critterhunter

Thought I'd post this in it's own thread. Although most of the mods and inspiration has been learned on the Way Past The Limits thread, I figured it'd be easier to post the pictures and mods on a seperate thread so newbies can be pointed to it. I've heard many complain that they don't want to wade through the hundreds of posts to get to the details and so here it is. Not that it deserves it's own thread but just for the reasons above.

Although I've condensed down proven mods and methods to build a Stryker from scratch into one thread, I would still encourage you to read all the Dark Side "Way Past The Limits" F27 threads from start to finish. It makes for very interesting reading to see the initial impressions of this plane and how ideas evolved and became extinct over time. For every twenty or so "good ideas" that came and went only a few survived to be time tested and proven. For this reason I ask that you feel free to respond to this thread but only with a modification that has proven it's self with use and time. Any theories, ideas, or notions should be kept on the Way Past The Limits thread where they can prove their worth first. As a side note, when tracking down those threads I believe they are listed as Part 2 through 4 but the initial thread is called something different. Just look for "F27" in the title and a ton of messages and you'll know you found the proper thread.

The Stryker is a pretty strong and hardy plane right out of the box. However, with a few simple mods it can be made much stronger to address a few weak points. Some of these mods are also for ease of use in the field, eliminating things like tape or hinges that can take more time and be a pain to work with between flights. For what it's worth, after flying numerous stock and brushless Strykers, finding numerous good ideas on the dark side threads, along with a few ideas of my own, these mods are the best I've found for me while keeping the skills required as low tech as possible so I can do them.

My latest rendition of a brushless Stryker build was just completed last night and I took numerous pictures to help walk the newbies through the process. You'll be surprised at just how much punishment this plane can take with just a few simple precautions and modifications. Hope it helps...

Before we get started with the carbon tubes I'd just like to quickly point out that carbon tubes are hollow and carbon rods are solid. The stock carbon rods in the body are just that...rods. The round carbon tubes we will be installing are just that....tubes. I some times mix up the words so keep that in mind.

The first two pictures here are of installing carbon tubes into the nose to tail and wing tip to wing tip areas. These are essential for a brushless Stryker to prevent body or wing flex at high speeds. While a stock plane doesn't really need them as much and can probably get by with just the Extreme strapping tape (Office Max or Staples), they will greatly help to prevent crash damage as well.

The two carbon tubes I'm using are .210" OD x .132" ID x 40". These are about the perfect size for the plane. At one time I had used carbon arrow shafts but these were way overkill and also made for cutting it close when melting the wing foam channel. Whenever I have to remove foam from a body I like to melt it out. I feel it retains more strength than cutting. For the carbon tube channels I use a larger soldering iron to first melt them out.

First, trace out the wing tip to wing tip carbon rod on the body. You can simply install the rod straight and have it just meet the two stock body rods, ending there. However, bending the rod as shown in the picture will get it to the very wing tips and help strengthen them even more. It helps to have an extra set of hands while doing this, one guy bending the rod in place while the other traces it out.
Notice that the rod is right up against the vertical fin humps. If you place it here it should clear the stock motor mount screws and even the new 27C mounts but, just in case, I'd place the motor mount on the foam to confirm there is no conflict with the screws.

Next, go ahead and trace out the nose to tail carbon tube channel. I like to extend the tube to the very front of the body where the nose mounts. This will help prevent the body in this area being distorted on a hard nose in crash. The wing tip to wing tip tube will sit under the nose to tail tube as there is more foam in the body from nose to tail to have that tube sit higher while still remaining flush with the body.

Next step is to melt out the wing tube channel using a large soldering iron or something else to get the job done. Test the heat of it first on some junk foam to make sure it isn't too hot and result in melting too much foam away. Once you've melted out the channel test fit the tube. You want the channel almost deep enough to sit the tube flush with the surface of the plane. When it's close I like to use some sandpaper or a drimel to sand out the last little bit. This gives you more control to prevent going too deep and also smooths the foam for good contact with the tube.

After that's done melt out the nose to tail channel and sand it. Test fit the tubes into their channels with the nose to tail tube crossing over the wing tube. All should be flush with at least nothing protruding out of the foam. Using weights and perhaps clamps sit the tubes in place. Don't worry about cutting them to length yet because it aids in holding them where they need to be. Now pour or brush your favorite glue over the tubes and in the channels. I prefer Epoxy but something like Weldbond (craft stores) also works well. I don't try to save weight by going light on the glue...filling any gaps between the tubes and foam as I go.

Once all that is done you'll now have a pretty strong body to prevent flexing in flight or crash damage. The two tubes crossing under the motor mount will really help prevent any foam damage there in a bad crash. As anybody who's flown a stock Stryker knows, the motor mount loves to chunk off the body foam under it in a bad crash.

Last picture is of a screw being removed from the nose cone. You'll find it hidden in a hole in there and it helps to use some needle nose pliers or such to remove it. This item was being placed in the nose to correct a tail heavy condition early Strykers had. Don't worry, you won't need it and it's just extra uneeded weight.

critterhunter

Next photo is of the canopy/battery hatch glued together to form one unit. This will greatly ease use in the field. Heat up a knife and melt off the latch as it won't last very long at all. While your at it throw away the latch catcher that goes onto the body...uneeded weight. If you have newer 27C hatches there will be some dimples on them that are supposed to help hold it to the body. Melt them off as well. Next, glue the two together at the lip and use some flat carbon stock to strengthen the joining even more. The lip alone will not be strong enough in a bad crash.

We are going to use magnets to hold the canopy/battery hatch to the body and the nose on as well. Tape is a pain to work with and I've tried rubberbands, velcro, prayer, and various other methods in the past but by far magnets are the best. It makes for quick and easy service in the field. It also helps to prevent chunking foam because there is no physical connection between the parts and the body. So, if they need to fly off in a crash they won't take foam with them. Why not just glue the nose to the body? Because the nose needs to come off in a crash to help absorb momentum and slow the plane down. I'm using magnets to magnets for the contacts but on a stock slower bird you can probably use magnets in the body and just thin metal on the part to hold them together. Use magnets in the body it's self. That way if you loose a part you've only lost a piece of metal and not the magnet. Just remember, if using magnets on both sides like I am you need to check the poles before gluing them in. One side of the magnet will repel the other magnet while the other side will attract.

Next photo is of some magnets and 1/4" dowl rod to hold the nose/hatch to the body. I'm not sure if these magnets are rare earth magnets (lightest with strongest hold) but they are darn strong. Found them at a Pat Cattans craft store.

Third photo is of the melted holes on the front of the body to hold the nose to the plane. Use some pliers to heat up a screw and melt two holes. Test how hot it is on some junk foam before melting them out or it might melt too much. Make them a bit deeper than the dowl rods/magnets need. Now put a good bit of epoxy into the two holes and then stick the dowl rods in them...sticking out just a bit for now. Now put some more epoxy onto the head of the dowl rod and stick the magnet onto that, pushing down until the magnet is flush with the foam surface. Pushing the dowl rod further in with the magnet will insure that the two are making good contact when the magnet sits flush with the foam. It's good to use more epoxy than needed in the hole so some will flow up and out of the hole when you push the magnet/rod flush. Spread this extra epoxy over the entire front body surface where the nose sits. Do the same with the nose's side when you install the dowl rod/magnets into the nose. It will help strengthen the foam in these areas to prevent chunking.

critterhunter

Next photo is of tape stuck on the nose that has been circled with a marker. Here's how and why...Take some tape (the tape that was on the nose from the factory will work) and after the nose magnets on the body have dried stick it on them. If using regular tape make sure the sticky side is up. Now install the nose onto the plane and press hard then remove it. The tape should now be on the nose where the nose magnets need to be to match up to the body magnets. Circle the tape with a pen or marker and then remove the tape. Go ahead and melt out the dowl/magnet holes on the nose for them. Again, make the holes a bit deeper than need be and fill them up good with epoxy. The dowl rod, by the way, helps to hold the magnet in place. If just using a magnet and no dowl rod you can probably get by with filling the hole with epoxy alone but you risk the magnet pulling out.

Next photo is of the magnets glued into the nose and, again, spread the excess epoxy over the entire nose mounting surface to strengthen it.

Next photo is of the canopy/battery hatch magnets glued flush with the body surface. If you place them exactly where I have them the front of the canopy will sit flush with the foam but the back of the battery hatch (where the latch used to be) will be slightly elevated with the magnets glued to the battery hatch. If using thin metal it won't be an issue but I prefer the battery hatch being raised a hair anyway for added venting. If you want it flush but are using magnets on the hatch as well instead of metal you'll need to sink the body magnets a bit rather than being flush. I wouldn't worry about it because the "grey" (used to be grey...black on the 27C hatches) back cover goes under the battery hatch anyway and will make the gap far less noticable.

Once the body magnets have dried put some tape on them and press the canopy/battery hatch down hard onto the body. Lift it up and you should have tape stuck to it where the magnets need to go to mate exactly with the body magnets. Remember to check polarity of the magnets so they attract instead of repel each other!

critterhunter

Next photo is of the magnets glued to the canopy/battery hatch.

Next photo is of some spray adhesive to aid your tape being put on the body. Do NOT spray this stuff directly onto the body or it will melt it. And, only lightly spray it on the tape before installing it on the plane. If there are globs or heavy spots on the tape wipe them off first...or let the stuff start to dry or it will melt the foam causing bumps on it. You don't need the spray to help the tape stick but I prefer it for an even better bond. At least wipe the body down with some tacky cloth (found in auto parts stores...used to get dust and oil off the body before bondo or painting) to remove any finger oils or dust.

Next photo is of the 27C ailerons (they are black) attached to the body. These look like the 27B ailerons and come with the hinges as well but they are said to be stronger. I've used the 27B ailerons and hinges on my previous builds using a BP21 brushless motor with no problems so these should hold up to the new 2409-12T motor speeds. Some prefer balsa ailerons and I've used them in the past with Dubro Heavy duty hinges. However, the balsa won't flex as much in a crash and thus you risk chunking the body foam where the hinges are mounted. Others have also installed balsa on the trailing edge of the wing to counter this. However, it's more work than needed in my opinion. These stock flaps already have the hinges on them with the perfect placement to match the body hinge depressions and the right gap so there's no hassle to installing them. Look at it this way, if the stock flaps get bent or chewed up over time it will only take about $3 and a few minutes to install new ones. Simply unhitch the hinges and throw on an new pair. Well worth the time and hassle saved over trying to play with custom jobs.

Spray some glue onto some Extreme strapping tape and fold it from top to bottom over the trailing edge of the wing. Take a knife and poke holes in the tape/foam where the plastic hinge holders should go before trying to press them in or you risk breaking them when trying to push them in. The Extreme tape will prevent the hinges being pulled through the foam and also strengthen the trailing edge of the wing a bit more for less flex. Has worked great for me in the past and much easier than messing with balsa or glassing.

critterhunter

Next three photos involve modding the stock motor mount so that a BP21, 12T or other bell type outrunners will mount to it easily. Many people have made custom mounts or modded the stock mounts in various ways but this blend of mods I developed make it about as easy as it gets. No motor thrust angle worries or complicated custom builds. It will work with either the old motor mount or the new 27C ones. If using the old style mount also put some epoxy onto both sides of the "stand" between the rings and the platform (it looks like a "V" channel) as they like to break right there. You'll see the three parts I use in the first photo...Some PVC tubing, a plastic bottle cap (or aluminum works well too), and a Megatech spinner cone.

First install the PVC tubing into the motor mount hole to measure and cut it to the desired length. This will strengthen the rings on the old mount and help the new style mount as well. Next, grind off the sides of the bottle cap or grind down some thin aluminum to the proper disc size so that it will just fit inside the back of the motor mount flush with the screw holes. Glue the disc into place and then glue the PVC tube into the mount as well. Then assemble the two parts of the Megatech spinner cone with glue and glue it onto the end of the PVC tube. This will greatly enhance both the looks and the wind flow of the mount.

Next photo is of the mount glued together.

The next picture is a bit blurry but you can see I used an aluminum disc instead of a bottle cap. A plastic bottle cap makes things a bit easier because you can just heat up a needle or thin nail and melt out the motor's metal plate holes. You'll have to drill them out using aluminum. Take the metal mounting plate off your motor and center it onto the back of the motor mount. Dab some paint or something (white-out works well) into the three holes so you know where to drill them out on the motor mount. Some people drill the metal motor's mounting plate to match the four holes on the 27C motor mount but I'd rather just drill out three new holes to match the motor's. You'll also need to drill out a hole dead center in the bottle cap/disc so the motor's shaft will clear it when mounted flush. You might not need to do this but might as well just in case. I prefer to mount the motor's metal plate in such a way that the set screw for it is at the top. It makes removing the motor later easier.

I'm using button head sheet metal screws (I think the size is #4 x 1/2") to mount the motor's metal mounting plate to the motor mount. Go with the smallest sheet metal screws you feel comfortable with and as short as possible to save weight. The main concern here is that the head is big enough to not pull through the hole on the motor's metal mounting plate, yet not so big that it hits the raised ring on the plate and won't sit flush. Make sure you use the proper size drill bit or don't melt/drill the holes too big. You may have to drill out the three holes on the motor's metal mounting plate a bit to make the screws fit. The screws don't need to thread or screw into the motor's metal plate and can be loose in it. The plate will snug to the motor mount when they are screwed into the disc you've created. That's where to pay attention to hole size. If you don't feel the screws are snug enough when screwed in you might dab a bit of epoxy or something on them. If you still have concerns then I'd also put some glue onto the back of the motor's metal mounting plate. It's better to have a hard time removing the plate later on then have the motor come loose in flight and rip it's three motor wires out.

critterhunter

Next step (and photo) is of melting out the battery chamber. You'll notice a raised foam platform in the front of it. If using a lipo you'll want to melt that down flush and also melt the whole chamber down a little lower so the lipo sits lower and clears the hatch. A 2000 or 2200ma 3 cell lipo sitting snug against the back of the battery chamber should balance the plane perfect as they weigh about the same as a 7 or 8 cell nimh pack. If you are using a nimh or something different you might wait to melt this out at the end when you decide where the battery needs to sit to get center of gravity perfect. I'm using just some bent aluminum held with pliers and heated with a propane torch to melt the chamber out. Remember to test it on junk foam to insure things aren't too hot and may melt more than wanted.

Next photo is of melting out the ESC chamber. You can wait until you've placed the motor/mount onto the body for a test fit and have it soldered to the ESC (Don't lengthen the motor or ESC wires....they are long enough) so you can figure out the exact spot you need to melt to fit the ESC in properly. Since I'm going for airflow I just melted it all out in that area. Make sure you don't melt out too wide an area that the back cover won't cover and hide. You'll also notice a small thin melted out channel at the very end of the plane. That's where the three motor wires will route through under the motor mount and into the ESC chamber. They'll need to stack one on top of another to fit this thin channel but it's better than a wide one that might show up at the tail end of the back cover. Some people drill out the 27C motor mount to route the wires through the plastic. I prefer not to do this because drilling will weaken things. You could also just route the wires along the side of the motor mount but the way I did it above makes for a much cleaner and hidden look.

Next photo is the top vertical fins being cut down by the width of a ruler. This makes the plane look much better, lessons flex of fins, and will increase turning and roll ability without a loss of glide stability. Just remember to lower your rates on your radio because she'll be much more sensitive!

critterhunter

Next photo is just of completed and painted motor mount. I used Fussion paint (Walmart) because it's said to stick to plastic better. Works good on foam to. As for painting the body you can use just about any paint on the market because this foam won't melt. I like the cheaper Walmart Color Place paint for this but used Fussion paint this time.

Next photo is of foam sprayed into the front empty chamber. This is called "Great Stuff" and comes in a can from Home Depot and such. They sell two types. I like the one that expands more. You can also use it to spray in any unused battery chamber. It will expand and then expand some more so you'll have to keep an eye on it for about thirty minutes or so and spoon off any excess. You don't want it getting too high and blocking airflow from the canopy. If it grows on you and dries before you get to it don't worry because it will cut fairly easy with an exacto knife. When spraying it in keep the tube at the bottom of the chamber so you're sure it is filling all the gaps and gets a nice thick flow in there as well. Afterwards clean out the tube and the top of the can or you won't be able to use it later on as it will plug up. Spraying it into the front chamber will really help prevent the "nose up" syndrome a Stryker can develope after a few hard nose crashes. The carbon tube from nose to tail helps alot but the more the better.

Next photo is of routing the antenna. The RX usually likes to site in the very front of the chamber behind the battery chamber up against the wall where the latch catcher normaly goes. You'll notice the antenna channel under the wing doesn't go all the way to this chamber. Simply poke a hole straight down through the chamber with a hot nail or such and then route the wire outside the body. Then melt a channel for it to meet the stock antenna channel.

critterhunter

Next picture is of the RX sitting where it should and you can also see the holes for the servo wires poked through from the bottom of the plane where the channels end and up into the RX chamber.

Second photo is of the sheet metal screws package and the motor plate screwed to the motor mount.

Next is of the drilled out hole so the motor shaft doesn't bump the disc.

critterhunter

Next photo is of the motor shaft being cut down to a much shorter length. Make sure you place your bullet prop adaptor next to it to measure where you need to cut. I prefer this (Maxx, I believe) type of prop adaptor that has a set screw to secure it to the motor shaft. Others that don't feature this have come loose on me. Grind a flat spot on the side of the motor shaft for the screw to sit against and prevent slipping. The prop end of the adaptor is threaded and the prop is secured by screwing the bullet head down. Stick something in the bullet head's hole to really torque it tight. Don't forget the proper size plastic ring that should have come with your prop to secure the prop on the adaptor shaft. By the way, the BP21 and 12T have a 3mm size shaft so you know when shopping for prop adaptors.

Next photo is of bullet motor wire plugs soldered to the three motor wires. They, along with some Deans Ultra battery plugs, are only $4 more when buying the 2409-12T motor and 30 amp ESC combo deal from Aero-Nuts. Well worth the price and greatly eases swapping motors/ESCs in the future. Don't forget to install some heat shrink tubing before soldering things up. I prefer to hold the bullet plug in a alligator clip vise and then use a mini torch to heat up the plug while I flow solder into it's hole. Then just heat it back up and stick the motor wire right in there...holding it still until it cools solid. Much easier than working with a soldering iron.

Next photo is of the ESC to battery plug wires soldered to the ESC. Use a male Deans Ultra for the ESC's wire leads side and a female on the battery's leads. This helps prevent the battery from shorting should you use a male on it which has exposed pin ends. Don't do it! Use 14 gauge or larger wire on the ESC leads to lengthen them and use too long of wire for now so that when you set the motor/ESC on the body for a test fit to get an idea of the proper length you can cut off the ESC battery wires to where they are just long enough to reach the battery plug and then solder the male to the ESC leads. I prefer the battery to sit with it's wire leads at the front of the chamber, then wrapping them up over the battery to the ESC battery plug. That way I can secure the battery wires under the velcro along with the battery. More later on that.

critterhunter

First photo in this next post is of the three motor wires bullet plugs installed. Remember to swap two of the wires connections so the motor runs backwards (prop size numbers on an APC prop should face the FRONT of the plane in a pusher configuration like this!). Notice I used some fuel tubing along with the heat shrink tubing to protect the plugs. That way you just unplug them from inside the fuel tubing and there is no worry of shorts in flight.

Next photo is of the control rods I'm using and clevisis. The stock control rods like to break at the little dimple that goes into the aileron control horn. Don't trust them at brushless speeds. I'm using 2-56 size fully threaded (from end to end) control rods and steel threaded 2-56 clevisis. With fully threaded rod you just cut off the proper length and screw the clevisis on both ends. Much easier than soldering rods to a solder clevis and such. Hold the control rod and clevisis up to a stock control rod so you know exactly how much length you need. Always have a bit more rod then needed so there is room for adjusting trim on the clevis. While I'm on the topic, I prefer the clevis in the top hole on the servo horn and the bottom hole on the aileron horn. This gives maximum throws. Then simply adjust the rates on your computer radio to lower the throws to desired levels. I prefer a mild rate on lows and a fast but fun rate on highs. Many people switch to low rates when doing low fly bys or when landing/taking off. Don't forget some fuel tubing on the clevis to keep it snug against the horns. While on the subject of servos it might be a good time to point out that most brushless Stryker owners prefer Hitec HS81 servos or HS81MG (metal gears). I use the non metal gear ones and haven't had one strip yet. They are a perfect fit to the body servo holes and will take a lot of abuse. If you don't feel the servos are snug enough when you get to installing them in the body then you might dab some glue on them to hold them in place. I've never had to but be sure about it.

Next photo is of test fitting the motor/ESC to the body so I can measure and cut the ESC battery leads to proper length. Install the battery to measure when doing this. You at least need the Deans Ultra plug from the ESC battery leads to reach a bit into the battery chamber or it will be a real pain plugging it into the battery.

When soldering the deans ultra male and female connectors to the ESC and battery leads here's the easiest method I've found. While I have fairly good soldering skills the large surface area of the deans ultra plugs combined with the heavy gauge wire you are trying to solder them to can make things tough. Mainly, even with a large soldering iron it can be tricky to get both the wire and the plug pin's surface hot enough at the same time to flow solder over them correctly for a good joining. Your first step should be to lightly sand the deans plug surface where you plan to solder the wire to, then put some flux on the pin and the wire to aid in attracting solder to them. I use an alligator clip "helping hands" style holder (Harbor Tool & Freight or elsewhere) to hold the plug and the wire together in the way I want them to solder together. Next, I take a mini butane torch (Again, Harbor Tool for about $5 or elsewhere) to heat them both up quickly and stick the solder directly onto them as I do so to where it instantly flows over the two surfaces. If things get tough and the solder isn't sticking re-clean both surfaces with sandpaper and flux and try again. As with all other soldering, make sure you've slid some heat shrink tubing over the wire and well past the heat source until the soldering is done. Once the solder cools give a pretty good tug on the connection to make sure it's good and then slide the heat shrink tubing up over the connection and use a heat gun (hair dryer or lighter if nothing else) to shrink the tubing over the connection to protect it. After that's done you can solder up the other lead in the same steps above. When soldering the female deans ultra plug to the battery ALWAYS only expose one battery lead at a time and solder and heat shrink it before proceding with uncovering the other battery wire and soldering it up as well. If both leads are exposed or you haven't heat shrinked the first one while trying to solder up the other you ARE asking for problems. if the two wires short in some fashion get away from the battery quick and watch it from a distance to be sure it isn't going to explode or catch fire. For this reason I'd also do all my battery plug soldering outside in a safe area that isn't going to catch something on fire. Also remember to check and double check the polarity of your connections before soldering the ESC or battery plugs to their wires.

critterhunter

Next step and photo is to test the servos movement to make sure they are orientated properly before installing. Match them up to the bottom holes and be sure about this! You don't want to test them installed or they may be moving the wrong way and rip out some foam. Have the radio and plane on and make sure your trims, sub trims, etc are all set at neutral. Unscrew the horn from the servo and place it so the horn is slightly forward from being straight up and down. Stock birds came this way and for whatever reason most people like the servo horn resting at neutral slightly forward (towards the nose) a hair.

Next photo is of the servos with rods installed in plane.

Next is of the RX being glued in with weights.

critterhunter

Next photo is of the velcro being glued in to loop around and hold the battery in place. You need to do this regardless of how you have the hatch secured to the body or it WILL come out when pulling hard Gs! Some like to cut holes in the body and loop the velcro around the nose to tail carbon tube but I've had good luck just using epoxy. Install the battery and snip off any extra length of velcro not needed. As an added precaution some people attach a short length of bright streamer to the battery. That way if it does somehow exit the plane when stunting it will be much easier to see it fall to the ground or find where it landed.

Next photo is of how I like the battery to sit with it's battery wires routed under the velcro as well. I believe at high speeds unsecured wires could have enough momentum to push off the hatch when pulling hard Gs.

Next is of clear tape being used to hold the servos in. Don't forget the spray adhesive on your tape as you tape things. Run it all the way to the nose to tail carbon tube so it's end will hide under the Extreme tape that will go over it. Angle it so it passes completely over the servo but just misses the finger holders on the bottom of the plane. The other end of the tape should go an inch or two past the servo. Also, somewhere along the lines in this thread you'll notice that I poked holes at the end of the servo wire channels right next to the rod so they can route up into the RX chamber. In this photo you'll also see the antenna wire and stock carbon rod has also been taped over using a single piece of clear tape as well. End this at the nose to tail tube as well. Clear tape over the other stock body rod as well. When taping the antenna in place it helps to put a dab of some kind of sticky glue on the wire so you can seat it down in it's channel when taping over it. Having a loose antenna try to move around on you while trying to tape over it is a real pain. If your antenna wire is long enough to hang off the end of the wing you might consider routing it back onto the body somewhere in front of the aileron (melt a channel) and taping over it. However, there are some who think this may shorten the RX range so be aware.

critterhunter

Another photo of the clear tape over the antenna/rod.

Next photo is clear tape over servo/stock rod.

Last is of Extreme tape over wing tube and (I think the nose to tail tube already). Extreme tape will aid the carbon tubes in strengthening the body even more for less flex.

critterhunter

Next photo is of Extreme tape over the motor mount area on the top side. Wrap it over and under the bottom side as well, then put tape from left to right on the top and bottom to finish it off.

Next is of the bottom side taped up.

Next is of clear tape on the entire leading edge of both wings. This really helps prevent foam being chunked or cut into on landings when hitting objects. Again, don't forget some spray adhesive for a better grab. You may have to use 2 or 3 seperate pieces of clear tape in order to be able to flex them around the body contours where they curve at the wing tips and as the wing gets closer to the nose in order to avoid wrinkles. Tape it to the very wing tips but not over the Extreme strapping tape on the ailerons and such. I try not to cross tape over tape to make it easier to remove a single piece for a repair or to get at something should need be. The only exception to this is the servo/stock rods tape that I like to end under the single piece of Extreme tape that covers the nose to tail tube. Also, at the motor mount I prefer two or three layers of Extreme tape to help prevent the motor mount from chunking foam and prevent flex with motor torque.

critterhunter

Next step is to cut the tape where the motor wire channel is.

Ready for paint! I put some blue painters tape on the top of the flaps because I wanted them to stay black. Again, wipe down the body with some tack cloth for a better grab of the paint if you feel like it.

Side view. Since the RX is already in place (has to be since you have to tape the antenna down before painting...tape doesn't stick to paint well), try not to paint it's servo pins or they may not make good contact with the ESC or whatever else you are plugging in. The servos should already be plugged into the proper ports.

critterhunter

While the paint is drying on the top of the plane let's make a better heat sink for the ESC. You'll notice one side of your ESC is perfectly flat and smooth. This is where a metal plate is to help bleed off heat. It's always good to use an ESC that is rated to handle about double the amps your motor/prop is going to draw. In such a case you probably don't need to add a heat sink so long as you have good airflow over it. Since my 12T motor is probably going to draw close to 30 amps with the prop and lipo I'm using I'll be pushing my 30 amp speed control to the limits. You can push them some times even higher than the amps they are rated for providing you cool them properly. I have good air flow but I want to make sure it stays cool by adding an extra heat sink. I used a heat sink that goes on a brushed can motor to cool it. Just cut off a piece and flattened it, then sanding off the blue paint. Take an exacto knife and cut off some of the heat SHRINK ("Shrink", not "Sink"!) from the heat sink side of the ESC to expose it to the one you plan to add. I went up to Radio Shack and picked up some heat sink paste to help the two heat sinks to conduct to each other better. I gobbed it in the middle of the new heat sink and then put some epoxy at all four corners to hold it onto the stock heat sink since the paste doesn't glue them together. If you can't find a good heat sink Radio shack sells some. Try for aluminum or copper to save weight and/or for better heat conducting properties.

Next photo is of the ESC being glued into place after you've installed the motor mount onto the body. Use a nail or something to poke through the tape/foam on the body where the motor mount screw holes go. It will make inserting the screws through the body easier. Even with the tape under the motor mount the stock screws will be long enough. Just remember the longer ones go at the front and the shorter at the back.

Next is of the ESC throttle wire being secured with a garbage bag metal twisty tie. Dab some glue on the tie and secure it to the bottom of the chamber. You don't want the wire flopping around in there. Cut off any excess tie length to save weight.

critterhunter

Next step is to glue the back cover onto the plane. It's front end should just reach the edge of the magnets. Put on the front hatch/canopy to make sure it's sitting where it all should. The double sided tape on the back cover will NOT hold it on at brushless speeds! Remove all the tape before gluing...extra unneeded weight. Might be a good time to check servo/motor functions one last time before gluing it on.

Next photo is of the completed and painted bird. Not too bad. A little tape wrinkle on the leading edge. Go easy and light with the paint or the tape may lift/wrinkle a little.

Last photo in this message is of the black painted underside of the plane. I prefer a light color on top and a darker on the bottom because the plane will always have a shadow underneath it in the sky anyway and the dark/light orientation of the body helps to quickly figure out which way the bird is sitting up there.

critterhunter

Only three more photos, I promise!

critterhunter

That's about all there is to it. Of course there are different mods, methods, and sequential steps others use to build this plane but this one works for me. Simple and direct without too much in the way of skills...that's me. It also helps to always think ahead in steps or you may get ahead of yourself (painting before taping, etc.), but if you follow the above in order you shouldn't run into that kind of problem. I make no promises or gurantees as to the quality of these mods in both safety and use. In other words, use at your own risk and as always fly in a remote area where an in air failure won't hurt people or property. NEVER fly over roads, cars, other people, houses, etc. Never land the plane at you or others. Keep in mind a brushless motor can push this plane well over 100 mph and those carbon rods could go through a person or piece of property like an arrow! Also, watch out for the prop when throwing the plane or you might loose a hand! In short, BE CAREFUL!

Hope this helps others build this great plane. It's parts are cheap and ready to find on most store shelves, not to mention it has great flying ability at super high or very slow speeds. It's a plane that can almost do it all. Enjoy!

critterhunter

After reviewing this monster size post there's just a few things to add to clean up the details...

First, even if you aren't adding an extra heat sink to the ESC always sit it in so that the flat smooth size of it (heat sink) is on top and exposed to air flow.

Remember to check the center of gravity once the plane is done and painted. On most newer Stryker bodies the sweet spot is right where the two circle holes are inside the finger holds. I prefer mine to be a tad bit nose heavy (about 1/4th an inch or so forward of the circles inside the finger holds) so that if I make repairs or something shifts the plane has some room for error and still not be tail heavy. A tail heavy plane will not fly well at all and will soon be out of control. Don't add weight but rather move the battery forward or backward to get COG proper. In most cases you'll find using the BP21 or 12T motor and a 3 cell lipo in the 2000 to 2200ma range the COG will be perfect. Mine was right at the circles on this build.

The vertical fins should not be glued in place. They should be snug but able to come off in a hard landing or you risk chunking foam. I find that after painting them and the body they are very snug. Newer fins have plastic tab holders but I have no experience with them and probably wouldn't use them to keep the weight down.

Last step should be to trim the ailerons out to be perfectly flat with the wing surface. Use the clevis on the flap horns to do this and make sure your radio and plane are ON so the servos center themselves. Make sure trim, sub trim, etc is all at neutral before doing so.

When I launch the plane I prefer the motor at full throttle or near that. When you throw it do so directly into any wind and make sure you keep moving forward with your arm and in a downward motion AFTER you let go of the plane. This will help prevent you from cutting off a finger or worse.

Once you've got the plane up to a high and safe height you can adjust your trims on the controller to get it flying straight and level. The next step is very important and involves checking motor thrust angles...

With the plane flying straight and level (helps to do this on a calm day or straight into any wind) at full throttle kill the motor. If the plane remains flying straight and level the motor thrust angle is probably correct. If the nose instantly rises up then you have too much downward motor thrust (the motor is too low in the back and was pushing the nose down when on). If the nose moves down when you kill the motor then you have too much upward motor thrust (the motor is too high in the back) and was pushing the nose up when on.

Next is to try the reverse. Have the plane flying flat and straight with the motor off and then go to full throttle instantly. If the nose drops then you have too much downward thrust (motor is too low in the back) and is pushing the nose down. If the plane noses up then you have too much upward thrust (motor is too high in the back) and is pushing the nose up.

Once you have these details worked out you can adjust the motor thrust angle by loosening the front motor mount platform screws and tightening the back or vise versa to correct it. Remember that center of gravity and motor thrust angles should be adjusted first to correct a problem before resorting to moving the trim. The goal should be to keep the trim flat and neutral because adjusting it otherwise will slow the plane down and waste energy. The center of gravity on a plane can also be used to correct slight climbing problems. For example, if the plane doesn't climb as well as you'd like with trim at neutral and the motor thrust angle is correct then check to see if the plane is nose heavy. If so, move the battery back a tad to compensate. Vise versa for a tail heavy condition. Some prefer the plane to climb at a steady pace at full throttle and will adjust the trim or the above accordingly. Others prefer the plane to fly straight and flat at full throttle. I prefer it to climb at a good but steady pace at full throttle myself.

If the plane tends to pull a bit left or right on you with the flaps flat and neutral this could be caused by one wing being heavier than the other (try balancing the plane on something and see which way it tips) or one wing having more flex in it. If neither problem is present to correct then the motor mount might be slightly off center. Move it ever so slightly to correct the condition. Again, while neutral trim is the goal and all the above methods should be used to try to correct it there are still times when trim is there for that very reason. Use it if you have to.

Motor options: If you are going brushless there are too many options to cover. However, I prefer going as cheap as possible and believe a brushless motor shouldn't cost more than $20 or $30 regardless of how good it is. Luckily many on the way past the limits threads have found cheap outrunners motors that are well under $20 yet deliver performance of motors costing $50 to $90. The two most popular brushless motors for Strykers are the BP21 or the newer 12T outrunners. These motors are made by Tower Pro and sell for around $15 or so. I believe the BP21 is model number 2408-21 and the 12T is 2409-12T or something similar. They can be found through numerous internet outlets.

The BP21 on a Stryker works best with an APC 7x6 Slow Flier (SF) prop and will draw well under 20 amps on it using a 3 cell lipo. A 2000ma 3 cell 10C lipo will handle it well (Check Dymond Motorsports or Common Sense RC for some cheap packs...don't pay for a name). Do yourself a favor and buy the 30 amp Tower Pro brushless ESC to feed it. More amps than you need but it will allow for motor upgrades in the future.

To figure out the amp delivering ability of the battery you need use the C raiting and the capacity of the battery. For example, a 10C 2000ma 3 cell lipo has a 20 amp continous amp deliverly capability. Don't rely on the burst C raiting of the pack to cover yourself. Also, most agree you should only be drawing about 80% of the amp ability of the pack. In other words, that's 16 amps on a 20 amp able lipo. This helps keep it cool and gives it a longer life with room for error.

The 12T motor is fairly new and has more power and speed than the BP21. The BP21 does about 80mph but won't do unlimited vertical. The 12T has more speed and will do unlimited vertical with the proper prop setup. Currently the three leading prop sizes people are discussing for it are an 7x7, 7x7.5, or 8x6E APC prop. APC props tend to be of better quality and less flex than some other brand names so seek out the sizes in them if you can. The 8x6E APC prop has less flex than the APC 8x6SF (Slow Flyer) and is said to give better speed and thrust. This motor is probably drawing close to 30 amps on the 8x6E so make sure you buy batteries able to handle it. The debate on prop sizes for this new motor still rage on so keep up with the way past the limits thread to see how things pan out. Mainly, most people are trying to find the best combination of speed and torque. The length of the prop (first number) affects torque (vertical climbing ability) and the pitch (second number) affects speed. Going higher on one usualy means having to lower the other in order to keep the amp draw within safe limits of the motor and/or lipo.

I'm using the best deal on lipos to safely power the 12T I've found thus far...3 cell 20C (with 28C burst) 2200ma lipos from RCHotDeals.com for about $55. They come with a balancing plug (As do the Common Sense packs above and perhaps the Dymonds now) that will work with the Astro Blinky Balancer ($25) I like to use. This balancer is about the size of a credit card and can be used before, during, or after charging. I prefer a charger that doesn't feature a balancing function so if one or the other breaks it's cheaper to replace. I like the Celectra 1 to 3 cell charger (about $45). The instructions for the Blinky balancer are weak so check the E-Flite power sources forum for a thread in which we went over how to use it. You also benefit from a stand alone balancer in that the battery doesn't have to be hitched up to a charger to use it.

If you buy the motor/ESC as a combo deal from such sources as Balsa Products, Aero-nuts.com, or RCHotDeals.com you'll get an even cheaper price (under $40 I believe). The only problem with this new generation 2 ESC is I haven't figured out to program it yet. Make sure you set the timing properly on the ESC (7 degrees for the above two motors I *think*) and the proper cutoff voltage (3 volts per cell) for a lipo. Also to make sure the cell count is set correctly. As for brake functions I prefer no brake because brake is harder on the motor and uses battery energy to freeze the prop in place (all three motor wires are powered to freeze the motor when off). Having no brake also allows the prop to swing freely out of the way on landings to avoid being broken. If anybody can walk me through the weak Ching-lish instructions for the 30 amp Tower Pro ESC I printed off the net that'd be great. I don't want to risk taking this new bird up until I'm sure it's set properly.

By the way, the above plane weighs in at 26.7 ounces. The stock bird is around 21 to 23 ounces. Not too bad considering the mods I did. I'm sure you can get the weight much lower by not pouring the glue on like I did (I don't skimp), using smaller magnets and/or metal on the other contact points, using thinner control rods and/or throwing away the clevises on the servo horns and using a Z-bend there, using plastic clevises at the flap horns instead of steel, cutting down the height of the flap horns if you are only using the bottom hole, not painting it as heavy as I did, using a little less tape under the motor mount (the rods should be more than enough with just a little tape), cutting down the ESC throttle plug wire's length because it's much longer than need be, replacing the PVC tube in the motor mount with a lighter plastic like a film canister, etc.

There are also various ways to improve the speed of the plane by making it more slick in the air. Some people go as far as to sand down the fake foam air intakes in the front so the plane is more streamlined. If you look at the plane from the front those fake intakes are the biggest wall against wind flow over the body. You could even stick some plastic cones on them to improve airflow if sanding makes you nervous. Back in the day before Stryker hatches were vented people used to drill out the fake air intakes at an angle to flow air into the battery chamber. Unneeded in my opinion as long as you have a vented canopy and back cover. If using the back cover that has an X-port mounting tube on it you can also drill out the bottom of the tube to aid in airflow. I believe it acts much like a carburator venturie (sp?) effect and draws air out of the cover as faster air flows through the X-port tube. Others have sanded the entire body down to smooth out the dimples and make it slicker in the air. Still others have placed an elastic material over the finger holder holes on the bottom of the plane to allow you to squish your fingers in there to throw it but have it flex back flat in the air to streamline the belly better. You can even cut down the zip ends on the aileron hinge holders so they don't stick out so much. I prefer to leave them as is to help avoid road rash on the belly. At first I had concerns they might snag on landing and rip out but I've had no such problems. To further streamline the plane you can sand down the nose to a sharper point or replace it with a sharper nose cone off some other jet type plane. Somebody did this in the past (name escapes me at the moment) and it looked really good and improved the speed as well. If anybody has a photo and part name please post it. I can't let this paragraph or thread pass without mentioning the infamous pool noodle mod. What's that? Another worthy idea that was spawned on the Dark Side threads...Go up to Walmart and pick up one of those pool noodles that is made out of foam and used by kids to play in the pool. This stuff is spongy and will form back to it's original shape after being squished. If you grind it down in a grinder or something you can make nose that will have more cushion to it than the stock one. Just don't let anybody see you doing this or you might end up in a rubber room.

I like my Stryker a little on the heavy side because it performs in strong winds better. In short, it's very easy to get a brushless motor/3 cell lipo setup to weigh less than a stock bird because they and standard electronics should weigh much less than the stock electronics/motor/battery. And, as you can see above, there are many ways in which to improve the slickness of the plane for faster speeds as well.

One final tip on electronics installs. I'm no expert on this but I think the Stryker configuration is of elevator and aileron. Plug the servos into the two ports on the RX that are designated for this. This isn't always the rule so it might take some experimenting. The radio is usually set up for Delta wing or some other form of mixing to get the servos to move properly. If your radio doesn't feature the proper mixing you can buy a seperate mixer to plug into the RX for around $15. As for the proper flap movements simply refer to Parkzone's online F27 manual to see which way they should move with various inputs. Don't be fooled into thinking they should move in the same fashion as a V-tail bird such as a Challenger or Extreme or you'll get a nasty surprise when you try to fly it.

Here's a simple F27 parts list with prices that should be about right: Body and nose come together for $19, 3 piece hatch set is $4 to $8, fins are $7, ailerons are around $4, motor mount is around $4. Not too bad a price to build such a great plane.

wildjaych

thanks for taking the time to do this........awesome!!!!!!!! answered a ton of questions for me.

critterhunter

I updated this thread to correct things and add more details.

critterhunter

Once again I've updated the messages in this thread to correct errors and add more detail and content.

critterhunter

Yet another new segment has been added to the above thread, mainly dealing with proper soldering procedures for the battery and ESC Deans Ultra plugs. I'm hoping that's the last bit of tweaking I have to do to the original messages.

billz

CritterHunter,

Thanks for doing this! This is great information that is relevant for all current models of the stryker. Great job! Have you ever thought of putting this together into a PDF file (an ebook) with all the pictures? I'd buy it for a resonable price :-)

Bill