A flying buddy is getting ready to test fly his newly finished WING MFG P-38. Any of you guys out there build and fly this airplane??

Any suggestions on CG? How about control throws (high and low rates)?

Any constructive advice is greatly appreciated!!!!!!!!

Use high rates, definately. Better yet, dual rates. I lost mine because of some bad advice to that effect. Mine was heavy at about 13lbs. Glassed with one layer of resin and very thin spackling to fill the weave. Painted with Coverite spray. I used 2 TT.45's, plenty of power. We diagnosed my problem to setup on the gear and not enough throw on the elevator. I set the gear up so the plane sat level on the table. As it ran down the runway I noticed that the nose was a little down like it was plowing. This created a positive pressure on the wing top side along with insuficient elev throw and it was obvious I wasnt gonna get off the ground. Speed was not an issue. I throttled back too late and ran off the end of the runway which at first I didnt worry about. Turns out, I found a rock pile under the grass. Took out the entire fuse pod and bent the main gear struts. No other damage. If I were to build another, I would use 1/16" ply laminated to 1/8" balsa for the fuse pod instead of 3/16" balsa sheet. That and some triangle stock on the nose gear mount. When it busted loose, it took out everything in the fuse pod back to the leading edge of the wing. I also used 10 std servos, too heavy. That short cut was a big mistake. HS81's would work for the elevator and rudders. 2 on elevator and 2 on rudder. I sold the plane as is and will build a bigger one to lighten the wing loading some. Somebody else will have to tell you how it flys. Bummed! Oh well, NEXT PLANE!
Edwin

Built one several years ago with 2 Magnum 40XL's. Weighed about 11lbs, finished with coverite film, then weathered, and clear coated with Black Barons. Flew perfect with the balance and throws shown on the plans. Definatley needs seperate servos for each rudder and one for the nose wheel. Also one on each engine, & each aileron. The flex cables will drive you crazy trying to get all the slop out. I did not have flaps, but seemed to be OK without them. I used Rhom-air retracts that were junk. Really wish I had used Spring-airs.
Low fast passes with a victory roll at the end of the runway will give you chills.
I lost an engine at lift-off, (I think) & it snapped into the dirt. Maybe I will rebuild it someday, since all the palstic and glass cowls survived. I have the plans and all I need is a set of wing cores.

Finishing up a Wing mfg. P-38 with Spring air retracts in the next few days. Do I balance with the retracts up or down? Also, if you can explain why up or down it would be appreciated.

Thanks Bill

Balance with gear retracted. The gear will move the CG back when they swing to the rear. You will be little nose heavy when they are down, but that is better than being a little tail heavy when they retract. The change will be very small, and may not really effect the flight characteristics though. There is also a theory, that since the gear are still mounted at forward position, that weight does not move back when retracted. I dont know for sure.
I did find on mine, that once the gear had been retracted, I needed to add a little down trim, but I believe that was due to drag, and not a CG shift. The aircraft is a good flyer, so if you balance conservetivly, you will be OK.
I received an e-mail from the guy with plane this thread was started about, and said he flew his on Sunday with no problems. Said seemed a bit noseheavy, due to 2 12oz tanks full of fuel. That is a lot fuel, so a long flight can change the CG by a large amount.

Thanks TLH101, will do. Here is some pictures, minus cowls...

I can add little to the above, except that ALWAYS do the vertical test. As posted above, do not lose and engine.
I did not see what engines you have with those three blade props. Unless the engines are .60's, I would suggest the first flight with two blade props for more efficiency. Make the take off run as long as possible, so that you have maximum air flow over the control surfaces at lift off. Plan on making the plane take off. Most do not automatically take off, but must be made to rotate.
This plane has very heavy wing loading, so make sure your use the rudders for turns and expect to use the elevator to tighten the turns.
Good Luck,
Twinman

The science of weights and levers (and my empiric testing) shows that retracting the gear on a 38 does move the CG back. Also, every 38 kit I've had recommends testing CG with the wheels up.

Counterpoint to that is that I can't tell the difference in handling between gear-up and gear-down.

Fortunately, when it really matters: low fuel, low thrust, low speed, no room for error (landing!) the gear are almost always down, hence CG forward.

mt

I AM THE "BUDDY" RAMFLYER WAS TAKKING ABOUT. I NOW HAVE 12 FLIGHTS ON MY BIRD. WHAT A SWEETHEART! WHAT THE GUYS ARE SAYING RE THE ROTATION IS RIGHT. I HAVE BEEN LOOKING AT A LOT OF REAL PHOTOS AND IF YOU LOOK CAREFULLY, YOU'LL SEE THE PLANS HAVE THE GEAR IN SCALE POSITION BUT NOT PROPERLY POSITIONED. WHAT I MEAN IS, ON A REAL 38 THE MAINS ARE ANGLED FORWARD. THE PLANS HAVE THEM STRAIGHT DOWN. I HAVE SINCE ANGLED MINE FORWARD AND I EXPECT A LOT EASIER ROTATION. MY BIRD IS 10.5 LBS, NO RETRACTS BUT I DO HAVE 24 OZ TOTAL FUEL ON BOARD AND I HAVE FOUND THAT IT LANDS LIKE A PATTERN PLANE. DONE LOTS OF TOUCH AND GOES. SET UP A CONSTAT RATE DECENT KEEPING A LITTLE POWER, JUST A LITTLE IN , OR SHE WILL SETTLE REAL FAST AND YOU'LL RUN OUT OF ELEVATOR EVEN W/ DUAL RATES. I USUALLY CARRY ABOUT 1,2 CLICKS ABOVE A LOW IDLE. PAY ATTENTION TO HOW THE PLANE TURNS. THIS IS A GOOD INDICATION AS TO THE HEALTH OF THE ENGINES. IF IT GETS HARD IN A DIRECTION, THROTTLE TO HALF, LET THEM RICHEN UP AND THEN THROTTLE BACK UP. YES RUDDER, JUST A TICKLE, IS GOOD. DON'T HOLD IT! ALSO, I HAVE A TAKE APART FUEL FILTER, MACHINED ALUMINUM, IN THE MUFFLER PRESSURE LINE. OPEN THIS UP AND PLACE A SMALL STEEL BALL FROM THE HAND PUMP OF A LIQUID SOAP DISPENSER IN THE DIRECTION THAT WILL HOLD PRESSURE IN THE TANK. THIS REALLY KEEPS THEM RUNNING SMOOTHLY. TRY IT. YOU DON'T WANT A REAL TIGHT SEAL. SOME LEAKAGE MUST OCCUR OR IT WILL OVER-PRESSURE. LET ME KNOW HOW IT GOES. WORKS LIKE A CHARM ON THIS SHIP AND OTHERS. I HAVE A FUNFLY NOT FOR SALE THAT WOULD DIE AFTER ABOUT 30 SPIN TURNS. THE CHECK VALVE STOPPED THAT. P-38BOB