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Yak-List Digest: 13 Msgs - 02/12/08

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jacques.bodart(at)gmail.c
Guest

Posted: Tue Jun 03, 2008 3:30 am Post subject: Yak-List Digest: 13 Msgs - 02/12/08

Does anybody had done some sort of gap sealing for the ailerons of a

YAK52 or 50 like many PITTS or other aerobatic a/c to improve the roll

rate.



Concerning  the spades/shovels differences so for you the shovels are

attached to the ailerons tip and the spades are attached to the

ailerons hinges and hanging below the wing?



Many thanks



Jacques Bodart(Belgium)



On 13/02/2008, Yak-List Digest Server <yak-list(at)matronics.com> wrote:

[quote] *



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   EMail Version of Today's List Digest Archive

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           ----------------------------------------------------------

                           Yak-List Digest Archive

                                      ---

                     Total Messages Posted Tue 02/12/08: 13

           ----------------------------------------------------------

 Today's Message Index:

 ----------------------



     1. 06:10 AM - Spades  (Ira Saligman)

     2. 06:52 AM - Re: Spades  (Jan Mevis)

     3. 08:30 AM - Re: Spades  (Roger Kemp M.D.)

     4. 09:00 AM - Re: Spades  (Richard Goode)

     5. 09:36 AM - England in April  (Jon Boede)

     6. 09:36 AM - Re: Spades  (Roger Kemp M.D.)

     7. 10:05 AM - Re: England in April  (ByronMFox(at)aol.com)

     8. 11:35 AM - Trim wheel position  (John Graham)

     9. 12:42 PM - Re: Trim wheel position  (Roger Kemp M.D.)

    10. 02:27 PM - Re: Spades  (Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E)

    11. 03:07 PM - Re: England in April  (Martin Robinson)

    12. 03:29 PM - Re: Spades  (napeone)

    13. 05:35 PM - Re: Spades  (Roger Kemp M.D.)



 ________________________________  Message 1  _____________________________________

 Time: 06:10:07 AM PST US

 From: "Ira Saligman" <isaligman(at)saligman.com>

 Subject: Spades



 Is anyone familiar with putting spades on a Yak 50?

 Ira Saligman

 o   610 940 0420

 c   610 324 5500

 f    215 243 7699



  <mailto:isaligman(at)Saligman.com> isaligman(at)Saligman.com

 ________________________________  Message 2  _____________________________________

 Time: 06:52:44 AM PST US

 From: "Jan Mevis" <jan.mevis(at)informavia.be>

 Subject: RE: Spades



 If you mean the original Russian spades on the outer end of the ailerons,

 yes. The difference when doing aerobatics is quite apparent. Although I

 still need both hands for rolling. It won' make you roll faster, of course,

 only easier....

 But most of my collegue Yakista's consider it a very ugly modification.

 Jan Mevis



 Yak 50 RA2005K

 From: owner-yak-list-server(at)matronics.com

 [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of Ira Saligman

 Sent: dinsdag 12 februari 2008 15:07

 Subject: Spades

 Is anyone familiar with putting spades on a Yak 50?

 Ira Saligman



 o   610 940 0420



 c   610 324 5500



 f    215 243 7699

  <mailto:isaligman(at)Saligman.com> isaligman(at)Saligman.com

 ________________________________  Message 3  _____________________________________

 Time: 08:30:36 AM PST US

 From: "Roger Kemp M.D." <viperdoc(at)mindspring.com>

 Subject: RE: Spades



 Ira,



 If I am not mistaken, does the 85 50 that you have not have Shovels on the

 wing tips?



 If so, why change to spads?



 I'm flying my 78 without either quit comfortablely.



 Doc

 From: owner-yak-list-server(at)matronics.com

 [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of Ira Saligman

 Sent: Tuesday, February 12, 2008 8:07 AM

 Subject: Spades

 Is anyone familiar with putting spades on a Yak 50?

 Ira Saligman



 o   610 940 0420



 c   610 324 5500



 f    215 243 7699

  <mailto:isaligman(at)Saligman.com> isaligman(at)Saligman.com

 ________________________________  Message 4  _____________________________________

 Time: 09:00:00 AM PST US

 From: "Richard Goode" <richard.goode(at)russianaeros.com>

 Subject: Re: Spades



 MessageThe Yak 50 "spades" are the devices on the wing tips,which came out

 in 83.

 Not very attractive but do lighten the aileron loads.

 Richard Goode

  ---

pa3arw(at)euronet.nl
Guest

Posted: Tue Jun 03, 2008 4:21 am Post subject: Yak-List Digest: 13 Msgs - 02/12/08

Does anybody know the equivalent oil designation for W100 at Esso (Exxon??)



Hans O.

Dutch Yak Driver

dsavarese0812(at)bellsout
Guest

Posted: Tue Jun 03, 2008 4:50 am Post subject: Yak-List Digest: 13 Msgs - 02/12/08

Jacques,

In my opinion it would be somewhat impossible to seal the aileron gaps on a

52 or 50 because the pivot point of the aileron is aft of the leading edge.

The aileron protrudes below the wing gap when the aileron trailing edge is

up.  The reason for the design is to keep the ailerons functional during a

full stall, which has been proven in spin testing to be valuable in spin

recovery by using in-spin aileron.

Dennis



---

jan.mevis(at)informavia.b
Guest

Posted: Tue Jun 03, 2008 4:57 am Post subject: Yak-List Digest: 13 Msgs - 02/12/08

I just wonder if this gap sealing will make a big difference. Perhaps a few

degrees per second ? Is there any scientific data about this ?



Jan



--

buddairbum(at)cox.net
Guest

Posted: Tue Jun 03, 2008 6:13 am Post subject: Yak-List Digest: 13 Msgs - 02/12/08

Having gap sealed a number of Pitts, I can categorically state that it makes

a significant different. Spades lighten the forces, but gap sealing really

effects the roll rate. I've also flown at least one Mustang in which the

"curtains" a canvas gap seal that attaches to the front of the ailerons was

totally deteriorated and that airplane was almost a two-handed machine with

any speed at all on it (which they all are, but this one was worse).



bd

On 6/3/08 5:54 AM, "Jan Mevis" <jan.mevis(at)informavia.be> wrote:



[quote] 

 

 I just wonder if this gap sealing will make a big difference. Perhaps a few

 degrees per second ? Is there any scientific data about this ?

 

 Jan

 

 --

viperdoc(at)mindspring.co
Guest

Posted: Tue Jun 03, 2008 7:46 am Post subject: Yak-List Digest: 13 Msgs - 02/12/08

Jacques,

Since you are in Belgium, I suggest you have a direct conversation with Vytas at Termikus. Take a close look at your aelirons and those of a Pits. The YAK's ailerons are designed to give an effective aileron at low air speeds as well as being effective in a spin (a stalled wing). They act much like a fowler flap. A gap seal will completely take away the advantage of an effective aileron at speeds as low as 57 mph.

At least that is my humble opinion. Along with Vytas's too.

Roger Kemp 



--

buddairbum(at)cox.net
Guest

Posted: Tue Jun 03, 2008 8:09 am Post subject: Yak-List Digest: 13 Msgs - 02/12/08

I haven't looked at a Yak's ailerons. What makes them so different? Are they

Frieze  type or what?



Besides, temporarily gap sealing an aileron to see if it is effective is an

hour job. Use two pieces of wide packing tape face to face, overlapping an

inche or so. Snake it up through the gap and press it in place. Fly it, see

what the difference is and, if you don't like it, remove it. If you like it,

go for something more permanent.



Speaking as an aeronautical engineer, there are only a few aileron designs

that don't benefit from eliminating pressure loss through the gap. Those are

generally identified as being separate airfoils that are largely

disassociated from the wing and their function is to produce lift on their

own, not change the camberline (see Junkers designs), which is the case with

all "normal" ailerons. I've flown and been around most Yak models and

nothing jumped out at me as being unusual about their ailerons, but then, I

wasn't looking for it either.



Someone enlighten me on this. I'm never too old to learn something.



bd

On 6/3/08 8:43 AM, "Roger Kemp" <viperdoc(at)mindspring.com> wrote:



[quote] 

 

 Jacques,

 Since you are in Belgium, I suggest you have a direct conversation with Vytas

 at Termikus. Take a close look at your aelirons and those of a Pits. The YAK's

 ailerons are designed to give an effective aileron at low air speeds as well

 as being effective in a spin (a stalled wing). They act much like a fowler

 flap. A gap seal will completely take away the advantage of an effective

 aileron at speeds as low as 57 mph.

 At least that is my humble opinion. Along with Vytas's too.

 Roger Kemp 

 

 

 

 --

jan.mevis(at)informavia.b
Guest

Posted: Tue Jun 03, 2008 11:05 am Post subject: Yak-List Digest: 13 Msgs - 02/12/08

I think indeed that the lip of the aileron protrudes somewhat in the

airstream.

But even if it is possible to gain a higher roll rate, I just wonder if it's

worth the effort. You can't turn a Yak 52 into a Sukhoi (and that goes for a

Yak 50 too).



Jan



--

buddairbum(at)cox.net
Guest

Posted: Tue Jun 03, 2008 11:20 am Post subject: Yak-List Digest: 13 Msgs - 02/12/08

You may be describing a Frieze aileron, which is what I assumed they have.

Maybe not. If so, it is designed so the nose of the up aileron sticks down

into the wind to generate more drag and limit adverse yaw. There is the

mistaken thought that air is meant to flow over the top of the aileron

through the gap as if it is a slotted surface similar to a Fowler flap. That

is not the case. The tighter the gap (or if it's sealed), the more effective

it will be. 



Does the nose stick down when the trailing edge is faired?



bd

On 6/3/08 12:02 PM, "Jan Mevis" <jan.mevis(at)informavia.be> wrote:



[quote] 

 

 I think indeed that the lip of the aileron protrudes somewhat in the

 airstream.

 But even if it is possible to gain a higher roll rate, I just wonder if it's

 worth the effort. You can't turn a Yak 52 into a Sukhoi (and that goes for a

 Yak 50 too).

 

 Jan

 

 --

dsavarese0812(at)bellsout
Guest

Posted: Tue Jun 03, 2008 11:56 am Post subject: Yak-List Digest: 13 Msgs - 02/12/08

Yes, the nose or leading edge of the aileron does stick down below the 

bottom surface of the wing.  At high angles of attack, the air does flow 

through the gap giving the aileron effectiveness.

Dennis



---

buddairbum(at)cox.net
Guest

Posted: Tue Jun 03, 2008 12:14 pm Post subject: Yak-List Digest: 13 Msgs - 02/12/08

If that's the case, then, you're right, sealing them would be counter

productive. That kind of aileron design is seen very seldom because it's

only advantage is at high AOA (and may not actually work that well there)

and it is a very high drag design. On the other hand, the -52 didn't have

"low-drag" anywhere in its design criteria, did it?



As I'm thinking about this, I still think someone should try gap sealing

because there's a high possibility we're reading this wrong: an aileron set

up like this, although high drag, would really control adverse yaw well

because the parasite drag would change the instant the aileron is even

slightly deflected. As the nose continues down on the inboard aileron, its

drag skyrockets, while the drag on the outboard aileron drops noticeably

because the nose is retracted into the wing. Although high drag in level

flight, this would be a clever way to minimize adverse yaw and keep from

using differential ailerons for the same purpose. Any flow through the gap

would disrupt airflow and slow the roll rate, not increase it.



If I owned a -52, I'd have gap seals on it this afternoon to find out.



bd

On 6/3/08 12:53 PM, "A. Dennis Savarese" <dsavarese0812(at)bellsouth.net>

wrote:



[quote] 

 <dsavarese0812(at)bellsouth.net>

 

 Yes, the nose or leading edge of the aileron does stick down below the

 bottom surface of the wing.  At high angles of attack, the air does flow

 through the gap giving the aileron effectiveness.

 Dennis

 

 ---

dsavarese0812(at)bellsout
Guest

Posted: Tue Jun 03, 2008 12:27 pm Post subject: Yak-List Digest: 13 Msgs - 02/12/08

Nope!  Sure didn't ("low-drag" anywhere in its design criteria")



---

wlannon(at)persona.ca
Guest

Posted: Tue Jun 03, 2008 4:39 pm Post subject: Yak-List Digest: 13 Msgs - 02/12/08

I will climb out on my usual limb here and suggest that the Yak 52 aileron 

is the same as the CJ though the truth is I don't know.



The CJ aileron is a very standard Frieze balanced, differential throw system 

that works to minimize adverse yaw exactly as Budd has described. The gap in 

the Frieze design is kept to the minimum practical for safe clearance. The 

system is exactly the same as the Harvard/T6 and many other aircraft.  Gap 

sealing would be somewhat difficult, maybe not a good idea and, I think, 

would be of little value.



Walt



---

buddairbum(at)cox.net
Guest

Posted: Tue Jun 03, 2008 5:47 pm Post subject: Yak-List Digest: 13 Msgs - 02/12/08

Until the S-1T and late S-2A Pitts, they all had Frieze ailerons and we

routinely gap sealed them. Boosted the roll rate a solid 25% (that's a

guess) or more. And it's not as hard as it appears.



However, if as someone said, when the trailing edge of Yak aileron is faired

with the flaps and the tips, the nose is protruding below the wing, we don't

have a Frieze aileron. We have some sort of hybrid.



bd

On 6/3/08 5:36 PM, "Walter Lannon" <wlannon(at)persona.ca> wrote:



[quote] 

 

 I will climb out on my usual limb here and suggest that the Yak 52 aileron

 is the same as the CJ though the truth is I don't know.

 

 The CJ aileron is a very standard Frieze balanced, differential throw system

 that works to minimize adverse yaw exactly as Budd has described. The gap in

 the Frieze design is kept to the minimum practical for safe clearance. The

 system is exactly the same as the Harvard/T6 and many other aircraft.  Gap

 sealing would be somewhat difficult, maybe not a good idea and, I think,

 would be of little value.

 

 Walt

 

 ---

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