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Gross weight VS DA

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WurlyBird

Joined: 16 May 2008
Posts: 207
Location: North Pole, Alaska

Posted: Sun Jun 21, 2009 7:30 pm Post subject: Gross weight VS DA

I am not sure if I just got spoiled learning to fly my KF3 during winter/spring and then taking a little break or what but here is what I am wondering.  The KF would climb pretty good, about 500+ fpm with 360 pounds of pilots and about 10 gallons when it was cool out, 50-65 F on the ground.  I fly out of a field that is almost always between 500 and 800 feet PA and usually fly 500-1500 agl.  I was down for a while and went flying this weekend when it was about 85 F and the thing climbed, with the same pilot load and about half the fuel, like a fat anemic pig.  I barely got 300 fpm and it felt like it wanted to fall down rather then climb.  How much does DA cripple this plane?  What kind of DA do you fly at where you still feel like you have good climb authority?  



I actually climbed up to 5000 msl and everything handled like I was more accustomed to although it still didn't climb like the home-sick angel I am used to.  



What is "normal" as you go through the seasons with this plane?

_________________
James
Kitfox 3 / 582 / 70" IVO 2 blade GA
50 hrs on the 582 swapping for HKS 700E and Avid Cowl.

Guy Buchanan

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

Posted: Sun Jun 21, 2009 9:09 pm Post subject: Gross weight VS DA

At 08:30 PM 6/21/2009, you wrote:

 	  Quote: 	
		  I barely got 300 fpm and it felt like it wanted to fall down rather 

then climb.  How much does DA cripple this plane?  What kind of DA 

do you fly at where you still feel like you have good climb authority?


	


James,

         I had a good laugh with your post. Try laying off for a 

while, then loading to gross to go on a long cross country. I 

actually put mine back down once because I was CERTAIN I wasn't 

getting full power. Well, I wasn't. (DA + weight =, you know.) After 

some reflection and some ground runs I realized I was getting all I 

could expect and took off "like a fat anemic pig".

         One caveat, however. You have a 582, like I do. I have 

noticed that when the DA is up, if I lean before launch I can 

sometimes dramatically improve my performance. (I've got HACman.) 

Check your EGT's on launch. Make sure they're over 1000F. You may 

have to do some re-jetting.

Guy Buchanan

San Diego, CA

K-IV 1200 / 582-C / Warp / 300 hrs. and counting

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

Tom Jones

Joined: 12 Mar 2006
Posts: 752
Location: Ellensburg, WA

Posted: Mon Jun 22, 2009 4:52 am Post subject: Re: Gross weight VS DA

I'm glad to hear the 582's are affected by DA too.  My Kitfox with 503 is very sensitive to DA and weight.



James, Some 582 drivers repitch the prop and/or rejet the carbs with the seasons, summer and winter.

_________________
Tom Jones
Classic IV
503 Rotax, 72 inch Two blade Warp
Ellensburg, WA

WurlyBird

Joined: 16 May 2008
Posts: 207
Location: North Pole, Alaska

Posted: Tue Jun 23, 2009 7:15 pm Post subject: Re: Gross weight VS DA

As far as re-pitching, I have a GSC that I don't feel like messing with and plan on replacing it with a GA IVO soon.  I should probably adjust the jets since I am running a little cold but I have left that alone since I am currently battling a water temp issue which has me thinking I need to purchase the radiator scoop.  On that, any one replace the stock radiator with one a little larger?  What was the radiator meant for?  I tried shopping for a slightly larger radiator but all anyone cares about is what vehicle it is for and no one talks dimensions.



And just because I can't keep anything simple, all of this is taking place while I am trying to re-fly my 3 hours of test prep for my check ride.  The fun continues . . .

_________________
James
Kitfox 3 / 582 / 70" IVO 2 blade GA
50 hrs on the 582 swapping for HKS 700E and Avid Cowl.

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Wed Jun 24, 2009 2:03 am Post subject: Re: Gross weight VS DA

 	  WurlyBird wrote: 	
		  As far as re-pitching, I have a GSC that I don't feel like messing with and plan on replacing it with a GA IVO soon.  I should probably adjust the jets since I am running a little cold but I have left that alone since I am currently battling a water temp issue which has me thinking I need to purchase the radiator scoop.  On that, any one replace the stock radiator with one a little larger?  What was the radiator meant for?  I tried shopping for a slightly larger radiator but all anyone cares about is what vehicle it is for and no one talks dimensions.



And just because I can't keep anything simple, all of this is taking place while I am trying to re-fly my 3 hours of test prep for my check ride.  The fun continues . . . 	




What Rpm are you getting static and wide open in levle flight ?  MAybe you are too course and lugging engine. I see some run hotter than others like this.  Mine runs  170 to 180 with EGT at 1150 to 1200 .



Any rad shop can make you a larger rad.  Take old one in and ask what to do.  Ours are about 80 sq. inches now   4 x 20" -  any adequate although barely at times.

You can try lowering rad about 1 inch or so.  Use  90% water and 10 %  dexcool.



What is your RPM and EGTs ?    Re jetting most likely not needed. If anything , just adjust the stock needles by moving the clip.   Each notch is about 10 to 15% change in fuel flow.



Rad scoops I have one on - not sure if there is again to be had or not. Jury still out  but I did cowl mods and reduced temps in conjuction with the scoop.  I sell Rad scoops as well. 



http://www.cfisher.com/cowl.html

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WurlyBird

Joined: 16 May 2008
Posts: 207
Location: North Pole, Alaska

Posted: Wed Jun 24, 2009 7:11 am Post subject: Re: Gross weight VS DA

Dave, I saw your cowl mods and I like them.  That may be a project for this winter.  I lowered the radiator 1" after I talked to you and it seems to be helping but I still can't control temps enough for an extended taxi after the engine is warm.  I am running about 25% Dex and distilled water.  I have not done a static test and a straight and level WOT test since winter/spring but it was good then, 6250ish static, 6400 in flight if I remember correctly.



My buddy who towed hang gliders with a 582 said they just used bigger radiators so I though something 20" x 5" or similar might add adequate cooling.  Still on the hunt for an answer.

_________________
James
Kitfox 3 / 582 / 70" IVO 2 blade GA
50 hrs on the 582 swapping for HKS 700E and Avid Cowl.

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Wed Jun 24, 2009 10:50 am Post subject: Re: Gross weight VS DA

What temps are you having on the ground and in flight > ?

WurlyBird

Joined: 16 May 2008
Posts: 207
Location: North Pole, Alaska

Posted: Wed Jun 24, 2009 9:02 pm Post subject: Re: Gross weight VS DA

Last flight it was about 85 F and I kept it down to 165-170 for taxi and saw about 185 on climb out, twice.  Low altitude cruise saw about 175-180 and at 5000' it was about 60 F and water was 160-165 at cruise.  My next landing required me to back taxi a few hundred feet and when I got to the end of the runway I was holding 180 so I canceled the flight.



This is with the radiator lowered an inch and running about 25% Dex-cool

_________________
James
Kitfox 3 / 582 / 70" IVO 2 blade GA
50 hrs on the 582 swapping for HKS 700E and Avid Cowl.

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Thu Jun 25, 2009 1:29 am Post subject: Re: Gross weight VS DA

 	  WurlyBird wrote: 	
		  Last flight it was about 85 F and I kept it down to 165-170 for taxi and saw about 185 on climb out, twice.  Low altitude cruise saw about 175-180 and at 5000' it was about 60 F and water was 160-165 at cruise.  My next landing required me to back taxi a few hundred feet and when I got to the end of the runway I was holding 180 so I canceled the flight.



This is with the radiator lowered an inch and running about 25% Dex-cool 	




James,  Sounds pretty good to me and temps don;t get past  185 to 190 F  you should be ok.  Sounds quite typical.  Rotax spec calls for 176 F  but I would round that off normal 160 to 180 normal operating temps and 180 to 190s a caution zone with 200F a area to be danger.

Not all gauges are created equal and I think you will find others run similar.

Guy Buchanan

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

Posted: Thu Jun 25, 2009 5:18 am Post subject: Gross weight VS DA

At 10:02 PM 6/24/2009, you wrote:

 	  Quote: 	
		  Last flight it was about 85 F and I kept it down to 165-170 for taxi 

and saw about 185 on climb out, twice.  Low altitude cruise saw 

about 175-180 and at 5000' it was about 60 F and water was 160-165 

at cruise.  My next landing required me to back taxi a few hundred 

feet and when I got to the end of the runway I was holding 180 so I 

canceled the flight.


	


         Does sound a bit hot to me. Are you running a 160F 

thermostat? (The after-market OMC ones are 160F, versus 135F for 

stock.) Have you checked the thermostat to see if it's broken? (I've 

broken two.) Have you made sure the water pump housing was burped? 

(10mm on top.) Obviously you've checked for line restrictions and 

that the head was burped.

         With a similar radiator lowered 1" I'm good to about 95F 

OAT, (<1500') whereupon I have to be careful taxiing and climbing 

out. Murle sells a thicker aluminum radiator that should lower temps 

quite a bit. I bought one a long time ago but have yet to install it. 

Unfortunately it's just a bit larger than the "Skystar" unit so it 

didn't fit directly in my cowl.





Guy Buchanan

San Diego, CA

K-IV 1200 / 582-C / Warp / 300 hrs. and counting

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

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