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jdm(at)wideworld.net
Guest

Posted: Fri Mar 03, 2006 8:53 am Post subject: To cut or not to cut?

 	  Quote: 	
		   Jerb and all,

 The Original 5-rib wing Firestar had a gross weight limit of 535 lbs.




	




Does it state this on the plans?  My plane is 388 wet and I'm 215 on a good 

day.  That's 603.  Now add 25 for a BRS and I'm at 628. That's well over 

535.  I was starting to feel better about all this but I just got that sick 

feeling back in my stomach. Guess I better skip lunch today! I also need to 

put a picture of my plane on my refrigerator to deter me from opening it 

more than I should!



Will adding 25 extra pounds by adding a BRS justify adding the extra weight? 

Or will this be the straw that broke the camel's back? At least I will have 

a chute assuming of course all goes well with the deployment and subsequent 

landing.

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Fri Mar 03, 2006 9:26 am Post subject: Re: To cut or not to cut?

There is no need to go to 7 ribs to streingthen your wing.  Moving and adding ribs might get complicated      You can just:



1.  Replace the old ribs with new ones

2.  Add angle aluminum to the rib leading and trailing edges as Mr. Hauck Suggested.



This way you get a super strong wing with no redesign needed     My MK-III has the same rib streingthing I suggested here, if you would like to see how it is done I will send you some pictures.



The more I think about this the more I think you should streingthen that wing and here is why.   The wing has LOTS of hours on it, and as Mr. Hauck said fatigue adds up over time, you have no idea how close it is to its limit.   The plane has a history of aerobatics, only God knows how much and how often, but the wing has obviously seen more hard use than it was designed for.    You are also at a very heavy weight for the 5 rib Firestar, do you see all these factors starting to add up ?  It would bother me...



When the other Kolb Firestar wing finally failed, it was in straight and level flight, no abnormal loads were being placed on it at the time   .   I would not suggest that everyone rip thier wings apart, as its well proven that Kolb's are strong and will handle loads that are beyond thier design limits...   But your Firestar sounds like it has been down the same road as the Firestar that did finally fail     Your wing has held up to almost a thousand hours of heavy weights and aerobatics, it might be close to its limit.



Michael A. Bigelow

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

Kolb MK-III Xtra, 912-S

WillUribe(at)aol.com
Guest

Posted: Fri Mar 03, 2006 10:20 am Post subject: To cut or not to cut?

John,

Your 5-rib FireStar has already surpassed the designed limitation due to  the 

use of the 503 and now your thinking of adding more weight.  IMHO  you should 

be thinking of going back to the Kolb recommended engine for  your model 

FireStar.  That is if your FireStar has not already suffered  fatigue, cracks or 

warping.  If you really want or need the 503 then you  should go with the Kolb 

recommended 7-rib FireStar.  

 

I remember reading in the builders manual to be very careful not to leave  

any scratches on the wing spar when installing the ribs. Now people are  saying 

it is OK to drill new holes and not worry about the old ones  just cover them 

with a rivet.  I would think that is worse but then what do  I know.

 

Regards,

Will Uribe

El Paso, TX

FireStar II  N4GU

http://home.elp.rr.com/airplane/

 

 

In a message dated 3/3/2006 9:55:53 A.M. Mountain Standard Time,  

jdm(at)wideworld.net writes:






 	  Quote: 	
		    Jerb and all,

 The Original 5-rib wing Firestar had a gross weight  limit of 535 lbs.




	




Does it state this on the plans?  My  plane is 388 wet and I'm 215 on a good 

day.  That's 603.  Now  add 25 for a BRS and I'm at 628. That's well over 

535.  I was  starting to feel better about all this but I just got that sick 

feeling  back in my stomach. Guess I better skip lunch today! I also need to 

put a  picture of my plane on my refrigerator to deter me from opening it 

more  than I should!



Will adding 25 extra pounds by adding a BRS justify  adding the extra weight? 

Or will this be the straw that broke the camel's  back? At least I will have 

a chute assuming of course all goes well with  the deployment and subsequent  

landing.

Kirk Smith

Joined: 10 Jan 2006
Posts: 78
Location: SE Michigan

Posted: Fri Mar 03, 2006 10:37 am Post subject: To cut or not to cut?

My plane is 388 wet and I'm 215 on a good 

 	  Quote: 	
		   day.  That's 603.  Now add 25 for a BRS and I'm at 628. That's well 

over 
	


 	  Quote: 	
		   535. 


	


and you have an engine that is larger than the plane was designed for.

Do not archive

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Fri Mar 03, 2006 10:55 am Post subject: To cut or not to cut?

,

| Your 5-rib FireStar has already surpassed the designed limitation 

due to  the

| use of the 503 and now your thinking of adding more weight.



| Will Uribe



Will/Gang:



Without a doubt, your post is the most intelligent one I have read so 

far on this thread.



I remember getting ready to build my original FS.  Wanted to put a 447 

on it, but Homer would not sell me one with the kit.  I took the 377 

and traded it off to Gerry Olenik for a 447.  Just prior to losing my 

FS, Homer and I had talked about a 503 for it.  I had plans to 

circumnavigate the border of CONUS summer of 1990.  I had pretty well 

worn out the two 447's I kept to keep my FS going so I could make air 

shows and fly ins.  Not to say anything bad about two strokes and get 

that crap started again, but as much as I flew, back then, that is 

what it took to keep me somewhat operational at all times.  I kept a 

447 built on the bench to put in the FS when the need arised.  It 

always arose a day or two prior to planned departure.



I get the impression some of you think if somebody on the Kolb List 

says it is ok to go fly your airplane, then you should relax, go fly, 

enjoy, and never consider the circumstances until it comes that 

critical time we never want to experience.



I have heard some say, "All I did was hard pull ups on take off." 

That won't hurt my Kolb.  May not, but one can perform loop in an 

original FS pulling far less G's that the individual who likes to pull 

up hard and feel those G's.  In fact, it is easier to to a nice 

symetrical loop with half power than it is will full power.  That is 

because we suffer from the high mounted pusher configuration. 

Performing an inside loop with full power sort of nullifies a lot of 

that power trying to overcome the thrust line.



Another thing.  If you have never tried to replace a rib on a Kolb, 

then you are in for a rude awakening.  After the rivets are drilled 

out of the main spar gusset, you will find that deep scratches will 

occur as soon as you try to slide that bugger off the main spar.  Back 

in the old days before I learned how to stretch a main spar gusset, we 

had a hell of a time trying to get some of those ribs in place on the 

main spar tube.  Not to mention the many holes that will now be unused 

when the ribs are relocated.



I mentioned in a previous post that I would pull the fabric, reinforce 

all lateral bracing of the leading edge of the wing, which is a 

whopping .028" wall 1.5" tube.  Then I would reinforce top and bottom 

of all 5 main ribs with 3/4 and 1/2 in aluminum angle.  While I was in 

there, I would reinforce the bow tip at the 45 and 90 deg points with 

1/2" tubing tied together with aluminum web to keep the 1/2 tubes in 

column.  Then I would cover up the wing, paint it, and go fly without 

the contant nagging reminder that I might have a couple wings that are 

not as strong as they should be.



I can not tell anyone else how to build or how to fly.  I won't do 

that.  Sure, it is easy to tell someone else to go fly, have fun, your 

over loaded, over powered antique ultralight is fine and dandy, safe 

to fly.  Course you ain't sitting in the pilots seat either.



I loved my FS and hated to see it go.  However, I learned a hell of a 

lot from that little airplane, and even more from the accident.  I'd 

love to build another one if I had the kit and the time to build, fly, 

and enjoy.  If I did, I would build the wing as I decribed above.  All 

5 ribs worth.  If I changed my mind and built a 7 main rib wing, I 

would still use my mod to strengthen the ribs, bracing of the leading 

edge, and the bow tip.  Sure, the normal per plans built wing is fine 

if flown as intended.  Shucks, I would have a hard time lolly gagging 

around like an old school marm in the air in a fresh, strong, hauck 

modified original FS.  I am sure it would not take long to have that 

little sucker flying just like it did nearly 20 years ago. 



Take care,



john h

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

WillUribe(at)aol.com
Guest

Posted: Fri Mar 03, 2006 11:16 am Post subject: To cut or not to cut?

Michael, 

As I  recall the accident, the leading edge wing failure on an early  

FireStar happened when trying to recover from a hammer head stall.  There  were 

abnormal loads being placed on it at the time of failure. 

Regards,

Will Uribe

El  Paso, TX

FireStar II  N4GU

http://home.elp.rr.com/airplane/ 

--

flht99reh(at)netzero.net
Guest

Posted: Fri Mar 03, 2006 3:11 pm Post subject: To cut or not to cut?

John, I have both the KX drawing and the KHP drawing. I assume (fool that I

am) that the technique you used to slide the ribs without scratching is to

insert a thin piece of clean edged aluminum sheet the diameter approximate

of the spar, circumferentially (of course open at one end to wrap around the

spar). This then would be slid in very carefully from the opposite side of

the rib flange. Am I correct? I also noted spaced centered between the newly

located ribs a lower false rib (5 required). This really appears to be a

massive undertaking by anyone's standards. It would be one thing to do from

scratch (new wings), but wow what a project. I pray I never have to tear

into mine.



And John, if you have reason to come to Ohio at some point, you can play

with my 503 powered Fire star KXP.



Near overwhelmed Ralph in Ohio



--

WhiskeyVictor36(at)aol.co
Guest

Posted: Fri Mar 03, 2006 7:23 pm Post subject: To cut or not to cut?

In a message dated 3/3/2006 11:06:25 A.M. Eastern Standard Time,  

ul15rhb(at)juno.com writes:



The  Original 5-rib wing Firestar had a gross weight limit of 535  lbs.

 

Ralph/John Murr/All,

 

Speaking of the original 1985 design model FireStar with 5 ribs and a  Rotax 

377 engine.  I bought a kit from Homer on June 30, 1989 and have  the plans 

and builders manual.

 

I have never seen the gross weight stated in print on any of the  

documentation I have, but on page 50 of the builders manual I quote, "The VNE of  the 

FireStar in calm air is 75 MPH.  As the air gets turbulent, reduce your  speed 

accordingly.  This airplane has a light wing loading.  Stresses  go way up if it 

is fully loaded and the air gets rough".

 

I have replaced the 377 engine (at 425 hrs) with a 447, added the  1-1/8 inch 

gear legs, brakes, 3/4 canopy, baggage board behind the  seat and have a 

second chance chute above my head between the wings.   Instrumentation is ASI, 

EGT, CHT, RPM, compass and ALT.  Otherwise it  is stock with a 5 gal. fuel tank.  

Empty wt. (as an UL) is  somewhat fat at about 280 lbs.  With full fuel (5 

gal. X 6 lb.  p/gal.) of 30 lbs., plus my 140 lbs., my gross is at 450 lbs.  On 

occasion,  when I go on a long X-country, I carry 4 more gals. of fuel in two  

cans as baggage, adding another 24 lbs., for a gross of 474 lbs.  Probably  

more, as I didn't include weight for a small tool kit, tie down ropes, fuel  

transfer hose, camera, cell phone, wallet full of $$ and other pocket  items.

 

I am a very conservative flyer and do worry about overstressing the plane  in 

rough air, so I always slow down for a more comfortable ride for  me.

 

John M, you will have to make your own decision on what to do.   Modifying 

the wing as John H suggested will add strength, but it also  adds weight.  

Calculate your gross weight carefully.  Because of your  personal body weight, you 

might be better off with a two place Kolb.   By the way, I've been to 

Smoketown's breakfast fly-in several times in my  Kolb.  Weather permitting I will see 

you there this year.

 

Bill  Varnes

Original Kolb FireStar

Audubon NJ

Do Not  Archive

jdm(at)wideworld.net
Guest

Posted: Fri Mar 03, 2006 8:06 pm Post subject: To cut or not to cut?

My gross weight is 600.  I guess I'm just too fat for my fat plane! There is 

no way I can loose 65 pounds.  guess I need a bigger plane!



I'm sure the plane would be ok for someone around 172 pounds.  I could lose 

the starter and battery and save 25 pounds. That gets it down to 535.



Anybody out there interested in a Firestar?  If you look on Frapper you can 

see its picture.  I live in south central PA and fly out of S37.  I also 

have an enclosed trailer on Barnstormers.com that it fits in.  I just got a 

hanger so I'm selling the trailer. I can sell it as a package deal? There is 

nothing wrong with the plane that I know of.  I just need a bigger plane to 

haul me around safer!



John Murr

WillUribe(at)aol.com
Guest

Posted: Fri Mar 03, 2006 9:02 pm Post subject: To cut or not to cut?

He John,

 

Your FireStar sure does have a nice paint job.

 

http://tinyurl.com/egchl

 

Regards,

Will Uribe

El  Paso, TX

FireStar II   N4GU

http://home.elp.rr.com/airplane/

 

do not archive



 

 

--

Kirk Smith

Joined: 10 Jan 2006
Posts: 78
Location: SE Michigan

Posted: Sat Mar 04, 2006 5:03 am Post subject: Re: To cut or not to cut?

The Kolb Firestar has been in production since 1985. In 1990 some styling changes were introduced resulting in the KX series.  The KXP is the KX with a stronger wing to accommodate the more powerful Rotax 503. The KXP has 7 ribs per wing vs 5 for the KX and original firestar, as mentioned previously. What I have not seen mentioned on this topic is that the KXP also has a stronger drag strut arrangement than the KX.  



Do not archive

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Eugene Zimmerman

Joined: 10 Jan 2006
Posts: 392

Posted: Sat Mar 04, 2006 5:47 am Post subject: To cut or not to cut?

On Mar 3, 2006, at 11:04 PM, John Murr wrote:



 	  Quote: 	
		   Anybody out there interested in a Firestar?


	




     Hi John,



By now you know that what you actually have there is a wolf in  

sheep's clothing.

How much do you want for that  dangerous  over-stressed Kolb death  

trap?   $3500.00?



Only joking of course!



You have a perfectly good plane.

I've seen it fly numerous times by it's former owner and I think you  

are being influenced to part with a jewel.

I've flown a five rib Firestar with much higher gross weights than  

yours for many years.

Fly with common sense and slowdown in rowdy  air and you and your  

plane will be fine.



If you do  decide to sell that show quality beauty, it is worth a  

premium.



Gene Zimmerman

planecrazzzy
Guest

Posted: Sat Mar 04, 2006 6:25 am Post subject: Re: To cut or not to cut?

Hi,

    I was looking over your plane ( Nice Job ) but I saw something kind of disturbing ( to me )  it looks like you have your Pitot tube on the Left "lift Strut".....What "I" thought was scary ...it looks like two holes were drilled into it to run the tubing on the inside....  I hope looking at those holes is on your preflight checklist...



                              Gotta Fly...

                                              Mike in MN



PS  What SIZE are the tires you have ....I'll probly get something like those when I change mine...( cost ? )

Richard Pike

Joined: 09 Jan 2006
Posts: 1671
Location: Blountville, Tennessee

Posted: Sat Mar 04, 2006 7:19 am Post subject: To cut or not to cut?

Maybe I'm missing something here (always a good chance of that) but 

isn't gross weight also a function of maximum G loading at a given 

stress factor?



Let's assume (and this is strictly an assumption) that Homer designed 

the Firestar for a +4.4 G load at 535 pounds, (which would be reasonable 

under Part 103) but now you have added weight, your Firestar weighs 628 

pounds at takeoff. Then in order to fly safely, you must reduce the 

maneuvering speed (and maximum speed) accordingly so that your new 

weight at any speed will not cause any higher G loading in any situation 

than the designer originally planned for.



For a detailed explanation, check out this page here

http://www.ushga.org/article08.asp



To keep it super-simple, if your airplane stalls at  (let's say) 35, and 

you get caught in turbulence, as long as you keep your airspeed below 

45, it is almost impossible to pull even 2 G's, because the wing will 

stall first.  Think about some of the turbulence you have flown in - if 

you fly at your normal cruising speed and hit a booming thermal or a 

rotor along a ridge top, you feel an appreciable and usually abrupt G load.

But if you slow that puppy down 15 - 20 mph and hit that same 

turbulence, the airplane just sort of wallows around, and although it 

feels sloppy, - and probably is, - it is obviously not being worked over 

or abused by the vulgar air. At 15 mph over stall speed, we are almost 

fool proof in the situations we normally fly our little airplanes in. 

(Not that some fool can't figure out how to exceed the limits...)

But in practical terms, that is the difference between bending the 

airplane or not.



At 628 pounds with a BRS, I would not be afraid to fly it, - but I would 

do the math, come up with some conservative and realistic V numbers, 

(calibrate your airspeed indicator accurately) not hot dog or play Mr. 

high-speed-flyby-pull-up, avoid flying in serious turbulence, (and slow 

down to an appropriate Va speed when it showed up unexpectedly) and then 

enjoy the airplane.



Richard Pike

MKIII N420P (420ldPoops)

John Murr wrote:

 	  Quote: 	
		   



 My gross weight is 600.  I guess I'm just too fat for my fat plane! There is 

 no way I can loose 65 pounds.  guess I need a bigger plane!



 I'm sure the plane would be ok for someone around 172 pounds.  I could lose 

 the starter and battery and save 25 pounds. That gets it down to 535.

 <snip>

 John Murr

_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.

rsanoa

Joined: 10 Jan 2006
Posts: 71
Location: Bell Buckle,TN

Posted: Sat Mar 04, 2006 7:56 am Post subject: To cut or not to cut?

I believe Richard is correct. If this old brain is in gear, I believe I was told that as your gross weight goes up, so does your stall speed and you can't normally damage anything when the wing stalls, whether it's 25 mph or 50 mph. As Richard so clearly points out, set a maneuvering speed and stay with it in rough air. I know I'm repeating what Richard said but his analysis is important for all of us to remember.  Of course the joker in the deck is the fact that many will "fly hard" regardless.

  do not archive



Richard Pike <richard(at)bcchapel.org> wrote:

  



Maybe I'm missing something here (always a good chance of that) but 

isn't gross weight also a function of maximum G loading at a given 

stress factor?



Let's assume (and this is strictly an assumption) that Homer designed 

the Firestar for a +4.4 G load at 535 pounds, (which would be reasonable 

under Part 103) but now you have added weight, your Firestar weighs 628 

pounds at takeoff. Then in order to fly safely, you must reduce the 

maneuvering speed (and maximum speed) accordingly so that your new 

weight at any speed will not cause any higher G loading in any situation 

than the designer originally planned for.



For a detailed explanation, check out this page here

http://www.ushga.org/article08.asp



To keep it super-simple, if your airplane stalls at (let's say) 35, and 

you get caught in turbulence, as long as you keep your airspeed below 

45, it is almost impossible to pull even 2 G's, because the wing will 

stall first. Think about some of the turbulence you have flown in - if 

you fly at your normal cruising speed and hit a booming thermal or a 

rotor along a ridge top, you feel an appreciable and usually abrupt G load.

But if you slow that puppy down 15 - 20 mph and hit that same 

turbulence, the airplane just sort of wallows around, and although it 

feels sloppy, - and probably is, - it is obviously not being worked over 

or abused by the vulgar air. At 15 mph over stall speed, we are almost 

fool proof in the situations we normally fly our little airplanes in. 

(Not that some fool can't figure out how to exceed the limits...)

But in practical terms, that is the difference between bending the 

airplane or not.



At 628 pounds with a BRS, I would not be afraid to fly it, - but I would 

do the math, come up with some conservative and realistic V numbers, 

(calibrate your airspeed indicator accurately) not hot dog or play Mr. 

high-speed-flyby-pull-up, avoid flying in serious turbulence, (and slow 

down to an appropriate Va speed when it showed up unexpectedly) and then 

enjoy the airplane.



Richard Pike

MKIII N420P (420ldPoops)

John Murr wrote:

 	  Quote: 	
		   



 My gross weight is 600. I guess I'm just too fat for my fat plane! There is 

 no way I can loose 65 pounds. guess I need a bigger plane!



 I'm sure the plane would be ok for someone around 172 pounds. I could lose 

 the starter and battery and save 25 pounds. That gets it down to 535.

 

 John Murr



 


	








		

---------------------------------

 Use Photomail to share photos without annoying attachments.

_________________
Ray S.Anderson

jdm(at)wideworld.net
Guest

Posted: Sat Mar 04, 2006 8:39 am Post subject: To cut or not to cut?

Ok so using the equation my stall speed (IAS) is 35 at 4.47 g's that puts Va 

at 74 and Vne at 85.  That sounds about right.  If I slow down to 50 my max 

g load could only be 2.04.



I didn't see gross weight in the equation, but I assume it is a factor of 

stall speed.  The higher the gross weight, the higher the stall speed.

Conclusion:  If I fly no faster than 74 in smooth air and no faster than 50 

in all other types of air. I should be fine.



Also I looked and the 503 DCDI is only 13 pounds heavier than the 447, so 

having a 503 shouldn't make a difference to the loading on the wing as long 

as I stay in the Va parameters above.  It's nice to have the 503 for short 

fields.  I climb out at about 60 until 800 AGL then throttle back.  I could 

climb a little steeper to get it down to 50.



---

Kirk Smith

Joined: 10 Jan 2006
Posts: 78
Location: SE Michigan

Posted: Sat Mar 04, 2006 9:20 am Post subject: To cut or not to cut?

 	  Quote: 	
		   Ok so using the equation my stall speed (IAS) is 35 at 4.47 g's that puts

Va
	


 	  Quote: 	
		   at 74 and Vne at 85.  That sounds about right.  If I slow down to 50 my

max
	


 	  Quote: 	
		   g load could only be 2.04.



 I didn't see gross weight in the equation, but I assume it is a factor of

 stall speed.  The higher the gross weight, the higher the stall speed.


	


35 at what weight?  What is the stall speed at 625lbs? I bet it's closer to

50.



Do not archive

jdm(at)wideworld.net
Guest

Posted: Sat Mar 04, 2006 9:34 am Post subject: To cut or not to cut?

At current gross weight of 603 it is 35 IAS. (tested at altitude using GPS 

and it is real close)



---

Kirk Smith

Joined: 10 Jan 2006
Posts: 78
Location: SE Michigan

Posted: Sat Mar 04, 2006 10:01 am Post subject: Re: To cut or not to cut?

At current gross weight of 603 it is 35 IAS. (tested at altitude using GPS 

and it is real close) 

That's good.    Another suggestion you might consider, is cutting inspection holes in the wing fabric to look it over inside.  



Do not archive

jdm(at)wideworld.net
Guest

Posted: Sat Mar 04, 2006 10:17 am Post subject: To cut or not to cut?

I do have inspection holes but it's very hard to see very small hair-line 

cracks.



Another thing I could do is have someone on this list about my weight do a 

few loops, hammerheads, and fly it around at 100 mph mid-day in the summer 

and see what happens? Volunteers should bring their own cute.  I don't want 

to pay the repacking fee on mine!



---

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