Original Posted By: "Gene Rambo"
Gene,Thanks. I have the ash cross pieces. But, I am wondering whether you orothers are putting the "optional" 2" wide steel cross member under thefuselage between the landing gear attach points?Ted----- Original Message -----
Pietenpol-List: Landing gear reinforcement straps
Re: Pietenpol-List: Landing gear reinforcement straps
Original Posted By: Ted Brousseau
I wasn't aware that the steel reinforcement was that wide (2") but don'thave the plans in fromt of me. I wouldn't make it that wide, I thought itwas something like 1/2". In fact, I'm not sure whether I am going to put itin at all, given that I too have the ash cross pieces which should sufficefor any strength across that area. With this set up, and using the spreaderbar type gear, you have to use modified fittings like the FrankPavliga-style fittings.Gene----- Original Message -----
I wasn't aware that the steel reinforcement was that wide (2") but don'thave the plans in fromt of me. I wouldn't make it that wide, I thought itwas something like 1/2". In fact, I'm not sure whether I am going to put itin at all, given that I too have the ash cross pieces which should sufficefor any strength across that area. With this set up, and using the spreaderbar type gear, you have to use modified fittings like the FrankPavliga-style fittings.Gene----- Original Message -----
RE: Pietenpol-List: Airfoil
Original Posted By: owner-pietenpol-list-server(at)matronics.com
THANK YOU KEVIN!!!!Your website has the only known picture of my friends Monocoupe 90 in itsoriginal Stanavo paint scheme. I have been looking for a picture of thisNC11753 for the last twelve years. Restoration has been on hold for a whilenow until a picture turned up AND YOU HAVE IT!!Astronaut Buzz Aldrin's old man was a corporate pilot for Stanavo andundoubtedly flew this ship.Might you have the original photo or know the source of this or others?Chris Bobka-----Original Message-----
THANK YOU KEVIN!!!!Your website has the only known picture of my friends Monocoupe 90 in itsoriginal Stanavo paint scheme. I have been looking for a picture of thisNC11753 for the last twelve years. Restoration has been on hold for a whilenow until a picture turned up AND YOU HAVE IT!!Astronaut Buzz Aldrin's old man was a corporate pilot for Stanavo andundoubtedly flew this ship.Might you have the original photo or know the source of this or others?Chris Bobka-----Original Message-----
Pietenpol-List: Airfoil
Original Posted By: "Gary McNeel, Jr."
Re: Pietenpol-List: Landing gear reinforcement straps
Original Posted By: "Ted Brousseau"
Ted,I think that the cross straps may serve another function, other thanreinforcing the landing gear. I think that they connect the left and rightlift struts. The lift struts want to pull away from the fuselage as thewings lift the weight of the airplane. Without the cross strap, you arerelying on a bracket bolted wood to take up this force, without the boltspulling out through the edges of the wood. Granted, the wood is a 1" pieceof Ash, but steel does much better in tensile strength.Malcolm----- Original Message -----
Ted,I think that the cross straps may serve another function, other thanreinforcing the landing gear. I think that they connect the left and rightlift struts. The lift struts want to pull away from the fuselage as thewings lift the weight of the airplane. Without the cross strap, you arerelying on a bracket bolted wood to take up this force, without the boltspulling out through the edges of the wood. Granted, the wood is a 1" pieceof Ash, but steel does much better in tensile strength.Malcolm----- Original Message -----
Re: Pietenpol-List: Landing gear reinforcement straps
Original Posted By: "Hubbard, Eugene"
Ted,As designed, the Pietenpol had a one-piece wing which madethe use of steel reinforcing straps between the lift strut/landinggear fittings optional.With a three piece wing, the lift loads through the struts will behigher than with the one-piece setup, and using these strapsis advisable. The ash crosspiece between the fittings is goodfor resisting compression, but not too reliable for tensile loadsbecause the attaching bolts concentrate them in the wood.For this reason, I chose to include the straps on my Pietenpolbetween both front and rear strut fittings. In addition, I welded(edges only) the fittings to the tie straps (my term) so that thethe whole assembly could be bolted to the fuselage as a unit.This is one area where I decided to not try to save weight, wish-ing to ensure reliability and durability. In any case, I doubt I ad-ded more than a couple of pounds and the setup has proven itself during literally thousands of takeoffs and landings fromrough fields.Cheers,Graham ________________________________________________________________________________
Ted,As designed, the Pietenpol had a one-piece wing which madethe use of steel reinforcing straps between the lift strut/landinggear fittings optional.With a three piece wing, the lift loads through the struts will behigher than with the one-piece setup, and using these strapsis advisable. The ash crosspiece between the fittings is goodfor resisting compression, but not too reliable for tensile loadsbecause the attaching bolts concentrate them in the wood.For this reason, I chose to include the straps on my Pietenpolbetween both front and rear strut fittings. In addition, I welded(edges only) the fittings to the tie straps (my term) so that thethe whole assembly could be bolted to the fuselage as a unit.This is one area where I decided to not try to save weight, wish-ing to ensure reliability and durability. In any case, I doubt I ad-ded more than a couple of pounds and the setup has proven itself during literally thousands of takeoffs and landings fromrough fields.Cheers,Graham ________________________________________________________________________________
RE: Pietenpol-List: Landing gear reinforcement straps
Original Posted By: Graham Hansen [mailto:grhans@cable-lynx.net]
The one-piece wing isn't stiff enough to change the tension on the bottom ofthe fuselage. Besides, if you work out the stresses, it appears that theonly force the center section is seeing is compression.Gene-----Original Message-----
The one-piece wing isn't stiff enough to change the tension on the bottom ofthe fuselage. Besides, if you work out the stresses, it appears that theonly force the center section is seeing is compression.Gene-----Original Message-----
Re: Pietenpol-List: Landing gear reinforcement straps
Original Posted By: "Gene Rambo"
I put them on mine. My mentor just seemed to point to it on the plans,early on ,and said "make sure you put those on".Didn't seem that hard to do. after the gear was on , and the fuse wasupside down anyway, just lay the straps accross and mark out the holes. ( Ididn't have straps long enough so I welded two shorter pieces together, so Ihave a "lump" in the center.) You'll have to grind out strange shapes onboth ends of the front straps due to the tabs that are put on for the bungeetubes. But when you're done you'll have a continous steel structure downone wing strut, accross the bottom, and up the other wing strut. (Comfortingwhen you're doing steep turns at 3000 ft. and your cheeks are pulling downto your neck.)walt----- Original Message -----
I put them on mine. My mentor just seemed to point to it on the plans,early on ,and said "make sure you put those on".Didn't seem that hard to do. after the gear was on , and the fuse wasupside down anyway, just lay the straps accross and mark out the holes. ( Ididn't have straps long enough so I welded two shorter pieces together, so Ihave a "lump" in the center.) You'll have to grind out strange shapes onboth ends of the front straps due to the tabs that are put on for the bungeetubes. But when you're done you'll have a continous steel structure downone wing strut, accross the bottom, and up the other wing strut. (Comfortingwhen you're doing steep turns at 3000 ft. and your cheeks are pulling downto your neck.)walt----- Original Message -----
Re: Pietenpol-List: Landing gear reinforcement straps
Original Posted By: "morrisons5"
Thanks Malcolm, Walt and Graham. I kept thinking about the forces from thelanding gear. Never considered the lift struts. They are probably the mostimportant part on the plane. So, I will definitely be using the strap. Themembers of this list are the greatest people on earth.Happy holidays.Ted----- Original Message -----
Thanks Malcolm, Walt and Graham. I kept thinking about the forces from thelanding gear. Never considered the lift struts. They are probably the mostimportant part on the plane. So, I will definitely be using the strap. Themembers of this list are the greatest people on earth.Happy holidays.Ted----- Original Message -----
Re: Pietenpol-List: Landing gear reinforcement straps
Original Posted By: "Christian Bobka"
Gene,I never did calculate the loads in comparing the one-piece to thethree piece wing. But I suspected (incorrectly it seems) that theone- piece wing would have enough stiffness to reduce the ten-sile loads across the lower fuselage somewhat. With the hingedouter panels of my three-piece wing I thought there would be zero stiffness and made sure I installed the straps.From your conclusions, it seems that EVERY PIETENPOL with a wooden fuselage should have these reinforcement straps, regard-less. Thanks for the information! Cheers,Graham________________________________________________________________________________
Gene,I never did calculate the loads in comparing the one-piece to thethree piece wing. But I suspected (incorrectly it seems) that theone- piece wing would have enough stiffness to reduce the ten-sile loads across the lower fuselage somewhat. With the hingedouter panels of my three-piece wing I thought there would be zero stiffness and made sure I installed the straps.From your conclusions, it seems that EVERY PIETENPOL with a wooden fuselage should have these reinforcement straps, regard-less. Thanks for the information! Cheers,Graham________________________________________________________________________________
RE: Pietenpol-List: Landing gear reinforcement straps
Original Posted By: owner-pietenpol-list-server(at)matronics.com
one more question: The spreader bar gear as viewed from the front in the F/GPage 7shows the landing gear cross bracing cables in line with the lift struts. Isit right thatthis would carry the lift strut tension loads through to the spreader barand the in compressionacross to the opposite side? Seems like the spreader bar gear would addstrength and the fuse bottomwould not be subjected to as great a load.John Mc-----Original Message-----
one more question: The spreader bar gear as viewed from the front in the F/GPage 7shows the landing gear cross bracing cables in line with the lift struts. Isit right thatthis would carry the lift strut tension loads through to the spreader barand the in compressionacross to the opposite side? Seems like the spreader bar gear would addstrength and the fuse bottomwould not be subjected to as great a load.John Mc-----Original Message-----
Re: Pietenpol-List: Landing gear reinforcement straps
Original Posted By: Kip & Beth Gardner
RE: Pietenpol-List: Landing gear reinforcement straps
Original Posted By: owner-pietenpol-list-server(at)matronics.com
I see your point John but the spreader bars would be kind of weak incompression due to their small cross section...Euler's formula...20:1 lengthto diameter ratio exceeded, etc...when the gear is under normal landing loads, the spreader is in tension andthat is the type load it was designed for.With a one piece wing, lift loads, due to the center portion of the wingarea, in the cabane struts is minimal in tension. With a two piece wing,due to its hinge like pin(s), the tension loads in the cabane go up due tolift loads. Yet if the wing tips are trying to fold up, with either a oneor multiple piece wing, the fuselage box and the cabane struts are trying tohold the strut attach point on the fuselage a fixed distance from the wingmaking this load a compression load. As a result, the multiple piece wingcould get by with less material becuase the loads would counter each otherand cancel one or the other out completely.Either way, there is a definite tensile load on the fuselage between thelift strut attach points. I would think it a good idea to take a liitle ofthe wood away and let some steel carry the load. It would not have to bemuch. A rough calculation that can be refined by our expert engineers:Figure 1100 lb gross wieght at 6 gs including the safety factor split evenlymore or less into one forward and one aft is 3300lb tensile load per strap.4130 is at 90000 psi tensile strength so you need about .04 square inches ofmaterial. So a .090" thick by .5 " wide would give you .045 square inches.You could embed it in epoxy in the crosspiece/plywood floor between the wingstrut attach fittings and nobody would ever no it was there....but you.chris bobka-----Original Message-----
I see your point John but the spreader bars would be kind of weak incompression due to their small cross section...Euler's formula...20:1 lengthto diameter ratio exceeded, etc...when the gear is under normal landing loads, the spreader is in tension andthat is the type load it was designed for.With a one piece wing, lift loads, due to the center portion of the wingarea, in the cabane struts is minimal in tension. With a two piece wing,due to its hinge like pin(s), the tension loads in the cabane go up due tolift loads. Yet if the wing tips are trying to fold up, with either a oneor multiple piece wing, the fuselage box and the cabane struts are trying tohold the strut attach point on the fuselage a fixed distance from the wingmaking this load a compression load. As a result, the multiple piece wingcould get by with less material becuase the loads would counter each otherand cancel one or the other out completely.Either way, there is a definite tensile load on the fuselage between thelift strut attach points. I would think it a good idea to take a liitle ofthe wood away and let some steel carry the load. It would not have to bemuch. A rough calculation that can be refined by our expert engineers:Figure 1100 lb gross wieght at 6 gs including the safety factor split evenlymore or less into one forward and one aft is 3300lb tensile load per strap.4130 is at 90000 psi tensile strength so you need about .04 square inches ofmaterial. So a .090" thick by .5 " wide would give you .045 square inches.You could embed it in epoxy in the crosspiece/plywood floor between the wingstrut attach fittings and nobody would ever no it was there....but you.chris bobka-----Original Message-----
Re: Pietenpol-List: Landing gear reinforcement straps
Original Posted By: "The Huizenga's"
Re: Pietenpol-List: engine choices
Original Posted By: "The Huizenga's"
RE: Pietenpol-List: Landing gear reinforcement straps
Original Posted By: owner-pietenpol-list-server(at)matronics.com
Thanks for your input Chris.I'm sure I will put the strips in. Peace of mind as well as goodengineering.by the way I'm glad "fisherman" didn't chase you away permanently.I value your input to this list.-----Original Message-----
Thanks for your input Chris.I'm sure I will put the strips in. Peace of mind as well as goodengineering.by the way I'm glad "fisherman" didn't chase you away permanently.I value your input to this list.-----Original Message-----
RE: Pietenpol-List: Airfoil
Original Posted By: owner-pietenpol-list-server(at)matronics.com
Kevin,I agree with you about the attitude of the EAA Library. You can't get muchdone there when you are trying to research something. I would think thatthe people that donated stuff to get the library up and going would bepretty mad if they knew that the paying members like you and I really don'thave the ability to use the library as one would think it should be used.Chris Bobka-----Original Message-----
Kevin,I agree with you about the attitude of the EAA Library. You can't get muchdone there when you are trying to research something. I would think thatthe people that donated stuff to get the library up and going would bepretty mad if they knew that the paying members like you and I really don'thave the ability to use the library as one would think it should be used.Chris Bobka-----Original Message-----
RE: Pietenpol-List: Landing gear reinforcement straps
Original Posted By: "Oscar Zuniga"
Chris,I don't see that the one-piece wing can possibly be stiff enough to affectthe cabane and lift strut loading ratios. My reasoning is that I have nodoubt that I could, with hand pressure, flex the one-piece wing with thecabane struts removed such that the distance between atatch points changesmeasurably. This is really a crude way of establishing a Young's modulus ofmaybe a few hundred to a thousand pounds per inch of displacement.Similarly, I cannot imagine, under any circumstances, changing the length ofthe cabane struts in a similar way. This strongly suggests that any forceon the cabane attach points will be taken up by the struts long before thestiffness of the wing itself becomes a factor, and that attach pointstresses should be nearly identical between one and three-piece wings.I totally agree with your other comments though, that the bottom of thefuselage is always in tension, and that force on the cabanes, whethertension or compression, is minimal.Gene HubbardSan Diego________________________________________________________________________________
Chris,I don't see that the one-piece wing can possibly be stiff enough to affectthe cabane and lift strut loading ratios. My reasoning is that I have nodoubt that I could, with hand pressure, flex the one-piece wing with thecabane struts removed such that the distance between atatch points changesmeasurably. This is really a crude way of establishing a Young's modulus ofmaybe a few hundred to a thousand pounds per inch of displacement.Similarly, I cannot imagine, under any circumstances, changing the length ofthe cabane struts in a similar way. This strongly suggests that any forceon the cabane attach points will be taken up by the struts long before thestiffness of the wing itself becomes a factor, and that attach pointstresses should be nearly identical between one and three-piece wings.I totally agree with your other comments though, that the bottom of thefuselage is always in tension, and that force on the cabanes, whethertension or compression, is minimal.Gene HubbardSan Diego________________________________________________________________________________
RE: Pietenpol-List: Landing gear reinforcement straps
Original Posted By: owner-pietenpol-list-server(at)matronics.com
Gene,The mechanical engineers say here on the piet list that the one piece wingreally does not need the cabanes at all except to stabilize the wing whenthe spars are in compression much like the jury struts stablize the wingstruts. The wing area outboard of the wing struts is equal to the areainboard so the up lift outboard causes the inboard to deflect down but thisis countered by the inboard lift force up which is countered by....well youknow the rest.Look at the wing as a column. If you pull G's, then the straps are tryingto move closer to the cabane/wing joint, putting the fuselage sides and thecabanes in compression. Obviously with the increased G's, the wing islifting that much harder and the fuselage weight is pulling down away fromthe cabane/wing joint. The wing strut attach points at the wing are tryingto move toward one another putting the wing spars between the wing strutattach fittings, wing to wing, in compression. The wing section is fairlythin and the 20:1 max slenderness ratio rule comes into play. The sparsbecome axially loaded columns with a deflection.Think of your leg in a cast vs. having a flexible knee joint. A column witha pinned joint half way along its length has to behave substantiallydifferent from a solid column with no joint, especially when it is beingdeflected.The pinned joint on the multiple piece wing changes things, right?Amateur engineer still learning,chris bobka-----Original Message-----
Gene,The mechanical engineers say here on the piet list that the one piece wingreally does not need the cabanes at all except to stabilize the wing whenthe spars are in compression much like the jury struts stablize the wingstruts. The wing area outboard of the wing struts is equal to the areainboard so the up lift outboard causes the inboard to deflect down but thisis countered by the inboard lift force up which is countered by....well youknow the rest.Look at the wing as a column. If you pull G's, then the straps are tryingto move closer to the cabane/wing joint, putting the fuselage sides and thecabanes in compression. Obviously with the increased G's, the wing islifting that much harder and the fuselage weight is pulling down away fromthe cabane/wing joint. The wing strut attach points at the wing are tryingto move toward one another putting the wing spars between the wing strutattach fittings, wing to wing, in compression. The wing section is fairlythin and the 20:1 max slenderness ratio rule comes into play. The sparsbecome axially loaded columns with a deflection.Think of your leg in a cast vs. having a flexible knee joint. A column witha pinned joint half way along its length has to behave substantiallydifferent from a solid column with no joint, especially when it is beingdeflected.The pinned joint on the multiple piece wing changes things, right?Amateur engineer still learning,chris bobka-----Original Message-----
Re: Pietenpol-List: Landing gear reinforcement straps
Original Posted By: Christian Bobka
I won't get into the total of the conversation, but the cabane struts arerequired for more than is suggested here. The "roll wires" which keep thetop wing from moving left and right in relation to the fuselage must havesomething to pull against, i.e. the cabanes.Gene Rambo----- Original Message -----
I won't get into the total of the conversation, but the cabane struts arerequired for more than is suggested here. The "roll wires" which keep thetop wing from moving left and right in relation to the fuselage must havesomething to pull against, i.e. the cabanes.Gene Rambo----- Original Message -----
> RE: Pietenpol-List: Landing gear reinforcement straps
Original Posted By: clif
> RE: Pietenpol-List: Landing gear reinforcement straps
Original Posted By: Michael D Cuy
RE: Pietenpol-List: Landing gear reinforcement straps
Original Posted By: clif [mailto:cdawson5854(at)shaw.ca]
Clif,I found your entry on mykitplane.com, but didn't find your chart. I willagree that taking a (nominally) elliptical lift profile into account, theinner half of the wing will be providing more lift than the outer half.Doing the math, I get about 61% if the lift struts attach exactly half wayfrom the cabanes to the wingtips. This assumes that the center sectiondoesn't do anything in particular, probably a good assumption if you have acutout or a radiator.Assuming that the wing pivots about the lift struts, this puts about 22% ofthe total load on the cabanes, or around 110 lb on each side at 1000 lbgross. Pick your favorite load ratio between front and rear spars, butwe're still not talking large loads here.Gene-----Original Message-----
Clif,I found your entry on mykitplane.com, but didn't find your chart. I willagree that taking a (nominally) elliptical lift profile into account, theinner half of the wing will be providing more lift than the outer half.Doing the math, I get about 61% if the lift struts attach exactly half wayfrom the cabanes to the wingtips. This assumes that the center sectiondoesn't do anything in particular, probably a good assumption if you have acutout or a radiator.Assuming that the wing pivots about the lift struts, this puts about 22% ofthe total load on the cabanes, or around 110 lb on each side at 1000 lbgross. Pick your favorite load ratio between front and rear spars, butwe're still not talking large loads here.Gene-----Original Message-----
RE: Pietenpol-List: Landing gear reinforcement straps
Original Posted By: "The Huizenga's"