Scratch Built Kwik Fli III
10-01-2017, 05:28 PM
#1
Thread Starter
Scratch Built Kwik Fli III
I wanted to build a "Classic Pattern" for a while now, but was unwilling to compromise on having it petrol powered. This has delayed this build until I had suitable engine on hand.
10cc Spark ignition was an option I considered at the time, however, the extra weight penalty was too high (additional ignition battery and ignition module).
When the OS GGT10 was introduced, this build became viable, and I ended up selecting the Kwik Fli III as a project, with plans downloaded from outerzone.
From the start, a decision was made to build the structure as close to "as designed" as possible. Wing will be constructed on a jig as stipulated in the plans.
One change to the original "structure" design will be the use of dual servos for ailerons (and therefore omitting the linkage system in the wing from the single servo). All gear used will be modern.
I hope you enjoy the photographic build posts.
Start of project - Cutting the plans to sections to fit the available space in the "Cave" (as my RC room is known).
Eran
10cc Spark ignition was an option I considered at the time, however, the extra weight penalty was too high (additional ignition battery and ignition module).
When the OS GGT10 was introduced, this build became viable, and I ended up selecting the Kwik Fli III as a project, with plans downloaded from outerzone.
From the start, a decision was made to build the structure as close to "as designed" as possible. Wing will be constructed on a jig as stipulated in the plans.
One change to the original "structure" design will be the use of dual servos for ailerons (and therefore omitting the linkage system in the wing from the single servo). All gear used will be modern.
I hope you enjoy the photographic build posts.
Start of project - Cutting the plans to sections to fit the available space in the "Cave" (as my RC room is known).
Eran
10-02-2017, 05:06 PM
#4
Thread Starter
My friend Brian was lucky enough to find this "A-justo-jig" wing jig on ebay a while ago, and kindly provided it for this build.
Also building RC aeroplanes since around 1987, I have never used a jig before.
Back to the build, some glue finally in use to make some of the wing parts, and ribs drilling in preparation for the jig commenced.
Eran
Also building RC aeroplanes since around 1987, I have never used a jig before.
Back to the build, some glue finally in use to make some of the wing parts, and ribs drilling in preparation for the jig commenced.
Eran
10-03-2017, 06:19 AM
#5
I scratch buit a Kwik Fli a year or so ago. It flies fantastic. I also built the wing on an adjusto jig. I replaced those two flimsy plastic "L" brackets that hold it with something heavier duty made out of plywood. I then mounted the whole jig to a torsion box so it would be straight.
I did the ailerons per the plans using two bellcranks and one central servo. Works very well and no problems. I'm not a fan of dual servos. Had problems with them in two different planes. Also I think bellcranks are lighter. Mine came out at 5.6 lbs ready to fly (dry). It was covered in fabric and Randolph dope and I put a K&B .61 hot-rodded by none other than Clarence Lee himself.
keep the pics coming
carl
I did the ailerons per the plans using two bellcranks and one central servo. Works very well and no problems. I'm not a fan of dual servos. Had problems with them in two different planes. Also I think bellcranks are lighter. Mine came out at 5.6 lbs ready to fly (dry). It was covered in fabric and Randolph dope and I put a K&B .61 hot-rodded by none other than Clarence Lee himself.
keep the pics coming
carl
10-03-2017, 10:53 AM
#6
I have wanted to build a classic pattern plane as well but have too many Scale projects on hand at the moment. The Kwik Fli III is one of my contenders along with the Kaos 60 and the Phantom I (V2). I like the fact the plans are easy to get and there are even laser cut kits available if you want to be lazy and not cut it out yourself.
10-03-2017, 10:42 PM
#7
Thread Starter
Thank you for the comments carlgrover and FlyerInOKC. I must admit that cutting parts is not my favorite part of scratch building, and I am happy to go for the "lazy approach" sometimes. As to the use of dual servos, I was using this method for all my aeroplanes in the past 15 years, so I will stick to it with this one. With the exception of the airframe build, this is not a trip down memory lane or trying to be authentic about the gear used, so I will stick also to modern covering using Monokote. Funny about the engine mentioned, I was offered a brand new (with new bearings and checked for rust) O.S 60 Gold Head for this build, which I kindly declined. I am not going back to glow fuel anytime soon.
Out of curiosity carlgrover, did you have the "tail wiggle" I am hearing about from few people who were flying the Kwik Fli III in the past?
The jig assembly went without an issue, I bolted it directly to the table. So far all is going mostly to plan...
Eran
Out of curiosity carlgrover, did you have the "tail wiggle" I am hearing about from few people who were flying the Kwik Fli III in the past?
The jig assembly went without an issue, I bolted it directly to the table. So far all is going mostly to plan...
Eran
10-05-2017, 10:50 PM
#11
Thread Starter
Thank you for the advice FlyerInOKC, this is what I did.
The "secondary spar" will not fit to the notch in the ribs as shown in the photos. It is way too wide in the centre section and this cause it to be out of the corresponding notch further outwards of the wing.
While thinking of a solution, I glued in the plywood "joiner" to the main spar. Then I decided to rectify the problem with the secondary spar by notching it to accommodate the ribs. This worked quite well. This wing will be super strong.
Eran
The "secondary spar" will not fit to the notch in the ribs as shown in the photos. It is way too wide in the centre section and this cause it to be out of the corresponding notch further outwards of the wing.
While thinking of a solution, I glued in the plywood "joiner" to the main spar. Then I decided to rectify the problem with the secondary spar by notching it to accommodate the ribs. This worked quite well. This wing will be super strong.
Eran
10-07-2017, 01:21 AM
#14
Thread Starter
Thank you Carl, I was wondering how pronounced the tail wiggle is.
FlyerInOKC - I can see your point with tapered wing. I wish the jig was much larger as most I usually build aeroplanes much larger then the Kwik Fli III.
Progress update. W1 centre rib is in place, as are the other "forward section only" W9 "ribs".
The "secondary spar" plywood joiner (DB2) and the leading edge were also glued into place.
Eran
FlyerInOKC - I can see your point with tapered wing. I wish the jig was much larger as most I usually build aeroplanes much larger then the Kwik Fli III.
Progress update. W1 centre rib is in place, as are the other "forward section only" W9 "ribs".
The "secondary spar" plywood joiner (DB2) and the leading edge were also glued into place.
Eran
10-10-2017, 09:42 PM
#17
Thread Starter
FlyerInOKC - Yes, I could not make the wing any better without the jig.
Some progress since the last post:
The landing gear plywood "ribs" mounts are now in place, as is the bracing in the centre section (which by design had the single aileron servo attached to them).
Next is sheeting the D-Box. Starting from the bottom side, I first soaked the balsa and strapped to the D-box to create the curve. Once mostly dry, the glue was applied. I used both Polyurethane and PVA glue.
Eran
Some progress since the last post:
The landing gear plywood "ribs" mounts are now in place, as is the bracing in the centre section (which by design had the single aileron servo attached to them).
Next is sheeting the D-Box. Starting from the bottom side, I first soaked the balsa and strapped to the D-box to create the curve. Once mostly dry, the glue was applied. I used both Polyurethane and PVA glue.
Eran
10-12-2017, 12:10 AM
#18
Thread Starter
More sheeting... This time over the TE.
Notice the bevel of the last centimeter of TE section where the top and bottom sheets will be glued to each other. It was easily done by having the sheet hanging from the edge of the table and using the sander in an angle.
Eran
Notice the bevel of the last centimeter of TE section where the top and bottom sheets will be glued to each other. It was easily done by having the sheet hanging from the edge of the table and using the sander in an angle.
Eran
10-14-2017, 12:44 AM
#19
Thread Starter
With the bottom sheeting in place, I marked the aileron gap and glued the "aileron sub ribs". These will be used later to cut the aileron free.
I also glued into place some lite play, which will be used to hold the horn screws. The width of the aileron at this cross section will not allow standard horn screws to pass through.
Eran
I also glued into place some lite play, which will be used to hold the horn screws. The width of the aileron at this cross section will not allow standard horn screws to pass through.
Eran
10-16-2017, 11:05 AM
#22
I don't remember but I swear I sheeted my wing while it was still in the jig. Maybe i'm wrong. What I do remember is that my adjusto jig made the straightest wing I've ever built. 1 click of aileron trim on the first flight is all it took to fly straight.
carl
carl
10-17-2017, 06:11 AM
#23
Thread Starter
Thank you FlyerInOKC.
carlgrover - The landing gear mounts had to be installed prior to sheeting and I could not glue them in place while the wing was on the jig. Also, sheeting the bottom first made working on the jig less practical. I also found out that working on the jig probably produced the straightest wing I have ever built...
More progress with the left aileron repeating the work already described for the right aileron. Wet balsa in place for top of wing sheeting.
Eran
carlgrover - The landing gear mounts had to be installed prior to sheeting and I could not glue them in place while the wing was on the jig. Also, sheeting the bottom first made working on the jig less practical. I also found out that working on the jig probably produced the straightest wing I have ever built...
More progress with the left aileron repeating the work already described for the right aileron. Wet balsa in place for top of wing sheeting.
Eran
10-17-2017, 06:58 AM
#25
Thread Starter
FlyerInOKC - I use the 3M blue tape. It is one of the most useful tools I have in my possession. I use it for so many things. Temporary labeling, temporary hold, masking (when painting) etc.
Funny how some cheap minor tools / items become the most used. For example, I don't know how I was able to work for many years without self closing curved tweezers...
Eran
Funny how some cheap minor tools / items become the most used. For example, I don't know how I was able to work for many years without self closing curved tweezers...
Eran