Kolb-List Digest Archive

Sat 03/19/16


Total Messages Posted: 7



Today's Message Index:
----------------------
 
     1. 03:59 AM - long legs (Patrick Ladd)
     2. 04:25 AM - Re: long legs (Richard Pike)
     3. 06:34 AM - Re: long legs (Charlie England)
     4. 06:46 AM - Re: long legs (Dennis Rowe)
     5. 07:40 AM - Re: long legs (Patrick Ladd)
     6. 08:28 AM - Re: long legs (Charlie England)
     7. 10:18 AM - Re: Re: long legs (Patrick Ladd)
 
 
 


Message 1


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    Time: 03:59:09 AM PST US
    From: Patrick Ladd <patrickjladd@hotmail.com>
    Subject: long legs
    I may be sticking my neck out here and asking get slapped down but will someone explain why having longer legs increases the STOL capability of our a/c. Excepting of course the case where you deliberately hold the tail down on take off. I agree with all the advantages which John listed, more wing area exposed thus slowing landing run etc. However the first thing which most of us do on take off is to get the tail up into flying position thus reducing drag and allowing increased acceleration. When the tail is up the the length of the u/c is irrelevant. In fact having the extra wing area exposed by having long legs slows the planes acceleration for exactly the same reason that it shortens the landing run. When the plane is up on two wheels the AOA is that which was designed in. Comments about commercial a/c are largely irrelevant as they are (mainly) tricycle gear and the wing is in flying position (more or less) the whole time. There may be good reasons for making u/c legs longer but I am not convinced that STOL is one of them except the `keep the skid on the ground until she drags herself off` scenario which I mentioned.. Enlightenment please. Pat


    Message 2


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    Time: 04:25:14 AM PST US
    Subject: Re: long legs
    From: "Richard Pike" <thegreybaron@charter.net>
    Make the gear legs long enough and your fat friends will not be able to get in. Which enables the airplane to get off the ground quicker. Glad to help out. -------- Richard Pike Kolb MKIII N420P (420ldPoops) Kingsport, TN 3TN0 Would you consider yourself to be a good person? https://www.youtube.com/watch?v=VWcDXT6pH7A Read this topic online here: http://forums.matronics.com/viewtopic.php?p=453919#453919


    Message 3


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    Time: 06:34:47 AM PST US
    Subject: Re: long legs
    From: Charlie England <ceengland7@gmail.com>
    On Sat, Mar 19, 2016 at 5:58 AM, Patrick Ladd <patrickjladd@hotmail.com> wrote: > I may be sticking my neck out here and asking get slapped down but will > someone explain why having longer legs increases the STOL capability of our > a/c. Excepting of course the case where you deliberately hold the tail down > on take off. > I agree with all the advantages which John listed, more wing area exposed > thus slowing landing run etc. However the first thing which most of us do > on take off is to get the tail up into flying position thus reducing drag > and allowing increased acceleration. When the tail is up the the length of > the u/c is irrelevant. In fact having the extra wing area exposed by having > long legs slows the planes acceleration for exactly the same reason that it > shortens the landing run. > When the plane is up on two wheels the AOA is that which was designed in. > Comments about commercial a/c are largely irrelevant as they are (mainly) > tricycle gear and the wing is in flying position (more or less) the whole > time. > There may be good reasons for making u/c legs longer but I am not > convinced that STOL is one of them except the `keep the skid on the ground > until she drags herself off` scenario which I mentioned.. > Enlightenment please. > Pat > I'll take a crack at it, in general terms. You can decide if it applies to Kolbs. If you watch videos of hard core bush flying, the pilot will hold the brakes and raise the tail prior to starting the takeoff roll (to minimize wing drag, as you point out). When he's got max available power, he releases the brakes. As soon as he's got minimum flying speed, he rotates & the plane jumps into the air. Now, most taildraggers sit on the ground with the wing at a significantly lower angle than critical (stall) AOA. So in stock condition, they can't be rotated to lift off at anywhere near stall speed. So, their minimum speed for takeoff is limited (made higher) by the length of the main gear legs. If the same trick is tried with 'short legs', the pilot would slam the tailwheel into the ground when he rotates. FWIW, there are videos of airliners actually dragging the rear of the fuselage on the ground when they over-rotate. Airliners (at least some of them) actually give up significant landing speed reduction because they don't want the weight of long gear legs when they always have plenty of runway for 'driving it on' in landing. In landing mode, it's just as important. In normal flying, a pilot would try to '3 point', having the mains & tailwheel touch at the same time to land at minimum airspeed. But, since the wing isn't at critical AOA in 3 point attitude, he's not really landing at minimum airspeed. If the mains were longer, he could land slower. In bush flying, it gets worse. Again, watching extreme bush flying, you'll see the pilot wheel land and keep the tail off the ground until he's almost stopped. With a typical taildragger, he's carrying quite a bit of extra airspeed to 'wheel land' the plane, but he does it to protect the tailwheel from damage, from rough ground and from impact damage of dropping it in. If the legs are extended enough, he can have full stall AOA available from the wing, without the tailwheel being on the ground. Obviously, this will let him land slower & shorter. Does any of that apply to Kolbs?


    Message 4


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    Time: 06:46:43 AM PST US
    From: Dennis Rowe <rowedenny@windstream.net>
    Subject: Re: long legs
    Bingo on all points. Do not archive Dennis "Skid" Rowe > On Mar 19, 2016, at 9:34 AM, Charlie England <ceengland7@gmail.com> wrote: > > > >> On Sat, Mar 19, 2016 at 5:58 AM, Patrick Ladd <patrickjladd@hotmail.com> w rote: >> I may be sticking my neck out here and asking get slapped down but will s omeone explain why having longer legs increases the STOL capability of our a /c. Excepting of course the case where you deliberately hold the tail down o n take off. >> I agree with all the advantages which John listed, more wing area exposed thus slowing landing run etc. However the first thing which most of us do o n take off is to get the tail up into flying position thus reducing drag and allowing increased acceleration. When the tail is up the the length of the u /c is irrelevant. In fact having the extra wing area exposed by having long l egs slows the planes acceleration for exactly the same reason that it short ens the landing run. >> When the plane is up on two wheels the AOA is that which was designed in. >> Comments about commercial a/c are largely irrelevant as they are (mainly) tricycle gear and the wing is in flying position (more or less) the whole t ime. >> There may be good reasons for making u/c legs longer but I am not convinc ed that STOL is one of them except the `keep the skid on the ground until s he drags herself off` scenario which I mentioned.. >> Enlightenment please. >> Pat > > I'll take a crack at it, in general terms. You can decide if it applies to Kolbs. > > If you watch videos of hard core bush flying, the pilot will hold the brak es and raise the tail prior to starting the takeoff roll (to minimize wing d rag, as you point out). When he's got max available power, he releases the b rakes. As soon as he's got minimum flying speed, he rotates & the plane jump s into the air. Now, most taildraggers sit on the ground with the wing at a s ignificantly lower angle than critical (stall) AOA. So in stock condition, t hey can't be rotated to lift off at anywhere near stall speed. So, their min imum speed for takeoff is limited (made higher) by the length of the main ge ar legs. If the same trick is tried with 'short legs', the pilot would slam t he tailwheel into the ground when he rotates. FWIW, there are videos of airl iners actually dragging the rear of the fuselage on the ground when they ove r-rotate. Airliners (at least some of them) actually give up significant lan ding speed reduction because they don't want the weight of long gear legs wh en they always have plenty of runway for 'driving it on' in landing. > > In landing mode, it's just as important. In normal flying, a pilot would t ry to '3 point', having the mains & tailwheel touch at the same time to land at minimum airspeed. But, since the wing isn't at critical AOA in 3 point a ttitude, he's not really landing at minimum airspeed. If the mains were long er, he could land slower. In bush flying, it gets worse. Again, watching ext reme bush flying, you'll see the pilot wheel land and keep the tail off the g round until he's almost stopped. With a typical taildragger, he's carrying q uite a bit of extra airspeed to 'wheel land' the plane, but he does it to pr otect the tailwheel from damage, from rough ground and from impact damage of dropping it in. If the legs are extended enough, he can have full stall AOA available from the wing, without the tailwheel being on the ground. Obvious ly, this will let him land slower & shorter. > > Does any of that apply to Kolbs?


    Message 5


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    Time: 07:40:36 AM PST US
    From: Patrick Ladd <patrickjladd@hotmail.com>
    Subject: Re: long legs
    Thanks Charlie, i can see the reasoning and in fact I saw a guy up in Fairbanks in a Super Cub pulling the `tail up, full throttle trick`. He powered up, standing on the brakes, hauled it off the ground by pushing the tail down and climbing out at just above stall speed.. He did a circuit and landed again, tail down and hanging on his prop at full chat, like a helicopter. All in an incredibly short time. I filmed it with a video camera in one take. I somehow doubt that many Kolbers have the brakes, to be able to come close to emulating that performance. Without some actual measurements it is impossible to calculate accurately the increased AOA available and I was never any good at trig anyway but assuming 10ft between mains and tail wheel and an increase in height of the gear legs of say 4 inches, by how many degrees does that increase the AOA? 1 degree? 1.5 degrees.? No doubt someone on the list will work it out. It may well be worth extending legs for other reasons but STOL?. Questionable. Pat From: Charlie England Sent: Saturday, March 19, 2016 1:34 PM Subject: Re: Kolb-List: long legs On Sat, Mar 19, 2016 at 5:58 AM, Patrick Ladd <patrickjladd@hotmail.com> wrote: I may be sticking my neck out here and asking get slapped down but will someone explain why having longer legs increases the STOL capability of our a/c. Excepting of course the case where you deliberately hold the tail down on take off. I agree with all the advantages which John listed, more wing area exposed thus slowing landing run etc. However the first thing which most of us do on take off is to get the tail up into flying position thus reducing drag and allowing increased acceleration. When the tail is up the the length of the u/c is irrelevant. In fact having the extra wing area exposed by having long legs slows the planes acceleration for exactly the same reason that it shortens the landing run. When the plane is up on two wheels the AOA is that which was designed in. Comments about commercial a/c are largely irrelevant as they are (mainly) tricycle gear and the wing is in flying position (more or less) the whole time. There may be good reasons for making u/c legs longer but I am not convinced that STOL is one of them except the `keep the skid on the ground until she drags herself off` scenario which I mentioned.. Enlightenment please. Pat I'll take a crack at it, in general terms. You can decide if it applies to Kolbs. If you watch videos of hard core bush flying, the pilot will hold the brakes and raise the tail prior to starting the takeoff roll (to minimize wing drag, as you point out). When he's got max available power, he releases the brakes. As soon as he's got minimum flying speed, he rotates & the plane jumps into the air. Now, most taildraggers sit on the ground with the wing at a significantly lower angle than critical (stall) AOA. So in stock condition, they can't be rotated to lift off at anywhere near stall speed. So, their minimum speed for takeoff is limited (made higher) by the length of the main gear legs. If the same trick is tried with 'short legs', the pilot would slam the tailwheel into the ground when he rotates. FWIW, there are videos of airliners actually dragging the rear of the fuselage on the ground when they over-rotate. Airliners (at least some of them) actually give up significant landing speed reduction because they don't want the weight of long gear legs when they always have plenty of runway for 'driving it on' in landing. In landing mode, it's just as important. In normal flying, a pilot would try to '3 point', having the mains & tailwheel touch at the same time to land at minimum airspeed. But, since the wing isn't at critical AOA in 3 point attitude, he's not really landing at minimum airspeed. If the mains were longer, he could land slower. In bush flying, it gets worse. Again, watching extreme bush flying, you'll see the pilot wheel land and keep the tail off the ground until he's almost stopped. With a typical taildragger, he's carrying quite a bit of extra airspeed to 'wheel land' the plane, but he does it to protect the tailwheel from damage, from rough ground and from impact damage of dropping it in. If the legs are extended enough, he can have full stall AOA available from the wing, without the tailwheel being on the ground. Obviously, this will let him land slower & shorter. Does any of that apply to Kolbs?


    Message 6


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    Time: 08:28:12 AM PST US
    Subject: Re: long legs
    From: Charlie England <ceengland7@gmail.com>
    Since typical AOA is around 14-15 degrees at stall, a 1.5 degree increase could be close to a 10% increase in 3 point attitude. Not something to sneeze at. Again, you must decide if it applies to Kolbs, and whether it actually matters to you for your style of flying. Who would think that a stock Super Cub needed shorter field performance, but a lot of bush fliers obviously consider it inadequate for their purposes. On Sat, Mar 19, 2016 at 9:40 AM, Patrick Ladd <patrickjladd@hotmail.com> wrote: > Thanks Charlie, > i can see the reasoning and in fact I saw a guy up in Fairbanks in a Super > Cub pulling the `tail up, full throttle trick`. He powered up, standing on > the brakes, hauled it off the ground by pushing the tail down and climbing > out at just above stall speed.. He did a circuit and landed again, tail > down and hanging on his prop at full chat, like a helicopter. All in an > incredibly short time. I filmed it with a video camera in one take. > I somehow doubt that many Kolbers have the brakes, to be able to come > close to emulating that performance. Without some actual measurements it is > impossible to calculate accurately the increased AOA available and I was > never any good at trig anyway but assuming 10ft between mains and tail > wheel and an increase in height of the gear legs of say 4 inches, by how > many degrees does that increase the AOA? 1 degree? 1.5 degrees.? No doubt > someone on the list will work it out. > It may well be worth extending legs for other reasons but STOL?. > Questionable. > > Pat > > *From:* Charlie England <ceengland7@gmail.com> > *Sent:* Saturday, March 19, 2016 1:34 PM > *To:* kolb-list@matronics.com > *Subject:* Re: Kolb-List: long legs > > > On Sat, Mar 19, 2016 at 5:58 AM, Patrick Ladd <patrickjladd@hotmail.com> > wrote: > >> I may be sticking my neck out here and asking get slapped down but will >> someone explain why having longer legs increases the STOL capability of our >> a/c. Excepting of course the case where you deliberately hold the tail down >> on take off. >> I agree with all the advantages which John listed, more wing area exposed >> thus slowing landing run etc. However the first thing which most of us do >> on take off is to get the tail up into flying position thus reducing drag >> and allowing increased acceleration. When the tail is up the the length of >> the u/c is irrelevant. In fact having the extra wing area exposed by having >> long legs slows the planes acceleration for exactly the same reason that it >> shortens the landing run. >> When the plane is up on two wheels the AOA is that which was designed in. >> Comments about commercial a/c are largely irrelevant as they are (mainly) >> tricycle gear and the wing is in flying position (more or less) the whole >> time. >> There may be good reasons for making u/c legs longer but I am not >> convinced that STOL is one of them except the `keep the skid on the ground >> until she drags herself off` scenario which I mentioned.. >> Enlightenment please. >> Pat >> > > I'll take a crack at it, in general terms. You can decide if it applies to > Kolbs. > > If you watch videos of hard core bush flying, the pilot will hold the > brakes and raise the tail prior to starting the takeoff roll (to minimize > wing drag, as you point out). When he's got max available power, he > releases the brakes. As soon as he's got minimum flying speed, he rotates & > the plane jumps into the air. Now, most taildraggers sit on the ground with > the wing at a significantly lower angle than critical (stall) AOA. So in > stock condition, they can't be rotated to lift off at anywhere near stall > speed. So, their minimum speed for takeoff is limited (made higher) by the > length of the main gear legs. If the same trick is tried with 'short legs', > the pilot would slam the tailwheel into the ground when he rotates. FWIW, > there are videos of airliners actually dragging the rear of the fuselage on > the ground when they over-rotate. Airliners (at least some of them) > actually give up significant landing speed reduction because they don't > want the weight of long gear legs when they always have plenty of runway > for 'driving it on' in landing. > > In landing mode, it's just as important. In normal flying, a pilot would > try to '3 point', having the mains & tailwheel touch at the same time to > land at minimum airspeed. But, since the wing isn't at critical AOA in 3 > point attitude, he's not really landing at minimum airspeed. If the mains > were longer, he could land slower. In bush flying, it gets worse. Again, > watching extreme bush flying, you'll see the pilot wheel land and keep the > tail off the ground until he's almost stopped. With a typical taildragger, > he's carrying quite a bit of extra airspeed to 'wheel land' the plane, but > he does it to protect the tailwheel from damage, from rough ground and from > impact damage of dropping it in. If the legs are extended enough, he can > have full stall AOA available from the wing, without the tailwheel being on > the ground. Obviously, this will let him land slower & shorter. > > Does any of that apply to Kolbs? >


    Message 7


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    Time: 10:18:14 AM PST US
    From: Patrick Ladd <patrickjladd@hotmail.com>
    Subject: Re: long legs
    Good point Richard. In general my fat friends did not get a look in. Fat girls now.....Pat -----Original Message----- From: Richard Pike Sent: Saturday, March 19, 2016 11:24 AM Subject: Kolb-List: Re: long legs Make the gear legs long enough and your fat friends will not be able to get in. Which enables the airplane to get off the ground quicker. Glad to help out. -------- Richard Pike Kolb MKIII N420P (420ldPoops) Kingsport, TN 3TN0 Would you consider yourself to be a good person? https://www.youtube.com/watch?v=VWcDXT6pH7A Read this topic online here: http://forums.matronics.com/viewtopic.php?p=453919#453919




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