I could really use some help.
 

I am new to flying gliders. I have flown RC sport planes and Control line for years but sailplanes are new to me and I have to admit I really am getting into it. What I need help with is the electric part. For instance, If I build a 2 meter glider such as a Gently Lady and want to put an electric motor, ESC, battery, receiver and servos in the plane, I get lost from the servos up. I do not know what size motor it takes for what size plane and then what battery and ESC and receiver would go with it. I don’t know if you have to measure in volts….etc. Is there any simple way to explain this to a novice like me for the systems that should go in certain size sailplanes. I am not so much worried about which brand, I just need to know from the motor back the sequence and what I should use. I assume that the size of the plane would determine what size motor just like with a nitro engine. I have Futaba radios if that helps.

Any help you can give me to get me started would be greatly appreciated.

Mike

RE: I could really use some help.
 

Hey Mike.

Do you happen to know Liquidity? He's in Byron as well and I just finished up a EP Gentle Lady for him. He seems to be very happy with the flight performance but he supplied the motor and though I know it's a Hacker knock-off I can't tell you where he got it.

I enclosed the motor in the nose, had a 2 cell lipo and the RX behind that and the servos in the stock location. I used mini servos and the balance came out pretty close.

Jeff

RE: I could really use some help.
 

Mike,

A buddy of mine is also very new at flying RC planes. In fact he has only flown one sailplane.

He just purchased the Radian sailplane to take with him to Colorado for the Summer. He bought the RTF one, that you just have to add your own RX and MA lip battery. I have spoken with him since he got out to Colorado, and he has told me that this plane flies fantastic. He spent a lot of time on a buddy box while in Florida for the Winter, but is now flying on his own with the Radian.

This may be a good option for you as well, if you have not already purchased a plane.

Here's the link to Horizon hobbies who carries the Radian. You can also search on RC Universe for some great threads on this plane.

http://www.rcuniverse.com/forum/m_8000175/tm.htm

http://www.horizonhobby.com/Products...ProdID=PKZ4775

I also fly all types of electric planes, from F-14 Tomcat's to Gliders, and I still get a thrill when I am in a good thermal till my neck hurts.

Hope this helps,

Randy

RE: I could really use some help.
 

> EVERYTHING YOU WANTED TO KNOW ABOUT ELECTRIC FLIGHT
> http://www.wattflyer.com/forums/showthread.php?t=31071
> http://www.rcuniverse.com/forum/m_7100376/tm.htm

This is covered in greater length in the threads but here are some quick points:

Volts X Amps = watts, a measure of power

Watts/pound of all up airplane weight is a good starting point.

So, for example, if we estimate that your GL will weight 2 pounds with all gear on board including battery, then we can do a calculation to get an estimate of what size motor would be good.

For casual perfomance, climb out at say 30 degrees, 50 watts/ per pound or 100 watts for a 2 pound plane

For quick climb, say at about 60 degrees, 75 watts/pound or 150 watts for a 2 pound plane

For fast climb, verticle or nearly so, 100 watts/pound or about 200 watts for a 2 pound plane.

More than 100 watts/pound = climb out of sight pretty fast. Perhaps e glider competitions


When looking at motors for sailplanes you wnat to look at motors that favor bigger props. Typically these have kV ratings in the 800 to 1500 range and support props in the 9 to 14" range.

Wider props will give you a better climb.

If you want the details behind what I posted, read the e-book at either of the links above.

RE: I could really use some help.
 

Ive found that you can ask for sugestions on most of the sites that sell electric motors. Medusa is one and heads up rc is another. They even have calculators that you plug your info into and whamo you get the set up you need. But im talking of course about planes that are unknown etc.

RE: I could really use some help.
 

Weight, preferred battery voltage are typically all you need to know. Then you experiement from there.

For example, I use Rimfire motors with very good experience.

The motor calculator is here:
http://www.electrifly.com/config/index.php

I tell it Weight of plane
Max prop diamater - For a 2 M plane let's say 13 inches
What kind of performance - Let's use trainer
It gives me a logical set of battery voltages based on lipo batteries. I will use 11.1V

It spits out 3 choices. I chosse the best thrust options as I am going for good climb rather than high speed.

35-30-950 / GPMG4590, 11.1 V, 10X4.5 prop with a 35 amp ESC and a 1250 or larger battery. :D About 100 watts per pound.

I can adjust my inputs from there.

Based on that battery, I should get about 4 minutes max throttle run time. With each climb of about 30 seconds, that should give me 6 climbs with reserve power in case I need some help from the motor to get home.

I would probably bump it to 2100 mah pack and which should give me 6.7 minuts of run. That would give me 12 climbs with some reserve.


I can go back and change it to a 2 cell lipo.

Now it recommends a Rimfire 28-30-1450 / GPMG4570, - Same prop and same battery capcity as minimum. This will give 3 minuts. Again I would bump up to 2100 mah pack size for 5 minutes of run time. That is about 8 climbs with reserve powe.

The benefit of the 2 cell set-up is that it is lighter. It is not quite as powerful at 86 watts/pound buit More than enough to give me a quick climb to soaring height, but not quote verticle. Maybe 75 degrees climb angle.


And that is how you do it.

RE: I could really use some help.
 

Hi Guys,

I had to use a CG calculator program to determine the CG of a sailplane that was given to me. It has a wingspan of 8'2" and has ailerons. I plugged in all the dimensions that the program called for, and it came up with all kinds of info.

It said the Neutral Point was 4.7" from the root leading edge, and the CG was 4.37" from the leading edge with a Static Margin of 5%
with a static margin of 10% the CG was 4.03" from LE, with a static margin of 15% the CG was 3.7" from the leading edge.

OK, so the question is if the Neutral point is always 4.7" from the root leading edge, does that mean that with all gear in place, if I put two pencil erasers at this Neutral point the plane will sit perfectly balanced with no tip forward or back?

If this is correct then I am in business, as the plane does sit perfectly when I balance at this Neutral point.

Thanks for any input.

Randy

RE: I could really use some help.
 

Nope

The CG is where the plane balances perfectly with no tipping.

The neutral point is where the pitching moments of the wing and the pitching forces from the horizontal tail match each other. It doesn't move because the wing and the h.tail don't change their area, span, chord, (all those measurements you entered into that CG computation) etc whereas the CG can be easily moved fore/aft by moving things within the fuselage or do things like burn off fuel.

When you've got those two pencil erasers (or your fingers) directly under the CG, half the weight of the plane is fore and half aft, and the sucker will be perfectly balanced.

RE: I could really use some help.
 

Da Rock is right. Trick is to get the CG where you want it. The CG given by the plans or the instructions is the best place to start.

RE: I could really use some help.
 

da Rock & AEAjr,

Thanks for that explanation. It helped me to understand this CG/neutral point. I got it that the NP never changes, as was obvious to me when I was using the CG calc program and changing the Static margin from one value to another.

The program states that the Static margin should be between 5-15% for good stability, and that a low static margin gives less static stability, but greater elevator authority, and a higher static margin gives greater static stability, but reduces elevator authority.

I think I even get that :)

Most of my military and sport type planes I have set up a tad nose heavy, and they fly very good.

I have one sailplane the Glass Air that I have been flying for years, and it is also set up a tad nose heavy. I think it flies well, and I can thermal for long periods with no problem. Question is, am I doing this right, or should I try and go to a more balanced sailplane?

I am no expert as you can tell, but I do have a lot of time under my belt with my Glass Air. If I can make the plane fly better or make me look better, then I am all for it :)

Getting back to this Static Margin. The program says between 5-15%, so I was using the middle of the road as a starting point.
Thus using the 10% figure it gives the Cg at 4.03" back from the LE. OK, so I mark that point on the wing and try to arrange things or add nose weight or tail weight to get the plane to balance perfectly level or slightly nose heavy.

Which way should I go for a start?

RE: I could really use some help.
 

When you've got the CG within the safe range, you've got a safe handling model. "Safer" is subjective. In fact, the extra safety is mostly in your mind when you're biasing the CG just a bit more noseheavy. With the CG in the safe range, your elevator response will almost certainly be adequate and about all that changes is how fast the pitch changes with elevator movement. And if you're even a halfway decent pilot, you will be fast enough to deal with it wherever it is.

What you actually gain from having the CG closer to the NP is a more efficient glider. And the difference in efficiency isn't something that slams you in the face, it's more apt to just rustle your hair. It's hard for us humans to notice that our glider stays up a little longer or gets up the towline a bit quicker. Efficiency is what wins contests by small margins, not huge crushing thumps, that is when you're comparing a 5% SM to a 10%. And you might not get it unless you also tune your elevator throws a bit to match. The better efficiency might be there but you're still slamming the TX stick like before and overflying. Matter of fact, you need to pay attention to your elevator throws when changing CG.... in either direction.

Move the CG forward and you do lose efficiency, and you might need more max elevator throw.
Move the CG aft and you gain efficiency, and you probably will gain even more if you tailor the elevator throw to the new effectiveness. (Or at least not lose what you've gained.)

The CG/elevator throw is one of those deals where experience comes into play. Good thing about our hobby is that it's so wonderfully easy to test stuff. And the even more wonderful thing is that it's so hard to see that stuff clearly that we can decide without breaking a sweat that whatever we do, it helped..... grin.

RE: I could really use some help.
 

If your CG is already within that range, go aft. Truth is, I always go aft. I've never had a glider that I wanted to be less efficient. And never had one with a CG that made the glider scary to fly if I tuned the elevator throw if it needed it.

Remember that most reputable glider designs list a CG start point and elevator throw to match. Start from those two and the sucker's going to be safe to fly. If you do move the CG aft remember that the sucker MIGHT be quicker on the stick on pitch. And if you don't like the quickness or want to insure your hamhanded flying doesn't cost you some of the improved efficiency, then tune the throw some. Moving the pushrod out one hole on the elevator horn usually works like gangbusters.

RE: I could really use some help.
 

da Rock,

Thanks so much for all your great explanations. I see that what I have been doing so far with my sailplanes have been a good starting point. Now to refine the performance with some trial and error. I should be able to handle the plane with no problems.

I am in Laurel Springs, NC, not far from the Lump (slope soaring site)MM 265 on the Blue Ridge Pkwy. Are you near there, or further west?

I have flown the Lump a couple of times, but not with a pure sloper yet. I still feel the need for power in my sailplanes :)

I have a small Fling ( high start ) plane that I plan to take out there soon. That plane I will risk loosing.

Thanks again for all your time. I will post my results of the maiden.

I just went back to some of my previous posts, and saw that we have chatted a bit last Summer when I was looking for sites to slope.
I see that you are very familiar with the slope.


OK, so next questions is, do you ever get out there? I would love to meet up with some real knowable slopers.

Randy

RE: I could really use some help.
 

Flying the Lump with a pure sloper is... hmmmm.... well........ The Lump actually isn't really a slope site except from the direction of the parking lot and the mountain just the other side of that lot pretty much cancels out that direction for sloping. And going off the sides of the Lump where the wind comes from has you looking into trees you can't see beyond. I've never considered taking a pure sloper up there. About the only sky you can see to fly in is above the trees and they're at your altitude. The couple of times I've been, I've taken regular thermal birds. Sagitta II and Oly. I took a Siren once, which is about as close to a sloper as I got, and wound up busting it... actually, wiping it out. Launching off the top of the Lump at the time put the Siren up into backwash off the trees that're out on the slope proper and my launch went right into boiling wind. ............. I'm not sure that a pure sloper is going to be much at home up there.

The guys who used to go up there that I went with have pretty much wandered off, mostly doing some fishing nowadays....

I think it'd be worthwhile (if you lived up there) to scout around for something like Max Patch. A bald that you could get on would be a better slope than the Lump, that is, if it had just a little width. I've driven around some up there looking, but really didn't have time nor knowledge of the backroads.

RE: I could really use some help.
 

I fly the Lump quite a bit and most always with pure gliders. Sometimes I may take a powered glider to test the waters before a launch over the trees. I've flown mostly smaller type slope ships I flew in California, 40-60" but I do have a new 3.2 meter moldie to try out when ever the wind is right. Any wind with south in it's name at 10mph or more is good there. You can call the Wilksboro airport for recorded wind info. 336-696-3788.

RE: I could really use some help.
 

Or if you want the forecast for the next 3 days for Wilkes County Airport, including the wind speed and direction, you can just click this:

http://www.usairnet.com/cgi-bin/laun...=KUKF&state=NC

RE: I could really use some help.
 

da Rock,

Good info on the Lump. I guess I don't know a slope from a mountain top :)

Evan,

If you are ever heading to the Lump, shoot me an email and I will meet you there. I love to learn new tricks.

RE: I could really use some help.
 

I'll do that. Matter of fact, I'll talk up a trip at the clubs where I fly to see if any glider guys want to go and when. The more the merrier.

The Lump actually works as dependably as it does because of slope lift. So it really is a slope. Unfortunately, the trees that come all the way up it's slopes on the working faces take away a lot of the kind of flying you can do on a slope. At most good slopes, the flyer stands right at the edge and looks out and down. Most of the time your glider's position is about your own altitude. It can be higher of course, and will often be lower but those times the sucker is out in front of you. When you bring it in to land, you usually won't bring it very high above you or very far back off the slope, because of the curl. At the Lump, we're standing back from the trees that define the face, back where the curl is a lot of the time. When I moved back home here, I looked around for glider flyers for a couple of years and couldn't find any. When I finally found a couple they mentioned the Lump as a perfect slope site. They'd never been sloping anywhere else. Heck, all we got are worn down mountains completely covered with trees. Beautiful country, but not really slope country.

RE: I could really use some help.
 

THE NEW GLIDER PILOT'S HANDBOOK
Second Edition
by Ed Anderson

If you are just getting started in thermal duration gliders in any form, then there are many things you will want to know. The New Glider Pilot's Handbook is here to try and make that easier.

In the first edition of the New Glider Pilot's Handbook, I compiled the resources based on a series of articles I wrote for RCEzine.com. Unfortunately the magazine went under so the info is no longer available. I have rewritten much of the material and posted it in a variety of places around the forums.

This is a compilation of many of those articles and threads. While many of the articles are mine, I have included some excellent work by other authors. Also, I have provided links that go to various forums and locations so the new glider pilot can discover the breadth of on-line resources that are available. The articles are rich with links to other resources as well, so this listing is deceptive. There is much more behind the links than you might expect.

Some of the links go to threads that I started when I had a question. I felt the content of those threads was helpful, so I have included them here as resources. Have you ever sat in a class hopeful that someone else will ask the question that you don't want to ask? Well, I asked for you. Take a look at the responses.

I invite other pilots to contribute to the thread to expand and supplement what I have compiled here. I invite those with questions to post them in this thread or one of the threads referenced below. The only dumb question is the one you don't ask.

To new and experienced flyers alike, I hope you find something here that will be useful and will contribute to your soaring experience.

=============================================

GETTING STARTED

Getting Started with Gliders
http://forums.flyesl.com/topic.asp?TOPIC_ID=217

Sailplane terms
http://www.rcgroups.com/forums/showthread.php?t=185385

Sailplanes are Wonderful!
http://www.*********.com/forums/show...t=5356Pop-Offs

Discus Launched Gliders
http://forums.flyesl.com/topic.asp?TOPIC_ID=230

Why Join a Club?
http://forums.flyesl.com/topic.asp?TOPIC_ID=238

Welcome to the Novice Lounge
http://forums.flyesl.com/topic.asp?TOPIC_ID=224

Other Pilot's Recommendations for First Sailplanes
http://www.rcgroups.com/forums/showthread.php?t=211753

Soaring Clubs
http://www.rcsoaring.com/


TIPS

Learning to Use a Hi-Start
http://forums.flyesl.com/topic.asp?TOPIC_ID=216

What do Thermals Look Like?
http://www.flyaboveall.com/mountainp...rmalclinic.htm

Detecting Thermals
http://f4bscale.worldonline.co.uk/Thermals.htm

Plane Locators
http://forums.flyesl.com/topic.asp?TOPIC_ID=237

Tuning Your Glider's Elevator
http://www.youtube.com/watch?v=Rz0SqTPv3PQ

Performance Tuning Gliders
http://forums.flyesl.com/topic.asp?TOPIC_ID=227

Using Ballast
http://forums.flyesl.com/topic.asp?TOPIC_ID=232

Test Flight Procedures
http://forums.flyesl.com/topic.asp?TOPIC_ID=226

Video of a hand throw - test glide
http://www.youtube.com/watch?v=ixwur...eature=related

Workshop Ventilation
http://forums.flyesl.com/topic.asp?TOPIC_ID=235

CG Location
http://polecataero.com/articles/cg-location

Using the Rudder in Thermal Flying
http://www.polecataero.com/articles/...hermal-flying/

Getting Planes out of trees
http://forums.flyesl.com/topic.asp?TOPIC_ID=239

Sample Set-up for a Full House Glider
http://forums.flyesl.com/topic.asp?TOPIC_ID=233

Weather - Knowing When to Fly
http://forums.flyesl.com/topic.asp?TOPIC_ID=236

Contest Strategies
http://www.rcgroups.com/forums/showthread.php?t=265089

Timing the Zoom
http://www.youtube.com/watch?v=bSDmYwbMxZo

Reference to various types of soaring
http://en.wikipedia.org/wiki/Radio-c...orms_of_flight




RADIOS

Choosing a Sailplane Radio - What to Consider
http://forums.flyesl.com/topic.asp?TOPIC_ID=223

First Time Servo Set-up
http://forums.flyesl.com/topic.asp?TOPIC_ID=248

What Goes on Which Stick
http://forums.flyesl.com/topic.asp?TOPIC_ID=234

Range Checks
http://www.*********.com/forums/showthread.php?t=7753

EPA/ATV
http://forums.flyesl.com/topic.asp?TOPIC_ID=247

Dual Rates and Exponential Compared and Explained
http://forums.flyesl.com/topic.asp?TOPIC_ID=249


THE JOY OF SOARING

Trying to explain the thrill of gliders to friends
http://www.rcgroups.com/forums/showthread.php?t=175969

The Joy of the Hunt
http://forums.flyesl.com/topic.asp?TOPIC_ID=225

Soaring is more fun with friends
http://forums.flyesl.com/topic.asp?TOPIC_ID=228

Follow me, silently, and I'll show you where there's lift! :)

RE: I could really use some help.
 

I agree, I moved here after living in L.A. near Ventura, San Diego, Spain, which has some of the best spots in Europe, and Guam which had some great spots. (I'm retired Navy) and it drove me nuts that we have all these mountains and no good slope site. The best I've found is the Lump and you can toss it out between trees but I use a short bungie. And yes you don't get any of the in your face flying like the good places.

But we get what we get. I do have a sloper that breaks down for travel and I get it to the good places now and then since I travel alot.


Randy, no guarantees. Plus you'll need a tow hook on your planes.... Slpoers with tow hooks......

RE: I could really use some help.
 

I use weather.com to get 10 days out and the phone number to get the right now wind...

Thanks.

RE: I could really use some help.
 

da Rock & Evan,

I see what you guys mean about the trees. The first trip I made out there, I thought this is going to be scary. I have watched a lot of slope video's, and even bought that DVD with the guy doing like 186mph. I think they call it dynamic soaring or something.

All the slopes in those videos, were like you say, treeless slopes.

I only have three sailplanes, and two of them are electric. I know, I know, that's cheating :)

My only pure glider is the little Fling, but I need to get a new surge tube, as it rotted.

I am pretty much available all the time, so if you guys can put together a date for a few guys to meet up, that would be awesome.

I was Navy also, retired too, but not from the Navy. Just proud to have served. I was in 1971-75 Vietnam vet.

AeaJr,

That is some great stuff you posted links too. I will be exploring a lot of them. I could have used the one on retreiving planes from trees a couple of weeks ago. :)

RE: I could really use some help.
 

The Fling is great and they sell the matching high start at Tower but I use the standard full size one from Dynaflite.

http://www3.towerhobbies.com/cgi-bin...&I=LXE635&P=ML

The big problem with the Lump is the wind is seldom good. The LZ is fantastic, nice green park grass...

RE: I could really use some help.
 

Evan,

Tower's price seems a bit pricey on that high start. I think I will have to find a surge tube supply.

RE: I could really use some help.
 

Just got back from the maiden flight of the big sailplane. After all that figuring of the CG etc, it seems that it was way too tail heavy after all. I'm not sure how that could be with the plane balancing perfectly at the spot the calc program said, but it was.

It acted just like my old Glass Air when I first got it and it was too tail heavy. I gave it about 1/2 throttle and tossed her into the wind.
She was trying to go straight up. I applied some down, and it was responding, but as soon as I let off on the elevator, she would head up again. I gave it more throttle and more down to get it to level off a bit. It was very squirrelly, so I did all I could to get her back on the ground. It was more luck than skill but she belly landed rather hard, and broke the fuse in some places that were already repaired. Broke the prop of course, but ever thing important is fine.

I will just do a quickie repair to the fuse, and add some more nose weight for the next flight, maybe tomorrow weather permitting.

Not sure why the calc program gave that spot, but I inputed the dimensions the best I could.

Oh well, maybe the next maiden will go better.