Azzir325

I won this Dumas DH 4 kit at the 2012 Biplane Bash in Farmington, Ct. Even though it is just a

little (35 inch wingspan) park flyer 3 channel model, when I looked over the box contents it

was a bit intimidating, but hey, I can do this. I think...

There was a build manual and full size plans to build on. An inventory revealed no short parts

and no shortage of 1/16th by 24 inch long balsa sticks-a bundle thicker then my thumb! Not to

mention piles of other "long wood" as well as five or six sheets of laser cut ribs and parts. All

this for a little park flyer! What have I gotten myself into?

Reading the build manual, I found that the first steps involved doing something I had NEVER

done (laminating and bending balsa) before, using building supplies (something called "artist's

foam board) I did not have on hand. So I did what any self respecting modeler would do in the

same situation: I skipped ahead to the next step, which was building the wings. I proceeded to

lay out the plans, pin down the leading edge (3/16th by 3/8th balsa-future step:"trim or sand off

everything that is NOT leading edge! Where is my dust mask?) and trailing edge, and then start

cutting those 1/16th sq balsa sticks down into "rib bottoms." Yes, it seems each rib has to have

a separate bottom piece to be glued to.

Next we add the spars and the ribs. The plans say to glue them in place, then glue the wingtips

in place (those pesky laminated foam board formed wingtips!). But wait! What about the

washout? The plans call for raising the trailing edges 1/16th at each corner, but they don't tell

you how or when to do it, so I decided to do it as I build the wing by gluing the wingtips in

place BEFORE I glue the ribs in place, then raising the trailing edge off the building board with

a spacer and then as the ribs are glued, the washout will be fixed. At least, that's my theory.

So now I am stuck until I can manufacture laminated, bent around a form balsa wingtips so I

ask at an art supply store for "artists foam board" in 3/16th thickness and am sold a sheet of

foam core sign board. What do you know? If the plans called for foam core at least I would

have known what they were talking about! I cut out the paper patterns and trace them on the

foam board, then cut out the forms using a hobby knife. So far, so good. I have to do one

rudder, two stabilizer halves and FOUR wingtips! Well, long story short, amazingly it worked

out pretty good. I used warm water to soften the balsa and tape and rubber bands to hold it on

the forms, gluing the laminations together with Elmer's white glue. and two of the wingtips are

actually glued onto the wing! Progress!

guamflyer

keep going man, i was always interested in that plane. Pat Trittle is an excellent designer. looked at alot of his stuff.

SLOPE FAST - SOAR DEEP

guamflyer

Zor

Azzir325,

Looking at your pictures, you are doing marvelously.

You will be so proud of having built your own plane.

Zor

Azzir325

Thanks Zor and Guamflyer for your words of encouragement. I have continued along my plan and will soon have the wing halves off the board. I'm gluing the ribs down in sequence, front (leading) edge first, followed by the spar connection to be followed by the trailing edge and using a long straight edge on top to make sure they are all flat to the plan. After that, they come off the board so I can build the center sections and then glue the wings to the centers with the appropriate dihedral. No pics now as there is really nothing new to see. I will take some pics when the wings are completed and I start on the fuse.
Rick

Zor

Rick,

Suggest you do not forget to double glue with aliphatic glue and create fillets for all joints to considerably increase the binding areas.

You will be happy to have minimum damages in the event of a crash.

Zor

Azzir325

Thanks for your suggestion, I'm on it. I used the white glue on the laminations because I was working with wet wood. So far, the rest of the build is going well with thin and medium CA plus accelerator, applied liberally. The rib trailing edges are designed with minimal contact to the actual trailing edge of the wing, but I made them work, and this morning took the wing sections off the board in prep for shaping and sanding. The wing center sections are next to build on the board and then the outer wing panels are joined to them with dihedral. Once I have two whole wings, on to the fuse and tail feathers!
Rick

Azzir325

I spent about an hour at the build today and got both center sections framed up on the board. The wing panels will need a lot of sanding/trimming on the leading edge, then shaping to meet the center sections at the right angle. Once that is done, I will have 2 complete wings save for the covering. They are very light weight and delicate.

Azzir325

It's Saturday and I am not going anywhere, so I kept busy at the build. The task accomplished today was to finish the wings. I used my hobby knife to trim the leading edges down to rough shape, then switched to sanding sponges. The hardest thing about the job is that due to the delicate nature of the built wings, it is hard to hold them and sand on them without breaking them! I have to admit to popping a few pieces loose here and there. A little CA and good as new.

The center sections have not been sanded yet. They are built on the board and as the outer wing panels have to be glued to them I will sand them after the glue dries. I opted to make these joints with white glue so I could wet fit them, adjust them, and make sure I had the dihedral set correctly before the glue set up. My sanding sponges were exactly one inch thick, so I set them under the wing tips at the prescribed location, and put a small amount of weight on the wingtips to assure they dry as true as possible, but not so much weight as to squash the sponges down. I will let them dry overnight, and perhaps by tomorrow I will get to start to lay up the fuselage. The only thing left to glue onto the wings are the 1/16th square balsa spars, and they will go on with CA so that will be quick.

Azzir325

OK so we continue to slog along, and I mean slog. This thing is technical and the build manual and pictures could sure be better! But the wings are off the board and sanded to final shape, so I moved on to the fuselage, and it is taking shape nicely. I am still skipping steps here and there because I haven't made any decisions on power yet, so I need to NOT clog up the access to the firewall. Trittle designed it around a stick mount geared brushed GWS motor of a size I do not have, so I will be shopping. The dilemma is the guys who give you good advice on their motors also charge you like the motors are made of solid gold, but the guys who sell the right brushless motor for 10 dollars don't do a very good job of helping you pick the right one. Ce la vie. I'll figure it out. Plenty to keep me busy in the meantime. Here's a few pics of the fuse.

ARUP

You sure are doing a nice job!

Azzir325

Darn this little model is technical! Seems like I have been building for weeks. Wait! That's right! I have been building for weeks. OK, so not full time, but hey...

At this point, all of the main structures are built. I am satisfied and hopeful that in a few more weeks I will have this little biplane flyable. Make no mistake, there is still a ton of work to do. I have a rimfire brushless motor from another model that I am not flying and plan to sell/give away, one of those Great Planes VFO's. I'm pretty sure this motor will be plenty of power for the DH 4. Now all I have to do is design and install a proper mounting system for it. Along the way, there are servo mounts to be built and servos to install, with pushrods. And after all of THAT fun, we still get to cover this little beauty! It came with blue and yellow tissue and I plan to apply it "old school" with thinned Elmer's glue on the framework and dampened tissue laid on it. After it dries and tightens up, a coat of shaker can clear to fill in the pores and give the decals something to grip. Of course, most of the above comes before the airframe is final glued together.
Rick

Zor

Rick,

Just absolutely beautiful; the types of models we used to build in the late 1940s and early 1950s.

Thanks for the memories Rick.

Zor

Azzir325

Thanks, Zor. I doubt in the forties and fifties they had much laser cutting, but I get the drift, and have a much greater appreciation for ARF's!
Rick

Azzir325

So yesterday and today (Christmas Eve) I have been busy designing and building. Got the servos installed. That was pretty straightforward and according to plans. The power system was another story because I used a small outrunner brushless Rimfire so had to manufacture my own mount after I figured out how to mount the radiator/cowl and got the right distance for the prop shaft. It was a matter of trial and error, fitting and refitting but I got it lined up and solidly mounted. It's test run and now the model is ready to cover. Which brings the next little problem which is they packed too much blue tissue and not enough yellow. I think they got it reversed, since the wings and tail feathers are yellow and only the fuse is supposed to be blue.

Guess my DH 4 is going to be reverse color.

Merry Christmas!
Rick

wphilb

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Rick,

Azzir325

Thanks, Whit! Actually, I have always been up there, but I'm a lazy bones. My WW 1 contingent is pretty healthy even if they are ARF's, with the Camel, the D 7 and the DR 1, all three of which have flown at Delaware in the gaggle as well as on the regular flight line.

You may know I have a full kit coming from Precision Cut for Roy Vaillencourt's Stinson L 5. I'm hopeful about having it at WOD this year. I sure hope you can make it!

Merry Christmas and Happy New Year to you, Amy, Jane, Mary and Shailer (sp?)!
Rick

wphilb

My Feedback: (10)

I look forward to seeing a thread on it. I assume it will be in USMC colors! 

Azzir325

Actually, there is a story with pictures of the Grasshopper's Glory Flight in Flight Journal magazine from June 2011. If the stars align, my plan is to recreate the plane and flight of Lt. J. D. White with surrendered Japanese general Gyosaku Morozumi of September 8, 1945. USAAC, 25th Liason Squadron, aka the Guinea Short Lines. I think we already got enough of those Jarhead Corsairs etc flitting around, don't you?

Maybe I'll take a run at new club wiseacre and give our news editor some competition...
Rick

Azzir325

OK, back to relevant stuff! Plus the view out my kitchen window.

12/29/2012
After thinking on it for a week, and realizing that unlike Joda I can not yet think things into reality, I started the covering job. As I mentioned, I have 2 sheets of blue and one sheet of yellow, which by the way is exactly what the inventory specifies. The picture on the box shows the wings, top and bottom, as well as the tailfeathers, covered in yellow. Only the fuse is in blue. Well, you don't have to be an aeronautical engineer to figure out that there ain't enough yellow to do the whole job. I decided to try to get the wing TOPS and the tailfeathers done in yellow, using the blue for the rest. I will yellow the tail first, followed by the tops of the top wings, and if there is enough then the tops of the bottom wings. Everything else then will be blue.

I started by doing the bottom of the fuse. There are 2 pieces, a front piece and the rear fuse. I don't think the tissue that came with the kit is actually silkspan, so instead of dampening it as I apply it, I am putting it on dry after I apply thinned Elmer's glue to the wood frame work. So far I have done the fuse pieces, the wing center section bottoms, and half of the rudder. I am going to give it plenty of time to dry, then attempt to shrink it with a spritz of water and trim it to size. I have a 4 day weekend (Happy New Year! Yippee!) so who knows how much I can get done.

Been working on it on and off all day. Never bothered to get out of my pajamas. TMI? Sorry. BUT, I have tissue on the bottoms of both wings, on the bottom and sides of the fuse, and both side of both stabilizers. I might have rushed it a bit, but I have pretty low standards. It all looks fairly tight, and that is before any water shrinking, which I will do either tomorrow or after I finish all of the covering.

wphilb

My Feedback: (10)

Rick,

Azzir325

Thanks for the info, Whit. I think I've heard of that "infernalnet" thingy you mention, but it's frozen here. Another thing is, if I was to buy more yellow tissue then what would I do with all the left over blue? You know, like good airplane mechanics everywhere, I use what I have on hand.

As for the white stuff, ve haf vays to deal mit dat shtuf, und ve shtill fly ze luft, yah.
Rick

Azzir325

January 1, 2013 Happy New Year!

Having kept at it on the 30th and 31st of December, today, the first day of the new year, I present for your delictation, the first ever appearance in person of the (MY) Pat Trittle designed Dumas DH 4 in something like it's projected final appearance. That is, the pieces are all stuck together and it looks like an airplane! Yippee!

Don't misunderstand. The plane is far from completed. In fact, I am now at the point in the assembly manual, such that it is, calls "final assembly." Interestingly, they fail to mention that if you glue everything together the way it is built, neither the rudder nor the elevator will work. Seems that forgot to engineer in a little bit of clearance for the control surfaces to move thru. So this will require an bit of cutting and glueing of new parts in place to keep the vertical stab from falling apart and to keep the rear of the fuse from popping open. Well, that's modeling!

Zor

Very nice and Happy New Year to you also.

Zor

Azzir325

Thank you, Zor.

Azzir325

January 6, 2013

So on New Years day I apparently came down with a cold and have been pretty miserable since. Not sick enough to stay home from work (DAMN!) but sick enough to not do much work on the model. Still, some progress is being made. After cutting the rudder and aft end of the fuse to allow the control surfaces to move, I had to insert new pieces of wood in places to hold things together. "Final assembly" instructions are pretty broad, basically "glue the model together then you're done." But at least it's something. You have to glue the lower wing into the saddle and then the landing gear is added. To me, most of what is going on now seems pretty unlikely to hold together as the glue joints are minimal. But then, I'm more used to working with larger glow and gas planes, so maybe this is perfectly adequate. However, telling you to tie the gear into place with thread when the gear mount rail is completely enclosed inside the now covered wing, well, you get my point. BTW, I used copper wire and thick CA.

Also, there is very little to glue the horizontal stab to, and LESS to attach the vertical stab to. I added wood cross members under the horizontal and I added triangle stock to the rudder. I rubber banded 2 sanding blocks in place hoping they would keep the vertical square to the horizontal. It seems like it's sorta kinda maybe lined up. Although there IS a "wing alignment jig" for the top wing attachment (cut from that good old foam board, of course), this whole thing is going to be an "eyeball" type alignment with a total of TWELVE struts (8 interplane and 4 cabanes) to deal with and line up. As I flounder around this lobster of a build it'll be a mackeral if it flies!