To slat, or not to slat?

[Guest Redair]

That is the question... So opinions please on whether the Savannah should be built with or without slats. It was on the original design for the aircraft, so is the VG wing just an alternative or a real improvement on the slat type wing?

 

I would like to have a better idea on this before I commit to ordering a Savannah, as I don't really want to build and then have to alter the wings later.

 

Regards Redair.

 

 

[Yenn]

A friend of mine built a Savannah and didn't fit the slats originally. He later fitted V.Gs and it performs very well. believe he did fit the slats just prior to fitting the VGs, to get performance figures. I will ask if he has the numbers when I next see him, or he may even be reading these posts and wish to post them himself.

 

 

[cherk]

http://stolspeed.com check out John Gilpins work on VG's . The Savannah VG wing has a more conventianal extended leading edge, retaining MAC ...............reduced drag and fuel effiency being big positives .........

 

Just my view.......may be worth what you pay for!

 

 

[Guest landmann]

Time will tell if the complexities of the advanced wing pay off . Mine has 212 hours so far. I have never flown a standard wing or one with vg's.

 

Here are a few things abourt the adv wing. One person, full fuel, 100 hp rotax.

 

1) Steady, trimmed, climb, 5000 rpm, from sea level at 1000 ft per minuite. At 10,0000 still climbing at 650 ft per minute. At 14,000 ft still climbing at 350 ft per minute at 16,400 ft the wing stalled.

 

2) crusing at 5000 rpm with Kiev prop, for three hours, multiple tests, average 95 statute miles per hour and 5.25 gal of mid range (89 oct) mogas per hour.

 

3) Can "kite" with full flaps in 35mph winds, zero ground speed as per gps, with no undue yaw surprises in gusts.

 

4) Lands with half flap in 15 knot (tower report) direct cross wind. Power as necessary to maintain direction and altitude. Very stable and easy to taxi.

 

5) Holds altitude and direction very well at high speed low passes over a two mile runway (5-10 ft) with or without wind up to 100 mph or put the flaps down and mush along. I have the dynon efis so can not get an airspeed reading, gps reads 40mph ground speed and the angle of attack is about 8 degrees. There is still room for more nose up and more power to go slower but I will leave that one for Eric at Skykits.

 

6) I have tried my best to give the facts without too much bragging but it looks like I just can't help myself. The Savannah ADV is soooo much fun to fly. 800 ft agl.. down wind 95 mph...abeam the numbers..carb heat on.. Throttle back.... nose down 10 degrees...bank 35 degrees...1200 ftm decent.. power up to round out 100 ft agl, 200 ft from numbers dead on center line..nose up... flaps down..power as necessary... land and taxi to parking in less than 500 feet.

 

One other thing I would hiiiiiiighly reccomend is that you go with the single y stick.

 

Martin

 

4)

 

 

[Guest Redair]

Thank you each, this is what I love about this website... all the help and advice. I figure that by the time I'm finished asking all my dumb questions, I'll have all I need to make all the right choices right at the start.

 

Thanks again, Redair.

 

 

[markendee]

Best check with a dealer but I was under the impression slats were now unavailable.

 

Stand to be corrected.

 

 

[Guest Redair]

Ah, that may well be so. I was only going on what I had previously heard, and had been under the impression that you could order them if you really wanted to have them. All academic now though, as I think the VG wings sounds like the way to go.

 

Redair.

 

 

[Guest J430]

Have flown both

 

I think about 10-15 knots faster in the new VG wing from memory and the stall etc is about the same.

 

I would definately go the VG's and dont forget the brace upgrade if you have not done it.

 

They are still a bloody slow machine, but a heck of a lot of fun!

 

J:thumb_up:

 

 

[Flyingphot]

I have owned a savannah with slats and flew 157 hrs. Sold it as I got an offer I could not refuse. Then built VG savannah and have now flown 170 hrs.

 

Differences - about 1 knot higher stall (23Kn as opposed to 22Kn with slats) - 9 Knots extra cruise (88Kn as opposed to 79Kn with slats @ 5100rpm) - this gives a fuel saving of about 12%.

 

The flying characteristics are much the same but on short field landing the slatted version tended to drop out rather suddenly during hold off, whereas the VG version tends to float just a little. This seems to make the landings just that little bit smoother. I fly from a 3 acre property on which I have a 140M (450foot) main strip and 80M (250 foot) cross strip so all my landings are short field. I use the main strip up to about 15-20 Knots cross wind. More than this and I use the cross strip.

 

My advice - go for the VGs every time.

 

Happy Flying

 

Bill

 

 

[Guest Redair]

Flyingphot, is that with a 100hp or 80hp engine?

 

Redair.

 

 

[Guest J430]

flyingphot

 

I think we both know you get more than that in the cruise......and its a lot quicker than the slatted one. Are you sure you have your glasses on:laugh:

 

I think I have a nice pic of a Savannah somewhere......

 

 

And how about a nice close look at those VG's.......

 

 

Cheers!

 

J:wave:

 

 

[Flyingphot]

Nice pics dave

 

I know my speeds are right but I'm not so sure about the taco. At 5100rpm indicated Ionly burn about 15 lt/hr which I think should be higher. Maybe my 5100 is really less. Don't care though as I fly a great machine.:big_grin::big_grin::big_grin: (can't seem to get the grin off)

 

 

[markendee]

VG=Very Good

 

 

[vk3auu]

Flyingphot "At 5100rpm indicated I only burn about 15 lt/hr which I think should be higher"

 

Looks a bit like your prop pitch is a bit fine.

 

David

 

 

[vk3auu]

This might be slightly off topic, but is a good demo of vortex generators. I'm perplexed as to why Rod Stiff says they don't work on a Jab 160.

 

http://www.stolspeed.com/601-hds-video/

 

David

 

 

[Guest Redair]

David, not off topic at all.... they really do seem to make a marked difference to the performance of the wing. Looks like VGs are the way to go.

 

Redair.

 

 

[BigPete]

I saw some VG's on a Jabiru at Narromine - never got to find out from the owner about them though.

 

rgards

 

 

[Guest landmann]

Please click one of the Quick Reply icons in the posts above to activate Quick Reply.

 

 

[vk3auu]

I notice that Van has an RV12 in the works for the LSA category. He tried VG's to try and get the stall speed down, apparently because the initial wing was a bit short, and he reckons they didn't work.

 

Looks like it will be a nice aircraft when he gets it sorted out.

 

David

 

 

[Flyingphot]

As ar as I can work out VGs are not supposed to change the stall speed. (this can be demonstrated by flying a Savannah without them as a mate of mine did for some time). What they do is clean up the stall characteristics. Without them the stall can be vicious with severe wing drop. With the VGs she becomes the pussycat we all love.

 

Bill

 

 

[flymate]

hello

 

have a question regarding Savannah slats length.  I bouth a Savannah with slats removed ( VGs installed) and want to ferry the plane . Slats will go by road.. so,, ....: are the Savannah slats in 2 pieces ( like the 701 ) or just one pièce ( that won't fit a car )

 

if they do separate...is it just few rivets to remove at the junction   ow more work..

 

thanks

 

Jacques 

 

the plane  

 

 

 

 

 

 

[IBob]

Flymate, if nobody else responds, you could message JG3 here with your question here. Or visit his website:

 

https://stolspeed.com/

 

 

[flymate]

Thanks

 

I did checked in the web site..which I read so many times. specially lately as we installed the VGs on a HDS 601

 

HUGE difference    THANKS JOHN

 

will try to contact him through this forum..

 

you're in Wairarapa..!!  I will be there in December , scooting down to Rangiora for couple months.

 

cheers