That so few Graphlite strips were needed is a testament to the
incredible strength of this material, and to the huge contribution of
having such a thick wing. Bending stiffness scales with the cube of
the depth, so a little extra depth adds a lot of stiffness.

The 15m wing for my HP-24 sailplane design has 28 strips at the root,
and it deflected 47" at 4.4g:

hpaircraft.com/hp-24/update_10_dec_11.htm

Of course, its wing is less than 5" deep at its thickest point, and it
has a gross weight of around 825 lbs.

Thanks, Bob K.

> I built the leading edges using two layers of 284 carbon twill
> fabric 5.7 oz, laid up at 45 degrees.I didn't vacuum bag. Using Jim
> Marske's book I calculated that only 3 rods were required for the
> caps but I added another in case I decide to add some power down the
> road. I think the prototype deflected over 20 inches during the
> load test. Mine deflected a little over 14 inches.
>
>
>
> ________________________________
> From: ekolbs <This email address is being protected from spambots. You need JavaScript enabled to view it.>
> To: This email address is being protected from spambots. You need JavaScript enabled to view it.
> Sent: Tuesday, October 23, 2012 11:17 PM
> Subject: [Ultralight_Soaring] Re: carbon dragon
>
>
> Rick, thanks for sharing, we all appreciate it. I am curious what
> you used for the D cell skin, what type of cloth, weight/oz, how
> many layers, did you vacuum bag etc. I am really surprised that 4
> carbon rods can cary that load with that span with so (relatively)
> little deflection. I guess I have been way over designing my spar
> caps. Any other design specifics would be appreciated by the group
> from someone that has actually built (not just on paper). So thanks
> again!
> Mark
>
> --- In mailto:Ultralight_Soaring%40yahoogroups.com, Rick Mullins
> <flyndude@...> wrote:
>>
>> I did the wing load test over the weekend. I loaded almost 1500 lbs
>> on the wings which is the equivalent of 6Gs. Everything returned
>> to normal after the load was removed. I was expecting some ugly
>> noises during the test but other than "bonks" when the leading
>> edge oil-canned, and a crap-the-pants "bang" when a screw in the
>> test fixture sheared it was thankfully quiet and uneventful.
>> Â
>> I uploaded a couple of pictures of the test.
>>
>> Â
>>
>> ________________________________
>> From: ekolbs <ekolbs@...>
>> To: mailto:Ultralight_Soaring%40yahoogroups.com
>> Sent: Monday, September 10, 2012 10:35 PM
>> Subject: [Ultralight_Soaring] Re: carbon dragon
>>
>>
>> Â
>> Any updates? Really interested to hear about results of load
>> testing. Thanks in advance!
>>
>> --- In mailto:Ultralight_Soaring%40yahoogroups.com, "ekolbs"
>> <ekolbs@> wrote:
>> >
>> > Wow, very impressive. I just had to reply quickly and say looks
>> great and thanks for promptly sharing! I'm anxious to follow you
>> progress. Mark
>> >
>> > --- In mailto:Ultralight_Soaring%40yahoogroups.com, Rick Mullins
>> <flyndude@> wrote:
>> > >
>> > > I created a new folder called Carbon Dragon and uploaded some
>> pictures of build my spar, wing, and a current photo of the project
>> > >
>> > >
>> > > ________________________________
>> > > From: ekolbs <ekolbs@>
>> > > To: mailto:Ultralight_Soaring%40yahoogroups.com
>> > > Sent: Tuesday, May 29, 2012 6:24 PM
>> > > Subject: [Ultralight_Soaring] Re: carbon dragon
>> > >
>> > >
>> > > Ã?Â
>> > > Sounds great Rick. Any more details and pictures you could post
>> to the photos section would be appreciated by many.
>> > > Mark
>> > >
>> > > --- In mailto:Ultralight_Soaring%40yahoogroups.com, Rick
>> Mullins <flyndude@> wrote:
>> > > >
>> > > > Yes, you use the carbon rods in the spar caps rather than
>> carbon tows the plans call for. The shear web isÃ?â??Ã? 7725
>> fiberglass cloth like the Monarch.
>> > > >
>> > > > Jim's composites manual is great. Lots of good information.
>> > > >
>> > > >
>> > > > ________________________________
>> > > > From: Michael McKeown <michael@>
>> > > > To: mailto:Ultralight_Soaring%40yahoogroups.com
>> > > > Sent: Tuesday, May 22, 2012 11:57 AM
>> > > > Subject: Re: [Ultralight_Soaring] Re: carbon dragon
>> > > >
>> > > >
>> > > > Ã?â??Ã?Â
>> > > > Do the varying length carbon rods make up the spar caps?
>> Ã?â??Ã? Ã?â??Ã?Â
>> > > > What is the shear web?
>> > > > I have just ordered the book.
>> > > > Michael
>> > > >
>> > > >
>> > > >
>> > > > On May 22, 2012, at 5:21 AM, Rick Mullins wrote:
>> > > >
>> > > > Ã?â??Ã?Â
>> > > > >
>> > > > >
>> > > > >My spar is almost an exact copy of the one Jim uses in his
>> Monarch. I used 4 of the .092x.220 carbon rods and divided my spar
>> into quarters. First rod full length, second 3/4, 3rd half way,
>> etc. I used the same number for both the top and bottom spar caps
>> for ease of construction.Ã?â??Ã? I made carbon barsÃ?â??Ã? from
>> about 35 layers of carbon cloth for the wing connectors. According
>> to Jims composite design book I only needed about 18 layers to
>> prevent tear out but 35 gave me the same thickness as the 4 stacked
>> carbon rods, and I would have the maximum surface area when I glued
>> it up for the load transfer. The wings connectors are the same as
>> in the plans. I have plenty of pictures if you are interested.
>> > > > >Ã?â??Ã?Â
>> > > > >I'm about 90% finished. All the major pieces are built and
>> I'm assembling them now. I am currently fitting the wings and
>> yesterday Ã?â??Ã? I think I ran into another discrepancy in the
>> plans. Jim apparently started with a 16 inch wide pod and later
>> went to 17.and not all the dimensions on the drawings are
>> consistent. The fittings on my pod are spaced too far apart to mate
>> properly with the wing fittings. It will be a couple more days
>> before it has wings now.
>> > > > >
>> > > > >From: ekolbs <ekolbs@>
>> > > > >To: mailto:Ultralight_Soaring%40yahoogroups.com
>> > > > >Sent: Monday, May 21, 2012 10:04 PM
>> > > > >Subject: [Ultralight_Soaring] Re: newbie
>> > > > >
>> > > > >
>> > > > >Ã?â??Ã?Â
>> > > > >Rick,
>> > > > >I too have CD plans and have long thought that the Marske
>> spar would be perfect. Would you share any details about the spar
>> geometry? How many of what size rods and how do taper the number
>> down as you progress outboard. How are you making you center
>> attachment, overlap or fittings with bolt top and bottom, as in
>> Jim's workshop manual? Really interested to hear from someone who
>> has actually built, not just on paper.
>> > > > >Thanks,
>> > > > >Mark
>> > > > >
>> > > > >--- In mailto:Ultralight_Soaring%40yahoogroups.com, Rick
>> Mullins <flyndude@> wrote:
>> > > > >>
>> > > > >> Welcome Claude.
>> > > > >> I'm building a Carbon Dragon and I used Jim Marske's spar
>> design in it. Simple, lightweight, and strong. Doesn't get any
>> better than that.
>> > > > >>
>> > > > >>
>> > > > >> ________________________________
>> > > > >> From: claude
>> > > > <claudebouzerand@>
>> > > > >> To: mailto:Ultralight_Soaring%40yahoogroups.com
>> > > > >> Sent: Monday, May 21, 2012 11:59 AM
>> > > > >> Subject: [Ultralight_Soaring] newbie
>> > > > >>
>> > > > >>
>> > > > >> Ã?Æ'ââ?¬Å¡Ã?â??Ã?Â
>> > > > >> Hi all,
>> > > > >>
>> > > > >> I am living in France and I plan to build a Mitchell wing
>> B10 (I have the plans) I had a Bright Star Swift SN 16 I sold 1
>> year ago because I hadn't place anough to store it and it was not
>> easy to foot lauch(too heavy) .I am aeronautical technician .I just
>> want to use Jim Marske method for the spar-I am waiting for his
>> book I ordered last week.Your group could provide me good ideas to
>> perform this project!
>> > > > >>
>> > > > >> Regards
>> > > > >>
>> > > > >> Claude