Well, to make the story short I was again requested to maiden a friend´s airplane... this time a Skymaster L-39. One of the things that I like most from sites like RCU is reading threads like I would try to write (sorry for my English) so I hope that you guys enjoy it too.


This L-39 was planned to be flown without the interior cockpit, and the installation was done partially over the wooden floor. As soon the cockpit arrives it will be re-arranjed to fit. The building was done again by Mr.Patake and it was very quick. The plane has a outstanding rivet and panel detailing, very close to scale and well done... the rivets look of the right size, as well the inspection panels, air scoops etc.The paint was also well done and the landing gear, specially built for this plane looks very scale. This plane weights 12 Kg and it is powered with a Jetcat P-120. The radio is a old 9CAP with a PCM receiver, single 5 cell 2800 Mah battery with a heavy duty switch, and 3050 Futaba digitals on every flying surface.

The main problem that surfaced when the plane was ready to fly was his nose down attitude while sitting on its wheels. The tail was sitting up too high.. looked more like a top fuel funny car instead like a airplane! the solution was removing the original springs and substitute it for a stronger and shorter spring wich starts to be compressed when the suspension is at about 75% of its travel, and a small piece of silicone tube that just extend the legs when they are unloaded and ready to retract. We also made a 1cm thick plywood base for the nose gear retract just to raise a little more the nose, and then we finally got the fuselage paralel to the ground.

After doing a inspection at Mr.Patakes home running the turbine at night for a short period, trying to spare the neighborhood as well as we could, we checked the flying surfaces throws and CG as recommended by Mr. Anton. We also checked for bubbles in the header tank and radio link range . So runned out of excuses, we went to the club next day at noon ... the problem was that the wind was gusty and at 90 degrees.. I hate when this happens , but a promise is a promise, so I wasn´t able to chicken out the test flight.

Well, again we checked everything and after fueling the plane , cycling the landing gear and taking a deep breath I flipped the switch , starting the led sequence and advanced the throttle .. as usual the P-120 started to life, then we closed the turbine hatch and canopy and taxied to the heading... the ground handling of the plane was good even in the strong wind.

Having a trailing edge nose gear I expected a good takeoff run, even in a crosswind.. The plane performed as expected, and it went straight as a arrow... however it showed a slight tendency to "dive" the nose as the speed was increasing on ground.. I started to compensate with "up" elevator and it rotated after 100 meters of run.. the rotation was not super smooth but it was not bad... then I needed to add 2 clicks of elevator and aleiron and the plane was flying well.

The plane was very good, it flies pretty much like the Savex L-39 but with a huge advantage on the visibility due to its size.. it also is very stable and the CG seems right at the factory setting... however I didn´t followed the instructions and didn´t dialed the 30% expo recommended in the elevator. I used 15% and the plane was slightly pitch sensitive around neutral.. however the plane was flying good enough to handle it to my friend to enjoy it a little while. After 1 or 2 minutes (about 4 from takeoff) I got the radio back to prepare to land the beast..already a bit nervous about the crosswind.

After bleeding some speed with the turbine running at about 40% trottle I flipped the gear switch and then the flaps.. almost no pitch trim happened and then advanced the stick to 50% to make a inspection pass.. and then things started to worry me. Just one wheel lowered !! then I cicled the gear again and It didn´t move anymore.. I has only one main gear wheel stuck down, without able to do a belly landing on the grass... After discussing the situation with the owner, (LOL) we decided not to land it on the grass, instead on the strip. Then I proceeded as it was a normal landing, trying to touch down it as smooth as I could avoiding wing damage. The procedure was as usual, a rectangular approach at about 40% of power reducing the throttle as needed to keep a nice descent rate without fiddling too much with the elevator.. then when the plane was about 30 meters before the runway heading the throttle was chopped down and flared it as well as I could.

The plane responded very well in this conditions. It didn´t dropped a wing or wobbled. It was very firm and it landed on it´s single wheel without bouncing. It runned a little on it and then the wing and nose started to drop, making a sickening noise on the strip of fiberglass
being sanded... the single wheel brake was also not working and the plane used about 100m of the strip when it stopped in the lawn.

However the noise, the damage was minimal, and the culprit was a defective air valve at the wing root. The air pressure went to zero when it failed and thus made impossible lower the gear..

this is a pic taken right after the landing .. the wing tip tank has a big hole and there is a small scratch.. seems that in this circunstances we decided the right thing to do..

IMO this plane is a good one.. it flies very well, it could be powered with any turbine in the 20 to 30 lbs class, it is nice with very good scale details and could be put around with minimun effort and work... if I have any critic to do is around the finishing of the wing landing gear blocks.. (they are really ugly and are not compatible with the good average level of the finishing of the plane)..other than that, this plane
looks and flies like the best and more expensive ones.


I should congratulate Mr. Anton for his creation as well Mr.Patake for its work.. as well my friend who is now a happy owner of a slightly
scratched plane!



Enrique

and finally here it is something that I really liked of this L-39: the rivets and raised panels!

Enrique; good report on the maiden. Seems like an easy fix to get it back to shape...

Ditto.. on the report, detail is always good.. and what a great idea for the impound area, our field here in Denver would sure benefit from the chain-link protection. A safe house with full view, so simple an idea but your field is the first I've very seen.
Lee H. DeMary
AMA 36099

Congratulations Enrique, glad the maiden went well. I am going to maiden one in a couple of hours...[X(] I will let you know how it goes...

Michel

Thx Ehab, the fix will be easy and I was very happy in keep the damage as low as possible on this plane.


Lee, the "safety cage" is a old suggestion of mine and some friends to the club members and only after they watched the video of the unfortunate accident in Hungary they agreed to invest the money on doing it... it uses galvanized steel tubes and a tennis court net. We estimate that it will resist a direct hit from most airplanes, and even if it doesn´t it will absorb some of it kinetic energy... Hope that most clubs around start to adopt safety solutions like this or better so we can enjoy our hobby around without ever reading again bad news!

Michel, good luck in the maiden! you will enjoy this one too.


Enrique

Good save! Precise decision to land her on the strip.

Got to retract the remaining gears if you are going for grass..

AL

Very good Enrique..

Just 2 minor scratches. Very good report also. I can learn a lot with these reports because I am building my first...

Nuno

Thx Nuno, Michel also posted in RCU a video that shows how well this plane flies, I am sure that you will enjoy it too.


Saudaçoes, Enrique

Hi from Curitiba!

Could anyone help me to find Mr. Patake in Curitiba?

I am a Danish guy who lives here permanent and I make TV dokumentaries. I would like to talk to Mr.Patake!

Kindly regards
Arne Rasmussen

Enrique....No need to be sorry for your english as it is fine to me!!![sm=thumbs_up.gif]...Thanks for the well written and detailed report....I enjoyed the read!!!......

Kevin

Thanks Kevin for the kind words... this L-39 maiden was a memorable one!

Mr. Rasmussen: I just sent a personal mail with Mr.Patake contact info.. also here is our club location, so you can visit us.

http://maps.google.com/maps?f=q&sour...h&z=18&iwloc=A

Enrique
Great Save & IMO a Well Written Report

Semper Fi
Joe

Thanks U.Joe.. I will probably write some new reports this year. Some really nice stuff is getting ready to fly here!

Congrats on your maiden though and sorry to hear about your gear up landing. At least it's easily repaired.

Your model looks great but I hate to be the bearer of bad news, but your wheels are facing the wrong direction. The struts should be on the OUTSIDE of the wheel. The nicely detailed wheel goes toward the inside of the plane. I almost ripped out my MLG blocks and notified the MFG of a serious design flaw because my gear did not fit in the fuse properly. Then I was set straight!


Les

Ama234 you are darn right. I did not notice that detail, even having one L-39.


Hector

Les, you are 100% correct and thanks for your observation. We wrongly installed the wheels this way because we didn´t used the fuselage gear doors, so they fitted. I´ll send a link of this thread to our builder, Mr.Patake for making the correction. (BTW, I also didn´t noticed it to this date)

Enrique,

all I had to do on mine was use the strut from the other side and it fit perfectly. It was a simple solution to what I thought was going to be a nightmare! [X(] LOL
Hope you're enjoying your L39. I can't wait till mine is ready to fly...they are such a neat looking airframe.

Les

Absolutely, you will love it. It is a very honest flying machine and easy on the eyes due to its size.. also good luck in the maiden!


Enrique