mulligan

I just looked at my drawing properties and learned that I've spent 175 hours editing my current project drawing... and I'm not even half way done! [&o]

I think I would have been better off not knowing. But just for giggles, what do you guys normally spend concocting a design?

ptulmer

My Feedback: (5)

Simple sticks or deltas-- about 40 hrs. Bigger or more complex like a scale plane...no more than 100 hrs.(in fits and spurts) Of course, I don't go above a .60 size design. What are you designing?

mulligan

1:7 scale C-47...

CoosBayLumber

My Feedback: (1)

Usually takes me a week or two, no matter what size. However, that also includes cutting the lawn, driving to the store, etc.

I must be missing something here too. I don't see any "How to" notes. No part numbers, no description on where to fit what. I do not see installations for radio equipment, how wing is to mount/dismount, etc.


Are you trying to learn the software at same time?



Wm.

BMatthews

And you're complaining?

I think that sounds not too bad for such a complex project. Let's not forget to take into account the head scratching. That can't really be included in the drawing time....

DICKEYBIRD

You guys actually finish a drawing? I find something to change on my plans no matter how many times I say I'm finished and look at them just "one more time."

mulligan

Wm, I am less than half done. There are servos in the tail, but because the drawing is so big (each fuselage section is over 9' long), you probably can't see them. I haven't even begun the wing yet. Basically, I'm done the tail feathers, the fuse formers, and the tail servo/linkage locations.

I don't know that I will add "how to" notes, as I'm designing this for myself, and you can bet I'm (too) familiar with every detail of this drawing and what the assembly intent is. It's a good idea- no, a necessity if you're making plans for others, but that's not my intent. And as dickeybird mentions, you can always tweak things, even after you're "finished."

I'm using AutoCAD 2000, and I've taught AutoCAD classes, so it's not clicking efficiency that's taking so long, it's just that it's a big project. I was just wondering how much time others have spent on similar projects.

dr_wogz

My Feedback: (3)

I find it very easy to get 'involved' with a design, and you can easily loose track of time!

One thing I have disdovered with engineering, is that there is really never enough time to do it right the first time, but you get all teh time you need to make the required (wanted) changes, once the design has been approved!

Depending on what I'm designing, can take a day, or it can take a few months. all depends.

And yes, head scratching, research, and fiddeling with teh printer shoudl all be included in the design time, that is, if you're getting paid. if not, enjoy!

CoosBayLumber

My Feedback: (1)

My thought here is that too much time is being devoted to maybe the wrong concept or detail. Many of us herein use what we have, adapt that software to meet our ideas, not the reverse. If you are familiar with most all the aspects of Acad, then there must be some problem in getting your ideas onto the page. The remainder of us already have the concept in our head, it is getting the software to interpret what we are thinking of. Then again, most folks who draw up model A/C plans tend to borrow or plagiarize off our predecessors. We may like how the wing goes on to the fuselage of a Comanche, How some designer controlled an elevator on a Hellcat and how the nacelle were mounted on a Heinkel. These ideas all then get set in one way or another into the project.

It is also of benefit to have a library file on known items such as glow engines, retractable landing gears, and radio equipment. Then you can swing these into place and move interior parts around to meet their mounting pads. It is helpfull to know where certain things just have to be before getting too far into the project and then backing up and revising everything again. Hardest thing for me has always been what to do with a muffler hanging out from the engine, or is the landing gear going to affect spar placements in the wing. If you steal a few ideas from prior designs, then you know what to do when it comes up for you.

As Dickeybird mentioned, you also will probably not build one prototype. Took me three to get the incidence down correctly on a recent model. Then two more prototypes to get it such that radio gear could easily be installed. Also it is no embarassment to quit for a while, take up another simplier project, tehn come back to the main effort.

Wm.

Mike James

Yep... William says it well.

Personally, I collect my references and do all the important exterior geometry first, then with that "frozen", continue on with details. The details might be a week's work, or a year's work, depending on how I feel about the project.

One thing I think we'll all agree on, is that CAD becomes easier and faster, the more you do it. Computers get faster, software gets better, and in most cases, we can upgrade our existing "libraries" of parts to fit the next software version. I'm having a great time using it, and like the 3D backup it provides to my paper (2D) drawings.

And... I love my Mac!

blw

My Feedback: (3)

Mike,

I'm using a Mac too- a new G5 dual processor. I'm interested in the software that you are using. The only thing that I'm using now is Swivel Pro 3D (very old version) and Alias Sketch. I could jump to Maya if I find the time. Any comments on your setup would be appreciated.


Barry

Mike James

For most of the modeling tasks discussed here, I have an uncoventional setup. I do all my final production drawings on vellum at this time, aided by 3-views and cross-sections from my CAD software, which is "Carrara Studio". (Runs on PC or Mac - See http://www.eovia.com ) If you need to produce "plans", including templates and parts outlines, AutoCad or something similar is probably a better choice, but for me, 3D is a visualization tool, and not "the end" of the process. All of my models are composite, so "builder's plans" are not required in the kit manufacturing process... only accurate drawings for producing the plugs, and certain assemblies.

Lots of examples of my useage of this software on my site, including a generic "CAD Tutorial", at http://www.nextcraft.com/rcdesignandbuilding.html

Have fun!

canadagoose

My Feedback: (2)

mulligan , take a look at my project here http://www3.telus.net/public/tjlewis.../Projects.html
I spent around 2 months drawing which was off and on, my guess of actual computer time would be around 75-90 hrs.This was my first real CAD project. The actual building took 3 1/2 months off and on and as usual when i build from plans i didn't follow them completely, i changed the location of the stab, the way the stab is built, how much of the fuse was sheeted, etc. I only built one and i lucked out in that it flies great. I didn't have to change any incidences, the elevators are flat with the stab when trimmed for flying.
It looks like you definetly have alot of fuse cross sections drawn, i only had 10 sections and formers to draw.

mulligan

That's good feedback, Terry- thanks. And a very nice project. What software did you use? I couldn't see well enough to tell if longeron locations were on your plans- were they, or did you just place them as you built?

You have a sharp eye to notice all the cross-sections. As I've mentioned in other threads, I am making a scale interior, so the formers are smaller (about .5" radial thickness on a max. 14" diameter) and more numerous (about 40) compared to the norm for models. It's a very tedious process to place the longerons (which are also small and numerous) in the correct locations, especially on a plane with so many compound curves (compound curves = pretty = pain in the ***** to design).

I wish I could get a hold of actual plans, but alas Boeing has not obliged I guess they think they might sell a few more [sm=rolleyes.gif]

canadagoose

My Feedback: (2)

I used MetasequoiaLE for the 3d model because it's free and i can fly the plane on the computer with FMS and sorta see what it might look like flying around. I used TurboCad V7 for drawing the plans, it's a CAD program i got comfortable using really fast. I can't say that for some other CAD programs i've tried like AutoCad R12 for windows and the very first release of ModelCad. I could never get comfortable using and producing much with them. My plane was built on a balsa sheet box crutch that the formers slid onto then quite a few stringers were glued into notches on the formers. The stringer notch locations were drawn on the formers on the plans. Most stringers on the rear half of the fuse are 3/32 x 3/16 sticks, most stringers underneath the sheeting on the front half were 3/16 x 3/16 sticks.
I can see with your plane with all the cross sections and formers and the placing of the stringer notch locations that that's what would account for a huge amount of drawing time at the computer. I know that's what accounted for the majority of time on mine and i didn't have near as many. How will you build the fuse? I take it you will build it on a crutch or jig that is removed afterwards unlike mine where the crutch stays on board?
Good Luck and keep us posted.

ptulmer

My Feedback: (5)

Mulligan,

It appears that your right on track. Lotsa detail. The only way to cut down on the time involved is to use helper software like compufoil.

canadagoose

My Feedback: (2)

Heres a shot of a couple of aftend formers on mine. I see the the plan pic on my project page doesn't really show much.

mulligan

I thought of building in halves (top & bottom), and then joining. That would allow easy building on top of a flat surface but presents a challenge to eliminate/hide the seam on the interior (which I want to be scale). So I'll probably build a (giant) jig and remove it after most of the sheeting and interior is done.

Once I get a little further with the design, I will start a project progress thread somewhere (either in Scale or Scratch forums).

CoosBayLumber

My Feedback: (1)

Well, one thing that has been discussed here before has been actual building. We can easily go ahead and draw up, design up something on a reduced scale basis. However, we are not all two inches tall. Sometimes you can put too many details in such that it cannot be built, except by a watchmaker or one of those fellows who builds ships in a bottle.

There was to be some thought given to actual building, not fidelity to scale. Once the fuselage is joined is there any need to get back inside there again for installation of radio gear, or even acess to the batteries? Do you plan on making the wings a premanent attachment? Oft' times you need to get into the area behind the engine, can it be done?

The crew got in from the back door, is this also going to be your only point of access? I think Chevelle is working out the situation with his own design right now.

Wm.

mulligan

Very good point, Wm. In fact, that's where I think I've spent a lot of head-scrathing time, as someone mentioned before... envisioning a way for access and installation of radio, batteries, retracts, interior components, etc.

My tail servos are located behind a scale hatch, which will be about 4" square, and tail control horns are within a scale tail cone, which is removable. I will do most of the interior work when the plane is partially sheeted; after that, the large cargo doors towards the rear will provide access. The cockpit will be essentially sealed off (although I haven't decided if there's a need for the crew door just in front of the wing LE to be functional. The nose will hinge in scale fashion for access to batteries, switches, and nose weight.

The wings will be three piece: the outer sections will detach in the scale location (just outboard of the engine nacelle) and the center section will be bolted behind scale access hatches. Access to fuel tanks will be through scale fuel tank panels. Most, if not all, wing servos will be mounted behind hidden hatches (something I've come up with that I'll share later... after I prove it works ) My biggest concern is finding engines powerful enough that will fit within a scale cowl (about 8" ). I have a couple of options depending on final weight. Unfortunately, gassers are too big for this- I'm looking at Moki 3.60 (I think I just burned an oz. of fuel typing the name), Laser 300 or 360V, and O.S. Flat Four, but I'll re-evaluate all options once I get close to better knowing the final weight.

I've been a design engineer in real life, and I've been reminded (read yelled at) by guys in the factory many times on manufacturability and maintainability... and I guess I'm a little more cognizant since I'm going to be the one stuck with building the design

All that said, I'm sure there will be aww-sh_ts as I'm building, but hey, it's all fun, right?

William Robison

My Feedback: (3)

George:

Are you planning on the Wright powered version, or the Pratt and Whitney? Visual difference was slightly smaller nacelle diameter with the P&W, but it had a longer cowling to accommodate the two rows of cylinders. And if you use these 7B 41cc engines at 7 1/16" diameter it would be a good fit, good power, and scale appearance.

http://www.technopower.com/1_6_Price...rice_list.html

Marc has a very small shop, and he just about builds to order, so if you order now you might have the engines when you're ready for them. I'm still waiting for him to tell me to send the money for a pair of 7A engines for my current Tigercat project.

Oh, the two power versions. Most civil aircraft had the Wright engines, while the military was partial to the P&W power. While I was a Piedmont ours were mostly Wright, but we had one or two ex-military conversions that were P&W.

Bill.

mulligan

Yes, Bill, I've looked at the Technopowers, but the 1/6 engines don't seem to have enough power... at least the props listed seem too small. For power, I have the 7C (1/5 scale) on my list, but it is 9"- that would be a significant departure from scale... even though it would just look so darn cool. If you can tell me that the 7B can swing a 20x10-ish prop, I would be very interested, but the specified 16x8 seems too small (also, my research thus far suggests 50 - 60cc will be needed). Because of the price of TPs, I'm reluctant to take a chance that they will not have sufficient power. Hmmm... I wonder if Marc would be able to custom build a 14-cylinder engine with two 7As or 7Bs?? [X(] Now THAT would be scale!

Engine nacelle choice goes hand-in-hand with engine choice- I will choose together, although my preference would be for the more shapely P&W nacelle, as it looks better, and as you say the R-1830 was in most of the C-47s. I may also include the rarely used ram filtered dust fillter on top of the cowl (in front of the carb air scoop) if needed to hide a plug.

mulligan

As far as engines go, my original list was:

Zenoah G-62
ZDZ 50NG
3W-50i
O.S. FF320
TechnoPower 7C
Saito FA-325R5D
Saito FA-450R3D
Laser 300V
Laser 360V
BME 50cc
Moki 3.60
DA-50R
FPE 3.2
Fox 4.2

Most of these are not preferable due to size, which is how I pared down the list; I realize I might have to revisit fitting engines within the cowling, but for now I'm aiming high. If anyone has any further suggestions, I'd love to hear them. However, I don't believe a gas engine will work due to power & size requirements.

William Robison

My Feedback: (3)

George:

I can't argue about the power of the TP engines, they are definitely not the strongest engines on the market, but they are the least expensive seven and nine cylinder radials available. And if a radial doesn't have at least seven cylinders it doesn't look "Right." Except for the few planes that were actually built with fives. Three cylinder radials? On one hand's fingers you can count the successful aircraft that were built with threes.

If you will settle for a five, SY in Red China builds bith the ASP and Magnum engines, among others. They make the OS 5R300 with the Magnum label, That one is five 0.60cid cylinders, 3.0 cid total. But the one I'm suggesting here is a larger version, that has five 0.80 cylinders for 4.0 cid total size, 64cc. Their model number FS400AR. It is sold only under the ASP name, as far as I know. And I think you can order direct from SY, as no one in the USA handles this engine. Cost for the pair should be $2500-$2600.

http://www.sanyemodel.com/html/ee.htm

If you have any doubt about SY Machinery, they are the company that makes the RCV engines also.

Bill.

William Robison

My Feedback: (3)

George:

When you go to the SY site click on "Products," then "Four Stroke," and scroll down. Didn't manage to make a link directly to the page showing the radial. And click "Cancel" on the popups asking for a language pack download, the site is in English going in this way.

Bill.