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Bunch of questions

Old 08-26-2007, 08:19 PM
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Lip84
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Default Bunch of questions

Alright, I am starting to think about getting a sailplane after wanting one for years and I have a ton of questions:

1. I have always wanted a 2M but am considering something smaller due to my lack of storage and construction space. What would be a good wingspan that would allow easy storage/construction/transport but still have the potential for duration thermaling?

2. How to DLG really work? Can you get them up high enough to catch a thermal? I am interested in DLG's because they tend to be a little smaller.

3. Continuing with DLG's...how do they hold up to the stresses of the launch? Chucking a plane from the wing tip seems like it would put a lot of stress on the airframe.

3. I have a DX7 and am wondering which receiver to use. I am looking at either an AR6200 or AR7000. Both of them are full range and the differences are that the AR6200 is 6 channels, weighs 4 grams less and costs $20 (appx) less than the AR7000. All of these are bonuses but I want to check with old wise men prior to purchasing an AR 6200.

4. What size battery should be used and what type? I have several 3S lipos but I know that they are too heavy for a glider. I was looking at getting anywhere from a 350mAh to 800mAh 2S lipo because I only have lipo charging equipment and they are lighter than nimhs and nicds. I have seen lipos as light as 20grams.

4a. Is there an easy way to figure out the RX and servo draw on the batt to determine batt mAh size? I want to get a sailplane with R/A/E and possible flaps or spoilers at some time in the future and be able to fly for upwards of an hour at a time.


I think this covers the bases for now. Any recommendations on good intermediate sailplanes, either arfs or kits, would be helpful as well. I was originally looking at getting a Gentle Lady or Sophisticated Lady but later changed my mind towards the Kestrel at NESP. It is supposedly good for intermediate to advanced sailing and I like the look of it a lot.

Thanks!

Andrew (lip84)
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Old 08-27-2007, 05:25 PM
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AEAJR
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Originally Posted by Lip84 View Post
Alright, I am starting to think about getting a sailplane after wanting one for years and I have a ton of questions:
I fly pure sailplanes 75% of the time so I might be able to help you. You don't mention electric sailplane but this is wattflyer, so which are you really thinking about. I am going to assume you mean pure sailplanes.

[quote=Lip84;260172] 1. I have always wanted a 2M but am considering something smaller due to my lack of storage and construction space. What would be a good wingspan that would allow easy storage/construction/transport but still have the potential for duration thermaling?

1.6 to 2M sailplanes are great for getting started. Small enough to be easily stored and transported but large enough that you can get them high and some distance out so you can work thermals.

My First sailplane was a Great Planes Spirit 2M RTF. I still have it and still keep it mostly in the box it came in. The tail group sticks out. I rearranged the components after a major crash and got the weight down a bit. The plane flies very nicely. It comes to the field often, especially when I expect light winds.

The Multiplex Easy Glider has become the standard first glider in our club, along. The Spirit is a 3 channel RES plane. The Easy Glider is also three channels, but you need a 4+ channel radio to handle the ailerons.

Originally Posted by Lip84 View Post
2. How to DLG really work? Can you get them up high enough to catch a thermal? I am interested in DLG's because they tend to be a little smaller.
DLG popularity is growing very fast. They are tons of fun. Getting good height is more a function of technique than strength. Many of our pilots fly DLGs and larger winch and hi-start launched gliders. They can be low cost 2 channel kits or they can be expensive 4 channel composites. Either way they are fun.

And yes, you can get them high enough to find thermals. Definately.

Originally Posted by Lip84 View Post
3. Continuing with DLG's...how do they hold up to the stresses of the launch? Chucking a plane from the wing tip seems like it would put a lot of stress on the airframe.
They are designed for this type of flying so they hold up well. Of course if you crash them ..... depends. And, of course, some are stronger than others, but they are built to fly, not crash.

The smaller 30-50" wing spans are good for starters and learning. Many fly extremely well and thermal well. The larger 60" wing spans fly better and thermal better but you are more likely to have a tip strike if you mess up your throw, due to the 5 foot wing span.

Originally Posted by Lip84 View Post
3. I have a DX7 and am wondering which receiver to use. I am looking at either an AR6200 or AR7000. Both of them are full range and the differences are that the AR6200 is 6 channels, weighs 4 grams less and costs $20 (appx) less than the AR7000. All of these are bonuses but I want to check with old wise men prior to purchasing an AR 6200.
Depends on the plane. The DLGs require tiny receivers. AR6100 ro 6000s would be in order. The end pin receiver would be best for most DLGs. For the larger planes the AR 6000 seems to have enough range for 2M planes but the 2 part 6200 would be a good choice too, or the AR7000 for a full house plane. Depends on the plane.

Originally Posted by Lip84 View Post
4. What size battery should be used and what type? I have several 3S lipos but I know that they are too heavy for a glider. I was looking at getting anywhere from a 350mAh to 800mAh 2S lipo because I only have lipo charging equipment and they are lighter than nimhs and nicds. I have seen lipos as light as 20grams.
Some glider pilots use a 2S lipo with a regulator to get the voltage right. I belive the Spektrum receivers can take 8v but the servos generally can not so you need a regulator to step it down.

NiCd and NiMh packs are more common as the battery weight is helpful for balancing the plane. Your DX7 charger can charge these.

An Easy glider can fly all day on an 800 mah pack. Typicaly the DLGs have 250 to 350 NiMh packs, due to size and weight so you have to monitor them. I assume a lipo could work just fine. Matter of space and configuration.

Originally Posted by Lip84 View Post
4a. Is there an easy way to figure out the RX and servo draw on the batt to determine batt mAh size? I want to get a sailplane with R/A/E and possible flaps or spoilers at some time in the future and be able to fly for upwards of an hour at a time.
Anything over 1000 mah NiMh or 5 C lipo will handle a 6 channel sailplane. The demands are not that great unless you have a servo lock up on you. Just get into the habit of monitoring the level of the pack. I fly my 3M Thermal dancer on a 2100 mah pack. I have a voltage monitor on it that gives me the voltage reading every time I turn the plane on. I have never had to charge it during and 8 hour flying day.

I use an 700 mah pack in my Spirit. Never had to charge it during the flying day. Also has a voltage monitor.

I have 1100s in my slope gliders and those stay in the air for hours. I have never run them down either.

Originally Posted by Lip84 View Post
I think this covers the bases for now. Any recommendations on good intermediate sailplanes, either arfs or kits, would be helpful as well. I was originally looking at getting a Gentle Lady or Sophisticated Lady but later changed my mind towards the Kestrel at NESP. It is supposedly good for intermediate to advanced sailing and I like the look of it a lot.

Thanks!

Andrew (lip84)
You have not provided any budget guidance so it is hard to say. Nor do I know anything about your flying or building experience. Your radio will handle most sailplanes though it lacks sailplane specific mixes. However the user mixes can provide much of what is missing.

The Kestral looks like a fine choice. Use a little flap to elevator mixing for the spoilers and you will have an easy to fly, easy to land plane. The light wing loading should make for a nice floater.

The NEsail standard hi-start will launch it very nicely.

Good luck. Let me know how I can help.
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Old 08-27-2007, 06:51 PM
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That is very helpful!

Now, to answer some of your questions...

Yes, pure sailing is where its at for me. No cheating .

I am a fairly experienced flier. I just recently graduated from a MUS to a Simple400 pylon. As per my building experience, I have built one Guillows spitfire (the 17" wingspan ones), I rebuilt the nose section on my MUS after a bad loop and I built my Simple.

I was looking for a kit that I could build up and I was hoping to keep costs down, less than $100 would be nice but the DLG's seem to be expensive. I was looking at the DL-50 from MM and it looks good and not too expensive. I have read that it is supposed to be a good first DLG.

Can you speak a little more on regulators for batts? Where you can get one and what exactly they do? I am confused as to why they would be necessary. Is it simply that the battery pack puts out too high a voltage for a receiver to handle, that an ESC would normally regulate? It seems that my 1250mAh 3s lipo wouldnt be a horrible choice, its just a little on the big side. I would prefer to get a 2s lipo as they are pretty cheap and I have the equipment.

I was thinking of going with the AR6200 because its a little heavier than the 6100 or 6000, will help offset the lightness of the lipo, and for some reason I have more confidence in the 2piece receivers from spektrum (this may be an ungrounded reason but thats just how I feel until someone convinces me otherwise).

Thanks!!!

Lip84
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Old 08-27-2007, 09:10 PM
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Originally Posted by Lip84 View Post
I was looking for a kit that I could build up and I was hoping to keep costs down, less than $100 would be nice but the DLG's seem to be expensive. I was looking at the DL-50 from MM and it looks good and not too expensive. I have read that it is supposed to be a good first DLG.

Lip84
I fly both a Mountain Models DL50 and a Gambler + from Wright brothers. Both are good beginner DLG's IMO. The DL50 launches a little higher for me and will need to keep moving a little faster due to it's wing design. The Gambler+ doesn't quite launch as high but will float like a feather. Either one will serve you well to start with.
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Old 08-27-2007, 09:26 PM
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If you are looking at building a kit because you like to build, or because you like that plane, by all means build. For many people it is the best part of the hobby. However if you are building for economy, in this class of plane that no longer applies. You can now buy ARFs cheaper than you can build some kits.

The DL50 from MM is a good choice for a first DLG.

The Gambler also has a very strong following
http://www.wrightbrothersrc.com/gallery/gamblerag.htm

The Gambler has built up wings as opposed to MM foam wings. It takes a bit more work because you have to build up the wings and cover them, but the plane is much lighter, coming in at about 6.5 oz as opposed to 9 oz for the DL50. Either will be a lot of fun, but lighter is usually better.

A voltage regulator, such as the BEC in an ESC, steps the voltage from a battery to the 5-6V that the receiver and servos require. An example would be the UBEC. Plug a lipo directly into your receiver and you are likely to let the magic smoke out and nothing will work.
http://www.hobby-lobby.com/ubec.htm

You can use a 3 cell Lipo or a 2 cell lipo plust the BEC/Regulator. In essence, any voltage above 6 V will be turned into heat and wasted. If you go this way, go with the 2 cell lipo. Again, you have a NiMh charger suitable for NiMh packs that are usually used if you want to go that way as well. Either will work. A 4 cell pack will be about $15. However a 1500 mah pack normally comes with the DX7 packages so you may already have what you need.

For a 2M sailplane the 6200 would be a better choice if you can fit it in the plane. The kit you have named should have plenty of room. However for a 2M, I think the 6000 will serve unless you plan to take it to the limit of visual range. Then you might be pushing it, but I think it will be OK.
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Old 08-27-2007, 11:16 PM
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Lip84
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Just to make sure that I have this right...

If I want to use a lipo without my BEC (ie in a non-powered sailplane) then I just slap on a BEC and it will regulate teh voltage coming from the batter into the Rx and thus not fry the Rx.

I do have a 4cell Rx batt that came with my DX7, I believe that it is a 1500 mAh nimh or nicd (cant remember which). I noticed that it weighs a ton more than my 1500mAh 3s lipo though so I was concerned about using it in a sailplane. However, it was the first thing that popped into my head as I would not need to buy a new battery. I understand that this battery will keep a sailplane up in the air for hours after hours but its freakin heavy. I will have to weigh it and see I guess.
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Old 08-27-2007, 11:23 PM
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Weight is only a problem IFFF you don't need it to balance the plane. I have a 4 cell 6 ounce pack in the nose of my contest glider. If I took it out and put in a 2 ounce lipo, I would have to add 4 ounces of lead. Better to have battery than lead.

Build the plane, or buy the ARF and work on the balance. Then you can decide what to use.

When I bought my Spirit 2M RES RTF, I had to add 4 ounces of lead to balance the plane. It flew OK. When I redid it, I moved the electronics forward and managed to take out 3 ounces of lead because I moved the battery, servos, receiver, etc forward, thus using the electronics to balance the plane. Now it flies even better.

buy or build, then figure out what weight you need to balance. Position your electroncis to your best balance advantage. Then figure out what weight battery you want to use and where it will fit. You may want the lipo and BEC or you may want that 1500 mah pack.

in the photo you see the electroncis for my Spirit AFTER I moved it all forward. Originally the servos were under the wing, the receiver was where the servos are and the battery was where the receiver is now. I also drilled a hole in the nose block and put 1 oz of lead in the nose block making it more effective at balancing the plane. Net result was a reduction of 3 ounces, which is a lot.
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Old 08-27-2007, 11:41 PM
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Thanks a bunch Ed. I guess at this point the only thing left to ask is...is there anything else I need to know about DLG's? Tips, advice, words to/from the wise?

Thought of another one: is the Quick Flick 2 from MM any good? I see that it is a full build kit with wood wings as opposed to the foam ones of the DL-50.
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Old 08-27-2007, 11:52 PM
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www.radiocarbonart.com - several excellent videos on building DLG and how to launch them. Excellent.

Also, the video on Performance Tuning is for all kinds of gliders. Get it!

I have the QF2 kit on my building table now. Got it for next to nothing. It may be good and it may not. Mine is not done. The kit is OK. It promises to be lighter than the DL50 but if I was going to choose between the QF2 and the Gambler, I would go with the Gambler.

So - DL50 for easier build
And Gambler for ligher weight and possibly better flight performance

That would be my recommendation.
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Old 08-27-2007, 11:59 PM
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Ed,

I have a question regarding electric sail planes. I have a Cermark ARF that my Dad bought and crashed in the late 90's and I am trying to resurrect it. It has a 550 motor in it with a Him-3001 ESC. The ESC is a on/off type and I would like to have full variable throttle control. As it is now the motor will only run at full speed for a few seconds and then shuts off, but the servos still work as normal. Do you have a suggestion as to what ESC I could use to give variable throttle control? I would like to keep it all brushed for now as I am new to sail planes with and upgrade to brushless if I like it.
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Old 08-28-2007, 12:11 AM
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This would be a good choice
http://www2.towerhobbies.com/cgi-bin...?&I=LXMRH9&P=7

I don't know how much power that motor is pulling but it won't be more than 25 amps.

You need a brake in order to fold the prop - vital to a sailplane.

Chances are the battery pack you have is an old NICD that is probably no good and heavy as a rock. Go to NIMH or Lipo that will provide 25 amps.

Hope that helps. There are lots of others.
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Old 08-28-2007, 03:05 PM
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Ed,

Thanks for the info. The curent ESC is rated at 40 amps, but I don't know if the motor truly draws that much.
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Old 08-28-2007, 08:21 PM
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I took a look at the Rx batt that came with my DX7 and it is a 4.8V 1100 mAh 4cell nicad. it actually only weighs 10 grams more than my 3s 1250 mAh lipo (117g as opposed to 107g). With this pack being rated at 4.8V would I still need that external BEC/Regulator to adjust the voltage? it also seems like perhaps with the nicad only being 10grams lighter that the addition of a regulator for the lipo would cancel out that difference and just add one more point of failure in the electrical system (which is a bad thing).

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Old 08-29-2007, 07:16 AM
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No BEC. You just plug that NiCd pack into the receiver and it powers your receiver and servos.
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