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spacestout -> RE: Hobbico Electristar Select EP Trainer RTF (10/22/2007 6:22 AM)
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Mr. Itchycods is right. I measured my Electristar engine thrust angle to the fuselage longitudinal or roll axis and found it to be 3 degrees. The firewall is actually built with the angle and the motor mounts flat. If you can examine the structure, you may be able to see where things used to be (did they slide, did the wood compress any).
Say you did increase the thrust angle on impact. In theory, assuming the structure is still rigid, you could still fly it by trimming it out or by holding control input to null out undesired direction. Its like flying a model for the first time. You set all your control surfaces to neutral and then take off and climb. Then you let the controls go to neutral and often you find that the plane wants to depart (sometimes rapidly) from straight and level. To compensate, you add trim until it flys straight and level. It is possible to have planes that are unflyable because your control surfaces can't generate enough force to correct for an out-of-balance or out of trim plane. Say you yaw drastically to the right by a radical thrust angle. You add full left rudder but still can't null it all. Not likely at 4-5 degrees, but you get my point. You still may be able to fly it but you'll have to trim to compensate.
How long your bird will fly is dependent on many things. Assuming everthing is working correctly (no shorts in motors, speed controls, batteries, etc) it comes down to how much energy you have stored in your batteries and the rate at which you draw it out. If you fly full throttle the whole flight you will drain it faster (plus risk overheating components). It is typical to use full throttle on takeoff and climb to a safe altitude, then back off to roughly 1/2, and back to full when the manuever requires it.
You need to know how long your plane will fly before taking it up. On the ground, manage the throttle as in flight and see how long to cutoff (you should cut off at 3V per cell ((talking LiPo)), or even 3.3 volts per cell. The motor will be dead, but your control surfaces will work to glide in). Then, take it in the air, staying near to the runway so you could dead stick land if needed, and fly conservatively. If you did 15 min on the ground, land after 10 minutes. There is always the chance you'll need to go around. You don't want to be on your last milliamp and not be able to make it around. All this until you are used to the plane. Time your flights.
I find a watt meter indispensible. It goes in between your battery and ESC. You can check your voltage (always fly with the batteries fully charged. The ESC makes its decisions on cutoff voltage based on initial charge). Advance the throttle. Check current flow. Are 28Amps flowing (what my plane put out new)? Are the watts (volts times amps) within the rating for motor, esc, and batteries? The meter is good in setting up your plane (especially if trying new props or batteries, etc) and in finding trouble while on the ground. Don't forget to have a full charge on the receiver battery.
I fly with two 7.4V 4200maH LiPo batteries. I would get 15 minutes. I changed props and went from drawing 28 amps full throttle to 35 amps. The plane changed from a trainer to more of a sport plane. Vertical climbs, etc. The potential was there to shorten the flight. I pay attention to how much full throttle time. The more, the sooner I land. When I charge my batteries I note how many Ah's they take. If I'm close to 4200, I know I was on the envelope. Towards the end of a flight I start to notice less available power. At that point I know it's wise to fly lower throttle manuevers and stay within a dead-stick landing of the runway.
What batteries are you flying on?
As for the motor, you can turn it by hand (with no battery). A normal motor clunks as permanent magnets approach each other. If you are hearing grinding, take it to your LHS for help.
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