Sethhunter

Hi Alan,
Definitely good points. Not an undercarraige to bang around. I'm not too worried about the machine screws because there is a big steel pin set in the fuselage that runs through the fitting into a dowel in the aluminum strut (you can see the pin in the sketch but not the photos). The pin should take much of the shear load at the fuselage/LG joint; the bolts just hold the gear on the pins. Also, the strap that runs under the nose from side to side is functional, as on the full scale, forming kind of a craddle to distribute landing loads more uniformly to the bulkhead inside. That leaves the aluminum itself - I share your concern and did epoxy dowels a couple inches long in each end to prevent buckling at the joints, but not all the way through - I may regret that! In a hard prang, it may buckle. Incidentally, I used fairly heavy walled tubing from McMaster Carr, not thin hobby-fairing tubing. It came round but I squeezed it down slightly to ovalize it a bit. I can't find a scrap to measure it up (it's in my notes somewhere) but I'd guess the wall thickness is at least .030 or .040", probably T6 hardness. Of course I was trying to save the weight of a lot of steel down there, and of course there's major bungy on the bottom. If it buckles, I'm hoping it saves the fuselage. If it buckles too easily, the next gear would be more traditional; steel wire with wood.

More to Vern's question, I'm a bit more worried the cup that's anchoring the drag wire turnbuckle might pull out in a rough wing-down landing - I did not destructively pull test that joint. If it becomes a problem, I'd drill back into the fuselage and pin the turnbuckle end deeper inside.

The comments are great - please keep them coming - I sure don't want to overlook problems or reconsider other design methods.

arspievack

Seth,
I never thought for a moment you hadn't thought this all out before construction.
I noticed the pin in the upper end of the strut and understand the basic design concept which is deciding where you want the damage to occur , i.e. easiest place to fix.
After hearing that you used heavier alum. tubing I 'm sure you picked the right materials for the various "give" sites.
I agree it's much easier to put on new strut tubing than repair the fuselage.

I never doubted you had it psyched from the start. What's your estimated final weight?
Onwards
alan

Sethhunter

Ah, but Alan you know the design process - a series of educated (or not) guesses. It's all sounds good in theory. We never know which are the really good ideas and which aren't until its flown a bunch. Brings to mind my favorite Otto Lilienthal saying (1890's): "To design a plane is noting. To build one is something. To fly one is everything."

I'm still hoping to come in around 20lb. I weighed the AZM spoked wheel kit at 1.75 lbs. 1.25 is in the tires alone. Ugh. I'd like to check out the German wheel company mentioned earlier on the site to see how much their wheels weigh. Haven't ruled out molding my own tires (always wanted to try that!)

Incidentally - the cowl vents and cable exit guides were molded from fiberglass using female silicon molds made over wooden plugs.

Radiator is coming along!

VNulk

Seth,

Thanks for the post - great pictures! It's fun to work out the design and execution of scale details, isn't it? I'll take some photos of the Roland fittings as soon as I'm a little further along - a bit slow going right now. Should I reply here or start a new thread?

Vern

VNulk

Seth,

I should have read this post first. When I flew my 1/4 scale Albatros, I built with fully functional rigging. (BIG MISTAKE - I've promised myself never build that way again as the plane took over 6 hours to install, tune, and safety wire all the rigging - result - the plane had, and still does need, to be transported to the field fully assembled.) All wires were 80#-test plastic-coated fishing leader and I relied upon the strength of un-altered Proctor turnbuckles. All swaging was performed with copper tubing crimped to round (as in full size) over aluminum thimbles. The fitting was hit with a drop of gap-filling CA for luck. Although I never did test the turnbuckles to destruction ( I couldn't afford to spare one at the time) they have so far been plenty tough for the job. Never have I broken or stripped one. When I did have a real hard landing, or even a flip onto the back, the wires occasionally parted but none of the fittings or structure was ever damanged. I may have deformed a thimble but you'd have to look real hard to see it. For that reason, I never considered beefing up the wire size as they're easily replaced.

As far as your cup anchors go, I'm working on my design right now that I think will solve my problem, perhaps yours as well. It employs shaping brass rod to the correct cup shape on one end. Drilling through the rod diagonally (to exit where the turnbuckle rod exits, and to fit the threaded rod of the turnbuckle, and a larger size hole just deep enough from the side of the rod below to bury the end of the turnbuckle rod. Elongate the small hole on the top of the rod (cup) just enough to suggest possible realignment of the threaded rod. All the tension is taken on the outside of the turnbuckle eye against the end of drilled larger dia. hole. The drilled out brass rod is cut to length and silver-soldered to a hole in a brass plate when just enough of the rod protrudes to resemble the cup. I can't imagine that I've described this well enough. I'll send sketches and photos ASAP.

Vern

Sethhunter

Hi Vern,
I follow exactly what you're describing (I think). I like the approach. One of my limitations is machining facilities. I don't have a lathe or mill, but have thought often about buying them. So far I've hobbled along with a broad set of woodworking machines and hand tools. But I can't chase threads or make complicated dies, etc. Dan Schmidt (Abufletcher posted pictures of his DIII.a earlier) built his wings to come off as a unit but I don't know the details. (Unfortunately his plane was badly damaged earlier this year due to a radio problem). I debated that approach and may regret having mine come off as panels. I'd like to believe I can tune up the 5 wires on each side without too much trouble (some jigs might help). I was also planning to use traditional tubes/rods at the root and some locking mechanism (like sailplane wings). My load calculations for wing bending is based on the spar design, not the rigging. To get there with thin wings I'll be using laminated wood/carbon (strip) spars; carbon for tension and the wood for buckling and shear. As I mentioned above, I do credit the rigging for helping the cabanes hold the top center section in place.

Your rigging work sounds incredible. Did you make your own thimbles or is there a source?
I'm not a forum expert but I would think your project deserves it's own thread!
A question on your design - have you considered ways to add mechanical strength to your soldered joint? I'm not familiar with the physical properties of silver solder (compared to lead solder), but I've generally tried to avoid relying on it solely for mechanical strength.
Looking forward to seeing some pictures!

arspievack

Seth, Vern
I guess I'd better get into this discussion because I've been in both situations. I built a 1/4 scale Baby Bullet using the rigging as the method of holding and controlling the wings in position. Big disaster. I had flown it many times at my field and had a jig to set up the wing incidences etc. and yes it took inordinate time to rig and de-rig, and then the big day comes at Rhinebeck and I set it all up as usual. BUT the day is very humid and the plane sits for hours before called to the flight line and once in the air I can tell the wings have warped beyond my ability to hold it with aelerons. It went into the seats in a spiral and I was lucky I could get it away from the crowd into an empty area.

My Pfalz I had done what Vern did. Buy a bigger car!!! (Wagon) because rigging and de-rigging that giant was not worth the time it took to get it ready to fly. So it had to be transported in one piece, and checked at the field after coming out of my cool dry basement into the "whatever" weather of the day.
If I built that at 1/4 or 1/3rd scale I'd have to buy a trailer for transport.

Guys, It isn't easy out there. And now you know why old guys like me are extinct. Everyone today builds fibreglass jets and avoids this. We WWI lovers like the old wood and wire stuff, but time may have passed us(me) by.
I'm staying tuned.
alan

VNulk

Hi Alan,

I hear you! My "bigger car" was a full-sized school bus I converted to a camper. Just can't hide the fact that it was a bus, although it looked more like a grey tank, but I finished it off pretty well inside and drove it for almost 10 years. (it became pretty well-known at Rhinebeck and at the Qualifiers) Best of all, the Albatros fit inside fully-rigged after removing the wheels. An option I'm now considering is to make the tail half of the fues a bolt-on to the forward section. It would then fit in an affordable trailer. Any projects from now, however, will have plug in wings. The Roland has carbon fiber/aluminum tubes from Gator that makes it very transportable and with some fiddling, will fit in my Element. But the wings don't have scale interior construction either and are very stiff on their own, minimizing the reliance on all rigging being as critically tuned to fly. In constrast, the true-to-scale construction of the Albatros upper wing flexed so much that if the wing was held by one end only, the far end would drop over 4 in. I only built the wing that way for personal satisfaction but noone else will ever see the detail except in construction photos, or of course, if I should plant it too hard into mother earth!

By the way Alan, we're not extinct, we just smell that way!

Later,

Vern

BobH

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Hey.. I don't smell to bad lol but I did manage to spend nearly 3 years on my WWI project. It was a labor of love.. most of the time. I'm very happy with the results and I even get to fly it.. pretty cool!

VNulk

Alright, I'm sorry. I do have a question for other veteran builders though. When do these exciting new scale projects that we take on, take less than 3 three years?? At this pace, I may have only a couple more to go!

So Bob, what projects have you taken on?

arspievack

They take less than 3 years when you're retired ( or filthy rich) and don't need to work everyday.
alan

VNulk

I'm dead meat!

VNulk

Seth,

I did as you suggested and opened a new thread listed as Roland C.II construction details. There I posted a sketch (boy they come out badly don't they - I'll have to work on that!) about the cup rigging anchor we discussed earlier. It may help if you have any apprehensions about the deformed plate version. Who knows, it may be tough enough but I never tested mine on the static model.

In any of your work, as I stated there, silver solder can be a great help where you need strength in brass fabrications as the joint becomes stronger than the base metal. Lead solder joints are for very light loads and appearances only and can be subject to flexing and vibration failures.

I hope this helps - keep up the good work!

Vern

tommyp

My Feedback: (1)

Hi all,
I’m glad to see that there has been recent activity on this thread and I’m very happy that Alan Spievack has joined in on the conversation! He’s the one who got me thinking about building an R/C model of the Pfalz when I was just a kid. I was 6 in 1971, when that famous issue of Flying Models (June 1971) featuring Alan’s Pfalz came out. It has been kicking around in my house all along. I knew that one day I’d build an RC version, and 20 years later in 1991 I did build a Pfalz in 1/5 scale. I was so pleased with how that model flew that I ended up building another in ¼-scale in’99… that one flew even better, so thanks very much for your inspiration Mr. Spievak!

Here’s a scan of the worn out cover of my 06/71 issue of Flying Models:
http://i6.photobucket.com/albums/y23...t11/FM0671.jpg

I also recall having, and being very impressed with the cover photo from the Feb. 1979 issue of Model Builder magazine but can’t seem to find it in my magazine collection at the moment. I did find a scan of it on ebay though, so here it is for those who may not have seen it. To the best of my recollection, it was built by Bob Haight, but I could be wrong (please don’t hesitate to correct me on that). This issue further inspired me to one day have a scale Pfalz model and a beautiful girlfriend as well…Oh well…at least I have a scale Pfalz model…
http://i6.photobucket.com/albums/y23...t11/MB0279.jpg

Many topics have been touched upon since I last visited. I thought I’d mention something about my use of solid sheet balsa tail surfaces. My ¼-scale Pfalz rudder is made from 1/8� sheet balsa with dummy ribs on either side, and a hardwood leading edge. I’ve smashed that thing dozens of times over the years and I have to say it has fared very well, even with all of my abuse. The Pfalz is actually very easy to land, but at first I had too much nose weight in place, making it difficult to flare out for landing, so it generally ended up on its back (yes Seth…that radiator tank comes off every time!) I had many dead-stick landings too, which resulted in upside down landings when I couldn’t get my Moki 1.8 running properly.

The cause of that problem was that I made an opening in the sheet balsa nose for the carb opening. I didn’t want to put a non-scale hole in my nose, but had no choice as the carb sat just below the back surface of the cowling (1/8" sheet balsa). I made the hole the same diameter as the carb opening and the engine ran terribly while in the air…on the ground it seemed okay. Finally, Mike Gross from my RC club suggested that I enlarge the opening in the sheet balsa to allow a more proper flow of air into the carb without disturbance from what was essentially a deeper venturi than the engine was designed to run with. That made matters much better. I also had been flying without a muffler (even on a ¼-scale model it is hard to squeeze a muffler in that skinny nose), and a lack of muffler back pressure may have also played a role in the engine not performing very well. I plan to make a custom muffler for it before i fly it again! It sounds absolutely awful without a muffler and it’s actually embarrassing to fly something that obnoxiously loud.

Off the top of my head, the ¼-scale version weighs in around 25 lbs and has a 94� span. I weighed the fuselage ready to fly (no fuel) and it was 18 lbs. I have the solid neoprene tires with my own home-made plywood rims…they weigh a ton! I think I probably still have too much nose weight in place, but I will say that the Pfalz is just a great flying model…it handles the wind better than any WWI model I’ve ever had, and it has power to spare with the Moki in place. When the engine is running right it is a real pleasure to fly.

My 1/5-scale version weighs around 14 lbs with a 74� span. It also has solid rubber tires and plywood rims. It has an old OS 120FS engine in place. I used to fly that without a muffler too, and it performed a little better before I added the muffler. After the addition of the muffler, the engine ran more reliably and sounded better, but it lost a bit of power. As I understand it the newer 120s have more power than the older ones and performance would benefit from that (but my bank account wouldn’t). Still overall, it is a very nice flying model. Maybe shaving a pound or so off would help. It was repainted a few years ago, so the weight of the second paint job, plus repairs over the years have added up.

Getting back to simplified structures, I really admire the work that Seth is putting into his Pfalz…it is truly a masterpiece! I generally try to simplify construction and just shoot for scale outlines on my models. This makes them quicker to build and slightly less painful when I wreck them! It may also make them easier to repair. Manyyears ago I built a 1/5 Albatros D.Va. I eventually piled it up into a ball, but because the fuselage was sheet balsa, it was easy to build a new forward half of a fuselage and splice it in place. I'd think that if it had been all hardwood with thin ply panels it would have been a lot tougher to fix.

I also think that some of the kit manufacturers may be missing the boat in not using more accurate scale outlines when designing sport-scale models. Likewise, using scale outlines, but not simplifying construction to allow the average modeler to build them may also result in decreased sales for a kit manufacturer as I think some model builders may be intimidated by intricate construction that could be simplified with no noticeable difference on the scale appearance of the finished product.

I’ve done some static judging (outlines) at my club’s local scale contests over the past few years, and I’ve seen some beautifully built and finished models made from kits and plans that suffered low static scores because the outlines were simply way out of scale. It seems that some modelers tend to think when they buy a scale kit that the outlines should be reasonably scale, which is a reasonable assumption to make. I’d like to see a company like Balsa USA come out with a kit of a Sopwith Pup or maybe a Bristol Scout that has accurate scale outlines and features simplified construction…I’d be willing to bet that it would fly just as good as a sport version with non-scale outlines. Even using scale outlines with non-scale airfoils would at least enable more people to get somewhat decent static scores in scale contests. Several members of my club have BUSA WWI models and they all fly beautifully…most also seem to land just as bad as WWI models w/scale landing gear, so why even bother to make the LG out-of-scale (shortened gear, wider track) if there is little to no benefit in doing so?

I started building a BUSA Fokker D.VIII and found that the shape of the rudder and fin didn’t match the 3-view drawings I had, so I enlarged my scale drawings only to find that the area of the scale surfaces was very similar to that of the non-scale outline. Also the depth of the fuselage and width of the fuselage at the tail were off. I tend to think that these changes should not make any difference in the flying characteristics, so I’m going to build it with closer-to-scale outlines to see if the performance will be affected. There are a few BUSA D.VIIIs in my club, so it should be easy to compare mine against a stock built kit. Now all I have to do is finish it!

Well, I got off track a little here…I’d just like to say that this is not a complaint about BUSA…I think what they are doing is magnificent! I’d just like to see them lean a little more toward scale outlines with their designs so builders of their models can use them to more successfully compete in scale competitions. I want to see companies like BUSA and Proctor and GTM thrive so we can all get to see more WWI models flying at scale events!

Seth…keep up the great work!
Alan…are you going to the Rhinebeck model meet? I should be at the WWI Aero booth on Saturday if you should happen to go.

Anyone else who is going to Rhinebeck, please drop by and say hello!

Best regards,
Tom P.

Dai Phan

My Feedback: (2)

Hi all,

Would making the vertical and horizontal stabs flat look awful on this bird? How about flying characteristics if these are made this way? DP

arspievack

Dai,
Sorry I continue to be slow. I've drawn th pictures you need and will e-mail to you. Promise.
Answer: No flat surfaces will look fine, Both the rudder and the elevators on the real plane WERE flat. They were made from tubing and that was constant cord.
The verticle and horizontal stablizers had a slight taper but would only be picked up by a knowledgable judge in a top level scale contest.
If you're not aiming for that level of competition you can make them flat and no one will pick it up.
alan

abufletcher

I'm not sure I agree with this. From the drawings I've seen, while the horitzontal stab on the Pfalz was not quite as thick as the Albatros tail, it did have a noticeable negative airfoil. Of course "noticeable" is a relative terms and Alan's right that almost no one will notice if you just build a flat stab. The vertical fin, however, was integral with the fuse and a flat fin would be much more noticeable.

The rudder and elevator were, as Alan states completely flat.

arspievack

Abu,
You're quite right about the negative airfoil for the Horizontal stab. I had written a note to Dai about that and have a drawing to show it which I'm going to send.
The vertical stab had a slight symterical airfoil shape to it and would look a little strange if it were totally flat. I was trying to make it easy for Dai who as best I can tell doesn'tlike to invent his own techniques or drawings and is having this plane cut by a kit "cutter".
ars

Sethhunter

Tom, great to hear from you. Thanks for the additional information about your Pfalz.

Abufletcher/Alan; Are you sure the movable rudder and elevator were flat? Several sources, including German factory sketches, show pronounced taper in the elevator. The sketchs in Datafile 21 also show the rudder as triangular tubular sections. I agree with the comments on flat being fine for standoff scale, but have contrary information on the actual original construction. What source are you referencing?

abufletcher

Seth, I just checked on that famous photo of the striped down Pfalz in the Pfalz Aircraft book and you're right that the elevator section was clearly "triangular." You can see the wedge shaped ribs (wood? metal?) quite clearly. The rudder does seem to be entirely flat.

Alan, I think the problem here is that we're discussing several different levels of scale modeling all at the same time. A "flat" stab and elevator (with perhaps a bit of sanding) would be just fine on a sport scale model.

arspievack

Group.
Challanged as I was by you guys, and working from my memory (always a risky approach) I went back and looked at the sources and here-by correct my weak memory . Agreed: the elevator was triangular and the rudder flat. I stand corrected and next time you ask me , remind me not to do it by memory.

Altzheimer

Dai Phan

My Feedback: (2)

Alan,

Are you sure your Pfalz flew ? I am freaking out now... Where did I put my Valium? DP

abufletcher

Dai, the thing to remember here is that you'll need to decide what level of scale-ness YOU want out of YOUR model. No one else can (or should) decided that for you. Seth has made the choice to try to produce a miniature Pfalz replica. Neither Alan or Tom's plans are designed to do that. Plans allow you to decide for yourself how far you want to go.

Historically, we all seem to agree that the Pfalz (the original) had a tapered cross section to the elevator. Whether you decide to build your model of the Pfalz like this is up to you.

arspievack

Dai,
My Pfalz flew more than 350 flights and won many contests, and was written up in an article so people like you could use it and get pleasure out of making one like it or better.
What we're all trying to say is that you don't have to build an exact replica in order to get "your" version to fly. Experienced modelers know how to get a model to fly.
Trying to build an exact replica is a lot more research and work. If
you do a good job it will also fly. How well depends mostly on size but also attention to detail, like weight, balance, wing loading etc, etc.
We're all saying the same thing. Build to your level of comfort. Pay attention to good flight principle dynamics and you will end up a happy "flying " modeler.
here to help
alan

Dai Phan

My Feedback: (2)

Hi all,

I know that Alan's Pfalz flew over 350 flights and was retired in "full military honors" as it was said in the article. I have been in contact with my kit cutter and the cutting has commenced since yesterday! I am going to make it as scale as possible to my best ability. No doubt the vertical stab has to be airfoiled shape since it blends in with the fuse. A flat vertical stab would look awful. It is very possible that I can start building it sooner than Oct 1st. I am so honored to have many of the world's finest scale designers help me in this project. I wish Alan can give me an autograph on my Pfalz when it is done. Thank you all. DP