I am passionate about building and flying scratch built foam park jets and passing on my experiences and lessons learned from more than five years of experience. Blog is purely based on my own opinions and experiences. If you have questions, please e-mail me at scott.parkjet@gmail.com. Park Jet noise...the "other" sound of freedom :) Happy flying! Cheers, Scott
Now that you have your GCRC F-22 Mini V3 ready to go, please remember to follow the recommended CG and throws per the documentation that is available with the plans. We went through a lot of testing and discussion over these to try and ensure folks had as much success as possible on their maiden flight, so please start with those. After you get your F-22 Mini V3 flying, if you want to adjust the throws and your balance point, be my guest, but we are quite confident that if you follow our recommendations you will have the best chance of success.😃
As it states in the features and specs document that comes with your plans, the recommended starting throws are 18 mm one way in the elevator (pitch) portion of the elevon and 30 mm one way in the aileron (roll) portion of the elevon.
Simply hold a ruler on the edge at the back of the elevon like so to adjust your starting throws correctly.
As for expo, I won't tell you what to set for that, whatever you feel comfortable with, but you might want to add 10% over what you normally use until you get the feel for how agile this plane is.
I shot this video awhile back about how I do my maiden flights, just food for thought, since you are probably not a beginner flying this plane, use what works for you😉
With the recommended power setup, I find about 40-45% throttle is sufficient to get the plane flying. I found this plane a bit of a handful to fly in any wind over 5 mph, so if possible, do your maiden flight with less than about 5 mph of wind.
The GCRC F-22 Mini V3 accelerates and changes direction very quickly even with the recommended throws, so give yourself lots of altitude and airspace on the first few flights until you get used to it's response to power and control inputs.
Best of luck on your maiden flight and I wish you many hours of enjoyment with this very fast, aerobatic park jet😎
Now that the bulk of the "fussy" work has been done, it is time to get this little beauty put together😊
I like to start with the fuselage so that the glue can be setting up and curing while I work on the rest of the plane.
If you are interested in what glues and tapes I use for building my park jets, please watch this video.
First, I like to put some clear packing tape down the center/bottom of the fuselage. This is not absolutely necessary, but will help prevent pulling the paper off the foam during numerous battery installations and removals over the life of the plane.
Then I install the velcro to secure the battery, in this picture I used three 2" lengths and started at the back where the score lines are to curve the back end of the fuselage inwards. This is sufficient for anywhere from a 1000-1300 Mah 3S battery.
To fold up the fuselage, you will make what is called a "B fold" where the side plates are beside the bottom plate as hopefully you can see in this picture. It is important to dry fit this before gluing so that you ensure everything will fit together nicely.
This is one of the few areas in the build where I find using hot glue works the easiest. I simply run a bead along the side of the bottom plate, then fold the sides in as shown above and ensure they dry at 90 degrees to each other. Do one side at a time.
Ensure to bend in the sides at the rear of the fuselage so that they are flush with the bottom and I find it easiest to "roll" the nose along the table to ensure the paper from the middle piece bonds to the side pieces. This picture was taken after my plane was completed, but hopefully you get the picture, I found it easier to form the bend in the foam by pressing/rolling it along the table til the glue took hold.😊
Once you are happy with how the sides of the fuselage have set up, glue on the top nose piece, using the slots in the side of the fuselage and the tabs on the nose piece for alignment. Take your time curving the foam and once you are happy with the dry fit, glue in place. I find it a good idea to use some masking tape to hold things in place while the glue dries.
You can install the battery hatch door at this point or wait until later. I simply hinge mine using a piece of transparent duct tape like I use for my elevon hinges.
While the glue is setting up on the fuselage, I will hinge my elevons using transparent duct tape. If you want to see how I do this, please watch this video.
To ensure I have everything centered and aligned, I like to make a small mark in the very center of the back of the wing plate on top so I can align my elevons.
I then tape the top of the hinge, ensuring everything is lined up correctly. I ensure to cut away any tape that covers slots where other parts will be placed. Also, I cut away some of the tape on either side of the mark you can see where my control horn will go. This way, no tape interferes with the glue joint later on. At this point, if you are planning on painting the plane, I would lightly scuff the surface of the tape with sand paper until it no longer shines. Otherwise, if you paint on the shiny surface, the paint can easily crack and peel off.
After the hinges are done on the top, I like to add a little "insurance" to the bottom of the elevon hinges as shown in the pictures below. Again, this is not required, but gives me a little extra piece of mind. I also demonstrate how to do this in the video above. This may cause your elevons to deflect up due to a bit of tension on the tape, but don't worry, the servo will be able to handle this and I would always rather have my elevons want to deflect up than down😉
Next, I install my control horns. I use the same control horns as Flite Test, but you can use whatever you have. Simply ensure the holes in the control horn are directly over the hinge line on both sides and your control horns are the same height, otherwise you can run into issues with your elevons deflecting unevenly.
I start by lining up the control horn, pressing down into the foam to mark the location.
Then using my knife, I carefully remove a small channel of foam where the control horn will go.
Control horn now lined up and in place. I secure these using five minute epoxy, I put a small amount of epoxy in the groove, place the control horn in and then if need be add a little bit more epoxy along the sides of the control horn to ensure they are securely attached and then let them dry fully before handling the plane.
Once the wing plate and fuselage are ready for handling, it is a simple job to slide the fuselage onto the wing plate, ensuring the fuselage lines up with the slot in the wing plate. The wing plate should be flush with the inside of the fuselage on both sides as you can hopefully see in this picture of one side.
I pinned the top fuselage into place while the glue dries to ensure it lines up well with the bottom since the motor mount will be going into this "square" area shaped by the top and bottom parts of the fuselage.
Leave these two pieces to dry completely before handling. In the meantime, you can get your motor mounted on the motor mount using bolts that come with the motor. Please note that the Racerstar BR2406S 2600 kv motor has an older 16x19 mm bolt pattern, so there is only one way it will mount to ensure the wires come out the top of the motor mount and fit through the groove you cut in the motor mount.
It doesn't really matter if you have the prop on or off at this point, if you feel safer, wait until later to install the prop after all the other electronics are installed. It does make it much easier to ensure the motor is aligned vertically and horizontally if you mount it to the wooden motor mount before gluing into the plane. I would recommend waiting til after you have installed your KFs and sanded them before mounting the motor, that way you won't get any sanding dust in the motor during that process.
After the fuselage and wing plate are securely glued together, it is time to mount the landing skids and the nacelles.
Make sure that the landing skids are oriented so that the two slots for the tabs from the nacelles are in the front. Ensure that the landing skids are perpendicular to the wing plate so that nothing gets crooked when you install the nacelle. You can glue the nacelle in place before the glue is dry on the landing skids, just ensure you square everything up and if necessary pin in place while the glue cures.
Next, install the KFs, either KF2 (just on the top) or KF4 (top and bottom). My personal recommendation is to go with KF4 as this is a very fast and agile park jet, so KF4 will give the best stability at speed and best wind penetration. It is also very important to remove the paper from both sides of both your KF airfoils. I shot this video about how I do KF4 airfoils on my park jets, I would recommend you watch it, starting at about 25:55 of the video. The first 25 minutes of the video discusses how I size KF airfoils for planes without them, but all that homework has been done for you with the GCRC F-22 Mini V3😃
As mentioned in the video, a couple of critical things is to ensure you mark the CG on the top/bottom or both of the KF airfoils before gluing them to the plane so that you still know where the CG is after marking it on the wing plate. You probably have already marked the top KF as the CG is marked on that part on the plans. Secondly, it is critical to ensure the trailing edges of your KF4 airfoils are even. Don't worry if the front on the leading edge of the wing is off, you are going to trim and shape that later as I demonstrate in the video. If you have your trailing edges off by even a mm or two, it will cause uneven lift on one or even both wings and your plane will become a bit of a handful to fly😨
I like to leave the KF airfoils to dry overnight so that trimming and sanding the leading edge the next day is much easier. The finished product should look something like this after shaping and sanding.
Note that I also tapered the edge of the top KF/wing plate of the "intake" area. I use 150 grit sandpaper and just a gentle touch. Paperless DTF can be soft and it is very easy to gouge it if you sand too hard.
Next, I installed the motor mount support pieces of foam that go behind the motor mount. I trimmed mine down a little bit to make it easier to fit them in as my fingers are a bit "sausage like"😉
Once those are dry and secure, I install my motor mount, using again 5 minute epoxy. This gives you some time to get it aligned by looking down the back plate behind the prop slot to ensure vertical alignment and then the line you marked on the bottom for horizontal alignment. I know these aren't the best pictures to demonstrate that, but hopefully you know what I mean.😊
Once the motor was dry, you can install your servos, run your servo wires, I use hot glue to install my servos as it makes it easier to remove them if they need to be replaced. Please note that the servo glues flush to the wing plate and is recessed down into the top KF. If your servo does not fit flush to the wing plate, you may need to trim a bit off your KF in this area to make that happen, always important to dry fit first. Do not install your pushrods yet as they will get in the way when setting the angle on your vertical stabilizers.
This is also a good time to place your receiver and ESC in the plane. I would do this before installing the vertical stabs as it is much easier to handle the plane without worrying about banging those into something. I like to place my ESC on the right hand side, since the prop will be spinning clockwise when looking from the rear of the plane, this extra weight on the right helps a bit with torque roll. If you choose to use a pusher prop and it spins the opposite direction, you might consider swapping the ESC and receiver positions, but it isn't overly critical unless you find torque roll is an issue.😊 Note that I placed both components back as far as they will go against the piece of bamboo skewer that is used to secure the hatch. You can install this piece of skewer before or after you install the ESC and receiver. I mount these components using velcro anyway, so it is easy to move them a little bit if need be and they can be removed if they are causing you troubles.
A small rubber band helps to secure the hatch in position for flying.
Next, install the vertical stabilizers, using the angle guide from the plans to ensure you get the correct angle on both sides. If your vertical stabilizers are not equally angled, it could cause stability and tracking issues. Pin into place if necessary to ensure the vertical stabilizer is angled correctly until the glue dries. Note that I cut the corner off the jig so that I didn't glue it to the plane where the glue seam runs between the stabilizer and the wing plate.
Once the vertical stabilizers are dry, it is a good idea to do any painting before installing the pushrods. I shot this video awhile ago about how I paint my planes.
On the prototype plane, I simply used some inexpensive magic markers I got from the dollar store with colors and a pattern that would make it easy for me to see in the air. This just takes a few minutes and adds no weight.😊
For my final plane, I did a simple "camo" pattern using diluted acrylic craft paints that I brushed on by hand.
Two important things to remember when painting your plane. Always test whatever paint you choose on some scrap foam to ensure it is not going to eat the foam. Normal "rattle can" paints from the hardware store are normally not good choices as the propellant can melt the foam. Secondly, also use as thin a coat as you can, the weight of the paint can add up quickly. My paint job on my final build added about 12 gr of weight to my plane. I just make the decals from paper, print them off on my printer and glue them on. I like to have a plane that looks good in the air and that I can see easily, not necessarily one that might win "best in show" sitting on the table at the field😉
Once the paint is dry, time to add your pushrods and ensure that the control surfaces are level. I like to do this with power on to the servos, so unless you have a kill switch on your transmitter to ensure your prop won't start up if you bump your throttle, remove the prop for safety.
I like to hold a ruler on it's side to ensure that my control surface is level with the wing plate. Ensure at this point you have no trim, sub trim or anything else that might effect the surface from being completely neutral.
So there you have it, one GCRC F-22 Mini V3 done and assembled. But, we are not quite done yet, in the next article, I will discuss throws, preparing for your maiden flight and some tips about flying this spirited little steed😎
Now that you have all your parts cut out and marked, it is time to get them ready for assembly. One of the first things to do is remove the paper from the wing plate where the KF airfoils will be attached. The easiest way to do this is to lay the KF on the wing plate, trace along the trailing edge and then use that line as your guide. I wrote this blog article that might be more helpful and detailed on how to remove the paper from DTF.😊
I also removed the paper from my electronics bay hatch door, this is optional, I just wanted to reduce the weight on my plane a little bit. Also, remove the paper from the small rectangular pieces that will attach behind the wooden motor mount and on the inside of all the nose pieces as indicated on the plans.
Once you have the paper removed where it needs to be removed, it is a good time to install the wing spar for reinforcement. I used two pieces of bamboo skewer, you could also use carbon rod/tube if you want to. I shot this video awhile ago that shows how I go about making the groove and installing my reinforcement in my park jets. As mentioned in the video, I find five minute epoxy works best for this as it dries relatively quickly and does not need exposure to the air to harden.
I used one long section (about 10" long) of bamboo skewer that would go across the opening for the electronics bay and then measured and cut a smaller section to fill the rest of the groove made in the foam. Hopefully you can see that in the first picture below. Note that I put waxed paper under the wing plate so that in the event any five minute epoxy oozes out, I don't glue my wing plate to the table😧
Once I have the reinforcement installed, I lay another piece of wax paper on top of the wing plate and then weight it down so that the reinforcement will dry flat in the wing. I know this looks like overkill, but you get the idea😉I will often leave this overnight as sometimes DTF can have a bit of a warp in it and this process helps to ensure the wing plate is as flat as I can make it.
While not critical, it certainly helps the plane be more efficient and faster if you taper the edges of the foam on several areas. It takes some time and patience, but is worth it. Either way, you will probably want to seal the edges of the foam to prevent the paper from peeling off if you are using Dollar Tree foam.
Although you can use hot glue for this, it will weigh your plane down, so it might be best to use tape along the leading edge of the nacelle to prevent paper from peeling off on landing and hope for the best on the rest of the plane😊 Otherwise the paper can get peeled off the leading edges of the nacelles and landing skids after a few landings. I also remove about 1/2" of the paper along the very back of the wing plate (on top only) where I am going to attach my hinges. I also do this on the top of the elevon so that the tape has a section of bare foam on which to adhere. Here are a series of pictures of areas where I have trimmed the paper from the foam.
Trailing edge of the wing top and bottom, about 5mm wide.
As already mentioned, about 1/2" along the very back of the top of the wing plate where I will be attaching my elevon hinge tape.
Leading and trailing edge of the prop slot.
Leading and trailing edge of the nacelles.
All around the edges top and bottom of the elevon, note the 1/2" edge area where the paper is removed for the hinge tape. I also do the same thing around the outer edge of the vertical stabilizer although I forgot to take a picture of that😳
I also remove the paper from the leading and trailing edges of the landing skids. In the picture below, you can see I have already sealed the edge of the paper as I describe in the blog post linked in the first paragraph of this article.
After all the edges of the paper has been sealed, I gently sand a taper on all the edges (except on the back of the wing plate and the elevons where they will be hinged) to ensure a nice smooth airflow over my plane. Also, do not taper the leading edge of the wing at this point, that will be done later once the KF airfoils have been attached. Once I have all the sanding done, I actually vacuum all the parts to get any remaining dust off them using this brush attachment on the vacuum. I find it is the easiest way to get the pieces clean😊
This next step is not necessary if you don't every think you will get your plane wet, but if you live in an area like I do where even in the summer you might get some moisture on your plane from the wet grass, I highly recommend you treat your plane with oil based Minwax polyurethane or other similar product. It is important to use an oil based product as water based will saturate the paper.
Otherwise, the paper will absorb the water, make the plane very heavy and eventually the paper will fall off which can compromise the strength of your plane. I wrote this detailed article on how I do the Minwax treatment. In that article, I included a Flite Test video on how they demonstrate applying the Minwax. As the video is unlisted, if you click on the words Flite Test video in the previous sentence, you will be taken there.
Although in the video they mention it best to Minwax after the plane is assembled, that is a bit more difficult with this plane, so I applied the Minwax before assembly, doing one side first, then the other after the first side was dry.
It is very important to stir the Minwax, I just use a popsicle stick to ensure you get all the resin off the bottom of the can, especially if it has been sitting for awhile. Otherwise, you won't be getting the full protective effects of the product. I use the inexpensive foam brushes I can get from the dollar store to apply and then paper towel to remove the excess Minwax before leaving it to dry completely.
While I am waiting for the Minwax to dry, I find it an excellent opportunity to set up my electronics and program my transmitter so that I know everything is good before I get busy with assembly.
I used the very inexpensive FlySky FS-i6 transmitter to fly my F-22 Mini V3, if you want more info on my journey evaluating this great little transmitter, please check out this playlist on my You Tube channel.
