Guest Teenie2 Posted August 2, 2007 Share Posted August 2, 2007 Has anyone fitted vortex generators (wing or and tail,fus), and if so what performance changes did you get? Link to comment Share on other sites More sharing options...
Yenn Posted August 2, 2007 Share Posted August 2, 2007 A friend fitted them to a Savannah and did comparison tests against the slats. He did not keep the slats on, said that the vortex generators were as good or maybe better. I will probably see him this weekend and see if he still has all the figures. If he has I will try to get them posted. Link to comment Share on other sites More sharing options...
vk3auu Posted August 2, 2007 Share Posted August 2, 2007 www.microaero.com/CS_PDF/Cessna/182-Swept-CS.pdf. put "Vortex Generators" into Google. The above probably says it all. I have removed the leading edge slats from my Zenair CH701 and replaced them with a row of VG's along the top of each wing. I have also put a row along the underside of the elevator. There doesn't appear to be any downside. There is less wing drop in the stalls and drag is reduced quite considerably. I now get 69 knots cruise at about 15 litres per hour and 4600 rpm as previously I got 65 knots cruise at 5100 rpm and just under 17 litres per hour. In a more conventional aircraft you will probably find a slight reduction in top speed, as the VG's will introduce a tad more drag, but at the other end you will find that the approach speed will be around 10 knots slower and it will feel much more stable. There are STP's for most GA aircraft. Some also fit them to both sides of the rudder. I would suggest that the Jabirus would find enormous benefits from them, particularly in the landing speed department. Link to comment Share on other sites More sharing options...
vk3auu Posted August 2, 2007 Share Posted August 2, 2007 http://www.landshorter.com/page3.html There, I have done it for you. David Link to comment Share on other sites More sharing options...
TechMan Posted August 3, 2007 Share Posted August 3, 2007 A friend fitted them to a Savannah and did comparison tests against the slats. He did not keep the slats on, said that the vortex generators were as good or maybe better. I will probably see him this weekend and see if he still has all the figures. If he has I will try to get them posted. I hope he has put the different leading edge on too. Simply removing the slat on the original wing is not something that is endorsed by the factory and is certainly not recommended. It has implications on the CG range and the distribution of lift as you are removing a chunk of the wing chord. Then again, it is 'experimental' ... Chris Link to comment Share on other sites More sharing options...
vk3auu Posted August 3, 2007 Share Posted August 3, 2007 According to discussions I had at Narromine, the new leading edge on the Savannah does not work as well as it might and the stall characteristics are not as good as if you retained the original wing with the slats removed. On the Zenair CH701, the CoG range seems to be about the same as it was with the slats. John Gilpin might be the man to give more information on this. David Link to comment Share on other sites More sharing options...
bushpilot Posted August 3, 2007 Share Posted August 3, 2007 http://www.landshorter.com/page3.htmlThere, I have done it for you. David The movie clips of those river (more creeks by our measurement...) landings is incredible! Those guys sure know wot STOL is all about! ;) Link to comment Share on other sites More sharing options...
Yenn Posted August 5, 2007 Share Posted August 5, 2007 Tech man. I saw the friend with the Savannah and he advised that the VG's were far superior to the slats, with no downside. I was not aware of any need to change the leading edge and I do not know if he did that. I only had time for a short conversation with him but will catch up again later. Unfortunately he is a coalfields shift worker, so comes and goes at odd times. Link to comment Share on other sites More sharing options...
eightyknots Posted April 15, 2014 Share Posted April 15, 2014 Has anyone had any success fitting VGs to 'rag' aircraft? (I am thinking that a Skyranger or Hanuman could have better performance with them?) The real question is, can they be successfully fitted to the wing surface? Link to comment Share on other sites More sharing options...
Old Koreelah Posted April 15, 2014 Share Posted April 15, 2014 ... can they be successfully fitted to the wing surface? Yep. They stick to painted fabric. Link to comment Share on other sites More sharing options...
rankamateur Posted April 15, 2014 Share Posted April 15, 2014 the stall characteristics are not as good as if you retained the original wing with the slats removed. In the seven years since this was posted at least half a dozen Savannah with slats removed and wing profile unmodified, have been bent, at or near MTOW flying at low speed when they decide to bite their unsuspecting owners! Not only does the then new VG wing have reliable stall characteristics, it has also been carried forward to the XL and S models unchanged except for thr recent 600Kg upgrade. I am wondering how much David's discussion partner at Narromine knew about the VG wing then and wether he has learnt anything to change his opinion since. Link to comment Share on other sites More sharing options...
kgwilson Posted April 15, 2014 Share Posted April 15, 2014 A friend who built a Savannah, when I asked him if the VGs worked, said the aircraft is actually dangerous without them. He never bent his Savannah & was often loaded up & from comments above he was right. Link to comment Share on other sites More sharing options...
rankamateur Posted April 16, 2014 Share Posted April 16, 2014 A friend who built a Savannah, when I asked him if the VGs worked, said the aircraft is actually dangerous without them. He never bent his Savannah & was often loaded up & from comments above he was right. Did he remove slats or have the extended VG wing profile? The VG profile is very similar to the old profile including the slat. Removing the slats, which form part of the aerofoil profile, changes the aerofoil significantly and moves you into test pilot territory. Problem is too many of these test pilots fly close to the ground, quite slow, loaded up and without parachutes so we really are lucky most of them are still with us, just with bent pride(and joy). Link to comment Share on other sites More sharing options...
eightyknots Posted April 16, 2014 Share Posted April 16, 2014 In the seven years since this was posted at least half a dozen Savannah with slats removed and wing profile unmodified, have been bent, at or near MTOW flying at low speed when they decide to bite their unsuspecting owners! Not only does the then new VG wing have reliable stall characteristics, it has also been carried forward to the XL and S models unchanged except for thr recent 600Kg upgrade. JG3 on this forum has done a lot of testing between the original wings with slats removed and VGs added versus the ICP VG wing. It is on his website and it appears to show that there is little difference in flight characteristics with the exception that the original wings with slats removed and VGs added gives a lower stall speed. Go to http://www.stolspeed.com/flight-testing-slats-vs-vgs and scroll about 1/3 of the way down for this comparison. Link to comment Share on other sites More sharing options...
rankamateur Posted April 16, 2014 Share Posted April 16, 2014 JG3 on this forum has done a lot of testing between the original wings with slats removed and VGs added versus the ICP VG wing. It is on his website and it appears to show that there is little difference in flight characteristics with the exception that the original wings with slats removed and VGs added gives a lower stall speed. Go to http://www.stolspeed.com/flight-testing-slats-vs-vgs and scroll about 1/3 of the way down for this comparison. Hank I have read Johns material previously thanks. John is a very capable pilot, not all the test pilots out there share his level of capability. Link to comment Share on other sites More sharing options...
eightyknots Posted April 16, 2014 Share Posted April 16, 2014 Hank I have read Johns material previously thanks. John is a very capable pilot, not all the test pilots out there share his level of capability. There is no doubt that John is a capable pilot. I have been in his plane . That flight was what got me interested in Savannahs. Link to comment Share on other sites More sharing options...
kgwilson Posted April 16, 2014 Share Posted April 16, 2014 Did he remove slats or have the extended VG wing profile? The VG profile is very similar to the old profile including the slat. Removing the slats, which form part of the aerofoil profile, changes the aerofoil significantly and moves you into test pilot territory. Problem is too many of these test pilots fly close to the ground, quite slow, loaded up and without parachutes so we really are lucky most of them are still with us, just with bent pride(and joy). I'm pretty sure he had the extended VG profile. Link to comment Share on other sites More sharing options...
rankamateur Posted April 16, 2014 Share Posted April 16, 2014 I'm pretty sure he had the extended VG profile. The holes are already in the sheet. Why wouldn't you install the VG's, it takes half an hour and they are part of the design. Link to comment Share on other sites More sharing options...
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