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Learning to use a hi-start

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Old 09-30-2003, 04:24 AM
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aeajr
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Default Learning to use a hi-start

I am making this post because I could not find tips or advice anywhere on how a person, working alone, could learn to use a hi-start. I invite more experienced sailplane pilots to add their tips, comments and advice to mine.

These links may be helpful for background.

http://www.mrcss.org/pdf/articles/a_beginners_guide.pdf

http://www.labyrinth.net.au/~learmont/HiStart

Hi-start launching.

First, let's be clear, I am NOT talking about competition launches here I am talking about safe sport launches. I am sure someone will post about maximum altitude and such. I just want to help you get in the air safely.

Second, get a coach/instructor if one is available and ignore all of this. This is ONLY intended for someone who is unable to get help.

Third, your plane must already be well trimmed and flying straight and even from a hand launch. Fail to this and the hi-start will turn your plane to junk!

Fourth and very important, make sure your tow hook is in the forward most hole that your plane has. It should be a little in front of the CG of your plane. This will give you a more controlled launch than the more rear, competition positions.

OK? We understand the goal here? Safe and gradual build up. Control, not height!


Always launch into the wind. Launching is easier with a mild breeze than it is in dead calm air. For learning purposes I would say you want at least 2-3 MPH and no more than 6-7 MPH of head wind.

I was taught to launch with all controls at neutral. In fact my initial launches were with a little down elevator to help reduce the chance of a pop-off. But I started with a full size hi-start and an instructor who made the first 4-5 launches for me so I could watch and he could see how the plane would behave. Then he released the plane on the next three while I held the radio to control the plane. Then I released while he flew the plane. Then I did both. But we were working with the BIG hi-start in a huge field and he was there to guide me. If your plane is properly trimmed, all controls should be at neutral for your launches.

You should only need rudder to control the launch. You may use a little up elevator at the very very end to help release the ring from the tow hook, but mostly I just let it fly off. If you get your angle off a little left or right the plane will tend to go that way, just like a bad hand throw. Use the rudder to get it back to center.

Build up to it slowly. Think of a hi-start as an assisted hand throw. Do exactly what you would do on a hand throw. Basically flat firm throw.

I don't know what hi-start you have or how big it is, but if it is a "full size" hi-start it probably has 30 meters/100 feet of elastic and 100-120 meters/300-400 feet of line. That is an awful big thing to handle on initial launches without a coach.

You can either get an up-start which is 5-15 meters/15-50' feet of elastic plus 15-50 meters/50-150 feet of line which can be used in a smaller space and, in my opinion be a little less scary. Or, take your big hi-start, replace the big length of line with a smalle length. You can cut a 50-100 foot length to use for your initial launches You can reattach it later with snap swivels or just tie a knot.

Get a metal ring, 1.5-3 inches, that will allow you to loop the elastic onto the ring in some fashion to secure it so that you are only using part of the elastic you have to make the shorter launcher. Make sure the stake that you put into the ground has a washer on it that will not pull through the ring. Don't cut the elastic.

If you start small, say 10' of elastic and 30' of line it will be a lot easier to control, and the launch will be lower and the energy smaller. Again, just an assisted hand throw. We will use this length combination for this discussion.

Pull back 5-10 feet, or about 1/2 the length of the elastic, for the first launch.

Check to make sure all of your controls are working.

Stand firm and just give it a straight. firm, flat throw, controls at neutral. You should only need rudder to control direction.

It should go out just like a hand launch, only with a little more speed and it should naturally climb a little. It should just fly off the end of the line. Don't go for height, go for control.

Build up the strength of the pull over several launches. 1/2 the length of the elastic. Then 3/4, then the full length. Then 1.5 times the length of the elastic. Build till you are comfortable. Then just slide the metal ring further down the elastic and add more line. Use roughly 1 foot of elastic to 3-5 feet of line.

As the pull gets stronger, the plane will fly out faster and the lift of the wings will take it higher naturally. No need to throw it up, it will go up on its own. You can reserve aggressive angles and the more rear tow hook positions for competition.

I have about 60 launches with my Spirit 2 meter. I launch flat with neutral controls and the forward tow hook position. Using my smaller launcher (25' tubing and 100' line) I get 100-150 foot launches depending on the wind. With the larger one (100' elastic and 400' line) I estimate I go up 400-550 feet and can zoom off of the end if I want.

These links may provide some additional, useful info. Like you I was afraid of the hi-start. If you had someone to coach you through the first few you would be fine. If you don't, try this method.

That plane was made to fly. Fly it! [8D]


http://www.mrcss.org/pdf/articles/a_beginners_guide.pdf

http://www.labyrinth.net.au/~learmont/HiStart
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Old 09-30-2003, 12:40 PM
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Default RE: Learning to use a hi-start

The only item I have a problem with is the angle of release and the toss required as the power builds up.

High tension launches will tend to rotate the model if you release it at level or only slightly nose up attitudes. The model accelerates very fast and then tends to over rotate and force a possible pop off. For high tension launches I've always found that you're better off to have the model leave at a 45 to 60 degree nose up angle. I've seem many a pop off from this sort of over rotation under high tension.

BUT....

When launching at that sort of angle the model MUST have a very strong push so that it's truly flying before it leaves your hand. Too soft a launch will leave the model with little airspeed and a very high virtual wing loading from the line tension. This will often lead to a sudden stall and instant crash. So I think it's important that the modeler learn to use a sytle very similar to an Olympic javelin launch right from day one as the tension comes up to full. The fact that many of the much lighter and poly-hedral can sort of get away with sloppy launches is more due to good luck than to good planning. But add in a bit of cross wind or a slightly more sloppy style and you've got instant matchsticks in a bag.

Certainly it's very good training for later models that will be far less tolerant of sloppy launching practices.

Otherwise it's a very nice primer for beginners. The method of sneaking up towards the full pull is a fine one but I'd like to see more emphasis on proper technique as the power/tension comes up to the higher levels.
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Old 09-30-2003, 06:23 PM
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Default RE: Learning to use a hi-start

Thanks for your input and insight. You have provided the clarification and emphasis needed.
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Old 10-02-2003, 12:17 AM
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Default RE: Learning to use a hi-start

one trick i've started to use is employing the help of a scale. (i use a fish scale from wal-mart) while not the most accurate thing it does let me see the affects of a change of tension in a controlled manner. and it beats the heck out of counting paces.
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Old 10-02-2003, 10:13 PM
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Default RE: Learning to use a hi-start

kamakasi,

What are you flying?

How much tension have you measured on your fish scale?

What pull do you find gives you the best result?
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Old 10-03-2003, 12:00 AM
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Default RE: Learning to use a hi-start

aeajr,

right now i,m flying a great planes 2m spirit. i am using a dynaflite heavy duty hi-start. i find that 8 lbs. pull is a slight breeze works good. anything more and the plane starts to left hook [:'(]. i find that i need to decrease the tension as the wind increases. normally 1/4 increments is what works best. be advised that these scales are by no means consistent from one to the other, but the individual results are consistent. that being said, i arrived at my launch tension by first pacing of what i knew was a good (safe) length and noting the the lbs.. from there i started to keep a log while slowly adding more tension.
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Old 10-03-2003, 05:41 PM
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Default RE: Learning to use a hi-start

kamakasi

Thanks!

I have wanted to take a scale to the field but don't have one. I work by feel.
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Old 10-07-2003, 05:21 AM
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Default RE: Learning to use a hi-start

In an attempt to learn to use a winch, my original spirit was destroyed in a bad winch launch this weekend so I am going to build a new one from a kit.

If you have any building advice, I have posted a request for advice here:
http://www.rcuniverse.com/forum/Spir...1185655/tm.htm
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Old 06-16-2007, 04:40 PM
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Default RE: Learning to use a hi-start

Hi-start launching is the way most people get their gliders into the air, so I am going to bring this thead back to the top.

I want to add some new reference links to supplement my suggestions in the first post.

The angle method for placing the tow hook
http://www.rcgroups.com/forums/showp...8&postcount=15

Here is another informational post for those who like more
technical detail
The Physics of Hi-Starts
http://www.charlesriverrc.org/articl...artphysics.htm

Sailplanes are Wonderful!
http://www.*********.com/forums/showthread.php?t=5356

If you are new glider pilot, this is a great resource:
http://forums.flyesl.com/topic.asp?TOPIC_ID=224




Please add your comments to help new glider pilots.

New pilots, please feel free to ask questions.
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Old 06-25-2007, 05:37 PM
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Default RE: Learning to use a hi-start

Two cents worth from a "hefty" user....

I have been launching a Sailaire (149"; 9.5 lbs.) and a Windsong (and a Lovesong) (132"; 5 lbs.) for many years using a 50/150 combo. The rubber is the largest size that Hobby Lobby sells and the string is #18 carpenters twine (orange for good visibility). Both of these planes have rounded fuselages behind the wing so it is easy to wrap the full hand around it and give it a heave. I haven't measured the tension but it is probably in the 15 to 20 lb range. The typical launch angle is about 35-40 degrees (I could probably increase that but I'm just not as strong as I used to be) and I provide as much arm as I can to get that initial flying speed. I can expect about 1 in 10 launches to have some sort of excitement due to a wind shift or a heavy thumb. I used to use a 100/300 setup but found that the extra launch height wasn't worth the extra trouble associated with that much length. You need twice the space and if the wind isn't in your face, the parachute can easily end up in the next area code. I also found it much more challenging to hunt for a thermal at the 150-200 foot level.
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Old 06-25-2007, 07:28 PM
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Default RE: Learning to use a hi-start

Well I learned what I know on my own. Allmost that is! I started out handlaunching a wing. ( 1st plane) That was hard.
Next was a Spirit. Started with a lot of gentle tosses at the soccer fld. Next was a Cut down rather anemic hi start. This is /was after a lot of reading info from you very gererous folks. Thanks!

So here is my technique. Here in Hawaii a typical day will carry about 10/15 kts of wind and you can almost kite a two meter up to max elev. In fact lots of time the plane will takeoff by just a gentle push into the wind. So under these conditions I launch with a light throw at an angle of 10/20 degrees, and as Bruce says the climb angle quickly steepens and some forward stick applied. Occasionally popping off on the way up.
On those windless days, I stretch it out untill I can feel the last of the stretch and give it a healthy toss at about 30/40 deg. to insure it dosen't stall leaving my hand. I don't use a scale.

I don't have a real field to fly out of so my planes take a lot of abuse. ( Housing subdivision in progress as an example.)
For me I think setting up the trim, control check, and paying attention to wind direction, are key elements to a succesfull flight.

My next plane ( Spirit Elite ) is ready and waiting for the 25/30 kt winds to back off. Also ordered an Easy Glider to try some slope areas here on Kauai.
I also fly full scale Blanik, Swchiezer, Grob.

Aloha, Les ( Beginner)
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Old 07-02-2007, 03:26 PM
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Default RE: Learning to use a hi-start

Both the EZ Glider and the Elite will fly off a decent slope in 6Kts of breeze. I have flown both in 20Kts. I have found that, off a hi-start, the EZ stays up longer even tho' the flaps on the Elite should help - check the wing loading!
Daveosoar.
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Old 09-04-2007, 12:53 PM
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Default RE: Learning to use a hi-start

I have a winch available most of the time, so I don't use my hi-start that much any more. However this past weekend I took it out to launch my 60 ounce Thermal Dancer.

The one I use has 100' of either 7/16 or 1/2 inch rubber and 400 foot of line with anohter 100 I can add if the conditions are right.

I saw that I had lost some touch in how to use the Hi-start. My first few launches were not that high but as the launches built up I was getting higher and higher launches. Maybe the elastic had become stiff from sitting in my garage but it seemed to loosen up.

They won't match the zoom I can do with this plane off a winch but I was able to get enough to get a 25 minute flight and speck the plane out.

Hi-starts. Simple, easy, effective and very economical! :-)
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Old 12-19-2007, 11:12 PM
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Default RE: Learning to use a hi-start

Since hi-starts are so important to most glider pilots, I am going to bring this one back so it can help new glider pilots.
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Old 12-25-2007, 09:45 PM
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Default RE: Learning to use a hi-start

Also posted here ( http://www.rcgroups.com/forums/showt...=6#post8697661 )

For what it is worth!

I started flying again this past summer after a twenty plus year absence... Way back then I had to teach myself for there were no clubs in my area (and before the internet - love the internet now) that flew sailplanes... After I had built my 1st plane (gentle lady) I 1st bought 100' of bungee cord and 400' of line... Can only stretch the cord only so much, I slowly increast the pull (to a full pull) and at one time during launch the plane was 1/4 way up and seeing the wing fold and helpless watching as it came crashing back to earth (if i crashed it once, i must have crashed it a hundred times) I figured there must be a better way... I heard about hi-starts and being a cheapskate (hense the bungee) I had bought 100' of 3/8" surgical tubing (extruded - amber) from a local medical supply house and the difference was night/day... It was true surgical tubing and no UV protection... Well needless to say it did not last long before it became brittle and was breaking all the time... Never did catch a thermal... That was then and this is now... I picked up flying again and had bought this time the heavy-duty hi-start from Dynaflight and it worked pretty well but once again after heavy use it deteriorated rather quicky and this to was breaking all the time and the pull was noticeably weaker than when it first came out of the box in no time at all... Now I have purchased several "HoseMonster" hi-starts...

( http://www.aerofoam.com/hosemonster.html )

I had puchased a Pinnacle hi-start off of ebay for a really good price but have not had the chance to try it out yet but looks very promising...! It is quite different than the hosemonster and seems to be a different type of rubber than the mandrel-dipped and has a very thin wall, if anyone could shed some light here would be very appriciated... I know next to nothing on this one and their site does not say much about it... What and or how is it made/made-of, how can you tell which size Pinnacle hi-start it is such as diameter vs the mini, small, standard, medium, large or extra-large...? Still seems hands-down much better than the Dynaflight systems and much cheaper in cost than the hosemonster's...

( http://www.nesail.com/categories.php?subcatID=54 )


The HoseMonster rubber I have in the 2, 3 and 4 meter class... They are mandrel dipped and heavier wall thickness than the Dynaflight Heavy-Duty and seems to have a much smoother pull to them... I have them "ringed" at their 50' marks and can adjust the length with qiuck release hooks depending on the size field that I am flying at... I am using 500' of 200lb massion line also "ringed" at the 250' mark for adjusting to the size field... This seems to be a good way of doing this and I can also add sections together if more pull is needed by using (joining) the rubber in parallel (tandem) such as a 50' length of 2 meter rubber along-side with a 50' 3 meter rubber... I did spend close to $400.00 (i've spent at least as much on all the cheap ones added together) on all that rubber but have found it to be well worth the cost... No more cheap rubber for this guy, I have learned my lesson...! I also use the aerospace protectant "303"

( http://www.303products.com/tech/ind...FTOKEN=38121153 )

to keep them in top-notch condition and adds to the UV protection... I also have them stored in insuated Kelty Binto Cooler to keep them out of UV light and away from ozone which will also deteriorate the rubber... Store in a cool place...

( http://www.campmor.com/webapp/wcs/s...00226&langId=-1 )

I thought that I would mention since I have not really heard anyone talk about the care and maintenance of the very expensive rubber...! It makes a difference between making your hi-start last a long time or make it last a VERY LONG TIME...

Well, for what it's worth...
Kevin[sm=rolleyes.gif]

Hi-Start in Kelty Binto Cooler / Hi-Start with quick realese / Hi-Start in parallel (tandem) configuration
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Old 07-23-2008, 11:49 AM
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Default RE: Learning to use a hi-start

If anyone needs help with hi-starts, this is a good place to ask.
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Old 07-23-2008, 12:34 PM
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Default RE: Learning to use a hi-start

I have been a slope pilot during the 5 years I have been into RC. I have recently decided to try thermal soaring and participate in the acievement program of the LSF. I am building a Guppy sailplane and a DLG to start thermalling off some sand dunes at my beach house and need help with upstarts... I plan on making my own. I need some help on materials, size of bungee cord, size of cord, attatchment methods and releases.... I also want to know how to position the tow hook on my glider.
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Old 07-23-2008, 12:58 PM
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Default RE: Learning to use a hi-start

Visit Novice Lounge
> http://forums.flyesl.com/forum.asp?FORUM_ID=14

There are two articles on hi-starts there which add to what this one covers.

In the US, bungee and tubing are two different things. Surgical tubing is far superior to bungee.

The articles referenced at that link address more of your questions
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Old 12-10-2008, 09:23 PM
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Default RE: Learning to use a hi-start

I am putting together a home made hi-start using solid (not tubing) 1/4 inch diameter rubber. It's known locally as 6.4 mm barrier cord, and works very wellin fact I've just flown from a borrowed hi-start made from this. Trouble is, the supplier made up my order of 60 metres (enough for two hi-starts) as three bundles of 20 metres each. To make a 30 metre length,which is what I want, I will need to make a join.
How best to do this without knots or bulky joining rings ? Any advice gratefully received.
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Old 12-10-2008, 09:37 PM
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Default RE: Learning to use a hi-start

If it was a tube it would be easy. But solid.... tie a knot.
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Old 12-10-2008, 09:53 PM
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Default RE: Learning to use a hi-start

Thanks, Ed. Glad you were able answer straight away. I have found your posts exceptionally informative and helpful, especially for a beginner such as me. Incidentally, I located the illustrations of your "golf hat parachute" only after I thought I had scored a major el cheapo coup by buying one of those "on the head umbrella" sunhats, just the right size, eight panels, needing only a little modification after removing the frame, for a parachute. Cost: NZ$2 (about US$1) The golf hat, used, certainly goes one better. Many thanks for the help.
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Old 12-10-2008, 11:25 PM
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Default RE: Learning to use a hi-start

Glad I could be of assistance.

I used that hat because it was bright pink. It came from a company picnic.
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Old 12-11-2008, 12:58 AM
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Default RE: Learning to use a hi-start

Hi I too have used hi starts for quite a while, and one I also found was to have the hook on the glider more forward than usually recommended, on my last glider (recently totalled [:@] ) I had the hook slowly moved forward to about 1/2 way between CoG and the nose. it made for a more forgiving launch without the radical nose up without sacrificing much if any height gained. My glider was 174"ws R/E and I was using 1/4" surgical tubing doubled up to 100 foot with 400 feet 130lb dacron with a 40 inch 3 inch wide streamer, all of which worked quite well. I will in the very near future be building another glider, I miss my lil baby too much []
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Old 12-11-2008, 09:05 AM
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Default RE: Learning to use a hi-start

ORIGINAL: qldviking

Hi I too have used hi starts for quite a while, and one I also found was to have the hook on the glider more forward than usually recommended, on my last glider (recently totalled [:@] ) I had the hook slowly moved forward to about 1/2 way between CoG and the nose. it made for a more forgiving launch without the radical nose up without sacrificing much if any height gained. My glider was 174"ws R/E and I was using 1/4" surgical tubing doubled up to 100 foot with 400 feet 130lb dacron with a 40 inch 3 inch wide streamer, all of which worked quite well. I will in the very near future be building another glider, I miss my lil baby too much []
Sounds like your hi-start was not strong enough for your ship. But as long as it flew, and you liked it, that is all that matters. But I would not endorse this suggestion as a general rule.

1/4" hi-start rubber would be appropriate for a 2M 78" wing span ship in the 20-45 ounce range.

Doubled it might be good enough for a 3M ship where you want something between 12 and 18 pounds pull.

But yours was 4.4M. I would imagine that that plane was on the order of 6 pounds. For that I would want 24-30 pounds of pull on the hi-start. I have a 1/2" rubber hi-start that would probably be good enough for that one, but I have a heck of a time pulling it back that far by myself AND handling a 174" plane. For a really good launch of a 4.4M ship, that would be what I would expect to use in terms of a hi-start.

But, again, as long as you were happy, that is all that matters. Certainly moving the hook forward would help when you have an underpowered hi-start.
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Old 12-11-2008, 09:37 AM
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Default RE: Learning to use a hi-start

Hi Ed, you are probably right in that my system is too light to effectively launch my old glider, but it worked well enough to get my baby up high enough to find lift, even if it was slowly. It was also easy enough that I could launch on my own. The reason I lost it wasnt thru a bad launch, rather it was a radio/rx malfunction where I lost complete contatc with the glider about 60 seconds after launch. The glider had just been refitted with new pivot on the T-tail, new rudder hinges, new servo's, battery and rx. I was using a near new DX7 which I had had glitches with in the past, but it worked well enough on the first 2 flights that day, and after a full recharge on a 4500 mah pack I launched again, and after getting levelled out and starting to look for lift I totally lost any control and never regained it. At my club, nobody uses 2.4g any more for the same reason. I have gone back to using 36mhz (aust freq ) where at least most if not all nasty's are known. I have since sold my DX7. I hope to be getting some plans from another member here soon, and will build another big bird, I miss my baby lots [] I loved the long lazy flights where I could relax and enjoy it, flights of 30 minutes plus were the norm, with my longest being over 5 1/2 hours, and had a number of others having a fly too. thats why the big battery pack I have several electrics, but they just aint the same
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