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akflyer

Joined: 07 May 2007
Posts: 574
Location: Soldotna AK

Posted: Thu Jan 22, 2009 11:45 pm Post subject: Re: 26 foot Clipped Wing Kitfox

 	  JetPilot wrote: 	
		   	  akflyer wrote: 	
		  



yeah  and short wing pipers don't fly either right????  The pacer clan of pipers has alot shorter wing than a cub or 12 etc.  They fly fine, in fact.



	




You are very wrong about that AKFlyer, the short wing Pipers have a horrible reputation, and rightfully so.  There is a really good reason manufacturers of modern airplanes have not imitated these short winged Pipers, and why the short winged pipers have not been produced in many many years and have never been copied ( Unlike the Piper Cub ).  So despite your " Flawed Reasoning " and somewhat appealing an nostalgic post relating to old pipers, what you say is just bad information.   I would hope most people here are smart enough to realize bad information even when it is presented by some slick, smoothing talking, snake oil salesman.



Given aerodynamic information available these days, it is a really bad idea to clip the wings that short.  Just look at the wingspans of most modern Light Sport Aircraft today, their wings have a pretty high aspect ratio, there is a very good reason for that.



Mike 	


Snake oil Salesman, LMAO  I am very sorry you can't fly, I can, do and LOVE it.



I flew 2 of them today, how about you ????? I have hundreds of hours in these and guess what, in the hands of a person who knows how to use their feet they are a GREAT airplane.  The guy that flew up with me to get this one today one has over 11,000 hours flying HARD CORE bush.  He will do things with a cub, beaver or turbine otter, what will scare the crap out of you AND I.  He fell in love and is now looking for one himself for his personal plane.... the long wing piper, such as a 180 horse cub are have their place in bush flying, nothing CERTIFIED will touch a cub for going into unimproved strips (read that big boulders or high tundra).  No one that owns a cub, that is not working it for hire would take the planes into the places he will, and there are only a very small handful that can follow him into the places he goes.



How many hours do you have in short wing piper???  What are YOU basing your statements on? hearsay, or personal hardcore flying facts?????



I make my post based on my time flying one in crap you could not imagine, and I stand VERY firm behind my statement.  Tell you what, drag your butt up here and I will take you out and show you what these planes are capable of.  8 yrs ago I set a new personal best, one that I get to poke my chest out on... A buddy had some friends come up from down south and wanted me to take them out flying and show them what we do.  I made the guy puke just doing what I do every day normal flying... I dropped into a short strip and let him get out and catch his breath... after he cleaned my plane up he shook my hand and said, well son I have to hand it to you, I have 27,000 hrs flying everything from 152's to 747 and 20 yrs in the navy flying combat from Vietnam to  Desert Storm and hundreds of night carrier traps... I have never been so damn nervous coming into such a short, nasty spots as you just did that it made me puke.... And what was I flying that day.... A stock 150 hrs Pacer.  I was not even going into anything that was remotely scary to me, but it impressed the heck out of him what could be done with the plane,as he, like you had heard horror stories about these planes.  Step away from the computer, get some bush hours in these plane, then get back to me just how bad they are.... In the mean time, I will go burn more sky tomorrow in a GASP nasty pacer and come back in grinning ear to ear about how cheap I can buy one cause guys like you cant fly.



All else, sorry for the rant, but I will only post what I have personally done, not hearsay.  Pics I tooks of and from these flying death traps today will follow.

Paul, as I said in the post above, clip those wings, then post a pictures and video of your "death trap" to hush the nay sayers.

_________________
DO NOT ARCHIVE
Leonard Perry aka SNAKE
Soldotna AK
Avid "C" / Mk IV
582 (147 hrs and counting on the rebuild)
IVO IFA
Full Lotus 1450
#1 snake oil salesman since 1-22-2009

I would rather die trying to live, than to live trying not to die....

Dick Maddux

Joined: 24 Jun 2008
Posts: 516
Location: Milton, Fl

Posted: Fri Jan 23, 2009 5:44 am Post subject: 26 foot Clipped Wing Kitfox

Mike,

  Where do you come up with your " facts" . I think you probably invent them. The short wing Pipers were absolutely fabulous aircraft and had no bad reputation at all. They have a higher sink rate yes but they fly great, are very economical, fast,etc. They were discontinued because of the economic times and changes in aircraft models. Have you ever flown one? They are the most bang for the buck you can find in a small production aircraft 

  If I am not mistaken, I believe Grummans,Rv's,Kr's,etc all have short wings and are also fine aircraft

                                                      Dick Maddux

                                                      Pensacola,Fl 

  

 From Wall Street to Main Street and everywhere in between, stay up-to-date with the [url=http://aol.com?ncid=emlcntaolcom00000023 ]latest news[/url].

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JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Fri Jan 23, 2009 7:59 am Post subject: Re: 26 foot Clipped Wing Kitfox

 	  av8rps wrote: 	
		  Hi Gang,



Oh yeah, I'm basing my rationale for doing this on what Avid did back in the early days when they took their 29+ foot Avid STOL wing off their airplane and made a new semi-symmetrical airfoil with only a 24 foot span.  



Paul S 	




Paul,



There is a big difference between making an entirely new wing, with a different airfoil optimized to be shorter, and just cutting the ends off of a wing that is designed to be much longer.  You should think about this hard before you think that just cutting the ends off the wing will make it a lot faster.  Did it ever occur to you that the new airfoil may have had more to do with the Avid's speed increase than just reducing the span ?



Changing airfoil AND span is far different than just cutting the ends off of a Kitfox wing.  Good luck with that, but you are in for a really big dissapointment.



Dick Maddux,



Maybe you like short wing Pipers, but most people did not.  Cessna kicked their butts with Higher aspect radio and longer span 150's and 172's.   Much more importantly to those considering modifying a Kitfox, they should look at moder LSA aircraft design, which is more comparable to a Kitfox, and has almost universally gone towards longer span, higher aspect ratio wings.  There is a very good reason for this, and that is a FACT.



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

mscotter

Joined: 15 Jan 2006
Posts: 49
Location: Winston-Salem, NC

Posted: Fri Jan 23, 2009 8:17 am Post subject: 26 foot Clipped Wing Kitfox

Hey Paul, just a thought, but this might be a good application for Michel's kitfox model in X-plane.  Perhaps if somebody sweet-talked him a little bit he'd be willing to make a copy of his kitfox model with the shortened wing that you're interested in and then compare the simulated performance of the two.  X-plane is a reasonably accurate simulation tool and especially with having two different models to compare and contrast (one with regular wing and one with shortened) he could get a good idea of the relative differences between the two.  



Just a thought. Like others have pointed out the real proof won't come til it's actually been flown in this configuration, but this simulation could provide some additional data points for consideration.  I am not an aerodynamicist, but in my engineer's brain your slow speed handling and climb performance would probably drop off slowly as you decrease span up until some minimum span is reached and then the decline would accelerate rapidly.  Hope that makes sense.



Mark Scott

Elkton, MD

 -------------- Original message ----------------------

From: "av8rps" <paul676(at)tds.net>

 	  Quote: 	
		   

 

 C'mon gang, let's keep this thread civil and productive.  And let's face it, 

 until one of us actually tries a 26 ft wing mod, none of us really knows what 

 the results will be.    

 

 I don't want to create big debates about all this, so maybe if I can better 

 explain my logic it will help everyone to better understand why I believe this 

 will work as I think it will;

 

 #1 - When Skystar clipped the standard Kitfox wing 3 ft to create the Speedster, 

 they found they increased the stall speed only minimally, lost very little climb 

 rate, but gained approximately 8-12 mph in speed.  That tells me that there is 

 apparently still plenty of wing area for the weight of the airplane.  

 

 #2 - If you do a wing loading calculation for a 650 lb model IV with the 26 ft 

 wing vs a 825 lb Model 5-7 Kitfox with a full length wing, the wing loadings for 

 both airplanes are virtually the same assuming the same cabin and fuel load (I 

 used 300 lbs for the example below). 

 

 Here's my math; 

 Model IV w/26 ft wing (at) 950 lbs -:- 107 sq ft = 8.8 lbs sq ft

 Model 7 w/32 ft wing (at) 1125 lbs -:- 131 sq ft = 8.6 lbs sq ft

 

 So, a 26 ft M4 does in fact have a similar wing loading to a newer Kitfox with 

 the longer, full span wing.  If the newer Fox had a Speedster 29' wing, it is 

 likely to have worse overall performance than the 26' M4.

 

 #3 - One of the most popular homebuilts ever created is the Van's RV series.  

 They are not only fast long distance cruisers, but also have relatively slow 

 stall speeds and good short field capability considering their high top speed 

 capability.  Statistically, an early RV-3 weighs 750 lbs empty, has a top speed 

 of 207 mph, a climb rate of 2050 fpm, and a stall speed of 51 mph.  All that on 

 a measly 19 ft wing with only 90 sq ft of area.  And if you look at any of the 

 other RV series airplanes, you will see similar information.  The longest wing 

 they use on any of their models is 28 ft, but ironically that model has a 30+ 

 slower top speed, a climb rate that is 1/2 that of the shorter wing models,  and 

 a stall speed that is only 3-5 mph slower than the short wings.  So much for 

 thinking you can't have a short wing airplane perform well for a wide speed 

 range.  The popularity of the RV series is testimony to that, as they are highly 

 regarded for their excellent handling and out!

  standing performance.  

 

 #4 - The crude "guess-timate" I came up with for performance is based primarily 

 on information I took out of a book titled "Design for Flying", written by David 

 Thurston, a Grumman aircraft designer that is best known for having designed the 

 Lake Amphibian.  I own a Lake Amphibian in addition to my Kitfoxes, and after 

 having put 900+ hours on it, I have a huge respect for Mr. Thurstons  design and 

 engineering abilities (a Lake is a very complex, but efficient design).  So I am 

 pretty confident my basic information and theory on this Kitfox wing 

 modification is reasonably well founded.

 

 Once again, I don't mean to cause any big heated debates over this idea.  I just 

 thought it would be neat to get some input from the group before I start cutting 

 spar tubes.

 

 Paul

_________________
Mark Scott
Winston-Salem, NC

Guy Buchanan

Joined: 16 Jul 2006
Posts: 1204
Location: Ramona, CA

Posted: Fri Jan 23, 2009 8:56 am Post subject: 26 foot Clipped Wing Kitfox

At 11:45 PM 1/22/2009, you wrote:

 	  Quote: 	
		  All else, sorry for the rant, but I will only post what I have 

personally done, not hearsay.  Pics I tooks of and from these flying 

death traps today will follow.


	


         OK guys. As much as I like to talk airplanes, I'm going to 

encourage all of you to let the Piper thread peter-out. (I know it's 

fun, and sort-of Kitfox related so if you just HAVE to say something, 

go ahead. But let's not prolong it too much.) And please do not 

continue to respond to Mike's original post. He and I are 

"discussing" it off-line.



Thanks,

Guy Buchanan

San Diego, CA

K-IV 1200 / 582-C / Warp / 100% done, thanks mostly to Bob Ducar.

_________________
Guy Buchanan
Deceased K-IV 1200
A glider pilot too.

Guy Buchanan

Joined: 16 Jul 2006
Posts: 1204
Location: Ramona, CA

Posted: Fri Jan 23, 2009 9:04 am Post subject: 26 foot Clipped Wing Kitfox

Sorry. Wrong signature.



At 08:49 AM 1/23/2009, you wrote:

 	  Quote: 	
		  At 11:45 PM 1/22/2009, you wrote:

>All else, sorry for the rant, but I will only post what I have 

>personally done, not hearsay.  Pics I tooks of and from these 

>flying death traps today will follow.



         OK guys. As much as I like to talk airplanes, I'm going to 

 encourage all of you to let the Piper thread peter-out. (I know 

 it's fun, and sort-of Kitfox related so if you just HAVE to say 

 something, go ahead. But let's not prolong it too much.) And please 

 do not continue to respond to Mike's original post. He and I are 

 "discussing" it off-line.



Thanks,



Guy Buchanan

San Diego, CA

K-IV 1200 / 582-C / Warp / 100% done, thanks mostly to Bob Ducar.


	


Guy Buchanan, Kitfox List Moderator

San Diego, CA

K-IV 1200 / 582-C / Warp / 100% done, thanks mostly to Bob Ducar.

_________________
Guy Buchanan
Deceased K-IV 1200
A glider pilot too.

lcfitt(at)sbcglobal.net
Guest

Posted: Fri Jan 23, 2009 9:23 am Post subject: 26 foot Clipped Wing Kitfox

Hi Mike,



I think you are making a mistake comparing a LSA to a clipped wing Kitfox. 

The whole LSA program, is directed at a new, low time, pilot (such as 

yourself maybe).  Some of us old timers are taking advantage of the program 

medical wise, but that doesn't change the reason it was introduced.  If your 

concept of aircraft is like a bicycle with training wheels - I can't fault 

that, but I do wonder on your insistance that others do the same or somehow 

they are stupid.



Regarding airfoils.  I think that if you did a little digging, you would 

find that an airfoil is designed with lift, stall characteristics and other 

factors such as feeding the moving air to the flaps, ailerons etc.  It is a 

quite narrow consideration and doesn't consider wing length.  I know of 

several designs that have different airfoil profiles on different parts of 

the wing with specific design characteristics needed for that section of 

wing.  Some are definitely buggers to fly, but then they are not intended 

for the 100 hour pilot to get time in.  Frankly, the 100 hour pilot wouldn't 

exist in those airplanes because they probably wouldn't survive their first 

landing.   If you are afraid of flying these airplanes, you have company as 

I am as well, but with the proper training and experience they meet their 

design criteria and are perfectly safe to fly.  If shortening the Riblett 

airfoil used on the Kitfox was a no no, then the factory would have never 

introduced the Speedster.



What mystifies me is how you have the inclination to project your fear of 

flying to everyone on the list.  If I was as fearful of anything but 172s as 

You seem to be, I think I would keep it pretty much to myself.



You have dissed tailwheels and short wings because of perceived fears.  I am 

all eyes waiting for what else scares you and for feeling stupid if I don't 

share the fears.



Lowell



---

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Fri Jan 23, 2009 10:37 am Post subject: Re: 26 foot Clipped Wing Kitfox

 	  lcfitt(at)sbcglobal.net wrote: 	
		  Hi Mike,



You have dissed tailwheels and short wings because of perceived fears.  I am 

all eyes waiting for what else scares you and for feeling stupid if I don't 

share the fears.



Lowell



--- 	




Lowell,



You are just trying to distract people from the facts when you try to talk about " Fear ".    You know full well that the main point of my several posts relating to this subject is that Shortening the wings by this large amount will hurt the performance of the Kitfox, and that the significant amount of speed increase, if any, that the author is hoping for will not happen.   So if you have information or facts that says that the Kitfox will perform better with such short wings, then by all means post it.  If the best you can do is try to distract readers from the facts with " Fear ", then that is pretty pathetic on your part.



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

Dick Maddux

Joined: 24 Jun 2008
Posts: 516
Location: Milton, Fl

Posted: Sat Jan 24, 2009 6:17 am Post subject: 26 foot Clipped Wing Kitfox

Well, Lowell, junior's at it again. Maybe we are missing the boat. He might be a rocket scientist or senior aeronautical engineer.

                                      Dick Maddux

                                      Pensacola,Fl   

 From Wall Street to Main Street and everywhere in between, stay up-to-date with the [url=http://aol.com?ncid=emlcntaolcom00000023 ]latest news[/url].

  [quote][b]

akflyer

Joined: 07 May 2007
Posts: 574
Location: Soldotna AK

Posted: Sat Jan 24, 2009 10:11 am Post subject: Re: 26 foot Clipped Wing Kitfox

[quote="Dick Maddux"]Well, Lowell, junior's at it again. Maybe we are missing the boat. He might be a rocket scientist or senior aeronautical engineer.

            ï¿½            ï¿½            Dick Maddux

            ï¿½            ï¿½            Pensacola,Fl   

 From Wall Street to Main Street and everywhere in between, stay up-to-date with the [url=http://aol.com?ncid=emlcntaolcom00000023 ]latest news[/url].

   	  Quote: 	
		  [b] 	




I think a whole category was created for this one... a rocket SURGEON.

kitfoxfugit(at)yahoo.com
Guest

Posted: Sat Jan 24, 2009 10:42 pm Post subject: 26 foot Clipped Wing Kitfox

I don't want to get into an argument over this, because everyone has their own opinions, but will relate what I know.



I have flown a PA-22 Pacer with 180 HP and large tires.  It files fine into and out of gravel bars and small bush strips.  I can't compare it with a Super Cub for that because it has been too long since I have flown a PA-18.  I like the PA-18 much better for its tandem seating, stick, split door that opens in flight, better visibility, and easier to reach flap handle.  But the Pacer is a good, honest airplane, nice to fly, much faster than the PA-18 in cruise, and can carry four people.  And half the price, or less.



My Speedster flies fine with the standard Speedster wing.  It is light on the controls, has an excellent roll rate, gets off quickly, climbs at a good rate, and is economical with 87 Octane autogas fuel burns from 2.5 GPH putting around to 5 GPH on long cross-countries.  It has climbed over the Sierras and Rockies fully loaded with plenty of clearance (right over the mountains, no need to go through passes), and it cruises at a decent speed with such range and stability that it can make long trips easily.  It can land very short and has used many gravel strips with its 6.00 x 6 tires and Maule tailwheel (which does shimmey some on pavement).



I can't compare it with a standard Model IV, because I have never flown one or alongside one. Its cruise speed is 10 MPH faster than that reported by the owner of a longer-wing version in our area that is otherwise set up exactly the same.  It has flown with a Super Cub just fine (but won't carry the same load). At high elevations, heavily loaded, on a hot day, and also at high elevations on wet grass, it does take some runway to get off.  Once off, it climbs fine.  The longer wing should have a stall speed lower than 45 mph and may be better for high-elevation strips or for pure bush flying, with really short strips.  My only complaints are the side-by side seating, the poor forward visibility, the cramped cabin, the lack of luggage capacity, and the wing is too low to stand up out of the rain. The best feature is the folding wings.



JA KF IV Speedster (at) O70

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Sun Jan 25, 2009 10:14 am Post subject: Re: 26 foot Clipped Wing Kitfox

 	  Dick Maddux wrote: 	
		  Well, Lowell, junior's at it again. Maybe we are missing the boat. He might be a rocket scientist or senior aeronautical engineer.

 	




Dick,



The only comments you or Lowell have posted in relation to the subject of cutting a Kitfox wings to 26 feet have nothing to do with the subject at hand.  Lowell only tried to distract people away from the facts with his post, and your post has zero information on this subject, and does is nothing other than try to belittle me.  If you think I am wrong and am giving Paul bad advice, lets hear why.  A childish and uncalled for comment like you just posted just reflects very badly on you.  You being an ex military and airline pilot, I really expected you to post something far more intelligent and informative on this subject than this. You are not the person I thought you were.



What Paul needs is good information on the likely results of clipping his Kitfox wings down to 26 feet.   If you disagree with me, post some factual information as to why, and something that can help anyone that is thinking about shortening the wingspan of their Kitfox make an informed decision.   This is a good subject and it should be kept on topic.



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

eskflyer

Joined: 24 May 2007
Posts: 44
Location: AK

Posted: Sun Jan 25, 2009 11:34 am Post subject: Re: 26 foot Clipped Wing Kitfox

UHHH Rocket dude . Are you a expert who can say that 26 foot wing is bad , Have you done this and verified how horrible it will be in your opinion . 

 I to fly a short wing PIPER and love it . PA22/20 with 150 HP . Absolutely no bad habits at all. Now i did own a kitfox and darn you cant see over the dash when the tail is down . Is that a horrible problem Gee how many have ground looped a kitfox ?. Does this make the Kitfox a horrible plane ?. No it does not at all. they both are a rudder plane you stay on your toes or you might be on your nose. 



That being said i think you need need to pull your head out and breath some fresh air Mike . 



OK i know i will be banned again lol. 



John N3579erA

_________________
FLY FUN FLY LOW FLY SLOW
John Perry
Kitfox 2 N718PD
582 cbox 2:62-1 IVO IFA
1220 Full Lotus

lcfitt(at)sbcglobal.net
Guest

Posted: Sun Jan 25, 2009 12:07 pm Post subject: 26 foot Clipped Wing Kitfox

Comeon Mike,



There is no good information on Paul's plan. Paul is an experimenter. 

Nobody has gone on before, so no one has anything to say.  He has an idea 

and wants to persue it.  Your "good information" about how bad the Tripacer 

and Pacer fly has been soundly debunked by a number of experienced list 

members so your "good information" is worth less than junk.  I spent a 

couple of hours this morning on the web reading about airfoils.  It would 

take an aeronotical engineer to predict what the increased wing loading 

would do to performance.  That is all the clipping would do, increase wing 

loading and possibly the angle of attack. And I suspect what the unnamed 

aeronotical engineer would do is put the numbers in his computer and it 

would spit out the results.  That said though, I suspect if he had 

significant airfoil design experience he could likely predict trends.



As for you and me, trying to do the same by using hangar talk, aircraft 

history (Piper TriPacer - different airfoil to be sure), or any other 

irrelivent nonsense neither helps Paul nor is it informative to list 

members.  That is why I haven't commented on his plans, and I respectfully 

invite you to refrain as well.  It might surprise you that you are the only 

one reading these posts that think your comments have any relevency.



Lowell

---

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Sun Jan 25, 2009 1:24 pm Post subject: 26 foot Clipped Wing Kitfox

Hey John...long time no hear from. You gave me much-needed advice  

when I built my first set of skis (when you were in Oklahoma?  

Kansas? ) Just finished another pair, and they work fine too.



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 600.2 hrs

Sensenich 62x46

Electroair direct-fire ignition system

New skis done and flying

do not archive



On Jan 25, 2009, at 2:34 PM, eskflyer wrote:



 	  Quote: 	
		   



 UHHH Rocket dude . Are you a expert who can say that 26 foot wing  

 is bad , Have you done this and verified how horrible it will be in  

 your opinion .

  I to fly a short wing PIPER and love it . PA22/20 with 150 HP .  

 Absolutely no bad habits at all. Now i did own a kitfox and darn  

 you cant see over the dash when the tail is down . Is that a  

 horrible problem Gee how many have ground looped a kitfox ?. Does  

 this make the Kitfox a horrible plane ?. No it does not at all.  

 they both are a rudder plane you stay on your toes or you might be  

 on your nose.



 That being said i think you need need to pull your head out and  

 breath some fresh air Mike .



 OK i know i will be banned again lol.



 John N3579erA



 --------

 FLY FUN FLY LOW FLY SLOW

 John Perry

 Kitfox 2 N718PD

 582 cbox 2:62-1 IVO IFA

 1220 Full Lotus





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p 26741#226741

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

av8rps

Joined: 05 Jan 2008
Posts: 33
Location: Central Wisconsin

Posted: Sun Jan 25, 2009 8:50 pm Post subject: Re: 26 foot Clipped Wing Kitfox

Hey Gang,



I'm sorry for causing such a stir over my idea of clipping the wings on my Kitfox.  Causing arguments between my Kitfox pals was the last thing I intended.  I was just looking for some good input.



And honestly, I really do appreciate all the comments I received, whether perceived by some as good, or bad.  And for those of you that think I am nuts for even thinking of doing this, well... I appreciate your concern.  But I'm going to go ahead with my idea.  As many of us have said, it is an experiment and no one will know until one of us does it.  And since cutting the tips off is only a temporary measure (as long as I make the tips re-installable like I had planned), it shouldn't be a big deal even if it doesn't work out.  



OK, maybe the first test flight with the short wing could prove interesting, but I really don't think that will be the case.  And even if it does, I've been flying Avids and Kitfoxes since the mid 80's, and after accumlating nearly 3,000 hours in them in just about every possible configuration they come in, I haven't found anything scary about one of them yet.  In a worse case scenario, the slightly shorter wing will at minimum prove to be educational. (smile)



Regarding the discussion about airfoil selection, I found this about the RV lineups airfoils;    



RV Airfoil info 

 

From the very first iteration the RV-3 has always used the 23012 airfoil. All the two-seat short wing RVs (-4, -6, -7 and - use the 23013.5.  All the 23000 series airfoils have the same basic shape, the only difference in these airfoils is the thickness. The thickness is given by the last digits. The 23012 airfoil is 12% thick (i.e. the maximum thickness is 12% of the wing chord) while the 23013.5 is 13.5% thick.     The 23000 series is extremely widely used, on everything from Taylorcrafts to Cessna Citations, so RVs are in good company.        When the -3B wing was introduced in 1998 it retained the 23012 airfoil but featured a new internal structure. The trade-offs that Van made when selecting 13.5% thickness for the RV-4 (and subsequent 2 seat designs except RV-9) versus the 12% from the RV-3 were a fairly sizeable structural benefit (varies as the cube of spar depth) against a small increase in section drag... really a hair-splitter in the speed realm that RV's typically operate. Section drag doesn't start to become a very big deal until you get above roughly 15% thick.



I just thought that was interesting in light of our conversations about airfoils and wings.



I'll be out in the shop with my Sawzall if anyone is looking for me...



Paul

_________________
Model IV-1200 912ul Amphib
Avid Flyer Sn#1 and Sn#26
Highlander 912s taildragger
Lake Amphibian
Central Wisconsin
paul676@tds.net

gary.algate(at)sandvik.co
Guest

Posted: Sun Jan 25, 2009 9:35 pm Post subject: 26 foot Clipped Wing Kitfox

hey Paul 

 

Keep us updated - I still have my old skill saw and if you get really good results I might have to consider clipping my clipped wing - hmm make it easy to get in the hanger too 

 

regards 

 

Gary

 

 Gary Algate

 SMC, Exploration

 Office Phone: +61 8 8276 7655

 

 

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"av8rps" <paul676(at)tds.net> 

Sent by: owner-kitfox-list-server(at)matronics.com 

26/01/2009 03:53 PM 

Please respond to

 kitfox-list(at)matronics.com     To

 kitfox-list(at)matronics.com   cc

    Subject

 Re: 26 foot Clipped Wing Kitfox 

     

 

 

 

--> Kitfox-List message posted by: "av8rps" <paul676(at)tds.net>

 

 Hey Gang,

 

 I'm sorry for causing such a stir over my idea of clipping the wings on my Kitfox.  Causing arguments between my Kitfox pals was the last thing I intended.  I was just looking for some good input.

 

 And honestly, I really do appreciate all the comments I received, whether perceived by some as good, or bad.  And for those of you that think I am nuts for even thinking of doing this, well... I appreciate your concern.  But I'm going to go ahead with my idea.  As many of us have said, it is an experiment and no one will know until one of us does it.  And since cutting the tips off is only a temporary measure (as long as I make the tips re-installable like I had planned), it shouldn't be a big deal even if it doesn't work out.  

 

 OK, maybe the first test flight with the short wing could prove interesting, but I really don't think that will be the case.  And even if it does, I've been flying Avids and Kitfoxes since the mid 80's, and after accumlating nearly 3,000 hours in them in just about every possible configuration they come in, I haven't found anything scary about one of them yet.  In a worse case scenario, the slightly shorter wing will at minimum prove to be educational. (smile)

 

 Regarding the discussion about airfoil selection, I found this about the RV lineups airfoils;    

 

 RV Airfoil info 

  

 >From the very first iteration the RV-3 has always used the 23012 airfoil. All the two-seat short wing RVs (-4, -6, -7 and - use the 23013.5.  All the 23000 series airfoils have the same basic shape, the only difference in these airfoils is the thickness. The thickness is given by the last digits. The 23012 airfoil is 12% thick (i.e. the maximum thickness is 12% of the wing chord) while the 23013.5 is 13.5% thick.     The 23000 series is extremely widely used, on everything from Taylorcrafts to Cessna Citations, so RVs are in good company.        When the -3B wing was introduced in 1998 it retained the 23012 airfoil but featured a new internal structure. The trade-offs that Van made when selecting 13.5% thickness for the RV-4 (and subsequent 2 seat designs except RV-9) versus the 12% from the RV-3 were a fairly sizeable structural benefit (varies as the cube of spar depth) against a small increase in section drag... really a hair-splitter in the speed realm that RV's typic!

  ally operate. Section drag doesn't start to become a very big deal until you get above roughly 15% thick.

 

 I just thought that was interesting in light of our conversations about airfoils and wings.

 

 I'll be out in the shop with my Sawzall if anyone is looking for me...

 

 Paul

 

 --------

 Model IV-1200 912ul Amphib

 Avid Flyer

 Lake Amphibian

 Central Wisconsin

 paul676(at)tds.net

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=226815#226815

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Mon Jan 26, 2009 9:12 am Post subject: 26 foot Clipped Wing Kitfox

With the quick disconnect feature of the Kitfox flapperon controls i would

hav advised to build a set of short wings...  I think it would be easier to

swap a set of wings than to play around trying to get control surfaces to

stretch.  Two guys could swap out a set of wings in less than an hour.  If

the shorter wings turn out well sell the longer ones to someone who wants to

finish their plane faster.



If they don't work the way hoped then there is a good set of wings to

experiment on...  VGs, wing tips, etc.



Noel



--

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Mon Jan 26, 2009 2:11 pm Post subject: Re: 26 foot Clipped Wing Kitfox

Paul,



Good luck with your " Experiment ", don't feel bad for throwing it out here on the forum, this is exactly why we are all here.  Not your fault if the discussion got a little lively   I don't think you will get the performance increase you hope for, but it does not sound dangerous to try something like this.  Just a lot of time and some money invested.  The removable wing tips are a GREAT idea, you are going to want those to compensate for that overly short wing !  There is a Brazilian motor glider that uses removable wingtips for different types of flying.  I look forward to your results.



For those that keep going back to short wing Pipers, you seem to have forgotten that those short Piper wings were DESIGNED FROM THE START to be short, and have a WIDE CHORD and other things such as DIFFERENT AIRFOILS to compensate for this.   You all have gotten distracted by Pipers, we are not talking about a Piper wing here, we are talking about cutting down a Kitfox wing.  Just because you may like the way a Piper flys, to use this is a basis for cutting a Kitfox wing's down to 26 feet and say it should perform better is nothing short of foolish.



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

Fox5flyer
Guest

Posted: Mon Jan 26, 2009 3:23 pm Post subject: 26 foot Clipped Wing Kitfox

Uh, maybe I'm being a little bit senile here, but if I recall correctly, 

Kitfox has had removable wing tips for a very long time.  I'm talking about 

the option where one can have a speedster one day and a long wing the next. 

I recall that several members have used this option, but most ended up just 

picking one or the other and leaving it that way.  I have no idea if the 

option is still available.  John McBean?

Deke Morisse

Mikado Michigan

S5/Subaru/CAP 402+ TT

"The aim of an argument or discussion should not be victory, but progress."

- Joseph Joubert

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