My Fokker DVII Project

[jumpinjan]

Yeah, that would bring it up level to the rib, and then not pull the fabric.
Jan

[Jeff Brooks]

Udo,
Thanks for the input!
I see the wedged shaped wood on the fittings that you talk about, but I am not sure if this wood raises the fitting or just brackets it. Can you provide some input?

Here are a couple of pictures from Achim's wing.



Also, it is not pictured here, but is there a steel strap that wraps around the spar? I know there is on the fitting near the frame, but I am unsure about the one near the wing tips.

[franzkait]

you never get this fitting realy tight, ander loud ist will always move a little .So you have a small moving metal part sitting on top of the soft spar wood .You will create a breaking possibility.Original the spacer is made from hard wood , but you can also use birch plywood . And like Jan notice , with no spacer you pull the fabric down . Why Achims wings for example ? Why do you not look at original Fokker wings ?

from Thread , Help on plane type !
8. do not take any advice from people who never did build anything already flying .
11. do take advice from people with an engineer background .

[Von Writter]

Franzkait, if you can never seem to get the bracket tight, maybe the spacer was a wedge that was inserted after the fitting was installed to tighten it? Just wondering as it would do the trick and space the fitting at the same time.

[John McKenzie]

Hello Jeff , Just a small point in respect to your fitting shown as the lower photo of post # 1668 . The 2 upper lightening holes on the rear face of the rear spar fitting are overlapping into the bend area ....Although these will be 5mm farther away "after " you make the spar with the correct hard ply packing as Udo tells you .They will still be too close ,even after you have re-positioned them(by 5mm resp. to bend ) , for them to be drilled out to size before bending ...This can cause cracks to tend to develope from either side of the top of the inside of the lightening holes ,into the bend area , because of the now overstretched distorted portions on either side of the "mid point ", which in this case , has NOT followed around the curve with the rest of the metal due to the holes proximity to the bend .
If /when you have to have holes so close to bend areas , it is far better practice to first drill only " pilot " holes ,..Then do the bending , ..Then finaly drill the hole out to the correct size afterwards........This way , you will avoid the distortion around the hole near to the bend , and any potential problems that this can /might cause later .Regards John

[Maxim08]

Jeff,
Here's a picture of the lower wing interplane strut bracket from the Ottawa D VII.



The wings, as you know, were rebuilt by JD in the early 1970's. The bracket is shaped quite differently from Freeman's/Kiger's. The apparent gap is caused by the base of the socket under the strap.
While none of the Ottawa wings have any build up on the spar around the brackets, the Knowlton aircraft does. Never thought to measure something hidden by fabric, but you can feel them when lightly pressing on the leather reinforcing patch. No apparent depression or bulging in the fabric.
If the brackets are 2mm and the socket base is 2mm, that doesn't leave a lot of room for anything under the socket base for load spreading considering that the capstrips are 5mm in height.
FYI, the Knowlton lower wing is Albatross made and the Ottawa Fokker made. Differeent approaches by different builders?
Regards,
John

[Jeff Brooks]

Udo, John & John ... thanks for the input.

Udo, I only used Achim's photo because it was readily available ... not to start any controversy. I have seen plenty of photos of this part, but I was unable to determine if the fitting was raised. I did not know the wood under the plywood skin was a hard wood. I made mine with spruce spar stock.

John M, good eye on that bracket. I went home and looked at all the brackets, and that one is the only one like that. I will swap it out.

John W, as usual, your timing & input is perfect. thanks for the answer. I was worried I would have to plug those hole to re-drill new ones to move that fitting.

[TSJohnson]

Question for the engineers. Is the spacer under the interplane strut fitting meant to spread the load under the metal fitting and keep the wood fibers on the top surface ot the spar from being crushed?

[John McKenzie]

Hi , Answer is basicly , Yes ....Because of the lower compressive strength of spruce ACCROSS the grain . The main loads should not be too far off vertical , in the front elevation ,and so "tilting " of the bkt sideways should not present a problem ...It can easily be prevented at all with wedges on either side of the fitting ( relieved for the circular flange part ).In side view , loads can be a bit offset , but the fitting is 2mm thick and well supported on the spar sides .( Note that the original spar was Kiefer..White pine , which is a little harder and stronger in comp' accros grain )
It appears from John ( Maxim ) that maybe , only some D VII's used the hard wood facing anyway , although , without the drg. It could be possible that this is not a spacer as it appears (?), and may only be side wedges to steady the fitting ?!.
Regards John

[jumpinjan]

Originally Posted by TSJohnson

Question for the engineers.

The loads are on the bolts and the holes, not on top of the spars