Source for Gurney material?

[EricP]

I need to replace the Gurney pieces on the trailing edges of my front and rear wings. The only stuff I can find at McMasterCarr or the local hardware is 1/16th thick. That seems thick given what I’ve seen and what is on there is about half that. I’ve searched but haven’t found a definitive answer. Where does everyone get theirs?

Also, mine were bolted on with tiny button head allen screws. Some folks mention tape. What kind of tape? That doesn’t rip off!?

[ianashdown]

I have made many using prepreg carbon using two Aluminum angles as tools. You could use wet resin, fiberglass and a vacuum bag just as easily.

Ian

[DaveW]

90-deg angles 0.04" wall, 1/4 and 5/8 width & height

https://www.mcmaster.com/#8982K1

https://www.mcmaster.com/#8982K2

[BorkRacing]

Home Depot

[Steve Demeter]

Would not suggest using tape. The button head crews will work fine and you can have diffeent height wickers made up ad change them quickly.

[David Locke]

I used clear plastic wall corner guards from Lowe's, cut to various heights, and attached to the surface with clear leading edge tape.

[EricP]

90-deg angles 0.04" wall, 1/4 and 5/8 width & height

https://www.mcmaster.com/#8982K1

https://www.mcmaster.com/#8982K2

Thats embarassing. I searched 3 times and never saw that! Thx

[stownsen914]

Bumping this back up as I have the same question. I'm not finding obvious ready made options by googling. Do folks usually just make their own using aluminum (or carbon) stock? I'm looking for a 1/4" gurney, ideally with 3/8" to 1/2" on the other leg. 68" long.

[lowside67]

I imagine it narrows your material choice very considerably if you are looking for unequal leg lengths. I'd think most live with either a smaller mounting flange or larger gurney flap in order to have ease of selection.

If you were inclined, you could also use an off the shelf piece of angle iron as a mold and make your own CF angle to achieve the asymmetrical sizing.

-Mark

[LarryWinkelman]

Try Kevin at Comprent. He sells 1/2 x 1/2 and 1/2 x 1/4 carbon fiber gurneys for the FE and ESR.

[BorkRacing]

Bumping this back up as I have the same question. I'm not finding obvious ready made options by googling. Do folks usually just make their own using aluminum (or carbon) stock? I'm looking for a 1/4" gurney, ideally with 3/8" to 1/2" on the other leg. 68" long.

Your .25"x.375" gurney lives inside a .375x.375 piece of L angle aluminum.

Cut it or apply it to the bottom of your edge.

[Rick Iverson]

Gents;

I recall a post of mine where there was a pictorial of Gurneys both top and bottom. Thoughts?

[alangbaker]

Your .25"x.375" gurney lives inside a .375x.375 piece of L angle aluminum.

Cut it or apply it to the bottom of your edge.

Gents;

I recall a post of mine where there was a pictorial of Gurneys both top and bottom. Thoughts?

Since the whole purpose of the gurney flap is to create a small low pressure area that will help keep the flow attached to the underside of a wing:

1. Don't put one top and bottom.
2. Don't attach it on the bottom side and create turbulence precisely where you're trying to keep the flow attached.

I'm not an aerodynamicist, so take with as much salt as required.

[problemchild]

I have used tin snips to cut 1/2 x 1/2 down to 1/4 or 3/8. Taping them on (electrical tape) works just fine if you want to test multiple lips on the fly. It is surprisely effective, You definitely do not want to put them on the bottom.

[BorkRacing]

I have used tin snips to cut 1/2 x 1/2 down to 1/4 or 3/8. Taping them on (electrical tape) works just fine if you want to test multiple lips on the fly. It is surprisely effective, You definitely do not want to put them on the bottom.

My advice to put them on the bottom meant to still have gurney facing up but to use the thickness of the wing to take up some of the width. While not the best approach as the edge will cause some separation of the airflow, for someone who does not have the facilities to trim metal it could be an option.

[Lotus7]

My advice to put them on the bottom meant to still have gurney facing up but to use the thickness of the wing to take up some of the width. While not the best approach as the edge will cause some separation of the airflow, for someone who does not have the facilities to trim metal it could be an option.

I fear the negative effects of the gurney under the wing will offset much of the desired gains, leaving you with simply a drag device. YMMV, try it and see?

[BorkRacing]

I fear the negative effects of the gurney under the wing will offset much of the desired gains, leaving you with simply a drag device. YMMV, try it and see?

I think the try it and see is sound advice.
We don't know how tightly attached the boundary layer is, if there are any screw heads or seams causing turbulance etc.

We do know that as angle of attack is increased ( or decreased for our use) the separation of the boundary layer increases and moves forward. So a small 1-2 mm high object may upset the airflow or be inconsequential.

Logic usually prevails but in aero it's a whole new type of logic. Take taping body seams. Tunnel data has shown in some cases the bump between seams made for smoother airflow of the boundary layer. Or it would seem the smoother the surface the better the airflow but current data shows a micro "golf ball" surface is better.