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Moment arm for W&B.

Posted: Tue Mar 25, 2014 11:50 pm
by T. C. Downey
what measurement in inches for the main gear and the tail wheel?

Re: Moment arm for W&B.

Posted: Wed Mar 26, 2014 12:04 am
by T. C. Downey
Aryana wrote:On a B model, I believe it is 110 inches from the firewall to the main gear and another 227 inches to the tailwheel.

http://www.cessna170.org/forums/viewtop ... ce#p100488
Knowing the bottom of the fire wall is the datum, it can't be 110 inches from there to the main gear.

Re: Moment arm for W&B.

Posted: Wed Mar 26, 2014 12:14 am
by T. C. Downey
Aryana wrote:According to the W&B from Cessna on my plane it is 22" from the firewall to the mains and another 227" from the mains to the tailwheel.
That's reasonable

Re: Moment arm for W&B.

Posted: Wed Mar 26, 2014 12:50 am
by T. C. Downey
Aryana wrote:I found a photo of a 170 online with a 110" arm to the mains. Field approval? :mrgreen:
1955_170B Cessna Ext from brochure.jpg
Photo chopping is a minor alteration. :)

Re: Moment arm for W&B.

Posted: Wed Mar 26, 2014 1:43 am
by Bruce Fenstermacher
From the TCDS

(a) 2 Main wheel 4 ply-rating tires, 6.00-6, 18 lb. (+22) (+22) (+22)

(a) Scott Model 3-24B, steerable 5 lb. (+246) (+246) (+246)
*(b) Scott Model 3200, steerable, swiveling 8 lb. (+249) (+249) (+249)

The A measure or distance from the datum to the main axle is 22".
The B measure or distance from the main axle to the rear axle is dependent on the tail wheel at either 224" or 227".

Of course this is under ideal conditions from the factory and in the case of the tailwheel isn't necessarily to the axle but the center cg of that part.

We all know it is not what the TCDS says but what your aircraft now actually measures. One could have 180 gear changing the main axle location and depending on the actual arc of your tailwheel spring the rear axle could be different. My own first 170 actually measured 22.4" for A and 228.68" for B when I carefully measured it over and over trying to match "factory" specs.

Re: Moment arm for W&B.

Posted: Wed Mar 26, 2014 1:44 am
by johneeb
Arish,
Is that some kind of green airplane speed mod? :P

Re: Moment arm for W&B.

Posted: Wed Mar 26, 2014 4:18 am
by Ryan Smith
Aryana wrote:I found a photo of a 170 online with a 110" arm to the mains. Field approval? :mrgreen:
1955_170B Cessna Ext from brochure.jpg
You're a day late and a dollar short. :lol:

Re: Moment arm for W&B.

Posted: Wed Mar 26, 2014 5:36 am
by T. C. Downey
34v turned out heavier than I wanted at #1325, #1287 with out the rear seat out,

Re: Moment arm for W&B.

Posted: Wed Mar 26, 2014 5:43 am
by T. C. Downey
Aryana wrote:On a B model, I believe it is 110 inches* from the firewall to the main gear and another 227 inches to the tailwheel.

*EDIT/CORRECTION: It is 22" from the firewall to the main gear, not 110"

http://www.cessna170.org/forums/viewtop ... ce#p100488
I was still giggling about the numbers and the wording. firewall to gear 110" plus another 227 = 337"/12 = 28 feet, but it still fits in my 30 foot hangar with the cowl on .i'm laughing with you, not at you :)

Re: Moment arm for W&B.

Posted: Wed Mar 26, 2014 2:17 pm
by GAHorn
T. C. Downey wrote:
Aryana wrote:On a B model, I believe it is 110 inches* from the firewall to the main gear and another 227 inches to the tailwheel.

*EDIT/CORRECTION: It is 22" from the firewall to the main gear, not 110"

From another thread:

http://www.cessna170.org/forums/viewtop ... ce#p100488
I was still giggling about the numbers and the wording. firewall to gear 110" plus another 227 = 337"/12 = 28 feet, but it still fits in my 30 foot hangar with the cowl on .i'm laughing with you, not at you :)
800px-Cessna.206h.stationair2.arp.jpeg

Re: Moment arm for W&B.

Posted: Wed Mar 26, 2014 6:04 pm
by blueldr
George,
Has that 206H got a retractable tail wheel?

Re: Moment arm for W&B.

Posted: Wed Mar 26, 2014 7:24 pm
by GAHorn
You'll have to ask the original poster. I only copied it from another thread.