somegeek

My Feedback: (2)

Broke my posts outta the huge past the limits thread for reference for someone pondering this build.

Thanks to folks on the board for the feedback for this build.

Bare fuselage, fins, hatch kit, aileron material, hinges, 2-56 hardware picked up at LHS.

Hitec HS81-MG servos and HFS-04MG reciever ordered from Tower Hobbies along w. single conversion ch 52 crystal.

hexTronik 1700mAh 11.1v 20-30C Lipo Packs and hexTronik Balancer/Charger ordered from unitedhobbis.com for $101 shipped.

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Used a heated screw to create holes for the rare earth magnets(picked up at True Value Hardware). If you use this method - approach the foam slowly at first. My screw was pretty warm as it started to melt the foam from 1/2" away. Waited a few seconds for it to cool more then created the holes for the magnets.





I poked the toothpick I used to apply the epoxy into the foam holes a bit to give the epoxy more to grip. Got the magnets secured. After 30 minutes I placed a piece of saran wrap over the nose cone and mounted it on the fuselage and then secured the nose cone w/ masking tape.

Waited 5 hours and then checked to see how it set up. When I removed the nosecone, the magnets from the fuselage side came with. DOH! The torn out fuselage magnets were easily removable from the nosecone magnets as the saran wrap kept the two pieces from bonding but they were too strong to be secured by the small spot of epoxy in the foam... fiberglass time.

Cut out small strips of 1/2 oz. fiberglass cloth to the shapes of the flat surfaces in which the magnets holes are. Filled the holes with epoxy - installed the magnets and smoothed out the epoxy that squished out and glazed the surface for the fiber glass pieces. The pics look like more epoxy is on there then there is actually - I squeezed out the excess epoxy from the glassing.





Tested the result this morning and it's very solid! No worries about these magnets coming out.

Also glued the canopy snap piece in place.



Sanded the sides of the clip before securing with epoxy so it gripped a little better. Trial fitted the canopy pieces to verify the depth to install it before applying epoxy.

Got the balsa TEs mounted so I have something to mount my balsa ailerons on.

Trimmed roughly 5/16" off the TE of the aileron positions using a ruler and straight edged razor blade...



Fitted the 5/16" stock and then sanded them a little on the top and bottom to taper them towards the wing tips...



Balsa TEs mounted and drying...



Build is coming along...

Glassed the top and bottom of the balsa trailing edges w/ 1" strips of 1/2 oz fiberglass cloth. Applying the epoxy glaze was done by hand. Wore a latex glove to smear it on - worked well.



After cutting the hinge slots w/ a hinge slotting tool I installed the ailerons w/ Dubro pinned hinges...



It's 1.25" aileron material.



I had to sand down the top and bottom a touch to match the height of the balsa TE.

Pieces are just fitted for the moment - won't secure hinges w/ epoxy until I paint it.

Woot - got a 12V power supply to power my Lipo charger (22A max on the 12V feed)- modified an old 300W enermax power supply...



Info on how to modify a PC power supply here. Links in the left frame at the bottom.

Batteries and charger should be here in the next few days. Should be looking to get my bird in the air next week! Just need to square the engine mount situation away.

The stock heat sink that comes with the Aero-Nuts BLC30 is pretty light weight - both in cooling and weight so I figured I'd replace it with some better sinks. I used a straight edged razor to cut the shrink around the edge of the plate and then removed it. It's the thin piece of aluminum held on by some gummy thermal adhesive. I was suprised after I removed it to find that the middle row of chips was not making contact with this plate! Only had impressions from the outer rows of chips in the adhesive.



I had some copper heat sinks left over from my PC overclocking days so I cleaned the heat sink surface with some windex and then used some arctic silver thermal epoxy to mount these on the chips...



They covered the 12 chips almost to a perfect fit!

The bottom side that was not heat sinked has four FETs on it - thinking of throwing a few heat sinks on these as well... at the same time, folks run these ESCs without modifying them so I imagine these bottom FETs don't get too hot. If they do, I'll sink them too.

Picked up two of the new F27C mount yesterday at the LHS - man - these are nice. Seem to have a lot of support from the number of mounting screws...





To mount my 2409-12T brushless I made up a piece to go inside the mount and sanded one side down for my wires to go through...



No worries on the thrust angle.

Got my engine mounted...



Had to file out a little more room for the wire and also extended the shrink a little so the wires would not rub through on the plastic edge.



Pondering taping off the front of the mount or capping it with something so it doesn't act like a wind scoop. Was pondering a rocket cone.

Lipos and Charger showed up today from United Hobbies in Hong Kong..



Had to pick up a cigarette lighter outlet at Radio Shack and fit it with some bannana plugs so I could hook it up to my 12V power supply...



Had one deans plug male side for one battery. Need to pick up a few more of those. Least I can fiddle with my servos now.

This morning I got my fuselage wiped down with 91% isopropyl alcohol and then put on a good layer of 3M 77 spray adhesive. Thinking I can maybe paint on the first coat tonight. Have the fuselage and nosecone hanging in a closet with my server - pretty warm.

Ordered two E-flite 3mm Prop Adapters w/ collet - part no EFLM1922 & some Female Deans plugs to get the $10 minimum order for the free shipping. Woot! Saves me a 90 minutes driving to the LHS that has the adapters. Won't need them until next week anyways. Imagine they paid for themselves with the gas $ I saved.



Got my pieces painted...



Fuselage will get one more coat...

Sprayed the nose cone and fuselage with a light coat of 3M 77 before spraying with the color.

Used Krylon Fusion River Rock and Krylon Fusion Patriotic Blue. The river rock needed to be shook up during spraying or you'd see some dark spots. Only happened a few times but was noticable and shaking the can after every 10 passes helped.

The spray adhesive left more of a texture than I thought. The paint went a ways to fill it in though to smooth it out. Also noted that any fiberglass cloth that did not get fully coated with epoxy shows up.

Hung them up in our laundry room which has an exhaust fan. Warm place to dry and no fumes in the house.

Heated a nail and melted some holes in the airbrakes to add some air flow to the battery compartment. Thinking of glassing the vents so they are more sturdy... the heat slightly deformed the outter edge.



Was also curious regarding the vent holes at the bottom - with air going straight past them - would they do a better job if they had something deflecting the air into them? Hacked up a toothbrush package piece...



Could almost open those holes a little more and really get some air up in there.

Not being familiar with how warm the batteries get - trying to think of ways to improve the cooling.

Also pondering removing a small strip of shrink from the sides of the lipos to get some air flow between the cells.

I was less than impressed with the finish I got from the 3M 77. Sure it's durable after the application of the Krylon Fusion paint but after putting on the paint it looks really like light sandpaper - not super smooth. Sanding a coating of rubberized adhesive would turn into a mess I think. It's not that bad but I was expecting something smooth... though with that coating and the glass - this will be a durable bird in the air and on those rough landings as I'll be learning on this one.

Added copper heat sinks to both sides of the ESC yesterday for good measure...



Some pics here of the initial heat sink removal.



Got my elevons installed last night... installing epoxy with hinges can get a little tricky if you put too much epoxy in the hinge gaps first. I would insert the hinges and watch for excess epoxy to squirt out - if it did, I'd pull the hinge and clean the excess and re-insert. After pressing the elevons into place there was still the risk of a little epoxy getting onto the hinge joint so I put a small amount of petroleum jelly on the top and bottom of each hinge and worked it in. Worked great.

Guess mine is on the heavy side - will be around 24.5 oz flight weight. Parkzone states 22oz for the F27C flight weight. Looking for rigidity as well as durability on this build. Will get my rough landings in with this one and build the next one for speed similar to Buggy's build.

My stryker is starting to look like something that will fly...



Those fins were tight going on - sprayed some windex on the bottom edge of the fins and they went in easier - that stuff will evaporate.

I used 2-56 hardware to build my control rods. Fitted the threaded ends w/ a plastic clevises until I can purchase metal ones. Only had two of the the solder on type at the moment. Gonna trim off the excess horn material once I know what holes I will be using permanently.

A dremel is the best hobby tool around - 'sides a Visa card. Cut off the horn screws flush...



Regarding balancing - I tried balancing the plane on the dimples in the bottom handle of the plane and it only balanced if I placed the lipo at the very front of the fuselage bay where I would need to remove the short angled foam wall that is roughly 1" from the front of the plane. It looks like I need to remove that short wall so I can slide the battery all the way forward - is this something folks have to do sometimes? I don't want to add weight to the nosecone to get it to balance.

Cut out the front short wall using a straight edge razor. With my gear temporarily in place, my lipo sits about 1/4" from the front wall of the inside of the channel. I have some room to move the battery back or forward which I am happy about.



Unfortunately this battery position won't take much advantage of the airbrakes I turned into vents but I did open the three forward fuselage floor holes to one big one.

Might install the scoop on the bottom with some fiberglass and epoxy... gonna wait and see how warm the battery is after a run.

At the back I melted the grove to the same size to the back of the channel so my wires fit under the cover for the most part. I plan on braiding the three wires - read this helps minimize radio interference? Do people also twist their battery wires?



Taped the hinges for better performance from my elevon controls using some 1" clear tape...



Sometimes it's funny how your brain works to make something more difficult than it actually can be... was looking at the stencil I cut out and how I was going to use it with spray paint and then went to the kitchen drawer picked up a sharpie and got to work to draw it on vs spraying...



Pretty happy with how it turned out...



My stryker is not a A, B or C so I figured Feral27x was appropriate...



The Ultracote went on really well. Keep your iron just at the temp the adhesive activates at - take longer at a lower temp and you'll be fine. The adhesive on Ultracote activates at 220F. I kept the iron on the ultracote avoiding any direct contact with the painted surface on the wing and kept running over it applying good pressure. I put a strip of clear tape across the front of the wing edge where the stripe ends for good measure.

I ironed on the stripes on the fins as well with not much trouble at the lower temp.

The Corsair Blue Ultracote damn near matched the Navy Krylon Fusion paint so that worked out well.
Added the battery strap(velcro). Cut some 3" strips - melted grooves about 1/2" deep in each lower edge of the channel where the battery sits and worked some epoxy into them then inserted the velcro strips. Battery can be snugged down tight with the velcro so it won't slide - pretty solid.



Used the silver cover for the ESC until I get a new style black cover...

Put two rare earth magnets on the front of the hatch. Had to balance the cover just right so the magnets would not shift outta place while waiting for the epoxy to set up. Also cut off a corner of the hatch clip so I'd clear the battery wires.



Gonna install a few t-pins or an L shape bent nail shaft for the magnets to hang on to to keep the hatch in place.

Finished my hatch last night... Trial fitted my hatch to see what kinda footprint the magnets made and cut out that area to that depth. Took a 1.5" nail, cut off the head and bent it into a U shape - like a staple. Used a heated pin to melt some holes and remove some material to mount it in at a 45º angle to get into the main structure. Used a needle to work epoxy into the holes and across the mounting area. Inserted the metal U.



Put some tape over the magnets on the hatch to prevent any excess epoxy from the U from bonding with the magnets. Installed the hatch and then wrapped with tape around the nose so the metal U would dry at the right depth and position since the magnets were already holding it in the right position/depth while taped. Left overnight - works great! Very solid.

My Hitec Channel 52 72Mhz single conversion crystal showed up today. Got it installed - programmed my ESC...

3 cell Lipo
mid-brake - helps with landings, gliding and less broken propellers
7º timing - optimal from what I've read - any higher overworks the engine risking failure
3V cut-off - highest the ESC has

Had to reverse the throttle on my Tx. Ended up blowing some cards off the counter in the kitchen across the way! Man - this thing is loud. Had to resist any throttle ups since this is not moving - no air cooling stuff. This thing is ready for a maiden...

Regular rates are 1/4" throw which works well. Have 1/2" set for dual rates - have not used this yet.



somegeek

somegeek

My Feedback: (2)

Replacement nose cones will not use magnets - will install nails and keep the magnets on the fuselage.

Picking up a new fuselage in the next month or so to start building a fast bird. Learning on this currently built stryker. Next will be built for speed/rigidity vs durability.

somegeek

somegeek

My Feedback: (2)

Adjusted my servo horns and trimmed accordingly to get rid of the excess. Used side cutters to snip off the end and then a sanding drum on a dremel to shape...



Control rod is on the 3rd hole from the end of the servo arm - trimmed off the 4th.

somgeek

somegeek

My Feedback: (2)

I think this scoop idea works well... brought the plane down from a mostly wide open throttle(WOT) flight and the battery was cooler than it's ever been...

I used a piece of a toothbrush package.

- cut it to shape
- roughed up outside with 180 grit sand paper so the epoxy would grip better
- melted the three hole vent into one large one to direct air onto the edge of the battery
- put down epoxy and poked several holes into the foam for the epoxy to grip
- covered outside of scoop with layer of epoxy and placed on fuselage
- placed a piece of fiberglass over and set in place








Since my batteries sit in the fuselage on edge and forward of the stock battery slot, the side vents I melted into the fuselage do very little to hit the battery to cool it. This bottom intake directs air up directly onto the edge of the battery. I carefully cut away the shrink on the sides of the battery to promote airflow between the cells. I covered the front of the intake hole in the fuselage to restrict the incoming air to the footprint of the holes in the shrink. Works great! Pondering cutting off the side vents(modifed airbrakes) in time and glassing over to aid speed.



On my rough landing last weekend the retaining snap on my cover got some cracks in it. CA glue worked great to bond the crack. The CA actually melted the plastic a little as I had some black residue on the tip of my CA bottle. Think this repair is really solid.



I've been messing around with different props. Took some pics to show the different profiles of the props...



The props that came with the Aero-nuts 2409-12T were GWS EP8040(8x4)...



These are flimsy props. I can imagine that under throttle these flex a bit causing some loss of thrust(I say imagine cause these lasted a day on my plane - not much time on them ). I'm no physics professor but this is my guess. Not a really fast prop but imagine you'd get a lot of flight time since it is not a very aggressive prop for these setups.



I have not flown a lot on this 8x6E but I do know it's pretty fast and really drains my battery quick! I need to get a radar gun to really measure the performance.



This 7x5E does a good job of moving the plane without draining the battery too quickly.



After running 12 batteries worth of flights with this plane the 6x5.5E is my favorite prop. Good speed and long flight times. Was checking out some charts for BP brushless motors at PeakEff.com and the charts show the sweet spot for efficiency for these motors using 5-6" props. The performance of this 6x5.5E today convinced me of that.

As you can kinda see in the pics, the APC E props are really built to be rigid resulting in less flex and doing a better job to push the air vs bend.

somegeek

somegeek

My Feedback: (2)

One thing I will say about the APC 6x5.5E is that you better give it full throttle after you throw it... been putting some flights on this prop and it does not have the inital thrust of the APC7x5E or the 8x6E. Takes a few seconds to get up to speed but once you are up to speed it's decent. Swapped props tonight and going to put more time on the APC 7x5E. Imagine I'll have more thrust from the launch than the 6x5.5 but shorter flight times due to the increase drain on the battery.

Had a good evening of flight... went to the local school where I usually fly and it was a no go(football game). Drove a few miles to a large field with nothing around it by a golf course. Got my plane up in the air and flew two batteries worth. There is a road that parellels this field so I was pacing cars or outrunning them when I opened up. They were only going 40-50mph but was still fun. Gonna see what kinda flybys I can get on the 7x5.

Pondering a motor upgrade...

Currently running - Aero-nuts BM2409-12T
Dimension : 31.0dia. x 62
Voltage : 12.6V / 3cells Li-po
Max Current : 20A
Mas Power Output: 200W
KV : 1600rpm
Number of stator : 9
Eff. : up to 70%
Weight : 65g

Upgrading to - Aero-nuts BM2908-10 (Delta)
Dimension : 36.4dia. X 51.7 (mm)
Voltage : 7.2V~12.6V
Max current : 25A
Max power output : 250W
KV : 1100rpm
Eff. : up to 90%
Weight : 91g

Thinking this 2908 would swing an 8x6 or 8x8 nicely.

My ESC is good for 30A and my batteries can handle a 34A draw(20C) so this 25A pull should be okay.

somegeek

somegeek

My Feedback: (2)

I taped the front of the engine mount to try to deflect air so it would not grab the air so to speak... was pondering a rocket cone and then saw critter getters setup and figured I'd get to work adding one to my engine mount. After looking for materials for a while I figured I'd try a different approach. A chunk of a 2-liter bottle. Seemed to fit well. Cut out a tab on the front to stick into the back cover and then taped on. Will prolly paint and then remount using clear tape. All air goes up and over with this setup.



somegeek

somegeek

My Feedback: (2)

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somegeek

My Feedback: (2)

Gonna kick it up a notch. Going to build this motor - the KH-278 V2 Single Stator with 7 turns and an APC 5x5E prop.

Kit reference image:


Can't knock it for $21 + shipping. Dude on another board said this should pull 26A WOT with that prop at 7 turns. Should be a perfect fit for my setup. Plus it'd just be plain cool to fly on a motor I wound.

Got my Komoto 278v2 motor wound today with 7 turns of 21.5 gauge... was a learning experience.





Learned a bit how the wire would and could lay on the stator. Next engine winding will look cleaner. Continuity checks with my multi-meter shows no shorts.

Just need to buy some motor plugs for this to connect and it's testing time.

Someone with a similar motor said this should pull 26A at WOT w/ a 5x5. Just what I was looking for. Wanted max performance for my ESC/Battery setup max of 30A. 26A is comfortable.

Motor kit is a Komoto 278v2 w/ 21.5 gauge wire.

Amped to try this motor out.

Rewound my stator with #20 - less resistance.

Turned out pretty nice I think... using the GWS prop as a winding packer made all the difference to pack the winds.





I packed the windings when it got tight as I was adding adjacent winds and then at the end when all teeth were wound, I walked the prop pieces around the teeth which pressed on both sides of each tooth at the same time which helped quite a bit.



Tested clean - no shorts.

Time to get this assembled for installation.

Got my Komodo 278 V2 build completed and installed. 7 turns of 20 gauge wire. Put on a 6x5.5 and throttled up for a few quick bursts and the throttle is linear from 0 to 100% and runs smooth across the board. Time to buy an APC 5x5E and test this baby. 5x5 should put the draw of this motor at 26A.











Maidened my Komodo motor today... zooom! It's faster than my 12T for sure but not sure by how much?

Setup:
Komodo 278 V2 single stator motor wound with 7 turns of 20 gauge wire in WYE configuration.
Aero-nuts BLC30 ESC w/ custom copper heat sinks
Hextronik 1700mAh 20C 11.1V Lipo
APC 6x5.5E prop





The wind today was working against me since it was blowing perpendicular to my flight path pretty good and rolled my plane up or down a little as I flew so I was weary of flying too fast when low, but a few flybys were enough for me to see this flew faster than my Aero-nuts 12T. Vertical was hot - climbed faster than my 12T. Just need to get a radar gun now. After flying around for a bit at higher throttle I landed and the motor was quite cool. ESC was warm. Batteries were warm but not hot. Prolly didn't hurt that its 50ºF outside. :P

Looking forward to flying this with no wind and also trying an APC 5x5E. Wondering how much juice I can put through this motor. Picking up a tach and a watt meter soon to figure out how things are looking with different prop loads.

Liking this motor - promising results!

somegeek

vasek

My Feedback: (4)

nice pics somegeek!

i am new to E stuff & just want know why the flowerpot over the lipo when charging(?)

pls check one:

- it helps to keep the battery cool while charging
- your cat likes to eat li-pos for lunch so you have to protect it
- you hide them because lipos are so expensive your sister steals them to buy makeup...
- i have no other ideas why

somegeek

My Feedback: (2)

I charge the lipo in the flower pot and store the batteries in an ammo box. These lipos can cause bad fires if they flame up while charging or while stored. Do some searches for lipo fire videos or threads regarding lipo safety and you'll see what a small nick in a cell can do.

I do have one battery that got a little tweaked in a crash that I still run but that experience made me look closer in to charging and storage safety. One battery having issues and left along can burn down a house if you're not around when things go south. Not everyone does it and maybe I am a little paranoid but I'd rather be safe than sorry.

somegeek

critterhunter

My neighbor garbage picks scrap metal and I gave him the heads up to watch for any heavy metal junction box or something I could store the batteries in (I'm paranoid as well). He ended up garbage picking me an ammo box. The thing was pretty rusty so I gave it a quick sand down and painted it with red paint. I plan to put a warning sticker on top of it to not move the box without keeping it perfectly level and flat. I'm worried somebody with move it around and cause one of the lipos plugs to brush against the metal and ground out in some fashion. I've also been considering drilling a few vent holes in it should a pack explode. Not sure if that would be better but having a feeling it's better to vent any gases than have the box blow apart. Opinions? May also line the box with cardboard to prevent any shorting problems.

somegeek

My Feedback: (2)

I saw a movie of different lipo storage solutions and they'd hit the lipos with a hot overcharge current or the like to get them to light up. The ammo box with a single 1/4" vent hole was the best solution. Just vented out. I have a towel in my ammo box to pad the lipos from the sides of the box - no worries.

Regarding your plugs - what kinda plugs you using? Use of the Dean's female plug on your lipos should remove any doubt of them shorting on a metal surface.

somegeek

critterhunter

Yep, of course I'm using female deans ultras. Just the same, even with a good heat shrink tubing job on the plug wires I still don't like those things getting near any kind of metal just for precautionary reasons. Will drill a hole in the box. Thanks for the info.

somegeek

My Feedback: (2)

Wrote this up for a PM so figured I'd post this here as well for future reference in regards to the hardware I used for the control rods on my stryker.

2-56 threaded rod - has 1" of threads on one end.

2-pack 2-56 Steel threaded clevis

2-pack 2-56 Nylon threaded clevis

2-pack of 2-56 rod solder clevis

2-pack of control arms

There are also 12-packs if you want to get extras.

If you're not familiar the 2-56 is the thread/shaft size. Can buy small hardware the same size like screws and nuts at a local hardware store.



I did a plastic threaded clevis on one end and a solder clevis on the other end. As long as you sand the 3/8" of clevis that will be soldered in your clevis, the solder will grip well. Also heat up the clevis enough so you see the solder melt and flow in to fill in the clevis tube around the 2/50 shaft sp you see a filet of solder on both ends of the clevis tube opening.

You can also use some kind of metal polish or car polish in a rag to polish the push rods to a chrome-like shine.

If you're not down with the soldering they sell full threaded rods so you just have to screw on the clevises. I find though if you go this route you'll need to get some 2-56 nuts to tighten against the metal clevis so they are tight otherwise they kinda rattle but just a little bit.

I also cut down the servo horn to the first hole and I have enough throw to have to adjust the EPA so I'm not throwing the control surfaces too much. Basically have room if I want to turn up the throws a bit.

somegeek

avalentine

I'm new to the stryker, but have been flying wings for years. I just bought a bare fusalage, fins ect. I want to paint it but am leery of the paint attacking the foam. Can you put the Krylon directly on or do you need to put something else down first?