Modified horizontal stabilizer?
- Thread starter cook11
- Start date
cubdriver2
FRIEND
upstate NY
Bearhawk Builder
FRIEND
In the woods
Bearhawk folks sell airfoil shaped ribs for their horiz stab, I bet you could work with those.
bob turner
Registered User
Probably have to install speedbrakes to slow down?
aktango58
FRIEND
18AA
Efficiency in control movement. Should give more force for same deflections.
Eddie Foy
MEMBER
South Florida
Why symmetrical. Tail planes on a Cub only provide lift in the down direction in 99% of normal flying.
Would make it easier to raise the tail though.
Mark_Moyle
SPONSOR
Platinum
Air foil shape also has less drag than a flat stabilizer.
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Eddie Foy
MEMBER
South Florida
Bill Rusk
BENEFACTOR
Sandpoint, Idaho
Javron can do it. I think if it was a significant improvement you would see it more commonly on Cubs. But you rarely see it so I don't know that it's a significant improvement. Personal opinion. It is going to add weight, and if it's not making any noticeable improvement, why add the weight? It is required when you use the Keller flaps, and that is about the only reason I think you see it. In that particular application it helped reduce feedback in the stick from the horizontal stab elevator combination when the flaps were extended.
Just my opinion
Bill
Just my opinion
Bill
Mark_Moyle
SPONSOR
Platinum
Dave Calkins
Registered User
Anchorage, Alaska
"Required" ? Not sure about that comment Bill.
Do we have an answer from Doug whether it is a stall buffet from the tailplane or a burble rolling onto the tailplane from the flap flow? Would be nice to know.
Bill Rusk
BENEFACTOR
Sandpoint, Idaho
Dave
I was wrong to use the term "required". It looks like it may be required IF it gets "certified" with an STC. I have flown three Cubs with the Keller flaps, all without the modified tail, and it flies great though you can feel the stick shake when the flaps are deployed.
If you go here.......Doug Kellers Website........ http://www.performancestol.com/faqs/
Parts 9 and 10 address the interaction of the modified Horizontal Stabs relative to the flaps.
9. I heard that the prototype aircraft has a stick shake. Is that true?
The prototype aircraft did have a slight stick shake at slow speed prior to a stall. We designed and built a new replacement stabilizer to replace the existing Cub stabilizer and the shake was eliminated. The stick shake is only a problem for certification.The prototype flaps have been flown over 100 hours with over 30 different pilots with the stock stabilizers, and no one has commented negatively about the stick shake other than DER test pilots. The new stabilizers eliminate the stick shake in support of FAA certification requirements. It is our opinion that Experimental users will not require the new stabilizers. However, if after purchasing the flap system you decide that you would like the new stabilizers as well, you will be able to purchase them separately. We are currently working on the production tooling and pricing for the new stabilizers and will post pricing soon. See the picture of the new style stabilizers in the gallery section.
10. Do I have to have the Stabilizer to fly with the new flaps safely?
The Stabilizer is a personal choice. It is our opinion that it is not necessary to have the Stabilizer on your experimental airplane to fly safely and optimize your STOL experience. You can choose to purchase a Stabilizer at a later time, if you feel you want/need it. We are currently establishing manufacturing costs. Availability and pricing available soon.
Hope this helps
Bill
I was wrong to use the term "required". It looks like it may be required IF it gets "certified" with an STC. I have flown three Cubs with the Keller flaps, all without the modified tail, and it flies great though you can feel the stick shake when the flaps are deployed.
If you go here.......Doug Kellers Website........ http://www.performancestol.com/faqs/
Parts 9 and 10 address the interaction of the modified Horizontal Stabs relative to the flaps.
9. I heard that the prototype aircraft has a stick shake. Is that true?
The prototype aircraft did have a slight stick shake at slow speed prior to a stall. We designed and built a new replacement stabilizer to replace the existing Cub stabilizer and the shake was eliminated. The stick shake is only a problem for certification.The prototype flaps have been flown over 100 hours with over 30 different pilots with the stock stabilizers, and no one has commented negatively about the stick shake other than DER test pilots. The new stabilizers eliminate the stick shake in support of FAA certification requirements. It is our opinion that Experimental users will not require the new stabilizers. However, if after purchasing the flap system you decide that you would like the new stabilizers as well, you will be able to purchase them separately. We are currently working on the production tooling and pricing for the new stabilizers and will post pricing soon. See the picture of the new style stabilizers in the gallery section.
10. Do I have to have the Stabilizer to fly with the new flaps safely?
The Stabilizer is a personal choice. It is our opinion that it is not necessary to have the Stabilizer on your experimental airplane to fly safely and optimize your STOL experience. You can choose to purchase a Stabilizer at a later time, if you feel you want/need it. We are currently establishing manufacturing costs. Availability and pricing available soon.
Hope this helps
Bill
I am reluctant to reply to this in fear of getting reprimanded by the site host, but I will take the bait.
The airfoil stabilizers are not required for the Double Slotted Flap STC which we expect to be granted any day now. The airfoil stabilizers do provide a tremendous benefit by adding additional elevator authority and greatly reducing the amount of elevator trim used throughout the the flight and CG envelope. It is interesting that people makes bigger elevators to increase the elevator authority, if you really want more elevator authority, add airfoil stabilizers. There is not much weight gain if any. We elected to not certify them with the flaps because our DER test pilot and the FAA did not deem them necessary for the flap certification. We also wanted to do everything we could to reduce costs and simplify the STC installation. We are considering certifying them at a later date because they add so much benefit. Jay of Javeron does build them for us, you can not buy them directly from Javeron, you will have to go through Performance STOL to get them.
Performance STOL will be at the Alaska Airman's show this year, if all goes well we will have our PMA by that time and will be able to sell certified flaps at that time. No promises, the FAA is in control at this point.
Doug
The airfoil stabilizers are not required for the Double Slotted Flap STC which we expect to be granted any day now. The airfoil stabilizers do provide a tremendous benefit by adding additional elevator authority and greatly reducing the amount of elevator trim used throughout the the flight and CG envelope. It is interesting that people makes bigger elevators to increase the elevator authority, if you really want more elevator authority, add airfoil stabilizers. There is not much weight gain if any. We elected to not certify them with the flaps because our DER test pilot and the FAA did not deem them necessary for the flap certification. We also wanted to do everything we could to reduce costs and simplify the STC installation. We are considering certifying them at a later date because they add so much benefit. Jay of Javeron does build them for us, you can not buy them directly from Javeron, you will have to go through Performance STOL to get them.
Performance STOL will be at the Alaska Airman's show this year, if all goes well we will have our PMA by that time and will be able to sell certified flaps at that time. No promises, the FAA is in control at this point.
Doug
cubdriver2
FRIEND
upstate NY
I'm I missing something? I kinda like a little stick shake just before the stall
Glenn
Glenn
The reason I am asking is that I am looking into possibly installing slats and enlarged flaps on my experimental Pacer and I have read/heard that some SC pilots install a horizontal stabilizer which has an airfoil to it which can give more authority at slower speeds. I am curious to know how a Pacer with a SC horizontal stabilizer that has an airfoil would perform
Jonnyo
Registered User
Fairbanks, Ak
Great question Glenn.
Does the shake happen just before the stall?
What angle of attack does it start?
With slats, and Keller flaps: What angle of attack does it start?
Dave Calkins question is also spot on.
Is the shake a "stall buffet from the tailplane or a burble rolling onto the tailplane from the flap flow"?
Does the shake happen just before the stall?
What angle of attack does it start?
With slats, and Keller flaps: What angle of attack does it start?
Dave Calkins question is also spot on.
Is the shake a "stall buffet from the tailplane or a burble rolling onto the tailplane from the flap flow"?
Steve Pierce
BENEFACTOR
Graham, TX
I have experienced stick shake in a couple of Super Cubs and believe it to be a burble, not really close to the stall.
