Phillip,
I'll attach the spreadsheet for you to look at -- I'll hold off posting it until I go over it a few times. The graphical method seems a little labored. I can make mistakes, but most of it is pretty basic; I do this for a living. skinny dragon on page 1 fat dragon on page 2. Although if you EVER plan on selling it it would seem like you might want just a little more payload. I think the weight penalty is not high. Maybe 180 limit on the pilot might be OK.
Kenny



--- On Sun, 10/2/11, Philip Lardner <This email address is being protected from spambots. You need JavaScript enabled to view it.> wrote:


From: Philip Lardner <This email address is being protected from spambots. You need JavaScript enabled to view it.>
Subject: RE: [Carbondragonbuildersandpilots] Re: Wing calculations
To: This email address is being protected from spambots. You need JavaScript enabled to view it.
Date: Sunday, October 2, 2011, 5:59 PM


Hi Kenny,

I'm sending you the attached pages of Marske's manual (off-list, as it is copyright material) so you can see how I am arriving at the figures in my spreadsheet and other pages of notes.

I'll leave off asking any questions until I've had a chance to see your spreadsheet and the numbers you're using... but I've already got a few!

Glad you're on the mend!

Phil.

---

From: This email address is being protected from spambots. You need JavaScript enabled to view it. [This email address is being protected from spambots. You need JavaScript enabled to view it.] On Behalf Of Kenny
Sent: 02 October 2011 13:14
To: This email address is being protected from spambots. You need JavaScript enabled to view it.
Subject: [Carbondragonbuildersandpilots] Re: Wing calculations



OK, I FINALLY got a chance to go over the calculations (the bronchitis is down to a dull roar) . I don't have Marske's book, so it was hurting my brain trying to figure out how he did everything, so then I thought, I'd just do it the 'real' way (LOL). so I just made my own spreadsheet and ran the numbers for the wing I was thinking of it. Calculate the area, the wing loading and then the moments and cap (flange) loads. Our solution tracked OK until you go to calculate the load in the flange. The load in the flange is just the moment divided by the height.

At the root for 8gs you got a moment of 112,951 in-Lb (I got 109,000). The height of the outer contour is 11.75 at the root, but I used 11.5 to account for any offset

The cap load is then: 113000/11.5 = 9826 Lb
you got 19226 Lb

One thing I did to make sure I didn't get confused is I kept all the units in inches. I upload my spreadsheet once I get my wing straightened out. I put the standard wing on page 1 and I'll put my wing on page 2. I'm using:

pilot weight 220
parachute 25
air frame weight 155
wing weight -75

I'm using 6g limit, 9 g ultimate (that's the same as an F-16! -- I think it will be enough!)

A word about sizing the wing. There is a couple of things that we can do to simplify the analysis and that is a decision to keep the upper and lower wing spar sizing symmetric. It won't cost much weight due to using the carbon spar caps. We do that and the centroid is in the middle and we can use P_cap = M/h to calculate the load in the cap (easy-peeze).

So you size just one spar for ultimate load, and that's good enough. because carbon fails catastrophically, there is no need to be concerned about limit load. Limit load is only used to check for yield. For virtually all aerospace-grade aluminum (other than 6061) , and graphite limit checks are not necessary.

Also, I'm going to be a bit more sporting than my buddy and use 150,000 psi for compression in the carbon rod [rather than 100,000] and just make damn sure I pack everything right into the corner. Between using the lower allowable and making the wing cap sizing symmetric, it should be plenty conservative. Check your spreadsheet for that cap load.
Kenny

--- In This email address is being protected from spambots. You need JavaScript enabled to view it., "Philip Lardner" wrote:
>
> Ok, I've updated the Excel spreadsheet in my files directory with a new
> sheet detailing the Rib Stress Analysis for each of the ribs in the main
> wing.
>
> Phil.
>
> _____
>
> From: This email address is being protected from spambots. You need JavaScript enabled to view it.
> [This email address is being protected from spambots. You need JavaScript enabled to view it.] On Behalf Of Philip
> Lardner
> Sent: 28 September 2011 16:25
> To: This email address is being protected from spambots. You need JavaScript enabled to view it.
> Subject: RE: [Carbondragonbuildersandpilots] Re: Wing calculations
>
>
>
>
>
> Hi Folks,
>
> I've uploaded another few pages of calculations (Page-20 to Page-23 in the
> 'Phil Lardner' files directory) covering the rib layout and stress analysis.
> I've used the root rib as a worked example and will upload the numbers for
> the other ribs when I get them finished.
>
> I discovered a few more numerical typos in Jim Marske's text - confirmed by
> him. The text could also be a little clearer when describing how the rib
> panel centroids are arrived at. I mistakenly used the formula on pg D-1 of
> Marske's manual to calculate both centroids and got answers different to the
> examples in the text. It took me a while to discover my error - the
> centroids are being measured left and right from the spar location and not
> just from the left as on pg. D-1 - hence my drawing on Page-21 showing the
> graphical method of finding the centroids!
>
> Comments welcome...
>
> Phil.