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Olibuilt 's New Cub project

Oli, How is that tip plate held on? What does that tip rib look like? Do your spars go to the tip with the full height? My suggestion is that you make a full sized airfoil shape extension of about a foot or a little more. Attach it to the ends of the spars and to the tip rib. Then put whatever you want for a tip on that. You're a clever fellow, you could probably knock a pair out in a couple of days. You could gain as much as 300 pounds of lift with this.
 
The actual wing "tips" are held by screws into the last stamped rib. Spars are full length, 17' long, to the tip.


I like my aileron right to the tip of the wing. I don't want an "extended" wing.







But a small wingtip would be a good idea if you think the weight-lift-drag ratio is good.
 
He is not worried about hard braking on touchdown.:lol: I wish I could touch down the tail as soft as you guys do, my poor tail spring takes a beating when my transition to the mains is off. For tips how about the older droop tips like Jerry Bur runs?
DENNY
 
Olibuilt said:
The actual wing "tips" are held by screws into the last stamped rib. Spars are full length, 17' long, to the tip.

I like my aileron right to the tip of the wing. I don't want an "extended" wing.

But a small wingtip would be a good idea if you think the weight-lift-drag ratio is good.
Click to expand...
Oli, Of course it is your plane, whatever you prefer is the right thing.

The higher pressure air under the wing flows outward around the tip forming a spiral twisting action. This air pushes downward on the top of the most outboard trailing section of wing with unstable air. As a result when the aileron goes to the tip as yours does, the outboard few inches becomes ineffective. When you extend the wing the amount which I have suggested your aileron becomes more effective. This is in addition to the five or so extra square feet of lifting surface plus the improved performance of a higher aspect ratio wing. The higher aspect ratio will reduce stalling speed, increase rate of climb and in some cases increase cruise speeds in addition to improved high altitude performance.

The plates which you have on your tips would be more effective if they extended below the wing, effectively acting like a dam preventing the outward flow of air.

I did this on one of my airplanes with the idea that if I wasn't happy with it, it could be easily removed. 35 years later the extensions are still on the plane. You mentioned that you were itchy for a project, well here is one.
 
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Oli you have a very good performing cub and you know how to fly it! Do you think slats are the best wing mod
for slowest flight and slowest touchdowns?
Denny, when we installed a T3 on the S7 the AOA actually improved a bit. Should be the same with a cub(?)
T3 worth every nickel.
 
Oli,

If you’re thinking about an experimental wingtip, maybe you could incorporate a hoerner-style underside profile?

53.jpg


tCddl.png


You’d gain not only the additional actual wing square footage, but also some effective area as well. That should help you slow down some more. Might also help increase your cruise due to the decreased wing loading.
 
skywagon8a said:
Oli, Of course it is your plane, whatever you prefer is the right thing.

The higher pressure air under the wing flows outward around the tip forming a spiral twisting action. This air pushes downward on the top of the most outboard trailing section of wing with unstable air. As a result when the aileron goes to the tip as yours does, the outboard few inches becomes ineffective. When you extend the wing the amount which I have suggested your aileron becomes more effective. This is in addition to the five or so extra square feet of lifting surface plus the improved performance of a higher aspect ratio wing. The higher aspect ratio will reduce stalling speed, increase rate of climb and in some cases increase cruise speeds in addition to improved high altitude performance.

The plates which you have on your tips would be more effective if they extended below the wing, effectively acting like a dam preventing the outward flow of air.

I did this on one of my airplanes with the idea that if I wasn't happy with it, it could be easily removed. 35 years later the extensions are still on the plane. You mentioned that you were itchy for a project, well here is one.
Click to expand...

?
just curious as to how many inches down you feel the fence would need to be
 
Cubdriver2
You start loosing ground as soon as that tailwheel touches, it is not much but usually but it is noticeable. The trick is to leave the ground with letting it touch. That is why guys are pulling the wheel completely and putting on scrub pads.
DENNY
 
Skywagon
That is great information about the aileron. I could not figure out why the Cessna guys never complained about the Wing-X mod and aileron.
DENNY
 
DENNY said:
Cubdriver2
You start loosing ground as soon as that tailwheel touches, it is not much but usually but it is noticeable. The trick is to leave the ground with letting it touch. That is why guys are pulling the wheel completely and putting on scrub pads.
DENNY
Click to expand...
That was for cubdriver2. Hopefully he understands cause it’s Greek to me lol.
 
RoddyM
I looked at some S7 pics, Pretty sure your spring is not off a pa18, it looks pretty tall. With the same wheel the T3 will set the tail taller than even a 4 leaf pa18 spring set. For fly in stuff I use a 3 leaf with stock tailwheel, for off-field stuff it is a 4 leaf with a big tailwheel.
DENNY

EDIT; not enough coffee this morning, just trying to keep replys straight.
 
Olibuilt said:
But a small wingtip would be a good idea if you think the weight-lift-drag ratio is good.
Click to expand...
6E88AEDB-AF7F-42E5-9FDB-97A5CEA89AD4.jpg
Oli, As has been said, adding wing area is as good as your gonna get for adding extra lift. I added 2’ carbon fiber extensions, slowed the roll rate a bit ,So I incorporated spoiler boards to get it back. Just under 20 square ft. Of extra area was added , Made an awesome difference on the slow end. Is an easy add on with limited moding required, Especially since your spar runs the length of your wing.
Next, Obviously big honking flaps will make a difference on the drag for them slow approaches!
 

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Thank you all for your advice.




skywagon8a said:
As a result when the aileron goes to the tip as yours does, the outboard few inches becomes ineffective.My suggestion is that you make a full sized airfoil shape extension of about a foot or a little more. Attach it to the ends of the spars and to the tip rib. Then put whatever you want for a tip on that.
Click to expand...

My plane is already very tight in my hangar... I cannot add another feet per wing, unless it was quick attach :idea: ?

But you guys have sold me on wing tips. The one I have were suppose to be temporary.






Let say I think my ailerons are effective enough, not being use at slow speed anyways.
? Does a small regular Hoerner tip would do about the same, with all the way to the wing tip


Like this small Dakota

IMG_7310-768x5122.jpg
 

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Oli, Take a look at Backcountry's wing tips. http://www.supercub.com/ They would give you a bit more wing area without extending the span very much. The extra area aft would help with controlling the swirling vortex at the trailing edge.
 
Instead of quick attachment just make them hinged and folding You’d only need a lock on top or the bottom depending on which way you make it fold.


Sent from my iPhone using SuperCub.Org
 
Good idea mike, A piano hinge along the bottom and three dzus or cam-locks along the top. Some gasket material in the joint or some other method of minimizing some airflow in the joint.
 
DENNY said:
Cubdriver2
You start loosing ground as soon as that tailwheel touches, it is not much but usually but it is noticeable. The trick is to leave the ground with letting it touch. That is why guys are pulling the wheel completely and putting on scrub pads.
DENNY
Click to expand...

A tailspring might compress an inch if you over rotate and touch the TW. The T3 will compress about 5 or 6" allowing your tail to get lower and allowing the wing to get to a greater AOA then just sitting there static.

Glenn
 
DENNY said:
Cubdriver2
That is why guys are pulling the wheel completely and putting on scrub pads.
DENNY
Click to expand...

Look at pictures of a stock J4, the TW is mounted 3' in front of the tailpost. The lowly J4 Has more factory AOA then any Piper sold



~

Glenn
 
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cubdriver2 said:
A tailspring might compress an inch if you over rotate and touch the TW. The T3 will compress about 5 or 6" allowing your tail to get lower and allowing the wing to get to a greater AOA then just sitting there static.

Glenn
Click to expand...

tail SPRING will compress enough to bend rudder... seen may....
 
skywagon8a said:
Good idea mike, A piano hinge along the bottom and three dzus or cam-locks along the top. Some gasket material in the joint or some other method of minimizing some airflow in the joint.
Click to expand...

was more thinking actuating rod operated from trailing edge with a couple/few latches actuated from it...
 
I'm coming in a little late in the discussion but Sky convinced me I should consider droop ailerons which I did and have incorporated 8 degree droops on my wings. I also provided a way to lock them in the upper position so I can have normal ailerons should I want them. With all the improvements Oli has on his wings it may not be worthy of consideration at this point...just thought I'd throw that out for a project for next Winter.
 
Glenn
I have been trying to figure how to stick a tailwheel in the same position for the past two years. I have done a lot of internet search but this is the first time I have seen that pic. Too low for off field work but would be a fun fly-in setup (I would addd a rear skid just in case). If you compress a steel or T3 tail spring on takeoff the drag is going to cost you 10-30 feet in take off distance.
DENNY
 
A dinged rudder is a Citabria owner's mark of experience. Short gear and low AOA plus weak tail spring allow tail first arrivals prone to damage. Longer gear and Scout tail spring fixes the problem.

There was a J-4 in Fairbanks that dissolved sitting at Phillips Field in the 1970's. Nobody wanted to love it. Today they are very desirable.

Gary
 
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