FTFC20 Guillows #303 Super Cub designed by Mr. Gandalf

[Mr. Gandalf]

This is the first forum challenge I will have participated in and I am very excited to get started, but first here is some history of the balsa model!

The balsa kit was pretty small with a wingspan of 24". Designed for rubber powered free flight, or control line with a glow engine, It was built with traditional stick and tissue techniques and designed with scale realism in mind resulting in a very good looking model. However this is a picture of mine after having the nose rebuilt.

I chose these plans because I already had them laying around, and because the balsa kit that goes with them was my first RC plane (which was quickly replaced by a mini simple cub). I am going to use a mix of master series and regular flite test techniques to build the foamboard model which will be 4ch (possibly flaps) and have a 40" wingspan.

My method for converting the balsa plans to foamboard is very low tech, I just trace the patterns for the sides of the fuse, wings, and tail feathers and blow them up using my printer, but the nose will be done using trial and error.

More updates soon!

 

[Mr. Gandalf]

Reserved for flight video.

 

[Mr. Gandalf]

Reserved for plans.

 

[Mr. Gandalf]

I have already made some good progress since I started yesterday!



The main section of the fuse just uses a B fold, and the H stab has some slots that slide into the tail. Next, some formers are set and the power pod slides through the holes in them and is glued in place. Then, the skin is wrapped around the formers and glued flush with the front of the main fuse.

That's all I have for now, I think the cowling will be the next piece to be tackled. The rest of the design is pretty well planned out in my head, but the one thing that I'm wondering about is how I will attach the wing, right now I am thinking it will be a two piece wing.

More updates soon!

 

[rockyboy]

Welcome to the challenge!

One method I've liked for two piece foam board wings is to use fiberglass arrow shafts as wing spars and leave enough sticking out of the wing root to fit into a matching tube on the fuselage.

 

[Mr. Gandalf]

Welcome to the challenge!

One method I've liked for two piece foam board wings is to use fiberglass arrow shafts as wing spars and leave enough sticking out of the wing root to fit into a matching tube on the fuselage.

Thanks!

That's what I was thinking too, but I was also thinking of making the wing removeable and doing it in an easily repeatable way, so I guess that the real problem is securing the wing without gluing it on.

 

[rockyboy]

Thanks!

That's what I was thinking too, but I was also thinking of making the wing removeable and doing it in an easily repeatable way, so I guess that the real problem is securing the wing without gluing it on.

Pins & bolts or rubber bands are the two most common ways I have seen it done

 

[Mr. Gandalf]

I am going to do more research before I decide on anything, but thanks for the suggestions!

Now that I think about it, a 40" wingspan may be small enough to not need a removeable wing.

 

[Mr. Gandalf]

Finished the cowling, windscreen, and got the wings built!

Here's the mockup!



There were no markings for ailerons on the plans, so these are totally improvised, but I think they should do fine.

 

[Mr. Gandalf]

Made plenty of progress on the super cub! I got the landing gear built and installed, added wing struts, put in the electronics, and designed a new windscreen/hatch.


AUW is about 13oz, I am using a small motor and a single 450mah battery, but there is plenty of room for a bigger one. Some problem solving was required to get the motor in the right spot, so a swappable mini powerpod is used to make the motor's position adjustable.

I tried to maiden it last weekend but it was really windy and I was experiencing some technical difficulties with my motor. However, the maiden should be soon!

 

[TooJung2Die]

How did I miss this? All you have to do is say Guillow's to get my attention. Great work so far. The bigger the better. I like the Guillow's 300 series. I have a micro Rx brick and gearbox motor ready to go into one of these if I can decide which one to build.

 

[Mr. Gandalf]

How did I miss this? All you have to do is say Guillow's to get my attention. Great work so far. The bigger the better.

Thanks! I am planning on doing some more Guillows R/C conversions myself once I feel like my piloting skills are up to it.

I like the Guillow's 300 series. I have a micro Rx brick and gearbox motor ready to go into one of these if I can decide which one to build.

How about the Piper Cherokee?

 

[TooJung2Die]

How about the Piper Cherokee?

Except for the Cherokee. Or the Beechcraft. Both are low wing. The high wing scale models are more stable in flight. If I'm going to spend months building an airplane I want all the in flight stability I can get.

 

[Mr. Gandalf]

Have some propellers coming in the mail, so I should have a maiden by this weekend.

 

[Mr. Gandalf]

Had some problems with the propellers so I didn't get to fly the super cub until today, but I'm not sure if you can call what happened a successful maiden flight.

I will post pictures and video later.

 

[Mr. Gandalf]

Well, not much to say but, I'm super happy it flew, and It needs some work!

The ailerons seemed mushy, as in I would move the stick and it wouldn't respond immediately, and it took a ton of rudder to make it turn.

Here's the damage, I am just going to build a new one because this one clearly has some problems.

 

[Mr. Gandalf]

I just got back from flying the super cub. Before building a new I decided to make improvements to this one and see how they worked, the changes I made were: increasing the size of the rudder to 110%, lengthening the ailerons, and beefing up the landing gear.

Unfortunately I was unable to get video. Although it did fly and the ailerons' mushiness was fixed, it was difficult to turn so I ended up crashing it. I think the problem now is just the control surface throws, so once I get that right it should fly well!

 

[Mr. Gandalf]

Super cub V2!

 

[Mr. Gandalf]

Unfortunately, I have had almost no success with flying this design. It was so frustrating that I put it aside to fly and work on other projects, but I might return to it in the spring or summer.

 

[Tench745]

I notice that you're using a molded eliptical wingtip style. From the flight videos I saw I suspect this is part of your trouble. Much of the unpleasant flight characteristics appeared to be in a high angle of attack, and I believe that your wingtips are stalling. Extending your ailerons further toward the fuselage put more area in an unstalled portion of the wing further increasing their effectiveness.
I think that either building some wash-in to the wingtips or making them under-cambered like the FT Spitfire will help a great deal with this aircraft's flight characteristics.