Flight of the Yak

I put together a $22 Hobby Lobby Yak 55 Profile this week, and it’s great fun. This is by far the most aerobatic plane I’ve flown. Here’s my power setup:

Kit: Hobby Lobby Yak 55 Profile
Motor: EMax FC 28-22 from HobbyCity
Prop: 9×3.8 APC Slow Flyer from Some Dude’s Hobbies
Speed Controller: 30 amp Tower Pro brushless speed controller
Battery: 1200mah 3S 30C Li-Poly from HobbyCity
Servos (3): Hextronik 5g servos from HobbyCity

Here are a few videos of it in action

The takeoff

Sorry about the shaky cam at the beginning. Notice that it just jumps vertically out of my hand while rolling at about 3 rolls per second. Pretty awesome:Some Stunts

This video shows lots of fun stuff, knife edges, loops, snap rolls, flat turns. Lots of good stuff.Landing

This one mixes in some fun rolls and then the landing. The landing is a tad abrupt, but it works. I need to work on throttle management in my landing approaches because it just falls out of the sky if you dead stick it.That’s all for now. Stay tuned for more photos of the plane up close so you can see how I put it together.

23 comments to “Flight of the Yak”

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  1. Nice!
    I see you got yourself a little 3D-machine as well
    I bought one today, just for fun since I don’t have anything to drive at the moment: the super cub is boring now, and the christen eagle needs a gear and the 2 other one’s need to be built so I bought an Ikarus F3A shockflyer with a brushless engine. Started putting it together today, so I hope it will fly very well, first plane I’m making with no help at all so

  2. http://William says: -#1

    Dave,

    I have a super cub for 2 months now. I have been flying stock and enjoy it a lot. You did a lot of cool mods and video on the super cub.

    Hobby City has a wide selection of products. How did you find out the suitable brushless motor for your Yak from their selections?

    There so many selections in the park flyers market, and I still don’t know where to go next after my stock suber cub. Whether to do some mods to make it more interesting or move onto a suitable next plane :)

    I could not see the video on this page. There is a red x in the box that seems like the url cannot be found.

  3. William,

    The best way to figure out which motor to go with is to first decide which plane you’ll be using. After that, you can search around forums to see what others have used, and what has worked well. One thing I like to do is this. Say I want to figure out what kind of Hobby City motor people are putting on, for example, the Park Zone Stryker. I would do this google search:

    stryker site:hobbycity.com

    That would then show me all the pages in hobbycity.com that mention the Stryker. That’s how I found lots of great motors for the Stryker before.

    As for the videos that you apparently cannot see, those are YouTube videos. If they are not working, try clicking on these links instead:

    http://youtube.com/watch?v=SjleYXvKp4Q
    http://youtube.com/watch?v=HPISfegunwg
    http://youtube.com/watch?v=_WHHx64CudA

    –Dave

  4. By the way, I *highly* recommend the ParkZone Stryker as a second airplane after the HobbyZone Super Cub. It is so very fun, and is easy to handle for a second plane. Be sure to use low aileron travel on your first few flights though. You can buy the entire airplane (minus electronics) for $40 in parts. After that, buy the motor, servos, and li-poly battery from Hobby City. It’s a great plane.

  5. http://William says: -#1

    Dave,

    Thanks a lot for the site searching tip to locate the motor from hobbycity site. That is cool.

    It is an interesting idea to get the Stryker air frame to build a plane out of it. Since its fuselage, wing and feathers are “integrated” in one piece, the cost of the part is lower than conventional planes.

    I do not have transferable radio equipment. Have you been using DX6? Do you like it?

    I was thinking of getting the Parkzone T28 as it is quite popular as a 4 ch trainer and it has scale look. However, your Stryker idea is interesting as I would need to get good transferable electronics eventually as I move along with this hobby.

    Thanks for the tips/ideas.

    -William

  6. William,

    I have the Spektrum DX6 and I love it. My friend got the DX7 (which costs $150 more), and it’s fantastic too.

    I was looking at the T28 Trojan as well, but decided against it because I wanted a good radio that I could use in other planes. The DX6 is programmable, which means it can fly pretty much any airplane or helicopter. Besides, once you have a DX6, you can buy the plug-n-play version of the T28 and use your DX6 to fly it!

    –Dave

  7. http://William%20Lui says: -#1

    Dave,

    Getting a DX6 into a T28 PnP should be a good first model building exercise. I think will keep my holiday season spending in check and make this happen in January :)

    Then building the Stryker like you have done will be a good next exercise afterward. I will probably like to look at the manual to see how to program the 4 channels. I didn’t see movable rudder control surface, so I thought it would be 3 channels: one channel for throttle, 2 channels for eleverlon mix.

    -William

  8. You are correct. The Stryker only needs 3 channels. In the DX6, you program it for “delta” mode, and you plug one elevon servo into the receiver’s aileron channel and the other into the elevator channel. Works like a charm. If they go the wrong direction, just reverse the plugs.

    –Dave

  9. Dave,

    I have been flying the Super Cub, it seems everyone finds your site when googling the cub, and noticed you got the YAK 55 3D. I have been looking at this plane for a few weeks now. I ordered a new DX7 ($170 – ebay) and itching to get into the aerobatic flying soon.

    Hpbby-lobby has the YAK 55 plane on sale for $16 and the 400XT brushless motor on sale for $20 (seems like people love these motors). I really appreciate you listing your parts from hobby city, looks like they are drastically cheaper. Now that you have had a few months on the YAK, just wondering if feel good with your choices or would you suggest going with the hobby lobby motor/esc instead?

    What flight times do you get with the 1200 battery? One thing that kinds bugs me with the cub is the 10 minute flights. I have ordered the 8 cell 1500 elite for the cub, hoping to bump up the flight time. For the YAK I would like to get the 1500 mah or 2100 mah 3s lipo to maximize flight times. I was hoping you could give me some “expert” advice on the battery size/weight. I obviously don’t want to put too much weight on the plane. Ten minutes seems too short for me, twenty minutes would be perfect.

    Thanks in Advanced!

    -Kevin

  10. Kevin,

    With my 1200mah battery on the Yak, I get about 10 minutes of flight time. It feels much longer since the plane is so wild to fly.

    If you get a heavier battery than that 1200mah pack, your Yak will probably not fly at all. It needs a very very light battery.

    I am very happy with my UnitedHobby/HobbyCity motor. It’s still going strong, and for $5 how could you go wrong?!

    By the way, I’ve heard that a 2100mah lipo pack for the Super Cub makes for 20 minute flights and makes it fly much much faster. Have you considered that? They cost about as much as the 1500mah elite 8-cell packs.

    And back to the Yak, I definitely recommend the 9×3.8 prop for the Yak. I’ve also used a 10×3.8, and while you get a bit more thrust (just barely), the flight times are much shorter.

    –Dave

  11. http://Kevin says: -#1

    Ok, good to know…I will just go with the setup you suggest and buy a couple of battery packs.

    I have been going back and forth on the battery for the Cub, I went with the elite batteries simply because I don’t have a lipo charger yet. I know you can get a lipo charger for $30, but I didn’t want to buy that then end up needing a better charger. I know I will stay with the smaller, light electric planes. I have been leaning towards getting the DuraTrax ICE charger…but it does not come with a balancer or an AC power supply.

    I will mainly charge batteries at home, but would be nice to have the option to recharge in the field. I have also been considering the Accu-cycle elite but I see it will only handle up to 3 cell Lipo and only does up to 2 amps vs. the ICE goes up to 8. Honestly, since I am yet into LIPOS…I have no idea what I will need in the future, maybe those limits wouldn’t matter to me. I would be interested in your conclusions in regards to charging (which charger/balancer/etc).

    One last question regarding the YAK….the hobby stores carry each and every part of the Cub, so if you break something, it is pretty basic to fix. With the YAK, do you just buy a whole new kit if a part is not able to be tapped or glued back together?

    -Kevin

  12. I love my $35 HobbyCity charger. It has a car cigarette lighter adapter so it works great for field charging:

    http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=2055

    It does need a $30 power supply for charging at home.

    If you break your Yak, you just buy a whole new kit, because the whole kit is cheaper than most Super Cub parts! :)

  13. http://Kevin says: -#1

    Maybe I should get your email address, I think you have mine, so we don’t get too crazy on the blog.

    I am getting ready to place the Hobby City order, trying to get everything I need in one order. This will be my first real build and not a RTF kit. I usually buy props for my local hobby store for $3/piece. I see HC has them for 89 cents:

    http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=5292

    People say it takes a lot of work to balance them…it sounds like you stick to the hobby store props. Any prop shaft adapters I need to buy from HC, or did you go with the Hobby Lobby adapter?

    I really appreciate you taking the time to help me get going!

    -Kevin

    P.S. the charger is out of stock at hobbycity.com, hoping it doesn’t take too long for them to get some more.

  14. I bought the prop adapter at HC. You have to match the prop’s shaft width with the prop adapter. You definitely want a wobbly adapter for the Yak. Otherwise, you run the risk of breaking the prop on every landing. The prop is so big that it hangs down below the front of the fuselage. This is what they look like:

    http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=4507

    I would buy several of different sizes (at only $0.52 each, why not?). :)

    I’ve never balanced a prop, so can’t help you there. Happy Yaking!

    –Dave

  15. Oh, and be sure to buy the wobbly adapter that is more “conical” in shape (like the link I posted above). Do *not* buy this kind:

    http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=4323

    This kind doesn’t let the prop wobble very much at all.

  16. http://Kevin says: -#1

    Dave,

    I installed a prop saver on the cub, with an upgraded o ring. I am using the 1500mah battery upgrade. When I go full throttle, the prop shifts off the saver. Wondering if you have run into this, and what the work around might be. I have even tried using 2 o-rings, yet it still happens.

    I am using the style you suggested from hobbycity although I purchased it from a local hobby store.

    Any ideas?

    -Kevin

  17. I wonder if the conical part of the prop saver is not quite deep enough for the depth of your prop shaft?

    –Dave

  18. Also make sure your prop is balanced.

  19. http://Kevin says: -#1

    I went around to a few hobby shops here in phoenix, none of them carried a prop balancer. So I just used a long drill bit to hold the prop, and what do you know, it is slightly off balance. I have 3 props, so I checked another one and it was balanced (unaltered) and gave it a go on the prop saver. It worked great even at high RPM’s. I will test it in flight tonight when I go out.

    The 3D yaks arrived today, unfortunately hobbycity hasn’t shipped my electronics order. They are holding $150 worth of stuff because the 45 cent prop saver isn’t in stock ;( I have tried emailing and calling with no luck to just have the prop saver removed from the order.

    I was actually coming to your site now looking for those famous build pictures and instructions you provide….but I am not seeing them for the YAK. I was just curious if you used the CA glue, or epoxy, and what you used to attach the ailerons.

    -Kevin

  20. Kevin,

    I glued the Yak fuselage and wings together with CA. Be sure to practice on a few pieces first because it’s tricky.

    I used packing tape and the 3M Blenderm tape for the ailerons and rudder. It works great and is very easy to work with.

    Be sure to set your control throws to *very* low on your first flight, like less than 25% of what they say to do in the manual. The Yak is a tough plane to fly, and it was my 5th. I’m convinced that the ParkZone Stryker is the perfect second plane.

    Happy landings!

    –Dave

  21. http://Daniel says: -#1

    Hey Dave, Ive been reading this blog for a while, ever since I found it researching the O’l Super Cub. So, like Kevin, I decided to try out a YAK-55 as well.

    Let me tell you, this plane has been a curse! haha. After most the error being attributed to ME ( un balanced prop ripping the front of the plane off, prop saver snapping and sending prop flying 200mph at my head etc. ) there is one last problem that is killing me. Since I’m using the same hardware as you, maybe you have an idea as to what it could be.

    My biggest problem is that the ailerons have a “spasm” and lose their center position and will suddenly think they are in neutral with one flap up and the other down, and then my plane goes into a spiral of death. I’m using the servos that came with the DX6.

    I am new to the DX6, maybe the servos are no good but my YAK-55 is now in a dozen pieces. Its a silly problem because the plane flew GREAT when the servos worked properly. I simply did one roll and the ailerons would not go back to neutral, it was a short trip to the ground from there.

    I’m going to order a new Yak-55 and try it again. I just dont know if it is the servos ( most likely ) the transmitter or receiver.

    Thanks for the blog!

  22. Daniel,

    I’m sorry to hear about your poor little Yak! I know how you feel. It’s frustrating that one small mechanical failure can totally destroy a plane.

    I imagine that was your servo’s fault. It probably has a stripped gear (or several), and as a result, the gears jumped teeth and re-centered in a new position. I’ve heard several people tell me that those servos are cheap. I’ve actually had one fail in exactly the same way you describe, but with my Stryker, doing about 50mph. It ran right into a tree. I threw away that servo. I have found that the 9g servos from Hobby City are fine, and they don’t tend to fail in such a harsh way. Rather, they start clicking first and that’ll be your warning.

    Also, I had my Yak-55 aileron servo fail, and I was still able to land it on rudder/elevator. It was nerve racking, but I did it without damage.

    Good luck!

    –Dave

  23. Dave,

    I just got home from my first successful fight with the YAK….man, what a thrill. This was not my first attempt at flying with it, I actually had 3 really bad crashes with it which required me to completely rebuild the nose section. The first mistake I had made was my aileron servo was reversed. So on those 3 failed flights, the plane took up in the air so quick, started to roll left and with a little right input the plane went into the ground with a loud thump! While I was describing my flight to the hobby store, they told me to check the servo…and it was reversed! I guess this causes a great deal of crashes for us noobs. I had the servo freak out after the crash, thinking it was bad…and it turned out that if the servo is not in the correct position, if it is leaning and not making a good 90 degree angle with the push rod it will hum and not return to a good position easily.

    I also took advice from a guy online, and picked up FS One to practice with. This allowed me to experiment on the sim before trying it on the real deal, which helped me a lot. The whole hand launching thing makes me nervous, as too little throttle will cause the plan to dive, too much and you better have some quick reflexes! I built some landing gear for the YAK, which allowed me to have a smooth take off, and get enough altitude to trim it out. It was crazy cool watching that thing roll and flip around with authority.

    All was going great until my ESC cut the battery. I pulled back on the elevator and manage to get a descent landing in the dirt with only minor damage. This being my first lipo plane I am curious how the ESC works. When it cuts power, do you cut throttle quickly then give it some juice to return power to the throttle to land? I checked the battery and it was at 10.38V, seems like a high cut-off since you are supposed to be able to run down to 9V. The flight lasted about 10 min before the throttle cut-off.

    Hobby-Lobby charges the same amount if you buy 1 or 2 YAKs. So I bought 2, so once I got good I could fly the second one. The first one has been glued together in 2 or 3 parts and I had to completely rebuild the nose…but that is the great thing about foam, it is easily repairable! My landing gear did not survive the quick landing, so need to find some good gear for foamies.

    I am getting ready to place a 2nd order from HobbyCity, so good to know about the servos…I was going to order a bunch to have on hand for future planes. I flew the cub after the YAK and it was like everything was moving in slow motion, what a difference.

    -Kevin

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