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FireFly Weight and Balance

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sidsx

Joined: 16 Aug 2019
Posts: 5

Posted: Sat Aug 24, 2019 10:03 am Post subject: FireFly Weight and Balance

Can anyone tell me if the CG limits for the FireFly are different from the FireStar

(12.8 to 22.4} I have a copy of the W&B for the FireStar not for the FireFly.

Thanks,

byoungplumbing(at)gmail.c
Guest

Posted: Sat Aug 24, 2019 10:48 am Post subject: FireFly Weight and Balance

 	  Quote: 	
		  

 

 Can anyone tell me if the CG limits for the FireFly are different from the FireStar

	




I think the Firefly and firestar have different size air frames and possibly airfoils .Â  so to run the calculations for CG for and aft in inches,Â  Â comparing one to the other, I think would not be wise.. I think if you calculated the inches to percent of wing cord onÂ  the firestar,Â  Â then using the same percent of wing cord on the Firefly

.Â  Calculate back to get the inches... I think you would be more accurate.

And on the other hand someone may have the plans and numbers of the Firefly and make it easy!

Boyd Young

Mkiii Utah

 	  Quote:

sidsx

Joined: 16 Aug 2019
Posts: 5

Posted: Sat Aug 24, 2019 10:55 am Post subject: Re: FireFly Weight and Balance

Thank you for the reply. I'll do what you suggest if no one with a FireFly post the exact numbers. It would be much easier with them.

capedavis(at)yahoo.com
Guest

Posted: Sat Aug 24, 2019 11:04 am Post subject: FireFly Weight and Balance

Hi I recommend u call KOLB Iâ€™m sure they know the answer.   Chris



Sent from my iPhone



 	  Quote: 	
		   On Aug 24, 2019, at 2:03 PM, sidsx <sidsx66(at)gmail.com> wrote:

 

 

 

 Can anyone tell me if the CG limits for the FireFly are different from the FireStar

 (12.8 to 22.4} I have a copy of the W&B for the FireStar not for the FireFly.

 Thanks,

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=491026#491026

sidsx

Joined: 16 Aug 2019
Posts: 5

Posted: Sat Aug 24, 2019 11:06 am Post subject: Re: FireFly Weight and Balance

I tried that. Never received a reply from them.

jhauck36(at)outlook.com
Guest

Posted: Sat Aug 24, 2019 12:20 pm Post subject: FireFly Weight and Balance

Keep calling Kolb until someone answers the phone, usually Bryan Milburn.



john h

mkIII

Titus, Alabama





--

stuart(at)harnerfarm.net
Guest

Posted: Sat Aug 24, 2019 2:01 pm Post subject: FireFly Weight and Balance

Here is a scan of the W&B instructions from my 2013 Firefly



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sidsx

Joined: 16 Aug 2019
Posts: 5

Posted: Sat Aug 24, 2019 2:29 pm Post subject: Re: FireFly Weight and Balance

Thank you so much!!!

Eugene Zimmerman

Joined: 10 Jan 2006
Posts: 392

Posted: Sun Aug 25, 2019 8:59 am Post subject: Re: FireFly Weight and Balance

Concern about CG limits on any Kolb aircraft is for all practical purposes unnecessary unless there is a significant deviation from, or modification of, the airframe from the original Kolb design plans.



The best way to optimize the CG on any Kolb airplane is to test fly the airplane and trim the control surfaces to fly hands off straight and level.  Modifying a Kolb aircraft's CG is beneficial only for the purposes of minimizing significant control surface deflection necessary for neutral-hands off straight and level flight.

jhauck36(at)outlook.com
Guest

Posted: Sun Aug 25, 2019 9:57 am Post subject: FireFly Weight and Balance

I agree with Gene Zimmerman.  I've built 3 Kolbs, US, FS, and MKIII.  Never did a weight and balance on the US and FS.  Test flew it, added a trim tab to aileron, elevator, and rudder.  Trimmed and test flew for best cruise flight.



My MKIII has aft CG on paper.  Flies neutral with no pitch trim at glide, idle rpm.  Bring up the power and it takes a lot of nose up pitch trim to fly neutral.  That doesn't sound like aft cg.



Pushers with high thrust line like the FS and MKIII have significant pitch change from idle to cruise power or full power.  Lots of Kolbers don't recognize this, thinking something is wrong with their airplanes.



Build it according to plans and it will be within cg limits.



I have made significant modifications to all my Kolbs and never experienced a cg problem, never had to add 40 lbs of lead to the nose cone, etc.



john h

mkIII

Titus, Alabama





--

racerjerry

Joined: 15 Dec 2009
Posts: 202
Location: Deer Park, NY

Posted: Tue Aug 27, 2019 4:24 am Post subject: Re: FireFly Weight and Balance

I cannot argue with John H's success in Kolb airplanes.  I do argue that while Homer's designs have proven themselves to be quite stable and forgiving, promoting the idea that weight and balance calculations are not needed might be carried over to other aircraft where the results could be deadly.



I make two sets of W&B calculations at worst conditions of both forward and aft loading.



In Kolbs, it really helps to have someone else read the scales while pilot is seated in the airplane  )



I bought 4 (1 spare) new very flat bathroom scales for $10 each many moons ago that worked perfectly for the job.  You do need to take care not to side-load the scales for accurate readings.   Climbing into the pilot seat while aircraft is on scales will spread the main wheels slightly and cause a scale side-loading error.  The cure for side loading is greased plates on top of one main wheel scale.  Un-greased plates on opposite side keeps things level.  Cheap 12 x 12 floor tiles work fine for this purpose.



BTW, if you are flying a Cessna Cardinal (rearward wing) with constant speed prop; two heavyweights in winter clothing up front with no other passengers or baggage, you could get yourself in trouble.  There is a reason why Cessna added slots to the stabilator on early Cardinals and many pilots found out the hard way during flare.



Jerry King

_________________
Jerry King

rickofudall

Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA

Posted: Wed Aug 28, 2019 6:33 am Post subject: FireFly Weight and Balance

Sid, Measure the chord of the FIrefly wing, include the aileron. Divide by 4. That's the quarter chord point measured from the leading edge. That is roughly the ideal CG. Divide your original chord measurement by 10. Add and subtract that number from the quarter chord point. That's your CG range from 15% to 35% chord. If you find your CG is a little aft, BUT by no means further than 40% chord, you're still OK, Kolbs tend to fly better with an aft CG. However, if you can move something forward to get into the 15 to 35% range, do that.Last, It is vitally important that you get the aircraft at the proper attitude for measuring the arms. Roughly, it's horizontal stabilizer level. Check with Kolb they may have an angle for the engine mount (about 3 degrees for the Mk III) or the underside of the wing (9 degrees on the Mk III).Â Â 

I know that the Kolb uses the the leading edge of the wing as the origin for calculating the CG. Do yourself a favor and use the nose of the aircraft instead. The reason is simple, no negative numbers in your calculations. If you keep the origin forward all calculations are additions (you could put the origin at the tail for that matter and all calculations would still be consistent and that's what you're after).Â  Nothing can screw up a CG calculation faster than adding a moment arm when it should be subtracted.

Hope this helps,

Rick

On Sat, Aug 24, 2019 at 1:06 PM sidsx <sidsx66(at)gmail.com (sidsx66(at)gmail.com)> wrote:



 	  Quote: 	
		  --> Kolb-List message posted by: "sidsx" <sidsx66(at)gmail.com (sidsx66(at)gmail.com)>

 

 Can anyone tell me if the CG limits for the FireFly are different from the FireStar

 (12.8 to 22.4} I have a copy of the W&B for the FireStar not for the FireFly.

 Thanks,

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=491026#491026

 

 

 

 

 

 

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â€œBlessed are the cracked, for they shall let in the light.â€ Â Â Groucho Marx

_________________
The smallest miracle right in front of you is enough to make you happy....

rickofudall

Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA

Posted: Wed Aug 28, 2019 6:47 am Post subject: FireFly Weight and Balance

Eugene, That's about the worst advice I've ever seen on this forum.Â First, if the aircraft has any sort of experimental certificate, either ELSA or EAB, a weight and balance measurement is REQUIRED by law. It's a part of your aircraft's operating limitations.

Second, Aft CG has probably been the cause or contributed to far too many stall spin accidents, or as the FAA calls it, Loss of Control.

Just because it's an ultralight doesn't give the aircraft a pass on the physics of flight. Assuming an aircraft is in proper trim is like assuming the pistol is unloaded.

There is one positive side to not doing a W & B, you'll probably qualify for next year's Darwin Awards.

Rick

On Sun, Aug 25, 2019 at 12:01 PM Eugene Zimmerman <etzimm(at)gmail.com (etzimm(at)gmail.com)> wrote:



 	  Quote: 	
		  --> Kolb-List message posted by: "Eugene Zimmerman" <etzimm(at)gmail.com (etzimm(at)gmail.com)>

 

 Concern about CG limits on any Kolb aircraft is for all practical purposes unnecessary unless there is a significant deviation from, or modification of, the airframe from the original Kolb design plans.

 

 The best way to optimize the CG on any Kolb airplane is to test fly the airplane and trim the control surfaces to fly hands off straight and level.Â  Modifying a Kolb aircraft's CG is beneficial only for the purposes of minimizing significant control surface deflection necessary for neutral-hands off straight and level flight.

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=491047#491047

 

 

 

 

 

 

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â€œBlessed are the cracked, for they shall let in the light.â€ Â Â Groucho Marx

_________________
The smallest miracle right in front of you is enough to make you happy....

baberdk

Joined: 23 Jan 2014
Posts: 53
Location: East Moline, Il

Posted: Wed Aug 28, 2019 8:01 am Post subject: FireFly Weight and Balance

I agree with your observations on weight and balance. If you can get the center of gravity right below the center of lift you won't need any trim tabs. I also like to calculate it with an empty tank of gas so if that ever happens you can still fly it to the ground.Â 



Respectfully,

Dennis Baber

Cape Coral, Fl

baberdk(at)gmail.com (baberdk(at)gmail.com)





Stay CuriousÂ

jhauck36(at)outlook.com
Guest

Posted: Wed Aug 28, 2019 8:49 am Post subject: FireFly Weight and Balance

I disagree on your statement:  "If you can get the center of gravity right below the center of lift you won't need any trim tabs."   

  

In one respect it is probably true.  That being flying the Kolb without power.  However, as soon as you bring the power in, the high thrust line will push the  nose down and aft stick pressure will be required to hole the aircraft level, unless you have forced pitch trim or an elevator trim tab.  It is the nature of the beast. 

  

I recently related my experience with my MKIII.  No pitch trim, no power, perfect hands off flight.  Bring in the power and bring in the nose up forced trim. 

  

john h 

mkIII 

Titus, Alabama 

   

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

 Sent: Wednesday, August 28, 2019 11:00 AM

 To: kolb-list(at)matronics.com

 Subject: Re: Kolb-List: FireFly Weight and Balance 

 

   

I agree with your observations on weight and balance. If you can get the center of gravity right below the center of lift you won't need any trim tabs. I also like to calculate it with an empty tank of gas so if that ever happens you can  still fly it to the ground.                                                                         

  

  

  

  

Respectfully,

 Dennis Baber 

  

Cape Coral, Fl 

  

baberdk(at)gmail.com (baberdk(at)gmail.com) 

  

  

  

  

Stay Curious

tkrolfe(at)toast.net
Guest

Posted: Wed Aug 28, 2019 2:17 pm Post subject: FireFly Weight and Balance

Rick,     

Who died and made you God?!Â  This is why some of us went to       ultralights so that we could get away from aviation Nazi's like       you.Â  You think you know it all, but have no idea how much time       Eugene has in the air proving you wrong.Â  I think he knows more       about the physics of flight then you will ever understand.Â  

          

Maybe you could suggest you disagree without be an a-hole about       it.Â  Talk about a an entry into the Darwin awards.Â  Grow up!!     

Terry     



          On 8/28/2019 10:46 AM, Richard Girard       wrote:

     

      	  Quote: 	
		                         Eugene, That's about the worst advice I've ever           seen on this forum.Â            First, if the aircraft has any sort of experimental             certificate, either ELSA or EAB, a weight and balance             measurement is REQUIRED by law. It's a part of your             aircraft's operating limitations.

           Second, Aft CG has probably been the cause or contributed             to far too many stall spin accidents, or as the FAA calls             it, Loss of Control.

           Just because it's an ultralight doesn't give the aircraft             a pass on the physics of flight. Assuming an aircraft is in             proper trim is like assuming the pistol is unloaded.

           There is one positive side to not doing a W & B,             you'll probably qualify for next year's Darwin Awards.

           

           

           Rick

         

         

                    On Sun, Aug 25, 2019 at             12:01 PM Eugene Zimmerman <etzimm(at)gmail.com (etzimm(at)gmail.com)>             wrote:

           

            	  Quote: 	
		  --> Kolb-List message             posted by: "Eugene Zimmerman" <etzimm(at)gmail.com (etzimm(at)gmail.com)>

             

             Concern about CG limits on any Kolb aircraft is for all             practical purposes unnecessary unless there is a significant             deviation from, or modification of, the airframe from the             original Kolb design plans.

             

             The best way to optimize the CG on any Kolb airplane is to             test fly the airplane and trim the control surfaces to fly             hands off straight and level.Â  Modifying a Kolb aircraft's             CG is beneficial only for the purposes of minimizing             significant control surface deflection necessary for             neutral-hands off straight and level flight.

             

             

             

             

             Read this topic online here:

             

             http://forums.matronics.com/viewtopic.php?p=491047#491047

             

             

             

             

             

             

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                                                                                    â€œBlessed are                     the cracked, for they shall let in the light.â€ Â Â Groucho                       Marx

russk50(at)gmail.com
Guest

Posted: Wed Aug 28, 2019 5:44 pm Post subject: FireFly Weight and Balance

Terry: Grow Up! 	  Quote: 	
		  On Aug 28, 2019, at 6:15 PM, Terry <tkrolfe(at)toast.net (tkrolfe(at)toast.net)> wrote:

              

Rick,

Who died and made you God?!  This is why some of us went to       ultralights so that we could get away from aviation Nazi's like       you.  You think you know it all, but have no idea how much time       Eugene has in the air proving you wrong.  I think he knows more       about the physics of flight then you will ever understand.       

Maybe you could suggest you disagree without be an a-hole about       it.  Talk about a an entry into the Darwin awards.  Grow up!!

Terry

          On 8/28/2019 10:46 AM, Richard Girard       wrote:     

      	  Quote: 	
		                         Eugene, That's about the worst advice I've ever           seen on this forum.            First, if the aircraft has any sort of experimental             certificate, either ELSA or EAB, a weight and balance             measurement is REQUIRED by law. It's a part of your             aircraft's operating limitations.

           Second, Aft CG has probably been the cause or contributed             to far too many stall spin accidents, or as the FAA calls             it, Loss of Control.

           Just because it's an ultralight doesn't give the aircraft             a pass on the physics of flight. Assuming an aircraft is in             proper trim is like assuming the pistol is unloaded.

           There is one positive side to not doing a W & B,             you'll probably qualify for next year's Darwin Awards.

                      

           Rick

         

                             On Sun, Aug 25, 2019 at             12:01 PM Eugene Zimmerman <etzimm(at)gmail.com (etzimm(at)gmail.com)>             wrote:           

            	  Quote: 	
		  --> Kolb-List message             posted by: "Eugene Zimmerman" <etzimm(at)gmail.com (etzimm(at)gmail.com)>                          Concern about CG limits on any Kolb aircraft is for all             practical purposes unnecessary unless there is a significant             deviation from, or modification of, the airframe from the             original Kolb design plans.                          The best way to optimize the CG on any Kolb airplane is to             test fly the airplane and trim the control surfaces to fly             hands off straight and level.  Modifying a Kolb aircraft's             CG is beneficial only for the purposes of minimizing             significant control surface deflection necessary for             neutral-hands off straight and level flight.                                                                 Read this topic online here:                          http://forums.matronics.com/viewtopic.php?p=491047#491047                                                                                           ===========             -List" rel="noreferrer"             target="_blank">http://www.matronics.com/Navigator?Kolb-List             ===========             FORUMS -             eferrer" target="_blank">http://forums.matronics.com             ===========             WIKI -             errer" target="_blank">http://wiki.matronics.com             ===========             b Site -                       -Matt Dralle, List Admin.             rel="noreferrer"             target="_blank">http://www.matronics.com/contribution             ===========                                                  	
         

                           

         --                                                                                     â€œBlessed are                     the cracked, for they shall let in the light.â€   Groucho                       Marx

sidsx

Joined: 16 Aug 2019
Posts: 5

Posted: Wed Aug 28, 2019 10:50 pm Post subject: Re: FireFly Weight and Balance

I would like to thank everyone for their input, I find this forum to be very helpful.

Rex Rodebush

Joined: 10 Jan 2006
Posts: 209
Location: Branson West area, Missouri

Posted: Thu Aug 29, 2019 6:00 am Post subject: Re: FireFly Weight and Balance

Since "tkrolfe(at)toast.net" is a guest I can not respond to him directly so I'll do it this way.  Rick's comments on weight and balance were completely correct.  This is required by the FAA.  To suggest that you not bother to do one is very foolish. Your were completely out of line.  If you can not respond to comments in a civil manor I suggest you be a guest on another forum.

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