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My funky noob tandem wing(flies!)

Vimana89

Well-known member
#1
While brainstorming and waiting for parts for my slender delta, I decided to try a quick and dirty yaw and yank tandem wing build. Took me about 3 and a half hours, and best of all, it flies! I just have to learn to fly it and keep it airborne for more than like 15 seconds.
 

Vimana89

Well-known member
#4
Too dark now, will pick up tomorrow. I know the design works, just have to learn to fly and probably make small adjustments to things like control surfaces and maybe thrust angle as I go and see where there's trouble handling. If I smash this one up, I can rebuild again and take my time with attention to detail. It's a simple build with a lot of lift and stability that doesn't fly very fast, good to learn on. I may buy a new power pack for my delta, so I can have both on deck to work with and perfect. It's nice to see one of my designs do more than flop-I think I'm over the biggest hurdle and things can only get better from here on out!
 

Vimana89

Well-known member
#6
Crashed today it has a strong tendency to pitch down and roll a bit right. I think my thrust angle is a bit too severe and my cg may be a bit far forward. Will lessen severity of thrust angle and move the battery and cg back a bit.
 

Vimana89

Well-known member
#8
That looks very cool.
Thanks, I really like the tandem wing design. if I can get this one to fly right I'll train on it until its too busted up and rebuild a more precise, permanent one. This one's a bit sloppy. The next one will be as precise as I can get it with a better more enclosed fuselage, and more precise control surfaces. I'm using this quick build one to get the cg and thrust angle right and learn to fly a bit before putting in the effort to make a really nice one.
 

Vimana89

Well-known member
#9
Flew much better with cg further back and thrust angle severity toned down a hair. I need to learn how to fly better, had to cut it short because it was headed towards somebody's yard. This plane has no structural integrity, my fault for building it that way, just can't take a hard landing. At least I know the design is sound, I'm just going to have to take my time on the rebuild.
 

Vimana89

Well-known member
#11
Ok. Pretty broken for now, giving it a rest.will rebuild some time when I have the time to really make it nice and strong. The problem I'm having is that I just can't get her to climb and maintain flight or altitude even when I increase throttle and pitch. It could be my thrust angle or cg, or maybe my control surfaces don't have enough authority. Thing is, it's hard to keep trying to figure it out if my plane can't take a rough landing and I have to walk back and repair after every launch.
 

Vimana89

Well-known member
#12
Rough draft had one last go in her, was able to gain a bit more altitude and fly farther, but I tried to yaw using the rudder and it rolled and crashed. Front end is totally smashed and split, but no big deal. Anyone have any idea why my plane rolled and crashed instead of turning? I'll be taking my time and doing some research, watching some vids on how to build better before trying again. I have a feeling some of my issues are having a semi-open fuselage where airflow can be trapped at funky angles, so I will be building a proper enclosed fuselage with some way for me to access the battery. I will also most likely purchase some nice proper push rods with the little pivoting connector thingies and some proper control horns that aren't a zip tie. I have to get those control surfaces right to where they have enough authority but aren't overly responsive. If anyone has any tips or advice, I'd be more than happy to hear it.
 

Hai-Lee

Old and Bold RC PILOT
#13
With a tandem design it can be configured for control in a number of different ways.

You have the choice of elevator function on the forward wing with the ailerons on the rear wing, the reverse, or only one wing pair having elevon type control.

Rudder usage needs to be treated gently as you have 2 wings that will slow, on one side whilst 2 wings will speed up on the other side when the plane yaws. In addition the change in wing speeds is not uniform from front to rear so a serious roll moment can develop very quickly especially if the plane is flying at very slow speeds. wing stalls are quite common in a sharp rudder turn!

Final recommendation is to have the forward wings low on the fuselage and the tail wings above the fuselage to enable the interference between the wings to be minimised. In addition you may require a very slight increase in the rear wing incidence angle if the plane is to be flown at higher speeds or is rather heavy.

If you need any further help to overcome aerodynamic issues that you may encounter please advise and I will see if I can assist in a workable answer!

Nice project with plenty of promise.

Have fun!
 

Vimana89

Well-known member
#14
With a tandem design it can be configured for control in a number of different ways.

You have the choice of elevator function on the forward wing with the ailerons on the rear wing, the reverse, or only one wing pair having elevon type control.

Rudder usage needs to be treated gently as you have 2 wings that will slow, on one side whilst 2 wings will speed up on the other side when the plane yaws. In addition the change in wing speeds is not uniform from front to rear so a serious roll moment can develop very quickly especially if the plane is flying at very slow speeds. wing stalls are quite common in a sharp rudder turn!

Final recommendation is to have the forward wings low on the fuselage and the tail wings above the fuselage to enable the interference between the wings to be minimised. In addition you may require a very slight increase in the rear wing incidence angle if the plane is to be flown at higher speeds or is rather heavy.

If you need any further help to overcome aerodynamic issues that you may encounter please advise and I will see if I can assist in a workable answer!

Nice project with plenty of promise.

Have fun!
Thank you, I appreciate all the help I can get. Very good point about having the forward and rear wings at different height because of air flow interference, most tandem builds I have seen have been set up that way, though there is a video that sort of inspired my build of somebody flying a tandem wing rc in strong winds with level wings. This person has an airfoil on his wings, and an overall cleaner and better build, but the wings are on the same axis of height.


That being said, what you suggested is probably the better route, and would be a very easy change to make to my build.
 

Hai-Lee

Old and Bold RC PILOT
#15
Believe it or not a pusher design is normally better for predictable performance if using undercarriage and a ground run take off.

You should search for the "Flying Flea" tandem wing design to see some of the extreme handling problems if you get the design wrong!

Have fun!
 

Vimana89

Well-known member
#16
Believe it or not a pusher design is normally better for predictable performance if using undercarriage and a ground run take off.

You should search for the "Flying Flea" tandem wing design to see some of the extreme handling problems if you get the design wrong!

Have fun!
I could perhaps adapt to a pusher, although my design was hand-launched and had no landing gear. Pushers are less likely to get smacked up and don't require a thrust angle, so that's good, but on the down side require your electronics to have the right length if at the rear, and require clearance for the prop if anywhere else.
 

Hai-Lee

Old and Bold RC PILOT
#17
As with all things start with what you have working and only change it a little at a time to develop your design rather than start over building someone else's design. Try making a single change, SAY perhaps the split level wings first and judge if it is better or worse before moving on to any other changes.

just a path to proceed, but as usual do as you wish in your own time!

Have fun!
 

d8veh

Well-known member
#18
I agree. You're on the right track, but you have to sort out your piloting skills as well as the plane. The plane is close. If the G-spot is more or less right, the control surfaces move and the motor pulls, it'll fly. If you get those things exactly right, it'll be easy to fly.