Steve Percifield

My Feedback: (14)

[quote]ORIGINAL: Eindecker_pilot


Well, at least you didn't get emotional about it.

I just refreshed myself on beam theory. The torsional stiffness of a beam is indeed directly proportional to the cross sectional area. Without doing a full box spar, one is leaving a lot of area out of the structure. It's all in the thickness of the airfoil that determines how much area you've got to work with. I think the diagonal braces can help too (there, there Paul, it's gonna be okay) if they maximize the area moment of inertia in bending. The diagonal braces are subject to bending when the wing itself is in torsion. WHAT???????

thanks guys,
Greg

Horsepoweraviation

My Feedback: (50)

[quote]ORIGINAL: Steve Percifield


Steve....Steve....Steve.....(can I call you Steve?)

Greg is refering to that time around a flag pole!

HPA

geezeraviation

My Feedback: (3)

Work, what's that Art? Nope! And I still say thats rude, hey Paul Ill never diss ya, if you're lookin that is.lol
Doc

John Cole

My Feedback: (4)

Greg, 'twisty' wing structure is perfectly fine as long as your flying wires are functional.

John

Steve Percifield

My Feedback: (14)

[quote]ORIGINAL: Horsepoweraviation

Eindecker_pilot

I took today off as a vacation day! The others?? I don't know.

Eindecker_pilot

Paul, don't worry I already built myself a spare wing panel. Just hope I got the correct side.

Eindecker_pilot

Thanks John. This plane will have the fully functional flying & landing wires, as well as the X bracing wires between the front & rear pairs of struts. These wing panels were twisty enough though that it was outiside my realm of experience, hence my question to the collective here. I think I will go ahead & do the shear webbing (since the plans call for it anyway) & see where it stands.

best regards,
Greg

Tmoth4

My Feedback: (1)

NO!! I recently retired!

Don't worry about the twistiness. My Gotha's wing are floppy and twisty until all the rigging is on, then it's really rigid. The Siemens has very thin wings and the top wing is twisty too but they also stiffen up considerably when the struts and wires are on. On my 1/3 scale DH-2 there are no spar webs and no diagonals either. The wings are a little twisty but not as much as the other two.

I don't think spar webbing does any good unles there is sheeting on the top and bottom LE back to the spar. Then you would have a "D" tube structure which doesn't twist.

Also, once the covering is on and tightened there won't be as much twisting.

Jim

Eindecker_pilot

Congrats on retirement Jim! We thought you built fast before....

geezeraviation

My Feedback: (3)

Yeah Mike, if he's really retired it's going to look like the aircraft rolling out of the Consolidated Plant in SOCAL during the Second war.
Doc

Tmoth4

My Feedback: (1)

Not necessarily. My wife has her own plans for a lot of my time. ("Honey do's!") [:'(]

Horsepoweraviation

My Feedback: (50)

Yeah.....yeah...."sigh".......
There is no real retirement is there Jim?
You will ALWAYS be working for "The Man" in one way or another ....your whole life[][]
Good news..... you probably have a better "benefits package" now than you did on your old job[X(]

HPA

Horsepoweraviation

My Feedback: (50)

and by the way, doesn't anybody work anymore?
[/quote]

Well, I can not comment on this because I am on my work computer and I dont want to incriminate myself incase my work computer gets confiscated.............



HPA

Eindecker_pilot

Okay guys, here's some more progress. Finished framing up the center section (although it's lacking a sanding job & the cap strips). I got the rest of the carbon rods cut to length & tested out the assembly of the top wing. It's getting bigger....

I also included some better photos showing the carbon rod, aluminum tube joining system. The 0.188" OD carbon rods & the 6mm K&S aluminum tube are a really good match, not sloppy but not too tight either.

Total dihedral is 2" from the bottom of each wing tip to horizontal.

best regards,
Greg

Tmoth4

My Feedback: (1)

Looks great, Greg!

Make sure you order twice as much rigging cable and end-fittings as you think you'll need! [X(]

Jim

Eindecker_pilot

Thanks Jim, good advice!

Eindecker_pilot

I've started on the lower wing center section. This one is a little different than the upper center section... it has dihedral braces that fit into slotted center ribs & a large open area where the fuselage nacelle will go.

The plans called for a lite ply dihedral brace in the front (which I've used as-is). To connect the rear spars, it called for a steel wire to be bent & glued into holes in lite-ply plates that would span the spars. This seemed like more work for less functionality (the steel wire would support tension, but wouldn't give me any bending support, plus it doesn't provide anything for me to glue wing mounting blocks to). So, I just made up a new lite-ply dihedral brace & attached it as shown to the spars. Most of the ribs are balsa, except for the outboard end ribs & the inner most center ribs.

On this sheet of the plans, I've encountered some significant distortion in the copy I had made. The chord length on the drawing is about 1/4" too short. No matter, the ribs are the right size & I'm just being sure to size everything to fit that (in other words, lay down the sparts to fit the ribs, don't lay down the spars to fit the drawing).

On the outboard ribs, there is a pocket into which I'll be epoxying dubro steel straps (later, not shown now). Those steel straps will be the fitting connections for the tail booms later on.

The fuselage nacelle walls will be slotted to accomodate these dihedral braces as well as wing bolt mounting blocks. I've not yet put the wing mounting blocks on this part of the lower center section. That will come later.

Sure would be cool if others were doing the 1/4 scale DH-2. [8D] This thing's coming along.

-Greg

John Cole

My Feedback: (4)

Greg, it's looking good! A DH-2 in quarter scale is a future project for me!!

John

Eindecker_pilot

Thanks for the feedback John. It's still pretty rough at this point. I've only sanded about half of the wing panels at this point. I sort of got into a groove of slapping down ribs & cap strips & wanted to keep going without stopping to sand. So, I still have that to do.

I finished the lower center section framing & installed my aluminum tube / carbon rod joining system for it. Same as the upper wing. The wings are coming out fairly light I think on weight.

The lower center section will be bolted to the bottom of the fuselage nacelle. This is not per the plan, but I saw John Cole's DH1a do it this way & that made more sense to me than what the these plans called for.

I've still not added any cross bracing or shear webbing yet. Part of this is due to laziness. By using a hardwood spar, I don't think I need any bending reinforcement. I'm tempted to leave out the shear webbing & cross braces & just rely on the rigging & struts to provide torsional stiffness (Per Jim's input, if twisty wing panels work for his Gotha & stiffen up with the rigging, it'll work for the DH2).

Paul, with regards to redundancy how does this sound? The whole structure is reliant on the rigging in the first place to carry flight loads so I've got to add redundancy there anyway. I"ll achieve that redundancy in the form of these features: doubled flying wires, JB weld the crimps after crimping, loctite the turnbuckle threads, safety wire the turnbuckles, and use double nuts on the strut fitting bolt.

-Greg

R/C Art

My Feedback: (38)

Greg

Good to see you making steady progress.
I'm liking your wing joinery system more each time I see it.

Can't say as much for all the redundancy stuff that's going on, but I suppose that comes with the Engineering degree, doesn't it.
I like the KISS thought process as well as the "less is more" approach, but hey, that's just me......(for me, being simple minded is easy!)

Keep it going! I'll try to get back in the groove with mine ....... (someday)

Art

Tmoth4

My Feedback: (1)

Greg,

Nice to see you're moving along on this! I had my 1/3 scale one all assembled and I did all the rigging. It was amazing how rigid the whole structure (including the booms) becomes when all the rigging is in place. BTW, I'm not doubling the flying wires. I figure with the two bays, it's strong enough with single wires. It sure feels strong enough!

I know it's sacrilege but I'm using 4-40 Dubro clevises and solder-on cable ends instead of turnbuckles. I don't want to go broke buying turnbuckles for this thing and I like the convenience of spring clevises for assembly and disassembly anyway. At the other ends of the cables I used the balsa USA nicopress system. I went back and wicked in a little solder on those for extra insurance.

I had to take it back apart for finishing and painting, and I haven't built the landing gear yet, or done the control cable runs and pulleys. The DH-2 is a complex airplane. It's going to be amazing to see it with all the rigging and control cables on it!

Jim

Eindecker_pilot

Thanks Art, I'm happy with the joining system too. It's just a lighter weight version of Alan Morgan's. I briefly considered using wooden dowels like on the pup (instead of carbon rod), but to get them to fit between the spars on an airfoil this thin, would have required a much smaller diameter dowel that would have been prone to breakage (not during flight but during handling accidents).

Eindecker_pilot

Hi Jim,
Thanks for the details on your hardware setup. I know what you mean about the cost of turnbuckles.... Proctor may open up an "Emerick Memorial Addition" to their turnbuckle factory to commemorate what I spent on those little darlings. I just really really like the way they look though. Did you use doubled flying wires on your Gotha? I can't remember. I assumed I would use doubled flying wires simply because that's what's worked on my 1/3 scale Pup, so that's my plan.

I got a chuckle when I read you also wanted to put some extra insurance on those crimps with the solder. My JB weld here is just a cold version of the same idea. I did that on my Pup too. Probably never need it but.... I'm also planning to use the 1/4 scale Balsa USA nicopress system.

You're right about the complexity... It's like a flying sailboat with all the rigging & pulleys!

Greg

Tmoth4

My Feedback: (1)

No double flying wires on the Gotha. The real one didn't appear to have them so I figured it was OK. Plus, that plane has so many bays in the wings, if a flying wires fails, the ones in the other bays are still there.

My Nieuport 28 has double wires and the Siemens has single wires but they are heavier cable.

I solder the crimped ends because I saw one that pulled loose on somebody's plane.

Eventually, I'm going to put turnbuckles on the Siemens because that one doesn't have a zillion wires like the DH-2 and Gotha.