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williamtsullivan(at)att.n
Guest

Posted: Tue Aug 05, 2008 5:53 am Post subject: safety experiment

Richard Stracke's recent posting started me wondering how many people have had a similar experience with an unintentional lift-off in a Kolb.  I had attributed my accidental take-off to a gust, but Richard's use of the term "ballooning" seems to be a more appropriate term.  I had been taxiing for engine testing, going at what I thought was a moderate, controllable speed.  Probably about the same as one would use going down a taxi-way to the other end of a runway.  I had been having engine trouble, with several distinct problems.  At idle, there was a very heavy vibration- a shaking- that smoothed out above 2500 rpm.  When I taxied the length of the runway- 900 feet or so- , and then went back to idle, the engine would "load up" and not promptly respond to throttle advance for a few seconds.  Or, it would go the other way, and reduce rpms to 1400 or so, and nor respond at all until I shut it down and re-started.  At the  north end of the field, a couple of hundred feet from the end,  there was an area that was slightly down hill, and would cause the plane to noticeably accelerate, even at idle.  Sometimes I would have to shut off the motor to slow down enough to make my u-turn.  I am not sure, but I think this is where my event occurred.  My memory of all of it is still very shaky, more like a series of pictures than a flow of events.

    In order to help others stay away from a similar problem, I would like to enlist some help from the experienced members of the List.  How slowly can someone make a very light Firestar take off?  Or for that matter, what is the slowest lift-off speed of any of the Kolbs?  My Firestar lifted off with a gross weight of about 475 lbs. , and about 2700rpm.  What could be indicators of an imminent lift-off?  How can ground speed be determined prior to such an event?  Can a few of you take  your plane and, on a long, safe area, carefully induce the plane off the ground and report the speeds and conditions?  Maybe a GPS to determine it.

   

                                                  Thanks

                                                           

                                                        Bill Sullivan 

 [quote][b]

NeilsenRM(at)comcast.net
Guest

Posted: Tue Aug 05, 2008 6:51 am Post subject: safety experiment

William

  

 I have done this many times. It is a feature of all  the current models of Kolb aircraft. Reduce the power any way you choose to when  near flying speed and it will lift off. As I have said before some people have  used this as a way to pop off the ground. Abruptly reducing the power while fast  taxing will result in a very abrupt pitch up trim and it will get you air born.  Someone that is inexperienced in this feature will get themselves in  trouble doing this. I was taught in my private pilot training to taxi at a fast  "walking" speed. This is a good rule for a Kolb. These planes fly very well and  will reward you with flight if they get the chance. Never fast taxi if your  aren't ready to fly.

  

 Also I think it is a very very bad idea to "crow  hop" these airplanes as a way learning to fly.

  

 Again this is worth what you paid for  it.

  

 Rick Neilsen

 Redrive VW powered MKIIIC

 [quote]   ---

jlsk1(at)frontiernet.net
Guest

Posted: Tue Aug 05, 2008 9:53 am Post subject: safety experiment

William, I agree with Rick on all of his comments  here, and add, that nothing takes the place of some qualified dual instruction  in a Kolb, when transitioning from something else to a Kolb.

 Jim

 Cookeville, TN

 MK-3C

 [quote]   ---

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Tue Aug 05, 2008 9:53 am Post subject: safety experiment

Bill,



Many pilots have found themselves accidentally airborne.  Probably the more 

common scenario is to wreck trying to get it down on the remaining runway, 

rather than losing it on a landing attempt after going around the 

pattern.  A related (and just as bad) situation is getting too high, or too 

far off the runway centerline, on an intentional crow hop.



The minimum speed at which any aircraft will take off is, of course, its 

stall speed.  For your plane that was probably somewhere between 25-30 mph, 

a lot slower than the Ercoupes you used to fly.  The engine rpm is 

irrelevant if you've achieved flying speed; you could accelerate to flying 

speed, chop the power to idle, and pop the plane up into the air... though 

of course you won't stay up long.  The rpm necessary to accelerate to 

flying speed on the ground is considerably less than that needed to stay 

airborne, since there is much less drag when the wheels and not the wings 

are supporting the aircraft's weight.



Your engine trouble (rough idle and hesitation when the throttle is opened) 

sounds a rich mixture at idle.  However, all single and two cylinder 

2-strokes run rather rough at low rpm.

Hope your healing is going well.  Any thoughts on where you'll go from 

here, flying wise?



-Dana

--

  End rush hour traffic now! Legalize vehicular weaponry!

Ralph B

Joined: 14 Apr 2007
Posts: 367
Location: Mound Minnesota

Posted: Tue Aug 05, 2008 10:05 am Post subject: Re: safety experiment

williamtsullivan(at)att.n 	  Quote: 	
		  Richard Stracke's recent posting started me wondering how many people have had a similar experience with an unintentional lift-off in a Kolb.  I had attributed my accidental take-off to a gust, but Richard's use of the term "ballooning" seems to be a more appropriate term.  I had been taxiing for engine testing, going at what I thought was a moderate, controllable speed.  Probably about the same as one would use going down a taxi-way to the other end of a runway.  I had been having engine trouble, with several distinct problems.  At idle, there was a very heavy vibration- a shaking- that smoothed out above 2500 rpm.  When I taxied the length of the runway- 900 feet or so- , and then went back to idle, the engine would "load up" and not promptly respond to throttle advance for a few seconds.  Or, it would go the other way, and reduce rpms to 1400 or so, and nor respond at all until I shut it down and re-started.  At the  north end of the field, a couple of hundred feet from the end,  there was an area that was slightly down hill, and would cause the plane to noticeably accelerate, even at idle.  Sometimes I would have to shut off the motor to slow down enough to make my u-turn.  I am not sure, but I think this is where my event occurred.  My memory of all of it is still very shaky, more like a series of pictures than a flow of events.

    In order to help others stay away from a similar problem, I would like to enlist some help from the experienced members of the List.  How slowly can someone make a very light Firestar take off?  Or for that matter, what is the slowest lift-off speed of any of the Kolbs?  My Firestar lifted off with a gross weight of about 475 lbs. , and about 2700rpm.  What could be indicators of an imminent lift-off?  How can ground speed be determined prior to such an event?  Can a few of you take  your plane and, on a long, safe area, carefully induce the plane off the ground and report the speeds and conditions?  Maybe a GPS to determine it.

   

                                                  Thanks

                                                           

                                                        Bill Sullivan 

	




Bill, light Kolb aircraft lift off the ground quickly and the very light ones in a few feet with very little throttle. Mine is 319 lbs and stalls at 20 mph indicated. Since it's so light on the tail, I will go with full back stick and gradual full throttle. Once the plane is airborne, the stick goes forward or it will stall. This method isn't recommended for novices as they may not get the stick forward in time and end up stalling. This is my technique for crosswind takeoffs as the tail needs to be planted until it reaches flying speed or it will go off the runway. I would say the Firestar lifts off at 30 mph.



Ralph

_________________
Ralph B

Kolb Kolbra 912uls
N20386
550 hours

jbhart(at)onlyinternet.ne
Guest

Posted: Tue Aug 05, 2008 10:40 am Post subject: safety experiment

At 01:50 PM 8/5/08 -0400, you wrote:

 	  Quote: 	
		  



Bill,



However, all single and two cylinder 

2-strokes run rather rough at low rpm.



 
	


This may be a characteristic of a piston ported two cycle engine, but it is 

not true of a reed valve two cycle engine.



Jack B. Hart FF004

Winchester, IN

williamtsullivan(at)att.n
Guest

Posted: Tue Aug 05, 2008 10:45 am Post subject: safety experiment

So far, a fast walk is the best description of the safest speed to taxi.  My sppeds at 2700 rpm were about running speed.  I had had a one wing lift-off a couple of weeks earlier at about walking speed, caused by a strong gust coming in from my left.  I thought I had a flat tire, or bent a landing gear- I had bent a couple of soft quality replacements prior to this (see the List under Firestar project).  Another factor in generating lift-off speed might have been that the grass had been recently mowed.

    My only experience in observing ultralights taking off was watching Ed Harvey's Firefly, and Paul Gibney's Mitchell wing- but these were full power intentional take-offs.  They had both observed my taxiing method, and neither had thought it fast enough to mention any hazards.  I think the Firestar was deceptively large for it's weight, weighing in at about 307 with gas, and I only weighed 170 dressed.  I think  observers would think it would require a lot more speed to take off.

    The other known factor that day was weather.  Temp in the 70's, completely overcast with clouds at about 1400 feet, some minor wind- enough to spin the sock around and lift it half way, then drop it.  At lift-off it was overcast, but when I woke up looking at the EMT's face the sun was shining.  Figure about 20 minutes total for the sky to clear up. I can't give a wind speed in mph for that.

    When more people check in, maybe we can get some kind of formula regarding gross weight, wind speed, wing area, and safe taxi speeds.

   

                                                          Bill Sullivan

 [quote][b]

williamtsullivan(at)att.n
Guest

Posted: Tue Aug 05, 2008 11:42 am Post subject: safety experiment

Dana- I kow I wasn't going anywhere near 25 mph, but that doesn't count a stray gust.  Like I said, about running speed (I think).  Once it popped up, it went/rolled to the right- and there were marker cones, vent pipes for the old dump, and an embankment with a road.  I had been told that if I ever got in trouble down at that end, to immediately go to full throttle and get away from the ground.  Luckily, the engine didn't bog down, but that only delayed things for a few minutes. My vibration was a lot more than the other two 447's I'd seen; maybe motor mounts?

    Healing is progressing nicely.  Still in a wheelchair, but can walk around a bit before lying down or sitting.  The neck brace turned out to be totally unnecessary, as I had a lot of previous damage.  I see the doctor in another 5 weeks.

    I will probably try to rebuild the Firestar.  It will give me something to do this  winter.  My wife is continuing to take lessons up in Northampton, time and weather permitting.  She took her most recent lesson in a CT Sport.  She said it was a lot more sensitive than the Cessna.

    I can't do a full damage assessment on the Firestar until I can shift parts around.  What I did see tells me it can be fixed.  It wasn't ready to go in the air- The wings only had temporary hardware store multi-hole clevis pins in them!  We will see.

   

                                                   Bill Sullivan

 [quote][b]

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Tue Aug 05, 2008 2:46 pm Post subject: safety experiment

At 02:45 PM 8/5/2008, william sullivan wrote:

 	  Quote: 	
		     So far, a fast walk is the best description of the safest speed to 

 taxi.  My sppeds at 2700 rpm were about running speed.  I had had a one 

 wing lift-off a couple of weeks earlier at about walking speed, caused by 

 a strong gust coming in from my left...


	


Do you remember learning crosswind taxi technique, how to hold the ailerons 

depending on the wind direction?



If you're taxiing fast enough to get the tailwheel off the ground, it's too 

fast unless you're on the runway, and prepared to fly.



 	  Quote: 	
		  ... I think the Firestar was deceptively large for it's weight, weighing 

in at about 307 with gas, and I only weighed 170 dressed....

   When more people check in, maybe we can get some kind of formula 

 regarding gross weight, wind speed, wing area, and safe taxi speeds.


	


Well, you can use the stall speed calculations in AC103-7:  Based on a wing 

area of 140 ft², which I believe is correct for the Firestar, and an all up 

weight of 477 lbs, the 103-7 nomograph gives a stall speed of 25 

knots.  Subtract from that the max gust speed and a reasonable safety 

factor, and you have a max taxi speed.



 	  Quote: 	
		  It wasn't ready to go in the air- The wings only had temporary hardware 

store multi-hole clevis pins in them!


	


Yikes!  No WAY would I fast taxi any aircraft that wasn't ready to 

fly!  You're even luckier to be alive than I thought.



-Dana

--

  Politicians and diapers have one thing in common.  They should both be 

changed regularly, and for the same reason.

aoldman(at)xtra.co.nz
Guest

Posted: Tue Aug 05, 2008 5:34 pm Post subject: safety experiment

You engine problem has all the indications of being over rich. If you have 

the same problem again remove the air filter and try again. This will lean 

it out a bit. It maybe that all that is required is for the aircleaner to be 

cleaned. If it has been run at low RPM for some time the aircleaner may have 

a lot of oil in it.



 Regards

Tony

MK111

503

---

williamtsullivan(at)att.n
Guest

Posted: Tue Aug 05, 2008 6:00 pm Post subject: safety experiment

Tony- I have to table engine work until I put the plane back together, but I will save your notes.  Thank you.  The air cleaner was new, but did have a lot of low rpm running time- maybe 4 hours at or under 2700rpm.  The other engine problem I don't think I mentioned was that after I changed from a 10 gallon tank (very dirty) to a clean 5 gallon tank was a drop in max rpm from 6500 (10gal.) to 6200 (5 gal.).  I did keep trying to adjust the air and idle screws, but I don't recall the exact results.  I made many, many trips down the runway and back while trying to fix the loading up, or bogging down, problem I had.  Make a run, try it, shut down and adjust, and repeat.  I didn't have brakes, so I had to stand outside with a foot on the strut and rev it up to 4000 or so to clear it.  Then I'd get in, and repeat the taxi run to see if it would happen again.  It was during this testing I had my lift-off.

    

                                        Bill Sullivan

 [quote][b]

aoldman(at)xtra.co.nz
Guest

Posted: Tue Aug 05, 2008 10:43 pm Post subject: safety experiment

Good luck with the rebuild. I would suggest you tie  the Kolb down and sort the engine out when you get your other problems sorted.  With it tied down you can run the engine through its full RPM range. Its good to  hear your mishap has not put you off. Get your self well, then attend to the  Kolb . Good health and make your own good luck.

  

 Regards

             Tony    

 [quote]   ---

williamtsullivan(at)att.n
Guest

Posted: Wed Aug 06, 2008 12:58 am Post subject: safety experiment

Thanks, Tony.  I don't have to tie it down-  it's going to be a major rebuild. Sitting in a pile in the back yard right now.  When I am capable of walking, I will get pictures and post them.

   

                                               Bill Sullivan

  do not archive

   

 [quote][b]

aoldman(at)xtra.co.nz
Guest

Posted: Wed Aug 06, 2008 2:12 am Post subject: safety experiment

OKy , I might just go and take some flying photos  myself, for two reasons. One is I have been neglecting aviation a bit lately  and second to remind you of what you are  missing.  Half a world away I would like to think begining aviators  have the support of of us all. On this post there is a lot of very good advise  from some very experianced people . For our sport that can be a bit of  a problem. It may save some bent tubes and some lives but it does put a  hand brake on  inivation.

 Having said that we should individualy asses all the information available  and take the road that seems plausable to us.

 Dont expect to get it right every time. This flying thing is no harder than  driving a car {so my instructor informed me when I had a bit of a problem  working out where the ground was}

 Heal well

 Tony

 From: william sullivan (williamtsullivan(at)att.net) 

 [quote]   To: kolb list (kolb-list(at)matronics.com) 

   Sent: Wednesday, August 06, 2008 8:57    PM

   Subject: safety    experiment

   



     Thanks, Tony.  I don't have to tie it down-  it's going    to be a major rebuild. Sitting in a pile in the back yard right now.     When I am capable of walking, I will get pictures and post them.

    

                                                   Bill Sullivan

   do not archive

    

 	  Quote: 	
		  



href="http://www.matronics.com/Navigator?Kolb-List">http://www.matronics.com/Navigator?Kolb-List

href="http://forums.matronics.com">http://forums.matronics.com

href="http://www.matronics.com/contribution">http://www.matronics.com/c

	
[b]

rp3420(at)freescale.com
Guest

Posted: Wed Aug 06, 2008 8:13 am Post subject: safety experiment

Bill Sullivan,

  

 I publicly wanted to let you know how much I appreciate  your willingness to be so upfront about your misadventure.  The many things  that I have learned from your posts and everyone else's replies and advise on  this subject is truthfully a blessing to me personally.  I know in future  archives others will gain from this adventure, even to the point of saving  lives.

  

 Thanks you for your openness and honesty.  Thank  you for this list and the great ideas and advise.  This is what it's all  about.

  

 Tim Gherkins

 Phx-AZ

 FSII- Prepped to fly, getting  instruction.

  

  

   From: owner-kolb-list-server(at)matronics.com  [mailto:owner-kolb-list-server(at)matronics.com] On Behalf Of william  sullivan

Sent: Wednesday, August 06, 2008 1:57 AM

To: kolb  list

Subject: safety experiment

 

   Thanks, Tony.  I don't have to tie it down-  it's going to  be a major rebuild. Sitting in a pile in the back yard right now.  When I  am capable of walking, I will get pictures and post them.

  

                                               Bill Sullivan

  

[quote]



href="http://www.matronics.com/Navigator?Kolb-List">http://www.matronics.com/Navigator?Kolb-List

href="http://forums.matronics.com">http://forums.matronics.com

href="http://www.matronics.com/contribution">http://www.matronics.com/c

[b]

williamtsullivan(at)att.n
Guest

Posted: Wed Aug 06, 2008 4:09 pm Post subject: safety experiment

Mike- Your VG demo tape was very informative for my purposes.  The angle of attack at 30 mph was much greater than my Firestar was when parked.  With you weighing in at 1000 lbs., and me at 475, it tells all of us just how close to an unintentional lift-off even a slow taxi could be- and especially with no ground speed indication. 

   

                                             Bill Sullivan

 [quote][b]

R. Hankins

Joined: 18 Jan 2006
Posts: 185
Location: Grants Pass, Oregon

Posted: Mon Aug 11, 2008 10:16 am Post subject: Re: safety experiment

Bill,

I can't help but notice that you have mentioned ground speed several times in connection with your unintentional lift-off.  This line of thinking can get one in trouble.  It is airspeed and airspeed only that will lift you off of the ground.  I have landed in gusty winds and had a wing come up at no more than walking speed.  I have watched my firestar lift off a few inches for several seconds at a time while tied to the cables on the ramp at Lakeview, Oregon.  Zero ground speed, but flying!  A ground speed indicator is only valuable if you know the headwind component and consider the resulting airspeed.  The Wright Bro's. did a lot of high wind flying in 1902 with gliders tethered to the ground like kites; Zero ground speed, but flying.

Don't get too caught up in ground speed, think about how fast the air is traveling over the wings.



Just a thought,

_________________
Roger in Oregon
1992 KXP 503 - N1782C

williamtsullivan(at)att.n
Guest

Posted: Mon Aug 11, 2008 1:24 pm Post subject: safety experiment

Roger- You hit the nail on the head.  I was given to understand that the ASI would not work at lower air speeds (turns out mine didn't work at all), so the only frame of reference would be a comparable ground speed.  This would apply only in a low or no wind condition.  Would a Hall's ASI work for slow air speeds?

   

                                             Bill Sullivan

 [quote][b]

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Mon Aug 11, 2008 1:45 pm Post subject: safety experiment

At 05:23 PM 8/11/2008, william sullivan wrote:

 	  Quote: 	
		     Roger- You hit the nail on the head.  I was given to understand that 

 the ASI would not work at lower air speeds (turns out mine didn't work at 

 all), so the only frame of reference would be a comparable ground 

 speed.  This would apply only in a low or no wind condition.  Would a 

 Hall's ASI work for slow air speeds?


	


It depends on the ASI, you should have no trouble finding one that reads 

down to well below stall speed, which is all you really need.  Mine (a 

conventional round type) reads 20-80 mph, though the needle goes a bit 

below the 20 mark.  The Hall meters start at 7 mph, which means 10 mph is 

probably a reasonable minimum indication.



Groundspeed is MEANINGLESS.  Even if you know the surface wind speed, it'll 

be different even at 25' of altitude.  The only value of GPS speed is 

estimating arrival time on cross countries, or as a sanity check (not an 

accurate calibration!) of your ASI if the wind is steady.



-Dana

--

  The missionaries go forth to Christianize the savages-- as if the savages 

weren't dangerous enough already.

DAquaNut(at)aol.com
Guest

Posted: Mon Aug 11, 2008 8:21 pm Post subject: safety experiment

In a message dated 8/11/2008 4:24:50 P.M. Central Daylight Time,  williamtsullivan(at)att.net writes:

  	  Quote: 	
		     Would a Hall's ASI work for slow air speeds?

                                   

	
                                BILL

    I would trust the Halls over any other ASI.  They just  look a little out of place on a Kolb. I had one on my Firefly until I go a  Winter ASI. I had a UMA ASI  and it read about 20 mph off in spite of  trying all the tricks  J Hart had on His Web Site. The winter is expensive  but accurate!  I listened to John H. and I agree that Winter is the way to  go !

  

       Ed Diebel    FF#  62   (in Hou.).



Looking for a car that's sporty, fun and fits in your budget? Read reviews on AOL Autos.

  [quote][b]

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