---------------------------------------------------------- Lightning-List Digest Archive --- Total Messages Posted Wed 09/12/12: 5 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:27 AM - Re: Lightning Newsletter Booklets (Caithness Manor) 2. 07:09 AM - Landing Gear and shimmy (Nick Otterback) 3. 07:19 AM - Re: Landing Gear and shimmy (Dennis W. Wilt) 4. 09:04 AM - Re: Landing Gear and shimmy (Nick Otterback) 5. 10:31 AM - Re: Landing Gear and shimmy (Dennis W. Wilt) ________________________________ Message 1 _____________________________________ Time: 05:27:58 AM PST US Subject: Lightning-List: Re: Lightning Newsletter Booklets From: "Caithness Manor" I'll do some research Buz and let you know. Cheers. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=382915#382915 ________________________________ Message 2 _____________________________________ Time: 07:09:27 AM PST US From: "Nick Otterback" Subject: Lightning-List: Landing Gear and shimmy The original esqual gear was a flat plate steel type which bolted to the fuselage thru the 6 bolts holding the spar box in. the overturn angle of the gear (how much it angled from the fuselage) was very steep. This transfers more load to the attach points and surrounding structure because it wont flex as much. The EXP tube gear has greater angle and less load transfer but is more subject to shimmy being a round rod. The Lightning EXP gear is 7075T6, plenty sturdy for the intended application. The Equal round gear is a different type alloy, although I do not remember what, experience in the field says it=92s something lighter in alloy than the 7075T6. A spring steel gear is not necessarily stronger than aluminum. The RV are spring steel an too subject to shimmy, I have experienced in a few of the RV models I have flown. IT is just a matter of a round tube subject to it. The Steel has a higher frequency and may not exhibit a shimmy at the same speed and aircraft weight of the aluminum. I have even experienced in a Rans S7S with round tube gear, just at a lower speed around 12-15mph on roll out. What we have found works here, covered multiple times. Is about 1 degree toe out on the EXP gear. This coupled with air-pressure in the 22-25psi range with keep drag on the gear and minimize it from moving around . Higher air-pressure just causes the tire to skip and shimmy better. Also it seems that the Better tires help, I believe from the squared off tire tread they have instead of the round tread. If all of this does not help we have almost completely eliminated it on aircraft when bonding hardwood to the gear leg. Simply clamping the hard wood to the Leg will not help. I have used wood like Oak. A piece of hard wood that it fitted to within =BC=94 of the bottom of the fuselage to the lower socket. Mill out one side =BD round to fit the gear leg. The wood should be at least the 1=94 wide that the gear is, by about 2=94 aft of it. Mill the trailing edge to fit under the leg fairing. Lightly sand the aft side of the gear leg. Bond the gear leg to the back of the gear leg with 24hr epoxy and flox, clamp in place to cure. After cure wrap the wood and leg with 10oz glass. The glass should be cut in sections the same length as the hard wood by about 7=94 wide to completely wrap the gear. Also it is critical to cut these sections out of the glass cloth on a 45 degree bias to the weave. IF you simply use the glass in the direction of the weave it will not resist the fore and aft movement of the gear. I have use about 4 layers of glass. I suppose if you wished 2 layers of carbon cut a laminated the same way should work. The wood does stiffen the gear, but keeps the spring it needs, What the wood does is change the frequency that the gear shimmy=92s at and helps dampen out any that may occur. Lighter or softer materials will not work. Simply adding glass to the gear will not help. As for the LSA wide track landing gear. We set the gear at 0 toe, straight ahead, with the wings off the aircraft. Actually we set this with the spar box out of the aircraft during the build process. With a little weight on the gear it may toe out slightly. We very rarely run into shimmy with the big gear, if we do it usually goes back to over inflated tires, flat spots, or infrequent flying that flat spots the tires and creates a skip. The overturn angle of the LSA gear is much greater than the EXP gear. The LSA gear is 2.125=94 at the top and 1.25=94 at the bottom VS 1.375=94 and 1=94 on the EXP gear just for FYI. Nick Otterback Arion Aircraft LLC R&D Technical Support 931-680-1781 nick@flylightning.net ________________________________ Message 3 _____________________________________ Time: 07:19:02 AM PST US Subject: Re: Lightning-List: Landing Gear and shimmy From: "Dennis W. Wilt" My EA-B version of the LSA has the LSA gear just because they are supposed to be a bit more sturdy. My only complaint with the lightning gear is that it is not very forgiving on landing. It is pretty stiff, so if you happen to land a little hard, you will bounce and that means a go around for me. Some of you may be better at saving such a landing, but I choose to go aro und and do it again, hopefully without the bounce. I set my toe to 0 degrees without weight on the wheels and keep my air pres sure around 25 psi. I have never had the shimmy. Have a wonderful day, Dennis N616DW (Arion Lightning S/N 132) -----Original Message----- From: Nick Otterback Sent: Wed, Sep 12, 2012 10:09 am Subject: Lightning-List: Landing Gear and shimmy The original esqual gear was a flat plate steel type which bolted to the fu selage thru the 6 bolts holding the spar box in. the overturn angle of the gear (how much it angled from the fuselage) was very steep. This transfers more load to the attach points and surrounding structure because it wont fl ex as much. The EXP tube gear has greater angle and less load transfer but is more subject to shimmy being a round rod. The Lightning EXP gear is 7075 T6, plenty sturdy for the intended application. The Equal round gear is a d ifferent type alloy, although I do not remember what, experience in the fie ld says it=99s something lighter in alloy than the 7075T6. A spring steel gear is not necessarily stronger than aluminum. The RV are s pring steel an too subject to shimmy, I have experienced in a few of the R V models I have flown. IT is just a matter of a round tube subject to it. T he Steel has a higher frequency and may not exhibit a shimmy at the same sp eed and aircraft weight of the aluminum. I have even experienced in a Rans S7S with round tube gear, just at a lower speed around 12-15mph on roll out . What we have found works here, covered multiple times. Is about 1 degree to e out on the EXP gear. This coupled with air-pressure in the 22-25psi range with keep drag on the gear and minimize it from moving around . Higher air -pressure just causes the tire to skip and shimmy better. Also it seems tha t the Better tires help, I believe from the squared off tire tread they hav e instead of the round tread. If all of this does not help we have almost completely eliminated it on air craft when bonding hardwood to the gear leg. Simply clamping the hard wood to the Leg will not help. I have used wood like Oak. A piece of hard wood t hat it fitted to within =C2=BC=9D of the bottom of the fuselage to th e lower socket. Mill out one side =C2=BD round to fit the gear leg. The woo d should be at least the 1=9D wide that the gear is, by about 2 =9D aft of it. Mill the trailing edge to fit under the leg fairing. Lightly sand the aft side of the gear leg. Bond the gear leg to the back of the ge ar leg with 24hr epoxy and flox, clamp in place to cure. After cure wrap th e wood and leg with 10oz glass. The glass should be cut in sections the sam e length as the hard wood by about 7=9D wide to completely wrap the g ear. Also it is critical to cut these sections out of the glass cloth on a 45 degree bias to the weave. IF you simply use the glass in the direction o f the weave it will not resist the fore and aft movement of the gear. I hav e use about 4 layers of glass. I suppose if you wished 2 layers of carbon c ut a laminated the same way should work. The wood does stiffen the gear, but keeps the spring it needs, What the woo d does is change the frequency that the gear shimmy=99s at and helps dampen out any that may occur. Lighter or softer materials will not work. S imply adding glass to the gear will not help. As for the LSA wide track landing gear. We set the gear at 0 toe, straight ahead, with the wings off the aircraft. Actually we set this with the spar box out of the aircraft during the build process. With a little weight on t he gear it may toe out slightly. We very rarely run into shimmy with the bi g gear, if we do it usually goes back to over inflated tires, flat spots, o r infrequent flying that flat spots the tires and creates a skip. The overt urn angle of the LSA gear is much greater than the EXP gear. The LSA gear i s 2.125=9D at the top and 1.25=9D at the bottom VS 1.375 =9D and 1=9D on the EXP gear just for FYI. Nick Otterback Arion Aircraft LLC R&D Technical Support 931-680-1781 nick@flylightning.net ________________________________ Message 4 _____________________________________ Time: 09:04:36 AM PST US From: "Nick Otterback" Subject: RE: Lightning-List: Landing Gear and shimmy I think you might mean springy not stiff. During drop test at gross weight, we have nearly 6=9D deflection of the landing gear system. The little tube in a tube is an easy way to check deflection, set against the ground before the drop and see how far it gets displaced. Usually the bounce comes from the nose gear return and the aircraft going back into a flight attitude with sufficient speed to fly. Attached some pics for fun. The drop test were the funnest testing we did, along with destructive testing of the wing. Nick From: owner-lightning-list-server@matronics.com [mailto:owner-lightning-list-server@matronics.com] On Behalf Of Dennis W. Wilt Sent: Wednesday, September 12, 2012 9:18 AM Subject: Re: Lightning-List: Landing Gear and shimmy My EA-B version of the LSA has the LSA gear just because they are supposed to be a bit more sturdy. My only complaint with the lightning gear is that it is not very forgiving on landing. It is pretty stiff, so if you happen to land a little hard, you will bounce and that means a go around for me. Some of you may be better at saving such a landing, but I choose to go around and do it again, hopefully without the bounce. I set my toe to 0 degrees without weight on the wheels and keep my air pressure around 25 psi. I have never had the shimmy. Have a wonderful day, Dennis N616DW (Arion Lightning S/N 132) -----Original Message----- From: Nick Otterback Sent: Wed, Sep 12, 2012 10:09 am Subject: Lightning-List: Landing Gear and shimmy The original esqual gear was a flat plate steel type which bolted to the fuselage thru the 6 bolts holding the spar box in. the overturn angle of the gear (how much it angled from the fuselage) was very steep. This transfers more load to the attach points and surrounding structure because it wont flex as much. The EXP tube gear has greater angle and less load transfer but is more subject to shimmy being a round rod. The Lightning EXP gear is 7075T6, plenty sturdy for the intended application. The Equal round gear is a different type alloy, although I do not remember what, experience in the field says it=99s something lighter in alloy than the 7075T6. A spring steel gear is not necessarily stronger than aluminum. The RV are spring steel an too subject to shimmy, I have experienced in a few of the RV models I have flown. IT is just a matter of a round tube subject to it. The Steel has a higher frequency and may not exhibit a shimmy at the same speed and aircraft weight of the aluminum. I have even experienced in a Rans S7S with round tube gear, just at a lower speed around 12-15mph on roll out. What we have found works here, covered multiple times. Is about 1 degree toe out on the EXP gear. This coupled with air-pressure in the 22-25psi range with keep drag on the gear and minimize it from moving around . Higher air-pressure just causes the tire to skip and shimmy better. Also it seems that the Better tires help, I believe from the squared off tire tread they have instead of the round tread. If all of this does not help we have almost completely eliminated it on aircraft when bonding hardwood to the gear leg. Simply clamping the hard wood to the Leg will not help. I have used wood like Oak. A piece of hard wood that it fitted to within =C2=BC=9D of the bottom of the fuselage to the lower socket. Mill out one side =C2=BD round to fit the gear leg. The wood should be at least the 1=9D wide that the gear is, by about 2=9D aft of it. Mill the trailing edge to fit under the leg fairing. Lightly sand the aft side of the gear leg. Bond the gear leg to the back of the gear leg with 24hr epoxy and flox, clamp in place to cure. After cure wrap the wood and leg with 10oz glass. The glass should be cut in sections the same length as the hard wood by about 7=9D wide to completely wrap the gear. Also it is critical to cut these sections out of the glass cloth on a 45 degree bias to the weave. IF you simply use the glass in the direction of the weave it will not resist the fore and aft movement of the gear. I have use about 4 layers of glass. I suppose if you wished 2 layers of carbon cut a laminated the same way should work. The wood does stiffen the gear, but keeps the spring it needs, What the wood does is change the frequency that the gear shimmy=99s at and helps dampen out any that may occur. Lighter or softer materials will not work. Simply adding glass to the gear will not help. As for the LSA wide track landing gear. We set the gear at 0 toe, straight ahead, with the wings off the aircraft. Actually we set this with the spar box out of the aircraft during the build process. With a little weight on the gear it may toe out slightly. We very rarely run into shimmy with the big gear, if we do it usually goes back to over inflated tires, flat spots, or infrequent flying that flat spots the tires and creates a skip. The overturn angle of the LSA gear is much greater than the EXP gear. The LSA gear is 2.125=9D at the top and 1.25=9D at the bottom VS 1.375=9D and 1=9D on the EXP gear just for FYI. Nick Otterback Arion Aircraft LLC R&D Technical Support 931-680-1781 nick@flylightning.net " target="_blank" saprocessedanchor="true">http://www.matronics.com/Navigator?Lightning-L ist processedanchor="true">http://forums.matronics.com _blank" saprocessedanchor="true">http://www.matronics.com/contribution ________________________________ Message 5 _____________________________________ Time: 10:31:54 AM PST US Subject: Re: Lightning-List: Landing Gear and shimmy From: "Dennis W. Wilt" Nick, could be, but I know of at least 2 that was a bounce off the mains. Cool pictures, I would like to see video. Have a wonderful day, Dennis N616DW (Arion Lightning S/N 132) -----Original Message----- From: Nick Otterback Sent: Wed, Sep 12, 2012 12:07 pm Subject: RE: Lightning-List: Landing Gear and shimmy I think you might mean springy not stiff. During drop test at gross weight, we have nearly 6=9D deflection of the landing gear system. The littl e tube in a tube is an easy way to check deflection, set against the ground before the drop and see how far it gets displaced. Usually the bounce come s from the nose gear return and the aircraft going back into a flight attit ude with sufficient speed to fly. Attached some pics for fun. The drop test were the funnest testing we did, along with destructive testing of the wing. Nick From: owner-lightning-list-server@matronics.com [mailto:owner-lightning-lis t-server@matronics.com] On Behalf Of Dennis W. Wilt Sent: Wednesday, September 12, 2012 9:18 AM Subject: Re: Lightning-List: Landing Gear and shimmy My EA-B version of the LSA has the LSA gear just because they are supposed to be a bit more sturdy. My only complaint with the lightning gear is that it is not very forgiving on landing. It is pretty stiff, so if you happen to land a little hard, you will bounce and that means a go around for me. Some of you may be better at saving such a landing, but I choose to go aro und and do it again, hopefully without the bounce. I set my toe to 0 degrees without weight on the wheels and keep my air pres sure around 25 psi. I have never had the shimmy. Have a wonderful day, Dennis N616DW (Arion Lightning S/N 132) -----Original Message----- From: Nick Otterback Sent: Wed, Sep 12, 2012 10:09 am Subject: Lightning-List: Landing Gear and shimmy The original esqual gear was a flat plate steel type which bolted to the fu selage thru the 6 bolts holding the spar box in. the overturn angle of the gear (how much it angled from the fuselage) was very steep. This transfers more load to the attach points and surrounding structure because it wont fl ex as much. The EXP tube gear has greater angle and less load transfer but is more subject to shimmy being a round rod. The Lightning EXP gear is 7075 T6, plenty sturdy for the intended application. The Equal round gear is a d ifferent type alloy, although I do not remember what, experience in the fie ld says it=99s something lighter in alloy than the 7075T6. A spring steel gear is not necessarily stronger than aluminum. The RV are s pring steel an too subject to shimmy, I have experienced in a few of the R V models I have flown. IT is just a matter of a round tube subject to it. T he Steel has a higher frequency and may not exhibit a shimmy at the same sp eed and aircraft weight of the aluminum. I have even experienced in a Rans S7S with round tube gear, just at a lower speed around 12-15mph on roll out . What we have found works here, covered multiple times. Is about 1 degree to e out on the EXP gear. This coupled with air-pressure in the 22-25psi range with keep drag on the gear and minimize it from moving around . Higher air -pressure just causes the tire to skip and shimmy better. Also it seems tha t the Better tires help, I believe from the squared off tire tread they hav e instead of the round tread. If all of this does not help we have almost completely eliminated it on air craft when bonding hardwood to the gear leg. Simply clamping the hard wood to the Leg will not help. I have used wood like Oak. A piece of hard wood t hat it fitted to within =C2=BC=9D of the bottom of the fuselage to th e lower socket. Mill out one side =C2=BD round to fit the gear leg. The woo d should be at least the 1=9D wide that the gear is, by about 2 =9D aft of it. Mill the trailing edge to fit under the leg fairing. Lightly sand the aft side of the gear leg. Bond the gear leg to the back of the ge ar leg with 24hr epoxy and flox, clamp in place to cure. After cure wrap th e wood and leg with 10oz glass. The glass should be cut in sections the sam e length as the hard wood by about 7=9D wide to completely wrap the g ear. Also it is critical to cut these sections out of the glass cloth on a 45 degree bias to the weave. IF you simply use the glass in the direction o f the weave it will not resist the fore and aft movement of the gear. I hav e use about 4 layers of glass. I suppose if you wished 2 layers of carbon c ut a laminated the same way should work. The wood does stiffen the gear, but keeps the spring it needs, What the woo d does is change the frequency that the gear shimmy=99s at and helps dampen out any that may occur. Lighter or softer materials will not work. S imply adding glass to the gear will not help. As for the LSA wide track landing gear. We set the gear at 0 toe, straight ahead, with the wings off the aircraft. Actually we set this with the spar box out of the aircraft during the build process. With a little weight on t he gear it may toe out slightly. We very rarely run into shimmy with the bi g gear, if we do it usually goes back to over inflated tires, flat spots, o r infrequent flying that flat spots the tires and creates a skip. The overt urn angle of the LSA gear is much greater than the EXP gear. The LSA gear i s 2.125=9D at the top and 1.25=9D at the bottom VS 1.375 =9D and 1=9D on the EXP gear just for FYI. Nick Otterback Arion Aircraft LLC R&D Technical Support 931-680-1781 nick@flylightning.net " target="_blank" saprocessedanchor="true">http://www.matronics.com/Nav igator?Lightning-List processedanchor="true">http://forums.matronics.com _blank" saprocessedanchor="true">http://www.matronics.com/contribution http://www.matronics.com/Navigator?Lightning-List http://forums.matronics.com http://www.matronics.com/contribution ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message lightning-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Lightning-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/lightning-list Browse Digests http://www.matronics.com/digest/lightning-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.