Eddym

I have recently completed a Great Planes Shoestring ARF. It has an OS 70 surpass FS and futaba radio. I have flown it 3 times. It is balanced and flies well. However it lands fast! I have programmed the radio with flapperons but when I deploy them (high altitude test) the aircraft wants to role. Has anyone with this aircraft dealt with this? Do you have to mix ‘Up� elevator trim? Landings are manageable without this function but it would be nice to slow it down some.

maukaonyx

I've got one with the same engine as you in fact. It does like to land hot doesn't it! I use flaperons and yes some elevator mixed in. Mine pitches down with just the flaperons down. I don't have much dialed in , perhaps the ailerons go down about 1/4" or just a wee bit more. I have enough up elevator mixed in to level the plane while at a low throttle setting. It slows the plane enough to make controlled landings that don't raise my blood pressure. Before I established this setup, I was landing without flaperons and was having a hard time, enough to delam one side of the LG a little. Since then, no further delaminations. BTW I fly off grass. OH, just be sure your ailerons go down the same amount when deployed...maybe yours are just a bit off from each other? My plane does not yaw or roll due to flaperon use. Jon

speedracerntrixie

My Feedback: (29)

A fast landing airplane is usually a sign of being nose heavy

red head

I was just going to comment that we had a plane at the field ( like a shoestring ) that was having landing problems. We set the CG back a little and it made all the difference in the world.

Another note along this line: I had a plane that landed to fast and ended up putting a 3 bladed prop on it and loved it. I don't know how that would effect a 70, mine was a 90. ENJOY !!! RED

cfircav8r

My Feedback: (1)

Have you tried stalls at idle (up high of course)? If you can stall it at a slow speed without climbing then it will slow down for landing. You may just need to bleed off the speed sooner, it is a slick plane after all. If it won't stall, with power at idle, without climbing you will need to get a longer, smaller pitch, prop. If it stalls at a higher speed I would look at the balance. The suggested balance point is often a safe starting point and you should have a bit of room to adjust.

Eddym

Maukaonyx, Thanks, I will fly it once more before mixing in elevator to determine if it is pitching up or down. I know what you mean about gear. I have a revolver with a os 55. it is 3 years old and it is on its third set of gear, but it's fun to fly. I fly off of pavement so the combination of that and my skills thier toll.

cfircav8r, I will try the stall test. I balanced it Per the manual using the GP balance machine and it flies great. Untill I get used to it I am paranoid about getting it to slow and stalling durring the turn from base leg to finnal approach. I can tell you that thoughout the approach if I flair or try to pich up to slow down, it will climb. I think I just need to get used to the speed.

Thanks everyone for the help.

cfircav8r

My Feedback: (1)

It is important to learn the stall characteristics so you know how much you can safely slow it down. The easiest way to slow down is in the turns but can be risky if you don't know how it will react. Test it out at altitude and get comfortable with slowing it down. You may find it needs to land fast, but you also may find you can safely slow it down a lot more. Either way you should know before approach and landing. Its a slick plane and needs time or extra loading to slow down, and if you nose down even a little it will gain speed rapidly causing it to balloon again. Practice slow flight and landings will become easy. In the end though a little fast is a lot better than a little slow every time.

Guitarman52

My Feedback: (2)

I have the shoestring with an os 55 on it. It is very hot on landing. I usually just try to bleed off as much speed as I can before landing. Takes practice.. Good Luck

speedracerntrixie

My Feedback: (29)

LOL I always thought it to be a bit of a pudge with a thick, ugly wing. I still think it is CG related. I have no issues slowing down this baby and it is much cleaner then the GP Shoestring.

Oberst

I don't think that's correct. My WWI birds are nose heavy and they fly slow. I have to keep the power up so the plane doesn't drop, but they don't fly fast unless I'm in a power dive.


The Shoestring is a racer so it will fly fast and land hot. Most scale racing planes are for the more advanced flyer. If you think the Shoestring is a little hard, try flying a old style GeeBee R1! OMG!


Pete

speedracerntrixie

My Feedback: (29)

Pete, lets try comparing apples to apples here. You WW1 biplane has a ton of wing area and the drag of a barn so yes it will fly slow and be less affected by CG. The GP Shoestring is NOT a race plane. It is a sport plane patterned after a race plane. With a healthy .60 2 stroke one would be lucky to see 100MPH. It has a thick, slow, forgiving airfoil so in reality it's flight charictatistics will be more on like with a Kaos then that of an actual race airplane. IMO this is what bites guys. They imagine that just because it LOOKS like a race plane it will be less forgiving, so they set it up nose heavy and minimal throw, then it lands fast. Set it up the same way you would a Kaos or Super Sportster and go fly.

HighPlains

My Feedback: (1)

The GP Shoestring is a bit of a pig in terms of wing loading, which does tend to raise landing speeds. The placement of the CG is unimportant as long as you don't run out of elevator authority. But if you can't stall the wing when flying slow in level un-accelerated flight, then you don't have either the CG far enough back or enough control throw. If you can stall the wing in the above flight condition, then it's just poor pilot technique. If landing with power, try flying on the backside of the curve to slow down more.

Pylon racing planes are flown with the CG very far back, and the control throw is minimal - like full up elevator throw of about 1/8" measured at the trailing edge. Landing them is somewhat difficult since dead stick is the norm and the airplane does not have enough throw to recover well from a bounced landing. You can slow a fast rolling airplane in a short distance with a bit of down elevator, assuming the engine is dead and the exhaust system clears. The wing creates a lot of drag when the tail is held high.

Oberst

Wrong. The Shoestring is a racer, and the GP version is a Sport Scale of the original Formula One racing aircraft.

http://www.air-racing-history.com/ai...%20Polecat.htm

All scale aircraft like to be a little nose heavy, some more than others. Depending on the models lift and efficiency wing design determines if the aircrafts stall speed will be higher or lower.

Most designers of racing aircraft want speed, so they have to sacrifice efficiency and as a result the aircraft will loose lift at slower speeds.

Nose weight has nothing to do of the speed of the aircraft unless the aircraft is in a steep dive. The P-47 was the heaviest US Fighter in WWII and far from being the fastest. When pilots had a enemy on their 6', most often they would put their aircraft in a steep dive in order to get away. The P-47 had the fastest dive rate than any other aircraft in WWII.

Because of the design of the wing and high lift and drag of the WWI plane, it will fly slow. I used that as a small comparison. My Sport Scale .90 Extra 260 has a honking 1984 O.S. FS120 (Before Surpass) (Looks like a Saito) and it is nose heavy, but the power of the engine corrects it. My Extra has very little drag and the wing design is very efficient. It's not the nose weight that makes my plane fast, it's the power of the engine, RPM rate, aerodynamic airflow and wing design that determines if the plane is fast or not. Also the size, design and pitch of prop can contribute to higher speed.

Because my Extra has efficient wings, I can land at slower speeds. You don't see people racing Extra or Edges in a Formula One race because these planes were designed for aerobatics and maneuverability, not for speed.

So we disagree to disagree. Unless you have data to back your theory, then I will stick to my statement.


Pete

HighPlains

My Feedback: (1)

What Shawn was saying is the GP model is a sheep in wolf's clothing. It has a sport airfoil and certainly is not very fast. It is about the same size as the models we used to fly in RC Formula One Pylon that went about 170 mph with .40's, but the GP model will never see such speeds unless it is shipped by UPS Air.

Oberst

Understood. But flying it scale we wouldn't be flying it 170 anyway. GP ment it to be somewhat scale, not all out " let's see if we can hit 300mph out of it." So the GP Shoestring we can say IS a semi scale racer for the scale racing class. Correct?

Pete

Lnewqban

Eddy,
Flaperons have been discussed here many times, and in general, they can do more harm than good during landing.
Run a search in the old related threads if interested.

Stall depends on AOA only.
If you stay under that critical AOA for any speed, your plane is safe.
The stall test is to determine and get familiar with the critical AOA that is specific to your airplane.
The problem with tight turns is that you can easily force the AOA above the critical limit by feeding elevator and not seeing the extreme nose up attitude as easily as during straight flight.
A big circle approach will help avoid that base leg-final crisis.

http://masportaviator.com/2004/03/25...ding-approach/

Crabbing the plane during final will slow it down effectively.

Whenever the plane climbs instead of stalling for elevator up input, it is carrying too much energy for that AOA and is flying under the limit AOA.
Again, for any angle under the critical AOA, there is only one speed that allows level flight.
Before touch down, just try to keep it flying at the same level just above ground, while you feed elevator and the speed decreases steadily.

speedracerntrixie

My Feedback: (29)

Pete, to the best of my knowlwdge there is no racing class for this airplane. Even if there were it would not be competitive. Let me attempt to get through to you one more time. This is a SPORT airplane. Again just like a Kaos or a Super sportster. What makes it a sport airplane? Wing airfoil, wing area, tail area. If you actually put any real effort into your reserch, you would have found that GP changed the scale outline quite a bit. They added wing area, wing thickness and tail area. Why would they do that? To make it fly like a SPORTAIRPLANE! No back to answering the OP's question again now that we have him confused. Move the CG back 1/4" at a time until it does land slower. I am betting that after pulling the power back a fair amount of back stick is required to keep it level?

hugger-4641

My Feedback: (6)

He said that it climbs even at idle if he feeds in elevator to try to flair. This tells me he needs to check the idle speed of his engine. Depending on this he may need to  go down a little in prop pitch or possibly even up in diameter. He didn't say but I'm betting he is running at least a 14x8. If his idle speed is correct, going down in pitch will help. If his idle speed is too high and he can't adjust it any lower, then going up in diameter will help.

speedracerntrixie

My Feedback: (29)

To be honest, anyone having trouble landing an airplane because it won't slow down is going to check his idle speed as step 1. It's possible he could be running too much pitch but even that can be corrected with proper technique. I've landed 40% aerobats running 170cc engines and 32X10 props on 300' runways with room to spare. You need to start slowing the airplane soon, not drop a bunch of altitude on base and final and keep a positive AOA. IMO the keyboard pilots have the poor guy afraid of slowing it down because it's a "RACE"plane LOL

Pylonracr

I have a fast plane that likes to land hot, and a short runway to do it on. Bring it in on al long, low final. Add enough power to make the runway, and when you are close enough to make the end, cut the power BACK to idle and set it down.

If this plane really likes to land hot, or if you are afraid of it, start short and use power to make the runway. When you take away the power, it will slow down.

hugger-4641

My Feedback: (6)

You could be right, he doesn't say how is making his approach. If he's trying to glide in like a high wing trainer and then flair, he's not going to be able to get it down. But if he is coming in low and slow and still can't get anose up AOA without climbing, thenhe's gonna have to do something to get some prop braking to help.

jaka

Hi!
During my years in this hoby /sport I have seen many people that don't care to trim their aircraft. They put the C of G at the the point the plans tell and just leave it there. That's it!
This is not the way of doing it if you want to have a good flying airplane.
You must be prepared to move the C of G around slightly to obtain the best flying caracteristics for just that particular plane.

Here is how to trim an airplane.

1. First checking the C of G!
Fly the plane and att high altitude fly straight against the wind and throttle down to idle. The idle should be so low (at around 2000-2500rpm for most glow engines) that the airplane more or less can stand still in the air. Now! Notice how the plane reacts when you apply more and more elevator to hold the nose high. You should be able to hold the plane with its nose high or at least level without the nose dropping!
This is very important! The nose should not... I repeat, should not drop at all! If it does the plane is too nose heavy!

2. Second check for correct nose heavyness.
Fly at att full speed and make a sharp (level) pylonturn (Just using ailerons and elevator, as usuall ). Notice how the plane behaves! If it drops the nose slightly its too nose heavy! Goal is to have the plane seeping trough the turn as if on rails without doing anything but the initial aileron and elevator command.


3.What to strive for when it come to setting up an airplane.
Always trim an airplane at full power! It should fly straight as an arrow!
Always strive for to have the C of G as far back as possible without loosing good flight caracteristics.
Always strive for as small elevator trows as possible and be prepared to minimize it when moving the C of G rearward (the other way around when moving the C of G forward).
Always strive to build light and knowing that light weight is the fundamental goal to acheive if you want agood flying model airplane.

The Great Planes "Shoestring" it's just a sportplane it is able to fly slowly and land rather slow if you just trim it right.

maukaonyx

I added lead in the tail to get the CG per the manual on this plane. I still have another 1 cm back that I can move it, so I am adding another ounce of lead to move the CG back but still remain in that 1 cm range. We'll see if it really helps the landing speed, and I will post again after trying that. Doing so has helped on other of my planes, and I hope it works on this one. Jon

Bozarth

My Feedback: (15)

The OP should trim his elevator so the plane maintains altitude at a slower airspeed (normally at a reduced power setting). Most planes that "like to land hot" don't know any better until one re-trims them for a slower airspeed.

If you trim your elevator for level flight when you are buzzing around at 60 mph with full power, when you pull the power back to land, the elevator will still be telling the plane to go 60 mph. Establishing a stabilized approach will be a bear! Pull the power back to something reasonable and re-trim the elevator to maintain altitude - the plane will now fly slower. How slow? You decide.

Ask a full scale pilot how often he changes the elevator trim during a routine flight (F-16s don't count). Then ask an RC pilot how often he does.

Kurt

cfircav8r

My Feedback: (1)

As far as telling if its nose heavy using a steep turn and seeing if the nose drops has nothing to do with nose heavieness. It is purely a function of lift. When I said it is a slick plane that has nothing to do with top speed, it has quite a bit less parasitic drag than your average sport plane so will be a little harder to slow down. As for being afraid of turns, you should always be careful of turns until you learn how it reacts to varying degrees of bank while maintaining altitude. Yes learn to use trim, find a good safe slow speed and trim for it for landing. this will allow you to make a good stable approach. Unless you are very confident in your engine I would avoid dragging it in with power.