A challenge to you all

Discussion in 'The light stuff area' started by stan40353, Sep 11, 2011.

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1. Jun 27, 2012

stan40353

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nice video. thanks!

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2. Jun 28, 2012

Topaz

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Exactly.

Gentlemen, you've now wasted pages arguing about one particular wing structural concept that none of you except gordonaut seem to want to use, endlessly debating every fine point of semantics on the subject of "buckling", all so someone can say, "I'm right and you are wrong."

The original intent of this thread was to work towards some group design of an ultralight aircraft. The last few pages have been anything but that topic. How is this argument moving your project forward? This is precisely why I suggested the group needed a strong leader or (small) group of leaders. To say that this project has become rudderless is a gross understatement.

I agree wholeheartedly with Stan. Let's get this thread moving forward productively.

Last edited: Jun 28, 2012
3. Jun 28, 2012

Hot Wings

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How about off on a slight tangent?

Here is what I've been thinking about after reading this and the Affordability of Aircraft thread. Since it's pretty obvious that the affordability of aircraft debate seems to revolve around a set of circular problems, (which came first the chicken/lots of pilots or the egg/cheap aircraft) someone somewhere needs to just jump in on faith and do something to change this pattern. Rather than build a classic part 103 ultralight how about doing one that fills the same niche as the old SG-38 primary glider, but with a small electric sustainer, that meets part 103 specifications?

Such an aircraft would have to be easy and predictable to fly, rugged and easily repairable, trailer-able and store-able in a single stall garage, cheap to build from easily obtainable materials, and have built in occupant protection to make injury during training flights improbable. Is there anyone else out there that would be willing to put up around $3k to build such a plane and then volunteer some time to give a few free lessons to interested persons? I'm seriously considering this, even if I have to do it solo. It wouldn't be a practical ultralight, but it would be cheap and maybe even a bit of fun. stan40353 and Topaz like this. 4. Jun 28, 2012 Head in the clouds Head in the clouds Well-Known Member Joined: Mar 11, 2012 Messages: 1,983 Likes Received: 890 Location: Gold Coast, East Coast of Australia (...) removed by moderator, reply to deleted post. HITC then addresses Gordonauts 2nd proposed concept: I quite like your truss spar but I can't allow myself to not point out a couple of minor things which I would do differently. There are small sections of the spar, the part that each rib occupies, which have bending moments since the truss is not fully resolved, and that is not structurally ideal, requiring the truss chords (spar caps) to be larger than they really need to be. Also that structure would be quite fiddly to assemble since you have to be rivetting while the ribs are in place. I could imagine the ribs getting some damage while rivetting. If you made the ribs in two pieces instead of one you could make and assemble a fully resolved spar, probably using a sheet web and then glue the ribs in place afterwards, the sheeting would hold them just as securely as locating them between the caps, and you can still rivet or bond the skins to the caps to prevent wrinkling, which won't happen anyway of course since we now have a much stiffer wing than the previous version. Otherwise it's quite a good way to go. I'm under pressure at work just now but I have a different proposal which I will CAD model as soon as I have time and which uses tubular front and rear spars, fabric covered, quite similar to the belite method. As part of the exercise I will be calculating the weight of all components of the wing. If you wanted to do the same with your concept I think it would be useful to be able to compare the weights of each. Last edited by a moderator: Jun 28, 2012 5. Jun 28, 2012 litespeed litespeed Well-Known Member Joined: May 21, 2008 Messages: 1,493 Likes Received: 296 Location: Sydney Hey guys, Gordon, I did quickly comment on your second design- I found it much improved and more inherently stable. I did not go further but think it needs a few simple refinements. Clouds, Be good to see your design idea- the belite seems fairly succesful, a cheap homemade version has a lot of potential. They have used a carbon set of spars so that adds bucks but I am sure a suitable alloy version could be made. Note they do a all carbon version as well, bit lighter and quite a bit more money. They also do a carbon upgrade for the elevator- more bucks. Fuselage wise they also have options to suit your wallet- or how much they can extract from it. You can have a all steel- CroMoly, partial steel (Cockpit), with alloy rear frame or a All alloy frame with the cockpit in welded alloy 2"x2" tube and the rest riveted alloy. Add in the huge options list/ways to get your money, and a lot of scope for a cheap homebuilt exists. One thing I do really like is the instruments they make- cheap and very,very light. A whole panel of 8 is less than 2lbs. And sub$1000 set up is easy.

Lots can be learnt from this manufacturer.

As a final comment..........

The products of this forum is safe aviation in home built aircraft, knowledge and a brother/sisterhood of fellow wingnuts.

In this aviation game, there is no winning a argument, just living the experience and surviving to fly again another day.

I am taking my own advice and chilling out, having a beer and a quiet smoke. It is good to reflect, rather than jumping to type.
:grin:
Phil

6. Jun 28, 2012

gordonaut

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Last edited: Sep 25, 2012
7. Jun 28, 2012

litespeed

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Gordon,

I do not see a picture?

Bit hard to visualise without.

Sometimes the site is hard to post images, that and I have a microcrap laptop.

8. Jun 28, 2012

litespeed

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Gordon,

About the Belite, I find the figure of 500hrs to scratch build the wing and cover it- a far stretch.

The wing for each side is two off the shelf carbon spars and a series of alloy or carbon ribs (5?) and simple false ribs. It has some internal bracing which is simple tube and bolt, at the root is has a wooden ply rib. It is covered in lightweight cloth. The wing is assembled with a 3M epoxy glue.

It is actually a fast build wing design as far as wings go. I would be able to make all the ribs and false ribs in a 2 days from alloy and ply.

The wing spar is bought and a flat table made and you assemble and add reinforcments a day each wing.

The cover and paint 2 days.

Yes a few machine bits are involved for the flaperon but that can be made from plate alloy or farmed out.

double the times above or even triple them and the hours are not huge.

Thats not much time, i doubt more than 150hrs from scratch, for a slow builder.

For a kit set , I would think a set of covered wings could be built by two friends and covered in a weekend.

Whilst these are just estimates and depend on builder skill and tools available, it is a very efficient time wise build for a cloth wing.

For those of us blessed with reasonable rules and can be heavy, it is easy to add extra ribs and rods to get greater strength.

Just my two beers worth

Phil

Last edited: Jun 28, 2012
9. Jun 28, 2012

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Moderator note. I have removed posts and parts of other posts. Keep the discussion on-topic, non-argumentative and without flaming or personal attacks/characterizations. If you can't, your posts will be removed and this time without the courtesy of leaving the on-topic parts here.

If you can't post in a constructive, respectful and non-argumentative way, then don't reply.

10. Jun 28, 2012

Autodidact

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OT {on tangent :0)}, I think that the Skypup could be converted to a primary glider very easily - just raise the wing a little, move the pilot forwards a bit, and use the strong nose structure to attach an engineered, streamlined crush-zone nose made from layers of foam. Use a HANS device so that a kid (or anyone else) could dive straight into the ground from 20 feet without a neck injury. And you could spend some enjoyable days bungie launching people of all ages to get the feel of actual flight - just need a big field...

OT (on topic), I think that the built up spar from extruded angle would be much stronger than it would need to be. For this ultralight, short span biplane, a simpler spar, C-section bent up from sheet, would be plenty strong enough, and bonded or otherwise attached to the skin, the skin would then form part of the cap. Rib blanks could be bonded to the spars (front and back) and after bonding the whole spar/rib blank assembly could be hot wired to the airfoil shape (have to use the right foam); anyway, just a thought...

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11. Jun 28, 2012

litespeed

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Of course there are many versions of a two spar cloth wing, some are sexier/sportier than others.

For me a Fokker DVIII replica would be perfect. Another quickish to build all alloy beasty designed as a WW1 fighter.

I have visions of my fighter scanning the horizon, machine guns ready...............

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12. Jun 28, 2012

Detego

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13. Jun 28, 2012

Autodidact

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Nice drawing !

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14. Jun 29, 2012

litespeed

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Must agree that is a nice looking glider.

Got a powered version, maybe even electric?

Much sexier than a skypup. Could be tweaked with curves with little extra effort for those inclined to build deluxe.

Nice

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15. Jun 29, 2012

Detego

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Here's the simple side-view in dxf format.

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16. Jun 29, 2012

topspeed100

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I like the drawing..is the foil from an unlimited racer ?

17. Jun 29, 2012

Detego

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The airfoil shown on the Glider (LX4-215_xMod) is one I created in 1978 to replace the RAF48 on my KR.

For an Unlimited Racer you'd want something like my LX6-155A (attached).

For the glider, I was also looking at using the RXM5-217 and reducing the wing chord to 44"/1118mm (attached).

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• LX6-155A_48.dxf
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18. Jun 30, 2012

PorcoRosso

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After being directed to this post, I seem to go along with the same idea of having an efficient, affordable Ultralight that works with Part 103. Though I cannot build or fly myself at the current moment, I do have concept designs that if willed to, can throw out here and there. Many of them are Altered design ideas sprung up from Mike Sandlin's "Basic Ultralight Glider", and after seeing a few videos of the GOAT, would very much like to see a powerhouse on one of those designs.

My sketches are basic, and provide no actual measurement or standard airfoil. Simply concept configurations that I could hopefully have refined through this website before I take them on as projects of my own. On this bi-plane configuration I'd like to note the emergency parachute (as used in Sandlin's gliders) was as said.. used for gliders in the case of emergency. With a rotating prop located just behind the cockpit housing the chute, I can only imagine disaster should any lines get tangled or cut by it.

Furthermore, in drawing this I was not aware of how big the horizontal stab had become, though I kept it because it may become a benefit in the end (and because crayola pencils don't like to be erased very well). Again, crude, but an idea. Do whatever you like with it :gig:

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19. Jun 30, 2012

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I'm impressed Kyle, we need more young fellas like you joining aviation.

Your design concept is very good, it shows that you have a good understanding of the structural requirement, which is proper triangulation with no offsets which would create bending moments.

Your tail volume is definitely not too large, small tailfeathers is a common mistake, and in lightweight and slow flying aircraft which are subject to greater disturbance from wind and turbulence you need powerful control authority. In the ultralight arena a good rule of thumb is that the horizontal stab (HS) should be around 1/6x the area of the mainplane(s) if it is behind the mainplane 30% point by 2.5-3x the mainplane chord length, which is about what you have drawn. If the HS is further back it can be proportionately smaller and v.v.

The fin/rudder (VS) is another oft-maligned critical piece of equipment and should have a minimum of 60% the area of the HS, following the same rule of thumb.

Good stuff, keep at it!

20. Jul 1, 2012

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Re: A challenge to you all - AirToy

Well I've finally made up my mind what I am going to design, based on some of my old ideas from the early days of ultralights, and modified according to the results of some of the wonderful research and discussion that has taken place on this thread.

For two main reasons I am going to start a new thread for this project -

First, I have had some discussion with friends in the legal profession and, because of the OP’s request, if I were to do it on this thread it could be construed that whatever I put out there was intended to be 'offered' and there is a small chance that doing that could carry some liability issues with it.

Secondly, I have some fairly firm views about what I will be doing. Nothing is set in concrete of course, so I certainly invite all to provide input as it comes together, but I don't want to appear to be pushing my barrow on this thread's open design discussion, especially if someone else firms up their intentions and starts to design in a different direction.

For legal reasons I will be modelling up this new aircraft for my own purposes only, as I go about it others may want to use some of the ideas that come out of it and that is up to them of course, but I am not in any way suggesting that they do - it is a design exercise for my own amusement, nothing more.

I started by making a list of all the things I found beneficial from our research, and that and the polls are what influenced my decision about the configuration –

Taildragger – it’s lighter than tricycle and gives the aircraft more useability in terms of flying to/from unmade surfaces, and provides the pilot with the opportunity to hone their groundhandling skills.

Engine - A heavy engine means reduced performance in a category of aircraft that already has quite a restriction on its performance, so I can't bring myself to use the industrial engines, they’re not too bad with a redrive but still not remarkable. So I will be designing around the purpose-built engines, if someone builds something similar then they can use whatever powerplant suits them by making the nose longer for a lighter engine and shorter for a heavier one. I have chosen the MZ201 with 45HP at just 4500rpm, electric start and redrive for $4440 plus freight and 69lbs/31kg I don’t think I’ll find anything better, and its weight is midway between the lighter MZ34/MZ100 and the industrial V twins. A variation on the theme with minimal change to the airframe would be to have twin wing mounted engines, probably using the MZ100s for about the same price and weight or the MZ34s for a bit more of both. High wing, low wing? I like mid wing personally but the polls said high or low so I'm going for both high and low - biplane... because I have to have so much wing area just two wing panels are each very large, by stacking them one above the other the span is less for hangarage if/when it's hangared. Also the chord of each wing is less than a monoplane's would be, so the overall length of the fuselage is proportionately less, making for an altogether more compact airframe. Fuselage - those profile type of fuselages are intriguing and as PTA so accurately pointed out, surface area is the killer as far as weight is concerned; the profile type is a great way to reduce that area and therefore the overall weight. But I also like the option to have the cockpit enclosed, and the quickest way of building a fuselage is the Winton style using square box section aly - Cab Wasp* Cadet* Cadet MkIII* Ca - scroll down to 'Cricket'. So I am going to use a hybrid of all three. Undercarriage - can't beat the Drifter style and with rudder mounted tailwheel. Getting in and out of a minimalist cabin biplane is easiest by going in through the windshield like the Hiperlight , but I am going to try and avoid or at least minimise the reverse wing stagger. I think that should all be achievable for under$10K so that is my target.

I do hope you’ll come and contribute on the ‘AirToy’ thread.

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