The Yak-9 grooves - Flight report

Okay, good day at the field. Last night I balanced about 10 props, most were pairs I bought so that if I found the right one, and then busted it, I'd have another. Most were APC, some pretty expensive, but I wasn't going out unprepared. I undid all of my fuel system mods and went back to the original wedge tank plumbed for standard venting to keep it simple.

After all the balancing, getting ready to turn in for the night, I was giving the Yak one last admiring look when I saw a 10 inch long wandering crack from the air scoop wing, and passing up and under the canopy toward the nose. Needless to say, I was horrified. I just turned the lights out and locked up. Then I sent poor ol' Cribbs a sobbing PM telling him about it. Sorry, Ron, I had to tell someone and I damn sure wasn't going to wake my wife up to tell her.  

The thing is, this is an epoxy laminated fuselage, so there is no way no how, that crack went any deeper than the center seam. So this morning before we flew, Wayne and I took a look at it in Watt's shop. I brought syringes and needles, filled one with CA, and while Wayne spread the crack I filled it with CA. And of course I got it all over the rest of the side of the plane and glued a paper towel wad to my fingers that I really thought was going to burst into flames. I wiped it off with acetone and didn't ruin the paint too bad, but did smear some of my red kill stars.

So out to the field we went. Last time out, I couldn't get it to hold a lean break without dying. That was with an APC 9x5 prop. Today I started with a 9x6. A small increment, but I figured it was better than making wild changes and getting confusing results. Also, this time i was using Powermaster 10/29 from a gallon that Will Davis gave me. It cranked much more easily and ran marvelously breaking in and out right on time. I did a few wingovers and some inside loops and flew inverted so Wayne could get eyes on it and see it's roll attitude. Tip down when flying upright and tip up when flying inverted... and no cutting off. By the time I was confident enough to do outsiders, I was worried about fuel, so flew it on out. It drank every drop, warned me for only one lap and shut off clean with no nonsense, and I managed a decent landing in the thick grass. That's when I was so excited I posted the above short report from my phone. And now I've got $40 bucks worth of props I didn't need, at least today.

Most of the rest of the day we worked on the FanFare, which I sometimes call the Windfare. That was Wayne's main reason for being there today. Heck, I'm proud to just be a part of that project. About 2:30 we got to a stopping point and walked down to the field for another go. We tried tweaking the flap to correct the roll, but I couldn't budge it without fear of breaking the flap. So I forged ahead anyway. It was about 20 degrees warmer and we burned a bunch of fuel adjusting the needle. I had to set it leaner. Had to think about it, but that makes sense. I was surprised at how much different it was from earlier though. I'll have to remember that if I ever fly this engine in a contest. But with Wayne's help, I hit it pretty close. I think it cruised a little leaner than the early flight, but it flew well, and i got some insides and outsides in. But this time it shut off prematurely... on an outside loop, but at the top, thank goodness, so I glided in for a landing. If it was tip high during the loops, that may explain the early shutoff. Anyway that was it for the day, I had a 50 minute drive back home and had to split.

I did get a video. BTW, this is the first time I've ever turned a loop with a flapped plane, and it's different. You'll see my difficulty hitting the shape. I also held them high on purpose. I was still fearful of bottoming it out. As she gets uglier, I'll get over it. And one last thing. The Fox exhales downright Snot! That was the greasiest mess I ever saw on a plane. Not a problem. I can see right off the bat why many stunt fliers love Foxes. I may now join the ranks of Fox lovers. I was skeptical at best before now.

So without any further Yakking, here's the video:

https://youtu.be/aqAWh_Lja0k

Cribbs74 wrote:Just seeing this now. So.....   or   

     

Very Cool Rusty! I'm glad the tank-work you did was a success. I know the thought of a clunk-tank on the Yak made you cringe...
I just went back and read that note from Will concerning your unplanned landing... funny stuff!   I also learned through this thread; what "greenies" are... I knew that somehow we earned rep. points... but I never knew how they were generated... or who gave them.

Rusty, I think your needle setting is very good. There's always the possibility that tank is not digging the hard maneuvers. Try opening up your maneuvers and making them larger and not so abrupt to see if it still quits. Did you ever get around to capping one of the vents? This as I mentioned before will increases fuel delivery. I just feel that the routing of the fuel system is the problem here. I've used that tank and experienced the same problems your facing right now on a Streak. Did you have the clunk tank with you? I would of love to see if that would've resolved the issue. Ken

Ken Cook wrote:Rusty, I think your needle setting is very good. There's always the possibility that tank is not digging the hard maneuvers. Try opening up your maneuvers and making them larger and not so abrupt to see if it still quits. Did you ever get around to capping one of the vents? This as I mentioned before will increases fuel delivery. I just feel that the routing of the fuel system is the problem here. I've used that tank and experienced the same problems your facing right now on a Streak. Did you have the clunk tank with you? I would of love to see if that would've resolved the issue. Ken

I had the clunk tank in the box, but since flying wasn't our main mission today, I didn't get any chance to experiment. I had the uniflow capped and the overflow open with a forward angled tube on it. Just two flights all day. You're right, I was flying tight. Mostly to stay out of the grass, still being overly cautious, but this being the first time I've ever looped a flapped plane it turned a little quicker that I expected. You saw in the video the first outsides that plane has ever done, and only the second insides too. A couple more flights and I'll loosen up. But I can say this, it's a very comfortable easy feeling plane to fly. Neutral is nice and steady and no different inverted or upright. Nice steady pull, and like I said, surprisingly responsive. I didn't get a time on my laps, but it felt about right. I do need to get it to fly with the wings level before I do anything else. That'll be the first thing I do next time out.
Rusty

Rusty,

By my rudimentary math you are about at a 5 sec lap time. I am happy that you had a good run.

Looks like the ship is very responsive! Hope you had a great day!

Cribbs74 wrote:Rusty,

By my rudimentary math you are about at a 5 sec lap time. I am happy that you had a good run.

Looks like the ship is very responsive! Hope you had a great day!

I did! And I also recognize the sound that Fox made when it was cutting out the other day. Though I changed more than one thing to fix it, the prop and the plug, the sound it made is not unlike the sound the Thunder Tiger makes when it coughs out... at the same times in flight. I'm going to try an RC long plug in it. In fact, I now recognize the plug that was in it when I got it. It blew after the first run and I replaced it with an OS8. It was an RC long. That fix would be a frustrating but welcome discovery. If that fails, the SS gets one of my my fp25s. My NVA and venturi will be in the mail today.
Rusty

I am still going to stand by the 10/22. I really think you should use it. It will definitely cut down on the slime.

Everyone will tell you to use 10/29. Even the guys I fly with gave me a funny look when I told them what I was using. That is until they saw how my engine runs were. Now they don't say anything anymore.

It's up to you of course   

Cribbs74 wrote:I am still going to stand by the 10/22. I really think you should use it. It will definitely cut down on the slime.

Everyone will tell you to use 10/29. Even the guys I fly with gave me a funny look when I told them what I was using. That is until they saw how my engine runs were. Now they don't say anything anymore.

It's up to you of course   

I didn't want to use 10/29. But I asked Will for a gallon of 10/22 for all of my engines, and tasked Wayne with getting it from him at the meeting in H'ville. Wayne came home with the 10/29 and said no charge.  
I thought of faking it but the PM 10/29 is an ugly shade of putrid super light greenish. That in itself worried me, but it runs fine, so I've got it now. I have a quart of Sig, I'll try just for comparison when my insistent mentors are away.

It's good that I didn't have to use a 10" prop yesterday. This plane has short LG and it looked like it didn't have wheels at all while sitting in the grass yesterday.
Rusty

Rusty,

It certainly won't harm the engine and believe it or not even Duke Fox recommended high castor in his products. Run it through that gallon and get that bird trimmed and then switch to 10/22. I bet you will notice a difference.

I just purchased a gallon of 10/22 and it is a nice shade of purple....   not sure why they are adding dye, but whatever. 10/22 and 10/29 used to be yellowish clear.

Condition of the engine is the main factor. Castor can make a tired Fox run better. The problem with the Fox .35 is heat. The case is extremely thin and unless the cylinder fits properly within the case, heat transfer suffers. The exhaust side of the liner can develop a lot of coking if all castor fuel is used and this will be expedited if the engine is run hard or cowled in. The carbon becomes so thick that it needs to be mechanically removed. It will keep the engine from running at it's peak performance. THis doesn't happen immediately or within a few runs. It starts developing problems like above when you have gallons run through them.

As for the Powermaster fuel, Powermaster was for the most part out of business. VP racing fuels essentially took over the fuel line. This is where the fuel color changed. I have done back to back checks with the older fuel vs. the newer fuel. I haven't seen any noticeable difference that would make me not use it. Ken

Very nice Rusty, Good job she looked like it would go where ever you pointed it . Nice flight video , have not read the whole thread yet but I will in time just now found it      Getback

I have to say the flight looked effortless and calmly carried out.

Apart form a little dance during take off you seemed to stay in one spot for the entire flight.

I enjoy watching skill levels increase. I don't believe it is just the model!

It's a surprisingly comfortable flyer, I'm pleasantly surprised. Just a couple of tweaks and a bigger fuel tank should get it running for a full flight. I'm liking the old style Fox type engine run. That 4-2-4 break is fun to fly and I love the sound.
Rusty

Yeah that sound is intoxicating. I have heard a lot of engines run, but nothing beats the .35 Fox bark!

Ron

Is the yak essentially a mustang? My club us having a Fox/McCoy .35 race in October and both planes are eligible. I would really like a mustang in my lineup,

Jim

Here you go, Jim. From Wiki:

http://en.wikipedia.org/wiki/Yakovlev_Yak-9

The Yakovlev Yak-9 was a single-engine fighter aircraft used by the Soviet Union in World War II and after. Fundamentally a lighter development of the Yak-7 with the same armament, it arrived at the front at the end of 1942. The Yak-9 had a lowered rear fuselage decking and all-around vision canopy. Its lighter airframe gave the new fighter a flexibility that previous models had lacked.[1] The pilots who flew it regarded its performance as comparable to or better than that of the Messerschmitt Bf 109G and Focke-Wulf Fw 190A-3/A-4. [2] The Yak-9 was the most mass-produced Soviet fighter of all time. It remained in production from 1942 to 1948, with 16,769 built (14,579 during the war).[3] The Yak-9 was the first Soviet aircraft to shoot down a Messerschmitt Me 262 jet.[2] Following World War II it was used by the North Korean Air Force during the Korean War.

I think a real Mustang would eat a Yak-9 for lunch. However in the Sterling kits, the F-51 Mustang is its sister plane, the models being matched for head to head slow combat. Lots of both have been built.

Here's the inspiration for my color scheme. I assume it's a post WWII racer:


Here's the sterling F-51: