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papafish
08-09-2005, 05:25 PM
I'm a new flyer and have thoroughly destroyed an Ascent and a Tipsey. I don't live anywhere near a flying club so Im out on my own (hence the destructos!).
My Father-in-law gave me a glider he built but never flew (he's a builder of all kinds of models but not a flyer) he can't remember what it is.

It is 100" ws, Kit, electric - Cobalt 15 motor, rudder,aileron,elev,flaps. It has a 12 cell 1700ah NiCd pack. I set the CG at 1/3 the wing chord (10 3/16" chord) at root and it is way tail heavy (balances at about 1" behind the 1/3 mark!). The kit has a very defined battery compartment - not easy to move the battery around.

2 questions: Any Idea about what it might be and where to find the specs? I would like to change the battery pack and if I changed to LiPos I could at least move the battery weight around a bit for the CG placement. Any suggestions on this?

Jason T
08-09-2005, 05:46 PM
papafish,

Welcome to Wattflyer!

Do you have a picture of this glider? What about where it was bought and how old it is?

papafish
08-09-2005, 08:02 PM
Thanks Jason. I thought Ihad attatched the picture but I guess I teched out...I'll try again. It would have been probably been bought in Appleton Wisc., perhaps 8-10 years ago.

smoking joe
08-09-2005, 11:38 PM
Looks a lot like a 2M Spirit from the wing tips and canopy. Joe

Jason T
08-10-2005, 02:56 AM
papafish, unfortunately, I have not seen this one before.

Smoking joe, welcome to Wattflyer. :)

papamendy
08-14-2005, 01:14 PM
Papafish...I too am new to EP sailplanes ...but have flown off of high starts for years. I know it is pure evil to add weight to sailplanes...but I have had some pretty good luck with older models that were also 2 meter set-ups where I found the center of gravity too far aft. I have glued soft foam blocks forward under canopy...and the cut slits into the blocks and used lead pieces pushed into the foam block slits to where I got the plane balanced. I realized this added excess weight to the plane....BUT they glided true and and some of them turned out to be some of my best flyers...in a related story....I was given an Aspire EP 2 meter a week go...attempted to fly it as it was put together by someone who had built many planes. The plane seemed way under -powered and handled poorly. Came with 550 motor 8/4 prop...6 cell Nicd. I re-balanced the entire plane using the method described as COG was WAY off to the rear. I ordered all new engine/batt/prop to fly this plane and give it the power it neded to climb to glide hieght. Just for the hell of it I took it out with the stock set-up again to give it a try....still under powered BUT it actually climbed at about a 20 degree rate....and when I killed the engine it glided GREAT with no input from me. Totally nuetral....now I cant wait for the new parts to come so I can get stronger and more climbs from this plane...I know I added 2 more ounces of weight to the plane BUT now it actually flys as it was intended to. I gotta say I love this electric stuff now....so much easier than the high start...I still love the simple design of the old sailplanes.....with Elv/rud control....and just spending as long as I want playing in the rising warm air. Again just my 2 cents....and I know adding weight really kills some guys....but I would rather have a plane I can actually soar..... few oz. over...than a featherweight that is off balance and just sits in the attic.

papafish
08-14-2005, 10:34 PM
Thanks papamendy. The buddy who taught me to stay aloft suggested the same thing. He suggested I try a good test throw to check it out before I mess around which of course is the right thing especially considering the price of Lipo replacements. I agree with you about the weight though and will at least see how much it would require.

I have not actually got thoroughly soaring yet, lets just say extended flights, but I'm determined. I used to hang glide in the late seventies/early eighties but it is so inconveinient to get to the good sights. I'm hoping I will get some vicarious pleasure out of this and not have to try paragliding. I have some tricky but great flying sights here I just have to get good enought to use them. Thanks for the advice.

BillM
08-17-2005, 04:22 AM
papafish
The picture you posted does not give too much detail to work with but it may be a Great Planes Spirit 100 conversion given the wing tip shape. Keep in mind that is only a guess on my part. However having said that I can say that the only two conversions I've seen were very heavy and difficult to balance. I never got to see one fly and don't know if either one ever did fly.
I can't remember what the power system was in either plane other than to say they were not brushless systems as this was some years back.

I'm not saying the plane wont perform. I flew an overweight Sig Riser 100 for several years on a Speed 700 and ten 1000 MAH cells. Performance wasn't earth shattering but it flew. You may find yours will too.

BM

Old_Dog
09-01-2005, 03:54 AM
Balancing the CG: I have to tell you that this is what I've been told, not what I've accomplished. I believe it to be good advice.

"CD position will make or break a glider's performance. The best way I know of to establish the CG is with the well-know 'dive test' - the plame must first be trimmed to fly 'hands off.' With the plane at a safe height, fly across your view, apply down elevator to initaite a shallow dive (about 30 degrees), then release the stick and watch what happens. An immediate pullout means the plane is NOSE HEAVY and the CG should be moved back. If the pullout is very sow or even gets steeper the CG is TOO FAR BACK. Somewhere between those extremes is the sweet spot, which is entirely a matter of personal preference, depending on whether you want a plane that's sensitive to lift (aft CG) but with reduced pitch stability, or vice versa. Look up 'dive test' on the internet for further details."

Hope this helps. I intend to use it.

papafish
09-01-2005, 03:44 PM
I did fly it to check the CG and as predicted it was way aft. I acquired a LiPo battery 4S 3100Ah, less than half the weight and half the size and nearly twice the duration. Even with this in the most forward position it needed a little lead to bring the nose down at the 1/3 root chord position. Went to charge the battery after fixing all the set-up and it was a dud...so return it and wait again. I will use all the CG positioning advice I have received and read...which for the most part is consistant and try again. I will report on the results. I don't think the plane is a conversion as the frames seemed to be factory cut & numbered and provided a perfect battery compartment.

ptb
09-12-2005, 11:20 PM
The 1/3 back from the leading edge, applyies to a straight leading edge wing!
With tapered back tips, your c/g would be further back! The dive test is good
once the airplane is up,to fine tune the trim. the safest way is to find some tall
grass, and gently toss it towards the horizon, it will either stall, dive, or
gentley glide towards the soft grass! This has worked for 50 years for me.
should work for you also!

papafish
09-13-2005, 06:07 PM
Thanks ptp, It turns out that I shorted the battery. For an old dog who's been in maintenance and all the associated wrangles of keeping things going (or in pristine contdition if I was lucky) for a lifetime I was a little embarrassed to say the least. It changed my work habits, so that's a bonus!
I assumed from my previous tests that the CG was going to be further back, nice to know why. Whats worked for you will work for me... I'll do it as you suggest, thanks again.

stan mccarver
09-20-2005, 04:50 AM
papafish looking at the pic you sent I think you may have an old astro challenger on your hands.
Stan

BillM
09-21-2005, 03:57 AM
Stan
The shape of the wing is similar. However the Challenger had a 78 inch wingspan. Papafish stated his had a 100 inch span. It may have a modified wing and if so you may well be correct. The shape of the fin is also suspect. It appears to have a straight leading edge. The Challenger was more curved. The shape of the nose as well as the length is suspect as well. Again this could be the result of modification and the Challenger would need such a modification if it were to house a Cobalt 15G.

BM

stan mccarver
09-21-2005, 05:13 PM
Bill,
I stand corrected. you are right, just went out to my shop and looked at my old challengers ( I have the two meter with out electric and the mini wi astro o35 cobalt) . I thought way back when astro tried to market a 100 inch version like Mark Smith did with the wanderer. Just a guess.
Stan

BillM
09-22-2005, 04:10 AM
Stan
We live in a world of guesses. But it sure is fun in cases like this.

BM