Ali

My Feedback: (5)

Hi Ian
Thanks for the photos of your L-39. Looks great.
I have asked the question of Anton but as far as I was aware there was not a hydro oil oleo system available for this model. I had the same problem with soft springs on my air world L39 and it took some messing around with different springs to get it right. I got there in the end with the help of a specialist spring supplier. I will wait and see how my SM one turns out and if I need to add springs I will update on what I do ( Unless anyone beats me to it which is quite possible as I am now heading overseas for events so wont have much time to build for a while )
I made the mistake of deciding to try and improve the look of the inside of the model by applying a coat of primer. Dont know why as it looked perfectly ok as it was. Now I have started I regret it as its taking loads of time to mask and paint areas without getting over spray everywhere... oh well!
I made the tanks up. These are super strong ( A little overkill in my opinion ) Kevlar units. I changed the fittings to BVM, as I prefer the larger ID tubing, the higher quality brass pipe and cap fitting, as well as the BVM ones are supplied with the little brass sleeves to solder over the pipes as retainers all pre cut. I also used BVM poly pipe for the clunk line as I find this is far more flexi than Tygon and does not go hard as it ages. Most important when making multi tank set ups. I see many air issues where the clunk gets caught up due to being too stiff which can end in a flame out.
Any one onto gear door cylinder fixing yet? The cylinders I have here seem a little short. I may take this opportunity to change them out. I could get round ti by moving the horn geometry on the door but I might take the easy option.
Warbirdracer! Great shots of your flight in the L-39. How was it? This is something I would really like to do.
Regards Al

WARBIRDRCER

My Feedback: (22)

Ali, The flight was great. We took a sunrise flight to 10,000', did some steep turns and a couple of aileron rolls, and then I was given control and allowed to cruse at 300 Knots, level turns, and do one each roll to the left and then the right. It was a dream to fly a jet like that after growing up outside of NAS Pensacola, Florida Navy Base. I will send more photos the next time I fly.

WARBIRDRCER

Ali

My Feedback: (5)

I am soooooo jelous!
As I expected. I just received conformation that SM do not offer the hydraulic damper version of thir U/C for the L-39. Sorry!
Regards Al

thinwing

hi warbirdrcer...your flight reminds me of flight in a l39 summer of 05/06....departed sac southbound 3 or 4 min later level @ one two thousand...aileron rolls enroute yosemite than down the back side of the sierra nevadas following canyons north of mammoth lakes into nevada.It was a ride I will never forget and logged about 1/2 hr sticktime including approach for landing......the gas bill was impressive too...I wrote a check to cover 500 bucks in jet a...k

ianober

My Feedback: (12)

Man, that's a bummer Ali, I could have sworn they had them. Well maybe Anton will plan them for the future but I didn't remember ours at Fresno having super soft springs. I guess it is mostly a matter of personal preference.

Dave Presta

My Feedback: (3)

FWIW, I flew the Skymaster L-39 at Fresno Jets and do not remember thinking it needed a spring change in the landing gear. It taxied, took off, landed, and tracked very well. I do recall some pilots having issues with the Airworld L-39, wing rocking quite a bit on the ground, but that is not the case with the Skymaster that I flew.
So if they do not have a system that can change the dampening, then I would venture to guess that the stock system is quite sufficient.
Dave

Jet Doctor

Hi Guys

The spring in the main gear is a real issue. I e-mailed Skymaster a while ago about this issue and Anton said there was no alternative oil filled units available yet. He did however ask me for my mailing address and 3 days later(no charge! - great service!) I received an upgraded set of springs which are much stiffer. My L39 was a real waltzing Matilda on the ground. The only problem with the new springs in is that the model is now negative on the ground. The only way I could get around this was to convert the nose leg to a Robart 110 deg leg and drop the nose leg 25 mm. Be careful here, even though the model looks negative on the ground, it might not be, you need to confirm with an incidence gauge.

Also remember not to pump the tyres too hard otherwise they will not fit into the wheel wells. A real pain to deflate them afterwards. An alternative here is to change the tyres for Dubro foam ones.

We have had 3 lost canopies on our L39's here. I would suggest that you put some carbon tape just below the ridge where the canopy frame mounts. It seems as if there is some flexing happening in the nose section during tight turns. Ali will need this!!! I think you guys that are going to be using cockpits will be cutting down this ridge to get the cockpits in anyway so I would definitely recommend this.

We are flying ours on Jetcat P120's and they have no problem rotating at around 80m with about 15mm of flap. After takeoff, you seldom need more that 50% power for scale flight.

Ian Burridge

Jet Doctor,
Anton sent me some new springs and I found them so strong there was only 10mm movement on the oleo! Mine was also very negative on the ground as well. In the end I went back to the soft ones as it was the lesser of two evils.

thinwing

Jetting...I assume the shorter closed coil spring on left is new spring....It looks totally compressed as is....k

Jet Doctor

Hi Jetting

You're right. The green one is the new one. As you say, maybe the lesser of the two evils is to stay with the softer ones. I played around a lot with different springs but all but that one were too soft. On a wide runway a little snaking is OK. Unfortunately our runway is very narrow so can't run around too much!

You can play around quite a bit by combining the two springs as well but the moment you start getting it hard enough, you end up negative on the ground[>:][]

The problem with the original spring is that they just about bottom out with full tanks.

Maybe theywill eventually get around to some oil filled ones that will have damping?

Ian Burridge

As you can see from photo with full tanks the oleos are fully compressed!
Ian.

thinwing

jetting I see what you mean....you would have to extend spring rate on nosewheel strut as well so as to avoid negative wing incidence on ground....k

WARBIRDRCER

My Feedback: (22)

DANGER DANGER!!! WARNING WARNING!!! CAUTION CAUTION!!!

I am posting an Airworthiness Directive, AD on SkyMaster L39 wings.

During the process of locating the wings to the fuselage I discovered the wing attach area were the cap screw attaches the wing to the fuselage was not glue during manufacturing. The only thing bonded to this structure is the wing roots thin fiberglass overlay. Please look at the photos for details of this AD.

WARBIRDRCER

My Feedback: (22)

Thanksgiving Weekend Update.

First, Happy Thanksgiving to all.

I have located my Landing Gear, Almost finished routing my air lines, Installed my Turbine Plumbing, and can almost smell Jet-A.
Any new ideas on the Landing Gear strut problem??

WARBIRDRCER

My Feedback: (22)

I did not want to forget my helper.

acrored

Hi WARBIRDRCER, take a look at this link, post #15, http://www.rcuniverse.com/forum/m_57...acrored/tm.htm , i hope this pictures can help you out, i built that one a long time ago, take care...

avicom

My Feedback: (14)

Hi, looks that too much turkey makes you forget to fix the DANGER, WARNING, CAUTION no glue wing join root ribs ,you just mention in a previous post and continue to install the LG. Don't forget to go back to your findings for a safe happy flying day.

Rgs,
Alex

WARBIRDRCER

My Feedback: (22)

Acrored,

Thanks for the link on the gear door installations. I was wondering about this myself.

Real good info for anyone working the gear door step.

WARBIRDRCER

My Feedback: (22)

Avicom,

I am not a turkey fan, so we fry chicken for thanksgiving the way my grandmother and mom did in the day. My post should have stated: I have located my landing gear, but was unable to install due to more required rework to this kit. I am going to go back and apply Hysol with gessets to the corners and upper skin panel, and then I will install my gear where I located them a couple of days ago.

Thanks,

WARBIRDRCER

CARS II

My Feedback: (7)

Thank you for the tip on the wing roots, I cheked my set and they do need some glue.

WARBIRDRCER

My Feedback: (22)

CARS II,

While you have the glue out, look in your main gear well fuselage center section structure.
I found my ply center section fuselage structure was not glued to the wing tube housing. This allows this structure to move left and right of center, and would cause gear door problems during in flight operations.

Keep me posted on any problems you see.

Thanks,

WARBIRDRCER

avicom

My Feedback: (14)

[sm=wink_smile.gif][sm=thumbup.gif]

WARBIRDRCER

My Feedback: (22)

CARS II, Pilot TW, Edger Perez, Ali, Schroedm, Slam Dunc, Fasteddi, Jetting, Thinwing, Jet Doctor, and GreenAcre:

Thanks for the time you have all put on this RCU link. It has made my project much more enjoyable and I have learned from all of you.
Please take the time to post some updated photos of your jets and be sure to give reports as you fly them.
I have listed some questions for all of you below.
I think I will make the end of year goal on the first flight for this jet.

Any other SkyMaster jets you would recommend for the P-120. I am already looking for my next project. I really like the F-16. I have friends flying the 1/8 and 1/6 scales. Has anyone you know operated either on the 120?
I will send some photos from the jets here in the Oklahoma City and Tulsa area.

CARS II,
How is your progress? Are you going to make the end of year first flight??

Pilot TW,
Thanks for the link you posted. Great gear door install examples. This guy is a pro.
http://www.rc-unionen.dk/nytforum/to...89&whichpage=1
I added it to this message for others to see.

Edger Perez,
How is your L-39 coming??

Ali,
How is your L-39 coming??, Any luck on the landing gear springs??

Schroedm,
How is your L-39 coming??

Slam Dunc,
What jet did you get first, and how is it coming??

Fasteddi,
How is the Eurosport coming??

Jetting,
How many flights on the L-39 to date??
How is the landings and ground handling with the compressed gear due to the weak springs??
I slotted my flap and aileron horn locations today, but my Hysol was bad. I will pick some up tomorrow and move on to installing as you did. Thanks for the help.

Thinwing,
How is your jet project?? Any ideas on the spring issue yet??

Jet Doctor,
Any luck on the landing gear springs??

GreenAcre,
How is your jet coming?

Edgar Perez

My Feedback: (13)

I'm currently programming my Fei Bao F-18F for an upcoming maiden(Got it on Jan 2007, so need to hurry up to avoid a two year time frame[X(]).

Already started a Global Jet Club T-45 Red Bull.

Once done on those, will start on the L-39

Yes, I'm a slow builder[:@]

Goo luck,
Edgar

PD: Think the F-16 1/6 can work on the P-120, but with limited vertical.

CARS II

My Feedback: (7)

Working 6 days a week and been away from home that long doesn't give me a chance to build that much but, I'm planing to get more time off in Dec. so I can get at least two projects finish by the years end ( L-39 and Patriot XL )