FlyStraight

I'm building the Yak 54 50cc and couple of issues came to mind that I like to discuss.

1) there is too much hardware included for rudder linkage hookup. Seems to me that there are two ways to mount the rudder cables. Either use the larger rc links for default two arm plastic horn or use the ball links for a larger carbon fiber or metal rudder horn. I think in the old version of the plane, they used the rc links and in the new they use ball links. It's confusing and aeroworks should throw one of them out, ie. rc links.

2) the L-shadped metal horns for flying surfaces are not precisely 90deg. bent and the pre-drilled holes for them are spaced too closely together so the two arms are close together. Ball link ball goes between them and the space is way too tight. Better quality control needed here.

3) don't include metal throttle with metal clevis pushrod instead include nyrod 256 for throttle with a ball link at the end. I have a spare and I'll use that instead.

4) manual doesn't state what that clear nyrod going thru the fuse is for. It's an antenna exit.

5) Should the rudder cables be crossed or not? Crossing them is better for geometry reasons. Have to try crossing them then if there is problem will go to uncrossed. What do people use? Manual is quiet on this issue.

Just couple of issues as I'm going thru the build. Posting a pic of too much rudder linkage hardware. The carbon and plastic horns are mine, don't come with kit.

FlyStraight

Also, should I use the plastic 2" horn or the larger 3.5" carbon horn? I want about 45 deg rudder throw.

Grelker

My Feedback: (58)

I assume you're building the 50cc size.....I would recommend the larger rudder servo horn. I used 3" and it was just about right.

You can use a metal throttle linkage as long as the connection to the throttle arm is plastic, either a ball link or clevis. I like to use a 2-56 ball link with 4-40 thread as the 2-56 link is a little smaller and fits better.

My rudder cables are not crossed.

Grelker

My Feedback: (58)

There is a great discussion of the geometry involved and a link to the SWB site with a graphic that is excellent. I knew i'd seen this, but it took me awhile to find it. Check this out: [link=http://www.flyinggiants.com/forums/showthread.php?t=8684]rudder geometry explained[/link]

Grelker

My Feedback: (58)

Here's the link to flying giants if the link above doesn't work for you as it didn't work for me.

http://www.flyinggiants.com/forums/s...ead.php?t=8684

the **** should be replaced with the web site address: www.f l y i n g g i a n t s.com just omit the spaces between letter. I did this to get by the censorship here at RCU

FlyStraight

Grelker,

thank you for that link, it was informative. I have the 50cc Yak and my worry with respect to the rudder geometry was with the rubbing on the cable exit holes when cables are not crossed. I should have been more specific, sorry.

I think I will use the larger horn and then investigate crossed or not crossed and cable exit holes.

I messed up my aileron and elevator horns mounting. The holes for the wood screws that hold the L-shaped horn to the flying surface were pre-marked not pre-drilled so I drilled them out with a 1/16" hand drill. After that I found out that the L-shaped horns were too close to each other. What I did on the rudder is I put a ball link between the arms to get proper spacing between the two arms and then used the horns as a template for drilling the holes for the screws. I should have done that from the beginning as illustrated in the manual and not rely on the pre-marked holes. This pre-marking of holes need to be changed in the factory.

I'm also using one of the best tools I acquired. It's a Great Planes engine mount hole hand drill for like $8. I drilled all the holes with this device, it's very sharp and in few turns you have a nice centered hole. I also put two drops of thin CA in the holes that hold down the aileron servos but skipped this step on the elevator and rudder. I destroyed one or two screw heads trying to put them in the CA'ed holes as the holes were super tight after the glue set. I didn't CA'ed elevator or rudder holes and I feel that there is enough meat on the screws to hold them in place. We'll see if the screws back themselves out after flying.

One other thing. There is very little wood on the fuse to hold the Rx heavy duty switch harness. The only location I think that will be suitable is right behind the main wing's trailing edge on that side wall plywood that is also a structural member of the tail. If I make a hole for the switch there, I'm afraid I will weaken the structure there and on heavier landing the tail might crack there. I wish Aeroworks made a pre-made holes for the switches as I've seen on other 50cc arf's. If I had more plywood I could make a plywood ring around the switch's hole to beef up that area. Seems like a lot of trouble to go thru for what should have been a simple switch harness hole. I don't want to put Rx switch near the cowl as there might be RF interference signal from ignition. Been told to keep Rx and switches away from ignition at least 12". Any ideas about Rx switch location?

Thanks.

bgw45

My Feedback: (1)

FS, cut a piece of light ply for the switch and then form it to fit where you need it. Too many different size and style switches for the maker to please everyone.

FlyStraight

I wish I had some lite ply. Might use glass cloth instead to beef the area around the switch harness or just cut a hole and leave it at that. Since this plane is a quick build I was expecting little more help from AW. Kind of like plug and play. I wouldn't mind buying what they recommend just so that I have less hassles designing out some flaws. Anyways, can't wait to get this plane in the air.

Grelker

My Feedback: (58)

FS - I mounted my switches up front by the cowl. I have used this location on every gasser I have and I have not experienced any RF problems, even before I switched to 2.4 in my planes. I also do not beef up the ply around the switches, hundreds of flights and no problems. I do use a ply backer plate on gas fills because of the force of pushing/pulling the fill plug into/out of the housing. I usually use switches with charge jacks and the wood has held up great for me. I did use a balsa backer strip on the Yak to fill in the space between the top member so the mounting would be easier. The blue tape on the switches is a remnent of the assembly; that's how I make sure the small nuts don't fall out. See pics.

rktman56

FS-
The rudder cables are designed to run straight, not crossed. Mark has been at the NATS the past week and I bet has been busy with other things to answer your post. But a quick call to Aero Works can put Rocco on the phone and he can explain why he designed the rudder cables that way if you have any other questions. When did you get your ARF? I've built two and each had the control horn locations pre-drilled. I'm thinking that this model is now in about the 9th or so production run! So each one I've built the horns all lined up with the pre-drilled holes. Again, when did you get your model?

On both of my 50cc YAKs, I got metal rods to use for the throttle in the box from Aero Works, not nyrod. Although I changed and used a piece of 4-40 threaded rod, over layed it with piece of carbon rod and used ball links on each end... simple, secure and easy. As far as the plastic tube, yes it's for the FM Rx systems antenna. I removed mine and cut off two short lengths to use with my Futaba 2.4GHz Rx antennas. Then just covered the exit hole with a small piece of covering.

Some companies like Hangar 9 and Great Planes (for example) have included cut outs in the sides of the fuse for switches in some of their ARF's. The holes from these companies ARFs also are the size of the electronic equipment that they sale. For example, Hangar 9 = Spektrum... Great Planes = Futaba. Yes it is true other switches do mount in those holes, but the idea is that "THEY" have set the location for those items. This is fine when you agree with the location and only need to enlarge the hole (if needed). BUT with this Aero Works ARF, you are in an entire diff class of ARF! Many modelers have their own ideas on what "they" want to use and where on the model "they" want it mounted. So many items you can use and so many places to mount them. For me, I mounted my remote on/off switch and charge jacks on the left side of the fuse by the cowl and the manual ignition on/off/charge jack and DA fuel dot mounted on the right side of the fuse by the cowl. Not saying this is the right thing, just it has worked great for me. The wood is plenty strong enough to mount the switches and but I also used a plywood backing when mounting my fuel dot.

Also remember that when you hook up your control linkages, they will not be at a 90 degree angle to the control serface when the horn is at 90 degrees to the servo. This is designed that way to ensure that the servo can give max torque at max throw. Rocco and the Aero Works team put all of their models through lots of desgin and flight testing. If you ever have a question it is very easy to talk to them. They have always been very nice and helpful for me.

Just my 2 cents... hope it helps.

FlyStraight

Grelker,

thank you for the pics of the switches, I might do the same to my model.

rkman,

I bought my yak June 20th of this year from Tower Hobbies. It was drop shipped from AW. The horn holes were not pre-drilled only pre-marked on my arf. Also, I got the engine mounted and cowl trimmed and rudder installed. On the engine, the DL 50cc firewall template that comes with the arf, does not fit my DLE 55cc engine. The four holes on the template are not spaced out enough. Also, the manual states to use 1/4" drill to drill the holes out and that drill size is too large for the 5mm bolts. I used 13/64" drill bit I think. Obviously, DA 50 is not DLE 55, but I read somewhere that they have the same mounting pattern. Maybe I remember wrong and that was between old DLE 50 and DL 50. Not a fault of AW, I'm just pointing out this problem for future builders.

I think I will in future add smoke system to my plane. So I decided to have lots of room around the gas tank compartment just in front of the main spar to mount two tanks side by side rather than one after another. I also wanted to keep the throttle servo away from ignition so I mounted it behind the main wing's spar in the pre-cut servo pocket, which was a great idea on behalf of AW. I'm not sure if they suspected some to mount their gear there or whether to have an exit holes for the servo wires, etc. Then I ran a long nyrod to the throttle on the engine. Glued at three points (where the masking tape shows). I skipped one glue point as it was strong enough. Not sure if the epoxy is going to hold the nyrod in place, maybe use a ziptie for safety or strands of gloss cloth to hold the nyrod to the frame. Will see how it holds up under vibrations. The throttle servo box that you get with the arf is great but takes too much space in the gas tank compartment if one wanted to have tanks side by side.

I also cut the cowl holes with a dremel and a small dia. cutter wheel. Very easy work but very tedious. I elongated the hole where the exhaust comes out so that I could slide the cowl on/off the plane easily. I also cut out a small lip from the front of the cowl for the front engine fins to clear the cowl. Using the standoffs provided with DLE 55cc, my engine is 6 3/4" from the firewall to the prop backplate. About 1/2" too long but ok. Seems the plane is tail heavy which is better than nose heavy for balancing reasons. Easier to add weight to nose than tail structually.

I have one request of AW. I don't have the correct allen wrench for the four landing gear bolts so I used locktite and locking pliers to tighten the bolts. It would be great if AW could standardize on the bolt sizes so we could have only few different sizes. For example, they could use the 5mm bolts not only for engine mounting but also for landing gear. Maybe for wing hold down bolts as well. Just thinking outloud.

I totally forgot about the extra wood they give you for the optional engine canister mounting and I can use that wood for the switches backplates if I decide to do that.

One other thing. I used a 1" C-clamp to squeeze the brass eyelet when I was securing my rudder cables to the ball links. As I was tightening the clamp the eyelet and the wire twisted in the clamp and the brass threaded rod got jammed. I did one more turn and the brass threaded rod snapped in two. Not sure if brass should do that but it was surprising because I didn't put that much pressure on the rod. Then it was fun unsqueezing the brass eyelet so I could get the wire out and replace a new brass rod. Thank god AW added that extra hardware in there You have to really squeeze out the brass eyelet to lock the wires in professionally. If you use the clamp like I did, you end up with a really solid attachment.

So far I would say trimming the cowl was the most tedious part after putting together rudder cables. I wish AW added a clear template that slips over the cowl with engine cutouts molded in. Or better yet, offer pre-cut cowl for DLE 55cc and std. muffler. I wish AW would put together the whole package so you don't have to do any work. If you want to use DA 50 then buy the DA 50 package, etc. As much as these arfs are advertised as Quick Built they are not. I think I spent two weeks now working on it and am 50% done. Anyways, I'll keep adding to this post if I come across something interesting in my built. Thank you all for suggestions and tips.

FlyStraight

Guys, sorry for the big pictures, my post is hard to read across screen. They're 1280x960 full size but I don't know why they're not thumbnails like the others.

FlyStraight

I decided to activate choke manually with a rod. I used 256 sized threaded rod with plastic clevis at the end. I made a Z bend in the rod behind the clevis to move it outward away from engine. Then I used four zipties, two ganged together, to form two figure 8 loops around the right engine standoffs. Then I used silicone fuel tubing and I put a red coffee straw into it so when the rod moves thru the straw bushing it doesn't bind on the silicone fuel tubing. Without the straw, there is too much friction betwen the rod and fuel tubing and the tubing moves and slips out from the zipties. There is about 3/4" space between the rod's handle and the spinner's backplate when choke is fully opened. I used the idea from the plane's manual and it works great.

FlyStraight

Couple more pics of the ignition installation. The black foam on top of the engine box is the 4.8v 2000mah hobbico nimh battery secured with velcro. Side to side movement won't eject the battery as it's held by foam so only one velcro strap is needed to hold it down. I've decided to install ignition switch up front on right side of engine and receiver switch up front on left side. Rx switch will be like 6" from the spark plug wire and I'm hoping that it won't interfere with the switch. I've built .60 size and smaller planes and this Yak is my first jump to big gas planes so everything is new to me. I've also finished trimming the engine cowl and it just slides onto the engine without removing the spark plug wire.

FlyStraight

Assembling the fuel tank:

I'm using three lines to the tank, the fill, vent and carburator lines. To bend the brass vent line I used an allen wrench that I put inside the brass line and bent it little by little, each time pulling out the wrench bit at a time. Same for the fill line. The fill line has a gas line attached to it and a small clunk at the other end. The clunk comes about half way into the tank so it wouldn't fight with the larger carburator clunk. I used all stock fuel tank hardware. The gas line is Sullivan 3/32" ID extra flexible line No. 208. Fits 1/8" fittings. It's perfect size, the same as the air line on the DLE 55cc engine that it came with.

I soldered barbs to both sides of carb. line, to the outside of vent and fill lines. On the inside of tank the fill line has a zip tie on the brass line but not around clunk. There are zip ties on both the carb. brass line and clunk side inside the tank. I had to borrow two barbs from the smoke tank that was included in the arf. I took resin core soldier then wicked the ends of brass lines with them then heated the soldier up and pushed the barb onto the brass line. Let it cool and put more soldier behind the barbs to hold them better in place. Then slid gas line over and zip tied it behind the barb. I forgot to put the fuel tank stopper washer on before I soldiered in the barbs so afterwards I had to enlarge the three holes so it would slide over the barbs which worked out great and I think it's better that way.

FlyStraight

Fuel system:

My friend gave me a tip. He suggested I put a loop into the carb. line so that there would be fuel left in the line thus it will be less hassle flipping the prop. over to draw fuel into the carb on cold starts, etc. So I did that. Velcroed the loop to the side of the engine box. Then velcroed the fuel tank to the bottom formers and took small pieces of velcro and attached them to the vent line then to the fuel tank velcro straps. Holds pretty good. The vent line comes out the bottom thru the bottom engine box former and it's zip tied to the canister former assembly. Comes out the back of the cowl so no fuel inside cowl. The fill line comes out of a hole under the Rx switch and it has a zip tie on both sides of the fuse so it can't come out or in. No fancy fill caps, etc. Don't like using T-fitting on gas line because I could be flooding the carb. A Y-fitting would work but didn't had one.

FlyStraight

CG, ignition, tailwheel:

CG:
I put everything on the plane and it weights 18lb 5oz. Stock muffler, alum. spinner, etc. To measure the CG I measured 4 1/4" per manual from leading edge at the wing tips. Took wings down, put wing tube in so wings were spread on the floor with just the tube joining them. I took a string and attached it to both wing tip ends then marked where the string came to the root of wing. Put wings back on plane and put fingers under the mark and my plane came out tail heavy. I had to place Rx batts. in front of the fuel tank to balance. The way I weighted the plane, I took a heavy duty string or rope and made a circle. Slid it thru the wing tube on both sided of the plane then put the wings back on. Then I used digital fish scale bought at Walmart to measure the weight.

Tailwheel:
I used stock setup but after while I noticed that the spring wire tended to elongate the hole in the plastic wheel arm. I couldn't imagined loosing steering on my paved runway as both near and far sides have chain link fences. So I took micro fasteners I bought for my parkzone radian but never used, and used them here. Works great.

Ignition and wiring:
I wrapped some wires in velcro to tidy them up. Used the soft side of velcro on the inside of wires. Some wires are also wrapped in velcro but also the formers. Then I can attach the wire to the former at any angle and the wires can also slide on the former but stay attached to it. I mounted the 42% opto-kill switch with a zip tie to the fuse former. Use fuel tubing on zip tie to cushion the tie joint. Zip tied the kill switch around the 3-prong wire plug, rest is hanging in the air. Hopefully it will stay that way, otherwise I'll wrap the switch in foam and zip tie it to the fuse former. I have a warning light coming from the switch out of the fuse hole below the ignition switch. CA'ed in place. The light wire can be unplugged from the switch if the switch goes bad and be replaced with new one, minus the light which stays glued to the fuse.

FlyStraight

I'm breaking-in the engine on the model on the ground and the vibration has caused wire chaffing of the Rx battery so I mounted it parallel to the fuse in front of the tank. Works better that way. Hopefully CG will be unaffected. Also on the pic you see my final radio arrangement in the fuse. Did a limited range check and no problems with the Rx signal.

One thing that struct me coming from glow planes is the large vibrations of gas engines. My plane shakes like crazy, but as I'm setting the needles and engine is breaking-in I find it to run a bit smoother each time. I'm amazed that the engine hasn't fallen off the motor box yet and that the servos continue to work despite the huge vibrations in the stabs. Vibration at half throttle is less but is more frequent. If you're new to gas engines as I'm, I recommed you break it in on the ground for at least a half gallon of fuel. Just enough time to get used to the needles and get the engine idling at 1600 rpms or lower. I'm running 32:1 gas/oil mix using Lawn Boy 2-stroke air cooled engine oil from Ace Hardware. Max rpms are around 7,000. Both needles were turned in the factory recommended settings then maybe half turn either way to fine tune it. The trick of a broken-in engine is to get the low speed low enough at around 1350 rpms and in such a way that engine doesn't bog down with fuel as it's pushed out of idle. It should run at idle indefinitely w/o quitting. I find the DLE 55cc engine can do this well and there's very little burbling at high end and it has smooth acceleration.

To start the engine, ignition is off, choke is on, throttle stick is two three clicks above idle. Flip prop couple of times to draw in the fuel. Turn ignition on, throttle to idle, choke on. Flip prop until firing is heard. Then turn choke off and flip the prop and engine should start. I wear a heavy duty glove and when flipping the prop, it's important that you go thru the motion from 2 o'clock pm to 9 o'clock am decisively, no hesitation or half flip as the prop could backfire. The first time starting the engine is scary as you don't know where the throttle opening is. Is it going to run too fast or not enough? Luckily my idle setting was ok, say about 2.5K rpms. I have a rope attached to the tail and also one of the landing wheels because the plane would dance from side to side on ground.

About the loop in the carb. line. I think I will remove it and test it. I don't like fuel sitting in there and stinking up my house. Hopefully engine starts will be about the same. The fill line is working great and it removes almost all of the fuel out of the tank. I do plug the vent line when in storage. When breaking-in the engine I think you should turn the needles on the richer side, engine still doesn't burble when accelerated but not lean enough to damage it. Hopefully this info will be useful to someone. Any engine tips, etc?

FlyStraight

Forgot to say, that the fuel tank and batteries were moving around when engine was run so I strapped them down really good, especially the fuel tank velcros. I decided to use the velcros instead of zip ties because I wanted to remove the tank fast for CG purposes, etc. I would have to cut zip ties on tank plus vent line everytime I wanted to adjust something. The tank sits on top of the rubber foam padding, not the soft kind for Rx but the hard kind and it's causing the tank to move forward before I strapped it down really good. I mean pushing on the tank from top, compressing the tank and the hard rubber padding under it. Now the tank doesn't move, the batts. are fine as well.

rktman56

You do not have to worry about flooding the carb when using a T-fitting as you are now. With the type of "pumper" carb used on DLE, DA and others for example , they do not allow fuel to pass back into the carb and flood it. Remember there is a diaphragm inside your carb that pumps fuel to the carb when the engine is running. This is not the story with nitro 2 and 4 strokes engines and allow fuel to pass into the carb and quickly flood it. The use of a T-fitting on these nitor types of engines is a poor idea. You are fine using it on your DLE.

Have you checked the weight of your plane yet?

What prop and size have you picked?

eagletalon

My Feedback: (21)

Hi`FlyStraight just want to comment on engine vibration and i`am just checking to make sure that you have the wings in place while test running your engine, but you may already know this. if not make sure you do or you will get excessive vibration. keep us posted on your build. and thanks for shareing.

FlyStraight

I did not know that the T-fitting will not cause flooded gas engine. Thank you very much for that tip. In future, I might put in a T-fitting in my gas line so that I could use the main clunk to empty out the fuel and to reduce weight of the secondary clunk that I'm using now.

The weight of my plane is 18lb 5oz last time I checked. I'm using wooden Xoar 22x8 prop that I bought from Valley View RC. Also got the alum. spinner from them. Both items had pre-drilled holes for the prop shaft and bolts. Very nice job on the drilling. The props even have the weight in grams written on them.

I'm using 4200mah Hobbico Hydrimax Nimh Rx battery and when charging it on my Triton EQ charger on Nimh settings at .4 amps it would falsely end charge. So I'm now charging it on Nicd setting at .4 amps successfully. I think they should be charged for 16 hours or 160% their C rating if using time charging. Later, I'll try to charge them at C/4, I think it'll prevent false charge ends, then push it to 0.5C on Nimh setting. Yesterday, my Rx battery gave up while engine was running and the opto-kill switch killed the engine. Perfect.

Oh yeah, I did not know you have to have wings on the plane when running engine on the ground. It would make sense that they would dampen the vibrations. I'll try that out. Thanks.

FlyStraight

The only thing remaining to do on my build is to break-in the engine more so it vibrates less and to put on the engine cowl to see if the cut outs don't interfere with the engine and ignition wires as the engine is run. Then I have to set the control throws and I'm ready for maiden. The arf comes with a paper angle measuring device that I found out you tape to the top of the vertical stab to measure the rudder throw. That's a neat idea. All in all, it took me about one month to put this arf together being my first giant scale plane and engine. Overall, I'm very satisfied with the AW Yak. There were few problems here and there so I tried to document them here for others. I've built 16 planes, mostly from kits, and 2 helis in the past and can work out the issues myself but I wanted AW to see them and maybe correct them in future kits.

Some issues:

1) hardware included from older versions of the arf in the new arf caused confusion ie. clevises vs. ball links and thicker threaded rods vs. thinner ones.
2) tail wheel steering springs biting into the plastic tailwheel arms
3) weird sizes of hex bolts for landing gear and wing bolts (usual allen wrenches in store don't have this size)
4) could supply extra rudder pull-pull wire in case something goes wrong and one can't undue the brass eyelet from wire
5) control horn holes marked but not pre-drilled, fluke in my kit?
6) included DL 50 engine template does not fit DLE 55cc, too narrow, go by the dimensions in DLE 55cc .pdf manual

These are some of the issues from top of my head. Otherwise a very good arf and would buy another one. I'm already thinking about their 35cc Extra 260

FlyStraight

I wanted to see the amp draw of my TS-170 servos. I have 5 of them and one CS-64 analog servo on throttle. The pic shows a draw of three TS-170 and the throttle servo max draw at 1.7 amps. I estimated about five 20 min flights out of 4200mah battery. The Whatt's Up meter is connected between the battery and the receiver to measure draw of all servos.

Grelker

My Feedback: (58)

fs: the current draw during flight will be more due to the airflow over the control surfaces. u can simulate this by checking the current draw of the rudder with no load. check it again and resist its movement by pushing back with your finger and read the draw, should be higher. i allow 300 mah per 12 min flight as a rough rule of thumb. if u don't have a separate ignition batt, it would be more. let us know your test results.