SR X250 saga
02-17-2014, 10:23 AM
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SR Batteries X250 saga
http://www.srbatteries.com/x250.htm
The power system from SR, a geared speed 400 using their 500Max 10 cell NiCad battery and a Graupner 9X5 Slim Prop pack was very good for it's day in comparison to other brushed airplane of the time. The packs cost $75.00 bucks apiece and I bought three when the plane kit. The maiden was a dream, the frame flew perfect. But the second flight resulted in a minor crash. I figured RF problems. The repair was minor and soon had it in the air only to plagued intermittently with a power loss a couple of minutes into flight. I swapped out ESC's and Rx's only to think I had the problem resolved long enough to have another crash. Well the day came when it lost power on a breezy day during take off with no room to recover from the stall. That crash resulted in what is left on the bench. I finally discovered what was wrong after the purchase of a CBA from West Mountain radio. When the packs were cycled on a average charger/ discharger the end discharge number, say 480mAh would one would assume that the battery was up to snuff, that changed when I graphed the discharge of #3 pack. The discharge at 5A would run about 2min. and then the V would drop to less than 2V for a couple of seconds and then return to normal and discharge close to spec. Zowie! as anyone ever heard of a battery behaving in such a fashion? This test was 100% repeatable . I never noticed that pack 3 was the one that always resulted in power loss and sometimes a crash.
So my lesson here is expensive and new does not make it good. Good news is I get to rebuild it and incorporate a few changes. First I want to add a steerable nose wheel. Second I'm going to up date the power system to BL Lipo. The original single aileron servo with mechanical differential didn't work well for me so I had already modified the wing for duel aileron servos.
The kit comes with a nice set of planes so all I had to do was cut out new parts. But feeling like experimenting I decided to make a hybrid fuselage, using Dollar Tree $1.00 foam board, some balsa and CF rods.
Last edited by zeroback; 02-19-2014 at 12:57 PM. Reason: adding content
02-17-2014, 03:45 PM
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This tail section is my starter kit. OK now that I have the photo thing worked out I can get on with the modification and repair.
Last edited by zeroback; 02-17-2014 at 03:48 PM.
02-18-2014, 02:59 PM
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The motor is an Aeolian C3530 Kv1100. The motor weighs 73g and a no load test showed a 1167Kv on 3S @ 1.4A.
Swinging the 9X5 Slim Prop the set pulled 15.3A @ 11.54V 9514RPM. I recall static thrust measured around 24oz.
I'll be using a 20ATurnigy Super Brain ESC to record in flight data. With the supplied inflight data I'll rewind the motor to maximize efficiency.
Dubros nifty 1/2 steerable nose wheel looks like it fits the bill.
02-19-2014, 11:41 AM
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Some more work done. I have the plastic gear version of the micro servo, I'll find out if the floating on foam mounting keeps the gear from braking. The only reverser I have on hand also has a slowing feature that may come in handy for taxying purposes. I'm also using some neoprene washers to hopefully keep the motor from harmonizing with the plywood box. I have a ZoomZoom that really has a whine to it. That mount amplifies an otherwise quite dLRK 2212 motor to a frequency that cause's people to ask if the motor is OK. Ick.
I'm also looking to keep the AUW to 20oz versus the OEM 24oz. One of the reasons I'm working this project is to have an aileron trainer on hand after the Blu-Baby ihttp://www.rcgroups.com/forums/showthread.php?t=1277127s mastered for locals who want to learn how to fly. Counterintuitive to the overhead wing aileron trainer this fly's better than any other trainer of that nature.
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I'm also looking to keep the AUW to 20oz versus the OEM 24oz. One of the reasons I'm working this project is to have an aileron trainer on hand after the Blu-Baby ihttp://www.rcgroups.com/forums/showthread.php?t=1277127s mastered for locals who want to learn how to fly. Counterintuitive to the overhead wing aileron trainer this fly's better than any other trainer of that nature.
.
02-22-2014, 07:01 PM
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some mo progress
2) Rudder and elevator are being handled by GS-5 Gravity digital servo scavenged from a 32" Edge never heard of the brand but that's what the LHS carried. With the amount of backlash in the gear set I don't think the digital feature is of much use. But they seem to be tough as having survived the evolution of the Edge from EPP into Welders Glue.
1) JCX-M6 gyro I've been wanting to try this little gizmo in something and here is a good opportunity to see how these perform. It may save me some wing tip repairs when a beginner is on the sticks as my run way usually always has a cross wind. And on many days the light and variable is very light and variable. And the runway is seashell and tar sorta like 00000 grit sand paper. A fellow who uses the same runway in the Everglades erased half a HK foamy jet when his LG collapsed .
1) HK 20A Superbrain ESC along with the Turnigy Servo reverser/slower. I plan to experiment to see if the slower can be used to dampen the steering to improve handling.
I ordered a couple oy short Y harness only to find out after installing them they didn't work, Heads up is sending some replacements but for now I have used some oversized leads to get it going for now. Next I have to come up with a way to cover up the guts. In order to get all this gear and a 1350 TP 3S I did some creative solder joints. No room for those bulky bullet plugs. But a fancy shaker scoop may be in order. I have gecko's in my shop (come with the territory) so I have a scare lizard to keep em off the project. They seem to enjoy leaving me undesired presents in the most sensitive places.
1) 2.4 Spektrum compatible 6 channel allowing switching the gyro off and on. So far I have had good luck with all of the budget based brands of compatible Rx's.
2) Rudder and elevator are being handled by GS-5 Gravity digital servo scavenged from a 32" Edge never heard of the brand but that's what the LHS carried. With the amount of backlash in the gear set I don't think the digital feature is of much use. But they seem to be tough as having survived the evolution of the Edge from EPP into Welders Glue.
1) JCX-M6 gyro I've been wanting to try this little gizmo in something and here is a good opportunity to see how these perform. It may save me some wing tip repairs when a beginner is on the sticks as my run way usually always has a cross wind. And on many days the light and variable is very light and variable. And the runway is seashell and tar sorta like 00000 grit sand paper. A fellow who uses the same runway in the Everglades erased half a HK foamy jet when his LG collapsed .
1) HK 20A Superbrain ESC along with the Turnigy Servo reverser/slower. I plan to experiment to see if the slower can be used to dampen the steering to improve handling.
I ordered a couple oy short Y harness only to find out after installing them they didn't work, Heads up is sending some replacements but for now I have used some oversized leads to get it going for now. Next I have to come up with a way to cover up the guts. In order to get all this gear and a 1350 TP 3S I did some creative solder joints. No room for those bulky bullet plugs. But a fancy shaker scoop may be in order. I have gecko's in my shop (come with the territory) so I have a scare lizard to keep em off the project. They seem to enjoy leaving me undesired presents in the most sensitive places.
1) 2.4 Spektrum compatible 6 channel allowing switching the gyro off and on. So far I have had good luck with all of the budget based brands of compatible Rx's.
Last edited by zeroback; 02-27-2014 at 04:21 PM. Reason: SP
02-27-2014, 04:26 PM
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Off the side of the Midnight Express they are painted on. My buddy was building the boat and I was visiting him for lunch, so I snapped a few pics. I didn't organize my photos in those days so when I found pics of the original build I the Midnight photos happened to be right there.
06-04-2014, 02:09 PM
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I was also thinking of explaining the long bulbous nose as a scale model of a plane that never existed, utilizing a vertical flat 26 cylinder inline two stroke diesel submarine engine for power. Problem is I only have 18 exhaust pipes left over from a scale radial kit I put in my Bearcat.
06-05-2014, 08:26 AM
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I have a brand new X250 kit (bought ten years ago) just now on the building board. I plan twin brushless motors and tricycle retracts for use as an advanced trainer. Now that you mentioned lighting that I'll have to add them as well much easier to plan them into the build than add on later.
Last edited by zeroback; 06-05-2014 at 08:30 AM.
06-06-2014, 08:19 AM
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With my luck I would be sued for copyright infringement.
I do believe I qualify to be a charter member of the Builds Slower than a Dead Turtle Nailed to a Fence Post Association. Although being a member of PETA (People Eating Tasty Animals) I would have to make sure that turtle was made into soup first!
I do believe I qualify to be a charter member of the Builds Slower than a Dead Turtle Nailed to a Fence Post Association. Although being a member of PETA (People Eating Tasty Animals) I would have to make sure that turtle was made into soup first!
06-06-2014, 08:59 AM
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With my luck I would be sued for copyright infringement.
I do believe I qualify to be a charter member of the Builds Slower than a Dead Turtle Nailed to a Fence Post Association. Although being a member of PETA (People Eating Tasty Animals) I would have to make sure that turtle was made into soup first!
I do believe I qualify to be a charter member of the Builds Slower than a Dead Turtle Nailed to a Fence Post Association. Although being a member of PETA (People Eating Tasty Animals) I would have to make sure that turtle was made into soup first!
06-07-2014, 10:36 AM
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Adding a wind screen and a bit of cockpit detail, certainly adds to the 26 cyl vertical flat two stroke submarine diesel theme. Although I find it is still lacking something.
06-08-2014, 06:03 PM
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Couldn't find the cowbell so I settled for lightning bolts and arrows. Couldn't find my videographer for the taxi test so I took some pics. Sorta looks British... Oh well that's what happens when covering with scrap and no plan. I think I'm going to give an 8X6X3 as the 9X6 is whacking the ground when I hit small bumps in the road. I didn't mind tearing up the $.99 MA prop but those Slim Props are close to $10.00 apiece now days. The other issue with the Slim prop is the 8mm prop shaft hole the adaptor from the original power set up is unnecessarily heavy. 4mm to 8mm is an odd ball adaptor and will require taller wheels to run a 9" prop
06-10-2014, 03:52 PM
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I don't know what happened to my last post with a link to the video of the taxi test. I'll have try it again.
http://youtu.be/aBEfY4BrXr0
Well lets see if this link sticks
My isolation motor mounts worked. My planes with motors mounted directly to the fire wall are typically very noisy due to some harmonizing effect from the wood , like a guitar box amplifies the sound of the strings when plucked. Picked up a few different props from the LHS, including an Master Airscrew 8X6X3, should be interesting to see which prop performs the best. I'm betting the APC 9X6E will out shine the Graupner and the Master Airscrew. That has been my experience so far that no one does a prop like APC. Although the 3 blade looks good on the plane the data usually shows what power wasters they are.
http://youtu.be/aBEfY4BrXr0
Well lets see if this link sticks
My isolation motor mounts worked. My planes with motors mounted directly to the fire wall are typically very noisy due to some harmonizing effect from the wood , like a guitar box amplifies the sound of the strings when plucked. Picked up a few different props from the LHS, including an Master Airscrew 8X6X3, should be interesting to see which prop performs the best. I'm betting the APC 9X6E will out shine the Graupner and the Master Airscrew. That has been my experience so far that no one does a prop like APC. Although the 3 blade looks good on the plane the data usually shows what power wasters they are.
Last edited by zeroback; 06-11-2014 at 08:42 AM.