Cessna Crane scratch pub build

Started by Wingnutz, March 31, 2013, 08:13:15 PM

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Wingnutz

Three years ago, over a pub lunch, Dad and I decided to jointly build a model of an aircraft he trained on during WWII. The real plane goes by many names...Cessna Crane in Canada and; Cessna Bobcat, T50, AT17, UC78, Bamboo Bomber, Witchita Wobbler and finally, (I think...LMK if you find any other names for this one!) the Songbird (are you old enough to have watched Sky King?)!
The Canadian government ordered over 800 of these during WWII for the Commonwealth training plan and virtually assured the survival of the Cessna aircraft company at a time when its future was not so assured. They were used as advanced twin engine trainers following basic multi engine training.
There are no RTF, BNF, PNP or even ARF versions and no kits...unless you want to build a Don Smith kit at 101"WS (maybe later) or pay over $400 for a Thomas Designs 42" kit...KIT!!!
Found a set of plans for a 1/12 scale version (42") and ordered. Naively,(I've never built from plans...Dad has) I chose to build the wing...double taper, semi-symmetrical with cylindrical, tapering nacelles on each wing...not really a beginner's build.
Although the plan proved useless for anything except wing ribs, Dad had the fuselage framed up in a couple of weeks...I was still cutting ribs. Dad got impatient with my progress and moved on to other models. I'm on the third wing and have inherited the build...it's finally coming together.
I've included photos of the early wings, abandoned because of weight (wing #1) and lack of skill and knowledge on my part (wing #2).
Other photos are of the recently built tail feathers and one of 7682 which is presently in the Canadian Warplane Heritage Museum in Hamilton. I'll post more photos later.
DOWN WITH GRAVITY! UP WITH LEVITY!

piker

It's starting to look good, Bill.  I know it must be hard figuring out how to build a framed model from scratch without a good plan or several good kit builds under your belt.  Following the construction style of the Norseman for the wing would probably bee a good start.

A good, basic, built up wing will have a top and bottom spar at the thickest point of the rib, with a solid, or top and botton strip, trailing edge and a "D Tube" construction at the front.  "D Tube" means that the wing is sheeted ahead of the main spar (to the leading edge), top and bottom.  it is remarkable how stiff an otherwise flimsy wing will become with the addition of some light sheeting like that.  The addition of rib cap strips between the spars and trailing edge makes for a very nice looking wing that's light and stiff.

Keep up the great work.  It's looking good.

BTW, Andre built a Cessan Crane many years ago.  It was a cool plane.

Robert

Wingnutz

#2
Rob,
Thanks for the words of encouragement.
The third wing is essentially complete...I really wish I'd had the benefit of the Norseman build before I tried to build the Crane wing. I used a single piece of 1/16" ply for the main and the drag spar. I cut the bottom off of each rib so it would be flat, notched each rib and fitted them egg-crate style to the spars which had also been notched. I built one side on a flat surface, then tipped the whole assembly so I could build the other side on a flat surface and finally glued the curved sections back on the ribs. The stricture was pretty floppy until I added some sheeting and created a variation on the D tube...and a surface to which the. nacelles could be fitted.
The nacelles were a challenge as the plans didn't include nacelle former shapes. Created a ply nacelle spine for each wing which was a sort of enlarged and extended rib.
About this time, I found the perfect sized nacelles and cowlings from Park Flyer Plastics and they solved much of
that challenge...but not the challenge of fitting curving cone shaped nacelles to a semi-symmetrical, double tapered wing...*#%£ing nothing was straight!
Anyway, have attached photos of the wing details and the wing itself...will post more photos later
DOWN WITH GRAVITY! UP WITH LEVITY!

Papa

A motto to live by:
"What other people think of me is none of my business"

piker

You're really moving along... covering and all!  Lookin' good!

Wingnutz

#5
Quote from: piker on April 03, 2013, 10:21:02 AM
You're really moving along... covering and all!  Lookin' good!
Dunno if three years to this point is really moving along but the model is progressing.
Included a picture of tihe windshield area which we had to thermo vaccuum form. Dad carved. I built the vaccuum box and pulled.
Added 1/64 ply sheeting to the fuse sides, mounted the rudder and elevator servos, covered the tail feathers anddiscovered one aileron servo had ceased functioning. #*!T...didn't learn about tubes for servo leads until Norseman class! It's things like this that make me grateful for the TEMAC scratch classes. Trial and error is a brutal teacher! Anyway, after hacking access holes in the underside wing sheeting, both aileron servos are again working. Did I mention this is my first balsa build in ** years?
Props this evening. Both motors ARE working.

Steve, I need you to grind the numbers for my power system choices.
Model should come in at 1.5-2.0 pounds
Motors ..Park 300's 1080kv
ESCs 12A
1300mah 3S
Props...counterrotating 7x5Es APC
DOWN WITH GRAVITY! UP WITH LEVITY!

Wingnutz

#6
Gave the model back to Dad two weeks ago so he could finish the fuse. Would love to have done it myself but our agreement three years ago was he'd do the fuse and I'd do the wings. We never did decide who'd do the tail feathers so I did them.
The windshield fit isn't great so Dad's re-working the plug and I'll pull the new hopefully improved one. We're hoping she'll be ready for TEMAC's Warbird Day as the aircraft was a WWII trainer.  Time permitting we're going to do the model up as one that was stationed at RCAF Station Dauphin Manitoba...8848 which is one Dad flew and has quite a story attached to it. Here's what the internet records for this aircraft
"8848 Cessna Crane Mk. IA 2398
first date: 13 April 1942 - Taken on strength by No. 1 Training Command
Also received RAF serial FJ197 and USAAF serial 42-13714, no record of either ever being marked.  First assigned to the Central Flying School at RCAF Station Trenton, Ontario.  To No. 3 Training Command on 4 June 1942 for use by the Test and Development Establishment at RCAF Station Rockcliffe, Ontario.  To No. 2 Training Command on 27 November 1942.  With No. 10 Service Flying Training School at Dauphin, Manitoba when it suffered a Category A crash on 17 August 1944.  To No. 8 Repair Depot at Winnipeg on 19 August 1944 for scrapping.
last date: 1 September 1944 - Struck off, reduced to spares and produce" from RWR Walker's Canadian Military Aircraft
Serial Numbers

The bold line doesn't tell the human side of the story...so much for the Asian belief that 8's are lucky! That unlucky four must be a lot more powerful than the three lucky 8's! Sorry about the so so photos. Will post better ones when we have time to set the model up for photos.
DOWN WITH GRAVITY! UP WITH LEVITY!

petegeol

I was involved in the restoration of 7862 at Canadian Warplane Heritage and subsequently flew the Crane from 1987 to 2000

7862 like the aircraft you are modelling had a crash incident - started at No 4 SFTS in Saskatoon and after major accident was rebuilt in Winnipeg and ended its BCATP career in Yorkton.

The CWH Crane never stopped flying after the war.  First owner was with Matane Airservice in Gaspe (owned by an Aussie who had trained on Cranes, married a Canadian girl, survived the war and started a flying service in the 1940's), then to an Ottawa private owner and in the late 70's was donated to CWH and we started an 8-year restoration (sounds a bit like your project, just on a larger scale) with the first test flight was in the fall of 1986 and I completed my check ride in the spring of 87 in time for the Hamilton Airshow in 1987.

Sure would appreciate jpeg photo of your finished product.

Also the exposed frame of your fuselage  (other than being wood) is almost identical to the original tubular steel frame with rounded wood fillet along the top.

Hopefully you will get airborne this year.  Attached are a couple of before and after pictures of 7862 (1979 and 1987)

Regards, Peter George

petegeol

Sorry - here is the pre restoration picture of 7862

Wingnutz

#9
Pete?
Hope I got the name right. Wow! Thanks for the pre-restoration photo of 7862! Had no idea that aircraft had such a "colourful" history or that we had a forum contributor so personally involved with a "warbird" (it's warbird weekend)
You seem pretty knowledgeable about RCAF Cranes so perhaps you can tell me if the aircraft serial number is displayed on the real aircraft as it was on RAF and RCAF combat aircraft?

BTW Dad and I enjoyed the Crane build enough to plan an Avro Anson build for the winter of 2013-2014. We've got the plans and will probably order the available short kit to shorten the time for the build. It'll be done up as an Anson II which Dad flew out of Summerside PEI and will be twice the size of the Crane model at 84" WS. Gave him the plans at yesterday's pub lunch.
DOWN WITH GRAVITY! UP WITH LEVITY!

Ededge2002

Yes Peter thanks for your contributions to the tale of this aircraft. Very cool to read
Yea 400W/lb should about do it.. But wouldn't a nice round 500 be better?

Wingnutz

Okay, first scratch build I've been involved in...started in early 2010 and finally...the maiden, today, October 30, 2013! Okay so I 'm really slow(at building...probably other stuff too!). I struggled with the build and watching the little Crane (42") carve up the skies over ROGO today, it was worth it! I had fun and learned a lot! Thanks to Graham McNicol and his kids for the video and a.m. Frank for the launch! Youtube link below.
http://youtu.be/HdsgMoa5B70
DOWN WITH GRAVITY! UP WITH LEVITY!

Ededge2002

Great job Bill and associates. Your enthusiasm at the end of the flight is terrific. Congratulations.
Yea 400W/lb should about do it.. But wouldn't a nice round 500 be better?

Michael

Michael

Papa

Well done Bill, nice flying and an even nicer landing.
Great video record Graham!

It's not how long it took to build that matters.
It's how long it took for the grin to stop.

Jack.
A motto to live by:
"What other people think of me is none of my business"