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General Discussion A place to talk about anything R/C or otherwise.

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  #1  
Old 2019-03-24
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A learning thread starter

What do think happened?
What would you have done to save the plane? (see the post with the youtube link)

Last edited by Sempai-mj; 2019-03-24 at 05:28 PM.
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  #2  
Old 2019-03-24
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Here's the video

Skip to the end
What do think happened?
https://www.youtube.com/watch?v=PHBw5sQzr7E
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  #3  
Old 2019-03-24
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Good approach, ...

Loss of altitude loss due to turbulence of the relief ...

Nice recovery and continuation of the approach ... this is very good except that it is not exactly on the runway ...

Instead of trying to flair hard to land, the pilot added a bit of gas to improve the touch down ...

Error. With twin gas engines, never do sudden gas at low speed ... one of the engines doesn’t respond ... twisted stoll ...

He had the chance to land hard but wanted to do better ...
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Old 2019-03-24
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His final approach was to slow and it was tip stalling.

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  #5  
Old 2019-03-25
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Quote:
Originally Posted by Dwight Macdonald View Post
His final approach was to slow and it was tip stalling.

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I agree, I would have pushed the throttle first sign of the problem and go around. Nothing wrong with going around!
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  #6  
Old 2019-03-25
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A good approach starts at the base curve. It seems he did not finish base curve at a proper speed, altitude and runway alignment (he was way left of the runway)
Combined with turbulence, he became destabilized. After that he was fighting the plane, but dangerously low.
In my view he was afraid of engine failure on go around, thats why he insisted on landing.
But seems the best course of action would have been to gradually apply power, regain control, and go around.
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  #7  
Old 2019-03-25
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I also agree with previous diagnostics:

The approach is done too slow (with high angle of attack).
They have wind bursts and/or the model seems a bit tail heavy.
A quick RPM ramp up on a twin engine will rarely be even on both sides.
All of this caused a wing tip stall 6 feet above ground (practical impossible to recover...).

This is a clear situation where a go around should have been done.
(For is defense, keep in mind that this is always easier to say when we are just watching from the the back seat ...)

Lets learn from this as an example of what not to do.

Regards,
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  #8  
Old 2019-03-25
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My two cents on the diagnostic. To add to the approach speed, evident turbulence and to all others valid explanations, there are two key points to take in consideration:

1) The drag originated by a propeller spinning at very low RPM (This is way bigger than the drag of a propeller completely stopped).

2) The "shadow" over the wings that a propeller spinning a very low RPM can cause, blocking the air flow which will translate directly to lost of lift/sustentation and faster stall.
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  #9  
Old 2019-03-25
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Good question, Michael J. and thanks for all the expert responses.
It will be a while before I’m ready for a twin, but plenty of tips even for landing an electric trainer!
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Old 2019-03-25
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Quote:
Originally Posted by Hector View Post
My two cents on the diagnostic. To add to the approach speed, evident turbulence and to all others valid explanations, there are two key points to take in consideration:

1) The drag originated by a propeller spinning at very low RPM (This is way bigger than the drag of a propeller completely stopped).

2) The "shadow" over the wings that a propeller spinning a very low RPM can cause, blocking the air flow which will translate directly to lost of lift/sustentation and faster stall.
Hi Hector, I always beleave that the idle is less drag then stopped prop...
See the following video ...my be you will change your idea...
https://www.youtube.com/watch?v=24BU15dGdJE

In the B-25 Video, You can hear the sound of the engines at the last secound : the pilot quick the gaz to inproove the touch down. One engine get bettre acceleration then the other...crash.
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