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Old Mar 21, 2012, 09:42 PM
Balsa and Foam can Coexist
WAGliderGuy's Avatar
United States, WA, Seattle
Joined Feb 2010
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Build Log
Tritle Douglas DC-6B (F) in Everts Air Cargo

My Tritle C180 flies so I have decided to start a spring/summer project. I want to try something I have never done before so I am going with a multi engine plane, more specifically Pat Tritle's DC-6B. Should stir up some attentin at the field

I admit that I have never flown a twin before, yet alone a quad so this should be interesting! I am going to go with N151's converted freighter (not the -6A!) colors from Everts Air Cargo out of Anchorage, AK - she is still flying for them today and has been in service since 1958.

I was planning to enter into Funbuild 5 but my goal is early July for my club's scale fly-inn and I tend to drag things as long as possible





Anyways, I have finished the wing frame so far and just started the flap modifcation and the motor nacelles. It has been mostly smooth sailing since the long brown package arrived at my door. The only issue has been the miss-alinged aileron spar/wing tip on the plans but I already knew about that from reading other threads.

I will be modifying the wing for flaps and electric retracts. I want to give a shout out to 'payne9999' for answering all my questions about modifying and building this kit! He is also currently building an 80'' enlarged plans version.

I am going to be using HeadsUpRC's Power-Up 250 plus motors, HURC 10A ESCs, CC 10A UBEC (more then needed but better then the 3A I accidently ordered), GWS 6030X3 props (counter-rotating), E-Fflite 10-15 size electric retracts, TP 9Gs servos for the flaps and HS-55s for the tail and aileron along with the Spektrum radio gear.

Planning on using a mix of Parklite and Microlite with the graphics from Callie.

Oh boy here we go

Ethan

More pictures of N151: http://www.airliners.net/search/phot....net%252F&ref=
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Old Mar 21, 2012, 10:01 PM
Balsa and Foam can Coexist
WAGliderGuy's Avatar
United States, WA, Seattle
Joined Feb 2010
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Wing Panels

After labeling all 271 laser-cut parts and making sure I got all 500+ feet of wood from NationalBalsa, I layed down the plans and started the left wing panel and bowing patterns. Mostly straightforward except the error in the plans on the aileron placement. Since its on both sides, I'm not going to worry about it. The balsa from National is the hardest stuff I have ever felt! This is good for the fuselage structure and main wing spar but it made the bowing outlines a nightmere.

I was able to make up the horizontal stab bow tips and vertical stab outline but the larger wing tips just didn't work. So I went to the LHS knowing it would be alot softer. Well guess what? The wood was so soft that even after a minimal soaking time it kept kinking! Oh well, I just went with the smaller size harder balsa. A little sanding and covering technique will cover it up.

Here is where I currently am. The pen marks are the flap cut outs but I am going to change it to roughly a 30-40 degree to minimize the gap on top.



More pictures down below. I hope to have the first build video up soon which will include video footage and more photos.

I hope to finish the nacelles and maybe even the retract mounts this weekand so stay tuned!

Ethan
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Old Mar 22, 2012, 12:42 AM
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Spitfire1954's Avatar
United Kingdom, England, East Riding of Yorkshire
Joined Jan 2011
607 Posts
Nice job – look forward to seeing the end result!
Good luck with your build.
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Old Mar 22, 2012, 07:37 AM
1:1 scale is fun!
ECBoehm's Avatar
United States, NJ, Midland Park
Joined Feb 2009
456 Posts
I have better luck bowing basswood strips. A fractional increase in weight but makes a more resilient tip as a bonus.
Good luck with the project, I have this on my "someday" list so I'll be interested in your progress.
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Old Mar 22, 2012, 11:20 AM
Veni Vidi Volavi
Sterling, VA
Joined Jan 2002
2,459 Posts
Ethan

Nice looking scheme. My Tritle DC-6 has been done up as a MAC C-118A Liftmaster (picture follows). Mine uses 12 mm Feigao's in the GWS IPS-B boxes on three cells. As a side note you do not need to use counter rotating props, plane tracks as straight as an arrow with all four turning the same way. Mine weighs about 35 oz ready to fly. Looks simply spectacular in the air and ya gotta love the sound of four turning. I used a lot of basswood for the fuselage stringers as I am constantly breaking them when I pickup the uncovered fuselage of a Pat T design. Pat must have some soft hands, I can break a fuselage stringer on one of his designs just by looking at it the wrong way. I usually use basswood where I think I will be handling it and picking it up and use balsa elsewhere.

Brian Allen

Veni Vidi Volavi

I came I saw I flew
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Old Mar 22, 2012, 10:38 PM
Balsa and Foam can Coexist
WAGliderGuy's Avatar
United States, WA, Seattle
Joined Feb 2010
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Thanks guys

ECBoehm - never though of that, I might need to make a new and sturdier rudder outline so I will try it out.

Brian - I got lots of extra basswood after seeing your posts in Pat's thread. I plan to 'borrow' your internal linkages too

Ethan
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Old Mar 24, 2012, 06:33 PM
Balsa and Foam can Coexist
WAGliderGuy's Avatar
United States, WA, Seattle
Joined Feb 2010
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Flap Modifcations

It took me awhile but I now have flaps! I cut the left ribs out first then measured 1cm back on the bottom of the removed flap ribs and cut 35 degrees or so out of each one. Next, I cut out a new spar that continues from the aileron spar and added that. Same thing for the flap spar. Then I added a 1/16'' balsa flap gap on top, hinged the whole deal and I was in buisness. I did a lot of sanding on the bottom of the flap to makesure there is a flush finish from the wing to the spar when deployed because this is a barn-door style hinge.

Did the same thing on the right but instead cutting out rib 3, I did the opposite and kept it there and made my own flap rib. When I post the video, it will make more sense

I am planning on adding the servos on rib 4/4A.

Starting on the nacelles now

Ethan

Completely forgot to upload the pictures of our good camera ($$ canon) so it will be in Maui with my freind for a few days before I get the SD card back In the mean time, I snapped a few right before I finished hinging with an older Nikon.
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Old Mar 26, 2012, 09:24 PM
Balsa and Foam can Coexist
WAGliderGuy's Avatar
United States, WA, Seattle
Joined Feb 2010
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Servos and Motors

Got the servos mounted. I will have to cut new slots for the control horns on the ailerons because the 9G servos are longer. I wanted to cut into the ribs to avoid this but the balsa is so soft it probally would have destryoed it

The flap servos were the hardest and I eventually decided on putting the left flap servo on rib 4 so it sits right behind the retract mount. The right servo was the tough because I had to put it on rib 5 and the whole piece is basically a lighting hole. I tacked it to the bottom portion then added a good amount of 1/8'' balsa sticks around.

Once the stringers go in, everything will be nice and solid. Lets hope that nothing dies on me because there is no getting them out with breaking the rib even though there is tape around the servo. Brian, I planned on using your removable hatch method but I really don't feel like putting all that extra time in.

I have seen a few complaints on the nacelles being a little to vibration prone with these small brushless motors so I want to try and elminate any headaches that could happen later by changing them to sheet. tooutal did this in his thread.

So I made the four outer necelles out of 3/16'' stock balsa (twice as thick as the 3/32'' stringers) but the problem with the inner necelles is getting a tandem wheel set to fit into them. So I got some 3/32'' basswood and cut some sides up using the band saw.

Before I started assembling them, I mounted all the motors on the ply firewalls. What I thought would take me less then hour took almost three because I decided to add beveled edges with a file for the set screws to bite into on the motor shaft (where the mount attatches). I read that these small motors have a problem with the mount coming loose from the shaft so this modifaction plus some loctite should really help. Four motors is starting to become a royal PIA and I haven't even started the soldering and wiring

One final note, the power-up 250 plus motors I am using do not line up with the RCHotDeals holes so I had to drill some new ones and wick in some thin CA.

Slowly getting there!

Ethan
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Old Mar 27, 2012, 08:51 PM
Balsa and Foam can Coexist
WAGliderGuy's Avatar
United States, WA, Seattle
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Video is up:

Tritle Douglas DC-6B (F) Build Part One (9 min 31 sec)


Ethan
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Old Mar 27, 2012, 11:32 PM
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Great work Ethan ! Best luck with your DC-6 . . .
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Old Mar 28, 2012, 11:33 AM
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San Bernardino California U.S.A.
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Wow! This should be very interesting! I'll follow this build! I like what i'm seeing so far!

Laramie.
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Old Mar 28, 2012, 02:17 PM
Balsa&Tissue
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United States, OR, Beaverton
Joined Jan 2011
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Ethan,

I have 2 DC-6B's now and they always vibrate at about 85% throttle and higher. It is always the outer nacelles and when it happens it can be really destructive. The plane was designed for geared motors turning larger props at a lower RPM so it probably was not a problem with the original design.

Before I knew about the problem I would shed propellers from the outer nacelles. They would actually throw a blade and the out of balance vibration would cause me to land with almost no power. Also, I had a one throw a blade vibrate violently and when I landed the nacelle was partially destroyed with a prop blade stuck through it!

Anyway, it is a mechanical resonance that occurs at a certain RPM/frequency. It is a resonance based on the structure and beam lengths involved. It won't hurt to beef up the outer nacelles but the resonance will very likely still be present. The trick with brushless motors is to use low KV motors and use motors with enough power/thrust so you never need to go over 85% throttle.

The good news is the 250 plus motors have more than enough power. I think on my 80" version (370 sized motors) I will edit the throttle curve so that 85% throttle will be at maximum stick deflection so I cannot exceed the RPM that will damage the plane. On power testing the vibration was there at exactly the same power level as the 60" one! I used paulownia wood (4x stronger than balsa, similar to spruce) for stringers in the 80" plane to stiffen the nacelles but it is still a problem.

With the 250 plus motors make darn sure you loctite the grub screws in the motor mount and maybe even replace them with screws that have phillips heads. The original grub/set screws had 1.5mm hex drives and you couldn't torque them to an adequate value to keep em in or the heads would strip. These motors will try to fly their way right out of the mounts and if that happens you will be in trouble cause the motor will get loose and tear up the nacelle and it will be almost like a dead stick landing. I had it happen twice. The good news is this plane will fly on 2 motors and will also behave well on a dead stick landing.

Keep at it cause you will love flying this machine and it is impressive in the air. With flaps mine flies so slow that on approach I was actually passed by a glider.

Dave
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Old Mar 29, 2012, 07:21 PM
Balsa and Foam can Coexist
WAGliderGuy's Avatar
United States, WA, Seattle
Joined Feb 2010
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Dave,

I'm going to replace the grub screws and I have already added flat spots to where they bite into the shaft. Did you use the stock firewalls or longer prop adaptors? I have cut off the edges on the firewalls so I can move them forward and add them to the sheet sides. A little triangle stock and hopefully I won't have any problems for awhile

What guage wires did you use for the motor extensions?

Thanks!

Ethan
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Old Mar 29, 2012, 07:49 PM
Balsa&Tissue
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United States, OR, Beaverton
Joined Jan 2011
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Ethan,

I basically used the adapters you have that came with the motors. I just placed the firewalls so the cowlings were just behind the props for clearance.

Beefing up the firewall joint with some tri-stock is a good plan to fight any structural stress from the motors. One of my flights ended because of vibration and a firewall breaking loose.

I can't remember the exact size wires but I think they were 18 ga. However if you do a Google search for "ampacity of copper wire" you can find the info. Because of weight concerns I kind of consider that I am never going to sustain long periods over about 60%. Plus, the wire from the outboard motors only needs to handle the current of one motor so I kept the outboard motors on the lighter gauge side. Form the inboard motors to the battery is hwere it matters more but again I applied the 60% rule and went lighter. Don't be fooled by the charts that are for house wiring but look for DC chassis wiring numbers like typical electronic hook-up wire charts.

Edit: Here is the best chart..... http://www.powerstream.com/Wire_Size.htm

Dave

Quote:
Originally Posted by WAGliderGuy View Post
Dave,

I'm going to replace the grub screws and I have already added flat spots to where they bite into the shaft. Did you use the stock firewalls or longer prop adaptors? I have cut off the edges on the firewalls so I can move them forward and add them to the sheet sides. A little triangle stock and hopefully I won't have any problems for awhile

What guage wires did you use for the motor extensions?



Thanks!

Ethan
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Old Mar 30, 2012, 01:04 AM
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United Kingdom, England, East Riding of Yorkshire
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Keep up the great work Ethan! – this will be a beauty when completed
Charles
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