Sunset 2023 - Surfer project

[thenated0g]

I have been keeping my eyes open for a project to use some of that surfboard foam i got for free at the last sunset event.

I did use some of it for my current project, My scratch build jart, but i wanted something special.

I remembered seeing this old build thread on rcgroups for a powered surfboard airplane and thought that might be fun to try and do as a glider.

Flying Surfer Dude! - RC Groups

Cool Flying Surfer Dude! Foamies (Scratchbuilt)

www.rcgroups.com

I could of course do it out of flat foam sheets i cut, but i would like to do it with an airfoil and at a slighter larger root (longer surfboard).
I think an actual airfoil shape and some surfboard graphics will make it much more surfboard like than a flat plate.

 

[thenated0g]

Heres the full scale plans. PDF attached.

 

[thenated0g]

One thing i notice right away is that the recommended CG on the flat foam version is about 30%, but i would normally do 22% for a plank. I guess i could set it up to try both and see what happens.

 

[Hawaii Sloper]

This is gonna be interesting!

 

[jure]

One thing i notice right away is that the recommended CG on the flat foam version is about 30%, but i would normally do 22% for a plank. I guess i could set it up to try both and see what happens.

Sounds good for a small aspect ratio wing .
For example , 25% is used in the nutball.

 

[thenated0g]

The one thing im not sure about is both the nutball and this original surfboard are powered. Meaning the motor is pulling it thru the air and usually with the nose more up. I have a feeling im going to want that 22% (more nose weight) for unpowered flight. I will definitely make a spot for adding/removing weight and a dummy "surfer" (ie not great looking) on top while i figure out cg.

 

[Hawaii Sloper]

The one thing im not sure about is both the nutball and this original surfboard are powered. Meaning the motor is pulling it thru the air and usually with the nose more up. I have a feeling im going to want that 22% (more nose weight) for unpowered flight. I will definitely make a spot for adding/removing weight and a dummy "surfer" (ie not great looking) on top while i figure out cg.

Lol! Remember one of your first builds was a nutball! That thing was sketchy… you’ve come a very long way
KP

 

[gp49]

@thenated0g

Just make it more interesting, and flyable on slope, and add some variable sweep wings popping out of the 'surfboard 'fuse'. RG15 airfoils should get you going in the right speed direction..

 

[Red]

Gonna be cool!

Red

 

[thenated0g]

f14 style lol

 

[thenated0g]

@Red yeah if nothing else it will look cool sitting up on the dunes at sunset lol

 

[Doc J]

Absolutely, certifiably, stark, staring, bonkers...In other words extracting the most amount of fun possible!

I LOVE IT!

Doc.

 

[thenated0g]

I have been thinking about and working on the design of this off and on. Finalized the dimensions at 1.8 meters / 72 inches from nose to tail. So within range of a normal surfboard for a kid. That makes the surfer come out at around 30" tall kneeling down. Probably hardest part was finding an appropriate surfer. Both aesthetically and mechanically. I found this nice one with the model having a knee down so that will help reinforce that whole area. Also on the diagram below you can see the "standard" planks CG i would set at 22% and the powered models high alpha cg at 31%. Ill probably aim for the 22 on maiden. I will for sure have some dummy weights at the two positions the surfer mounts so i can maiden it without the surfer to save on them getting damaged on first few flights.

Both the Surfer and Fin will continue into the foam into slots. Still working out the materials for them. Probably foamboard with wood, fiberglass, or carbon fiber on both sides to add rigidity. Still figuring that out. Either way its going to be a TON of weight behind that red cg line.

 

[Red]

Looks like a neat project! Don't forget to add some reflex. Low aspect ratio planks tolerate forward CG pretty well,

Red

 

[gp49]

That looks great @thenated0g ! I can see a movable surfer figure 'riding the tip' (Velcro?) to change CG and make 'easy' target replacement !

 

[thenated0g]

Thanks @Red @gp49 . Ill probably have a large slot from CG all the way to the nose to play around with different settings. Will go with a good amount of reflex and probably the opposite of normal planks on throws. IE way more elevator than aileron movement. But ill give it a lot of both for first flight.

 

[Wayne]

I always wanted to try something like this! Maybe some simple magnets to hold in the "tails" so they can pop out on a landing? Maybe just bring extras and keep them super light? You are right, they are going to be bad mass. And moving the surfer forward is not an option either.

Love it!

 

[thenated0g]

Yeah its just going to be heavy. But it also is a freaking ton of wing area at 6ft tall. Let me go figure out what that is actually.....

Ok so it comes out to 1,332 square inches or 86 dm2
So that means if it weighed 5.5kg / 200oz it would still have a 7 cubic loading (20oz wing loading), ie still considered a Sail plane/park flyer. Thats crazy heavy. I dont think my 8ft hawk weighs that much.

 

[Wayne]

Might I suggest you make it smaller? I know you love the huge planes, but they are a bear to transport and store and they are also a bit of a safety concern at Sunset. I have seen what happens when a large foam plane (even built from 1 lbs density foam) hits someone. That wing area really packs a punch. All it takes is one plane to hit your elevon and you are out of control.

 

[thenated0g]

I think i will make it same size, but how about ill make sure to maiden it before people show up or not at all if its a concern.