build a model of a Bearcat.  Since Iím currently spending most of my flying time on control line it didnít take me long to research the available kits of this aircraft.  A few years ago, I built one of the Brodak Profile Bearcats for a fellow who was active in carrier flying so I knew the Brodak line would be a good product choice for selection.  Over the course of the next couple of weeks, I was able to entice some of the members of our little flying group, The North Brevard Figure 9ers, to join me and build one of these models so we could someday, field a full squadron of these planes.  Six of the guys bought into the idea and the idea came to life.

I ordered the kits plus the needed tanks and wheels and on Saturday, October 7, 2017 the kits were distributed and Sunday, October 29, 2017 I opened my Brodak BEARCAT to review the plans for a moment then I tried to see if I could find a set of retracts for it.  Iíll probably settle for a set of E-Flite .40 size electrics, if I can afford them.  I had the plans copied and scanned onto my flashdrive for future reference.
With all that done, I decided to begin assembly of the Brodak BEARCAT.  It really is quite a nice kit; the laser cutting is very good and the balsa is very nice.  I read through some of the instructions then began punching out some of the diecut parts and grouping them together.  Since I donít have one of the Brodak wing jigs, I decided to begin construction of the fuselage.  For the most part, I did my best to follow the instructions as spelled out in the very informative manual but honestly, I knew I was going to deviate somewhere before the thing is completed!  I started by laying each of the parts in the relative positions according to the plan before beginning to do any gluing.
 
As I was about to begin, I noticed that the fuel tank I had received was the wrong one; I received a BH-589 rather than the recommended BH-498.  Both are 4 ounce tnks but the 598 is taller and shorter than the recommended tank.  So, I placed an order for the correct one, as well as a request for the decals to be printed in yellow keeping in line with the photos of the real aircraft. 
    
I began the work of framing the fuselage.  With that essentially done, I a decided to deviate from the instructions and glue up the parts for the vertical stabilizer.  From there, I began framing the lower cowl at least according to the instructions and the photos provided.  They honestly didnít make any sense to me, even with the photographs but the problem most likely is mine, as I write this.  Frames A-C and B-C donít fit or either I put something together wrong.  According to the plan, it looks like itís one piece but the parts donít fit as smoothly as I would have suspected.  If it is truly one piece, the plan is poor in depicting how it should be assembled and there are no clarifying photos in the instruction book.  Anyway, I had to trim the frame B-C so that it would fit between the sides against the front of frame B.  Then using a piece of parchment paper I fitted and clamped frame D-C against frame D, then fitted the F-2 cowl floor between the frames B-C and D-C.  I used some Windex to soak and soften the ends of the fuselages sides so that they could be formed around the A-C frame.  Next, I fitted the frame A-C against the cowl ring and held it in place using a number of pins.  Finally, I added the 1/4" x 3/8Ē stringers to complete the basic framing and then give consideration to sheeting.
    
With that done I marked and began fitting the upper cowl block.  Next, I began the process of sheeting the lower cowl.  I used a mixture of ľ x 3/16 and 3/16Ē sq. balsa sticks to get the shape Iíll need.  Over the course of the afternoon, I was finally able to come up with a reasonable shaped and fitting of the lower cowl.  I used a piece of brass tube as the slot for inserting the 4-40 hold down bolt that gets screwed into the blind nut hold down block.
    
Once I was satisfied with the fit and seating of the lower cowl, I marked the location for the engine glow plug and then opened the cowl sufficiently to give a 3/16Ē clearance around the OS 40 FP cylinder head.  I also opened a couple of holes for the fuel tank fill and vent lines.  I applied a coat of Z-Poxy Finishing Resin to the engine and fuel tank compartments.  While the epoxy cured I decided to assemble the horizontal stab and elevator.  It was a fairly straight forward process with no particular issues.



Offline Jim Carter

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Re: Brodak F-8F Bearcat
« Reply #1 on: January 29, 2018, 08:25:16 AM »
This portion of the build documentation summarizes actions that occurred over the period of about a month and it began the shaping process of the horizontal stab assembly, the forward portion of the fuselage and the wing.  I followed the instructions using the appropriate sizes of brass tubing to rough sand the elevators halves and the horizontal stab as required.  I was very pleased with the final results and finished by rounding the leading and trailing edges as shown on the plan.  I opted to use the Brodak brass mounts, BH-745 for the elevator joiner and after marking all of the locations I made the necessary slots and used some Brodak EZ hinge, BH-927, rather than the Dubro hinges provided to mount the elevators.  The elevators were in place and the setup looked good.  I ran out of EZ hinge and will need to get some more before the surfaces can be permanently glued in place.

When I resumed work on the BEARCAT, I used one of the Dremel grinders to carefully grind the slot for the tail wheel strut then used thick CA to sandwich the wire in place as well as the maple anchor block.  Next it was a fairly simple matter to glue the mount in place under the stringer.  At this point Iím way out of sequence with the instructions, so I decided to begin planking the forward section of the fuselage.  Rather than trying to wet and shape balsa sheets, I opted to use some 3/32Ē x ľĒ sticks.  Personally, I think this is a bit easier but to each his own!

Once the planking was done, it was time to spend a few minutes shaping the upper cowl block.  With that done, I shaped and installed the landing gear blocks followed by shaping the wing leading edges and applying the leading edge sheeting.  Doing this without a jig was a bit of a tedious process but I believe I was able to avoid building in any significant warp.  Next, it was time to fabricate the bellcrank and leadout wires according to the instructions.  This is the first time Iíve ever built a model using the long mounting post and it will be interesting to see if there is any difference in performance especially since itís using a 4Ē bellcrank. 
    
During another session, I worked to fit and join the wing halves.  It was quite a task especially trying to keep from building any positive or negative incidence into the wing.  I added some scrap balsa to reinforce the joints inside the top and bottom sheeting and so far, it looks good.  I took a bit of a break to update the logs and transfer a few photos.  I completed the mounting and installation of the bellcrank assembly, the adjustable lead out guide along with the addition of the cap strips for the wing.  I used thick CA to glue the leading edge sheets in place then prepared to begin the initial shaping process.

Offline Avaiojet

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Re: Brodak F-8F Bearcat
« Reply #2 on: January 29, 2018, 07:09:18 PM »
Jim,

Great build! As always. H^^

I had a Brodak Bearcat kit but sold it. Can't remember who bought it?

I have the correct Blue Angles graphics.

So let me know when you need the graphics and I'll get them out to you. No charge.

Thanks for the Build.

Charles
Alpha Mike Foxtrot.

Owner of CFC Graphics. "Model Airplane Graphics from a Model Airplane Builder."

"No one has ever made a difference by being like everyone else."

Marcus Cordeiro, The "Mark of Excellence," you will not be forgotten.

I look at the Forum as a place to contribute and make friends, some view it as a Realm where they could be King.

"Ya gotta love it when a plane comes together."

Proverb 11.9  "With his mouth the Godless destroys his neighbor..."

"Perhaps the greatest challenge in modeling is to build a competitive control line stunter that looks like a real airplane." David McCellan, 1980.

Offline Jim Carter

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Re: Brodak F-8F Bearcat
« Reply #3 on: January 30, 2018, 09:34:08 AM »
Jim,

Great build! As always. H^^

I had a Brodak Bearcat kit but sold it. Can't remember who bought it?

I have the correct Blue Angles graphics.

So let me know when you need the graphics and I'll get them out to you. No charge.

Thanks for the Build.

Charles
Thanks in advance.  I'll be breaking the build in segments, daily and each segment will cover about two or three weeks worth of actual time, if that's alright.  As it goes forward through the research segment, you'll see the color of the graphics I'll be hoping to acquire.  I have the ones that came with the kit and I can send them to you so the size and font will be similar, should anyone else need them.

Offline Perry Rose

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Re: Brodak F-8F Bearcat
« Reply #4 on: February 07, 2018, 02:35:01 PM »
I built one a few years ago. It's not an easy build but it is a great flying plane. .46 LA, all blue color.
I wouldn't take her to a dog fight even if she had a chance to win.

Offline Jim Carter

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Re: Brodak F-8F Bearcat
« Reply #5 on: February 08, 2018, 07:35:00 AM »
I built one a few years ago. It's not an easy build but it is a great flying plane. .46 LA, all blue color.
Thanks Perry.  You're right, it is a bit of a challenging build but I and another of my flying buddies went over the top (so to speak) and modified a few things with no idea whether it was a good idea!  ::)  %^@

Offline Jim Carter

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Re: Brodak F-8F Bearcat
« Reply #6 on: February 08, 2018, 07:59:01 AM »
After shaping the leading edge, I decided to do a test fit of the wing and fuselage and it looks pretty good.  I resumed work on the BEARCAT and worked to shape the wing tips.  I left the outboard tip solid whereas the inboard tip has to be hollowed out to allow for the adjustable leadouts.  During my next session in the workshop, I began by hollowing out the inboard wing tip for the BEARCAT and by 1030 or so I had a pretty nice wing tip shaped and ready for mounting.  Iím not sure but I may have the slot a bit too wide but Iíll deal with that when itís time to cover the wing.  I mounted the inboard wing tip.
 
Iím torn as to whether to make the wing removable so I began working on the flap assembly.  I read a portion of the instructions, then marked the hinge locations and center lines for the flaps, then temporarily mounted the control horn to see how it seated.  Now, it was time to begin shaping the flaps.  I followed the recommendations to use the three different sizes of music wire and although it took a bit of time using 80 grit down to 250 grit sandpaper, the finished product came out acceptable.  Next, came the fitting and aligning of the flaps using E-Z hinge.  I chose these rather than the Dubro hinges because of the likelihood of misaligning one of them and ending up with a binding or twisting of the control surface.  Besides, I think they are easier to install, pin and replace if necessary, at this point of construction.
    
I added the top and bottom center sheeting and with that done, I tack glued the wing to the fuselage and began the slow process of aligning the horizontal stab assembly level and aligned with the wing.  At that point, I was able to install the two sections of the elevator pushrod.  The instructions call for soldering the joints but I opted to use two 5/32Ē Dubro wheel collars.  I applied a good coat of Thread Locker to secure them to the pushrods joint then checked the alignment of the wing to the horizontal stab alignment.  I went over all of the essential areas of alignment again and made any needed adjustments until I was satisfied.  At that point, I applied thin CA to all of the hinges and glued the wing in place to the fuselage, adding necessary shim and filler as needed.

Offline Jim Carter

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Re: Brodak F-8F Bearcat
« Reply #7 on: February 08, 2018, 08:30:52 AM »
I opted to reset the OS 40 to get a feel for the fit of the lower cowl and begin the shaping process.  After that, I mixed up a small amount of JB Weld and applied it to the joints and point of overlap of the elevator pushrod connection.  I certainly shouldnít have any problem with it coming loose due to vibration.  Next, I completed the lower sheeting for the wing then applied the sheeting to the aft portion of the fuselage.
    
During the next session, I focused on completing the bottom aft sheeting along with adding the tail block and the braces to protect the pushrod from excessive flexing and vibration.  I set to work applying the turtle deck sheeting for the BEARCAT and when it was done I test fitted the vertical stabilizer. When I was satisfied I attached the vertical stab and rudder assembly then competed a fair amount of shaping and sanding in preparation for finishing.  I spent a few minutes going over some various ideas for mounting the fuel tank and the fill and overflow lines.

On Saturday, December 23, 2017, my flying buddy came by for a visit and we spent a few minutes kicking around the idea of tearing into the Bearcatís wing to install some retracts.  We decided that it was doable but itís going to be quite a job!  After he left, I placed an order with Tower Hobbies for the Insignia Blue Monokote and a Dubro muffler extension for the OS 40 FP engine.  I spent the next couple of hours pondering the best way to configure the fuel line fill port on the BEARCAT.  I decided on using a Dubro Filling System, Dub-840 that I had on hand. 

During this session, I was able to shape the nose, mount the fuel tank and get it satisfactorily seated into the fuselage.  Then, I turned my efforts to  making a second attachment bolt for the removable lower cowl before applying a coat of finishing resin to the inside of the engine and fuel tank compartment.

Offline Jim Carter

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Re: Brodak F-8F Bearcat
« Reply #8 on: February 12, 2018, 10:42:05 AM »
I received my order for the muffler extension and the roll of insignia blue monokote and began the session by mounting the muffler extension, Dub-699, to the BEARCAT.  It looks pretty good.  I also test mounted the removable cowl and it worked just fine.
 
Well, it was time to commit to the installation of the retracts.  For this I opted to use the E-Flite 15-25 size electric retracts.  I used the fixed strut from the kit to figure out the length of the retractable strut where the axle and wheel should be mounted.  Then I placed the retract unit over the fixed block so that the pivot point was in the same position as the fixed strut thus allowing me to estimate and mark just how much of the 1/16" balsa sheeting would need to be removed from the wing for a 2-1/2" wheel to fit.  With sufficient sheeting removed, I estimated the depth of the axle and wheel assembly so I could remove the appropriate amount of rib R-2.
    
Because the fixed strut was shorter than the retract unit, I decided on making the retract beam mounts long enough to extend past the R-4 rib.  This meant cutting four hardwood (4) beams 4-1/2Ē long and mounting the retracts about 61 mm from one end of the beam.  The width of the beam mounted retract assembly was 35 mm so I carefully removed the fixed gear mount and then cut the beam mount seating slot approximately 25 mm from the edge of the wing sheeting into ribs R-3, R-4 and R-5.  Also, I fabricated a 1/16" plywood doubler for each of the R-5 ribs to strengthen them.  I really felt silly because normally, I make templates of all kit parts for future repairs and or replication but this time, for some unknown reason, I didnít do it thus it was a bit of a pain making a decent doubler. 
    
With them cut and fitted, the doublers were superglued to the R-5 ribs then test fitted the beam mounted landing gear.  This was a slow and tedious process because I had to make sure the gear unit was recessed enough so that the unit is below the wing sheeting and yet the gear doors would be flush with the wing sheeting.  Also, the angle of the gear would place at least half of the wheel forward of the wing leading edge to avoid nose overs upon landing.
    
Also, to be on the safe side, I added a length of plastic tubing to act as a shroud and guide protecting the control line that will be running through the inboard wheel well.  Once I was satisfied with the interim placement of the retract units, I began the process of mounting them into the wing and reinforcing the joints.  This definitely was a challenging modification but it was completed and functioning by the end of the session.  Next, I fabricated some spar webbing to go between the ribs R-2 to R-5.  I fabricated the wing cover sheeting to enclose the retract assemblies, fitted and glued the covers in place and then shaped them allowing sufficient clearance for the wheels in the wheel wells and the addition of the gear doors.  With that done, I made an access hatch in the bottom of the outboard wing for the battery and receiver.
    
I added some reinforcement to the R-2 and R-3 ribs in case there is some bouncing or movement of the battery.  I certainly wouldnít want the battery breaking through one of the ribs on a bounced landing.  Next came the installation of the radio gear.  To this end, I used a small dab of medium CA to hold the retract connectors in place against the wing skin.  I applied a bit of 5-minute epoxy onto the underside of the top wing sheeting between R-3 and R-4 to strengthen the inside compartment that will be holding the battery and between R-1 and R-2 since I opted to use a small piece of Velcro to hold the receiver in place.  As for the switch, it was mounted on the actual hatch and fitted on the inboard side of R-3 thus keeping it out of the battery compartment which is between the ribs R-3 and R-4.
    
I successfully tested and cycled the system a few times and was satisfied that the basic installation was sound.  Only actual flight testing will shake out any problems that need to be corrected.  I fabricated the liners for the BEARCAT wheel wells.  With 2-1/2Ē wheels I knew I would have to make the wheel wells at least ľĒ larger in diameter to afford a nice fit but then again if there is any bending of the gear due to a bump or rough landing it could prevent the smooth operation of the retracts.  I used 1/64Ē ply to line the cutouts for the wheels using two pieces of 1/64Ē x 2Ē x 4Ē with about ľĒ overlap to make a 7-1/2Ē long piece.  Then I had to fit, adjust, trim and re-trim such that the liner allowed the free operation of the wheel.  Once satisfied, it was tack glued in place using thin CA then trimmed flush with the surface of the wing sheeting.
    
When both retracts were operating satisfactorily, I took a few moments to make a brief video or them cycling up and down.  The setup looks good.  Now to mount the landing gear doors.  This required a bit of creativity because the axle required the use of a piece of scrap balsa as a spacer between the door and the axle also the mounting holes had to be relocated from the kit positions.  I opted to use a couple of sets of 2-56 bolt and nut sets to clamp the gear doors to the axles.  The tricky and patient part came when trying to ensure the gear doors seated properly.  Because the retracts are a significant modification to the wing it will be almost impossible to completely enclose the wheel well without a near complete redesign of the wing and Iím not willing to do that since this is not a ďtrue scaleĒ model.

Offline Avaiojet

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Re: Brodak F-8F Bearcat
« Reply #9 on: February 13, 2018, 08:03:28 AM »
Jim,

Looking really good!

Robart wheels. What size are they?

Charles
Alpha Mike Foxtrot.

Owner of CFC Graphics. "Model Airplane Graphics from a Model Airplane Builder."

"No one has ever made a difference by being like everyone else."

Marcus Cordeiro, The "Mark of Excellence," you will not be forgotten.

I look at the Forum as a place to contribute and make friends, some view it as a Realm where they could be King.

"Ya gotta love it when a plane comes together."

Proverb 11.9  "With his mouth the Godless destroys his neighbor..."

"Perhaps the greatest challenge in modeling is to build a competitive control line stunter that looks like a real airplane." David McCellan, 1980.

Online Glenn (Gravitywell) Reach

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Re: Brodak F-8F Bearcat
« Reply #10 on: February 13, 2018, 12:42:02 PM »
Hi Jim, just wanted to say how much I am enjoying your build.  You have raised the bar on how a build should be done.  Almost too much information to take in and the build tips are super!  Thank you so much for taking the time. H^^
Glenn Reach
Westlock, Alberta
gravitywell2011 @ gmail . com

Offline Jim Carter

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Re: Brodak F-8F Bearcat
« Reply #11 on: February 14, 2018, 06:53:35 AM »
 :)  Thanks Charles!  Thanks Glenn!  As for the wheels, I ordered the Robart 2-1/2" but as I'll be mentioning a bit later in the build, I had to replace them with 2-1/4" wheels.

Glenn, I appreciate your words.  I struggle with just how much info to add especially if I'm doing something different from the plan or published instructions.  Yet I recognize that any one who would seek to follow a similar path would also have the skills and knowledge to do their own thing.  I just hope the process and end result is acceptable to fellow model builders  :)


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