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Mr_Avocado

New Member
Joined
Sep 29, 2020
Messages
3
Greetings,
I have recently moved an ultralight airplane design project from a back of the napkin sketch to a more legitimate design. Because I have less experience than others on this site, I am trying to keep the design simple and easy to build, as to increase the ease of construction, as well as bring the construction cost down.

With these in mind, I have decided on a riveted aluminium tube construction method. The fuselage is based off of a Russian ultralight I found recently, called the X-12h. Not very much information is available about this airplane, but sources claim that it was able to be broken down to fit in a suitcase. The X-12h is a very small airplane, with a length of 3.74 meters and a wingspan of 6.31 meters. My design is larger than this, with a length of 20.33 feet (6.19 m), and a wingspan of 22.25 feet (6.78 m) My design also has a much longer wing chord, and more wing area.

While I have the general form for the fuselage down, I do not have the method of attachment between tubes down. As of right now, I am leaning towards the idea of 4130 steel gusset plates. Having never worked with this, I would appreciate some insight into how this would look. Would I need multiple for each connection? What thickness of metal would I need? I also had the idea of cutting the tube itself to create 'flaps' on the end of the tube that could then be riveted to the adjacent tube. The size of tubing I am planning on using is 1" x 0.09" 6061 round tube.

The wing configuration is a wire braced mid wing. The wing is wire braced using 3/16" wire rope, which should be more than enough. The wing is similar in construction to the Affordaplane wing. It utilizes a 2" x 0.125" leading edge, a 1.5" x 0.125" trailing edge, and wing ribs made up of 0.5" x 0.058" tube. The airfoil is the Clark YM-15, and has a chord of 4 feet. As for covering material, I feel that Oratex fabric would be adequate. I am considering using Polycarbonate coroplast to cover the wings, because this is a cheaper material. If anyone knows anything about the use of this material, I would love to know. Another thing I have been considering is a single surface wing. I have not seen much data on the use of single surface wings on ultralights, other than on the Quicksilver.

The wing connects to the fuselage by attaching directly to the wing root, which is permanently attached to the fuselage. If any of you have seen Peter Sripol's first ultralight, the wing root to wing connection will look very similar. The wing itself has 5° of dihedral past the wing root for stability.

I am yet to decide on an engine, other than it will be a gas engine in the 25-50 hp range. The engine itself will not be in line with the propeller, and will use a custom belt or chain reduction drive to run the propeller.

That is pretty much all I have at this point! If you see any errors in my work, or things that might work better, please let me know!

(For the 3-view drawing- 1" tube is the black line, exceptions being the leading and trailing edge of the wings. yellow is 0.5" tubing. Red on the wing shows where there will be both a top and bottom rib. Yellow only means only a top rib. Green outlines where the propeller will be, and purple outline where fuel and the engine will be.)

 

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D_limiter

Well-Known Member
Lifetime Supporter
Joined
Jul 13, 2018
Messages
113
Location
Norcal
Welcome! Thanks for telling us about your project. You may want to explore the various sub forums devoted to each issues you decribe above. Start with the search functions, and then pick the brains of the forum.

As for your gussets, I’m not very experienced, but to prevent galvanic corrosion, you may need to keep the gussets aluminum.
 

Mr_Avocado

New Member
Joined
Sep 29, 2020
Messages
3
Good start.
May I suggest lenghthening the tail moment arm to improve yaw and pitch stability?
Thanks for the suggestion! In the modified design, it is lengthened by 2 feet. Would this be sufficient? Is there any good rule of thumb for how long this component should be?
 

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don january

Well-Known Member
Log Member
Joined
Feb 10, 2015
Messages
2,852
Location
Midwest
Welcome to the forum and may I suggest that you just get a set of prints for the PDQ-2 and build it instead. Its pretty much the same plane as your wanting to build but a proven aircraft already.
 

BBerson

Light Plane Philosopher
HBA Supporter
Joined
Dec 16, 2007
Messages
13,757
Location
Port Townsend WA
The drawing shows a cable braced wing attachment point about two feet from fuselage side. That will not work.
The wing attach spar bolt must be at the fuselage side post.
 

Speedboat100

Banned
Joined
Nov 8, 2018
Messages
1,466
Location
Europe
There are few good books to calculate the tail volume...Roskam's book ( aeroplane design ? ) is one book to load.
 
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