Original Posted By: "TWINBOOM"
In looking through postings and talking to owners of different aircraft,I get very confused about fuel economy. It seems that model A's burn 4gph at ? speed, and corvairs burn 5.5 gph at ? speed. But Rotax enginesof similar HP only burn 2.5 gph. Why the big difference for enginesthat appear to put out similar HP? What speeds/gph do most Piet flyerssee?ThanksMalcolm Morrison________________________________________________________________________________
Pietenpol-List: Fuel economy?
Re: Pietenpol-List: ebay sale
Original Posted By: "Owen Davies"
Well gents, I suppose this is why I monitor the list rather then respond. The fullsize piet, which was a two place/two seater that Roger had plans for, is theone he discontinued, not his single seat Ultra-light version. Please don'tturn this into a big thing. When Mike originally asked about the plane, Iwas just trying to pass on info as to it's origin, and how he could get intouch with that person so he could get his questions answered, nothing more,and no hidden agenda. I don't like bashing folks, and that was not myintent.Doug B.Doug/Elizabeth BlackburnArrowBear Lake Ca.Inland Slope Rebels, Riverside Ca. http://inlandsloperebels.com----- Original Message -----
Well gents, I suppose this is why I monitor the list rather then respond. The fullsize piet, which was a two place/two seater that Roger had plans for, is theone he discontinued, not his single seat Ultra-light version. Please don'tturn this into a big thing. When Mike originally asked about the plane, Iwas just trying to pass on info as to it's origin, and how he could get intouch with that person so he could get his questions answered, nothing more,and no hidden agenda. I don't like bashing folks, and that was not myintent.Doug B.Doug/Elizabeth BlackburnArrowBear Lake Ca.Inland Slope Rebels, Riverside Ca. http://inlandsloperebels.com----- Original Message -----
RE: Pietenpol-List: Fuel economy?
Original Posted By: morrisons5 [mailto:morrisons5(at)adelphia.net]
My first guess would be higher compression, hence more expansion and workfrom each little explosion. But I'm not really up on engines. Any othercomments?Gene-----Original Message-----
My first guess would be higher compression, hence more expansion and workfrom each little explosion. But I'm not really up on engines. Any othercomments?Gene-----Original Message-----
RE: Pietenpol-List: Fuel economy?
Original Posted By: owner-pietenpol-list-server(at)matronics.com
Well, let's see - the model A was developed 75 years ago and burns 4 gphputting out about 30 hp (crusing at 75% power), or 0.133 gallons perhp-hour. The Continental A-65 (developed in 1938) burns about 4.5 gph,putting out 42hp (cruising at 75% power) or 0.107 gallons per hp-hour. TheRotax 912UL puts out 81 hp, or cruises at 58 hp and burns 5.1 gals/hr atcruise, or .088 gallons per hp-hour. Since the Rotax is at least 50 yearsnewer than the Continental, you would expect some gains in efficiency. Ofcourse, the Rotax screams like a banshee, running at 5,000 rpm even whencrusing at 75% power, compared to the satisfying chug of the Continental, orthe even more satisfying chug of the Ford. A large part of the efficeincyof the Rotax comes from operating the engine at that speed, far above thebest operating speed of large diameter propellers, which necessitates ageared engine. The Rotax also sells for $10,000, and is warranteed for afull 100 hours of operation (WhooHoo!). It also carries this warning: Danger!This engine, by its design, is subject to sudden stoppage! Engine stoppagecan result in crash landings. Such crash landings can lead to seriousbodily injury or death.Never fly the aircraft equipped with this engine at locations, airspeeds,altitudes or other circumstances from which a successful no-power landingcanot be made, after sudden engine stoppage. Aircraft equipped with thisengine should only fly in DAYLIGHT VFR conditions.Sort of makes you want to rush right out and plunk down $10K just to hearthat Banshee whine, doesn't it? No thanks, I'll stick with my Continental,with its lovely sound and 1500 hour time between overhauls.Jack -----Original Message-----
Well, let's see - the model A was developed 75 years ago and burns 4 gphputting out about 30 hp (crusing at 75% power), or 0.133 gallons perhp-hour. The Continental A-65 (developed in 1938) burns about 4.5 gph,putting out 42hp (cruising at 75% power) or 0.107 gallons per hp-hour. TheRotax 912UL puts out 81 hp, or cruises at 58 hp and burns 5.1 gals/hr atcruise, or .088 gallons per hp-hour. Since the Rotax is at least 50 yearsnewer than the Continental, you would expect some gains in efficiency. Ofcourse, the Rotax screams like a banshee, running at 5,000 rpm even whencrusing at 75% power, compared to the satisfying chug of the Continental, orthe even more satisfying chug of the Ford. A large part of the efficeincyof the Rotax comes from operating the engine at that speed, far above thebest operating speed of large diameter propellers, which necessitates ageared engine. The Rotax also sells for $10,000, and is warranteed for afull 100 hours of operation (WhooHoo!). It also carries this warning: Danger!This engine, by its design, is subject to sudden stoppage! Engine stoppagecan result in crash landings. Such crash landings can lead to seriousbodily injury or death.Never fly the aircraft equipped with this engine at locations, airspeeds,altitudes or other circumstances from which a successful no-power landingcanot be made, after sudden engine stoppage. Aircraft equipped with thisengine should only fly in DAYLIGHT VFR conditions.Sort of makes you want to rush right out and plunk down $10K just to hearthat Banshee whine, doesn't it? No thanks, I'll stick with my Continental,with its lovely sound and 1500 hour time between overhauls.Jack -----Original Message-----
Re: Pietenpol-List: Fuel economy?
Original Posted By: Jack Phillips
I do not think that you can make the gal/hp/hr comparison you have here. Iknow we have discussed this before (and I still don't understand itcompletely), but torque must enter into the equation, because a 1914 OX5puts out 90 hp at 7-8 gph, while a 90 hp Continental or Franklin may burn4-5 gph, but would not even turn over an OX propeller. Similarly, your $10K"screaming banshee" Rotax would wind itself into the ground before it wouldlift a Champ or Cub with two people in it. The Model A engine has a lotmore torque, so the comparison below is not complete.Gene (not trying to start a fight, just to make sure that the originalperson's question is answered with as much confusion as possible)----- Original Message -----
I do not think that you can make the gal/hp/hr comparison you have here. Iknow we have discussed this before (and I still don't understand itcompletely), but torque must enter into the equation, because a 1914 OX5puts out 90 hp at 7-8 gph, while a 90 hp Continental or Franklin may burn4-5 gph, but would not even turn over an OX propeller. Similarly, your $10K"screaming banshee" Rotax would wind itself into the ground before it wouldlift a Champ or Cub with two people in it. The Model A engine has a lotmore torque, so the comparison below is not complete.Gene (not trying to start a fight, just to make sure that the originalperson's question is answered with as much confusion as possible)----- Original Message -----
RE: Pietenpol-List: Fuel economy?
Original Posted By: ""
Dick,Thanks for the info. We will plan on being there for the 25th.A ride in a Piet would be a great way to celebrate my 57th birthday!Many thanks,Rod Wooller>From: rhartwig11(at)juno.com>Reply-To: pietenpol-list(at)matronics.com>To: pietenpol-list(at)matronics.com>Subject: Pietenpol-List: Re: Pietenpol-List Digest: 1 Msgs - 06/21/02>Date: Sun, 23 Jun 2002 16:10:25 -0500>>>Rod,>AirVenture for 2003 is July 29 to Aug 4. That would mean that Brodhead>would be the weekend before--July 25 thru 27th. I will let you know if I>can confirm that date.>Dick Hartwig>>MSN Photos is the easiest way to share and print your photos: http://photos.msn.com/support/worldwide ... ___Subject: RE: Pietenpol-List: Fuel economy?
Dick,Thanks for the info. We will plan on being there for the 25th.A ride in a Piet would be a great way to celebrate my 57th birthday!Many thanks,Rod Wooller>From: rhartwig11(at)juno.com>Reply-To: pietenpol-list(at)matronics.com>To: pietenpol-list(at)matronics.com>Subject: Pietenpol-List: Re: Pietenpol-List Digest: 1 Msgs - 06/21/02>Date: Sun, 23 Jun 2002 16:10:25 -0500>>>Rod,>AirVenture for 2003 is July 29 to Aug 4. That would mean that Brodhead>would be the weekend before--July 25 thru 27th. I will let you know if I>can confirm that date.>Dick Hartwig>>MSN Photos is the easiest way to share and print your photos: http://photos.msn.com/support/worldwide ... ___Subject: RE: Pietenpol-List: Fuel economy?
Original Posted By: Mike Hardaway
Group,I findthat least for me it helps to remember tha hourse power is a marketing turminvented to sell steam engines.It is a rate function where as, torque, is purely a measure of force. The old model A withits long stroke is capable of doing a lot of work at a relitivly low rate wherethe rotax relies heavly on its ability to turn very fast in order to swing thehourse power equation in its favor. big slow turning engines use more of theheat thay produce to genereate real work than small high reving ones. The mostefficient internal combustion engines in the world are very large diesels usein direct drive ship propulsion.Sulzer diesel built a 6 cylinder diesel which was 53% thermal efficient. The best auto engines struggle to beat 30%.As far as economy and theAir Camper I'm sure drag is the overideing factorregardless of the powerplant on the nose. So much energy is wasted pushing a highlift high drag airfoil stuts wires and everthing else along that economy justisen't why we build and fly them.GeneIn St Louis------------------------------------------------Can a Web portal forever change your life?Win up to $25 Million on iWon - click here!________________________________________________________________________________Date: Sat, 29 Jun 2002 00:01:20 -0700
Group,I findthat least for me it helps to remember tha hourse power is a marketing turminvented to sell steam engines.It is a rate function where as, torque, is purely a measure of force. The old model A withits long stroke is capable of doing a lot of work at a relitivly low rate wherethe rotax relies heavly on its ability to turn very fast in order to swing thehourse power equation in its favor. big slow turning engines use more of theheat thay produce to genereate real work than small high reving ones. The mostefficient internal combustion engines in the world are very large diesels usein direct drive ship propulsion.Sulzer diesel built a 6 cylinder diesel which was 53% thermal efficient. The best auto engines struggle to beat 30%.As far as economy and theAir Camper I'm sure drag is the overideing factorregardless of the powerplant on the nose. So much energy is wasted pushing a highlift high drag airfoil stuts wires and everthing else along that economy justisen't why we build and fly them.GeneIn St Louis------------------------------------------------Can a Web portal forever change your life?Win up to $25 Million on iWon - click here!________________________________________________________________________________Date: Sat, 29 Jun 2002 00:01:20 -0700
> > Pietenpol-List: Fuel economy?
Original Posted By: Gary Gower
> > RE: Pietenpol-List: Fuel economy?
Original Posted By: Mike Hardaway
RE: Pietenpol-List: Fuel economy?
Original Posted By: "walter evans"
The compairison of specific fuel consumption that Jack made is correct. Andit is true that newer engine designs provide effeciencies due to moreeffecient combustion chamber design, better bearings, and better fuelmanagement. Although the compairisons are misleading when it comes toaircraft performance in the fact that it requires an exponentiallyincreasing amount of horsepower to move a thing faster through the air. Weall know that 80 HP does not move an aircraft twice as fast as 40 HP(although it climbs a hell of a lot better).The other misleading item is the HP rating of an engine and the actualoutput and/or torque at your chosen RPM. There is quite a bit that could bewritten here but its basically all about cubic inches. A Model A engine,which is rated for 40 horses is 200 cubic inches. It's a huge engine foronly 40 HP and to a large part, that is why it's a "high torque" engine. Ifit had a different intake system and the timing of the spark and valves wereoptomized for a higher RPM, it would deliver like traditional 200 CIengines, although structurally it's not capable of withstanding the outputthe 200 CI could deliver. What I mean to say here is that its possible torate this engine at 80 HP, with intake modifications, but only every run itat 30 HP... at 4 GPH. Then we would all be referencing this 80 HP enginewith a 4 GPH burn. Jack Phillips was aware of this when he stated thespecific fuel consuptions, he used output numbers, not engine ratings.Robert HainesDu Quoin, Illinois________________________________________________________________________________
The compairison of specific fuel consumption that Jack made is correct. Andit is true that newer engine designs provide effeciencies due to moreeffecient combustion chamber design, better bearings, and better fuelmanagement. Although the compairisons are misleading when it comes toaircraft performance in the fact that it requires an exponentiallyincreasing amount of horsepower to move a thing faster through the air. Weall know that 80 HP does not move an aircraft twice as fast as 40 HP(although it climbs a hell of a lot better).The other misleading item is the HP rating of an engine and the actualoutput and/or torque at your chosen RPM. There is quite a bit that could bewritten here but its basically all about cubic inches. A Model A engine,which is rated for 40 horses is 200 cubic inches. It's a huge engine foronly 40 HP and to a large part, that is why it's a "high torque" engine. Ifit had a different intake system and the timing of the spark and valves wereoptomized for a higher RPM, it would deliver like traditional 200 CIengines, although structurally it's not capable of withstanding the outputthe 200 CI could deliver. What I mean to say here is that its possible torate this engine at 80 HP, with intake modifications, but only every run itat 30 HP... at 4 GPH. Then we would all be referencing this 80 HP enginewith a 4 GPH burn. Jack Phillips was aware of this when he stated thespecific fuel consuptions, he used output numbers, not engine ratings.Robert HainesDu Quoin, Illinois________________________________________________________________________________