Official Eflite UMX Mig 15 DF Owners Thread - Page 112 - RC Groups
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Aug 31, 2012, 01:06 PM
Registered User
Quote:
Originally Posted by pugsam
the turbulent airflow from the stalled wing can blanket the control surfaces at the tail.
That's exactly what happens if you use a thick carbon rod on the horizontal stabilizers. The turbulent airflow will badly diminish elevator authority.

If you guys use the clear plastic mod you should also consider reinforcing the elevators, if you have some tricky maneuvers in plan since it's best that the stabilizer and elevator are in the same plane (plane as in even surface, not airplane)
Beware that a nasty crash will rip the elevator control horn clean off if it's not glued to the clear plastic reinforcement as well.
Last edited by vadimpelau; Sep 17, 2012 at 12:05 PM.
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Aug 31, 2012, 01:11 PM
when down=up, up=expensive
whichwaysup's Avatar
Quote:
Originally Posted by pugsam
Very interesting, but are you saying that having a strong elevator would add to the problem?

I don't see that.

Here's a good discussion, that includes accelerated stalls and deep stalls -- which sound like possibilities for what you experienced.

http://en.wikipedia.org/wiki/Stall_(flight)

It talks about how, in a deep stall, the turbulent airflow from the stalled wing can blanket the control surfaces at the tail.

But having a weak elevator (or horizontal stabilizer) doesn't seem likely to help with that!!!???

It helps by not creating the situation in the first place. Basically, I had so much flex in the horizontal stab, combined with so much play in the control horns, that prior to bracing everything, i couldn't force the plane into the accelerated stall because I didn't have enough movement in the control surface. Make sense? Basically the "slop" in the controls was making me look like a better pilot than I am. Go figure!
Aug 31, 2012, 01:12 PM
Parkzone junkie
kalmon's Avatar
Quote:
Originally Posted by pugsam
Very interesting, but are you saying that having a strong elevator would add to the problem?

I don't see that.

Here's a good discussion, that includes accelerated stalls and deep stalls -- which sound like possibilities for what you experienced.

http://en.wikipedia.org/wiki/Stall_(flight)

It talks about how, in a deep stall, the turbulent airflow from the stalled wing can blanket the control surfaces at the tail.

But having a weak elevator (or horizontal stabilizer) doesn't seem likely to help with that!!!???

Deep stall is not an issue here. It is good old fashioned stall.

Here is a good image showing how a swept wing stalls.


What happens here is as the outboard part stalls the Center of lift shifts forward. The make the plane pitch up, which in turn makes more of the wing stall, which moved the Center of Lift forward. etc.

back on topic. Rudder, no aileron is what makes a plane stall straight or spin. If rudder authority was compromised it would definitely make a plane more likely to spin if the wing is stalled.

As the elevator, a reinforced elevator will make the plane easier to stall as there will be more authority.

-Brian
Aug 31, 2012, 01:17 PM
when down=up, up=expensive
whichwaysup's Avatar
yeah, what he said! Man, the technical definitions are so hard to understand though. let me try to say this one more time in a MUCH clearer fashion:

The gerryrigging of the flappy thingys made them strong causing the red, flying dustbuster thingy to quit flyin' straight, and then the derned pilot jest yanked on the control box control thingy's and panicked. And that made wierd stuff happen, and the flying dustbuster eventually ended up eating corn.

Clear now?
Aug 31, 2012, 01:17 PM
LiPo-Sucker & Airframe EMT
pugsam's Avatar
Quote:
Originally Posted by whichwaysup
It helps by not creating the situation in the first place. Basically, I had so much flex in the horizontal stab, combined with so much play in the control horns, that prior to bracing everything, i couldn't force the plane into the accelerated stall because I didn't have enough movement in the control surface. Make sense? Basically the "slop" in the controls was making me look like a better pilot than I am. Go figure!
Ah, that'll be next out of the Skunk Works......Slop Technology!

Aug 31, 2012, 01:21 PM
when down=up, up=expensive
whichwaysup's Avatar
New from Horizon Hobby: the Micro F4 Phantom equiped with enough slop in the control surfaces that even the biggest idiot can't hurt anyone.
Aug 31, 2012, 01:27 PM
LiPo-Sucker & Airframe EMT
pugsam's Avatar
Quote:
Originally Posted by kalmon
......As the elevator, a reinforced elevator will make the plane easier to stall as there will be more authority.
Brian, I respect the he out of your experience and expertise......but it sounds like that reasoning leads to the conclusion that elevator authority is a bad thing.....i.e., the more of it you have, the more it's possible to fly yourself into a stall.......

Isn't it more reasonable to address that in terms of "don't use too much elevator deflection"? Limit your throws, as appropriate, and don't be an over-enthusiastic yank-and-banker?

That seems better than having "sloppy" (weak or loose) control surfaces.

Aug 31, 2012, 03:57 PM
LiPo-Sucker & Airframe EMT
pugsam's Avatar
Quote:
Originally Posted by vadimpelau
That's exactly what happens if you use a thick carbon rod on the horizontal stabilizers. The turbulent airflow will badly diminish elevator authority......
Yeah, that could be a concern if the CF is too thick.

Another reason why Husafreak's skewer-insertion method is genius!

Aug 31, 2012, 04:06 PM
when down=up, up=expensive
whichwaysup's Avatar

The "I'm going flying" thread


Okay -

I thought I'd share this thread in case anyone's not already found it. It is my absolute favorite thread on this forum, so it wouldn't be fair not to let others in on the secret. Forgive me for being completely off topic.

At some point, someone started a thread about the fact that he was about to go out flying. Just a simple post expressing his excitement about the prospects of getting to go fly for a few minutes. A gazillion posts later, the thread is still going strong.

It's just a bunch of people who take a second right before they go out to fly to share their excitment, or come back from a flying session to lick their wounds, commiserate over crashes, or revel in new skills learned. Everyone is supportive, empathetic, and encouraging. It's just an awesome thread. Its a particularly good read when you're trapped at work, indoors, or just can't fly to remember why you do this.

ANyway, thought I'd share. Hope some of you subscribe.

And happy Labor Day weekend, may the wind stay low, the sun stay hot, and the wings stay on!

https://www.rcgroups.com/forums/show....php?t=1205428
Aug 31, 2012, 04:33 PM
LiPo-Sucker & Airframe EMT
pugsam's Avatar
Quote:
Originally Posted by whichwaysup
.....And happy Labor Day weekend, may the wind stay low, the sun stay hot, and the wings stay on!
Back atcha, Brother 'Sup!

Aug 31, 2012, 06:03 PM
Team30 Micro EDF
NitroCharged's Avatar
Quote:
Originally Posted by whichwaysup
yeah, what he said! Man, the technical definitions are so hard to understand though. let me try to say this one more time in a MUCH clearer fashion:

The gerryrigging of the flappy thingys made them strong causing the red, flying dustbuster thingy to quit flyin' straight, and then the derned pilot jest yanked on the control box control thingy's and panicked. And that made wierd stuff happen, and the flying dustbuster eventually ended up eating corn.

Clear now?
That's gold, Jerry! Gold!

That's gold, Jerry! Gold! (0 min 17 sec)
Aug 31, 2012, 07:19 PM
Registered User
daniel_arg's Avatar

+4 grams, new look


A bit of work, and a new "Alfamodel" like look
Aug 31, 2012, 08:39 PM
Do you see what I see?
rcoconut's Avatar
That lightning bolt looks really cool back there on the vert fin! As well as the red 'round the air intake!!

NICE job!
Sep 01, 2012, 02:03 AM
Registered User
daniel_arg's Avatar
Quote:
Originally Posted by rcoconut
That lightning bolt looks really cool back there on the vert fin! As well as the red 'round the air intake!!

NICE job!
Thanks!
Sep 01, 2012, 11:27 AM
WHAT THE...
barmonkey's Avatar
Just picked one of these up a couple of days ago. I was hoping for a maiden, but it looks like a few days of rain ahead. Unfortunately, the rain isn't my only isssue. I was checking the control surfaces and one of the aileron servos quit responding...right now I am wondering if I should send it back or just buy a new servo. Any thoughts?


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