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GW Yak 54

1497 Views 18 Replies 5 Participants Last post by  BIZZARO
GW Yak 54 Test Flight Report

First off, I have to again thank Pro Bro Alfster for setting me up with this Yak, and the guidance when finishing it. Thanks Bro!

The set up is as follows:
Himaxx 2015-4100 with a GWS "D" gear drive and a GWS 12x6
Castle Creations Phoenix 10 ESC
Kokam 3S 1500 mah LiPo (4 ounces)
Hitec Feather (gotta get a Berg one day…)
(2) HS-55 servos and (2) Cirrus CS-21 (HS 55 clones)
The Yak finished at 10.75 ounces without a battery.
CG at ¾ of an inch AFT of the spar
(Plug that into your MotoCalc!)

The plane launched just below half power, and slowly climbed out at about 10 or 15 degrees of climb. Once flying straight, trim was minimal. I flew a couple of 50 foot laps to get a feel for control response, then started to 3D the plane.

Everything was great, except the rudder. I may have some flex somewhere, as the rudder was drastically out performed by the ailerons and elevators. I'll re-check the set up, before the next flight.

Harriers are a natural for this plane. It will cruise along at power with a few degrees of up attitude. Even at 14+ ounces, the Yak could be flown very slowly like this. It didn't take much power to keep a walking speed flight going. Even at a shallow angle of attack and very slow speed, the yak felt like control authority was good enough to feel confident at low altitude. I throttled back and pulled into a clean 45 degree harrier, and it didn't take much elevator to hold it there. The wings did not seem to rock, even with the gentle winds of the day. Inverted, the plane was less stable, probably because of all of the weight of the battery now being over the plane. The pendulum effect wanted to roll it back over. After a few seconds of playing with the ailerons to find the sweet spot, it calmed down a bit and became a bit more stable.

Hovering was tough, as the wind would pick up a bit every now and then. It was hard to see what was the wind bumping it around, and what might just have been an instability issue. When the wind died, I felt like it was hovering all but straight vertical, and it torqued extremely fast. I'm thinking that in no wind, it was near one rotation per second.

The knife edge was good at speed, but at high alpha, the previously mentioned rudder authority issue showed itself. The Yak also showed very minor roll coupling following the rudder.

Waterfalls were fast, and needed a bit of rudder to keep straight, on the upward part of the rotation (the last ½). It wanted to fall off into a knife edge spin. I was using left rudder more times than right to correct.

Walls were perfect, a full 90 degree pop up and rock steady after that. There was no need for rudder correction in a wall. Even from a crawling harrier, the elevator would rotate the last 45 degrees and then start to tail slide. A burp of power got me a head high torque roll that, somehow, I didn't expect. I should have seen that one coming.

Snaps were pretty clean, and if held to full elevator and rudder, could be stopped deep in the snap, nose up in a hover. That's my favorite move with this one. Fly full power, and snap with full control deflection. Throttle back as the plane finishes the rotation, and hold the elevator and rudder. When vertical, let the controls center, and it will stop in a hover. It is much cooler than doing a wall into the hover.

All in all, the plane easily rates an "A+". Even if I never find any more rudder authority, the plane is great. As my comfort level improves, I plan to see just how low I can torque and hover. The plane acts like it's waiting for me to get better…

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Great flight report Frank !

Glad to see it worked out for you. Maybe we can fix that rudder authority. You have the first airframe that I cut out from the latest design-rework. I am building myself one right now. My original beta version came in at 14oz, and I was hoping that with the redesign, the newer ones would come in at around 12. The rudder is a fuzz smaller on the new design, may have to enlarge it again.

How did you finally decide on attaching your control surfaces ? If it was something easy, then a new rudder will be an easy installation. If it is permanently attached, it can still be fixed. Just add a 1" strip of foam to the trailing edge of the rudder.

After I get mine finished, and do some flight testing, I may have a better rudder design for you. If you need some foam, or an entirely new rudder, I can send you one Bro.

The more you fly that bird, the better it will feel to you. It is the most comfortable foam design that I have ever flown. Very confidence inspiring.

The Chuck Flyer feels a bit more agile, and I'll be building one of those as soon as Chuck gets off his sorry azz and sends me some templates. Must be a LONG walk to the P.O. from way out there on his goat farm.... :lol: , but this design flies a bit more smoothly I think.

Keep us up to date on your foam adventures.

Also, you may want to make sure you don't have a butt load of expo on the rudder. After flying Chuck's planes, I ended up dumping all my expo, and my planes came alive a bit more.

Later Tater !!
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As far as needing the rudder in a waterfall, I think that is a result of torque, but I could be wrong. My Sledge, and the EF540 need the same rudder input during waterfalls.

Maybe with an increased rudder area you will have the rudder authority you are looking for, but like Chuck has said, most foamies have TONZ of rudder authority usually. Possibly a balance problem still. Possibly lateral balance, but I think I would move the CG back about 1/4", and try it there. May wake it up a bit more. Anytime a plane is flying comfortably, the CG is too far forward.... :lol: :lol:

Be cautious about cutting a hole in the foam for the battery to mount centered. I tried that in the first few foam planes I built, and it usually caused more grief than it was worth. It weakens the fuse. I just mount my battery with velcro on the opposite side as my speed controller, and receiver to balance things out closer.
Y E S !!!!!!

The new one came in at 12 1/4 oz on the button, ready to fly, with a 3S 1200 E-Tec pack !

Same set of plans I cut yours from Frank, and I even added 1/4" to the tail surfaces.

Hopefully this rain will stop so I can put her in the air this afternoon to see how she does.

I'm not in the plane selling business Bro. One of the fastest ways to ruin a good hobby, and something that you love, is to turn it into a "job". Look what it did to Chuck. He made some bucks, but he wakes up in a cold night sweat at the mere mention of a CHUCK FLYER !!!! And, I've been waiting on a set of "hand drawn" plans for eons. Not gonna happen to me.

BUT, unlike our goat farming friend, I have these plans on the computer, and can e-mail them to you free of charge, and it only takes seconds, as opposed to MONTHS to get a set of plans !! Don't you just love this modern technology ? Someone needs to introduce Chuck to the year 2004. :roll:

If you want a set of plans for this plane, just send me a valid e-mail address in a PM to protect your address, and I will send them ASAP. The plans I have are in PDF format. One large sheet that you can either get printed at Kinkos, or tile into regular sheets with an appropriate graphics program to print and tape together at home.

The rain has not stopped, so I have no flight report on my new one..... :x

The good news is, at 12 1/4 oz, the Razor tries to yank it out of my hand at less than half throttle !! I have a feeling this one is gonna be SWEET !!
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I figured it would be MUCH more fun to just send everyone running to you for the templates, and bugging the PISS out of you for the rest of your life...... :lol: :lol:

I'm no CAD wizzzzzzard, by a long shot, but I can attempt to put the templates on the puter for ya Bro. Couple hours hard work, but once it is over, then sending plans just takes a mouse click.
You cranky old piece of shit farking icehole ! :lol: :lol:

I figure I'll get the templates about the same time as my retirement check ! hehe
You will ALWAYS be older than I am, unless you jump off a bridge before I do.... LOL
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