Original Posted By: "Oscar Zuniga"
Dear Oscar,Your comments about leaving well enough alone with the design are well takenIF nothing else is changed but the spars. The history of Pietenpolcertainly substantiates this.However, many of us have raised the empty weight of the airframe by usinglarger engines, electrical systems, more fuel for the larger engine, brakes,tailwheels and so on. This has resulted in a heavier gross weight of asmuch as as 1250 pounds, more than 200 pounds heavier than the originaldesign. I believe there was an informal weight and balance exercise atBrodhead several years ago with the results published in the BPA newletter.It was amazing how the planes varied from the original design in regard toweight and balance. Most were much heavier than originally designed.This indicates to me that the design has a strong and forgiving airframe,but I don't wish to find out where the limits are. I would prefer to lookat all those parts which may be impacted by any changes in the weight ordesign and that would also include how the spars are attached to the rest ofthe plane. I would appreciate hearing more from you on the subject.Cordially, John Dilatush, Salida CO.dilatush(at)amigo.net>>________________________________________________________________________________
Pietenpol-List: Alternative spars
Pietenpol-List: Alternative spars
Original Posted By: Larry Neal
John wrote:>many of us have raised the empty weight of the airframe by using>larger engines, electrical systems, more fuel for the larger engine,>brakes, tailwheels and so on.>there was an informal weight and balance exercise at Brodhead>Most were much heavier than originally designed.>I would prefer to look at all those parts which may be impacted>by any changes in the weight or design and that would also include>how the spars are attached to the rest of the plane.Well, my opinion is just that: an opinion. All I have is a set of plans and a keen interest in learning all I can about the Piet before I start building. But what I see is what happens with almost every homebuilt: the prototype is the lightest, simplest one of its type. All those following are usually heavier and more complex. Yes, they often are far nicer than the prototype, but isn't that the purpose of the first one, anyway? We see a great new design at an airshow or in a write-up, we get excited, and we start building. And improving. Tremendous value in getting more hands, eyes, and minds in on it- as we see by the many tips and tricks, and elegant improvements in this grand old design. So the question is, what happens when we start making changes outside of the envelope that the designer allowed for? We're experimenters; we experiment!In my opinion, it is far more beneficial to build in lightness (to quote BHP) than to re-design things to handle additional weight. The 3-piece wing adds weight, but solves the problem of building space. I hope not to have the space problem when I get started, so I'll build a one-piece wing. Brakes and tailwheel add weight, but solve the problem of operating off of hard surface runways and in crosswinds. I will have to live with this. More fuel adds weight, but solves the problem of only being able to go for short hops. This, too, is a necessity for me; I plan to go to fly-ins and have fun in the airplane and not have to stop every 90 minutes for fuel. An electrical system adds weight, but provides power for strobes, radios, instruments, and other nice items. I don't think the Pietenpol needs an electrical system, so I won't have one.So one reason why we voluntarily add weight is to add features, whether they are necessary for expanding the capabilities of the airplane or just "nice to have".The other big factor is money, since obviously that is a huge factor in why many of us are homebuilders: we simply can't afford the shrink-wrap kits or the factory jobs (or even the beat-up old certified aircraft out there). When it comes to money, we get creative, we start really thinking, and ingenuity kicks into high gear. The alternative spars fall into that area, in my opinion.Box spars, or I-section spars, don't have to be heavier than solid wood spars. On the contrary, properly engineered and constructed, they can be equivalent in weight; perhaps even lighter. The important thing to many of us is that they can be made at far less cost than the stock, solid items.If we're talking about analyzing the Pietenpol so that we can re-design the weak points in search of a safe increase in max gross, that's a whole 'nother issue, and it starts with a person who has the fire in their belly to start that ball rolling. That's not me. I like the design and simply want to be able to build it affordably. That being the case, it seems far easier to me to build in lightness, do without the bells, whistles, gauges, and fancy paint- and enjoy leisurely cruise speeds but decent climb performance, always with the ability to put someone in the front seat and still fly safely. Upping the empty weight works against all of those things. Beefing up fittings and structure without analyzing things ("eyeball engineering", or TLAR- "that looks about right") tends to increase empty weight. It is for that reason that I'm interested in re-engineering anything that will (1) simplify the construction, (2) make it lighter with equivalent strength, or (3) lower the cost... but I'm really not out to create a "fat Piet" when a skinny one will do.Oscar ZunigaMedford, Oregonmailto: taildrags(at)hotmail.comwebsite at http://www.flysquirrel.net________________________________________________________________________________Date: Sat, 01 Dec 2001 18:56:46 -0600
John wrote:>many of us have raised the empty weight of the airframe by using>larger engines, electrical systems, more fuel for the larger engine,>brakes, tailwheels and so on.>there was an informal weight and balance exercise at Brodhead>Most were much heavier than originally designed.>I would prefer to look at all those parts which may be impacted>by any changes in the weight or design and that would also include>how the spars are attached to the rest of the plane.Well, my opinion is just that: an opinion. All I have is a set of plans and a keen interest in learning all I can about the Piet before I start building. But what I see is what happens with almost every homebuilt: the prototype is the lightest, simplest one of its type. All those following are usually heavier and more complex. Yes, they often are far nicer than the prototype, but isn't that the purpose of the first one, anyway? We see a great new design at an airshow or in a write-up, we get excited, and we start building. And improving. Tremendous value in getting more hands, eyes, and minds in on it- as we see by the many tips and tricks, and elegant improvements in this grand old design. So the question is, what happens when we start making changes outside of the envelope that the designer allowed for? We're experimenters; we experiment!In my opinion, it is far more beneficial to build in lightness (to quote BHP) than to re-design things to handle additional weight. The 3-piece wing adds weight, but solves the problem of building space. I hope not to have the space problem when I get started, so I'll build a one-piece wing. Brakes and tailwheel add weight, but solve the problem of operating off of hard surface runways and in crosswinds. I will have to live with this. More fuel adds weight, but solves the problem of only being able to go for short hops. This, too, is a necessity for me; I plan to go to fly-ins and have fun in the airplane and not have to stop every 90 minutes for fuel. An electrical system adds weight, but provides power for strobes, radios, instruments, and other nice items. I don't think the Pietenpol needs an electrical system, so I won't have one.So one reason why we voluntarily add weight is to add features, whether they are necessary for expanding the capabilities of the airplane or just "nice to have".The other big factor is money, since obviously that is a huge factor in why many of us are homebuilders: we simply can't afford the shrink-wrap kits or the factory jobs (or even the beat-up old certified aircraft out there). When it comes to money, we get creative, we start really thinking, and ingenuity kicks into high gear. The alternative spars fall into that area, in my opinion.Box spars, or I-section spars, don't have to be heavier than solid wood spars. On the contrary, properly engineered and constructed, they can be equivalent in weight; perhaps even lighter. The important thing to many of us is that they can be made at far less cost than the stock, solid items.If we're talking about analyzing the Pietenpol so that we can re-design the weak points in search of a safe increase in max gross, that's a whole 'nother issue, and it starts with a person who has the fire in their belly to start that ball rolling. That's not me. I like the design and simply want to be able to build it affordably. That being the case, it seems far easier to me to build in lightness, do without the bells, whistles, gauges, and fancy paint- and enjoy leisurely cruise speeds but decent climb performance, always with the ability to put someone in the front seat and still fly safely. Upping the empty weight works against all of those things. Beefing up fittings and structure without analyzing things ("eyeball engineering", or TLAR- "that looks about right") tends to increase empty weight. It is for that reason that I'm interested in re-engineering anything that will (1) simplify the construction, (2) make it lighter with equivalent strength, or (3) lower the cost... but I'm really not out to create a "fat Piet" when a skinny one will do.Oscar ZunigaMedford, Oregonmailto: taildrags(at)hotmail.comwebsite at http://www.flysquirrel.net________________________________________________________________________________Date: Sat, 01 Dec 2001 18:56:46 -0600
> Pietenpol-List: Alternative spars
Original Posted By: Jim Malley
Well spoken Oscar. I agree whole heartedly. That's been my philosophy as well. I once sat in the front seat of a 1940 J-3 cub and flew over the flower fields of Lompoc California watching the little cork float fuel gage and felt great comfort in the simplicity and beauty of it all.I'm still game for laser cutting and will be glad to help if/when I can.Allen Smith>From: "Oscar Zuniga" >Reply-To: pietenpol-list(at)matronics.com>To: dilatush(at)amigo.net>Subject: Pietenpol-List: Alternative spars>Date: Sat, 01 Dec 2001 23:59:10>>>>John wrote:>> >many of us have raised the empty weight of the airframe by using> >larger engines, electrical systems, more fuel for the larger engine,> >brakes, tailwheels and so on.> >there was an informal weight and balance exercise at Brodhead> >Most were much heavier than originally designed.> >I would prefer to look at all those parts which may be impacted> >by any changes in the weight or design and that would also include> >how the spars are attached to the rest of the plane.>>Well, my opinion is just that: an opinion. All I have is a set of plans >and>a keen interest in learning all I can about the Piet before I start>building. But what I see is what happens with almost every homebuilt: the>prototype is the lightest, simplest one of its type. All those following>are usually heavier and more complex. Yes, they often are far nicer than>the prototype, but isn't that the purpose of the first one, anyway? We see>a great new design at an airshow or in a write-up, we get excited, and we>start building. And improving. Tremendous value in getting more hands,>eyes, and minds in on it- as we see by the many tips and tricks, and >elegant>improvements in this grand old design. So the question is, what happens>when we start making changes outside of the envelope that the designer>allowed for? We're experimenters; we experiment!>>In my opinion, it is far more beneficial to build in lightness (to quote>BHP) than to re-design things to handle additional weight. The 3-piece >wing>adds weight, but solves the problem of building space. I hope not to have>the space problem when I get started, so I'll build a one-piece wing.>Brakes and tailwheel add weight, but solve the problem of operating off of>hard surface runways and in crosswinds. I will have to live with this.>More fuel adds weight, but solves the problem of only being able to go for>short hops. This, too, is a necessity for me; I plan to go to fly-ins and>have fun in the airplane and not have to stop every 90 minutes for fuel. >An>electrical system adds weight, but provides power for strobes, radios,>instruments, and other nice items. I don't think the Pietenpol needs an>electrical system, so I won't have one.>>So one reason why we voluntarily add weight is to add features, whether >they>are necessary for expanding the capabilities of the airplane or just "nice>to have".>>The other big factor is money, since obviously that is a huge factor in why>many of us are homebuilders: we simply can't afford the shrink-wrap kits or>the factory jobs (or even the beat-up old certified aircraft out there).>When it comes to money, we get creative, we start really thinking, and>ingenuity kicks into high gear. The alternative spars fall into that area,>in my opinion.>>Box spars, or I-section spars, don't have to be heavier than solid wood>spars. On the contrary, properly engineered and constructed, they can be>equivalent in weight; perhaps even lighter. The important thing to many of>us is that they can be made at far less cost than the stock, solid items.>>If we're talking about analyzing the Pietenpol so that we can re-design the>weak points in search of a safe increase in max gross, that's a whole>'nother issue, and it starts with a person who has the fire in their belly>to start that ball rolling. That's not me. I like the design and simply>want to be able to build it affordably. That being the case, it seems far>easier to me to build in lightness, do without the bells, whistles, gauges,>and fancy paint- and enjoy leisurely cruise speeds but decent climb>performance, always with the ability to put someone in the front seat and>still fly safely. Upping the empty weight works against all of those>things. Beefing up fittings and structure without analyzing things>("eyeball engineering", or TLAR- "that looks about right") tends to >increase>empty weight. It is for that reason that I'm interested in re-engineering>anything that will (1) simplify the construction, (2) make it lighter with>equivalent strength, or (3) lower the cost... but I'm really not out to>create a "fat Piet" when a skinny one will do.>>Oscar Zuniga>Medford, Oregon>mailto: taildrags(at)hotmail.com>website at http://www.flysquirrel.net>>________________________________________________________________________________Date: Sun, 02 Dec 2001 12:20:48 -0500
Well spoken Oscar. I agree whole heartedly. That's been my philosophy as well. I once sat in the front seat of a 1940 J-3 cub and flew over the flower fields of Lompoc California watching the little cork float fuel gage and felt great comfort in the simplicity and beauty of it all.I'm still game for laser cutting and will be glad to help if/when I can.Allen Smith>From: "Oscar Zuniga" >Reply-To: pietenpol-list(at)matronics.com>To: dilatush(at)amigo.net>Subject: Pietenpol-List: Alternative spars>Date: Sat, 01 Dec 2001 23:59:10>>>>John wrote:>> >many of us have raised the empty weight of the airframe by using> >larger engines, electrical systems, more fuel for the larger engine,> >brakes, tailwheels and so on.> >there was an informal weight and balance exercise at Brodhead> >Most were much heavier than originally designed.> >I would prefer to look at all those parts which may be impacted> >by any changes in the weight or design and that would also include> >how the spars are attached to the rest of the plane.>>Well, my opinion is just that: an opinion. All I have is a set of plans >and>a keen interest in learning all I can about the Piet before I start>building. But what I see is what happens with almost every homebuilt: the>prototype is the lightest, simplest one of its type. All those following>are usually heavier and more complex. Yes, they often are far nicer than>the prototype, but isn't that the purpose of the first one, anyway? We see>a great new design at an airshow or in a write-up, we get excited, and we>start building. And improving. Tremendous value in getting more hands,>eyes, and minds in on it- as we see by the many tips and tricks, and >elegant>improvements in this grand old design. So the question is, what happens>when we start making changes outside of the envelope that the designer>allowed for? We're experimenters; we experiment!>>In my opinion, it is far more beneficial to build in lightness (to quote>BHP) than to re-design things to handle additional weight. The 3-piece >wing>adds weight, but solves the problem of building space. I hope not to have>the space problem when I get started, so I'll build a one-piece wing.>Brakes and tailwheel add weight, but solve the problem of operating off of>hard surface runways and in crosswinds. I will have to live with this.>More fuel adds weight, but solves the problem of only being able to go for>short hops. This, too, is a necessity for me; I plan to go to fly-ins and>have fun in the airplane and not have to stop every 90 minutes for fuel. >An>electrical system adds weight, but provides power for strobes, radios,>instruments, and other nice items. I don't think the Pietenpol needs an>electrical system, so I won't have one.>>So one reason why we voluntarily add weight is to add features, whether >they>are necessary for expanding the capabilities of the airplane or just "nice>to have".>>The other big factor is money, since obviously that is a huge factor in why>many of us are homebuilders: we simply can't afford the shrink-wrap kits or>the factory jobs (or even the beat-up old certified aircraft out there).>When it comes to money, we get creative, we start really thinking, and>ingenuity kicks into high gear. The alternative spars fall into that area,>in my opinion.>>Box spars, or I-section spars, don't have to be heavier than solid wood>spars. On the contrary, properly engineered and constructed, they can be>equivalent in weight; perhaps even lighter. The important thing to many of>us is that they can be made at far less cost than the stock, solid items.>>If we're talking about analyzing the Pietenpol so that we can re-design the>weak points in search of a safe increase in max gross, that's a whole>'nother issue, and it starts with a person who has the fire in their belly>to start that ball rolling. That's not me. I like the design and simply>want to be able to build it affordably. That being the case, it seems far>easier to me to build in lightness, do without the bells, whistles, gauges,>and fancy paint- and enjoy leisurely cruise speeds but decent climb>performance, always with the ability to put someone in the front seat and>still fly safely. Upping the empty weight works against all of those>things. Beefing up fittings and structure without analyzing things>("eyeball engineering", or TLAR- "that looks about right") tends to >increase>empty weight. It is for that reason that I'm interested in re-engineering>anything that will (1) simplify the construction, (2) make it lighter with>equivalent strength, or (3) lower the cost... but I'm really not out to>create a "fat Piet" when a skinny one will do.>>Oscar Zuniga>Medford, Oregon>mailto: taildrags(at)hotmail.com>website at http://www.flysquirrel.net>>________________________________________________________________________________Date: Sun, 02 Dec 2001 12:20:48 -0500