lyk2fly

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Hi all,
I have a Hangar 9 Aspire ep. It flies ok in calm wind but is very hard to fly in 5+ mph winds. Will ballast help? If so how much should I use?
Thanx,
Mark

slopemeno

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Possibly. With balsa planes the trade-off is the higher landing speeds, and the greater chance of damage- But it will penetrate better.

Something to keep in mind is that lots of balsa floaters have excesive decalage, i.e- the leading edge of the wing is too "positive". Something that might work is moving the CG back slightly, and adding a small shim under the trailing edge of the wing. The way to test if youve got the CG/Decalage issue nailed is to dive the plane, and see if it pulls out (too nose heavy, too much decalage), or it "bunts" (dives more than your input- its too nose light or insuffucent decalage), or it maintains the dive angle you placed it in( juust right, IMHO). This would be a good time to reduce your elevator rates too.

Now, keep in mind you can't dive it too long because you'll probably fold or flutter the wings. The changes will help your plane fly faster and react to lift better. You can still ballast it if you want to though. You can make ballast plates from roofing flash and have a system where you can adjust the amount of ballast you use. I would probably add weight in 4 oz stages.

You should check out some slope racers ballast systems out. They have a"shotgun" style system where you pull the nosecone off, and add ballast slugs like loading a pump shotgun-very slick. You can add wooden plugs the same size as the lead slugs to vary how much weight you carry, so if your system carried 5 slugs, you could load 1 lead, 1 wood, 1 lead, 1 wood, 1 lead. Your CG would stay exactly the same, just your wingloading changes.

rscarawa

Since you have the extra battery and motor weight in your plane, you should not have a need for any significant ballast.

ONe other thing to remember, I tend to think that sailplane pilots tend to fly too slow. How fast are you going when you are hands off as compared to your stall speed? When you fly hands off, are you close to stall speed? I notice that my general thermalling improves when I fly around 2x stall speed. I trim the elevator to make the plane fly this speed hands off. That should be plenty of speed for you to penetrate a 5 mph wind. This is how I fly my Spirit 2m with motor. It is easier to thermal than my nonpowered Spirit that is 10 oz lighter. The only thing I have to watch for is how much elevator I use in turns on the EP version.

lyk2fly

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Thanks for the replies,
I have managed to get flat tire weights and have arranged them in 3 oz. clusters. They fit perfectly under the battery tray and I have a foam bed under them to protect the fuse and hold them in place. I cannot fly today due to 20 mph winds from this storm that the east is experiencing, so I'll try them out asap. Scot...you probably have something there...I am a newbie to fixed wing flight and I might be flying very close to stall speed. Most of the mishaps occur when I'm circling at low altitude on my landing approach. The wind slows the plane as I approach and the plane tips one wing and down I go. I can land without incident if there is no wind. Next time I fly I will trim the elevator to keep the nose more level and see if this helps.
Thanks again,
Mark

rscarawa

One of the primary rules of sailplane flight is that you use the elevator trim to control speed. Sometimes when penetrating a strong wind, you will need to push the elev trim forward a few notches.

I had a situation a few weeks ago with my Spirit where I had to penetrate a 10+ mph wind. I was flying over a treed area and needed to make about 500' of forward progress to make it back to the tree line. With it trimmed somewhere between min sink and best glide ratio, I could see the plane sinking to the tops of trees (I was not going to make it at my current speed). Before turning on the motor again, I gave her 4 clicks of down trim. From that point, the plane stopped sinking to the trees and started to move forward fast enough that I could tell that I would make it back.

The point being is there is a time to fly slow and a time to fly fast. Most times flying fast is better than flying slow. Think about how your glide ratio changes with the same head wind. If you are flying 15 mph trying to penetrate a 15mph head wind, your forward glide ratio is 0. But if you trim down to 25 mph, then you are making 10mph gain and your glide ratio has improved much over the previous scenario. This is the beauty of gliding. There are so many variables.

lyk2fly

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Scot,
Being a newbie I might not grasp glide ratio and min. sink....is there a rule of thumb designed for a simple mind like mine? For instance trimming for nose level or nose slightly down? In time as I learn the habits of the Aspire I'm sure I'll know my glide ratio and sink rate better. I have flown helis for years but they don't have to move forward to stay aloft....so I guess my Aspire won't hover? Anyway there's just something wonderful about a glider aloft.....just floating around....and I can see that there is alot to learn about soaring.
Mark

rscarawa

Well, when you trim your sailplane and the wind is calm it should alway be in a slightly nose down position. Since you have no motor (or atleast not supposed to use it), the plane generates its speed by falling thru the air column. Speed is regulated by the elevator. People think the elevator is used to control up and down. This is not the right way to think of it. It is a speed controller.

In full scale soaring there are 4 speeds that you need to be aware of. The first is stall speed. When you go below this speed, the plane stops flying. Flight at this speed produces alot of induced drag due to the high angle of attack the wing has to have to maintain flight. Any little elevator, aileron or rudder interruption at this speed can push you into a stall. The plane stalls when the max angle of attack gets exceeded. This is usually about 15 degrees relative to the apparent wind.

The second speed is minimum sink. This is the speed at which the vertical component of your speed is the lowest. As a general rule, it is about 1.5x your stall speed. When you hit lift and want to thermal, this is the speed you want to fly.

The third speed is best glide ratio. IN calm conditions, this speed will give you the farthest horizontal movement for each foot you are off the ground. You should use this speed or faster when going between thermals, landing, or pentrating head winds. THis speed will be about 1.75x stall speed and produces the lowest total drag. Keep in mind, there are two type of drag, induced and parasitic. Induced is the drag resulting from lift. Parasitic is produced from movement in the air. As speed increases, parasitic drag increases, and induced drag decreases. Another way to think of it is like a boat accelerating from a stop. The largest drag to be over come is just getting up on a plan (induced). After this point, the drag to keep the boat up reduces. As you speed up parasitic drag limits your top speed.

The fourth speed is the never exceed speed. This is the speed that when exceeded can cause the structure of the plane to fail in rough wind. Basically, do not point the plane straight down. If you need to lose alt, put her in a spin. THis is much easier on the airframe.

There are more speeds than this, but these are the most important to you. I hope this helps. Happy soaring!

lyk2fly

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Thanks Scot,
That's a lot of info and a lot of help! A thread today over at RCG's is on this same subject BTW. I am going to start paying attention to my elevator trim more...to keep the plane moving a little faster...and as you said I may not need so much ballast. Spring time in Appalachia doesn't bring much calm wind!!! So I have to learn to fly in it.
Thanks,
Mark

rscarawa

Remember that sometimes wind is an indicator of an active atmosphere. Plus if you are near the mountains, maybe you can take advantage of slope lift. You may want to research that.

lyk2fly

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We are just south of the Smokies. The land is a combo of small fields, hills and mountains. I fly in approx. 15 acres of field surrounded by hills on all sides. I imagine that this plays havoc on wind currents. I've only read about thermal flying...haven't read anything about slope soaring yet. I assume that slope gliders are heavier than thermal gliders? Anyway I hope this storm moves away and things calm down....I've got to fly!!!
Mark

lyk2fly

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Finally the wind calmed some and I tried ballast (3oz and heavier battery) as well as more down elevator. I can't get used to the speed!!! The plane eats the 15 acre field up during landing....it even climbed 6 ft or so suddenly during one landing (themal or gust?)....it was within 10 feet of the ground! I did get it down that time without incidence but other times were not so good. The Aspire is a pretty plane but it needs some way of slowing down during landing...spoilers or something. Has anybody added spoilers to a prebuilt wing? Or is a plane already equipped with spoilers a better way to go? Any ideas?
Thanks,
Mark

rscarawa

I do not think you need the ballast any more since you are trimming faster now. That may make your landings easier.

ONe thing you can try if you have the altitude is if you know you are too too high, try a stall or two with the wings level. Pull back so that the fuse is pointing up about 10-20 degrees at the most. When at that attitude, then let the plane slow down to a stall. At the point it stalls let the nose drop by letting the elevator stay in neutral position. YOu should lose about 5-15 feet per stall if done right. If you are ballasted, it will lose more alt. Give it a try at maybe 100 feet for practice.

lyk2fly

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Thanks Scot,
I usually practice my stalls at about 15-20ft altitude [X(] Just kidding....I will try to practice stalls at flying altitude (they scare me). There are lots of things I need to practice...to learn the flying characteristics of the Aspire. I do know that when you're trying to land it will float forever!

rscarawa

Just remember to let go of the elevator when it starts to stall. If it drops a wing in your practice, then you either entered the stall with a wing low or you may have had the nose too high. Also remember that when doing this, it may be better to circle around if you are still very high. If I am at tree top height, I might choose a circle instead of a stall. It just depends.

Take care.

lyk2fly

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OK...things are much better....even without any ballast in winds to 10mph. I'm now using a mix to lower the elevator slightly (8%) when lowering throttle. Landings are better and stalling has stopped. Scot....about practicing stalls....if a wing drops is the correction the same as a normal stall....just let go of the controls until the plane recovers? I need to know before I try this at altitude.
Thanks,
Mark

rscarawa

Stall recovery can be just letting go of the controls as long as you are not tail heavy. If it keeps spinning, you may need to use opposite rudder to stop the spin and get the slow wing flying again. The Aspire should be a gentle stalling plane anyway so practice at about 100' and do not worry too much.

Hope this helps