Tip Stals and CG
08-24-2006 | 12:54 PM
#26
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From: Fresno, CA
RE: Tip Stals and CG
ORIGINAL: mesae
I have been ramp checked (uneventful) but that's not why I wrote what I wrote. I'm an ƒáá employee and I design instrument flight procedures. We're not all bad I hope, but having flown for a living I understand the perception.
ORIGINAL: RaceCity
...
My favorite FAA line???
"I'm from the FAA and I'm here to help!"
(Great!...why don't you start by filling out this trip release!!!)
...
My favorite FAA line???
"I'm from the FAA and I'm here to help!"
(Great!...why don't you start by filling out this trip release!!!)
I have been ramp checked (uneventful) but that's not why I wrote what I wrote. I'm an ƒáá employee and I design instrument flight procedures. We're not all bad I hope, but having flown for a living I understand the perception.
Have worked with some great Feds.. the ones with real world experience have been terrific. They know what the FAA needs, and what the customer needs and work to solve issues collaboratively.
IMO the Feds who were hired because they could identify an airplane three out of five times, then issued Inspector's credentials are the pinheads who make life miserable and tarnish the name of the FAA and the efforts of the "good guys" who toil there...
08-24-2006 | 01:56 PM
#27
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From: Edmond,
OK
RE: Tip Stals and CG
ORIGINAL: Jimmbbo
...
Have had seven friends go to work for the FAA - one quit in a year, another a year later, one died of a heart attack, another of a stress related stroke - probably not a good recruitment statistic.
Have worked with some great Feds.. the ones with real world experience have been terrific. They know what the FAA needs, and what the customer needs and work to solve issues collaboratively.
IMO the Feds who were hired because they could identify an airplane three out of five times, then issued Inspector's credentials are the pinheads who make life miserable and tarnish the name of the FAA and the efforts of the "good guys" who toil there...
...
Have had seven friends go to work for the FAA - one quit in a year, another a year later, one died of a heart attack, another of a stress related stroke - probably not a good recruitment statistic.
Have worked with some great Feds.. the ones with real world experience have been terrific. They know what the FAA needs, and what the customer needs and work to solve issues collaboratively.
IMO the Feds who were hired because they could identify an airplane three out of five times, then issued Inspector's credentials are the pinheads who make life miserable and tarnish the name of the FAA and the efforts of the "good guys" who toil there...
My job is nothing like that. I have flexible hours, good benefits, good pay, a good boss, etc. But the adm. is another story. Anti-labor, pro-airline, pro-contracting, and by extension, anti-GA. Of course this is just a subjective impression, subject to bias and error on my part and by no means official. Some of the recent changes should result in overall better service to the public.
Now that I'm in, i'm gunning for a flight inspection flying job. I expect to hear something any day now on my recent inverview.
08-24-2006 | 10:05 PM
#28
Thread Starter
Senior Member
RE: Tip Stals and CG
Thanks for the CG calculation link, I've been looking for it, lost the bookmark long ago.
I don't know about too heavy, but it's a very distinct possibility. I've been cleaning on this plane tonight and it is a little heavier than any of my other 40 sized planes. Ok, I'll give in on which plane. It's a Mile High Wings XACT MKII sporting a Magnum 52 two stroke.
It's not my favorite in the hanger but I'm sure it'll get better.
I don't know about too heavy, but it's a very distinct possibility. I've been cleaning on this plane tonight and it is a little heavier than any of my other 40 sized planes. Ok, I'll give in on which plane. It's a Mile High Wings XACT MKII sporting a Magnum 52 two stroke.
It's not my favorite in the hanger but I'm sure it'll get better.
08-27-2006 | 02:55 PM
#29
Thread Starter
Senior Member
RE: Tip Stals and CG
Ok, I finished the CG test off the website given above. The CG should be almost a full inch aft of specs according to the calculations. I checked it and added 1/4 ounce to the nose over what was already added. Unfortunatly, while charging the battery at the field it caught fire. The battery must have had a shorted cell(Ni-Cad). No damage to the plane and a new battery is ordered. Will test fly next week.
08-29-2006 | 08:52 AM
#30
Senior Member
RE: Tip Stals and CG
ORIGINAL: mesae
How did you attempt to recover from these tip stalls? It is very unusual for a simple tip stall to be so prolonged unless it develops into a spin. It is either an extremely poorly designed/setup airplane, or you you were not relaxing the elevator when the stall occurred. Not relaxing the elevator, or worse yet--increasing the elevator would prevent recovery by causing secondary, tertiary, quaternary, etc. stalls.
I always set up my airplanes so they tip stall easily since I really enjoy good snap roll characteristics. Of course setups like this demand respect and will punish me severely for mishandling the elevator and/or rudder.
If it always snaps to the left, regardless of power setting, then most likely your left wing has wash-in (warped), or your rudder is significantly out of trim to the left. If it only does this when substantial thrust is being produced, then it is likely caused by propeller-induced left yaw, and you are not correcting for it with rudder, or your rudder is again perhaps out of trim. The aft CG causes the airplane to be more sensitive to any imperfection in trim. Moving the CG forward may have masked this, which is fine if it flies the way you like. Anyhow it sounds like you are happy with it now, which is what's important. I hope this helps.
ORIGINAL: Tim Taylor
The plane I was writing about is a 46 size composit pattern plane. The plane never flew like it was tail heavy at all, I just had major unexpected tip stalling to the left at any speed. I wrote the makers and they said, "It's suppose to do that." Well, I could see a little tip stalling but not unrecoverable tip stalls, like getting control back 5 feet off the ground? I've have other planes that may tip stall but they're nothing like this one was. The problem came as I was removing weight from the nose after the maiden. I originally had about 1/2 ounce lead in the nose and I removed it. It was a couple weeks before flying the plane again and I had not placed the correlation between the tip stalls and the removal of lead. Now it seems to fly well with almost no tendencies to tip stall. It's about 1/2 ounce nose heavy now by the makers specs.
Thanks All.
The plane I was writing about is a 46 size composit pattern plane. The plane never flew like it was tail heavy at all, I just had major unexpected tip stalling to the left at any speed. I wrote the makers and they said, "It's suppose to do that." Well, I could see a little tip stalling but not unrecoverable tip stalls, like getting control back 5 feet off the ground? I've have other planes that may tip stall but they're nothing like this one was. The problem came as I was removing weight from the nose after the maiden. I originally had about 1/2 ounce lead in the nose and I removed it. It was a couple weeks before flying the plane again and I had not placed the correlation between the tip stalls and the removal of lead. Now it seems to fly well with almost no tendencies to tip stall. It's about 1/2 ounce nose heavy now by the makers specs.
Thanks All.
How did you attempt to recover from these tip stalls? It is very unusual for a simple tip stall to be so prolonged unless it develops into a spin. It is either an extremely poorly designed/setup airplane, or you you were not relaxing the elevator when the stall occurred. Not relaxing the elevator, or worse yet--increasing the elevator would prevent recovery by causing secondary, tertiary, quaternary, etc. stalls.
I always set up my airplanes so they tip stall easily since I really enjoy good snap roll characteristics. Of course setups like this demand respect and will punish me severely for mishandling the elevator and/or rudder.
If it always snaps to the left, regardless of power setting, then most likely your left wing has wash-in (warped), or your rudder is significantly out of trim to the left. If it only does this when substantial thrust is being produced, then it is likely caused by propeller-induced left yaw, and you are not correcting for it with rudder, or your rudder is again perhaps out of trim. The aft CG causes the airplane to be more sensitive to any imperfection in trim. Moving the CG forward may have masked this, which is fine if it flies the way you like. Anyhow it sounds like you are happy with it now, which is what's important. I hope this helps.
09-02-2006 | 05:16 PM
#31
Thread Starter
Senior Member
RE: Tip Stals and CG
I managed to get some time on this plane today. It flew great. No problems at all. It does everything it's supposed to. The CG was the problem.
09-05-2006 | 09:37 AM
#32
Senior Member
RE: Tip Stals and CG
Hi!
Stall is an aerodynamic phenomena and has NO relation with CG position... BUT:
1- A aft CG (tail heavy) helps to reach high AOA, so stall can ocurr due to High AOA
2- An Fwd CG (nose heavy) can even be helpfull for avoiding stalls because plane can reach what we call "Trim"... the pitch moment due to the heavy nose is too big, so the tail pitch moment (considering maximun deflection) is not enough and AOA "stops" growing up before stall appears. This is a rare situation but could happen in some planes...
Conclusion: CG position can determine whether the stall AOA is reached or not (in most planes this point is reached); stall is an aerodynamic phenomena.
About tip stall: appears only in tapered wings because the tip chord is smaller so stalls before the root choords. The "perfect wing" which stalls completely at the same time is elliptical (like supermarine spitfire) while non-tapered wings tipically stalls from the center to the tips (named "safe stall"; all trainer stalls like this...)
Hope my comments are usefull to all...
Stall is an aerodynamic phenomena and has NO relation with CG position... BUT:
1- A aft CG (tail heavy) helps to reach high AOA, so stall can ocurr due to High AOA
2- An Fwd CG (nose heavy) can even be helpfull for avoiding stalls because plane can reach what we call "Trim"... the pitch moment due to the heavy nose is too big, so the tail pitch moment (considering maximun deflection) is not enough and AOA "stops" growing up before stall appears. This is a rare situation but could happen in some planes...
Conclusion: CG position can determine whether the stall AOA is reached or not (in most planes this point is reached); stall is an aerodynamic phenomena.
About tip stall: appears only in tapered wings because the tip chord is smaller so stalls before the root choords. The "perfect wing" which stalls completely at the same time is elliptical (like supermarine spitfire) while non-tapered wings tipically stalls from the center to the tips (named "safe stall"; all trainer stalls like this...)
Hope my comments are usefull to all...
09-05-2006 | 09:40 AM
#33
Senior Member
RE: Tip Stals and CG
ORIGINAL: Tim Taylor
I managed to get some time on this plane today. It flew great. No problems at all. It does everything it's supposed to. The CG was the problem.
I managed to get some time on this plane today. It flew great. No problems at all. It does everything it's supposed to. The CG was the problem.
... because stability margin of your plane was near "0"... i.e.: CG was so near of center of pressure that the minimum input to any command resulted in a reallly big pitch moment.
09-05-2006 | 07:39 PM
#34
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From: Edmond,
OK
RE: Tip Stals and CG
ORIGINAL: guille2006
...About tip stall: appears only in tapered wings because the tip chord is smaller so stalls before the root choords....
...About tip stall: appears only in tapered wings because the tip chord is smaller so stalls before the root choords....
Not true. A tip stall, meaning one wing stalls significantly before the other, resulting in roll, can occur with any wing planform. A "tip stall" is required to do a spin or a snap roll and there are many constant-chord winged airplanes that can do decent spins and snaps.
09-05-2006 | 09:26 PM
#35
Senior Member
RE: Tip Stals and CG
One of my SAE Lifters with a constant chord wing, lots of tip dihedral, no ailerons, has a tip-stall, but it recovers much better than an aileroned wing does.
I was (pleasantly) surprised to see this.
I was (pleasantly) surprised to see this.
09-05-2006 | 10:05 PM
#36
Senior Member
RE: Tip Stals and CG
And I've got a pet peeve.
The term "tip stall" is way over used. Anytime one wing stalls or drops before the other it's called a tip stall by most RC flyers. Guess there actually isn't a better term to use. But it's not necessarily right.
The term "tip stall" is way over used. Anytime one wing stalls or drops before the other it's called a tip stall by most RC flyers. Guess there actually isn't a better term to use. But it's not necessarily right.
09-05-2006 | 10:14 PM
#37
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From: Edmond,
OK
RE: Tip Stals and CG
ORIGINAL: darock
And I've got a pet peeve.
The term "tip stall" is way over used. Anytime one wing stalls or drops before the other it's called a tip stall by most RC flyers. Guess there actually isn't a better term to use. But it's not necessarily right.
And I've got a pet peeve.
The term "tip stall" is way over used. Anytime one wing stalls or drops before the other it's called a tip stall by most RC flyers. Guess there actually isn't a better term to use. But it's not necessarily right.
How about tippy stall?
09-17-2006 | 12:20 PM
#39
Thread Starter
Senior Member
RE: Tip Stals and CG
ORIGINAL: darock
And I've got a pet peeve.
The term "tip stall" is way over used. Anytime one wing stalls or drops before the other it's called a tip stall by most RC flyers. Guess there actually isn't a better term to use. But it's not necessarily right.
And I've got a pet peeve.
The term "tip stall" is way over used. Anytime one wing stalls or drops before the other it's called a tip stall by most RC flyers. Guess there actually isn't a better term to use. But it's not necessarily right.
'Narrowly escaping a crash due to the wing going where it wants to go rather than where you want it to go - stall'
Here's a picture of my latest future supply of kindling.
