Transferring plans to CAD

looks pretty cool, I think I'll be trying to create some models when the kit arrives- my brother, an aerodynamicist, has volunteered his fluid dynamic skills to help simulate/optimize the cowling shape and venting specific to the model 5 for me. Not sure what kind of effect that will have for another couple of years...regardless... I'll be owing HIM after that lol
 
From what I know the hard part is making the GD&T decisions when things don't exactly line up.. but what you can do with it once you have the models accurate are all great things - fluid dynamics, stress, form/fit planning...
Hopefully lutinplunder will share what his experience has been so far
 
Last edited:
One of the best benefits for me is the ability to create exploded view isometric drawings with all the parts and hardware called out. Serves as a really helpful reference.
 
There is a big difference between creating a cartoon of the bearhawk and a useful model. I am trying for the latter, so far as triumphantduke has stated the hard part is figuring out what to do when things don't line up or given dimensions are off or as I found with the tail when the scale is different between the rudder and the tail fin. I ended up tweaking both until the were close and then adjusting them till the shape was pleasing.
I hope to be able to have all the parts laser/water cut so that there is alot less fiddling with each part and quicker assembly. Alot like how Mike Patey did with Scrappy.
 
Hi - I am planning a plans build bearhawk 5.

I was going to ask exactly those questions re CAD and solidworks for parts.



bear in mind I am total beginner with CAD etc, I have a bachelors in aeronautics and aerodynamics butgraduated in 1999, and my knowledge is a little rusty .I suck at CAD


can anyone answer a few questions for me?

1 - What type of files do I need if I want to cut ribs, skins etc out of sheet aluminium? where I live there is a plasma cutting and water cutting guy
2. Is it possible to use solid works or CAD files to get individual tubes cut, to make a fuselage? or is it something that needs to be done in a jig with a tube cutter / burr ?
 
Be careful who you share your CAD mockups with. Sharing CAD files of Bobs design without his approval may lead to unintended consequences. Contact Bob and telll him what your doing. He may well approve, in the mean time consider keeping your CAD files to yourself. If you have contacted Bob and he approves your effort, get a independent qualified checker to look at your work before sharing.
Gerry
Patrol #30
 
Last edited:
I do agree with you, it is highly unethical to profit from someone else's creative work. IMHO, There is very limited benefit in transferring the prints into CAD. At the end of the day, CAD files do not build or test fly a experimental aircraft for you. lol There is no way to avoid the fact you need a highly qualified builder & pilot to pull off a project of this nature.. ;-0 There is no getting around the truth of the matters at hand. I would not sweat the small stuff GM.
 
I've been a Solidworks user for about 7 years now, and worked as a designer for 3 of those. Your model/assembly looks very impressive. Strong work!
 
I think that the benefit of CAD'ing up the project is likely dependent on the builder's goals, background, and interests. I've found the investment of time in the computer modeling process pretty useful in terms of resolving design and construction questions, but have rationed the time spent in the virtual by restricting screen time to when I need the mental stimulus to get the grey matter TOT into the green (early AM caffeine marination) and when it is late and I'm too fatigued to be safely working in the shop (working tired is working stupid).
 
You can send your tube CAD files to VR3 in Canada and they will send back cut “weldable” tubes. They work in Solidworks. If you send them a full built up model they would prefer that but they will be very particular on how you build your model. Alternatively you can make a flat pattern out of your design and use it to wrap around tubing and do your own notching by hand.
 
Sir Newton hit it on the head....its one thing to draw up your own stuff, it's another thing to give that work (or sell it) to someone else. You get into some wonky legal crap and you are technically stealing from Bob and Mark.

One thing to understand about CAD is "GD&T" reference reference means "geometric dimension and tolerancing"...in shop speak that means how tight of tolerances are you going to run on your parts? What are your edge distance standards for holes in the structure? Where are those standards listed (Bobs drawings or AC43.13 or "asspluck"). Are you considering paint thickness between parts? Are you considering fabric stack-up on the flaps and ailerons.

IMO Bob made his drawings for the general home builder that would put the work in to understanding all the above questions before they started cutting metal. Bend Radius, Edge Distance, Material stack up all go to the tolerances you are building to...get any of them wrong and parts don't fit or will crack/fail over time.

My suggestion is study the drawings and then think about how you will not only build each part but also the complete assembly. Define that process and then look at the tools available to your specific project to get it done. If you live in a area that has a maker space or a CNC shop that you can walk off the street and they will cut your parts...then go build your drawings. If you don't have access to a CNC...think about making your own jigs to build the part. One caution...understand that how you form a part (i.e. water jet, plasma, etc.) can change the properties of the metal and lead to cracking and failure of that part. You're going to spend a lot of time and money to scratch build the wing...it would suck to get it together and realize that you work hardened all the edges of the ribs (HAZ) and they all cracked a year or two into operation.

The greatest value for studying the design is what Spinning Wrench called out...looking at how the bird is bolted together. One off aircraft builds can be built accurately with what Bob calls out in the builder manual. At the end of the day you have to look at time, money and your skills and access to tooling.

Andy
 
I too was once a cad head

but… holding the plans in your hands and sleeping with them under your pillow … you get to thinking

what makes the Bearhawk so special??

you can look at it practically… the merging of 3 building types .. to give you the best of 3 worlds… tube, aluminum and fabric… a nascar rollcage… with the best wing shape made possible with aluminum… covered in the lightest materials

there is the ability to talk and customize your build… being able to talk to Bob on the phone…after only spending a few hundred on plans…(don’t know any other aircraft where this is possible)… correct me if I’m wrong

Bob’s calm manner and generosity surrounds the Bearhawk… you can see it in how we interact on here.. the sharing of ideas … the evolution of the plane

almost everything about the success of the Bearhawk are things that you can’t quantify… the journey...passion for creating something with your hands.. friendship… brotherhood/sisterhood…with those with the same struggle for completion… big or small..

after thinking about such things I turned off the computer and pulled out the pencil and paper .., much like any relationship .., you can’t define it with a formula or data entry

I ask you to turn off the computer … and learn to embrace what makes the Bearhawk special.., and what drew you here in the first place

no amount of silicon chips has been part of the Bearhawks popularity… except for pictures on a website

add your passion to this aircraft..
 
Last edited:
A solid model is not a set of plans; it is a useful adjunct piece of information to aid in understanding the plans, visualize fits, or supporting other analyses/mods/pipe dreams. Yes - I can generate a cutting pattern with a conversion to a sheet metal development or a three-view of a component within Fusion or Solidworks, but ultimately, the model is just another tool. The degree to which it might benefit the builder seems largely dependent on his or her background, training, inclination towards/against squandering electrons, and ultimate goals for the project.

Having one foot in the engineering world and another in craft (working aerospace engineer & custom guitar builder & vintage instrument repairer), I often see discussions on online craft fora that could best be described as 'purity of experience' exercises in craft which are largely absent in engineering. Craft fora typically have channels for those enamored of hand tool-only exercises in historical reenactment, those that choose not to break an edge without a purpose-built fixture, a couple computers, and a bevy of electric motors involved, and just about anything in between. Often, a CAD/CNC/solid modeling channel sits adjacent to and shares members with an 'neanderthal' hand-tool-only channel... with those cross-over members willing to style that tricorn hat on the Neander channel, then slap on the VR goggles for the 'electrons-only' discussions. While those sub-communities may gently chide each other re: their particular obsessions, there is both a modicum of tolerance and a not inconsiderable level of mutual respect accorded between members of those respective groups.

I understand the need to offer the general guidance that solid modeling does not build sport aircraft, but it seems like once that bit of wisdom is imparted, there should be plenty of elbow room available to accommodate those intent on employing the latest tech in their project as well as those that insist on pulling out their Hemmi-made Post Versalog to do basic stuff my phone has done for a decade or two (yes...I am that old, and have the US-made HP calcs and said slide rule to prove it).
 
Last edited:
Last edited:
I used ACAD to draw the parts patterns accurately then we glued the patterns to the metal with 3M 77 Glue. The patterns simplified making all the bits and pieces. The Lee Valley optical center punch spead up setting the punch marks for accurate drilling of the parts. The paper washed off easy with a laquer thinner or with naptha. The sum of the parts will build the Bearhawk and for the rest the Barrows drawings were adequate.I put grids on the paper drawings to get scale and then put the same grid in full size on plywood to make the tail feather jigs. Left & right Horizontal tail were made from the same jig. Combination of old school drafting techniques and technology. Not sure putting the whole airplane in CAD is worthwhile as using the time to make the pieces will get one there quicker. We had one builder visit the shop during our construction who was explaining in lengths the depths he was going to for his construction. We could tell he was lost and mired in the process of the process rather than being efficient, He flamed out shortly after. Best is keeping all the processes simple as possible to get a quality build and keep moving forward. A person only has one life so tackling the project head on and fabricating is daunting a process for a scratch builder. Be careful with the hours spent as hours lost in CAD could have been a lot of parts made with the project advanced further than having hours and days in a virtual creation.
 
yes, I think you are very right (wrt to flame out and 3d not being required/useful)- I'd like to be cautious against efforts that would cause me to flame out. For me personally it is more so if I'm unable to work towards building or find myself with "free" time waiting on something. The main reason to is to practice and develop skills for managing an aircraft throughout its lifecycle within the software I professionally work with. I have a job today, but according to my calculations I need to ensure I keep the job to finish the bearhawk. I'm aware of the shortfalls that can and do occur when a design engineered and produced through drawings is converted to model form. I was curious if any official model progress has occurred, because that saves me time. There's much more than model conversion that I can practice with in the PLM software.

main point, building comes 'first' :) (after house chores, wife, work, kids, etc. etc.)
 
Last edited:
I have managed projects and large maintenance events. It takes serious dedication and there are often days where I would rather have been somewhere else. At work productivity was measured basically as tool time and tool time gets as expensive as one wants. Hundreds of dollars in huge maintenance turn arounds per hour of wrench time. Usually anything over 65% productivity of the tradesman is good. All the hours spent going in tangents that is not producing parts or spent advancing the project physically is diluting the productivity percentage to extend the project timeline. This is not intended to be critical of anyone's initiative but to show the value of concentrated construction time. CAD is an excellent way to make paper patterns of parts so they can be cut out quickly and holes accurately located. Drawing the parts in CAD for patterns can add to efficiency. Our engineering printer was dialed in but they can be printed at home. Put reference marks at 1" spacing and one can adjust the printer scale percent to get accurate patterns at home.
 
I’ve had a lot of success with the tried and true methods of pencil and paper

since we only have a license to build one plane per plans

For the kids reading this… you’ll be much farther along just getting started building with the traditional methods
 
Last edited:
Cool stuff! I like the drawing process - either paper or CAD as think time. Curious to know what you think about this during/after the build.
 
Just another update on my progress. Figuring out the spars/ribs/hinges for the flaps, wing skins and playing around with the idea of solar panels at the tips and the center of the skylight.
 

Attachments

  • photo12644.jpg
    photo12644.jpg
    234.5 KB · Views: 0
  • photo12645.jpg
    photo12645.jpg
    268.6 KB · Views: 0
  • photo12646.jpg
    photo12646.jpg
    313.1 KB · Views: 0
I`ve not read all the posts in here..maybe I missed it...but your flap hinges look like they are beefed up from the originals

never gets old...looking at the Bearhawk design its a great looking plane
 
Last edited:
How much of the solar is Scrapy influenced? :)

I would think the weight in more LiFePO4 battery that charges off the alternator would be a better overall use of weight, unless you have much more solar than that. Unless you see a use case with multiple days in sunlight. Although I like the location choices.
 
You must log in or register to reply here.
Back
Top