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#21
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Thanks for your reply, Paul.
Some comments below in context... "Paul Saccani" wrote in message ... On Sat, 24 Sep 2011 11:27:57 +1000, "Jeff R." wrote: I'm inclined to trust Chris Heintz, as the engineer/innovator, but at the same time he has (had - he's retired) a significant financial attachment to L.E. slats. Not just on the 701, but right up to th 850. Depends on your mission. The STOL performance of the 701 is such that most don't even need to use the flaps. The slats do dramatically steepen approach and departure, and if that's what you need.... Not so much need as "want". Catch is, I also "want" a decent glide slope and fuel economy. (yes, I know) I would note that unlike what CH states, the slatted wing does not act as though the chord is from the TE to the front of the slat, but rather, from the TE to the front of the wing. Which, if you look at the allowable %MAC for weight and balance, which uses the CH interpretation, those percentages are a little unusual compared with "regular" aeroplanes. Remeasure, using the front of the wing instead of the slat, and the %MAC values fall straight into the usual range. Thanks for that. I'd suspected as such, based partly on how well the de-slatted 701s seemed to perform. On balance, I'm inclined to favour VGs (Piper Cub didn't need slats), but I'm put off Savannah just simply because of their unethical poaching of CH's designs. They didn't poach a CH design. They made a slavish copy of a legitimate 701 cousin design by Max Tudesco, who has had a long involvement with CH's companies, and was involved in the design of the 701. He didn't like some aspects of the design and went his own way, whilst also making licensed quick build kits of the 701. The scummy Italian company was buying quick build kits from his company, and simply measured one for CNC copies to be made. They are actually more unethical than your first thoughts. Hehe International intrigue'n'all. I plan to cut the first stringers in about a year from now. As I recall, the stringers are all in the forward cabin, and all need solid rivets. You may find it worthwhile to buy those and the main spars from Zenith, with the solid riveting done. If you intend to build as per the edition 5, 7th revision, you will find that some items, such as the spar caps, are non-standard custom extrusions for Zenith. They will sell you a spar complete, but not the components to make the main spar. Still not decided on full kit or build from plans. I rather fancy myself at metalwork, but the cost of the raw materials makes the CNC cut kit awfully attractive. Now, if the US dollar would just oblige my falling down again... Personally, I'm happier using the slightly thicker alternative... Maybe I could build retractable slats? (joke) Well, it has been done, but the company was bought out, I'm not sure if they are in production again. PegaSTOL was the old company. Yup. Saw that, and like the idea (lots) but the weight? Most people don't know this, but at one time (late eighties), CH was recommending that some CH701 use VGs attached to the slat! ! Seems a bit greedy. I take it that didn't work... (?) What you lose if you use VG instead of slats, besides the steepness of approach and departure, is the "stall" controllability. With the slatted 701, you can go way on the wrong side of the lift/drag curve, so you no longer have enough lift to stay up, but aileron remains effective and there is no wing drop. It just gets "mushy". Sans slats, with VG, you get a conventional stall, and wing drop. Nothing nasty, but a little faster, with a little less control. Yes, and this is the main reason I'd like to retain the slats. Now, the slats are great, but there is an awful lot of drag, and you end up with an engine out glide ratio about the same as a helicopter, 4:1. It'll cost you fuel to haul their weight around, and fuel to counter their drag. IIRC, they weigh around 12 kg. 12kg. Hnh. I have main courses at dinner bigger than that. (anecdote edited for the sake of propriety) Still, the drag is a real bummer. I still don't know how much long distance stuff I'll be doing - I hope a lot - but then I suspect that good STOL will also be a significant factor in my dream "trip-around-Australia". Endurance - economy - STOL? Helluva balancing act. Having said that, I'm leaving mine on for the moment. With an EA81 and a 68" 3 blade warp drive at 16.5°, mine does 70 kts @ 13 litres an hour, @4,000 RPM for the engine, 1,820 RPM for the prop. Hmmm. None too shabby. 75hp? That enough for good STOL two-up? How's the rate of climb? In due course, I plan to fair my struts, but you could order the strut material for the 750, which is in an aerofoil shape, and save yourself a lot of bother. Fair them rather than remove them? Do you need the extra square feet, considering what you said above about the slat's contribution to total chord? VG for the elevator is a very good idea - you can get those from Zenair. I'm thinking of removing the slats and the entire mixer system and control for the flaps. If you look at the skyfox versus the kitfox, they removed the mixer system entirely - at CASAs request - and performance was still satisfactory. If you look at the 750 mixer, you will see that it is a much more elegant design. As I say, I am contemplating deleting the 701 mixer, but if I decide that flap is still necessary, I will install a 750 style mixer, which is far more elegant and lighter too. Also, having the elevator bell crank bracket on the aileron torque tube sucks. I have a part 35 engineered solution, where the bracket is mounted on a fitting that is fixed to the airframe, and allows the torque tube to rotate inside it. This gets rid of the elevator cable tension issue, where the aileron and elevator interfere with each other. Thanks again for all that Paul. It's good to toss this stuff around. (just had a quick look at your page at Zenith...) -- Jeff R. -- Cheers, Paul Saccani Perth, Western Australia. |
#22
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Back when I was MUCH younger I flew A3-B Skywarriors.
(http://www.soaridaho.com/Naval_Pictu..._12-Aug-64.jpg) It had aerodynamically actuated slats. They slid in and out using rollers on a track. When sitting on the deck gravity would cause them to extend. At normal cruising flight speeds the air resistance would push them in. They popped out at high angles of attack. The system worked pretty well; however, heaven forbid that one of them got stuck in while the other extended! Wayne http://tinyurl.com/N990-6F "Paul Saccani" wrote in message ... On Sat, 24 Sep 2011 16:32:53 +1000, "Jeff R." wrote: Thanks for your reply, Paul. Some comments below in context... "Paul Saccani" wrote in message .. . On Sat, 24 Sep 2011 11:27:57 +1000, "Jeff R." wrote: I'm inclined to trust Chris Heintz, as the engineer/innovator, but at the same time he has (had - he's retired) a significant financial attachment to L.E. slats. Not just on the 701, but right up to th 850. Depends on your mission. The STOL performance of the 701 is such that most don't even need to use the flaps. The slats do dramatically steepen approach and departure, and if that's what you need.... Not so much need as "want". Catch is, I also "want" a decent glide slope and fuel economy. (yes, I know) Indeed. VG are a good compromise. I plan to cut the first stringers in about a year from now. As I recall, the stringers are all in the forward cabin, and all need solid rivets. You may find it worthwhile to buy those and the main spars from Zenith, with the solid riveting done. If you intend to build as per the edition 5, 7th revision, you will find that some items, such as the spar caps, are non-standard custom extrusions for Zenith. They will sell you a spar complete, but not the components to make the main spar. Still not decided on full kit or build from plans. I rather fancy myself at metalwork, but the cost of the raw materials makes the CNC cut kit awfully attractive. IIRC, it was about four grand for all the aluminium sheet in my one. But I suspect that ordinary prices would be a good deal higher. Now, if the US dollar would just oblige my falling down again... Better take a good look at shipping costs and duties. Well, it has been done, but the company was bought out, I'm not sure if they are in production again. PegaSTOL was the old company. Yup. Saw that, and like the idea (lots) but the weight? No idea. I don't know how their mechanism works. I've thought it might be worth trying Tiger Moth slot style spring loading and cable locking. They get pushed back at speed, but pop out as you slow down. Locking is done to prevent accidental asymmetric extension - it aggravates any tendency to a spin. Most people don't know this, but at one time (late eighties), CH was recommending that some CH701 use VGs attached to the slat! ! Seems a bit greedy. I take it that didn't work... (?) It did, but it was only for some, which had a high drag at cruise speeds. The VG was a quick fix, but the location of the slat was changed as a general fix. It's just an interesting piece of trivia. What you lose if you use VG instead of slats, besides the steepness of approach and departure, is the "stall" controllability. With the slatted 701, you can go way on the wrong side of the lift/drag curve, so you no longer have enough lift to stay up, but aileron remains effective and there is no wing drop. It just gets "mushy". Sans slats, with VG, you get a conventional stall, and wing drop. Nothing nasty, but a little faster, with a little less control. Yes, and this is the main reason I'd like to retain the slats. Well, it is experimental, after all.... I'd stick with the slats first off, though you might want to consider redesigning the slat brackets so that they can be removed and re-instated, rather than using the wing without slats but still with the brackets, as per CH advice. I don't know if the brackets create a great mischief or not, but going with his recommendation seems a safe bet. Myself, I plan on keeping them and tuft testing to see how much of a mischief they make. I might use them for fences, that way, if the mission needs it, I can put the slats back on. 12kg. Hnh. I have main courses at dinner bigger than that. (anecdote edited for the sake of propriety) Baggage compartment is limited to 18 kg, it's a fairly significant weight for a little aeroplane. Still, the drag is a real bummer. I still don't know how much long distance stuff I'll be doing - I hope a lot - but then I suspect that good STOL will also be a significant factor in my dream "trip-around-Australia". It's a big country - plenty of space to land. Endurance - economy - STOL? Helluva balancing act. Having said that, I'm leaving mine on for the moment. With an EA81 and a 68" 3 blade warp drive at 16.5°, mine does 70 kts @ 13 litres an hour, @4,000 RPM for the engine, 1,820 RPM for the prop. Hmmm. None too shabby. 75hp? 100 HP. That enough for good STOL two-up? How's the rate of climb? I can't answer either of those yet. 600 fpm is the figure that comes to mind. In due course, I plan to fair my struts, but you could order the strut material for the 750, which is in an aerofoil shape, and save yourself a lot of bother. Fair them rather than remove them? Well, I do need them to keep the wings on.... Do you need the extra square feet, considering what you said above about the slat's contribution to total chord? Struts... The standard ones are round 4130 tube. The parasite drag of each sides struts is almost as much as the whole wing. The 750 uses aerofoil section aluminium extrusions. For the tube, you put thin fairings on them to reduce the drag. For the other idea, I reckon foam inserts could be shoved in the slots to reduce drag, either with or without VGs. Then you could remove them after long distance cruising to investigate off the beaten track. Less aggravation than taking the slats on and off, plus you could take the slats with you on a long trip. That would probably weigh less than a retractable slat and be less likely to create mischief. Also, having the elevator bell crank bracket on the aileron torque tube sucks. I have a part 35 engineered solution, where the bracket is mounted on a fitting that is fixed to the airframe, and allows the torque tube to rotate inside it. This gets rid of the elevator cable tension issue, where the aileron and elevator interfere with each other. Thanks again for all that Paul. It's good to toss this stuff around. (just had a quick look at your page at Zenith...) That saves me suggesting that you join Zenith Aero, though I don't recognise your name on the new members list. Those photos are pretty rough, I've taken some better ones, but haven't put them up yet. -- Cheers, Paul Saccani Perth, Western Australia. |
#23
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I think the A3 link is fixed and it should work .
Wayne wrote: Back when I was MUCH younger I flew A3-B Skywarriors. http://www.soaridaho.com/Naval_Pictu..._12-Aug-64.jpg It had aerodynamically actuated slats. They slid in and out using rollers on a track. When sitting on the deck gravity would cause them to extend. At normal cruising flight speeds the air resistance would push them in. They popped out at high angles of attack. The system worked pretty well; however, heaven forbid that one of them got stuck in while the other extended! Wayne http://tinyurl.com/N990-6F "Paul Saccani" wrote in message ... On Sat, 24 Sep 2011 16:32:53 +1000, "Jeff R." wrote: Thanks for your reply, Paul. Some comments below in context... "Paul Saccani" wrote in message .. . On Sat, 24 Sep 2011 11:27:57 +1000, "Jeff R." wrote: I'm inclined to trust Chris Heintz, as the engineer/innovator, but at the same time he has (had - he's retired) a significant financial attachment to L.E. slats. Not just on the 701, but right up to th 850. Depends on your mission. The STOL performance of the 701 is such that most don't even need to use the flaps. The slats do dramatically steepen approach and departure, and if that's what you need.... Not so much need as "want". Catch is, I also "want" a decent glide slope and fuel economy. (yes, I know) Indeed. VG are a good compromise. I plan to cut the first stringers in about a year from now. As I recall, the stringers are all in the forward cabin, and all need solid rivets. You may find it worthwhile to buy those and the main spars from Zenith, with the solid riveting done. If you intend to build as per the edition 5, 7th revision, you will find that some items, such as the spar caps, are non-standard custom extrusions for Zenith. They will sell you a spar complete, but not the components to make the main spar. Still not decided on full kit or build from plans. I rather fancy myself at metalwork, but the cost of the raw materials makes the CNC cut kit awfully attractive. IIRC, it was about four grand for all the aluminium sheet in my one. But I suspect that ordinary prices would be a good deal higher. Now, if the US dollar would just oblige my falling down again... Better take a good look at shipping costs and duties. Well, it has been done, but the company was bought out, I'm not sure if they are in production again. PegaSTOL was the old company. Yup. Saw that, and like the idea (lots) but the weight? No idea. I don't know how their mechanism works. I've thought it might be worth trying Tiger Moth slot style spring loading and cable locking. They get pushed back at speed, but pop out as you slow down. Locking is done to prevent accidental asymmetric extension - it aggravates any tendency to a spin. Most people don't know this, but at one time (late eighties), CH was recommending that some CH701 use VGs attached to the slat! ! Seems a bit greedy. I take it that didn't work... (?) It did, but it was only for some, which had a high drag at cruise speeds. The VG was a quick fix, but the location of the slat was changed as a general fix. It's just an interesting piece of trivia. What you lose if you use VG instead of slats, besides the steepness of approach and departure, is the "stall" controllability. With the slatted 701, you can go way on the wrong side of the lift/drag curve, so you no longer have enough lift to stay up, but aileron remains effective and there is no wing drop. It just gets "mushy". Sans slats, with VG, you get a conventional stall, and wing drop. Nothing nasty, but a little faster, with a little less control. Yes, and this is the main reason I'd like to retain the slats. Well, it is experimental, after all.... I'd stick with the slats first off, though you might want to consider redesigning the slat brackets so that they can be removed and re-instated, rather than using the wing without slats but still with the brackets, as per CH advice. I don't know if the brackets create a great mischief or not, but going with his recommendation seems a safe bet. Myself, I plan on keeping them and tuft testing to see how much of a mischief they make. I might use them for fences, that way, if the mission needs it, I can put the slats back on. 12kg. Hnh. I have main courses at dinner bigger than that. (anecdote edited for the sake of propriety) Baggage compartment is limited to 18 kg, it's a fairly significant weight for a little aeroplane. Still, the drag is a real bummer. I still don't know how much long distance stuff I'll be doing - I hope a lot - but then I suspect that good STOL will also be a significant factor in my dream "trip-around-Australia". It's a big country - plenty of space to land. Endurance - economy - STOL? Helluva balancing act. Having said that, I'm leaving mine on for the moment. With an EA81 and a 68" 3 blade warp drive at 16.5°, mine does 70 kts @ 13 litres an hour, @4,000 RPM for the engine, 1,820 RPM for the prop. Hmmm. None too shabby. 75hp? 100 HP. That enough for good STOL two-up? How's the rate of climb? I can't answer either of those yet. 600 fpm is the figure that comes to mind. In due course, I plan to fair my struts, but you could order the strut material for the 750, which is in an aerofoil shape, and save yourself a lot of bother. Fair them rather than remove them? Well, I do need them to keep the wings on.... Do you need the extra square feet, considering what you said above about the slat's contribution to total chord? Struts... The standard ones are round 4130 tube. The parasite drag of each sides struts is almost as much as the whole wing. The 750 uses aerofoil section aluminium extrusions. For the tube, you put thin fairings on them to reduce the drag. For the other idea, I reckon foam inserts could be shoved in the slots to reduce drag, either with or without VGs. Then you could remove them after long distance cruising to investigate off the beaten track. Less aggravation than taking the slats on and off, plus you could take the slats with you on a long trip. That would probably weigh less than a retractable slat and be less likely to create mischief. Also, having the elevator bell crank bracket on the aileron torque tube sucks. I have a part 35 engineered solution, where the bracket is mounted on a fitting that is fixed to the airframe, and allows the torque tube to rotate inside it. This gets rid of the elevator cable tension issue, where the aileron and elevator interfere with each other. Thanks again for all that Paul. It's good to toss this stuff around. (just had a quick look at your page at Zenith...) That saves me suggesting that you join Zenith Aero, though I don't recognise your name on the new members list. Those photos are pretty rough, I've taken some better ones, but haven't put them up yet. -- Cheers, Paul Saccani Perth, Western Australia. -- Android Usenet Reader http://android.newsgroupstats.hk |
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"Wayne Paul" wrote in message
... Back when I was MUCH younger I flew A3-B Skywarriors. http://www.soaridaho.com/Naval_Pictu..._12-Aug-64.jpg) snip Wayne http://tinyurl.com/N990-6F Wayne, You may be interested, Whidbey Island Naval Air Station recently obtained an A-3 and they're going to put it on a stick outside the main base with the two A-6s. Also the Seaplane Base has acquired a PBY and has it on display next to a PBY museum. It's worth seeing just to see the technology that was the state of the art in the 30's. Rich Isakson |
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"Jeff R." wrote:
but I'm put off Savannah just simply because of their unethical poaching of CH's designs. Just FYI: Eric Giles, the fellow who created Skykits Corporation (the U.S. agent or distribution company for the ICP Savannah) appears to be redirecting sales to another U.S. company he created called World Aircraft that will sell a Max Tedesco design. If you go to the Skykits website: http://www.skykits.com/ You can see where it redirects. A rather lengthy tale that claims to explain the origin of both the 701 and Savannah is posted here, and presumably why Giles shifted from ICP to Tedesco: http://www.stolspeed.com/origins-701-savannah |
#26
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Rich,
Thank you for the update. Several years ago during a VAH-10 reunion we tried to get the ball rolling for placing an A-3 on a stick. After that I got a bit out of touch with the progress. However, I sure hope that it is either a the bomber, or tanker version and NOT one of the *******ized EW contraptions covered with all kinds of antenna bubbles. (The EW things were based at Alameda, not Whidbey.) The PBY at the Seaplane Base will also be cool. In my early tours at Whidbey there were P5Ms at the seaplane base. If they had one of those on display, people would be surprised as to their size. (I was an navigation observer during a couple P5M squadron ORIs. It seemed like it took for ever for them to get airborne!) The designer of the glider that I fly was quite famous in the PBY community. http://www.soaridaho.com/Schreder/Sc...Biography.html Wayne Schreder HP-14 N990 http://tinyurl.com/N990-6F "Richard Isakson" wrote in message ... "Wayne Paul" wrote in message ... Back when I was MUCH younger I flew A3-B Skywarriors. http://www.soaridaho.com/Naval_Pictu..._12-Aug-64.jpg) snip Wayne http://tinyurl.com/N990-6F Wayne, You may be interested, Whidbey Island Naval Air Station recently obtained an A-3 and they're going to put it on a stick outside the main base with the two A-6s. Also the Seaplane Base has acquired a PBY and has it on display next to a PBY museum. It's worth seeing just to see the technology that was the state of the art in the 30's. Rich Isakson |
#27
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Yes, and this is the main reason I'd like to retain the slats.
How about using outboard wing only ailerons (might need to make them bigger) and keep the slats on the aileron portion, only? -- Jim in NC |
#29
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On 9-25-2011 04:40, Morgans wrote:
Yes, and this is the main reason I'd like to retain the slats. How about using outboard wing only ailerons (might need to make them bigger) and keep the slats on the aileron portion, only? -- Jim in NC Oh, like on the Globe Swift from the 1940s? Wonderful airplanes! Hard to find a good view of them, but this one shows it if you look closely... http://www.google.com/imgres?q=globe...429,r:3,s :73 And a bit better view... http://www.google.com/imgres?q=globe...tx=142&ty=9 1 And finally, from the top side... http://www.google.com/imgres?q=globe...82&tx=96&ty=37 Scott |
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How about using outboard wing only ailerons (might need to make them
bigger) and keep the slats on the aileron portion, only? -- Jim in NC Oh, like on the Globe Swift from the 1940s? Wonderful airplanes! A: Yep that was 'zacary what I had in mind! -- Jim in NC |
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