FDM - 150" Ford Trimotor in DTFB! (1/6 Scale)

FoamyDM

Building Fool-Flying Noob
Moderator
This week I managed to open my mouth and agree to a challenge to build a DTFB model of a 150" Wingspan Ford Trimotor

1653425396076.png

Why this plane?:
A long while ago, Ron and Tom from the RC plane Lab Podcast (great podcast) announced in Episode 56 (Feb 12th of 2021) That they were going to build a Ford Trimotor with a 145" wingspan! They have ordered the Balsa... and other than motor talk, that is really all that we heard. After hearing that episode, I thought it would be a fun and loving poke to design an all-foam Larger model. I have three (one on the way) 5010 with 15x5.5 CF props (made for an agricultural drone) and this project looks like a great choice for them, and a great challenge for me.
1653425035293.png vs, 1653425112034.png

Plane History:
1653432572287.png
First flight - June 11, 1926
Manufactured by Stout Metal Airplane Division of the Ford Motor Company
William Bushnell Stout sent a letter to several leading manufacturers asking for $1,000 investment with the statement “For you one thousand dollars you will get one definite promise: You will never get your money back.” Presumably to start the Stout Metal Airplane Company.
All-metal constructions. Exterior skin was corrugated aluminum. Increased drag from the corrugation caused reduction in overall performance.
Interesting bit, the fuselage and wings followed designs by Junkers used in their Junkers J.I, Junkers F.13, Junkers K 16, and Junkers G 24. Junkers sued Ford when Ford attempted to export the Trimotor to Europe and won due to how similarly the Trimotor was to Junkers designs.
Designed primarily for passenger use (11 passengers), was easily adapted for hauling cargo. The inside of the wings could be accessed from the inside of the fuselage for baggage space.
As the name suggests, had 3 motors. Could run without the center engine well enough, but losing one of the side motors was far more problematic.
Utilized a hand operated “Johnny brake.” with such a long handle it needed to be passed to the co-pilot to operate effectivly.
1653432535974.png
General characteristics
  • Crew: 3 (pilot, co-pilot, flight attendant)
  • Capacity: 11 passengers
  • Length: 49 ft 10 in (15.19 m)
  • Wingspan: 74 ft 0 in (22.56 m)
  • Height: 11 ft 9 in (3.58 m)
  • Cabin length: 16 ft 3 in (5 m)
  • Cabin width (average): 4 ft 6 in (1 m)
  • Cabin height (average): 6 ft 0 in (2 m)
  • Cabin volume: 461 cu ft (13 m3)
  • Empty weight: 6,500 lb (2,948 kg)
  • Gross weight: 10,130 lb (4,595 kg)
  • Fuel capacity: 231 US gal (192 imp gal; 874 l)
  • Oil capacity: 24 US gal (20 imp gal; 91 l)
  • Powerplant: 3 × Wright J-6-9 Whirlwind 9-cylinder air-cooled radial piston engines, 300 hp (220 kW) each for take-off
  • Propellers: 2-bladed fixed-pitch propellers
Performance
  • Maximum speed: 132 mph (212 km/h, 115 kn)
  • Cruise speed: 107 mph (172 km/h, 93 kn) at 1,700 rpm
  • Stall speed: 57 mph (92 km/h, 50 kn)
  • Range: 570 mi (920 km, 500 nmi)
  • Service ceiling: 16,500 ft (5,000 m)
  • Absolute ceiling: 18,600 ft (5,669 m)
  • Absolute ceiling on 2 engines: 7,100 ft (2,164 m)
  • Rate of climb: 920 ft/min (4.7 m/s)
  • Time to altitude: 7,200 ft (2,195 m) in 10 minutes

Plans: (21 sheets)
Alpha Plans:
Alpha-PlanSet.GIF

Build Log In brief:
I will start out with this estimates for this model.
I estimate this model to have a Wingspan of 150" (it is important that I declared a larger wingspan than Ron from RCPL[~146"]. I want to see if he creeps his WS to surpass 150")

Estimated Model Specs


Estimated Weights​


Wings:
WS = 150"


12x115gx90%=1242g​


Fuselage:
Length = 90",Height = 34"


12x115gx85%=1173g​


Covering & glue


200g​


Motors = 5010 340kv pancakes - 3.04kg of thrust


3x175g=525g​


15x5.5 Carbon Fiber prop


3x15g= 45g​


3 - ESC opto - 35A, 2S-6S


15gx3=45g​


1 BEC 5V-26V 5V/3A or 12V/3A & Reciever


26g​


2 x 6000mah 6S 50C batteries


2x 863g = 1726g​


Servos x4 25kg torque,


4x75g= 300g​


Landing Gear


2x200g= 400g​



Estimated Total Weight



5,679 g (12.78) lbs


Model Shoot:

Maiden Flight:

Take Aways:
Things I'm pleased with

Thing I should have stopped doing

Surprises
 

Attachments

  • FDM FTM A1.0.pdf
    343.8 KB · Views: 0
Last edited:

Baron VonHelton

Elite member
Hmmmmm........The Ford Tri-Motor I flew in as a boy was nowhere NEAR as posh on the inside, and didn't have the camel hump cockpit. Maybe I flew a cargo version with some seats bolted in. Everything on that plane rattled as if she was gonna shake apart. But, I got there & back without incident.

:cool:
 

FoamyDM

Building Fool-Flying Noob
Moderator
I went to the DTFB store. And shopped around for supplies for this beauty. Picked up 3.3kg worth. I think the broom handles will make a great spar.
IMG_20220524_204215138.jpg IMG_20220524_204206974.jpg
 

Baron VonHelton

Elite member
The unique feature of the FORD Tri-Motor is the ribbed wings & sides. Note the external servo as well.

Ribs - FORD Tri-Motor.jpg


I remember the ribbing being unique to other airplanes at the time. Not sure how to duplicate it, TBH.......

:cool:
 

Baron VonHelton

Elite member
I disagree VEHEMENTLY with the article. The ribbing IMPROVED airflow over the surfaces, thus reducing turbulence. This is why Junkers did it IN THE FIRST PLACE.

:rolleyes:
 

FoamyDM

Building Fool-Flying Noob
Moderator
added specs to post #1. they were notes more than an article. The flutes add more skin surface and therefore some drag, however it must have been offset by the improved airflow/reduced turbulance. no need to be upset. Thanks for pointing it out though.

That 10' model out there that is well done! (post#4) Thanks!
 

FoamyDM

Building Fool-Flying Noob
Moderator
Currently finishing the 3-4 projects on the build table to clear it for this!
 

Baron VonHelton

Elite member
added specs to post #1. they were notes more than an article. The flutes add more skin surface and therefore some drag, however it must have been offset by the improved airflow/reduced turbulance. no need to be upset. Thanks for pointing it out though.

That 10' model out there that is well done! (post#4) Thanks!
It's all good.......
(y)
 

Tench745

Master member
"How's this build coming," I ask, tongue-in-cheek.
My dad got a few minutes of stick time in a Trimotor this weekend. I intend to record his pilot report while he's visiting and share it if anyone is interested.
 

bwarz

Master member
The unique feature of the FORD Tri-Motor is the ribbed wings & sides. Note the external servo as well.

View attachment 226225

I remember the ribbing being unique to other airplanes at the time. Not sure how to duplicate it, TBH.......

:cool:
quite some time ago I designed and 3D printed 'molds' to form heavy aluminum foil into corrugated metal for my train layout. You just cut the aluminum foil into HO scale metal sheets and pressed it between the molds and voila! corrugated sheets! I put the plans on Thingiverse -->here<-- if you wanted to give it a try. I see there are other similar contraptions on there as well (I guess that is if you've got a 3D printer...)
 

bwarz

Master member

FoamyDM

Building Fool-Flying Noob
Moderator
"How's this build coming," I ask, tongue-in-cheek.
My dad got a few minutes of stick time in a Trimotor this weekend. I intend to record his pilot report while he's visiting and share it if anyone is interested.
I hope you did. I would love to hear that!
 

FoamyDM

Building Fool-Flying Noob
Moderator
It came here the weekend of my birthday - we didn't know it they were doing flights and I looked it up after seeing it fly over for a few days. They did one extra flight for some stragglers and my wife pushed me and three of my boys got to take the ride!
Awesome! share your impressions. And your boys reactions. yours... I want to know.

quite some time ago I designed and 3D printed 'molds' to form heavy aluminum foil into corrugated metal for my train layout. You just cut the aluminum foil into HO scale metal sheets and pressed it between the molds and voila! corrugated sheets! I put the plans on Thingiverse -->here<-- if you wanted to give it a try. I see there are other similar contraptions on there as well (I guess that is if you've got a 3D printer...)
Thank you @bwars. I plan to give it a Try. It my the next Giant Scale build.
 

Baron VonHelton

Elite member
quite some time ago I designed and 3D printed 'molds' to form heavy aluminum foil into corrugated metal for my train layout. You just cut the aluminum foil into HO scale metal sheets and pressed it between the molds and voila! corrugated sheets! I put the plans on Thingiverse -->here<-- if you wanted to give it a try. I see there are other similar contraptions on there as well (I guess that is if you've got a 3D printer...)

Very nice! (And handy!)

(y)