DR-1 (Sands): Builders Group - Page 236

RobW · 27 September 2008, 04:52 AM

Quote:

Originally Posted by Dogtail2

That picture is not G-ATJM. It is John Day's recently built G-CDXR shown below. The pictures on your link are also incorrect.

Dang, I hate it when that happens...

CORVUS · 28 September 2008, 03:43 PM

Hi,

Can anyone say what type engine is in John Day's Triplane. It looks like a nice fit.

Lou

Never mind. It's a 145 Warner. They really do fit nicely.

tengew · 28 September 2008, 04:46 PM

out of all of the Dr.I's out there who's are closest to being like the originals

Maxim08 · 28 September 2008, 05:45 PM

Tengew,
Fred Murrin's.
Regards,
John

tengew · 28 September 2008, 08:09 PM

his is the only one flying or just plain the closest

Maxim08 · 29 September 2008, 05:21 PM

tengew
I believe that there are at least two other rotary powered around. Javier has one and so does Roger Freeman. Search the site for both.
Fred's is the only one that I have inspected up close and, while I have never seen a 'real' Dr1 to compare, I have spent quite a bit of time with two 'real' D VIIs.
The common point is enginering and building that makes sense. Simple, light, strong and to-the-point.
I have close association with 2 repro triplanes and 1 (and a bit) D VIIs. I have spect some time poking at the tripes in Omaka and they all make concessions or cut corners to make them (supposedly) easier to build, maintain and/or fly.
I nominated Fred's because that's the one I have looked at closely.
Regards,
John

Maxim08 · 29 September 2008, 05:25 PM

A few photos.

Regards,
John

CORVUS · 29 September 2008, 08:26 PM

I was looking at those photo's of the landing gear of the D-VIII in the Windsock Data file. For those of you who have this issue you can see what I mean on page 31.

I see a seam in the sheathing that is in the center of the "V" in the struts that runs the width of the gear wing. That means there's a layer of wood on top of the aluminum box. It would have to be flush with the rib cap strips and of the same contour. You can see the wood in the photo. If there are wood inserts on top of the box how do you think they secured the wood to the aluminum box ? They had to nail the sheathing into the wood and the nails are right on the edge of the seam which is on the center line of the wood. So the method of securing the wood to the aluminum might be ? Glued and screwed. Bevel headed counter sunk sheet metal screws ?

Sands shows the "X" brace guy wires being secured to a clip welded to the top of the steel box right in the middle of the "V" strut's. Right where the sheathing goes. The D-VIII factory drawings show that clip welded to the forward strut arm. Maybe that would be better.

Have you seen those two large diameter Aluminum tubes that run the width of the wing in the original gear wings ? One in the front and one in the back. The flight report for the Triplane says they serve as additional wing spars. I can see them only as a means of securing the 2 out board ribs. Not sure how that's done. No lightning holes in the ribs. Just those big round holes for those Aluminum tubes. I don't understand what purpose they serve if their not tied back into the main spar. They look like they float in the rib holes. About 2 inches from either face of the aluminum box.

You can also see in the photo that the ribs of the D-VIII wing are not uniformly spaced. Every other space appears to be different. Alternating dimension. Looks like there's maybe 8 ribs. The center to center dimension shown on the Flight Report Article between tires is 5'-3" and on the Factory drawing of the D-VIII it's 5'- 8". Whether or not the alternating rib spacing was duplicated in the Triplane is hard to say since the width's of the wing appear to be different.

Can't see any rib stringer's in the photo. They must have come loose when the sheathing was removed.

Sands has those bungee cord tubes spanning the full width. Not sure if the original did it that way. The Flight Report drawing of the Triplane does not show them as contiuous. Just welded to the steel box. Continuous looks strong and makes sence.

I'm not critizing the Sands drawings and his method. What he shows obviously works very good. Just throwing some stuff out into the ether that might be of interest.

Lou

tengew · 30 September 2008, 01:42 AM

thanks for the pics love that plane

Jeff Brooks · 30 September 2008, 06:42 AM

Quote:

Originally Posted by CORVUS

I was looking at those photo's of the landing gear of the D-VIII in the Windsock Data file. For those of you who have this issue you can see what I mean on page 31.

Have you seen those two large diameter Aluminum tubes that run the width of the wing in the original gear wings ? One in the front and one in the back. The flight report for the Triplane says they serve as additional wing spars. I can see them only as a means of securing the 2 out board ribs. Not sure how that's done. No lightning holes in the ribs. Just those big round holes for those Aluminum tubes. I don't understand what purpose they serve if their not tied back into the main spar. They look like they float in the rib holes. About 2 inches from either face of the aluminum box.

Lou

I had similar issues when making my landing gear.
I found that the two outside ribs are missing the support of the inner rectangular spar that holds the axle because of the cutout used to get at the shock cord. The skin of the axle wing is not enough to keep it rigid.

I believe the two tubes are there to add support to make the outside edges of the wing rigid. The skin kinda pushes the outside ribs outward, while the two aluminum tubes pull the rib inward. This tension creates the rigidity. The holes on the inner ribs are very snug so the tube does not move around and the ends are hammered over with a plastic hammer to create a lip.

There was a lengthy discussion about this on another thread. Posters provided photos looking for evidence that the tube may or may not have been removed after the LG was assembled.

Quote:

Originally Posted by CORVUS

Sands has those bungee cord tubes spanning the full width. Not sure if the original did it that way. The Flight Report drawing of the Triplane does not show them as contiuous. Just welded to the steel box. Continuous looks strong and makes sence.

Lou

The DR1 & DVII bungee cord tubes did not run all the way through the LG wing, and although the Sands method does seem stronger, it adds weight! Aircraft are a careful balance of strength vs. weight.
The practice of over building a plane to "make it stronger" has a diminishing returns on your investment. Making the landing gear stronger by beefing it up, adds to the gross weight, and makes for harder landings!