Jetdesign

My Feedback: (8)

I guess I'm curious what a stall looks like, I might have done one, twice, without knowing it.

Coming in for a landing, once on Wednesday and one today, I was turning in to final, when my plane got "hit". I thought I lost total control, and the plane turned completely around and ended up flying away from me, doing some pretty wild moves. My stick corrections seemed to have little to no effect. Since I was coming in for landing, I was low on power. I throttled up so my corrections would have more effect, and was able to safely bring the plane in to land. Almost lost it today.

Driving home, I realized that maybe I stalled? I couldn't get control until I gave it more throttle, so maybe it was in a stall condition the whole time, and I really wasn't getting hit.

Only thing, though, is that all day I was just flying above idle, getting used to low flight characteristics, and shooting touch-and-gos, getting used to my plane. I think I would have known if I was too low on throttle, and I know I was a few clicks higher than when I was coming in as slow as possible. But then there's always the possibility of a gust of wind changing everything. Was at the point of the plane being pretty mushy responding to controls, maybe pretty close to stall speed, but again, I feel like I would have known that. Maybe not.

Does this sound like a stall? My trainer said I was in a spot known to interfere with 72mhz radios though. I range check fine, but then brought the plane physically to the spot where it happened, and left the radio with a guy at the flight line. Just as I got past the end of the runway, the servos started to make some noise. No control surface movement, but definitely a groaning noise coming from the electronics. Plane flies absolutely fine anywhere else, and at plenty of distance, but this happened just long of one end of the runway, again during approach.

So I was wondering if people could talk about what happens when a newbie first encounters a stall; what happens to the plane, how do they react, and is it similar to this?

Thanks guys!

ply2win

My Feedback: (3)

The way a plane behaves in a stall is different depending on what type of plane it is. However, your statement that you were able to control it again after you gave it throttle makes me believe it was a stall. It also could be that you were overcontrolling the plane when it was too slow.

If you had lost control of the plane due to interference the throttle wouldn't work properly either. I hear a lot of people talking about getting "hit" but I have yet to experience that in 3 years of flying at several different fields.

If the wind allows, you could always try and land from the other direction and see what happens.

Campgems

Each plane has it's own stall behaivor. Some drop their nose and start down. Some will tip stall, one wing quits flying and it rolls into a knife edge and goes in. Some planes give you warning, musshy controls and loss of stability. Others just drop.

What you describe sounds like it was about to stall but hadn't got quite to it yet. You are very lucky to have recovered it.

I lost my 4*60 a couple months back, doing just as you describe. I had a strong head wind straight down the runway. I was throttled back more than I should have been, I was gaging the ground speed, not air speed. When I started my final turn to quick and then turned back to correct my approach, I had no air speed. My 4* just dropped it nose and went down like a lawn dart with no warning. I've watched a couple guys drop their Yak 54 and Extras by using flaperons and not taking into account that a quick aileron change could stall out the wing. Wing over at 20 ft and then pick up parts.

It would be a good idea to practice stalls. Way up high go you can recover. Just setup on a straight line and keep cutting power and applying more up elevator until it starts it drop. Pour on the coal and accelerate out of trouble. See how the plane handles. Try it both up wind and down wind. The key thing is to gain airspeed as soon as you can.

Don

ChuckW

Your Dolphin should have good stall characteristics. I would think it should anyhow based on the overall design. Most planes like that I have flown with constant chord wings, big wing area and the light wing loading that results tend to stall pretty gently. The GP Cherokee for instance just sort of tips forward a little, picks up speed in the descent and starts flying again. Nothing scary about it at all unless you are right on the deck. You REALLY have to try and make that happen too; it is hard to stall. Same goes for a 4-star. I've never intentionally stalled one but they seem to float along forever going slower and slower without stalling.

Other airplanes are a different story. Get them too slow and they'll drop a wing & snap into the ground or just suddenly fall out of the sky. That's why a lot of really aerobatic planes aren;t good for beginners. That ability to stall easily helps in many maneuvers but can be dangerous for an inexperienced pilot.

Never having flown a Dolphin, I really can't say how it stalls.

To me it sounds like either a serious radio hit r a case of over-controlling. Could be dumb-thumbs too; we all suffer from that on occasion.

Another thing to remember is keep the nose down slightly on your approach. This helps keep airspeed up and the wing flying. Rotate to level when you are just a few feet off the ground.

opjose

A "hit" tends to cause ALL control surfaces to deflect randomly or in different directions.

Usually the plane will be flying along at normal speeds when it will suddenly and inexplicably change orientation, throttle, pitch, etc.

Even when it's heading toward the ground at high speed, the surfaces will appear to have no effect as they may not be active.


Gusts can sometimes be misinterpreted as "hits", particularly when a sudden gust flips the plane over. A seasoned pilot is able to quickly recover control, but a rookie may find things happening way too fast.

Usually a gust of wind will change the orientation only in one or two directions w/o a sudden decrease or increase in throttle.

Jetdesign

My Feedback: (8)

Hmm. I definitely was flying the plane all afternoon really close to, if not at, stall speed. I was flying where I had to keep the nose pointed maybe 20 to 30 degrees up, using lots of elevator, and the plane was still sinking. Tip stalls would happen, and power and/or opposite aileron would correct it.

What gets me about what happened is that the plane completely got turned around and was flying away from me, and was rolling and almost looping on its own. I guess it's hard to say what happened. I think/imagine the stall characteristics of the plane are pretty gentle, at least from what I have seen so far. I can't imagine the plane turning itself around from a stall, in the opposite direction that I was turning in to final from.

Dunno. I guess some more investigation to noise in that area is a must.

I did bring it around to the other side of the field to land it. Unfortunately I don't know if/when the throttle kicked in, if it did it immediately or not. I was struggling with the plane for quite a while, and actually think the throttle might have kicked in later, when I regained control, but can't really remember.

ChuckW

What you are describing is called a harrier in the 3-D world. A plane like the dolphin really isn't meant to be flown like that. With that slow speed and high angle of attack, you almost certainly stalled the airplane. When you cut the throttle, keep the nose slightly down to maintain enough airspeed to keep the wing flying. Then slowly add up elevator to level out and stay that way a feet above the runway when landing.

In my opinion, I would stop this type of high alpha flight with that particular airplane. It isn't designed to do it and you won't ever learn to fly well doing it either. Remember... straight and level, precision, control, good landings, etc. make a good pilot. Master those first. Save the crazy stuff for a few planes and some time from now.

Campgems

Are you flying a PPM or PCM receiver? You may have gone into a brown out and the receiver shut down for a couple seconds. Lot of flying that day could have left you with a battery that wasn't 100% and you happened to induce a little extra load and tripped it off.

Just a thought. It would explain your trun also as the controls would lock where you had them last. A little aileron and around you go.

Don

OzMo

My Feedback: (3)

Watch the other pilots land and look for a wag of the tips. This is a clue airspeed is marginal. The seasoned guys will allow the nose to drop to keep airspeed and control or blip a little throttle. remember the ELEVATOR controls airspeed on approach!
Try a blip of gas as the plane is settling into the flair, the air presure increase when the plane is so close to the ground really softens the landing.

Also try some 20' high stalls close in so you can see how the plane reacts. Do several and play with the elevator fine inputs.
After a few of these the little light in the back of your brain will come on!

Hypersprint

Sounds like you might be getting close to doing a Harrier



I guess I need to learn to type faster

Jetdesign

My Feedback: (8)

Well the 'high alpha' flight was me just trying to figure out what happens to my plane in different situations; I don't normally fly that way, nor was I flying that way when I had whatever happened happen to me. I was turning into final with the nose maybe 5 degrees down when it happened. I just brought that up because I was trying to learn stall characteristics, so I was trying to get into a stall situation, and was trying to explain that I didn't think I was that close to a stall. When I did that, the wings wanted tip, and the plane wanted to sink. I kept it up as long as I could with low power, then pulled out with some throttle.

I have PPM (FM) receiver. 2300mah battery, and Voltwatch showing second to highest green bulb. Is PPM better for this kind of stuff? Is it worth spending $100 on a new receiver?

bkdavy

My Feedback: (1)

I would say you were definitely stalled.

Another aspect of stall recovery that many beginners are not used to: Once the wing stalls and the plane starts to spin, ANY control inputs other than throttle are going to deepen the stall. That is why stalls are frequently mistaken for radio hits. With a stalled wing, adding aileron will not have the normal effect, and that feels like a radio hit. Same with elevator and rudder. In fact, the control inputs make the gyrations of the plane seem worse. Thats how you ended up turned around.

When you're landing, try to keep the nose level, or maybe one or two degrees up. This will help keep you away from the stall condition.

Brad

Campgems

You should have been good to go. The slow startup is with a PCM. So we can scratch that off the list of posibilities. I think the stall vote are wining this poll.

Don

ChuckW

One other thing to consider... is this the same receiver that has been through 2-3 crashes? If so, did you get it checked out and repaired if needed? I witnessed what happens when you fail to do this a few weeks ago. A guy at my club had a beautiful GP Shoestring and used a receiver from a crashed airplane. In spite of experiencing a couple glitches in a previous flight, he convinced himself everything would be OK. On final approach, the plane glitched bad an basically spun into the ground.

Disgusted, he vowed that he had learned his lesson and tossed the receiver in the trash. Miraculously, he was able to rebuild the plane but it will never be quite the same.

After my Cherokee went in, my Spektrum receiver was in the mail on it's way to Horizon first thing on the Monday after. I'd rather play it safe. If the repair cost is too high, I will scrap it and get a brand new receiver.

panzerd18

If you do not know what a stall is why don't you Google it, there is heaps of information. Like this http://en.wikipedia.org/wiki/Stall_(flight)

kid chuckles

A stall is when your plane falls out of the sky from just plain going to slow. If it weighs 5lbs. thats alot to keep from just falling because of gravity. When you get to slow gravity takes over and down it goes. Not enough wind over or under the wings to keep 5lbs. floating. EASY. lol. Drop a 5lb plane and see what you would think it takes to keep it from falling. Like the Duke boys jumping a pond. going fast they made it. Going slow half way and fall into pond. Slow down to muvh you will Stall.

Campgens I did the very same thing the other day with a Frenzy. Just was flying slow into the wind and turned and never throttled up. Brain dead and knew better.

Jetdesign

My Feedback: (8)

I'm starting to think it was a stall, too. I had low power and was using a decent amount of elevator into base. I can't remember all that clearly, but I think I might have been turning too hard with the ailerons, and using more and more elevator to complete the turn. The bit above about the control surfaces actually worsening the stall makes a lot of sense, and this could have been exactly what happened. It seemed like what I would expect a hit to feel like; I lost total control of the plane, and it seemed to be flying on its own. What I am guessing happened is that it was in a bad stall, but the forgiving nature of the plane allowed it to mush into a position to gain some airspeed, which made it seem like it was still flying. Since the plane was getting far away, and flying away from me, there was a bit of a lag before the throttle input was received, the engine sped up, and the prop got enough RPM's to actually start flying.

I'm actually hoping it was a stall (both times!) so that I can feel safe flying over that spot again. The president, treasurer, and safety officer of my club all checked out my plane and receiver, and all gave me the go ahead to fly it after my crashes. We have A LOT of unoccupied real estate (big farm) and I was flying it up to great distances with no problems. The only times I had a problem were turning in to final at low power.

I thought I knew what a stall was; didn't realize they could get so drastic!

ChuckW

Doing a range check cannot always determine a receiver is OK after a crash. Vibration, temperature and other factors can reveal damage to the internal components. This could easily be missed during a simple range check. It may even be fine "most of the time when flying". When all of the conditions are right though... bad stuff happens.

The ONLY way to determine if a receiver is OK after a crash is for a qualified technician with the proper equipment to disassemble, inspect and test it. Unless your club president, treasurer and safety officer are trained and have access to this stuff, they should have recommended that you send your receiver in. I'm sure they are good guys and great pilots but I'm sorry... I think they gave you bad advice. I'm not trying to be harsh or mean but that is my honest assessment.

I would be VERY suspect of your receiver. It has been through 3 crashes, two of them pretty violent based on your descriptions.

RC flying is inherently risky. There is a chance we'll mess up as pilots, a chance good parts or structures will fail, a chance for radio interference and whole bunch of other stuff. We must make sure to minimize the chance of things going wrong.

I'm not saying that I know for sure your radio receiver is a problem. I will say that you need to be suspicious of it though and don't trust it until you know for certain that it is certified as OK.

Jetdesign

My Feedback: (8)

Chuck, I believe what you are saying. I was talking about sending in my receiver, and literally EVERYONE at my club told me I was nuts to do so. I heard everything from "just do a really thorough range check" to "90% of the time it's just the crystal" (I got a new crystal) to "receivers are pretty tough." So it was easy for me to take the easy road and just range check the receiver several times. I'll have it checked out though, there's a link around here somewhere for $15.00, so I'll find it and have it checked.

But like you said, when the conditions are right...

I'm really having a tough time getting the plane to come in slow. Two clicks above idle and the plane is a pile of mush, needing lots of rudder and plummeting down out of the sky. 3 clicks above idle and my instructors are telling me that I need to work on coming in slower (don't understand what's wrong with faster landings though). So I was trying to practice coming in as slow as physically possible.

combatpigg

My Feedback: (3)

Isn't the Dolphin the one that everyone is raving about being a great 2nd plane?

Allfat

My Feedback: (1)

Yeah, it is a copy of the Sig 4*

Jetdesign

My Feedback: (8)

Yep. I still love the plane, don't think this means it's not a great second plane. Although it's all I know. It just seems to like to go fast.

combatpigg

My Feedback: (3)

A good flying .40 powered plane in this size range should weigh no more than 4 pounds for great all around handling. The RC pilot shouldn't feel like he is balancing a balloon on a stick when he slows his plane down. I agree with the advice to have a crashed RX checked out. The most expensive way to do this hobby is to try to do it cheaply, paying upfront for a RX checkout is cheap insurance.

Jetdesign

My Feedback: (8)

Hmm, maybe it's too heavy? I added after market landing gear, but definitely not a pound of additional weight. And axles and a small strip of ply, and lots of epoxy. For repairs I added 4 small sticks of balsa, 2 medium sticks, and glue. Removed the pilot in the canopy, which probably weighed as much as all the balsa I added.

Should I weigh my plane? Loaded with gear and engine?

Nathan King

HA! No way it's too heavy. I currently have a scale model in my hangar whose wing loading comes out to 43 oz/ft^2 and it flies fine (if you fly on the wing and don't have an engine quit ).

Do you need to send in the receiver? Well, that depends on how much risk you are willing to accept. I always like to mitigate my risk as much as possible, so I would send it in. Since I fly some pretty expensive stuff I always send in my transmitter during the winter for a checkup as well. That's probably overkill for anyone besides an anal retentive nut though.