Climbing issues

Bitconnect
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Climbing issues

Post by Bitconnect » January 5th, 2020, 10:30 am

My plane flies relatively straight on low turn (~800 turn) flights but when I wind to ~2000 turns, the plane climbs to maybe 10 feet and then hovers and stalls, diving towards the ground right after. I have tried decreasing the wing incidence and moving the cg back to no avail. I can't figure out what needs to be changed in order for the plane to start climbing.

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Re: Climbing issues

Post by Lorant » January 5th, 2020, 12:06 pm

stick with high number of rotations, use a torque meter to measure climb and observe stall at a specific initial torque. Then, wind your rubber until it is near breaking and dewind to a torque value you know your plane can safely climb yet not stall at. Other things you could try are potentially lighter rubber or re-trimming the plane.
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Re: Climbing issues

Post by coachchuckaahs » January 5th, 2020, 12:31 pm

Trim your plane (incidence, CG) for good flight in cruise and letdown. Don't change trim for climb, there are other adjustments to make,

If it is stalling in climb, you may have too little static stability. This means you need to move your CG FORWARD, not back. Add weight to the nose, re-trim incidence for good cruise/letdown (low torque stage), and then try higher torque launch.

It is possible that you have differing incidence top and bottom wing, which may cause the higher incidence wing to drive a stall at higher speed. Carefully check that the top and bottom wing have the same incidence.

It is possible you have too much wash-in on your left wing. Even if you don't have a lot, the motor stick may be twisting and adding more for the high torque state. Try less wash in.

These planes are VERY sensitive to CG, so if everything else is straight, that is where I would start. And Lorant makes a good point. Launch with a known torque, not a known winds. Wind to almost breaking, then back off to desired launch torque.

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Re: Climbing issues

Post by madhavaniyengar » January 5th, 2020, 7:44 pm

Bitconnect wrote:
January 5th, 2020, 10:30 am
My plane flies relatively straight on low turn (~800 turn) flights but when I wind to ~2000 turns, the plane climbs to maybe 10 feet and then hovers and stalls, diving towards the ground right after. I have tried decreasing the wing incidence and moving the cg back to no avail. I can't figure out what needs to be changed in order for the plane to start climbing.
If this is happening at the very beginning of the flight, I find that decreasing the launch torque helps a lot to avoid it. You can do this by de-winding the rubber after you put in all your winds or by just holding it in your hand for a second before launching.

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Re: Climbing issues

Post by jander14indoor » January 6th, 2020, 7:51 am

Sounds like a power stall. Instead of giving up fuel by backing off turns, consider adding down thrust (1 or 2 degrees) to the propeller.

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madhavaniyengar
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Re: Climbing issues

Post by madhavaniyengar » January 6th, 2020, 4:21 pm

jander14indoor wrote:
January 6th, 2020, 7:51 am
Sounds like a power stall. Instead of giving up fuel by backing off turns, consider adding down thrust (1 or 2 degrees) to the propeller.

Jeff Anderson
Livonia, MI
That sounds interesting, how would you go about adding down thrust to the prop?

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Re: Climbing issues

Post by CrayolaCrayon » January 7th, 2020, 5:38 am

madhavaniyengar wrote:
January 6th, 2020, 4:21 pm
jander14indoor wrote:
January 6th, 2020, 7:51 am
Sounds like a power stall. Instead of giving up fuel by backing off turns, consider adding down thrust (1 or 2 degrees) to the propeller.

Jeff Anderson
Livonia, MI
That sounds interesting, how would you go about adding down thrust to the prop?
If you have a harlan bearing, you can lightly bend the front down with pliers, or even your finger if you keep the right points of contact.
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Re: Climbing issues

Post by jander14indoor » January 7th, 2020, 5:06 pm

Depends on the design of your prop hanger. The general idea is to change the axis of the prop shaft so it points down a couple of degrees.
Some prop hangers can be bent down, some you have to re glue with a down angle.
Most indoor designs recommend this.

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Bitconnect
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Re: Climbing issues

Post by Bitconnect » January 17th, 2020, 2:13 pm

added ~1-2 degrees downthrust and took some weight off the tail and added it all to the front. Flies ~80 seconds turning left but stalls when climbing while turning right. Eventually corrects itself but the stall sacrifices a lot of height and results in a very large flight path. Not sure why the right turn is like this.

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Re: Climbing issues

Post by coachchuckaahs » January 17th, 2020, 5:05 pm

Bitconnect wrote:
January 17th, 2020, 2:13 pm
added ~1-2 degrees downthrust and took some weight off the tail and added it all to the front. Flies ~80 seconds turning left but stalls when climbing while turning right. Eventually corrects itself but the stall sacrifices a lot of height and results in a very large flight path. Not sure why the right turn is like this.
Right and left circles are different because the prop is turning the same way, causing the plane to want to roll to the left (inward fro left circle, outward for right circle). This impacts a number of trim areas.

You may try adding more rudder for the right turn (in small increments), or reducing right wing wash in.

Coach Chuck
Coach, Albuquerque Area Home Schoolers Flying Events
Nationals Results:
2016 C WS 8th place
2018 B WS 2nd place
2018 C Heli Champion
2019 B ELG 3rd place
2019 C WS Champion
AMA Results: 3 AAHS members qualify for US Jr Team in F1D, 4 new youth senior records

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