flat spin

The reed valves in some cases simply do not seat properly. They should seal almost perfectly but if there is more than 1mm i would say this could start causing problems. Mine were the top and left valves as tehy sit in the Yak and if either wasshifted to the bottom the engine would splutter and die almost immediately. This could be aleviated by running the bottom end rich but only to the point that you lost all responsiveness. Strange because as it would die it actually sounded rich. A freind of mine also with the Yak had similiar symptoms and found it hard to get the right mixture on the bottom only the bottom, i sent told him to check his and they were not seated properly. I sent him a new one which i had, the problem went immediately.

I am told by Toni Clark, DA's agent in Europe that if you simply remove the white portion of the reed block and turn it through 180 then they should automatcally seat properly. I honestly cannot see how this would be the case as it is all symetrical but it is worth a try. Hope it work for you.

Ricmussman

My Feedback: (24)

Wayne & Chip,

Thanks for all of your help on Saturday. Flying the EF yak was a real treat. I could not have done it without your help and encouragement. I hope Sunday went well for you at the competion, and Chip I am glad to hear you got to fly. Also thanks for the video of the maiden, although it was boring, thanks!

Others,

I had several small issues that all got resolved in time to fly. I need to get a good prop that matches the engine better. I was using a Beila prop that was a little small so vertical was limited. Although It flew great, power was nominal. On the second flight I had some engine difficulty, as it turns out the ignition battery was only showing 3.9 volts...[:@] so that night I changed it out to a fresh pack and put 4 flights on Sunday, and 4 more yesterday. I was having so much fun I flew it right out of gas on one flight. The glide rate is amazing and very predictable. It is a mazing how slow this plane can fly with great control. I still am flying it very conservative (higher altitudes) because I had to break the piggy bank to get it. I haven't messed with the trims for two reasons. One because my little stab twist is back and because I will be getting a different prop soon. I also had to lean out the engine a little more cause it was too rich. I am sure it will be great when all of the issues get resolved. I must say the plane is much better than the pilot, can't wait for this plane to help me get to the next level.

Thanks Chris for a great plane, can't wait to show you it at XFC (Congrats on making the field).

coche

My Feedback: (4)

bodyworks, have you check your fuel lines, fuel tank?

CHassan

My Feedback: (13)

I have a DA and have somewhat the same problem. High G's or quick bumps and it bogs down. I keep an extra click of trim on the throttle and have only had 1 dead stick from it. I don't have the slowest idle but it sits still on the runway. then once in the air I add the extra click, just to be on the safe side. When I get ready to land I give it one clik down on the throttle, if I remember, if not then it still lands fine.

On another note, I had one bounced landing monday and noticed the paint has cracked on the gear. This kind of scares me becasue I can't tell if it is the paint or the gear. Has anyone had problems with the gear?

Ricmussman

My Feedback: (24)

CHassan,

I had a "68 Yak and they were notoriuos for paint cracks. Fortunatley it was just cosmetic only. Unless the landing was really rough, I would not be too concerned. You might want for some more opinions though.

CHassan

My Feedback: (13)

The landing wasn't that hard, just landed in the wrong spot, our runway has some rolling bumps in it, I hit on the up side of one and it kind-of bounced up and settled down nicely agian. So far all the other landings have been smooth as silk.
I've never had gear of this material so I don't know what to expect realy.
Like you Ric, I streached my $$ to get this plane and I'm being very conservative with it so far. (Although I do like the low knife edge passes [>:])

stomper

My Feedback: (20)

I was out flying Saturday and left my throttle trim to low and ended up deadstick. It was windy and at the wrong end of the field so I had to land with the wind.
My the time I reached the end of the runway the plane looked like it had slow down enough to turn before hitting the tall grass at the very end of the runway. Wrong The left leg just folded under the plane. I got lucky as not a scratch on the plane to be found.
This landing gear is built with CF rods on the leading and trailing edge of each leg but stop right at the top bend of the gear which makes for a very week and poor design! As well there are very few FG fibers running though this area. Mostly just glue.
Called TNT and they will be shipping a new Alum. gear this week.

Matt Wheeler

I delaminated the gear neat the axel on mine. It does not like side loads much. It did not fail to the point that it was not useable just un-sightly.

Matt

vertical ts

My Feedback: (50)

With an aluminum gear you might have pulled the plate out of the fuse.I think the stock(carbon) one did its job.Just my opinion.

rmh

Well -I still have the stock gear - was not going to sell it -but changed my mind
anybody need it?
$20 bucks and US mail charges - $5.00
No foreign shipping!
By the way -If you use the aluminum gear -you can break the gear mounting section from the fuselage - I did an off field dead stick and thought there was no problem --except for a hidden ditch bank--all fixed in an evening and back in action.
No big deal.

stomper

My Feedback: (20)

The gear is fiberglass/resin with CF rods.

bodywerks

My Feedback: (4)

It has EVERY mod that is out right now, including the carb.

bodywerks

My Feedback: (4)

Carb servo is a digital with about 80 ounces, but I will keep this in mind.

bodywerks

My Feedback: (4)

Coche,
My fuel line setup is the same as everyone elses. I have the vent line running around the back of the tank and then it goes forward and out of the bottom of the engine box. There are no cuts and the fuel filter is well sealed.

Flat spin.
Besides rechecking my throttle servo geometry, I think I may have to take the carb off and check the reeds as you stated.
For everyone, I fly mine at a very high idle once in the air, probably 2500+ RPM, so too low of an idle isn't the problem.

This problem seems too predictable to be something so secret, like fuel line routing or servo strength, etc. I am going to pop the carb off this week and let you know what I find.

BARCC

Yes!!, I hate it when people refer to fiberglass as Carbon Fiber or viceversa!! Pisses me off!!

flyingcrazy

My Feedback: (28)

I have seen some enignes that do not run good with a filter you might give it a try with out it ! Filter the fuel befour it goes in the tank .

going vert

My Feedback: (11)

After I called DA today it reminded me, yet again, that I will never fly another motor. New header is in the mail.... Not sure what the problem was. I'm sending the old one back for them to take a look at.

I was flying with a buddy this weekend that was flipping on his non-DA motor for ever. It never started. And this new motor replaced another brand that would not start either. There I am, three flips, pop, pop, pop, brum, brum.......

rmh

All of our non DA engines start first flip----
It ain't the engines -it is the starting technique.
If your buddy has changed brands -and still having trouble - someone has not helped him learn proper techniques .
A Walbro carb will not start from cold unless wet --and you can hear this little squishy sound on full choke - Once you hear that -and not before -- you simply set low idle -engage spark and typically either pull prop thru (feel for a bump) or - just flip smartly.
Some engines do, however run better than others in odd attitudes .
Our fifties can be flat spun ,bunted -low/high throttle ' knife edge either direction loops etc., and the engine never falters .
It is all in the setup-
There are far more bad engine techniques than bad engines.
as for servo strength to overcome spring on the DA50 carb --a 20 in ounce servo will handle it perfectly - test the pull with a tiny scale -how many pounds do you think it takes to open it?
We use same carbs on our 50's -- spring on/off no detectable difference.

Josey Wales

My Feedback: (61)

Im a first time gasser..DA-50...For the life of me I cant hear that "squishey" sound..I just choke until it starts then dies..usually about 10 flips when cold...

CHassan

My Feedback: (13)

Ok after carefull consideration I'm going to try adding up thrust to my engine. Thats one of the 2 things I can think of that would cause up trim while upright, up trim while inverted, up trim in knife edge, and down trim on landings and unpowered dives (not that I do powered dives).
I've talked with another Yak owner and it appears he has the same problem, and had to use, from what I hear, a good deal of up thrust. Has anyone else encountered this problem? I'm also thinking about adding just a tad more right thrust while I am at it.

going vert

My Feedback: (11)

We fly with lots of experienced gas fliers, that could not start these engines.

One of them, which is now used as a paper weight, would cut throttle 50% when inverted. Sent the motor back and the manufacturer could not fix it. We tried everything, new carb, ignition, prop, everything.....

I had one that was sent back. Manufacturer said it was a timing issue, but they never test ran it (after they had it for five weeks). It still took 40 - 50 flips to start (wet).

Anyway, this is not a DA thread. I am very happy with my DA motor and the customer service I get there (which is why I will never switch brands). And, the motors start on the 4th flip almost all the time, with no special engine technique. I'm not very patient (or smart for that matter), so easy engine starting is a must for me.

Back to the yak!

bodywerks

My Feedback: (4)

Thanks. Will go ahead and try that also, as I am out of ideas. I will just double filter it into the tank...

bodywerks

My Feedback: (4)

So, Dick, can you give me any pointers on my engine problem??? You are closer to my altitude, so you may ahve some other pointers?

rmh

OK basic setup
All fuel lines must fit tightly to all tubing - air leaks kill pumping
NO fill valves -No filters -no exceptions
Tank is best, if centered on carb -
With tank 1/2 full remove line from carb - allow fuel to drain back into tank
attach line --apply choke -open throttle - flip prop
fuel should advance with each flip .
This true for any Gasser .
I use a brass Weatherhead tee just prior to carb -with a fill line and plug for filling.


Ignition :
cushioned module - a std ,GOOD 4 cell battery (ask Dave Johnson if think you have a better idea ).

Next-- A 22x8 prop Mejzlic- a stock muffler and
32-1 Mobil Racing Two stroke.
Frankly -I find no need to go through a break in oil process and power levels simply gradually improve -providing you don't burn the engine trying to squeeze more revs than yer buddy's engine.
The DA's I have set up run perfectly on this with nary a scratch or carbon problem-BUT- Use what makes you happy.
With engine running at a nice idle -you should be able to CAREFULLY pick up the model and tilt nose up or slightly down with no notable difference in running .
Fer Chr--sake don't add power or try this with a larger plane!

If the setup does not pass this test - ST0P- find out why.
I won't say more till you are certain it passes all of this .
Personally I use a ZDZ50 - My choice -but your engine should be very similar in power and performance .
As should any 50 in good repair
The exhaust system can kill low speed and high speed performance.

Edge

Gee whiz goinverte my DA starts in one flip......