Kris' GP Yak-54 buld thread

[KrisW]

Actually, I'm using the BME44,which was the original small single BME offered up to about 3 years ago. It's lighter than the BME50 by some 6-8 ounces, but also not as powerful. I'm trying to keep the engiens displacment near what Great Planes rates the plane for .. tying not to go with a 50-55 cc engine, just to show how well the plane flies/doesn't fly with the proscribed powerplant.

When the BME 55 comes out I'll be getting two of them. One will more than likely find it's way into this plane.

All in all I expect this plane to fly rather well, though. i'm already hauling out some higher priced lightweight parts, like a smaller ignition pack, lighter 2400 ma receiver pack, and looking at a CF spinner I have on the shelf that ought to shed 2 ounces or so.

Best of luck with your Cap . it looks like a beauty.

[3-d flyer]

Hey Kris.... lookin good! Gett'in close huh? I just ordered a D/A-50 today, was lucky enough to get one from Troy Built today as they just recieved some this morning from D/A. Talked to Brian Huff today and he said they are still 3 weeks out yet, so i feel fortunate i was able to nab one! Chief's back order list on the 50 is a mile long they tell me. Sooooo, the D/A-50 is going on mine, can't wait 2 months for the BME, even tho i've got one coming also, it will find it's way in another project.
Thought i would chime in to give my solution on the stab install....
I was not crazy about their setup, so here's a trick i learned a couple years back with the GP Patty Extra,
On the bottom of the Yak there is a open area just under the stab,(the rest of the fuse is solid. I just positioned the stab as per normal tip to tip measurements and then "tacked" it with thin c/a. Then turned it over and neatly poured a 1/2 shot glass of epoxy on the stab/fuse sides.... made 2 perfect "fillets" .... then after cure, i mixed another small batch and syringed some over the top of the stab and let it run down.... end result.... STRONG!!!!
I feel much better about this now, now i'll just throw a small white patch on there and it's done! I'd post a pick but i have to resize it and it's a PITA!
Can't wait to hear your flight report..... any guess on how long? and any chance you'll get some vid of it?

[KrisW]

Weather permitting Jeeum and I are gonna maiden the lil beast next Wednesday, and shoot video and pics of it. I'll have a full flight report, with mixes, good and bad tendencies and overall flying characteristics right after that. Also gonna fly some IMAC with it, and see how it handles precision manuvers.

I got the elevator linkages finished on tail this evening, installed the Fuel dot, and changed the BME44 form a stndard 14mm plug to a CM-6 10mm plug by using a threaded adapter ring sold by BME for that purpose. Now, after changing the engines timing form 28 degrees BTDC to 2 degrees btdc I can run the new Falkon ignition that BME provides with their engines. I also received the 21-8 prop that is proper for this engine, as well as a new carburetor. All were installed and are ready to go. All that's left is to synchronize the elevator servos for equal throw at 50 degrees deflection of the elevators. . and mount the cowl. I dislike using the provided cowl ring, and long 4-40 wrench, so I am going to install hardwood mounting blocks and use that method to retain the cowl

[KrisW]

Well, I'm playing hooky from work today (Sunday). gonna have 64 degrees, 2-4 knot winds, lots of sunshine, and DAMMIT ! ! ! ! I want to go flying.

Only thing left to do is match the elevator servos, test run the engine, and finalize the CG (install the rx battery. . ), then go out and maiden this thing.

[3-d flyer]

Awesome! Can't wait to hear your flight report!

[SleepyC]

Well..... whats the story??

Whats the deal.... your last post was at 9:43 am....
Its 5:00pn.. enough time for anyone to maiden a plane!

[KrisW]

	Quote: Originally Posted by SleepyC
	Well..... whats the story?? Whats the deal.... your last post was at 9:43 am.... Its 5:00pn.. enough time for anyone to maiden a plane!

Well l l l l l.. . . . . I had to fix it so I could fly it. .

[ShortBus]

What happened?!?!?!

[GremlinX]

Well? Oh the suspense...

[KrisW]

Okay ..EVERYONE wants a flight report.

Well, things weren;t 100% as smooth as they could have been. Had a few engine problems concerning carburetion and the fact that the engine didn't have very good ring seal because it had only been run a few times and then sat on the shelf for almost 3 years.

BUT. . get it running we did, with a decent idle of 1500-1800 rpm and good smooth transition and top end.

The first flight showed a few things. first off, 2 clicks of up elevator and everything was decently trimmed out. CG was set 1/4" behind where GP advises it. . no biggee. I got the feel for the plane during basic flight movements like rolls and loops, then started looking for problems with mixing and other issues with the basic flying qualities.

First of. .Engine thrust is PERFECT as set from the factory. Do not mess with it.

Secondly, in KE it requires about 10-12% mixing rudder-elevator. The plane tends to tuck to the belly slightly.

Third. . in KE the plane tends to roll out of the KE slightly, so a little bit of aileron is needed to hold a perfect KE pass.

Fourth, in the wind (about 5-8 knots today, variable) the tail gets blown around a bit with a tailwind, but everything tracks pretty well otherwise. At lower speeds you have to use a pronounced AOA (it's noticeable) to fly a straight line. Being that the plane is a little heavy, this is to be expected.

Elevator, rudder and aileron authority are VERY good. Roll rate on a vertical line is SILLY. . like 2 rolls/second in either directin. The same for downlines. It's possible to drop a tip (again, because of the weight) on a hard pull at low speeds. Snaps, if the speed is kept up, are decently clean and precise. Do not expect them to self recover, You have to counter control a little, due to the weight, to stop the fuselage from yawing at the exit of a snap.

Slow speed flight, if kept sane, is very smooth and manageable. Stall is straight forward, and it's easy to initiate a spin in either direction (wind permitting). The break is not very sharp, so popping the nose up at the last second should give you a good hard break if you desire one. Landings, if you do not get the plane too slow, are very smooth and manageable, with no bad manners. You can flare the landing pretty deeply without dropping a wing. Get too slow, however, and you WILL be repairing the gear plate. I had this happen on the 2nd flight, after changing to a very low pitch propellor (22-6), and was not able to "fly" the plane to landing (OOPS. .I screwed up). The Plane hit pretty flat, but the right side of the gear plate broke loose. I'll have a "how to make the gear plate stronger" post in the near future. BTW. .Takeoffs are very quick and smooth. The plane is off the ground in 20-25 feet if you desire it, with no bad tail wagging on throttle up.

Overall performance. . The plane tracks very well, especially at 1/2 throttle or higher. 45's (with the CG set to factory specs) are straight, with just a hint of nose drop when inverted. Inverted (again, factory settings) is smooth, and just a littel down elevator is necessary to hold inverted fight. Vertical lines track well, with no pitch or yaw problems noted. Downlines are the same way. You may need a little bit of down elevator mixed in, but I did not see a need for it during the 3 flights today. The fuselage weight is the weak point on this plane, with the plane tending to pendulum in the yaw axis on the exit of snaps. The rudder is VERY effective. . I'd advise 40-50% expo on all rates.

After I did a temporary field repair to the gear plate, I got in a 3rd flight. I'd made some mixing changes (as outlined above) and bolted the 21-8 prop back on. Witht he speed back where it should be the plane flew much better with the new mixes dialed in. On point rolls it is necessary to FLY the plints. Just banging them will result in the plane wagging the tail. The plane can be flown very smoothly, if you move the controls deliberately instead of just thrashing things around. I flew last years IMAC Advanced sequence with the plane. It performed very well in every manuver, with my familiarity with the plane being the limiting factor as to how well it flew the sequence. A little more dialing in of the rates and expo would also help. it snaps VERY well, for its size, if you keep the speed on and don't throttle back during the snap. It proved a little more nose heavy than I like for a couple of the 45 degree lines, but this can be adjusted with CG movement.

Now. . I was going to review this plane as a starting point for Basic and Sportsman. I give it a VERY enthusiastic two thumbs up for these classes. ANY pilot who practices with this plane will be VERY dangerous in those two classes. He can fly in closer and tighter, use less of the box area, and the plane will do every manuver better than the majority of pilots in those classes can fly. In other words, the only limiting factor for this plane, in IMAC Basic or Sportsman .. even Intermediate, is the Pilot himself.

Would I recommend this plane. . YES!!! For basic Sport flying and even IMAC it is a good plane. I haven't done any 3d with it yet, but given the stall characteristics of the plane, and how well the controls work, it's going to be a good one.

How would I improve the plane? It could use a slightly thicker wing, the rudder is actually overly effective, the gear plate needs to be beefed up, and the weight needs to be reduced. But, that's nitpicking. For the gearplate. . Don't crash it you silly boy ! ! ! for the weight, be careful what you put into the plane. I'm going to go to smaller batteries and a CF spinner and mini throttle servo to shed 8 ounces off the airframe. Toss in a BME55 instead of the heavier 50cc engines out there, and this plane could easily see the high 13 lbs range if you are careful. Right now the BME44 is all the power this plane needs, even at roughly 16 lbs wet on takeoff. But, when you are flying every ounce you can shed is better IMO.

So, have at it guys. Jeeum shot some video of the planes 2nd flight. Do NOT use this as repesentative of the plane performance. The prop sucked the life out of the plane because it did not pull hard enough and the plane could not get any energy built up in order to fly properly. When I bolted the 21-8 back onto the BME44, the plane came alive and was just a blast to fly.

[GremlinX]

Thanks, Glad all went well!

[3-d flyer]

Good Review Kris! Glad too see it went well.... I was guessing the gear plate was going to be a weak point, I too am looking at beefing up that area as well.

Whats the all up weight on your BME? I am bolting up a D/A-50 on mine and i'm curious on the weight difference....Also for comparison sake what is the weight difference between the Fugi (recommended by GP) and your BME? Just looking to see if i'll be in the ballpark. I'm going to fly mine with the 50 untill the lighter BME comes out...