rdavit

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Flew absolutely fabulous! Very scale in performance with:

Inverted Saito-72's, Graupner 12-8 Props, JMH on board glows, GYA 350 gyro for rudder (Thank you Twinman for your advice in this forum on Gyro's)

Great looking kit, flew beyond expectations!

Few "heads up" thoughts/ideas:

1. Fixed landing gear blew out on VERY soft landing (grass....and I was not at the controls.....otherwise I would blame on my own pilot error.....flown by club expert who brought in extremely smoothy). Plans call for mounts to be glued in .....which I did.......definately need to be bolted together vs. epoxied.

2. Use a drill jig for the 1.5mm drilled wing screw holes. I found that if off center (hole in aluminum tube), wings will have 1/16"+ gap.

3. After blowing out gear....don't remove wing until pressue is off gear (plane is in craddle). Why? Beacause the tail boom will twist off at the horizontal stab...where the boom is the thinnest....and weakest. Guess how I figured this out (as I search for my digital camera to show the broken 1/2 tail assembly in my hand).

Having Fun! Good luck with your VQ.

Neophyte P-38 wanta-be.....Bob

f2racer

Do you have some pictures of your finished bird?

twinman

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When you say "Take the wings off" are you talking about ,unbolting the center section from the booms?
Removing the wings from the center section, should not stress the rear booms.
Congratulations....wait until YOU fly it...plan on having sympathy for students........shaking is normal!!!!
Looks neat doesn't it!!!!!!!
Glad you liked the insurance of the gyro!!!!

rdavit

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Twinman

Yes, it happened when I unbolted the center section from the tail booms. The landing gear had come loose (epoxy did not hold.....i.e. I should of bolted them in vs. what the plans say to do for fixed gear) and hung out at a 45 from the tail booms. When I lifted the center section, the torsional force (moment force) created by the engine weight/gear off at a 45 deg angle twisted the tail boom at its weekest point......tail section of boom.

Upon inspection, very little hardwood in tail to tail boom section. Most of support comes from balsa skin/balsa ribs. Excellent design for low weight; poor design for sillys like me who do not use cradles.

With some epoxy, formers, fiberglass.....and lots of TLC.....I'll have this beaut up in no time.

Bob

roadtrip

Does anyone have a pic of what a wing cradle for this P-38 looks like? I'm concerned about taking the wing tips off and on every time I go to fly and would very much like to build a wing cradle for transportation and glue the wings together, so I don't have to worry about all of the linkage hassle at the field. (not a lot of carpenter experience, here, so please bear with me.)

twinman

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Here is the holder I built for larger, 100" and 108" P-38's and will build smaller one for the VQ. Build it from PVC and put plastic pipe insulation over the top bars to protect the plane.
I suppose the wings could be stored with this if additional holders added.
Good Luck,

twinman

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Here is another view.

roadtrip

rdavit,
What servo arrangement did you use?

rdavit

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Roadtrip

I used 3001 Futaba servo's with a PCM receiver. The elevator required a servo reverser (if on a 6 channel radio or less) to operate both servo's, but found all servos to be more than enough torque/spped (even the rudder with a gyro....no tail wag at 75% gain......futaba GYA 350).

Bob

Having fun......twins now are a must! (plus, I can equate in cost without issue to what my wife spends on her "hobby": shopping......)

RangerVorian

rdavit

Have you fixed your plane and flown again???

rdavit

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Numbnuts666


Still fixing the tail boom (had to trim balsa up to next former due to jagged break....about 5 1/4" from tail former). Hollowed out and formed a replacement boom piece with a 4" square/ 6" long balsa block and glued in place. Next step is to plank with balsa about 2 " up on tail boom and strips down to rudder and stab.....didn't see an easier way to get strength back into the tail boom.....so......neophyte Bob in action: (epoxy + wood)^3 power always does the trick.

And I upgraded the engines to Saito-100's......should be ready for the weekend.

Bob

"you can fly without motors, but not without knowlege and skill"....Wilbur Wright

and all I have is motors......should be an interesting weekend.

RangerVorian

rdavit,

How did your plane balance with the Saito 72s and how is it with the 100s??? I have a pair of 100s ready to go for mine. Did it fly good with the 72s or does this plane really need 100s???

Thanks

roadtrip

rdavit
Are all of your servos 3001's? What about the engines and flaps? I'm going to use two Futaba 351's, as they are for single axis each, two servos.

rdavit

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Numbnuts666,

The Saito-72's gave the plane a scale look and feel. The Saito-100's is purely for a safety margin (i.e. tip stall on landing, poor piloting skills....this pertains to me, engine out,etc.). The CG with the 72's was off by about 2" to the rear (6.5").....pulled the batteries forward and placed up in nose of gondola (two 4.8 1650 mah), came in at about 4.5" or 115mm.

Roadtrip,

The 3001 servos worked fine for all (even a binding flap....it deployed without issue). The GYA 351 gyro is same as 350 except for dual output and input (non-y corded servo's). Twinman is an excellent resource for any twin issue and has written extensively on gyro's in this forum (I am still a neophyte on gyro's).

Bob

rdavit

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Numbnuts666

Well, I fixed her up (used fiberglass on tail boom....2 layers) and put the fixed gear back in with bolts vs. epoxy.....Added Saito 100's.....and she screams with power! (Had to hold tail booms on ground run-up....thought the stab was gonna split in two!)

Flew well after adjusting CG back to about 4.75" (moved batteries into gondola bottom... below wing) to counter the additional engine weight. And as a "new" twin guy, really saw the affect of a 1000 RPM difference in-flight (at about 4500-5500RPM)....boy does she yaw at mid-throttle if not synched.....thought we canned an engine....would hate to see if one went out at that speed/RPM. Therefore, reset each engine with end-point stops and decided to use a throttle/needle mix (5 points) vs. a pure linear mix...too much trouble (and I had this set up with a Y-harness before I upgraded to 9CAP radio).

Learning alot about twins and enjoying every step of the way. This forum has really helped and I appreciate the support. Twinman should charge by the hour.....or at least sell trademarked shirts "TWINS MAKE YOU CRAZY"......I'd buy if sellin!

Bob

William Robison

My Feedback: (3)

rdavit:

Always pleased to welcome a new pervert. Excuse me, I mean CONvert.

Haw.

Glad you're having fun.

Tendered for your consideration: The twin engine sync system from EMS/Jomar. Twinman doesn't like them, but I do.

Bill.

RangerVorian

I'll be using a 13 point curve thanks to my 9Z

twinman

My Feedback: (2)

I use the five point curve on my 9c. Ok so it does not have the 13 point curve. Quit bragging!! Be sure to make one of the rotary dials of one engine for the final "Tweak" at idle adjustment.
Good Luck,
Twinman
PS The job that pay for this hobby is sure getting in the way of enjoying it!!!! I am so pittiful that my son is building the VQ for poor old dad!!! What else are kids for!!!

RangerVorian

If it weren't for my D@MN job, my plane would be flying by now.



Oh well... gotta pay the bills somehow.

rdavit

My Feedback: (2)

Bill,

I purchased an electronic synch from EMS/Jomar and have yet to install it. How do you like? Magnets stay in backplate at 9000+ RPM? (Press fit or glue?) Did you use a heat sink on the hall sensor when soldering? I have 3 magnets per backplate...recommended 2...but with 4 stroke thought an extra magnet would help at low RPM. Drill and ream backplate yourself (Bolt Pattern) or send out?

Thank you


Bob

William Robison

My Feedback: (3)

Bob:

The EMS/Jomar sync controller works fine, within its limitations.

When I installed the first one I tossed the Du-Bro spinners (really, I kept them) and bought Tru-Turn. Didn't even give any thought to using the plastic backplates to mount the magnets. And I spent the money for TT because I wanted the best spinners and thickest backplates.

You can order Tru-Turn with any special machine work you want, including holes for press fit magnets and reverse rotating three blade props. They will charge you for it, and the work is excellent.

But there's no reason you can't do the magnet holes, or use a less expensive spinner, just be sure to have a non magnetic metal backplate. And balance it when you're finished mounting the magnets.

Yes, you want a slight press fit. Do be careful, if they fit too tightly you'll shatter the magnet when you try to push it in. Also, mix a little JB Weld or similar for added security; smear it on the magnet as you push it in, it also acts somewhat as a press lubricant. Then smooth a little around on the inside. Be sure you have the red side of the magnet to the rear.

All my twins are two stroke, with RPM going up around 15K-16K I've not had any problem with a magnet coming loose.

I have used three magnets per engine from the start, seems to make the system respond faster.

I mentioned limitations. The EMS/Jomar unit is not a true synchronizer, raising one throttle and lowering the other, it is just a follower type unit. Your throttle signal goes to one engine, the EMS/Jomar senses that engine's speed and makes the other match it.

They recommend using the weaker of your engine pair as the master, I say use the one with faster throttle response as the slave. Doing that, and using three magnets per engine, you get the least lag in matching RPM on the two engines.

And no, I didn't use a heat sink when I soldered the wires to the Hall sensors.

Hope this helps.

Bill.

f2racer

I was just browsing around on the Morris Hobbies website and came across this:



They guys who did this claim that it only added only 12 oz of weight for the plating! Looks amazing though.

roadtrip

I wonder where the cockpit in the Morris Hobby's web site Warbirds image gallery, 5th row down came from.

RangerVorian

rdavit,

What are you doing for transport??? Are you keeping the whole wing together or do you remove the wing tips??? My concern is the linkage for the outboard flaps that hide under the wing shield. samparfitt did a nice write up of how he cut a hatch into the shield but I'm not too sure if I want to do that. I'm very interested to know what you've done.

Thanks!!!

rdavit

My Feedback: (2)

Hi Mike

I found using a pair of hemostats on the ball joints makes for an easy connection. I place the plane on a PVC stand ($12 in parts from home depot) and remove the access panel with a cordless screw driver and snap the joints together with a 45 deg. hemostat plier. The whole process takes about 10 minutes to put the wings on and connect the flaps.


Any problems with the aluminum rod connecting points?

I replaced 4 of the 6 balsa mounts with hardwood (3 of the 4 loosened up upon removal of wingtip........tight slip fit once screws went into both tubes and raised aluminum around inner tube hole).......also found sanding mating surfaces on wingtips took alot of the play out (bent the center tube on a "boring" flight ).

Flew this weekend into 8-15mph winds.......landed without flaps.... can't wait to get back out to the field!

P.S. Are you finding the stall characteristics to be "add some power" or "oh sh*t"........This plane....at correct CG of 4.75" seems to fall out of the sky.....my experience so far.

Having more fun than what should be legally allowable!


Bob