Jack, just came in from finishing up the changes to my air system connectors and read your post. Glad to hear you like the jet. My setup is very close to yours. I see you needed 3/4 pound of lead in the nose. Did you melt down lead and pour it in a mould of the nose? I'm also going to look into adding a gyro. Probably my biggest worry is tracking straight on takeoff!

Tomorrow I plan on pressurizing the air system and check for leaks. I'm also going to finish hooking up the ECU and other electrical work. I still need to do something about the bird's nest of air hoses, aileron and flap servo leads in the wheel wells. I've been scratching my head over how to organize this stuff so that nothing gets hung on a wheel. I've got the BVM wing root air connector kit, but it sure looks like it would be easy to get it slightly misaligned and end up with a source of air leaks.

Mark,

The looks of the plane are tricky. It looks pretty flat (even a little negative). But then I measured the wing incidence against the ground and was actually positive.
Besides adding the BVM upgrade, I did not touch anything on the gear.

On take off, it needs you to hold up elevator quite a bit to rotate. I might try taking off without flaps and see if it rotates easier. The other thing I might try is to reduce power on take off (sometimes too much power sinks the nose)

I'll report on the experiments next week.

By the way, I did 3 flights on the first day, so had time to actually enjoy it

Jack

as for my balance, I stuffed all three batteries in the nose, 2 six volts packs 2500 mah each and one Venom brand nimh 3500 for the ECU. and all I had to add was an old stock ecu Jetcat battery also in the nose compartment.


Mark

Jack,

What type of gyro did you use? When I 'Google' GR 370 I don't get anything about airplane parts.

Thanks,
Randy

I found some fishing weights that fitted as if they were custom made for the plane. One is a 1/2 pound sphere and the other 2 are 1/8 pound bullet shaped weights. I put them together, wrapped them in bubble wrap and masking tape and velcroed them in the nose as far forward as possible.

I did't do the ez connectors for the air. I'm afraid they can leak if the wing moves. Since the wing has only one spar, it has a slight forward and back play that I think could disconnect the EZ air (I saw Jeff's L39 go through this and ended up belly landing, not pretty).

I'll try to post a picture on how I did my aileron wires. They are very far from the wheels. What I did is have the extensions in the fuse come through the lower hole in the rear former. Then I just connect and push them back again. No wires left in the wheel well.

And regarding the Gyro, I always use a Gyro on the nose wheel. To me, take off roll is the most dangerous and vulnerable part of the whole flight. Plus, a gyro on the rudder is always helpful

hurry up and fly your plane, you will not regret it!

Jack

Jack, mine is powered with a P-80 and was very suprised on the speed and the verticle it had, not unlimited verticle, but I was happy with it.

as for my first take off. I powered up and it ran, and ran, and ran down the runway. about 600 feet. I told larry my spotter, that I was powering off and gonna taxi back. keep in mind I had zero flaps on take off, since I was on an asphalt runway 2500 feet long, I thought I did not need them. So as soon as I powered off, it lifted and jumped right up. so quick thinking I powered up to full power.

As it was spooling back up, the L-39 started sinking with the nose up, but very stable, no sign of a stall or falling off to either wing. I quickly raised the gear and proceeded to climb out. I did have a liitle negative nose attitude and about 6 ounces to much nose weight.

Two clicks of up and it flew great, only issue I had during flight was, I use dual rate and zero expo, so low rates was not enough and high rates was a bit too much. I just got an e-mail from a friend inviting me to their site where others also have L-39's and I hope to get a few more flights on mine......


Mark

I meant JR...

That is what I was mentioning about how too much power can actually sink the nose. Probably as you throttled back, the nose strut decompressed, giving it a positive angle of attack. Did you have the strut upgrade on the first take off?

I guess it must be very similar to mine, because all my bats are lipos (including ECU)

yes I did the strut upgrade on first flight, but it had very noticable negative nose attitude. I did correct that, but have not had a chance to fly yet.


Mark

Make sure your nose gear retracts. Mine touches slightly on the front of the wheel well, so if I extended the nose strut by even an 1/8" it would not go in.

Actually, maybe that is a good indication... My strut was as long as feasible. If yours had any extra space, then it was too short (i think, just guessing here)

as for gyros, all my bigger jets have them, Boomer xl, SM L-39, and the SM Hawk, but the two Facets I have, 2300 and the new 1700RG do not.

At liberty Bell Jet Rally, I had my gyro go on me on take off, as I rolled out on down the runway, I powered up, and just before rotation, the gyro sent the boomer into a very hard right turn and into the corn stalks. minor damage to both wings and the nose, but fixed and flew yesterday.

Thanks for the info Jack. You echoed exactly my concerns about the EZ Air, so I'll abandon that idea. Can you give me the make/model of your gyro? I agree about the takeoff roll being a high-risk phase. If a gyro will help keep it tracking straigt, then I'm all for it. Any pics of your wheel wells showing the routing of air lines and servo wires will be most appreciated!

There's definitely light at the end of the tunnel now on my build. Initially I'd built it exactly per the BVM Supplemental Instructions, and it was incredibly tail heavy. BVM has the ECU, air multivalve, fuel pump, filter, UAT, etc all in the engine bay. Man, that was a lot of weight aft. I got demotivated knowing I was going to have to basically start over and move everything except for the turbine up front under the canopy and windshield. Then, it seemed like it was one step forward, two steps back. I got demotivated. But, I got back into it a few weeks ago and now I'm close to the finish line...got my "building momentum" back!

OK, got it...thx

I tried to keep my P-80 all the way up into the air inlet, but the tail pipe was too short.

what did you guys do? order a new pipe when you moved your turbines far forward?

all I did was add to the mounting rails for the nose gear, I used two 1/4 square hardwood pieces and hysoled them to the rails, that lowered the gear just enough , I hope, and had plenty of room to clear the opening......

do you guys use gear doors? I did, and look realy nice when they operate...........

I left the stock pipe, with the lower edge of the exhaust slight outside the rear of the fuselage. Then, placed the turbine with the recommended gap between the exhaust and the bellmouth. (I think is like 3/4", but don't remember. I can measure it if you want)

Yeap, full gear doors. All preinstalled with the ARF PLUS PRO. And they worked as they came, no issues. I had one cylinder leak (was sitting there for almost 9 months), but some oil and oring lube brought it back to life. Still, Jeff offered to replace it under guarantee just to make sure

Here are some pictures.. hope they help

#1 Air lines detail
#2 Servo leads detail
#3 Wheel closed, you can see there is plenty of space
#4 Turbine install. Nothing in the turbine area, just the turbine itself
#5 Install under the cockpit. Solenoids and regulators are underneath the board
#6 Install under the front cockpit: breaks tank, Fuel pump and UAT (balanced it with the UAT full). Gear and door air tanks are on top of fuel tanks (different from Skymasters instructions
#7 Canopy frame tabs. one on each side
#8 Ugliest shop ever.... but hey... at least I don't need to build in my living room!!!


Jack

Glad everyones L39's are doing well, repairing mine at the moment [&o] nothing too bad just replacing the retract bearers and a little respray. I love my 39, one of the easiest jets I've flown.

Never had a problem with the EZ airs, I've lost count of the number of models I've installed them in and never had any negative feedback from customers. Also put them in the L39 without issue but I'll admit that if you get the install wrong they can be a pain.

I was thinking of trying a cheetah in this but think that's going to go in my F5, I think the new 100SX will be perfect for this jet so I'll give that a go when I get it. The 120SX was a bit much for IMO.


Cheers, Alex

Jack, thanks for the pics! I appreciate the help. Oh, I think your shop looks just fine. I'm building mine in the garage, which in Florida, in the summer, is a test of endurance. One question: I don't know squat about gyros for RC planes. Is the 370 strong enough for jets? Would the 770 be ok?

Alex, I like the idea of the EZ Airs for sure, but I've never installed them before, and I'm reluctant to experiment on my L-39. This is something where I wish I had someone nearby that could help. I've been pretty much going at this build alone, with help from folks here at RCU. BVM Tech Suppport used to help, but my last two emails to them have gone unanswered. I don't even see the L-39 offered in the "Skymaster" section of the BVM website, so perhaps they've stopped selling and supporting this model.

I'll try and get some pics of my build today.

as for the L-39 on BVM's site , it is there, they moved it to the Xtreme jet listing.

and when on BVM's site, look at their event photo's. Liberty Bell jet Rally 2010, there in the front middle, you can see my L-39 in the group of BVM and Skymaster jets.

Hi,
I have the Flyeagle l39 and I have the same problem with the main gear ie springs to soft. Can you please tell me which BVM uprated springs you are using?
Thanks
Alex

Ok, good. Now that just leaves the question of why BVM's Tech Support folks are giving me the silent treatment. They used to respond fairly quickly and were very helpful...now, nothing, zip, zilch, nada

Ok, here's some pics. I tried to do the layout with an engine bay, a forward 'wet' bay and 'dry' bay.

The engine bay has been cleaned out from the BVM setup. The upper right panel now has the shutoff valves for the kero-start and fuel lines. The in-line Festo filter zip-tied above and behind this panel is in the overboard vent line. I got to thinking, and I'd hate to get dirt/dust back-filled into the fuel system from the vent line. Being clear and easily accessible, I'll be able to keep and eye on it.

I fuel-proofed the wood floor panels and UAT cradle. The air tanks, 2 for the gear and 1 for the brakes, are located under the 'wet' bay floorboard. The design is 'modular', by that I mean that the floor accessory boards can be isolated and removed without having to disassemble other components. When I did this complete overhaul of the innards, I tried to do it with making future maintenance access as easy as possible.

I still need to tidy up the air and servo lines in the wheel wells, locate two more satellite RX's and the ECU lipo. Then, other than tweaking things like control throws and flap rigging, I need to see where my CG is and how much weight I need in the nose.