Wing profile for thermal glider - RC Groups
Thread Tools
Dec 04, 2017, 05:19 PM
Registered User
Guizzo 17's Avatar
Discussion

Wing profile for thermal glider


Hi all! My mate and me have the intention to build two identical replicas of the Cormorano, a vintage Italian model glider.
The idea is to change the old fashioned NACA 6412 wing profile with a modern one to improve thermal gliding.
I'm not an expert on the matter and I'm asking your help.
The model has a wing span of 2 meter with a chord of 20 cm and 18 dm2 of wing area. Weight will be about 1.5 Kg.
Which modern profile would you think is a good candidate for thermal gliding?
Thanks.
Sign up now
to remove ads between posts
Dec 04, 2017, 06:11 PM
God Created me to Create
The_Builder's Avatar
Quote:
Originally Posted by Guizzo 17
Hi all! My mate and me have the intention to build two identical replicas of the Cormorano, a vintage Italian model glider.
The idea is to change the old fashioned NACA 6412 wing profile with a modern one to improve thermal gliding.
I'm not an expert on the matter and I'm asking your help.
The model has a wing span of 2 meter with a chord of 20 cm and 18 dm2 of wing area. Weight will be about 1.5 Kg.
Which modern profile would you think is a good candidate for thermal gliding?
Thanks.
What are the control surfaces?
Dec 04, 2017, 08:15 PM
B for Bruce
BMatthews's Avatar
The 6412 was thick but also has a lot of camber. So that would imply a slow floating sort of glide. Do you want to retain that? It would cost you in penetration for getting back upwind. Or are you after an airfoil which will give you a bit more speed range?

You should also be able to build any sort of 2 meter vintage glider to well under 1Kg, never mind 1.5Kg. And I would imagine that more like 700 to 800 would be very reasonable. Do you have a link to the plans or a scan of them?
Dec 05, 2017, 04:03 PM
Registered User
Guizzo 17's Avatar
Well, I see my requirements are a bit too vague and even misleading!
First,the model I'm speaking about is quite similar to the one on the following link.
https://static.erowz.com/13/pimg/0/1...DQ3_medium.jpg
Actually, it's our intention to install an electric motor on the nose and we are aiming only for leisure thermal flight so a certain amount of wind penetration is desirable.
As Bruce noted, for some reason I definitely made a great mistake saying that we are aiming for a weight of 1,5Kg. My hope is that this will be the total weight of the two models! So 700 – 800 grams is much more sensible for a single aircraft!
A model with RET is all what we desire.
Dec 05, 2017, 05:39 PM
God Created me to Create
The_Builder's Avatar
I am not sure what the T is in RET so I will go with RE and try to offer an idea. There is an obscure airfoil designed by Gerald Taylor is is designed to be flown as a RE wing. He designed it for building Polyhedral DLG's. It is not for the faint of heart as it is Thin !!! The root on the wing I just built is 185mm but only 12mm think. Your build skills need to be spot on to end up with a wing that will hold up but I believe you would find it worth the effort. If you decide to head down that path I will help where i can, the wing I built is Very stiff.

The airfoil can easily be found by doing a search in the Hand Launch forum. He called the airfoil the Poly-Hot, as thin as it is I am sure you understand why....

On the weights, Bruce is dead on. With no motor the 2M I am working on should be very close to 350 grams. The wing is only 220 grams ready to fly. An E-version of the plane I am designing would be a ball to fly !!
Dec 05, 2017, 08:54 PM
B for Bruce
BMatthews's Avatar
If you want modern performance with the look of a vintage glider than what Builder is suggesting would work like a charm. If you want to maintain a more floaty sort of glide consistent with the vintage look then you'd want something more like a Selig 4061 that focuses on a little more camber but can still move against the wind fairly well. Or perhaps split the difference with an S3021. Or simply use some of the very thin DLG airfoils.

Paul, the "T" is for Throttle. Guizzo mentioned electric power.
Dec 05, 2017, 11:33 PM
Registered User
MSelig's Avatar
This glider?

Cormorano: il ritorno (1 min 59 sec)
Dec 06, 2017, 07:57 AM
God Created me to Create
The_Builder's Avatar
Quote:
Originally Posted by BMatthews
If you want modern performance with the look of a vintage glider than what Builder is suggesting would work like a charm. If you want to maintain a more floaty sort of glide consistent with the vintage look then you'd want something more like a Selig 4061 that focuses on a little more camber but can still move against the wind fairly well. Or perhaps split the difference with an S3021. Or simply use some of the very thin DLG airfoils.

Paul, the "T" is for Throttle. Guizzo mentioned electric power.
Thanks Bruce, I did not put the two together...
Dec 06, 2017, 08:41 AM
Registered User
Guizzo 17's Avatar
Thank you all for your precious help.

Please, forgive my roughness mentioning “RET” in this forum. I should have known it is an alien term among the purists of thermal flying!

Yes, MSelig! That's the beast we want to reproduce! This was in our dreams when my mate and I were young. It was too expensive and difficult for us! Now we may afford the task!
It'll be a near future project and I guess we will post somewhere in R/C Groups
Dec 06, 2017, 10:15 AM
Registered User
Check Ultralajt design Vesna partial kit made by Mitija, the famous Guppy creator, could be on your liking and can be motorised.
Dec 06, 2017, 11:50 AM
Registered User
Guizzo 17's Avatar
Thanks, but we are enquiring just for a wing section, not a kit!
Dec 06, 2017, 01:29 PM
Registered User
That cormorano looks astoningly similar to Graupner`s bestseller for5 decades the Amigo.So why not use that profile? Plans are at "outerzone".Eugen
Dec 06, 2017, 02:17 PM
Registered User
MSelig's Avatar
I looked at the Graupner Amigo III airfoil from the outerzone plans site. A cropped version from the plans is below. The S4061 is also below. When I overlay these, the two airfoils are really close over the region where it matters most -> forward upper surface. The difference is near the trailing edge -- Amigo is mainly thicker -> makes it buildable. I like the suggestion above to use the S4061 for this vintage glider but with an airfoil better than the OEM NACA6412.
Dec 06, 2017, 03:49 PM
Registered User
The last time I got a "That idea is not sooo bad Kid" from such an authoroty was 30 years ago. Eugen
Dec 06, 2017, 03:58 PM
Registered User
MSelig's Avatar
When I hear that a glider has been around for 5 decades -- there's something there to look at.


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Wing profile for a 3D printed solar glider clementt Hand Launch 26 Feb 04, 2017 12:35 AM
Discussion Wing Joiners on Big Thermal Gliders? slowmatch Sailplane Talk 28 Nov 25, 2016 01:22 PM
New Product 2M D-Box Pro Wing Raptor 2000 Advance Aerobatic Thermal Glider phil alvirez Electric Sailplanes 0 Feb 12, 2016 01:55 AM
Question Profiles for Thermal Plank wings? target Thermal 19 May 24, 2012 01:53 PM
Discussion "Hang glider wing" vs real wing profile for AP kristiansch Aerial Photography 11 Feb 08, 2010 05:37 PM