Original Posted By: walter evans
Subject: Pietenpol-List: Re: "A" Carb heat>In a message dated 9/14/99 8:23:58 AM Central Daylight Time,>leonstefanhutks(at)webtv.net writes:>> the exhaust pipes are just warm to the touch. If that's so, than not> much HP. would be lost due to carb heat. >>>>Leon,> I disagree. In principal, one of the things that cuts power back when>carb heat muffs are used is that you have significantly altered the ram>airflow into the carburator by routing it thru a heat exchanger. On the A,>you could design the cold air path to have nearly direct ram airflow>available to the carb. Then when "heat" is selected, the pressure drop>across the heat exchanger would be the main cause of reduced power. In the>case of full time carb heat installation, you allways operate with lessthan>optimum airflow......TLB________________________________________________________________________________
Pietenpol-List: "A" Carb heat
Pietenpol-List: Re: "A" Carb heat
Original Posted By: RPas909040(at)aol.com
Subject: Pietenpol-List: Re: "A" Carb heat>Walt,> You are correct in stating that the lower air density is what causes a>drop in hp when carb heat is ON. My statement earlier to Leon wasreferring>to an additional drop in hp that occurs because you are significantly>interrupting air flow with carb heat ON and so the intake air pressure goes>way down. I think Leon was stating that there would be little differencein>hp with carb heat OFF and ON on the model A since the temperature of the>exhaust was "not very hot". I was trying to state that even if the warmair>path didn't add much heat to the intake air, it would still be degradingthe>performance just due to the fact that the air flow path thru the heat muff>drops the pressure significantly. The bottom line is...you makehorsepower>with manifold pressure. So you want dense air and a clean aerodynamic flow>of ram air pressure into the carburator intake to get the manifold pressure>as high as you can. The only catch is...there are times when you have to>sacrifice hp to warm up the intake air to prevent carburator icing. I>certainly wouldn't rig my engine to make that sacrifice full time.> Terry B________________________________________________________________________________
Subject: Pietenpol-List: Re: "A" Carb heat>Walt,> You are correct in stating that the lower air density is what causes a>drop in hp when carb heat is ON. My statement earlier to Leon wasreferring>to an additional drop in hp that occurs because you are significantly>interrupting air flow with carb heat ON and so the intake air pressure goes>way down. I think Leon was stating that there would be little differencein>hp with carb heat OFF and ON on the model A since the temperature of the>exhaust was "not very hot". I was trying to state that even if the warmair>path didn't add much heat to the intake air, it would still be degradingthe>performance just due to the fact that the air flow path thru the heat muff>drops the pressure significantly. The bottom line is...you makehorsepower>with manifold pressure. So you want dense air and a clean aerodynamic flow>of ram air pressure into the carburator intake to get the manifold pressure>as high as you can. The only catch is...there are times when you have to>sacrifice hp to warm up the intake air to prevent carburator icing. I>certainly wouldn't rig my engine to make that sacrifice full time.> Terry B________________________________________________________________________________
Pietenpol-List: Re: "A" Carb heat
Original Posted By: Earl Myers
Subject: Pietenpol-List: Re: "A" Carb heat>Walt,> You are correct in stating that the lower air density is what causes a>drop in hp when carb heat is ON. My statement earlier to Leon wasreferring>to an additional drop in hp that occurs because you are significantly>interrupting air flow with carb heat ON and so the intake air pressure goes>way down. I think Leon was stating that there would be little differencein>hp with carb heat OFF and ON on the model A since the temperature of the>exhaust was "not very hot". I was trying to state that even if the warmair>path didn't add much heat to the intake air, it would still be degradingthe>performance just due to the fact that the air flow path thru the heat muff>drops the pressure significantly. The bottom line is...you makehorsepower>with manifold pressure. So you want dense air and a clean aerodynamic flow>of ram air pressure into the carburator intake to get the manifold pressure>as high as you can. The only catch is...there are times when you have to>sacrifice hp to warm up the intake air to prevent carburator icing. I>certainly wouldn't rig my engine to make that sacrifice full time.> Terry B>>________________________________________________________________________________
Subject: Pietenpol-List: Re: "A" Carb heat>Walt,> You are correct in stating that the lower air density is what causes a>drop in hp when carb heat is ON. My statement earlier to Leon wasreferring>to an additional drop in hp that occurs because you are significantly>interrupting air flow with carb heat ON and so the intake air pressure goes>way down. I think Leon was stating that there would be little differencein>hp with carb heat OFF and ON on the model A since the temperature of the>exhaust was "not very hot". I was trying to state that even if the warmair>path didn't add much heat to the intake air, it would still be degradingthe>performance just due to the fact that the air flow path thru the heat muff>drops the pressure significantly. The bottom line is...you makehorsepower>with manifold pressure. So you want dense air and a clean aerodynamic flow>of ram air pressure into the carburator intake to get the manifold pressure>as high as you can. The only catch is...there are times when you have to>sacrifice hp to warm up the intake air to prevent carburator icing. I>certainly wouldn't rig my engine to make that sacrifice full time.> Terry B>>________________________________________________________________________________
Pietenpol-List: "A" Carb heat
Original Posted By: TomTravis(at)aol.com
Terry: At Bentonpietventure 99, Doug Bryant told me that upon landingthe exhaust pipes are just warm to the touch. If that's so, than notlast week. He said his A Piet performs well at 720 lbs. He said thesecret is higher compression(Al. head) Model B cam, and make a newintake manifold so it can breath better. He used copper pipe fittingsfrom the hardware store. (plumbing section) Leon S.________________________________________________________________________________
Terry: At Bentonpietventure 99, Doug Bryant told me that upon landingthe exhaust pipes are just warm to the touch. If that's so, than notlast week. He said his A Piet performs well at 720 lbs. He said thesecret is higher compression(Al. head) Model B cam, and make a newintake manifold so it can breath better. He used copper pipe fittingsfrom the hardware store. (plumbing section) Leon S.________________________________________________________________________________
Pietenpol-List: Re: "A" Carb heat
Original Posted By: John Duprey
In a message dated 9/14/99 8:23:58 AM Central Daylight Time, leonstefanhutks(at)webtv.net writes:>Leon, I disagree. In principal, one of the things that cuts power back when carb heat muffs are used is that you have significantly altered the ram airflow into the carburator by routing it thru a heat exchanger. On the A, you could design the cold air path to have nearly direct ram airflow available to the carb. Then when "heat" is selected, the pressure drop across the heat exchanger would be the main cause of reduced power. In the case of full time carb heat installation, you allways operate with less than optimum airflow......TLB________________________________________________________________________________
In a message dated 9/14/99 8:23:58 AM Central Daylight Time, leonstefanhutks(at)webtv.net writes:>Leon, I disagree. In principal, one of the things that cuts power back when carb heat muffs are used is that you have significantly altered the ram airflow into the carburator by routing it thru a heat exchanger. On the A, you could design the cold air path to have nearly direct ram airflow available to the carb. Then when "heat" is selected, the pressure drop across the heat exchanger would be the main cause of reduced power. In the case of full time carb heat installation, you allways operate with less than optimum airflow......TLB________________________________________________________________________________
Pietenpol-List: Re: "A" Carb heat
Original Posted By: BARNSTMR(at)aol.com
The reason the RPM drops with carb heat, is that the warm air is thinnerthan cold air so when you add carb heat, the mixture is richened( samefuel/less air= richer). It's not robbing hp by steeling heat from theexhaust pipes.walt-----Original Message-----
The reason the RPM drops with carb heat, is that the warm air is thinnerthan cold air so when you add carb heat, the mixture is richened( samefuel/less air= richer). It's not robbing hp by steeling heat from theexhaust pipes.walt-----Original Message-----
Pietenpol-List: Re: "A" Carb heat
Original Posted By: del magsam
Walt, You are correct in stating that the lower air density is what causes a drop in hp when carb heat is ON. My statement earlier to Leon was referring to an additional drop in hp that occurs because you are significantly interrupting air flow with carb heat ON and so the intake air pressure goes way down. I think Leon was stating that there would be little difference in hp with carb heat OFF and ON on the model A since the temperature of the exhaust was "not very hot". I was trying to state that even if the warm air path didn't add much heat to the intake air, it would still be degrading the performance just due to the fact that the air flow path thru the heat muff drops the pressure significantly. The bottom line is...you make horsepower with manifold pressure. So you want dense air and a clean aerodynamic flow of ram air pressure into the carburator intake to get the manifold pressure as high as you can. The only catch is...there are times when you have to sacrifice hp to warm up the intake air to prevent carburator icing. I certainly wouldn't rig my engine to make that sacrifice full time. Terry B________________________________________________________________________________
Walt, You are correct in stating that the lower air density is what causes a drop in hp when carb heat is ON. My statement earlier to Leon was referring to an additional drop in hp that occurs because you are significantly interrupting air flow with carb heat ON and so the intake air pressure goes way down. I think Leon was stating that there would be little difference in hp with carb heat OFF and ON on the model A since the temperature of the exhaust was "not very hot". I was trying to state that even if the warm air path didn't add much heat to the intake air, it would still be degrading the performance just due to the fact that the air flow path thru the heat muff drops the pressure significantly. The bottom line is...you make horsepower with manifold pressure. So you want dense air and a clean aerodynamic flow of ram air pressure into the carburator intake to get the manifold pressure as high as you can. The only catch is...there are times when you have to sacrifice hp to warm up the intake air to prevent carburator icing. I certainly wouldn't rig my engine to make that sacrifice full time. Terry B________________________________________________________________________________
Pietenpol-List:
Original Posted By: GREA738(at)aol.com
Just studying the blue prints on all the clevisedends on the control stick and landing gear struts. Iwould prefer to machine some ends, insert them intothe tube and weld them on. Instead of heating andshaping them. has anybody done this? thanks for allof your inputs. I have learned much from thisdiscussion group. I appreciate each and every reply!________________________________________________________________________________
Just studying the blue prints on all the clevisedends on the control stick and landing gear struts. Iwould prefer to machine some ends, insert them intothe tube and weld them on. Instead of heating andshaping them. has anybody done this? thanks for allof your inputs. I have learned much from thisdiscussion group. I appreciate each and every reply!________________________________________________________________________________
Pietenpol-List: Re:
Original Posted By: del magsam
In a message dated 09/14/1999 10:50:45 PM Eastern Daylight Time, farmerdel(at)rocketmail.com writes:>If you do use machined inserts think about fishmouthing the ends to distribute stresses. On my Piper motor mount I machined the bolt mount pieces rather than weld a tube to a washer as Piper had. Stronger and looked lots better. For the strut ends I did the heat, squash, wrap & weld outboard and welded a threaded insert inboard. Still flying 20 years later so must be OK.For my Scout - gonna' stick with Bernies plans.DG________________________________________________________________________________
In a message dated 09/14/1999 10:50:45 PM Eastern Daylight Time, farmerdel(at)rocketmail.com writes:>If you do use machined inserts think about fishmouthing the ends to distribute stresses. On my Piper motor mount I machined the bolt mount pieces rather than weld a tube to a washer as Piper had. Stronger and looked lots better. For the strut ends I did the heat, squash, wrap & weld outboard and welded a threaded insert inboard. Still flying 20 years later so must be OK.For my Scout - gonna' stick with Bernies plans.DG________________________________________________________________________________
Pietenpol-List: Re: Re:
Original Posted By: Howard Wilkinson
what do mean by "fishmouthing". I started to heat andsquash, but was bothered by the hammer marks. I mighttry it with a hydraulic press to see if I can get anicer appearing piece.---GREA738(at)aol.com wrote:>> In a message dated 09/14/1999 10:50:45 PM EasternDaylight Time, > farmerdel(at)rocketmail.com writes:> > >> > If you do use machined inserts think aboutfishmouthing the ends to > distribute stresses. On my Piper motor mount Imachined the bolt mount > pieces rather than weld a tube to a washer as Piperhad. Stronger and looked > lots better. For the strut ends I did the heat,squash, wrap & weld outboard > and welded a threaded insert inboard. Still flying20 years later so must be > OK.> For my Scout - gonna' stick with Bernies plans.> DG> ________________________________________________________________________________
what do mean by "fishmouthing". I started to heat andsquash, but was bothered by the hammer marks. I mighttry it with a hydraulic press to see if I can get anicer appearing piece.---GREA738(at)aol.com wrote:>> In a message dated 09/14/1999 10:50:45 PM EasternDaylight Time, > farmerdel(at)rocketmail.com writes:> > >> > If you do use machined inserts think aboutfishmouthing the ends to > distribute stresses. On my Piper motor mount Imachined the bolt mount > pieces rather than weld a tube to a washer as Piperhad. Stronger and looked > lots better. For the strut ends I did the heat,squash, wrap & weld outboard > and welded a threaded insert inboard. Still flying20 years later so must be > OK.> For my Scout - gonna' stick with Bernies plans.> DG> ________________________________________________________________________________
Pietenpol-List: Re: "A" Carb heat
Original Posted By: BARNSTMR(at)aol.com
You guys with the ram air issue...you are on the right track in addition tothe warm/less dense air of carb heat......-----Original Message-----
You guys with the ram air issue...you are on the right track in addition tothe warm/less dense air of carb heat......-----Original Message-----
Pietenpol-List: Re: "A" Carb heat
Original Posted By: BARNSTMR(at)aol.com
Terry,I agree with you 100%. I just wanted to add what I did, because I've flownU/L's for years, and it's a hard thing for the 2 strokers to understand. The2 strokes are very sensitive to temp/density, that when the temp goes down,the colder air makes for a hotter running engine.( fuel the same, more air)walt-----Original Message-----
Terry,I agree with you 100%. I just wanted to add what I did, because I've flownU/L's for years, and it's a hard thing for the 2 strokers to understand. The2 strokes are very sensitive to temp/density, that when the temp goes down,the colder air makes for a hotter running engine.( fuel the same, more air)walt-----Original Message-----