# A challenge to you all

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#### Topaz

##### Super Moderator
Staff member
Log Member
...And just to get some clarification, what would be considered a minimalist part 103? After all - some - posters think all part 103 ultralights are minimalist airplanes ;-)
For me, the demarcation occurs when the airplane lacks a defined "cockpit", in terms of "sides", and is primarily wire-braced. Any kind of cockpit sides and actual solid structure for the wings and it's more "airplane" for me than the old "flying lawn chairs". That's simply a demarcation line for me, and I actually like both types. Almost bought a Lazair once, but it was just in too rough of shape. Almost bought a Kolb once, but the seller wouldn't budge on his just-too-high price.

#### Dana

##### Super Moderator
Staff member
...I'm not into PPGs or turboprop flight-level cruisers, but I'd never tell anyone that those types of aircraft are a waste of time. They're a ton of fun and use for the people who enjoy them.
Right. I like my PPG, but it's really a completely different thing from flying any other kind of aircraft... more of an aerial dirt bike, and the PPG "scene" is closer to the skydiving scene than to any other kind of airplane... and a large part of the fun is in flying with friends. Solitary PPGers tend to lose interest.

I'm not really a fan of ultralights, especially for training so I've been staying clear with my "negative ways" (said with a smile) but one plane that is often missed that I really liked years ago (and that was relatively cheap to build) was the old PDQ-2. I don't have pictures but a brief search might reveal some.
I too was fascinated with that one way back when, and doodled numerous designs based on it when I was in college. I wanted to design a plane much like it as my senior design project but my professor wouldn't accept it; I guess he didn't think it was serious enough. But that engine location on the pilot right behind the pilot's head looks particularly bad from a crash survivability standpoint...

For me, the demarcation occurs when the airplane lacks a defined "cockpit", in terms of "sides", and is primarily wire-braced. Any kind of cockpit sides and actual solid structure for the wings and it's more "airplane" for me than the old "flying lawn chairs". That's simply a demarcation line for me, and I actually like both types. Almost bought a Lazair once, but it was just in too rough of shape. Almost bought a Kolb once, but the seller wouldn't budge on his just-too-high price.
So where does my Kolb fit in? No cockpit sides, but it's not wire braced. Though the Kolb structure is more "aircraft like", unlike the hang glider derived planes like the Quicksilver series.

There are really several broad categories of ultralight airplanes (not including the other forms like PPG, PPC, and weightshift). There's the classic "flying lawn chair" like the Quicksilvers, bolted aluminum tube and sailcloth, open and wire braced (though they do have a strut braced model). There are enclosed planes with the same construction (Challenger, CGS Hawk, Flightstar), open or closed designs with more conventional aircraft construction and doped fabric instead of sailcloth (Kolb), and newer plastic designs (ZJ Viera, a beautiful design except for the frightfully ugly engine mount). And of course the categories overlap.

Note that the strut braced Quicksilver is actually heavier and less rigid than the wire braced ones, the only advantage is that it can clear a lower hangar door than the wire braced versions with a kingpost. Quicksilver also sells a fully certificated (Primary category) 2 seater, their GT500-- fully enclosed (zippered fabric doors), bolted tube and sailcloth. Why they haven't gone for SLSA certification on their other models is beyond me.

-Dana

If the aliens landed and asked if we had space travel - we would, of course, say yes. And if they asked how we do it, we would have to answer:
We assemble the largest collection of liquid hydrogen, oxygen, and high explosive we can find... and then we put a man on top and TORCH the son of a *****!
And you know, they might really be impressed!

#### Topaz

##### Super Moderator
Staff member
Log Member
...So where does my Kolb fit in? No cockpit sides, but it's not wire braced. Though the Kolb structure is more "aircraft like", unlike the hang glider derived planes like the Quicksilver series....
Squarely in the grey zone. There has to be a grey zone. :gig:

#### BBerson

##### Light Plane Philosopher
HBA Supporter
Alan's (Head in the clouds) Macro is indeed neat looking and is the type of aircraft where my interest has been since the 80's.But with 6.5 lbs. wing loading it does not qualify as a U.S. ultralight unfortunately. The Macro is a "light plane" or some other term (wish I new the correct word).Much of the conversion of small four stroke industrial engines is here:Small4-strokeEngines : Flying with Small 4-stroke EnginesDifficult to use these engines for a legal ultralight with the required large wing span to get 3.9 lbs/sq.ft. needed.But should work for a "light plane" with much smaller wing and somewhat higher landing speed.BB

#### George Sychrovsky

##### Banned
The PDQ is bad configuration deadly by the design. Years back another company came up with what some called PDQ copy which it really wasn’t but very similar called Warp 1. They took it to Sun n Fun where on the first flight it wasn’t climbing and stalled at the end of the runway killing the pilot, the engine came down on the pilot and crushed him.
To make the story even more interesting few years after someone picked up the design again sold like 40 of them
(real cheap) then disappeared with all the money delivering nothing.

#### deskpilot

##### Well-Known Member
FWIW. Like many, I'm penniless with a passion for flying. You've seen my 'dreams' on this site and all have come to nought due to over complication or turning out to be way too expensive in one way or another. Most of my designs have been aimed at 'going somewhere' which means a cruise speed of something in excess of 80 knots (92.2mph). Recently I've changed my direction to that of just flying locally as it's better than not flying at all, and have thus started on a 95-10 category (103 equivalent) design. Here's a couple of early 'concept' images.

Based on Andre Stark's AS-37 it now has the forward pedals, panel and some tip over protection added and the wings have been fully cantilevered. A central 60hp engine will power the 2 contra-rotating props.

Not wishing to take over this thread, but all comments welcome. I guess that even includes negative ones from G.S.

##### Well-Known Member
How refreshing to wake up to a thread that's vibrant and oozing enthusiasm!

It's clear that there is an interest in Pt103 types after all, and that if something can be done about designing a low cost plane with really good looks and handling to fit within the category then there could be a resurrection of cheap fun flying. Thanks to one and all contributors for their excellent suggestions so far and examples of what people might be looking for.

Having defined starting points (the engine suggestion) and specific goals, (the look, pilot protection etc) then half the battle is won. I think if we start with a general concept and allow suggestions and contributors' sketches to morph the initial shape, we should be able to quickly define a shape which the majority will find appealing, then if we can put up structural and materials suggestions we might be able to prevail upon the engineers and aerodynamicists among us to contribute their time to refine it and get the weight as low, and the handling as benign, as possible.

I’m a 3D draftsman and will be pleased to offer my time, as work pressure allows, getting the modelling underway, although I know we also have some 3D CAD modellers that do a better job with CATIA and the like, than I do with AutoCAD.

As I mentioned earlier, I have kept a sketch made by a friend over 20 yrs ago that has intrigued me by its simplicity, attractiveness, inherent strength, pilot protection and potential for very light weight and reasonable performance from low (cheap) horsepower.

This plane was conceived during the ‘attention to detail’ ultralight design era, when we had abandoned the ‘back of a cigarette packet’ design process and recognised that if you wanted to draw something truly worthwhile you had to use a whole sheet of paper. Funnily enough many of the 1980s ultralights had no further design detail actually drawn than a three-view sketch, the rest was in the would-be builder’s head, and it was usually flying within three months from the sketch being committed to paper.

Barry Hughes, toolmaker extraordinaire, is responsible for this little masterpiece. Baz was the first ultralight CFI in my home state of Queensland which is a vast area approximately 2000Nm north to south and 1500Nm west to east. Baz was appointed u/l CFI when we were just starting to push the DoA into accepting that we needed some form of basic ab-initio training to cut the crash rate which was accelerating as ultralights became more popular. Nonetheless DoA would not initially approve any form of two seat training aircraft so Baz successfully taught dozens of early u/l fliers in their own single seat aircraft. He got them to run up and down the strip learning rudder with a throttle that was limited in its travel. Once they could keep straight he would use a motorbike to run along next to them as they progressed to strip hops and eventually to solo circuits. As far as we know none of his trainees ever came to grief and all were encouraged to go to a gliding centre for spin training. Baz also taught his own son to fly that way.

To avoid this becoming too long I’ll post the sketch now and go on to describing the features that I like about the design in the next post. Not all is obvious from the sketch, so please be kind to it until you have the rest of the details…

##### Well-Known Member
FWIW. Like many, I'm penniless with a passion for flying. You've seen my 'dreams' on this site and all have come to nought due to over complication or turning out to be way too expensive in one way or another. Most of my designs have been aimed at 'going somewhere' which means a cruise speed of something in excess of 80 knots (92.2mph). Recently I've changed my direction to that of just flying locally as it's better than not flying at all, and have thus started on a 95-10 category (103 equivalent) design. Here's a couple of early 'concept' images.

View attachment 17600View attachment 17601 Based on Andre Stark's AS-37 it now has the forward pedals, panel and some tip over protection added and the wings have been fully cantilevered. A central 60hp engine will power the 2 contra-rotating props.

Not wishing to take over this thread, but all comments welcome. I guess that even includes negative ones from G.S.
Hi Deskpilot, glad you've joined us. Umm...don't know how to say this, I like your design but under ANOs 95-10 and 101 I'm pretty certain we're not allowed more than one engine and one airscrew...

#### Hot Wings

##### Grumpy Cynic
HBA Supporter
Log Member
but under ANOs 95-10 and 101 I'm pretty certain we're not allowed more than one engine and one airscrew...

Did a quick search. Didn't find these regulations. Can you point me to where I might view them? Would like to see how my part 103 might need to be changed to meet your version of an ultralight.

##### Well-Known Member
The SKY-RAY design features -

Wire braced without needing a kingpost, and without taking the wires to the axles so you can still have large suspension travel.

The need for good separation between the top and bottom wire connection points encourages a reasonably deep fuselage which suits the 'expanding size of the population' and means we will have 'man-sized' aircraft.

Wire bracing provides for two support points along the spars (rather than one if it had struts) for much stiffer/lighter structure.

Pilot is seated on the CG so no need to ballast for differing pilot weights.

Pilot protection is good. It is not an 'arrival machine' where the pilot is the first thing to arrive at the destination (particularly if it is a crash site...) and that is good for all and particularly the less experienced flyers.

Excellent rollover protection.

Design is well suited to pop rivetted industrial grade square tube (radiused corner) and gusset construction for the fuselage and tubular front/rear spar wing with tubular rivetted built-up ribs. Internal compression struts and internal wire drag/anti-drag bracing. Stits/polyester sewn bag covering, heat shrunk with dope etc...

Could be tailwheel or nosewheel by reversing the wishbone of the maingear (side for side swap), yes the wheels are shown too far forward in the sketch of course.

No need for a lower cowling, run the centre and lower longerons all the way forward to the spinner and truss them all together to form an engine bed. Add 'power bulges' each side if it's an inline twin 2 stroke, one side shrouds the carbys and the other side covers the exhaust bend, put the muffler under the engine to fully conceal the ugly thing...

One person rigging, carry-on-your-back/drag the wing up to the side of the fuse, leave wingtip on ground, connect spars and flying wires, prop-up the wingtip, connect the landing wires with an overcentre snap toggle which tensions them, apply safety pin, connect controls, done.

Simple design to incorporate aerodynamic balance on all control surfaces, made from bent tubing. Convenient place to install minimum weight mass balancers.

Using tapered control surfaces is a neat way to provide attractive shape to a rectangular wing.

No wing root fairing is needed and the 'cut-away' in the inboard flap area provides easy access for ingress/egress via the rear spar.

Open or closed cockpit simply by adding a wrapover from windshield to turtledeck, wrapper can be carried in fuselage baggage area behind pilot.

Large control surfaces for good low speed handling and controllability in turbulence/crosswinds etc

Go for it HBAers, tear it apart, improve it, discard it, hate it, love it - it's just a conversation starter if you like

##### Well-Known Member
but under ANOs 95-10 and 101 I'm pretty certain we're not allowed more than one engine and one airscrew...

Did a quick search. Didn't find these regulations. Can you point me to where I might view them? Would like to see how my part 103 might need to be changed to meet your version of an ultralight.
My apologies. I'm amazed, it looks like 95:10 has changed and I didn't notice it. 95:55 (for two seaters) still has that restriction. Here's a link, you can also find the 95:55 on the CASA site - Civil Aviation Order 95.10 - Privately built single place ultralight aeroplanes - Exemption from compliance with certain provisions of the Civil Aviation Regulations 1988 (12/12/2004)

#### Hot Wings

##### Grumpy Cynic
HBA Supporter
Log Member
I'm amazed, it looks like 95:10 has changed and I didn't notice it

I hate it when that happens to me. So, it looks like anything that we can dream up here in the US that meets our regulations would fall under your version of an ultralight as long as the wing loading is under 30/M? It also appears that kits are acceptable but not finished aircraft.

#### StarJar

##### Well-Known Member
Looks simple and fun. I especialy like the idea of the 'engine bed'. Maybe throw an extra member behind the engine, to satisfy our new awareness of crash safety.

I also like the landing gear. With three tubes on each side (Cub style/tripod), the whole landing gear can probably weigh less than 4 lbs. (not counting axle and wheel). I was investigating gas springs to use as one of such legs, and it seems like they could work. They weigh about 2 lbs. each.

Flying wires seem great for the speed range. Light, cheap, and of course strong.

I still want to see the Robin's wing, and how he made that long wing so light, (and the whole airplane for that matter). A shorter version (wing) could be equally revolutionary, with less exotic materials than his long wing. Untill then I like flying wires, for the reasons I stated.

Interesting design.

##### Well-Known Member
I'm amazed, it looks like 95:10 has changed and I didn't notice it

I hate it when that happens to me. So, it looks like anything that we can dream up here in the US that meets our regulations would fall under your version of an ultralight as long as the wing loading is under 30/M? It also appears that kits are acceptable but not finished aircraft.
Yes, that all sounds right by my interpretation, and definitely not completed aircraft. Also check the 95:55 category because it has a much greater weight limit (600kg MTOW) and 2 seats etc, but definitely only one engine/one airscrew. For much more detail about our regs/ops have a look at the very informative RA-Aus site, note that the first link will take you to the new (under construction) site, the old site (see link on home page of new site) has loads more information - Recreational Aviation Australia

Here's the old site link - Recreational Aviation Australia Incorporated web service

##### Well-Known Member
Looks simple and fun. I especialy like the idea of the 'engine bed'. Maybe throw an extra member behind the engine, to satisfy our new awareness of crash safety.

I also like the landing gear. With three tubes on each side (Cub style/tripod), the whole landing gear can probably weigh less than 4 lbs. (not counting axle and wheel). I was investigating gas springs to use as one of such legs, and it seems like they could work. They weigh about 2 lbs. each.

Flying wires seem great for the speed range. Light, cheap, and of course strong.

I still want to see the Robin's wing, and how he made that long wing so light, (and the whole airplane for that matter). A shorter version (wing) could be equally revolutionary, with less exotic materials than his long wing. Untill then I like flying wires, for the reasons I stated.

Interesting design.
Yes, that Robin certainly has heaps going for it, I've been off in such a different direction for so long I hadn't heard about that project at all. Really glad Topaz mentioned it here.

And Baz's Sky-Ray undercarriage does have a lot going for it, with a long monoshock or gas spring as you suggested you could set up the geometry for a very long travel using that external compression idea, rather than the tension bungee setup as used on the Cub. And that means it could be soft suspension to give excellent rough field capability as well as shock absorption if you want to thump it down for a really short field landing, Storch fashion... If it's not going to be a speed record holder it might as well have good STOL capabilities, and bush tires for off-roading, smaller tires and wheel pants for the city-slicker.

One of Baz's friends has a really simple tailwheel setup with long travel suspension, all of it is mounted to the base of the rudder spar so no chains, cables, steering springs etc. My first thought was not having enough steering angle but he just gave the pedals longer travel and the rudder more angular deflection than usual. Also he made the rudder spar the main structural element and supported the fin off it, instead of the other way around. A good bit of lateral thinking since he already needed a strong rudder spar to carry the tailwheel loads. I'll see if I can get a photo of it sometime, it's another very cheap and light concept worth having in the toolbox of this enterprise.

About throwing that extra member behind the engine - did you have anyone in particular in mind? :gig:

#### StarJar

##### Well-Known Member
And Baz's Sky-Ray undercarriage does have a lot going for it, with a long monoshock or gas spring as you suggested you could set up the geometry for a very long travel using that external compression idea, rather than the tension bungee setup as used on the Cub. And that means it could be soft suspension to give excellent rough field capability as well as shock absorption if you want to thump it down for a really short field landing, Storch fashion...
This is definately true, especially if you get shocks such as 'Fox Floaters'. These are also light, and you can get any length of travel. They are about $200 each and$39 each for the more bouncy 'gas springs'. This is technology, that probably would have been used on Cubs, if it was around then. So why not break the mold, and do what makes sense?

Following a similar philosophy, regarding wood, is Spruce really the 'holy grail' it's made out to be? (We're really pushing the limits on this thread.) I have this feeling that back in the mysterious days of aviation, they did a study, and Spruce, being found to be the most ideal for aircraft, cast a mysterious shadow of suspicion on other woods.

What I'm getting at is that most Pine species, have almost the same strength- to-weight ratio as Spruce; they're a little weaker, but by the same token a little lighter. (I'm talking about 5% weaker (per area) and about 5% lighter) But cost wise, jeees, if you go to a lumber supply that caters to cabinet makers, you can usually get, or order, long, clear vertical grain pine planks, that are suitable for aircraft structure; and you are going to save a bundle of money.

I'll admit that I'm not an expert on this, so if someone wants to correct me, please do.

Roger Mann, of Ragwing Aviation, used to send out an FAA wood grading specification sheet with each of his plans, so you could select aircraft quality peices of wood from your local lumber venders. I think the sheet delt with Douglas Fir, but to me Pine makes a lot of sense on an ultralight, because you will use a slightly larger peice (circumference) and improve you're buckling strength and gluing area as well.

But if someone knows more about this, I think it would be ideal information for these smaller lighter airplanes (and wallets).

One of Baz's friends has a really simple tailwheel setup with long travel suspension, all of it is mounted to the base of the rudder spar so no chains, cables, steering springs etc. My first thought was not having enough steering angle but he just gave the pedals longer travel and the rudder more angular deflection than usual.
Cool.

Control wise, whichever had the most authority, tail wheel or rudder, in any given situation, would be the one controlling the airplane, so that should work fine, I would think. Simpler and cleaner.

About throwing that extra member behind the engine - did you have anyone in particular in mind?
Oohh yes I did. (I'm shaking, like I did one time at church.)

#### BBerson

##### Light Plane Philosopher
HBA Supporter
The Sky-Ray looks very light. But why use thin wing tips? For an ultralight (or any airplane) the tips needs some thickness, sometimes more than the root in percent chord, to avoid tip stall and give more lift in general, I think.
BB

#### Topaz

##### Super Moderator
Staff member
Log Member
With regard to wood selection and spruce, the topic has been covered extensively here in the forums (seems to be an almost annual discussion), and a search should turn up that material.

##### Well-Known Member
The Sky-Ray looks very light. But why use thin wing tips? For an ultralight (or any airplane) the tips needs some thickness, sometimes more than the root in percent chord, to avoid tip stall and give more lift in general, I think.
BB
Good point BB. I think it's like that in the sketch just as a bit of artist's licence because it looks better that way. In fact when we were building wings that way they were the same thickness (if the wing was constant chord (hershey bar?) all the way to the last rib and then a simple wingtip was formed by having a tube curved around from the l/e spar to the rear spar and the covering sewn in a similar shape. That avoided having moulded tips and also took the load of the shrunk fabric off the tip rib.

Later a bloke did make the tips much larger, his idea was that having to have 100 sq ft of wing area was a real drag (literally) so he bent the intention of the rules a bit by having the area but the outboard 5ft or so of each wing was almost flat. It was a good deal faster in cruise but predictably it had horrible tip stall tendencies. We didn't know much about aerodynamics then. Wish we'd had an HBA back then to scoop up all the valuable stuff that smart folks so willingly impart to those of us less versed in the specifics.

While we're on the subject, any comments on wingtips everyone? We're trying to keep the whole thing simple and quick to build, and can avoid having wing root fairings with this configuration and likely cruise speed. So should we avoid molded tips as well and use a tip as described above, but very short of course?

And does anyone want to post a sketch of any other configurations we should consider?