# New Ultralight and LSA Trainer design PAIR

## What is your interest/input in such a project?

• ### I think that this is a pipe dream, and you're wasting your time.

• Total voters
25

#### Rienk

##### Well-Known Member
The two dimensional truss (like on the afford-a-plane), filled out w/lightweight formers/fabric seems like a relatively quick and simple way to build a fuselage as well as potentially light.
In reality, that truss is not much (if at all) lighter than a larger truss spread out from the fuselage sides and triangulated. Structurally, the wider you can spread your material, the stronger and stiffer it is going to be. since we are needing a framework for the cloth covering anyway, it might as well be with the aluminum tubing.

I am already looking for options for CNC tube cutting, possibly building our own. I like what Cartesian does Cartesian Tube Profiling â€“ Aircraft Kit Library but we need to be able to do it ourselves. Of course, if we use aluminum, we could always use oversized tube templates and simply use a spindle sander to get the proper profile shapes on both ends. Jig fixtures should be able to take care of everything else.

It's really hard for me to resist my infatuation with composites, and thus introduce design creep... "if only we did a composite tube... what about a composite empennage?... what do you mean it's too heavy?!?"

#### Autodidact

##### Well-Known Member
Oh, oh, I know - PVC pipe :gig:! Seriously though,

Think Geodesic tent. You glue the rod into the thixomolded couplers.
.

This is pretty good, squirt glue into a coupling, assemble quickly, let it dry. The short lengths would take advantage of graflite's strengths.

#### Autodidact

##### Well-Known Member
In reality, that truss is not much (if at all) lighter than a larger truss spread out from the fuselage sides and triangulated
True, but it would be easier and quicker to build.

#### KeithO

##### Well-Known Member
The industrial twin based backyard flyer is $20k Valley Engineering - Back Yard UL-SP The engine package (with prop) is$5k and weighs in at 120lb Valley Engineering - Big Twin

I think an Ultravair 2 cylinder with prop will come in close to that with more power at lower rpm and probably lower weight. But some of the Corvair parts are getting hard to find and will only be more so in the future.

Someone needs to develop a twin cylinder, air cooled, wet sump, direct injected 2 stroke engine. No stink, no premix, better fuel consumption. Just how to pay for the engine development....

I disagree entirely. For many reasons the main reason being cost.

That engine is 2X the retail cost of a 4 cycle industrial engine.

The next reason being market acceptance. I'm sorry but two cycles have long since been relegated to chainsaws and weed eaters in all realms of consumer products. They are currently under attack even in these markets. I like them just fine, but they have operational issues that do not lend them to being ideal for the novice. They are noisy, they stink and they are perceived as dirty. We are going to have to think like product designers, not engineers for this to work. The very first thing that has to be done is make sure that the market will accept your product, then you worry about the engineering.

I think that the two cycle looses on all counts other than wt.

Monty

#### Rienk

##### Well-Known Member
Part of the problem is we have to stop thinking like airplane people. We have this built in bias of how things have to be done. That thinking has got to go. No offense to the aerospace guys, but your training is a liability in this instance. That training is required to build airliners and fighter jets. Aviation is a captive of those industries and the regulatory bodies built around them. We have to get out of that mode.

Forget patents, forget all that crap. Just do it. Disclose everything you do publicly so no clown can try to patent around you. Use the Gnu licensing scheme.

Lets say we take aluminum tube. Then we make some Thixomold split couplers. Then we do something like take a steel compression ring that is swaged over the ends. No welding, no metallurgy issues. No skilled labor required. It's also possible to use carbon pultruded rod which is not so expensive in this manner. Think Geodesic tent. You glue the rod into the thixomolded couplers.

Then instead of fabric, what if we use a heat shrink plastic film over the outside-UV stable of course. Forget all that labor putting on the covering.

Vacuform the doors from PEET or something similar. Paint on the inside. Same for the cowl and any fairings, wing tips etc. CNC bend the tubes and any stiffeners for the doors. In fact you may be able to vacuform wing and other control surface skins. Just build the internal wing structure to take the loads. Instrument panel-vacuform.

Use CNC router to make vacuform tooling. Build your own vacuform machine. This keeps the tooling cost reasonable.

I'm thinking like a plastics, sporting goods, and consumer products guy.

Just throwing some ideas out there.

Trade studies and cost analysis need to be done very carefully. Also environmental degradation, and maintenance criteria.

But, whats tried and true will not get us out of the  pit.

Monty
Good input Monty!

The thixamold concept is already being done with carbon fiber tubing by DragonPlate... this stuff is expensive retail, but it makes interesting trusses. With aluminum, I'm not worried about the labor cost of welding. Offshore or robotic 'should' make it incosequential.
I think there are too many junctions and thus different types of connecters needed to make this cost effective or feasible. From a marketing perspective, I also believe we'd have a huge hurdle overcoming the "erector set" approach. And your design would have to be locked in pretty hard to commit to the tooling.

Still, look at the plastic rib/spar attachments made for the Skylite, called 'Widgets"... Ed Fisher still sells them. i am thinking of injection molded ribs, because they would be fast and cheap - I just don't know what the weight penalty would be (if any).
BTW, the Skylite would be a great UL if it could be manufactured to handle a four-stroke!

The idea of a prefinished surface fabric that can be heat shrunk has lots of appeal - but it would have to be rip-stop material and light. I like what the Skyranger did, but it is not a light enough form of building a UL. Do you have a material in mind? Pray tell.

Our company has vacuum formed fairly large parts in the past (10' x 3' x 2') and know people who do 10' x 20' jacuzzis. We have the stuff to make this work. I really like the material used for Eddyline Kayaks.

We do a fair bit of injection molding, have built many molds here, and are making some large ones in China (for a product used in third world countries). it's not hard to use these tools effectively in a light plane.

We definitely need to take cues from the mass producing manufacturers - especially if they are labor intensive items (the production line of the jacuzzi company looked like a ride at Disneyland, with everthing on a winding track, going from station to station).

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#### Rienk

##### Well-Known Member
The industrial twin based backyard flyer is $20k Valley Engineering - Back Yard UL-SP The engine package (with prop) is$5k and weighs in at 120lb Valley Engineering - Big Twin

I think an Ultravair 2 cylinder with prop will come in close to that with more power at lower rpm and probably lower weight. But some of the Corvair parts are getting hard to find and will only be more so in the future.

Someone needs to develop a twin cylinder, air cooled, wet sump, direct injected 2 stroke engine. No stink, no premix, better fuel consumption. Just how to pay for the engine development....
The Valley Engineering engine is where I learned about the Generac engine. Larry and others have been very helpful; but I think it can be done better.
Porting the intakes, new carb, new exhaust manifold and pefromance muffler will add lots of power. upgrading to race quality valves, pistons, rods, etc can allow even more rpm/power (though I'm not talking about going crazy - reliability is key). Peformance cams and such can make this engine a stellar performer, getting a reliable 50+ hp out of it (maybe even 60 hp with a 1,000 tbo). The beauty is having a pressure oil system,and being able to increase the size of the cooler; plus, it is possible to do a dry sump as well as adding a turbo charger.
FYI the stock carb even has a carb-heat system (though no accelerator pump).

As far as developing a new engine, we've been working on that too. Dave G. and I have been doing a layout, but money is tight and so time available is limited. Beside, it would take some time to come up with the POC, let alone a production version.
The concept is a HO twin, using already mass produced Chevy V8 racing parts (even OTS heads could be used for the POC). However, this would be a liquid cooled engine, so that it can be turbo-ed, and turbo-normalized. According to our initial chicken scratchings, a reliable 80hp should be possible for around 110-120 lbs. Of course, the proof is in the pudding!
We have the contacts for doing the masters, castings, etc. Dave is in the racing industry, so knows enough about power output, thermal dissipation, etc, to be able to do this with a high level chance of success...
But like everything else, it still comes down to money - but with some support from others, we may be willing to pull the trigger on it this year.

Back to reality - the most rugged four-stroke available in the power band needed that I am aware of is the Generac. Very important to me is that we buy NEW engines - not jury rig used blocks (UltraVair). We are intending to manufacture "new" airplanes in a professional manner. We have to stop thinking like garage tinkerers and think like production manufacturers!

If there are other "new" engine options, I'm all ears, but for now, the default seems to be the Generac.

BTW, I have an OEM relationship with a European company that makes a 80hp unit (that is at 1.5 lb/hp (120hp turbocharged version is almost 1lb/hp!), but unfortunately that is just too much weight for a legal 103UL - but is what I recommend for the 2-seat LSA being proposed as part of this design pair.

#### Rienk

##### Well-Known Member
Oh, oh, I know - PVC pipe :gig:! Seriously though, this is pretty good, squirt glue into a coupling, assemble quickly, let it dry. The short lengths would take advantage of graflite's strengths.
Carbon fiber pultrusions are not inexpensive, and I'm skeptical that could afford to tool up for all the required angles, number of joints, etc.
This works well for K-nex toys that are non-structural and are made in the millions, but I'm afraid this is barking up the wrong tree.

I like the concept, so feel free to prove me wrong :emb:

#### Autodidact

##### Well-Known Member
It's not my concept, it's Monty's.:ermm:

#### Rienk

##### Well-Known Member
It's not my concept, it's Monty's.:ermm:
My response was primarily meant for the group.

I have an acquantance in the HSA group that is a huge proponent of geodesic design, but connections are always the achilles heel. i don't have the resources to build dozens of different tools for different connectors, let alone to do all the long term testing to prove their longevity... welding I can handle ara:

Over simplified, geodesic design is just creating effective lattices... spreading loads around a surface - usually to create a large volume or certain shape.
You can continue to miniturize the facets further and further - until, ironically, you end up with the ultimate geodesic lattice - composites! :shock:

I guess another factor that might need to be added to my list is:

"How quickly can we get a product to market." :ban:

(sorry, having fun with the icons)

#### taildragger_sp

##### Member
Airbike and Airbike Tandem.

#### Monty

##### Well-Known Member
Good input Monty!

The thixamold concept is already being done with carbon fiber tubing by DragonPlate... this stuff is expensive retail, but it makes interesting trusses. With aluminum, I'm not worried about the labor cost of welding. Offshore or robotic 'should' make it incosequential.
I think there are too many junctions and thus different types of connecters needed to make this cost effective or feasible. From a marketing perspective, I also believe we'd have a huge hurdle overcoming the "erector set" approach. And your design would have to be locked in pretty hard to commit to the tooling.

Still, look at the plastic rib/spar attachments made for the Skylite, called 'Widgets"... Ed Fisher still sells them. i am thinking of injection molded ribs, because they would be fast and cheap - I just don't know what the weight penalty would be (if any).
BTW, the Skylite would be a great UL if it could be manufactured to handle a four-stroke!

The idea of a prefinished surface fabric that can be heat shrunk has lots of appeal - but it would have to be rip-stop material and light. I like what the Skyranger did, but it is not a light enough form of building a UL. Do you have a material in mind? Pray tell.

Our company has vacuum formed fairly large parts in the past (10' x 3' x 2') and know people who do 10' x 20' jacuzzis. We have the stuff to make this work. I really like the material used for Eddyline Kayaks.

We do a fair bit of injection molding, have built many molds here, and are making some large ones in China (for a product used in third world countries). it's not hard to use these tools effectively in a light plane.

We definitely need to take cues from the mass producing manufacturers - especially if they are labor intensive items (the production line of the jacuzzi company looked like a ride at Disneyland, with everthing on a winding track, going from station to station).
No material in particular, but that thin heat shrink plastic used in the packaging industry is tough as nails and light wt. I'd have to do some research.

I recently did a project using aluminum thixamold connectors and carbon pultruded rod. It was for a consumer product. It's not as expensive as you might think. That is how golf clubs etc are made.

The parts are not that expensive, per part, but that first one off the die is REALLY expensive. Similar to injection molded plastic.
You might even be able to do something with injection molded carbon filled nylon, using long fibers. You could use a mechanically swaged ring over the coupler. You could stick with the aluminum tube if you like.

Trust me, you don't want welded assemblies. Unless it's mild steel trailers, it will be too expensive; a process, and QC nightmare.

I'll think on this for a while. something may occur to me.

Monty

#### Starman

##### Well-Known Member
The trick to using aluminum tubing is to use a smaller number of larger diameter beefy tubes. That way they can handle plenty of bending load and don't all need to be triangulated, plus there are fewer welded joints.

Also the larger thicker tubes make for better welding. Mig welding of aluminum is fast. Mig welding is so fast on aluminum, it's 40 times faster than Tig welding, 30 times faster than stick welding on steel, and 60 times faster than flame welding. I just made those numbers up, not bad huh?

The secret to making welded joints more failsafe in aluminum is to use retainer rings, which is kind of like a fitting, but made from flat plate.

#### Autodidact

##### Well-Known Member
The airplanes I consider to be innovative - planes like the Tipsy Nipper and the Silence Twister - are innovative in a configurational way. At the time they were designed, the construction methods were already well proven. The Windecker Eagle and the Lear Fan are examples of professional engineers getting it wrong with "new" technology. It usually takes some evolution before a new idea is refined to the point that it can be used effectively.

If you can invent a new way to build airplanes and get it to market in a few months (give or take a year or two...), I would be very surprised. You might generate an increment in the move toward a new way to do things, but a step change in the way things are done is highly unusual. There have been such events before though, like Henry Ford's mass production line, or was that, too a refinment of an older idea.....

#### Monty

##### Well-Known Member
The airplanes I consider to be innovative - planes like the Tipsy Nipper and the Silence Twister - are innovative in a configurational way. At the time they were designed, the construction methods were already well proven. The Windecker Eagle and the Lear Fan are examples of professional engineers getting it wrong with "new" technology. It usually takes some evolution before a new idea is refined to the point that it can be used effectively.

If you can invent a new way to build airplanes and get it to market in a few months (give or take a year or two...), I would be very surprised. You might generate an increment in the move toward a new way to do things, but a step change in the way things are done is highly unusual. There have been such events before though, like Henry Ford's mass production line, or was that, too a refinment of an older idea.....
of course you are correct. But the SR71 was built of a new material, they had to invent the manufacturing and everything from scratch....in 2 years. It can be done.

It just depends on how much you want to spend. The key here is to get outside the typical way of thinking, but use a proven technology from another industry. I didn't say it would be a sure thing. Just that we could not keep doing the same things and expect a different outcome. The real problem from my perspective is one of volume. You can get the cost per part down....if the volume is 30K/month.....Aviation is low volume. Tooling to get cost down requires high volume.

We must find processes that yield low volume, low cost....that's tough. CNC, if the programing and design are free.....maybe.

I don't know, just trying to jog people out of their comfort zone.

Monty

#### Rienk

##### Well-Known Member
My brother keeps telling me I should design an ultralight fuselage using this technology. He might be right as it could be highly automated and the parts are light and stiff.

Outdoor Patio Furniture - Wicker Chairs - Wicker Tables - Wicker Plant Stands
That would almost be the ultimate geodesic design!

How is it automated?
It seems that the tooling would be difficult to set up; typically this works best for symmetrical items? How do they 'automate' the chairs and such?
Any idea where to see videos of the process?
Very interesting...

#### Monty

##### Well-Known Member
The trick to using aluminum tubing is to use a smaller number of larger diameter beefy tubes. That way they can handle plenty of bending load and don't all need to be triangulated, plus there are fewer welded joints.

Also the larger thicker tubes make for better welding. Mig welding of aluminum is fast. Mig welding is so fast on aluminum, it's 40 times faster than Tig welding, 30 times faster than stick welding on steel, and 60 times faster than flame welding. I just made those numbers up, not bad huh?

The secret to making welded joints more failsafe in aluminum is to use retainer rings, which is kind of like a fitting, but made from flat plate.

Brazing....below the temp that effects the metallurgy of the tube.

anything but welding....PLEASE I BEG YOU:grin:!!

Monty

P.S....I like welding....but not for production.

#### Rienk

##### Well-Known Member
of course you are correct. But the SR71 was built of a new material, they had to invent the manufacturing and everything from scratch....in 2 years. It can be done.

It just depends on how much you want to spend. The key here is to get outside the typical way of thinking, but use a proven technology from another industry. I didn't say it would be a sure thing. Just that we could not keep doing the same things and expect a different outcome. The real problem from my perspective is one of volume. You can get the cost per part down....if the volume is 30K/month.....Aviation is low volume. Tooling to get cost down requires high volume.

We must find processes that yield low volume, low cost....that's tough. CNC, if the programing and design are free.....maybe.

I don't know, just trying to jog people out of their comfort zone.

Monty
I don't think that all new technology advances need to be developed... I'm not smart enough.
As Monty suggests, we just need to think outside the box some.
Welding aluminum tube is actually "not normal."
Using injection molded parts is outside the norm, but very doable.
What else?

#### Inverted Vantage

##### Formerly Unknown Target
Ok, it's 3 AM here in England so I have yet to actually go through this thread - I'm basically only replying to the first post.
So let's begin - grab a coffee because this is going to be long;

Firstly, while the approach to this problem is interesting, from what I have seen, it is still all being thought out as an engineering question; we need it cheap and "cool looking" - how do we do it? I guarantee you that if you go down that path, you'll end up with something that costs more than you need it to be and it'll only look cool to airplane people who think "looks good" = very efficient and accomplishes it's performance objectives.
I say this because, if you look back on the threads in this forum and history, this has been attempted many, many times, and the approach and result is always the same. Basically: cheap aircraft? simple traditional construction. Advertise to pilots. Sell. Sell tiny volumes because you still can't get it down to less than \$20k and if you DO get it below that, it looks like a flying erector set and maybe 1/3rd of all total pilots will actually get in it, and maybe 1/16th of their wives will actually let them.

So, what do I propose that's different? Firstly, adjust your sights. Shoot for the general populace, NOT pilots. Hell, if I were to be completely honest I would take the risk and focus 95% of my marketing on non pilots, because if you want to get any reasonable sales numbers, THEY'RE the ones you're going to have to go for. Pilots are few in number and dwindling fast, but people who want to fly are plentiful - it's just that it's too expensive, too time consuming, and in the end too boring for many of them to attempt it. (Hell, I LOVE airplanes/flying and I think it's pretty boring boring holes in the sky with a Cessna 150.)

Next up, adjust the way that flight training is handled. I'm glad you mentioned ultralights, because this highly unregulated category is key. See, I believe that training today is too long, too stodgy (more on that in a bit), and too risk-adverse. Let me explain the last statement first, as I can already see some people's fingers chomping at the bit to let loose on their keyboards.
Flying, as it's taught now, is basically only taught in straight lines. Every time you go up, instructors drill into you over and over, "Don't upset the airplane". When you get unusual attitude training, instead of teaching a student how to maybe keep that attitude safely, they are instead only taught to put it back straight and level again - which is fine and very, very safe, but it makes for some very boring flying and some students who are under trained for dangerous situations, or situations where they want to go up and have an exciting time. Before you jump on that, think back to the times when aviation was still really big, when it was an adventure and everyone was amazed at it; do you know one of the main differences between then and now? Obviously the newness, but you know what else? The risk. The excitement of doing things with this vehicle that really showed off the freedom it afforded. So I am not advocating unsafe training by any means, or unsafe practices. I'm advocating training that teaches students how to FLY, not just DRIVE.
As for the stodgy bit - it's related to the part about flight training being too tame. Ever since WWII, the main influence for aviation has been basically the military. Students come in, they are told to do this, this, and this, and then prepare for the test. You will not have any hot dogging, you will follow the VOR to the letter, etc. Ok, yes these are all good talents to have, BUT, it's very intimidating when a new student who just really likes seeing airplanes and wants to learn to fly, comes in and in many instances is basically...how do I say this...shown that he will not have any fun during training? As in, the flying part is fun, but the learning to fly is not. Now I recognize this is per instructor, but it's a general attitude towards newcomers that really has got to go if you want to broaden the appeal.

SO! How do we handle flight training? I'm glad you mentioned ultralights, as that is where I'd like to go. Since it's an unregulated class, you should not just sell this airplane - you should also sell the package training. You can train them on the basics in a two seat LSA aircraft, and then train them on the single seat ultralight in a sim and then finally flying. This gives you complete control over the way they experience flying, and you can tailor it to exactly what you want; something fun, exciting, maybe a bit dangerous but in a good way, with friendly staff and a well managed FBO. The students come in, and you teach them exactly what they need to know to fly ultralights - good handling, basic aerodynamic principles, basic weather avoidance, and then that's it. I also really do mean basic; the stuff in the books where they teach me to recognize 50 different types of clouds and in depth knowledge of compressible flow is quite frankly freaking useless when all I'm going to end up being is a day VFR pilot who only wants to go for joyrides (as an addendum to the previous thing about training; training today focuses too much on long distance flying, when most people never leave a 100 mile radius of their home airport).

Ok, next up, let's see. I want to touch on the look of the aircraft itself; and I will give you these two simple rules: it must look like a real, exciting airplane, and it must look finished. That means no erector sets, no exposed control runs, no fiddly bits hanging out. Also, I second the motion about getting rid of 2 strokes. People don't trust them, hell, I don't trust them - they make the aircraft seem rickety. If you were going to trust your life to a car, would you trust it when the engine cylinders are hanging out the sides or you can see the pull rods that move the wheels? Probably not. So why are airplanes supposed to be different?
Yes, it used to be OK in the classic days, but frankly you have to make the choice; do we want to leave the past as the past and make an airplane that is truly for this new time, or do we want to keep harkening back to appease the old school ways of thinking? Personally I'd prefer the former. It's much, much riskier, but if you do it right, I think in the end the result will be much better.

One last thing that I'd like to look at before I end this post (I have more, don't worry ), is the FBO and why you should have one. It has to look nice, be well kept, and probably have a nice restaurant attached to it. Why do I mention an FBO? Because I'm trying to explain the idea that you should not just sell an aircraft; you sell the whole package. Every thing about this plane should be different, everything about the way it's presented should be different. As much as I hate to say it, you basically have to Apple-ify the experience. How do I mean that? Well, computers (before Apple) were basically sold like airplanes - you buy one that fits your requirements, and you have to be a computer whiz to figure out exactly what that is. The entire experience is annoying because you have to match multiple configurations with different types of software and competing opinions, etc etc etc.
Along comes Apple, where they basically took all the control away from the user and then streamlined it into their own custom made path. This means the user is less free to choose, but when he picks an Apple product, he know that it'll work with all the other Apple products. It also provides a uniform experience for every user that you can make sure is of excellent quality.

Learning to fly is like buying a computer (in the old days). You just want to learn to fly a bit, but you have to go through all this textbook knowledge, compare flight schools, manage your appointments to get down there, make sure you're progressing at a fast enough pace, and of course every flight school and FBO is different.
Sorry if the point got a little lost, but basically; you make the FBO, you dictate how people learn how to fly, you put them in the airplane that you want to teach them to fly (yours, natch), they love to fly in your airplane, you give them rental discounts and memberships, they want to stay with your company, they buy your airplanes later if they want. You build up an entire experience and wrap it around the end user.

That's all for now. Next up is things to actually design the plane for. Before I forget, it's: light aerobatics, easy engine operation, digital integration, and sexy looks.
I'll expand on that later.

#### Rienk

##### Well-Known Member
Brazing....below the temp that effects the metallurgy of the tube.

anything but welding....PLEASE I BEG YOU:grin:!!

Monty

P.S....I like welding....but not for production.
How do you braze aluminum?
I have to admit, we do a lot of welding of steel, but aluminum is not what we know.
Why not welding?

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