making landings easier

[Roger Lee]

VG's

[Jim Meade]

The Carbon Cub SLSA says it comes with VG.

[FlyingMonkey]

The Carbon Cub SLSA says it comes with VG.

 

 

I think Roger just meant that we can't use them on a CT since they didn't come with them, without an MRA from FD that would either be denied outright or be prohibitively expensive due to their typical costs for "engineering studies".

[Roger Lee]

VG's on a CT so it will be less speedy before you touch the wheelies.

I think that's about got it.

[Jim Meade]

VG's on a CT so it will be less speedy before you touch the wheelies.

I think that's about got it.

Don't be so cryptic, Roger. Did you say above that CT could not use them or did you mean something else?

[Doug G.]

Don't you see Lee is funny with his VGs, CTs, and wheelies.

[Roger Lee]

Tough crowd here at MGM tonight.  

Not cryptic, just being funny.

CT's can not use VG's unless you are ELSA and then there is no real study of their use on a CT. I have no doubt they would help at slow speeds at landing.

[Anticept]

Tough crowd here at MGM tonight.  

Not cryptic, just being funny.

CT's can not use VG's unless you are ELSA and then there is no real study of their use on a CT. I have no doubt they would help at slow speeds at landing.

Actually, I am trying to get ahold of OSU aeronautical engineering. They have a wind tunnel. I am not sure how big, but i want to test VGs in it.

[WmInce]

Actually, I am trying to get ahold of OSU aeronautical engineering. They have a wind tunnel. I am not sure how big, but i want to test VGs in it.

 

Just a suggestion, but you may get some good information from Cub Crafters on VG's.

When I was considering the Sport Cub S2, I talked to them about that and they were very knowledgeable.

[Roger Lee]

I have experience with VG's, just not on a CT. Personally unless I had to always get into tight air strips Or had a significant reason for them I don't really care for them. Landing and stall speed is irrelevant and just goes with the individual plane.

[fevlok@mmhs.co.za]

This is about it : no experience on the ctsw with vg's only speculation  ,

 

Boy am i am going to get it because of  the following statements but here we go :

 

The vg's not only lower the stol speed but 3 byproduc's  is for me the benefit that i got with them

1 it also make the plaine more controlable at lower speeds  and  

2 when the  wing stol from the root propegating outwards it slow's this down and for me that help to take the sudden drop out of the plaine , and 3  to add more controversy  : the new "CTLS with it's longer tail land much easier,   why ?   (remember the Cesna Cardinal issue )  Vgs on the stabelater of the ctsw  make it  more afective in the high angle of attack? ,that is how it feel to me

 

 

In the end the VG's might just be a mental chrutch ?  Like when i start to mistrust my bow , get a new one and al of a sudden I shoot better ? all in the mind who know's  It worked for me making my landings better !!

 

The only selution is one of you guys must come and visit me on the dark continent . Winter is better flying time and also hunting ,

 

Kiewiet

[Rogerck]

Kiewiet,

 

Can you be more specific about how the VG's affected your landing envelope?  With VG's what is your over the fence speed and approximate touch down speed?  Do you just scale everything back from recommend CT landing speeds or land at recommended speeds but with a softer touchdown?   Also, what effect do the VG's have on high end air speed?  Finally, have you changed the placard speeds on the instrument panel?

 

I have an ELSA CT and have toyed with the idea of installing VG's.  Although my CT landings are good, I can not be consistent on slick downs.  When I flew an RV6, almost all landings were sd's and easy to make consistent.

 

Roger Kuhn

[fevlok@mmhs.co.za]

Dear Roger  Kuhn

 

The reason for the vg experiement was the claims on the website of  STOLSPEED vorteg generaters  ( i think it is a Australian based produc) I don't know how to add a link ,the above can be Google 

 

Our CTSW 2007 in calm conditions was always a chalance to land softly, now and again it catch me out with a feelable thumb , because of a sudden ,with out warning, sink  proberbly not bad if you except that tipe of landing , but far inferior to the rv 9 or my Mooney or the MCR4S (Dynero)

 

I did not change my normal landing at al after the vg's  But my landings is much more  consistant good , infact power of and  all flap settings have not experience a drop again ,  and can counter her 'docile' sink rate by stick only right onto the runway , were before a sudden drop was counter by a short burst of power  or that help was to open the throtle to about 200 refs above idle

 

Here is my normal  landing : Short final on 15 flaps 60knots ( 30\40 flaps 55knots ) ,right into the last part of the flair , paralell with the runway at about 55 knots(30/40 flaps 50knots ) i transfer my attentions to the outside ,hold her of till the nose is up "landing position " and then let her slowly setle

 

With the vg's i have't change a thing axcept that i don't need power or a sudden burst of power , playing with power one can ride her on the back wheels as long as one want to now

 

Hope it help

 

My biggest problew was to decide were to put them on the wing and stabilator

 

I normaly fly to a farmstrip 270 knot. miles from home and top end have not notice any drop in cruise speed

 

Hope it help

 

Kiewiet

[Rogerck]

Kiewiet,

 

With the VG's installed, what are your power off and on stall speeds at different flap configurations?   Also, how did you determine how far back to place the VG's?  

 

Thanks

 

Roger Kuhn

[Anticept]

You can tape strings on the wing and mount a camera to see where the turbulence develops when you stall. VGs need to be placed a little bit forward of the stall line (generally it is right around the highest camber point).

[Roger Lee]

usually VG's are approximately 12" from the leading edge on with an aircraft with a wing cord length like ours.

[Jim Meade]

You can tape strings on the wing and mount a camera to see where the turbulence develops when you stall. VGs need to be placed a little bit forward of the stall line (generally it is right around the highest camber point).

Where do you mount the camera on a CT to see the top of the wings and the bottom of the stabilator? What mounting equipment is used? How high above the wing do you need the camera to be to get a good view?

[Anticept]

You just need to see where that boundary layer separation line is, so it doesn't need to be very high above the wing. It's blatantly obvious once the air becomes disrupted.

 

Like this (soft stall at 3:50ish):

 

[Jim Meade]

You taught me to suck eggs but you didn't answer my question. I'd appreciate suggestions from anyone on my question in #97.

[fevlok@mmhs.co.za]

Dear Roger

 

Yes the precise placing was a problem

 

I tried to get the wing dimentions from ctsw Germany to do a wind tunnel test at the university but it was impossable ,to mesure it at the service centre  would take to long so this is what i did :

 

 If you go into the stolspeed web site they say  between 7- 11% behind the leading edge rather err to the front than to far back  To far back and it doesnt work to far forward can theoretical increase drag, ( it is not to place sensitive ) 

 

Here is what i have done:

 

1 The attitude of the plaine  level  (nose to tail axis/use a spirit level on the centre console between the seats  )

 

2 use a plump line  to touch the front of the wing and in the midle of this  make a mark for the leading edge  (on a piece of masking tape stuck to the wing

 

3 do this on the inside and midle and outside of wing

 

4 Use  fish gut from inside to outside of the wing to mark the leading edge

 

5  i messure then a streight line from the edge of the flap o degrees  up to the plump line  on top

 

 take 7% of this distance  ( think it is close to 85mm , messurements stil in the plaine) and messure this from leading edge , now use fish gut for a paralel line to the leading edge .

 

6 The foot of the vg's now touch this line  stolspeed vg's have cut out markers were  vg's must be placed

I only placed vg's up to the ? stol strip edge

 

7 The stabilator  i also placed it in a horisontal position, get the leading edge,  messure now from the underside , my vg's foot plate is on 9%  but it is because of 3m tape i have put on the leading edge for stones on the farm strip ,realy work well )

 

Stolspeed

 

I didn't care for it much because i am to stuped to do it accuratly : My problem is full yoke back the plaine attitude is much nose higher than i am use to, that surely must reduce the accuricy of the indicated airspeed because of the pitot posision to airflow  and secondly  the plaine first start to loose hight  and then after a delay of 1-3 knots the nose "nod "

 

 I was more concern how the plaine will behave in stol  so I took a friend of mine that just made the national team for aerobatics  on the test flight to see how the plaine behave on power of and on stols in all flap config: docile as ever (ball centre)

 

So the stol speed is lower but as one put it to me how short /slow do you want to land ?

 

My reason for the vg's was to improve my landings and that it did ,  I also note a better response of aleron and stabilator at landing speed

 The improvement was  so much so that before i refuse that any one else do a conversion on the ct , now i am re thinking this postition so drastic is the diference in landing

 

My safety margins was always 1.3 x stol  on final and i still stick to it  so now even a bigger margin : great !

[Jerry]

I used to land with no power until reading this topic.  At no power it seemed to be a crap shoot as to what kind of landing I was going to have, about 50% good, 50% not so much.    Started adding a little power on base turn and cut power just before touch down, landings have improved dramatically.  Thanks for the tips, much appreciated!