RCU Forums - View Single Post - Four Star 60 Firewall
View Single Post
Old 05-18-2008 | 06:51 AM
  #42  
zeuglodon's Avatar
zeuglodon
My Feedback: (1)
 
Joined: Jun 2004
Posts: 110
Likes: 0
Received 0 Likes on 0 Posts
From: Howland, OH
Default RE: Four Star 60 Firewall


ORIGINAL: Montague


ORIGINAL: smithbrl
Montague
Thanks for your input. What should I do the next time this happens?
Thanks Cecil
When a plane drops nose-down out of a turn, then you've probably stalled the wing by getting the AOA too high. The way out is center the controls, let the plane build up a little airspeed, then pull out gently. The problem here, obviously, is that this kind of crash happens most often when turning to final, low and slow, and there isn't always enough altitude to make the save. Sometimes, once the plane gets too slow, you've crashed and just don't know it yet.

The good news is that for most models, you actually don't have to build that much airspeed back up, most sport planes will get enough airspeed almost instantly, and you can just release the controls, then almost immediatly start pulling out.

The key is the pull as gently as you can, since if you pull too hard here you'll just stall again and be back where you started, just lower.

Obviously, higher wingloadings and rearwards CGs make this kind of thing worse. I see that the plane is question is a .40-size plane with a .75 in it. How's the all up weight compare to the kit recommended rage? half a pound on the heavy side, but still flys great? Wouldn't surprise me. I have a .40 size Sukhoi with a S.T. .75 in it that's a alot of fun, but is really nasty if it gets slow.

Btw, while you might not think the plane was in a "spin", and it probably wasn't in a fully developed spin like you get when you do one as an acrobatic maneuver, the effect is the same, you stalled the wing. In a "spin looking spin", you stall one wing much more than the other, and get that fast rotation, while the less stalled wing still produces some lift to hold the nose up. When falling out of a turn, you usually end up with both wings stalled almost the same, just a little differnece to get some rotation going, but not enough to pop the nose up. The result looks like a diving spiral, but you're still stalled. In these cases, the ailerons sometimes work backwards, since when you try to roll left, you increase the AOA on the right wing, and decrese the AOA on the left. But if the right wing is stalled, increasing the AOA over there just makes the stall worse, and instead of increasing lift over there, lift decreases. In this way, holding left aileron to get out a sping going to the right can actually make the situation worse. It does depend on the plane though.

As someone who pulled this dumb-thumb maneuver several times and blamed everything but myself before figuring it out, I can vouch for the absolute accuracy of this post. I only wish I had someone to analyze my first "low, slow, too-much bank" crash. It would have saved me a couple of rebuilding jobs.

Rick