Ok, I have to post to this. Many years ago I worked for the King Gorilla (aka Satan) at a large manufacturing company. He was a VP and I was a manager over supervisors. Yes, he was a great manager for getting the numbers but, to list just a few of the highlights, here is what it cost:
1. He...
Alright, I have to put my two bits in.
Back in '91 I was going through the standard college placement service interview for an engineering job with a large US oil company. Times were tough then for engineers with a recession on and of mass layoffs. like any other prepared interviewee I was...
OK, This isn't a technical question but one that I am sure that we are struggling with. We, like everyone, are hiring new stressers everyday. I've been a stress engineer since '91. I was trained in the old Boeing way, find the grizzliest old stress guy you could, then shut-up and listen. In...
Sorry it's taken so long for me to respon. We gotta take some vacation sometime.
Anyway, I'm not sure either, I recieved an e-mail from this site warning about not giving out e-mail addresses.
Go figure? I can paste the text here, but without the graphics, it's pretty much useless. I...
I have an excellent bushing installation spec, drawings, and process description that I have used for years. I've found that when used, freeze fit bushings can be installed with light tapping and perfect fit every time.
I tried machinerys' handbook a few times and found the tolerances too...
Wairau,
Just a note on spinners. While it may not seem to be structural, some prop a/c have the spinner listed in the POH as "Required Equipment". Usually to allow for proper cooling of the engine.
What I am getting at is that while a spinner may not seem to be significant structure, you do...
Koopas,
You asked for ¢2,... well here it is....
First of all, I think you probably are correct in that Douglas has some sort of error in their formula. The stress group of the current Douglas owners (or ownees), use an Fbru based on 1.7e/D, >ON ORIGINAL NEW DESIGN<. This is/was to account...
Floorwax,
I know of a nifty little Mathcad application available on their website as shareware.
Its a little Mathcad file that takes a bitmap BMP and reads the pixcels to determine section properties. What you do is, you draw the section by hand or plot it full scale. Scan it in to a bmp and...
Well, This subject has probably been beaten to death, but here is another crack at it.
Take the case of a gouge in a skin panel (not too deep). To remove the gouge, you typically blend at a 30:1 ratio to restore most of the fatigue resistance properties. You might even possibly locally flap...
Try this,
"Handbook of Technical Writing", Third Ed., Charles T. Brusaw/Gerald J. Alred/ Walter E. Olin, St. Matins Press, New York, NY, ISBN: 0-312-35810-5.
I swear by it.
HSThompson
Pip,
I have seen this situation before and this may come as a shock.
I was involved in a case where we purchased cress material from a supplier who used a somewhat unethical yet perfectly legal manufacturing technique. Specifically, during the rolling or mill process of the sections and...
Rob,
I received your sketch. I and other fellow DER's reviewed both of the concepts you mentioned. We agree with you and disagree. Essentially both repair methods are not acceptable. In the no joggle case you are leaving the skin patch unsupported exposing it to differential bending along...
Ed and all,
I apologize for not responding sooner, recently had a death in the family and things are crazy.
Anyway, Yes I do have access to all the stress notes, test data, report, etc. since I am the OEM. (Note: This is an upper mid-sized business jet.)
To restate here: while the...
Actually guys, I think I have an inspiration of sorts...
I think I will analyze this as a circular cut-out with the diameter equal to the major axis of the ellipse.
My justification is two fold:
1. The direction of the ellipse major axis is parallel to the axial tension in the skin. This...
SparWeb,
No I wouldn't say an internal doubler is out of the quesiton, but I just don't believe it is necessary. The reason I justify that is tha the wing was tested to 160% of limit load. That being the critical case of upbending, which would give peak tension and shear flow around the skin...
For SparWeb:
Yeah, It looks about as elliptical as you can get.
I will be checking Green Niu for further information.
For aviat:
I fully understand what your saying. Unfortunately this is a rather new a/c, <400hrs. I am the stress guy that defines what the limits are and I need a...
Skin reinforcement / Ellipse Cut-out
I have monitored this forum for quite awhile and this is my first post so I will try to be as clear as possible.
Situation is:
I have a lower wing skin with a fuel bay cut-out shaped like an ellipse. It has an integral chem-milled cut-out reinforcement...
laXXX,
Try the HL48 - Protruding Head, A-286, 95ksi shear, cad-plate.
BTW that is just the basic pin. If you know the fastener code I could be more specific. (ie. BACC30? collar).
HST
york,
Ditto to jetmaker's comment. I might also add that since by definition c/t holes are meant to be a "tight" fit, adding primer will make fastener installation very difficult. I agree with, and often use, wet installation with primer or sealer as the situation requires.
