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Very Hot Topic (More than 25 Replies) Interested in a winter trimotor cookup (Read 8723 times)
alfakilo
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Re: Interested in a winter trimotor cookup
Reply #33 - Jan 29th, 2019 at 1:36pm
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On to the stab and wing engines.
  

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Sky9pilot
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Re: Interested in a winter trimotor cookup
Reply #32 - Jan 29th, 2019 at 10:26am
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Love the caricature of the "125" Grin Cheesy Wink
This is going to be a very interesting model.  I look forward to your approach!
Tom
  

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Kerak
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Re: Interested in a winter trimotor cookup
Reply #31 - Jan 29th, 2019 at 10:21am
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I've found that a nice box sub-structure fuselage allows for considerable weight-savings.  On the other hand...on a model that utilizes anything more than flat sided surfaces...gets a bit more involved.

As Alf stated...a good 3-view is the key to a buildable plan.

Here's my latest struggle thus far....fuselage is about 16" in length.  I've actually considered constructing a simple box fuselage model...forget all the curves.  Wink  Don't believe this is an exact scale endeavor....

Incidentally, the YC-125 was the last propeller-driven tri-motor configuration aircraft used by the United States military establishment.

Neal
  

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alfakilo
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Re: Interested in a winter trimotor cookup
Reply #30 - Jan 29th, 2019 at 7:07am
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bigrip74 wrote on Jan 28th, 2019 at 9:05pm:
alf, how did you draw you plans so fast? Great job Smiley on a really interesting airplane.

Bob


Bob, usually I don't take the time to draw a plan in the conventional sense. I've found that the fuselage is typically the most difficult part to get right. If I can find a three view that can be enlarged then I'll use it to estimate the shape of fuselage formers. I like the keel method of construction much more than the box method.

For the Couzinet, I found a website that had pictures of fuselage formers of the actual aircraft and used those to start the project. I'm using a cracked rib method for the wing that makes things easier as well.

Finally, Mike mentioned the wing fillets. There were a number of versions of this aircraft with differences primarily in fuselage length. The long version used a large fillet that I'm planning on avoiding for three reasons...too much work, I don't like the looks of it, and I don't think it is aerodynamically necessary in model of this size. So, I'm making a composite model that blends the best parts of the 70 and 71 versions while keeping the build simple and easy.
  

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bigrip74
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Re: Interested in a winter trimotor cookup
Reply #29 - Jan 28th, 2019 at 9:05pm
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alf, how did you draw you plans so fast? Great job Smiley on a really interesting airplane.

Bob
  

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Re: Interested in a winter trimotor cookup
Reply #28 - Jan 28th, 2019 at 12:12pm
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Love the RATO picture!

Mike
  
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Kerak
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Re: Interested in a winter trimotor cookup
Reply #27 - Jan 28th, 2019 at 12:00pm
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Looks like we've already started....  Northrop YC-125 Raider was an aircraft contracted for by the AAF/USAF in 1946 to fill the need for a purposely designed arctic transport/rescue mission.  Obviously three engines were considered more reliable than the conventional two under such extreme operating conditions.  As things turned out, the YC-125's operational career with the military was relatively short lived (ten years).  I can see a Fairchild C-119 hidden in that fuselage...or even a future C-130. Wink  Northrop's design did soldier on as a civilian passenger ship well into the 1950's.  Two examples exist today...one at the Pima Air and Space Museum (AZ) and the other at the National Museum of the United States Air Force (OH).

Like Alf stated...slow going, design as we go...a rare bird (no plans)...the Northrop YC-125 Raider (mil) or Pioneer (civ).  Key was to find a decent 3-view that can be utilized as a building plan...arrange the layout for modification...convert to PDF for scaled printing...and then have at it.  Last plan view is of a solid carved model from 1950...gives me a clue as to bulkhead shapes...not that I'll stick with it.  Grin

I'd like to create a box fuselage...but it might be easier to go with the half-shell system.  I'm looking for quick n' easy as possible.  Model will have a 20"ws.

Neal
  

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Re: Interested in a winter trimotor cookup
Reply #26 - Jan 28th, 2019 at 9:23am
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Great start AK - and you thought the fillets on the Gamma were big!

I pulled out the SM.79 plan this morning - forgot how big a model this is (34-3/4" span).  I can see some structure changes I want to make and I'll have to decide whether I want to scale it down a bit.

Great to see airframes coming together already.

Cheers,

Mike
  
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Re: Interested in a winter trimotor cookup
Reply #25 - Jan 27th, 2019 at 9:41pm
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Yep, Tom, I agree. Used the Dremel this afternoon to hollow out the formers before any more stringers went on. I'm using soft wood, 1/32 formers and stringers, so it was a chore with a number of broken pieces. The extended tail is particularly fragile since it's mostly two dimensional with little cross bracing.
  
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Re: Interested in a winter trimotor cookup
Reply #24 - Jan 27th, 2019 at 8:35pm
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AK...that's looking great.  If you're going to run a central prop, you might want to start the holes in the formers while they're easy to get to.  I love the look of it already!! Smiley

I've started the Rohrback Roland from the color three view but the plan and side view are not to scale with each other so some tweaking was required.  We'll see how this comes out!
Tom
  

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Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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Re: Interested in a winter trimotor cookup
Reply #23 - Jan 27th, 2019 at 11:19am
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AK - Really nice beginning. I'll be watching along.
Mike
  

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alfakilo
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Re: Interested in a winter trimotor cookup
Reply #22 - Jan 27th, 2019 at 11:06am
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Off and running on the Couzinet. Given the variety of similar looking versions, this will be a combination of the 70 and 71.

No plan so it's build as you go with considerable fitting and adjusting along the way.
  

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bigrip74
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Re: Interested in a winter trimotor cookup
Reply #21 - Jan 25th, 2019 at 6:06pm
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Tom, here are some research photos and a couple of links on the Rohrback.
  

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Re: Interested in a winter trimotor cookup
Reply #20 - Jan 25th, 2019 at 5:34pm
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That would be a real neat peanut Bob!!!  I'm considering drawing up the Rohrback VIII Roland for you and myself!  I love the looks and the scheme!
Tom
  

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Your attitude will determine your altitude!- John Maxwell
And ye shall know the truth, and the truth shall set you free. Jn 8:32
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bigrip74
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Re: Interested in a winter trimotor cookup
Reply #19 - Jan 25th, 2019 at 5:21pm
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Neal, that is  really good looking subject. Not too much bracing, engine nacelles, or intricate landing gear stuff Wink I just need to talk Tom into drawing up a set of plans.

Tom, I ran across this Stinson Model U trimotor which looks like an easier build than the Ford.
  

Stinson_Trimotor_oz1059.pdf ( 699 KB | 1 Download )

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