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| The Storch has Finally flown all 50 Seconds of it ! | |
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| Topic Started: Jul 24 2017, 10:05 AM (399 Views) | |
| Stuart | Jul 24 2017, 10:05 AM Post #1 |
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Administrator
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Flew the Storch at the Wealden at their Berwick Flying Site. As you can see it was very sort with some damage on landing but could have been a lot worse. Post flight review: Woefully under powered struggled to get air bourne. Thinking about it on the way home the Laser 100 power train only just about flew the Cloud hopper and as the Storch is almost the same weight then I should not be surprised at the lack of power. The under carriage is not up to the job this has been a concern all along as its only ally tube. CG needs to be moved forward as it seems to be tail heavy. Pilot needs to lessons on how to land !! The power I think I can resolve by installing a Laser 150 as its should fit in without much modification. Carbon fiber tube epoxied inside the ally tubes landing legs. The CG issue should be resolved with the bigger motor but I'm sure this will put the model over 7KG which will mean it wont fly at the club field. I may be able to remove some weigh by making the pilot lighter by removing the servos that make his head move etc and making a material covered wire frame for his body. But doubt if this will be sufficient to bring it under 7KG. Big thanks to Bob Hart for his help and the Wealden club. (you may be getting a new member) Video of flight Wing route needs repairing. ![]() Bent U/C ![]() |
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| ChrisS | Jul 24 2017, 11:57 AM Post #2 |
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A good approach and had the undercarriage been a bit stronger it would probably just have bounced a bit. The very first landing of a model is always going to be an unknown quantity. |
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| ChrisS | Jul 24 2017, 07:03 PM Post #3 |
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Thinking about the lack of power; Are you using 10% nitro fuel (I believe Laser engines Ltd don't recommend it). Maybe try a finer pitched prop. Use a tachometer to ensure maximum revs are being reached. Try and lighten the aircraft. |
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| Max Woodhead | Jul 24 2017, 08:12 PM Post #4 |
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I would go the lighten the ship route first but do not know what scope you have. Heavier more powerful engine would give you an inappropriately fast Storch and stress the landing gear even more. Maybe replace the landing gear temporarily with a piano wire rig eg Puppetteer. Have you got the plan, Svenson was it not ? What is the wing loading ? Are you sure about the CG where is it referenced to percent of chord ? Pendulum method will give you a very precise measurement. Have you checked incidence of main and tailplanes ? I looked around for the Svenson specs but did not find much, originally quoted for a .60 2s, par engine for the 70's, could not find the expected flying weight. Did you use any flap for t/o and landing ? |
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| Max Woodhead | Jul 24 2017, 08:56 PM Post #5 |
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A few videos on youtube of Svenson Storch flying ok only saw two that reported AUW which were in the 5-6 kg range. |
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| Mike Lippert | Jul 25 2017, 11:37 AM Post #6 |
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Aww bad luck Stuart after all that effort well done for getting it round on the strip again it was gutless. |
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| Stuart | Jul 25 2017, 02:41 PM Post #7 |
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Administrator
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Off Sick at the moment with a streaming cold so information as I recall it (must be ill not down the shed) Chris I'm using a graupner gray 15x 6 prop and 8700 rpm I think. From the laser website Recommended full power RPM range 7500-9000 Recommended props 14×7-8 15×6-8 16×6 I ran the motor up last Friday and it seemed to be on song but did not taco it. I have always used 10% nitro I thought it gave better starting and running but happy to be corrected by those in the know. I thought Neal ran his on 10%. Max. Yes its a Svenson kit and have whats left of the plans and the instruction booklet what there is of it. The CG is as marked on the plan but there are no measurements so I had measure it on the plan from the front bulkhead. Incidence of the Wing and tail section was set when i built it and rechecked after I covered it +2.5 on the wing and 0 on the tail i will recheck it. I did not use any flaps at take off or landing the theory was to get some height and deploy the flaps to see of there was any change in pitch but I did not get that far. I have an old Jan 1982 RCM&E that Chris gave/lent me that has a wright up on the model with some suggested control throws but not a lot else. the model they tested had a AUW of 5.9KG so mine at almost 7kg is well fat. I did remove the pilot and he weighs in at 300 grams so I could save some there by making him lighter but cant see where else I can save weight smaller lighter servos may help but not easy to get to them in the Fuz. The Wing ones I can get to. U/C I'm reviewing if I make it to strong and have a hard landing it may rip out the U/C mount point in the Fuz and that's major surgery to get to them. I have a Laser 150 that I'm putting in the DR1. I could install it as its almost the same size and use a fine pitch prop to cut down on the speed but up the grunt. Recommended props 16×6-10 17×6-8 18×6-8 Thanks for your comments and suggestions. ![]() Edited by Stuart, Jul 25 2017, 02:43 PM.
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| Max Woodhead | Jul 25 2017, 03:25 PM Post #8 |
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Ok so you need to lose at least a kilo and Fritz is one third of that so a great start. Be ruthless you can always put non-essentials back later. I saved 6-7 oz on the Lizzie just by changing the main wheels. Still don't think you need more power just less wingload, I estimate yours as 36+ oz/sq ft. SAAL. |
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| ChrisS | Jul 26 2017, 08:26 AM Post #9 |
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It looks like you are doing all you can to get the best output from the motor so as Max suggests a reduction in wieght may solve the problem. Are you using any nose weight to balance? If so then making the tail lighter would allow this to be reduced. |
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| Norman Carter | Jul 27 2017, 02:38 PM Post #10 |
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As Colin Chapmen (the original Lotus designer) used to say "simplicate and add lightness". Get as much weight out of the model as you can and fly with the flaps and slats at maximum lift position rather than maximum drag, I would guess at adout 30 degrees. The Laser 100 should provide enough power, I fly my Hurri on a 90, it is lighter but has a big wing. As you say don't make the U/C too strong as you will damage the stucture rather than the tubes. If you do need more weight in the nose to get the GC correct then go for the bigger motor but it can be a route to diminishing returns, more weight, more fuel, stronger stucture, less agile, etc. I have a 2 stroke petrol motor with an inverted custom silencer that would fit, you are welcome to try this if you want, it is NGH 25 only bench run (from Just Engines), it is quite light. |
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