Using balsa plans for designing foam planes

[Heinrich Dorfmann]

Hi,As many of you know I loved trying to design small scale ,slow flying warbirds and am constantly told got to be careful about making sure the wing area / elevator/ rudder are big enough for a plane that size.
I Have been inspired to try one shape by @Mr Man after flattening problems when using fusion 360 which caused me to nearly give up designing forever.
My way of thinking is use a flyable wing already designed and tested for the size of plane you want and then just design the fuselage to be more scale .
Problem is there aren’t many below 40 inches And I need to go small as not got a lot of room.

I may have asked this before but can’t find it and have had a quick trawl through forums and it seems that it is possible to use a good balsa plan for the scale you want, to design the wing size / shape and elevator/ rudder( andpossibly even the formers for the fuselage ).Obviously the thickness is different but this seems to be a good source for potential wing/rudder/elevator sizes when drawing up plans
Eg check this 24 inches plan

https://ftforumx2.s3.amazonaws.com/2021/02/351656_03fcee6818fd71c7d7d2443c4c4e953b.pdf

looks like a really good plan,it’s got the cog on it etcetc,assuming it flew ,why reinvent the wheel?
There are literally thousands more on sites like aero Fred where people have obviously spent a lot of time producing what look like very good and useable plans.
As usual thanks for any thoughts

 

[Heinrich Dorfmann]

Have been talking with HAL and he’s been very helpful explaining how much a flyable wing can be enlarged / reduced without making any alterations,or if they do how much needs to be added to elevator/ rudder.
He also said he had made some poor decisions recently but was better now and had the greatest confidence and enthusiasm in the mission….

 

[AIRFORGE]

Have been talking with HAL and he’s been very helpful explaining how much a flyable wing can be enlarged / reduced without making any alterations,or if they do how much needs to be added to elevator/ rudder.
He also said he was better now and had the greatest confidence and enthusiasm in the mission….

LOL! And that's why they didn't get approval to call it IBM 9000 and coded it HAL.

 

[Heinrich Dorfmann]

When asked what OS I liked / preferred I always used to like to tell everyone the one I trained / cut my teeth on
- the HAL 9000 range.
Also asked HAL about using balsa plans to design a wing .My concern is that flitetest fold over wings have a flat lower surface but many balsa plans have formers which are curved underneath.
He said “
The key challenge you've identified is the difference in airfoil shape.

It's true that many balsa wing plans use complex, curved airfoils, while FliteTest's "fold-over" method is designed around a simpler, flat-bottomed airfoil.

📝 How to Adapt a Balsa Plan

· Adapt the airfoil for flat-bottom foam construction. The simplest approach is to use the balsa plan mostly for the planform (shape) of the wing, while designing a new, flat-bottomed airfoil for the ribs. This makes construction straightforward and preserves the plane's overall look and flight characteristics.
· Convert an undercambered airfoil. If your balsa plan has a classic undercambered airfoil (curved on both top and bottom), you can flatten the bottom to create a flat-bottom airfoil. This can be as simple as adding a thin foam sheet or even covering material across the bottom. This modification will increase stiffness and high-speed penetration (reducing drag) while only slightly sacrificing low-speed floatiness.
· Use balsa for structural elements. You don't have to use foam for everything. The lightweight and stiffness of balsa make it perfect for areas that experience high stress. You can keep the balsa spars, leading edges, and wingtips from your original plan.
· Build a hybrid wing. For a thicker, more complex airfoil, consider a "hybrid" approach. You can cut a series of foam ribs using your modified plan and then glue a thin top and bottom foam skin over them. This builds a very strong, lightweight wing with an accurate airfoil shape.
Anyway off to EVA pod so can talk in private without HAL overhearing. Will personally grab him by his dilithium crystals and disconnect him if he is proven wrong.

 

[LitterBug]

I'm sorry Dave. I can not do that!

 

[TEAJR66]

Thread 'RCM Trainer 5 with Ailerons' https://forum.flitetest.com/index.php?threads/rcm-trainer-5-with-ailerons.22194/