Quantcast

Collaborative Design Challenge – Working Together to Create a Plans-Built Design

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

cheapracer

Well-Known Member
Log Member
Joined
Sep 8, 2013
Messages
6,290
Location
Australian
Exactly. Glasair is a factory producing factory airplanes pretending to be homebuilt. It takes 2 weeks to "build" a Glasair. .
No, it takes 2 weeks to train the owner to be a proficient repairer of at least 51% of the plane's structure in order to be the certified repairman, that's the requirement, nothing to do with homebuilding.

The rule is misunderstood much.
 

TFF

Well-Known Member
Joined
Apr 28, 2010
Messages
14,176
Location
Memphis, TN
Just like in racing, money talks; talent walks. Really just all of human history; not going to change it.
 
S

SvingenB

No, it takes 2 weeks to train the owner to be a proficient repairer of at least 51% of the plane's structure in order to be the certified repairman, that's the requirement, nothing to do with homebuilding.

The rule is misunderstood much.
Do you have a reference for this? this two weeks.
 

cheapracer

Well-Known Member
Log Member
Joined
Sep 8, 2013
Messages
6,290
Location
Australian
Do you have a reference for this? this two weeks.
I'll rephrase it specific to Glasair ...

It takes 2 weeks for Glasair to train the owner of a their new Glasair to be a proficient repairer of at least 51%, i.e. the majority, of the plane's structure in the course of that Glasair's build in order to be the certified repairman of that specific Glasair built. That meets the FAA's requirement, nothing to do with homebuilding.

Other manufacturer's program's to meet the FAA rule may differ, talk to your chosen manufacturer.

The rule is misunderstood much, you do not have to literally build 51% of the plane yourself, the only requirement is for you to have the level of expertise that's covers more than 51% of how your craft is constructed, with evidence of practical construction expertise, in order to gain a repairman's certificate for that plane.

Example; Your plane has 20 similar panels that are riveted on, you only have to prove you are capable of constructing or adding 1 of those panels yourself to demonstrate you are clearly capable of doing all 20, it is not necessary to do 11 yourself. So you get a 100% pass on that paneling.

If the plane has 6000 rivets, you can quite clearly prove you're capable of riveting after 50 rivets, no need to have to do 3001 rivets to prove it. So you get 100% pass on riveting.

Oh, and labour time does not count as part of the 51%, only your abilty.

Rinse and repeat until you are proficient and capable in 51% of the aircraft's construction - get repairman's certificate, get the ladies.
 

Riggerrob

Well-Known Member
Joined
Sep 9, 2014
Messages
1,765
Location
Canada
Several kit plane factories offer "2 weeks to taxi" programs where a buyer uses factory jigs and coaching to assemble the major wing and fuselage components. Back home he completes the engine compartment, instrument panel, paint, upholstery, etc.
Some kits are so complex that they are difficult to build "straight"'without factory jigs.
TWTT is also a quality assurance program for the factory. If they can confirm that all the major structure (e.g. wing spars) are precisely glued or riveted together, they can vastly reduce the risk of in-flight structural failure. A second set of eyeballs is the best inspection tool.
TWTT is a great confidence-builder for a new airplane builder. For example, instead of double-guessing his own workmanship, re-reading the manual 3 times and phoning the factory, he can just ask the experienced factory riveter, who will say "Let's pull all the Clecos and shift everything one hole to the left then it will be straight."
 

Riggerrob

Well-Known Member
Joined
Sep 9, 2014
Messages
1,765
Location
Canada
Less expensive than what?
....................................................................

The latest press release (from the Glasair factory) says that it is easier to build the new Glasair LSA all from composites. Mind you this is in a factory with huge female moods, autoclave, tight quality control, etc.
I assume that the factory is comparing construction costs with the (similar-appearring, 20-year old) Glastar 2-seater. Glastar has sheet-aluminum wings and horizontal tail. The Glastar cockpit is a welded steel tube space frame wrapped in a smooth composite shell.
The new LSA's all composite airframe reduces parts count, tooling costs and employee training costs. For example, if a composite wing worker calls in sick, it is easy to transfer another composite worker from the rudder department.
OTOH Try transferring a Glastar wing riveter to the cockpit welding shop and you will either get a blank stare or horrendous quality!
Hah!
Hah!
 
S

SvingenB

I'll rephrase it specific to Glasair ...

It takes 2 weeks for Glasair to train the owner of a their new Glasair to be a proficient repairer of at least 51%, i.e. the majority, of the plane's structure in the course of that Glasair's build in order to be the certified repairman of that specific Glasair built. That meets the FAA's requirement, nothing to do with homebuilding.

Other manufacturer's program's to meet the FAA rule may differ, talk to your chosen manufacturer.

The rule is misunderstood much, you do not have to literally build 51% of the plane yourself, the only requirement is for you to have the level of expertise that's covers more than 51% of how your craft is constructed, with evidence of practical construction expertise, in order to gain a repairman's certificate for that plane.

Example; Your plane has 20 similar panels that are riveted on, you only have to prove you are capable of constructing or adding 1 of those panels yourself to demonstrate you are clearly capable of doing all 20, it is not necessary to do 11 yourself. So you get a 100% pass on that paneling.

If the plane has 6000 rivets, you can quite clearly prove you're capable of riveting after 50 rivets, no need to have to do 3001 rivets to prove it. So you get 100% pass on riveting.

Oh, and labour time does not count as part of the 51%, only your abilty.

Rinse and repeat until you are proficient and capable in 51% of the aircraft's construction - get repairman's certificate, get the ladies.
OK, but do you have an actual reference to the appropriate regulations?
 

Jay Kempf

Curmudgeon in Training (CIT)
Lifetime Supporter
Joined
Apr 13, 2009
Messages
4,230
Location
Warren, VT USA
....................................................................

The latest press release (from the Glasair factory) says that it is easier to build the new Glasair LSA all from composites. Mind you this is in a factory with huge female moods, autoclave, tight quality control, etc.
Hah!
Wow, those huge female moods normally make most things much more difficult!
 

wsimpso1

Super Moderator
Staff member
Log Member
Joined
Oct 18, 2003
Messages
7,640
Location
Saline Michigan
A couple of comments:

I agree that big plugs and big molds are fragile. A much better scheme than shipping them around is to have each of several builders make a mold for a specific part or parts and then pull parts for all of the participants off of that mold.

I suggest that we build the wing as left and right panels with main spars that overlap and pin to the fuselage with two pins.

Wing shape - Since it is composite, the wing can be almost any shape without making fabrication difficult. I will suggest double tapered (similar to Cessna), with straight to very modest taper for the inner half, and more taper for the outer half. Done properly, it fits close to elliptic shape and efficiency. Fabrication of both tools and parts is easy this way too.

I prefer to follow Harry Riblett's advice on using the same foil from root to tip, same thickness %, and his foils.

My experience is that vacuum bagged wing skins using 22 oz Triax glass for the outside, PVC foam cores, and either of 12, 15, 18 oz Biax glass for the inside works great, is sturdy for subsequent assembly, and light.

If we follow this plan, come up with an estimate of weights and g's, and preferred materials set, I will analyze, iterate, and optimize the wing structure - Skins, spars, ribs.

Will we get on with the design? Before it is done we will need a lot more mission definition, configuration work, and commitment to designing details through an iterative process... Those of you who are not interested in participating, you really do not have to. If anyone else is really interested, let's hear from you.

Billski
 

wsimpso1

Super Moderator
Staff member
Log Member
Joined
Oct 18, 2003
Messages
7,640
Location
Saline Michigan
One more suggestion. Let's get a web site where those of us willing to step up on either design or fabrication can share ideas, get the mission, then design priorities and configuration worked out. After that comes detail design, optimization, tooling etc. We need a place where the folks who are "in" can discuss and collect information.


Billski
 

Riggerrob

Well-Known Member
Joined
Sep 9, 2014
Messages
1,765
Location
Canada
Dear simpso1,

You keener!

Sounds like you are keen on a meeting to freeze mission, configuration, materials and rough-out cabin bulkheads.

When I say "rough out bulkheads", I mean getting the wing and fuselage designers to agree on basic width and height, bolt size and spacing.
They go off to design their individual components and compare notes a month later. A month later, they agree on a couple of compromises and repeat the process.

As for my personal mission and design preferences .... they overlap
between this thread's OP and the VP-22 discussed over on the "21 st century Volksplane" thread. Obviously I want to power it with an Aerovee engine.

I can contribute sewing and drafting skills.

riggerrob
 
Last edited:

Jay Kempf

Curmudgeon in Training (CIT)
Lifetime Supporter
Joined
Apr 13, 2009
Messages
4,230
Location
Warren, VT USA
One more suggestion. Let's get a web site where those of us willing to step up on either design or fabrication can share ideas, get the mission, then design priorities and configuration worked out. After that comes detail design, optimization, tooling etc. We need a place where the folks who are "in" can discuss and collect information.


Billski
Hello Billski and thanks for putting some real thought towards this as a concept. A quick comment on your tooling thoughts. If a skin can be made in a single mold the size of an airplane or wing then smaller skinlets can be made that could be easier to ship. If those parts had joggles on them that say lined up with rib or bulkhead locations then it all would self jig at any location with some plywood templates on a strong back at the final assembly stage at any location. That means any individual tool or shipping box is somewhat minimum. Agreed that members would sign up to making a tool or a family of tools and pulling parts from them. Regional groups could conspire on build nights to share hands and labor. Could work. I am not condoning Bede as a person to follow but he designed a nice laminar wing for the BD-4 that was made of 1' long sections with a rib and skin and a joggle and the flange to bond them onto the spar. Each part was only 5' x 1' x 6" or so. That worked well and was very easy to make the wing around an aluminum extrusion. Not saying design that exact thing but to head in that sort of direction of assembly innovation.
 

Jay Kempf

Curmudgeon in Training (CIT)
Lifetime Supporter
Joined
Apr 13, 2009
Messages
4,230
Location
Warren, VT USA
Warning!!! Long wordy post ahead!


As the title says this thread is an attempt to launch group collaboration on an airplane design of a specific type. Before going into what that specific type is for this particular project, and the details of the project itself, I want to point out that this specific airplane design will likely not be anyone’s “dream plane”. And surely the question will arise, why design this type of airplane – why bother? There are a couple of reasons. First, to establish a process that actual works. For this initial project the emphasis needs to be on it being successful, because if it is not successful then it is a waste of time. But moreover, if it is successful then the process itself could be a model for future collaboration for those that want to see the creation of a design that is perhaps more challenging and rewarding, or of particular interest to them. And to that end I’m choosing an airplane design that is fairly moderate to help make the success of this initial collaboration realistic. Second, in my opinion there are few really good plans options out there that meet the goals of this particular design, actually in my opinion there are none. In fact, unless you have a fat wallet, and a bunch of free time, there are few really good plans available at all.

I am absolutely certain this could be a successful and rewarded project. But to be so, there are several absolutely essential principles that must be strictly adhered to with discipline, moreover group discipline which in my experience is even more difficult to maintain. There are two general areas where these fundamental principles must be adhered to for this to work. The first set of principles are in the collaborative process itself. These are the things that we must always come back to and remember as a group to make the project go forward and be affective and successful. This is the most important part, and absolutely essential for this to work. The second set of principles (if I can call it that) is in the goals of this particular design. Those primary goals will be fee, yet limiting in order to keep the design manageable.

The principles that must be adhered to for the collaboration aspect to work are as follows.

1. Participants must be willing and able to compromise, and thereby go beyond their individual egos for the greater good of the project. This is probably the most significant point. I have been in many group projects and meetings were absolutely nothing gets accomplished because of general disagreement, and incessant bickering, that leads to long wasted time with no results. In my experience this is largely because people come into these groups with strongly held opinions and beliefs, which often come from a limited viewpoint, yet which they equate to be “life wisdom”, and to which they will have absolutely no compromise. It is good and necessary to have opinions and beliefs, and share your real experience. But if you are not coming from an open disposition that allows for the possibility that your way may not be the best or right way, then no forward progress is even possible. You must be open to compromise.

2. Participants must be motivated and committed to this project for one of two reasons. Either they are really interested in this particular airplane design and really want to build and fly one for themselves. Or, they are moved to be a part of this project for the sake of, or in the spirit of, the collaborative process itself. Some may find such a process to be a creative outlet, or simply enjoy sharing their knowledge. Or, as in cultural movements like “Open Source”, they want to contribute their efforts, or ideas, or knowledge, not merely for the sake of the all-mighty dollar, but rather to see it come to life and be disseminated and made freely available to all for the better good of the community. Also, for some who are working in this specific field, they might find this collaboration an outlet to see their work manifest in a built and flown airplane, which they were a part of, and which otherwise may never come to be. Consider that the vast majority of people who think up a design, and even worke on it for years, have never, or will never, actually build that design much less fly it. A collaborate process might be the answer to making ones efforts, if not their personal goals, come to some objective fruition. I am not suggesting that anyone abandon their own project. You can continue your project (or take a break from it) and still participate in the collaboration on the side. And perhaps you just might find renewed inspiration and ideas to help make your design a reality. In any case, the point of this second principle is that if you do not participate with real motivation, and are just hanging out to see what is going on and quick to criticize every step and point out how it won’t work, then this process will not work.

3. There must be an orientation and disposition relative to all design problems as solutions that need to be discovered. In other words, this has to be a process of solving problems, not merely identifying problems (potential or actual) and then meditating on them and elaborating on how they cannot be overcome. There are some “problems” that cannot be overcome, physics cannot be denied. But that does not mean that workarounds and creative solutions cannot be made. Energy should always be directed at solving the problem, not dwelling on it.

4. There must an emphasis and discipline on continuously moving forward, and completing the project in a timely manner.

5. Lastly, I feel there needs to be one to three leaders of the core group. Perhaps one would be the senior engineer, another a experienced composite builder, and the third a project manager, which would assist the engineers with allocated tasks and organizing and managing the project as a whole. Additionally there would be a core group of which these 3 would be a part, with perhaps and additional 2 or up to 8 people who would vote were indecision about how to move forward came up.

For the particulars of this airplane design, there are general design goals, or principle that must be adhered to. Again, these are very general, but as we move forward more details will be established in stages. That way we are sure to not bite off more than we can chew and get bogged down, or overwhelmed, with too many variables.

Also, before getting into the goals, I want to point out that the general characteristics of this design will be similar to a Diamond DA20. Using this plane as a model or guide will keep the design focus narrow enough to make it realistic and perhaps even relatively easily achievable. This is not a project of producing a DA20 replica; I’m using it as a guide for a plane that will have very similar characteristics. Along side the DA20 I want to put up also as general guides two other airplanes that can be viewed as ends of the spectrum. On the left side is the Flight Design CT line of aircraft, and on the right side is the Cirrus SR20/22 line. Both these planes are quite different, I understand, but I feel they are useful as reference points, so to speak, as well as for barrowing ideas and technologies from them. The DA20 fits somewhere in the middle of these two planes, I believe, and is more of a balance, or more moderate, and thus might appeal to a larger group. So, with that the general design goals are as follows.

1. All composite structure – less parasite drag and greater design flexibility.
2. Conventional design 2-place – for reasons already stated. This does not exclude modern innovations or new technology in aspects of the design. For example, winglets might be used as an important modern implementation for efficiency.
3. Low build time – in the range of 1500 hours. I know, not possible right, but it can be. This may be one of the biggest design hurdles but I believe it is also the most important one. Many projects are not started, or abandoned, because they take too much time.
4. Cost under 30K.
5. High efficiency.
6. Comfort.
7. Excellent stability and safety.

Let’s look at some of the details of how the project could work and be managed, and what tools can be used to make it more effective. This forum is a good place to introduce it but to actually get any real work done it would be best to move it to a website created for the project. Anyone can access the website and contribute but only after they have stated they want to contribute and then given a password. Also, the files, like the actual plan, spreadsheets, and 3D models can be uploaded to a repository like Github with access given to all who are participating.

As stated previously there needs to be a core group, or leadership team, however you want to call it, which will act to make final decisions about how the design will evolve. This group should be at least 5 people but maybe up to 11. One person will be the engineering leader and another the project manager to assist him. Odd number because the group will vote were there is disagreement (which there almost always will be), this way we are not endlessly going back and forth arguing over the design options.

To bring does cost and time, not only will the design be a collaboration but the build itself could be a collaboration also. Some of the inefficiency in time and cost could be reduced with a collaborative effort. For example, say you just made a really nice mold for a wing half. You took a detailed 3D file of the part that was provided in the plans, and CNC cut a plug, and from there made a mold out of fiberglass. After you make the part the mold is basically worthless to you, as you won’t likely use it again. This is an inefficiency in time and expense. But if you were collaborating with others, who lived in the same general part of the country let’s say, you could share the mold. Say you have 5 guys that are part of a build group, and each one started at a different point in the plans, one would start making one side of the wing, and another the other side, another the fuse, another the tail, maybe another the cowling. Once each had finished with their piece they would send the mold to another person. That way only one person would have to make one mold.

For the engine and prop of this design, which is the single biggest expense, I was thinking that we could build into the design the allowance for 3 options, the VW Aerovee type at 80hp, the 100hp Rotax, or the Jabiru or rotax 120HP. This is similar to what is offered with the Sonex. If you wanted a cheaper plane with less performance you can use the inexpensive VW, if you wanted better performance you can pay a bit more.

This is getting to be an overlong post, and I’m not sure if there will be any interest at all. So I'll stop here and see if there is any feedback.
Well Nims11,

You have been challenged to put a website up to drive the concept and to allow a place for members to sign up. You game? Wix.com offers such websites for free.
 

wsimpso1

Super Moderator
Staff member
Log Member
Joined
Oct 18, 2003
Messages
7,640
Location
Saline Michigan
Multiple piece wing skins would make for:

Extra weight at every joint - the cloth is automatically doubled at each joint and you always need extra cloth at part edges to help it hold shape at edges and allow assembly without too much distortion;

Extra weight at every joint for adhesive to bond them together - lots of us forget that the glue lines to connect parts weighs substantial amounts, and this will make for a lot more of it.

Extra weight for fairing compound to fill/fair the joints and areas around them as these assemblies will be far wavier than those made with one piece skins;

Extra jig structure and complexity to get all of those skins fairly straight along the length of each wing;

Extra fuss to get the wings to seal if we go wet wing;

Many extra opportunities to build the wings asymmetrically.

Then, do we put the joggle on the outside of the wing? Pretty ugly and draggy OR a huge amount of fairing compound (heavy). Or do we put the joggles on the inside, and accept that the spars will be shallower by twice the depth of the joggles (more weight to get to strength), and requiring more structure (weight) to connect the spars to skins.

Weight is the enemy and this idea starts to add quite a bit. And more pieces is harder to build, and heavier too.

Let's try out an alternative... One partner builds the bottom wing skins, another builds the top wing skins, another builds the main spars, and another builds the wing structure assembly fixtures. Yeah, a few group builds to get the pieces all built. Ship skins and spars to the wing fixture site, and then each partner shows up to assemble their own wing, and then ship a crate with wings home. If a properly protective shipping crate costs substantially more than one-way shipping of it, the crate makes trips between each partner's shop and the wing fixture shop. You could do the fuselage the same way...

Billski
 

Nims11

Well-Known Member
Joined
Nov 8, 2014
Messages
53
Location
ID
I agree that big plugs and big molds are fragile. A much better scheme than shipping them around is to have each of several builders make a mold for a specific part or parts and then pull parts for all of the participants off of that mold.
Very good idea. Plus if you have already pulled one then it would be a bit easier to do 4 more of that same one.

I prefer to follow Harry Riblett's advice on using the same foil from root to tip, same thickness %, and his foils.
I'm wondering if it would be possible in the interest of saving time and cost to use symmetrical airfoils? That way we would only have to make the mold for one half of the wing.
 

mcrae0104

Well-Known Member
HBA Supporter
Log Member
Joined
Oct 27, 2009
Messages
3,647
I'm wondering if it would be possible in the interest of saving time and cost to use symmetrical airfoils? That way we would only have to make the mold for one half of the wing.
Sure, it's possible, but you probably need to educate yourself a little on the performance trade-off. A symmetrical airfoil will have a drag penalty because it will always have to be flying at a higher AoA than a cambered foil. If you don't have a copy, Theory of Wing Sections is indispensable. Barnaby Wainfan's book on selecting airfoils might be a good introduction before tackling TOWS.
 

Nims11

Well-Known Member
Joined
Nov 8, 2014
Messages
53
Location
ID
Not sure what happened to the rest of my post #115 but half of it did not take.

Just when I thought this thread was dead, it came back to life. Thanks Billski for your input.

I'll try to start putting together a website at the end of next week as work is pretty hectic right now.

In the mean time, please keep the good ideas coming. We still need more people involved for this to work.

If you are genuinely interested in participating in this project, please reply stating so.
 

proppastie

Well-Known Member
Log Member
Joined
Feb 19, 2012
Messages
4,881
Location
NJ
There are two very competent (I believe) contributors that have perhaps bought into this idea with concrete offers of expertise. Seems to me those two should get together and design an aircraft even if the camel fails. (horse designed by committee).
 
Last edited:

Jay Kempf

Curmudgeon in Training (CIT)
Lifetime Supporter
Joined
Apr 13, 2009
Messages
4,230
Location
Warren, VT USA
Multiple piece wing skins would make for:

Extra weight at every joint - the cloth is automatically doubled at each joint and you always need extra cloth at part edges to help it hold shape at edges and allow assembly without too much distortion;

Extra weight at every joint for adhesive to bond them together - lots of us forget that the glue lines to connect parts weighs substantial amounts, and this will make for a lot more of it.

Extra weight for fairing compound to fill/fair the joints and areas around them as these assemblies will be far wavier than those made with one piece skins;

Extra jig structure and complexity to get all of those skins fairly straight along the length of each wing;

Extra fuss to get the wings to seal if we go wet wing;

Many extra opportunities to build the wings asymmetrically.

Then, do we put the joggle on the outside of the wing? Pretty ugly and draggy OR a huge amount of fairing compound (heavy). Or do we put the joggles on the inside, and accept that the spars will be shallower by twice the depth of the joggles (more weight to get to strength), and requiring more structure (weight) to connect the spars to skins.

Weight is the enemy and this idea starts to add quite a bit. And more pieces is harder to build, and heavier too.

Let's try out an alternative... One partner builds the bottom wing skins, another builds the top wing skins, another builds the main spars, and another builds the wing structure assembly fixtures. Yeah, a few group builds to get the pieces all built. Ship skins and spars to the wing fixture site, and then each partner shows up to assemble their own wing, and then ship a crate with wings home. If a properly protective shipping crate costs substantially more than one-way shipping of it, the crate makes trips between each partner's shop and the wing fixture shop. You could do the fuselage the same way...

Billski
Hello Billski,

I get all what you say and the comments are based on the general proposal put forth. There is more to elaborate upon this sort of configuration and much to discuss. What I was getting at is that the mold making and skin parts can be modularized in some way to keep the sizes down for shipping and for shop size available. Storing large tools is a ***** and a show stopper for almost anyone. So there are ways to skin the cat.

To make a wing of say 25' span or 12.5' semispan with say 3 ribs you could cut it into three sections and use the joggle to be the part that gets bonded over the area where the rib would be. The joggles could be left out where the skin traverses the spart to eliminate the double triple material problem. The rib cap strip could be the extra strength of the joggle and a flange could be molded into the skin to make the area to bond the rib shear web into. Nuance I know but just an example of how to rearrange the parts to get more functionality out of the same number of layups. That leaves only a small amount of skin that requires some filling and sanding. Same approach could be applied to the fuselage and bulkheads. Use the joggle for the normal flange at a bulkhead. I have scribbled this stuff way too much. I guess being in a production environment for most of my life has me making all kinds of these sorts of compromises that enhance structures that have to be jigged and fabricated.
 

proppastie

Well-Known Member
Log Member
Joined
Feb 19, 2012
Messages
4,881
Location
NJ
Hello Billski,
Storing large tools is a ***** and a show stopper for almost anyone. .
At McDonnell at the transition between CNC machined masters (and molds), The old way was to make contour boards in loft lines department, which were section cuts of the mold line (skin contour). Then string together with internal frame properly alined with holes, pins etc, (devil is in the details here) and have abut 1-2" thick "hydro-cal" (low shrinkage plaster) splined in between the contour boards. Today the contour boards could be 1/8 alum machined on an NC router, there could be foam or plaster in between for your mold..... Just ship the 1/8 boards around, (or make 5 or ten sets).... good luck guys, there are lots of decisions needs to be made.
 
Top