Todd_J

My Feedback: (-1)

Hi All,

I bought a Slow Stick with a 400 motor (didn't know to look for a difference between it and the 300 version) and a 900mAh battery back, mini servos, and a standard sized JR RC770 RX.

Anyways I'm having a few problems trimming it out. I have to give it 30% forwardstick to keep her from having too much AOA during power on at 75% throttle. But when I power it off, I have to give it full backstick for it to glide (if it doesn't start porposing first). I'm a newbie so I asked a buddy who has flown his SS for a while (he has the 300 version and mini everything, so his overall plane is alot lighter), and he thinks I should move my wing back from the 95mm value twoard the 105mm mark. I think I need to move it forward to about 90mm. My buddy says that getting the CG exactly right is critical before trying to get the trims set. How would you proceed? Move it back or forward. I think I'd rather be nose heavy than tail heavy?

My other question is in slowing her down. How can I go about slowing down my SS airspeed? I watch my buddies, and his almost floats in for landings. True his is the 300 and therefore lighter and doesn't build-up or need as much airspeed. If I put a smaller prop on it would that slow it down? What about a tri-prop? And how would I know if I went too far in slowing it down. My main reason for slowing it down is to increase flight duration times, but i'd also like to have softer landings. Would going to EXPO on my TX be a possible option?

Thanks for whatever help you can give, Todd

wreck_em_all

Todd,

Your buddy is absolutely correct. Getting the CG is critical. Here is what works for me. Mark a line on each wing panel bottom close to the center rib that is 1/3 of the wing's chord back from the leading edge. This is the balance point for your SS. Support the plane with your fingers on the wing marks from underneath. Your goal is to have the fuse as level as possible. If the nose goes up the plane is tail heavy - move the wing backward or adjust battery position to get a level balance. Of course, if the nose goes down it is nose heavy. Move the wing or battery forward. When the fuse balances nice and level test glide the plane, preferably in tall grass. If the glide does not follow a nice gradual doward slope, adjust your transmitter elevator trim to smooth out the glide path. Read the SS manual on this subject again - it is good advice.

There are 2 methods of changing an airplanes altitude. The cotrol surfaces and the throttle. High throttle causes the plane to go up and low throttle allows the plane to go down. You may be using too much throttle on take off. As for slowing down on landing approach a stall by a little nose up and decrease throttle, but not so the nose drops.

Time Pilot

Other than making sure you have the CG correct, I'm wondering if you have enough throw on the Elevator. The behaviour of the SS seems normal, needing down when you throttle up and up to glide.

When you add weight to a plane, the speed at which it stalls increases. You should still be able to fly it fairly slow although flying really slow isn't always the most efficient speed.

Matt Kirsch

My Feedback: (21)

Yes, it's normal for a plane of this kind of design to climb like a monkey under high power. As speed increases, lift increases with the highly undercambered airfoil. There's no way around it, except to reduce throttle, or add down elevator.

Yes, CG is critical. Have you balanced the plane, and if not, why not? You're flirting with disaster; a nose heavy plane flies poorly, and a tail heavy plane flies once ALWAYS ALWAYS ALWAYS make sure your plane balances at the recommended spot on the wing before you even think about flying it for the first time.

Here's where my take differs from the others (I think): The behaviour you describe, that is, the plane "running out of elevator" in a glide, and not slowing down well is a sure sign of the plane being drastically NOSE HEAVY. Balance the plane at the recommended spot on the wing first, then fly it.

The parts to reduce the plane's weight are fairly inexpensive. You need a GWS EPS350C-C gearbox, a prop, and a 7-cell 600-750mAh NiMH pack of some sort (I recommend cheapbatterypacks.com's CBP650 or CBP750 cells). All of this might run you $35 or so, and will knock a few ounces off the plane.

Todd_J

My Feedback: (-1)

Thanks guys for your help!

Well it sounds like from what you all have said that it agrees with what my buddy says, and that is to move it back from the 95mm mark closer to the 105mm mark. Then maybe I'll also change the throttle control from linear to exponential, so that I don't over throttle it and use up my battery.

Given that I can't have neutral stick under both climbing and gliding, do you all suggest I trim for neutral stick on gliding, this would seem to make more sense to me, but I'm a newbie???

One other question, I've crashed her a couple times - duh, I'm a newbie. So she's got one wing tip's trailing edge slightly higher than the other's by about 1 inch. This causes her to turn better in one direction than the other. She likes to go to the left. I was thinking of adding a big decal to one side of the wing to help me keep my orientation of the plane's attitude correct. And I was thinking to add the big decal to the right side of the wing. Would you all concur?

Ok one other question, what's the difference between the EPS350C-C gearbox and the EPS300C-D gearbox and what prop size would go with each???

Time Pilot

Matt,

Do you think you'd get that drastic pitching up when applying throttle if the SS was really nose heavy?

Todd_j,

How much elevator does the elevator go up and down when you apply full up or down on the TX? If the problem is not the CG, your slow stick will only get 'wilder' as you move the CG back. This I know from experience!

Matt Kirsch

My Feedback: (21)

Actually, I do. As I said, the combination of speed and undercambered wing creates excessive lift. Even nose heavy, with all that power up front, the plane is going to climb like crazy under power.

The question is, do you think you'd get that tendency for the nose to drop when power is removed if the SS was really tail heavy? A tail heavy plane would pitch up when power is removed. A tail heavy plane would have an extra-sensitive elevator control; you wouldn't run out in a power-off glide. A tail heavy plane would slow right down and float when power is removed, not speed up and drop like a stone.

Moving the wing further back would make the plane even more nose heavy, BTW.

GWR

My Feedback: (31)

How about some down thrust to help stop the nose up attitude under power

Glacier Girl

My Feedback: (4)

Or couldn't you mix in down elevator with throttle position?

RussF

My Feedback: (4)

Todd I'm a newby but I'll tell you about my plane anyway. I have a SS 400 with all mini size gear. I use a 1150 7 cell pack and stock 1060 prop. Mine isnt too fast but when I first flew it it seemed quite fast. It needs to go somewhat fast just to stay in the air. You get used to the speed as you fly more and then its seems slow. Anyway I dont have the exact measurements or where my wing is mounted but the front wing mount is about 3-4 inches back from the motor mount. My ESC is mounted in the spot between the front wing mount and the motor. My reciever is mounted on the rear battery mount top. For the SS with the 400 size motor the CG needs to be 3-3/4 back from the leading edge of the wing according to the instructions. I mounted everything up then moved my battery around to adjust CG. I like mine a little nose heavy if not dead on. For take off I've noticed that a tad down elevator is needed to keep a slow climb so I trimmed my radio this way. Mine will float in for landings. I beleive that its just a CG thing and not really a weight issue. Good luck.

Todd_J

My Feedback: (-1)

Bash N Thrash thanks for your reply.

I'm going to play with moving the CG a bit this weekend and see how that effects her. I'm also thinking I might change to a prop with less pitch to slow her down a bit. My buddy has one with the 300 motor and a very light battery pack and his flies noticably slower than mine.

Todd_J

My Feedback: (-1)

Hello Matt,

I think you've hit the nail on the head with the nose heavy/tail heavy issue. But what I'm confused about is your very last statement about ' Moving the wing further back would make the plane even more nose heavy' Are you saying that in keeping all my battery pack and servo mounts and recevier where they currently are and ONLY moving the wing from the 95mm mark twoard the 105mm mark will make the plane more nose heavy???

Also, would you recommend using a lower pitch prop to try and slow her down a bit? I currently have a 10/6 on it. What about using a tri-prop on it?

highpines

Todd.........Please give your measurements in inches not mm and where are you measuring from and to and maybe we can get you alittle closer to the correct C.G.........

Todd_J

My Feedback: (-1)

Sorry about that highpines,

The kit directions gave it in millimeters, so I presumed that millimeters was the suitable descriptor for this kit. The standard conversion fator of 25.5mm/inch yields 3.74 inches, but we'll just call it 3+3/4inches. The kit directions indicated to make this measurement from the leading edge of the wing at the center, so that's the point that I've been refferencing in my thread.

Hopefully this clears up any missunderstanding.

Time Pilot

A plane needs a certain amount of airspeed to fly. Think of all the kites you may have flown in your life. Some of them fly in light winds, some need a stiffer breeze. Same thing with planes. Changing the prop isn't the answer to make it fly slower. If you want it to fly slower, you need to throttle down. If throttling down doesn't make it fly slower (ie, the plane glides down or stalls when you try to fly slow), then you have to make the SS lighter by using lighter components or reevaluating any mods you did to the airframe or fuse that added weight. With these light planes, every ounce you can get rid of helps.

As for the moving the wing back making it nose heavy, think of the CG as the balance point of a teeter totter. Or take a ruler and put a heavy eraser on one end of it and balance the ruler on your finger. There will be more ruler sticking out at the end opposite the eraser. Think of the eraser end as the front of the SS and the other end as the tail. Now move your finger closer to the tail end. The ruler will dip down at the nose. That's why moving the wing back will make the SS more nose heavy. The CG is like where you were balancing the ruler on your finger.

Hope this helps. And sorry Matt, for stealing any of your thunder!

Todd_J

My Feedback: (-1)

THANKS ALL for your help!!!

Here's where I'm at with it now: over the weekend I went to the local R/C Hobby Shop and talked with the head guy there that supposedly knows these planes, and conveyed your all thoughts/postings, and $50 later....

I have a 350 C gear motor on it with an orange 1147 prop (ugly looking prop!!!) and a 1000mAh Li-Poly battery. The weight difference in the plane is amazing! After much tinkering around, I finally got the wing set at the 105mm (4+1/8 inches) mark as the kit's directions indicate for this weight-class of motors.

I haven't had a chance to fly it yet. So I don't know how she'll perform, but it is much much lighter, so it should be much slower in flight too.

The only concern I have is that the back of the 350 C motor packaging indicates that the 1147 prop is outside the range of the 350 C motor's ability. The guy at the R/C hobby shop swore this was the right prop for this motor/battery combo. I don't know, and I didn't want to argue with him???

Time Pilot

You are right. I'd get the 1047 and go from there.

Matt Kirsch

My Feedback: (21)

What VOLTAGE is the LiPoly pack? If he sold you a 3S (11.1V) pack, take that back too. It'll burn out the motor, especially with an 11x4.7 prop.

I really hate to say this, but you have to take a hobby shop owner's advice with a grain of salt. Remember that their primary focus is on the business aspect of the shop. They generally don't have enough time to keep track of all the latest advancements in the hobby, let alone all the possible combinations of equipment.

Todd_J

My Feedback: (-1)

It is a 2cell 7.4 volt 1000mAh LiPoly.

I flew it around last night and had a great time with it on the 1147 prop. It flew sweet! When the LiPoly battery stopped putting out enough juice, I traded it out with my 9.6 volt 900mAh NiMH battery and flew it some more. It of course flew faster with the heavy weight NiMH battery, and I had to trim the plane a bit, but still had a lot of fun.

Need some more HELP:

At the end of the two flights, I plugged the batteries into my charger and charged them up over night, or so I thought??? (I have the Hobbico Quick Field Charger II which allows you to charge two batteries of two differnt types at the same time via two different circuits) I went out this morning to fly and neither of the batteries could put out enough juice to turn the motor, although both of them diplayed the flashing LED indicators indicating they had a good charge. I haven't yet had a chance to put the two batteries on a DMM to check their actual voltage under load, but I'm wondering if I could have burnt up the motor running either of these batteries or the 15 amp ESC?

Steve108

My Feedback: (36)

I doubt you motor is burnt out yet. I flew my slowstick with a 1260 prop and 9.6v/600mAh for 2 or 3 flights and the motor still works. It got extremely hot though.

Now set up a picnic table to takeoff land on! Thats a great way to pass the time. Can be hard on props though.

Steve

Todd_J

My Feedback: (-1)

Well it does appear to be a burnt motor. I put a DMM to the ESC output leads, and gave it juice. The DMM read 8 volts on the 7.4v 1000mAH LiPoly battery and 11 volts on the 9.6v 900 mAH NiMH.

My next question is, which battery pack burnt the motor and why? The last one I flew on was the 9.6v 900 mAH NiMH.

Steve108

My Feedback: (36)

I'd guess the 9.6v one did the deed.

Steve

Time Pilot

Steve108,
You can use a 12x6 on a 300 motor, but not the 350.

Todd_j,
I would say either battery could have toasted the motor. You are pulling too many amps through it either way.

Just curious though: With the 1147, how much throttle do you need to cruise around with your packs?

Steve108

My Feedback: (36)

I think you could slow it down by switching to a D gear motor rather than C and at the same time be easier on the batteries.

Steve

Todd_J

My Feedback: (-1)

While the 1147 flights lasted they sure were SLOW and sweet! Initially at about 2/3 throttle, but then near the end of the battery/motor life (I don't really know which) I had to go to full throttle, but the flights didn't last long (8-10 minutes on the LiPoly and 4-5 on the NiMH).

So I took my SS with a dead 350C motor to the local hobby shop and the guy there said, "Well I guess that 1147 prop was just too much for that motor afterall." He then proceeded to sell me a new 350C motor and 1047 prop, and recommended NOT using the 9.6v 900 mAh NiMH battery. I kind of thought it was cheesy of him not to replace the motor for free when it was his recommendation to use that prop/motor/battery combo, but in his defense, he did NOT tell me it was ok to use the 9.6v 900 mAh NiMH battery, and he did give me a 10% discount.

Anyways, now I'm flying my SS with a 350C a 1047 and 7.4v 1000mAh LiPoly battery. I also have a 0947 prop, but I' think I'll stick with the 1047. I do also have a 1060 prop, but it is one of the skinny profile ones not one of the big fat round profile types. What's a newbie to do/choose I guess that will get answered by how many flights I get out of the motor now.....