RE: Great Planes Spectra ARF

RE: Great Planes Spectra ARF
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RE: Great Planes Spectra ARF - 3/23/2007 2:04:34 PM

aeajr

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The Spectra is an electric version of the Spirit.

The Vista is a pure sailplane, more like the Spirit. The Vista EP would be similar ot the Spectra.

The designs are very close. It is possible that Tower bought the rights to the design from Great Planes, or that it is in fact the same plane under a different lable. The tower radios are all Futaba.

Common practice.

As for being a good first glider, yes, I think the Vistas or the Spirit or the Spectra are all good choices for first gliders.

< Message edited by aeajr -- 3/23/2007 2:05:21 PM >

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Post #: 26

RE: Great Planes Spectra ARF - 3/24/2007 8:07:05 AM

Semi Retired Aviator

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Thanks Ed. Your advice is appreciated.

And another thing if you don't mind helping out again. The stock motor/ESC recommendation is 7 cells (8.4 V). If I went to 8 cells, would the ESC still be OK (I'd be running a higher current) or would I need to go to a C35 mentioned earlier. The clear plastic srapped ESC provided with the ARF looks awfully similar to the Electrifly C-25 (itmay just be the same picture of course), and 8 cells at 3000mAH wouldn't get to 25 amps, or is my logic illogical?

Currently I look like going down your recommended path, stock motor and ESC, gearbox 2.5:1 and then 8 cells of NiMH, but I don't want to cook the ESC first time out.

SRA

< Message edited by Semi Retired Aviator -- 3/24/2007 12:35:48 PM >

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Post #: 27

RE: Great Planes Spectra ARF - 3/24/2007 1:22:02 PM

aeajr

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The ESC should be marked on how many cells it can take but I would be shocked if it could not take 8 cells.

8 3000 mah Sub C cells will give you many climbs but will weight about 18+ ounces.

Or you can go to an 8 cell GP2000AFHR or similar A size cells that can handle 25 amps+
This one is 2000 mah.
http://www.cheapbatterypacks.com/main.asp?sid=730974&pgid=loosecells&chem=NIMH

Not as much capacity, I would expect 5-7 good climbs, but the pack will be about 9 ounces or about 1/2 the weight of the SubC pack, and that is a HUGE difference in a sailplane. Short of going to Lipos, I would do this. Get two of these and you should have plenty of flying time. 5 climbs with some lift on each, let's say a minimum of 3 minutes would be 15 minuts of air time.

If you catch lift, you could be up for hours on one pack.

< Message edited by aeajr -- 3/24/2007 1:23:55 PM >

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Post #: 28

RE: Great Planes Spectra ARF - 3/30/2007 10:49:37 AM

Semi Retired Aviator

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I've been talking with guys who fly sailplanes, and they say that the Spectra is a good thermaller but not so good at slope soaring. Does anybody have views on this?

I guess, like powered aircraft, one type won't do everything equally well, so maybe what they say has some merit, but for my first sailplane, I am looking for something that I can use for a range of flying. So will the Spectra do it all?

Thanks again.

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RE: Great Planes Spectra ARF - 4/25/2007 4:41:17 PM

Rickochet

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I have a Spectra I built from the kit back in the early nineties. I flew it for years with the stock 550 can motor, 8 X 4.5 Graupner folder and 1500mAh Nicd sub c's. It flew well with a moderate climb and I often got 45 min. soaring flights. I recently got it out of storage after a 15 year RC break. I am going to upgrade the can motor to a Himax 3510 1100 brushless that is a direct bolt on replacement for 550/600 can motors and put an 11" or 12" folder on it. Also ugrading receiver to a Berg 4, T-bird 36 ESC and 4000mAh Lipo. May also add spoilers if I can find some info on how to do it. I still see the Tower still carries the kit after all of these years. Must say something about the design.

Rick

< Message edited by Rickochet -- 4/25/2007 4:42:17 PM >

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Post #: 30

RE: Great Planes Spectra ARF - 4/25/2007 10:33:02 PM

Semi Retired Aviator

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Thanks Rickochet. It does say something for the design.

I decided on a brushless motor and LiPo, and though I've received the box, motor, etc., I've yet to start construction.

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RE: Great Planes Spectra ARF - 4/26/2007 7:42:42 AM

Aquila223

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I have what used to ba a 2 meter Spirit with the stock Spectra motor driving a 3.5:1 gearbox turning a 15*12 folding prop on 3 cell lipos.

Climbs like a homesick angel with a 2.5 meter full house wing. On a 10 second run I can get 500 feet, Close the throttle and everything is trimmed so all I have to do is make the turns.

Stock is good but you can do so much better.

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Post #: 32

RE: Great Planes Spectra ARF - 5/13/2007 2:55:42 PM

TomTreese

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I keep reading on the Spectra threads about the problems with the weak tail section. On the ARF both tail fins bolt on??? These bolt on's never seem to be as strong as when they are epoxied together???

The new Tower EP Vista seems to be very similar to the Spectra but the tail is epoxied together So it should be stronger????

Would they be very similar in flight characteristics?????

I am considering one of these two Sailplanes and from what I read the Tower Vista may be stronger????
However the Multiplrx Easy Glider EP RR may be the answer????

< Message edited by TomTreese -- 5/15/2007 12:52:26 AM >

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RE: Great Planes Spectra ARF - 6/20/2007 7:27:11 AM

Semi Retired Aviator

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I noticed back on page 1 that somebody is using 8 cells (9.6 V) instead of the recommended 8.4 V with this motor.

Just how much voltage will this motor take? For example could I power it with 3S LiPo, nominally 11.1 V, but peaking at 12.6 V. I thought not, but can somebody more knowledgeable than me on electrics (most posting on this thread, I'd say) clarify this for me. I thought that brushed motors had a fixed voltage and if you put more into them they'd burn out, and only brushless used a range of voltages.

I had intended going outrunner, but am having weight problems, i.e., too light. The supplied brushed motor is quite heavy, and right out front. An outrunner is about a quarter of the weight, and the LiPo battery pack is also very light, so I'm going to have CofG problems if I don't add lead, something I'm loathe to do.

I'm thinking I may go back to the supplied motor, etc., but need to know if I can use the 3S LiPo battery. If it lacks performance, I can then add a gear box.

Last thing; is a battery pack made up of 8 X 2400 maH AA (NiMh) cells likely to be able to supply the current required? In theory they should, but I'm not sure.

Thanks for the advice; it's always appreciated.

< Message edited by Semi Retired Aviator -- 6/20/2007 9:34:25 AM >

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Giver her some more power.......She won't take any more!

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Post #: 34

RE: Great Planes Spectra ARF - 6/20/2007 1:08:29 PM

aeajr

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From: Long Island, NY, USA
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quote:

ORIGINAL: Semi Retired Aviator

I noticed back on page 1 that somebody is using 8 cells (9.6 V) instead of the recommended 8.4 V with this motor.

The stock Speed 550 or speed 600 can take 9.6V. 3 cell lipo might be a bit high for it. It will work but the life of the motor may be short

quote:

I had intended going outrunner, but am having weight problems, i.e., too light. The supplied brushed motor is quite heavy, and right out front. An outrunner is about a quarter of the weight, and the LiPo battery pack is also very light, so I'm going to have CofG problems if I don't add lead, something I'm loathe to do.

I'm thinking I may go back to the supplied motor, etc., but need to know if I can use the 3S LiPo battery. If it lacks performance, I can then add a gear box.

Adding a 2.5 or 3:1 gearbox and replacing the original 8X4 prop with an 11X8 will give you much better climb than stock using the original motor but you will not gain the efficency of the brushless motor, if it can turn an 11X8 or something in that range. The wider prop is much more efficent.

Brushed motor is likely to be around 50% efficient while the brushelss should be around 80% or better. So more power gets to the prop and less gets lost as heat.

quote:

Last thing; is a battery pack made up of 8 X 2400 maH AA (NiMh) cells likely to be able to supply the current required? In theory they should, but I'm not sure.

The answer is most likely no. AA cells are typically not able to deliver the 20-25 amps you are likely to need for the stock motor. I don't know what the rating is on the brushless so I can't say, but you will want a brushless motor that is rated at around 200 watts or higher in that plane.

A cells or even 4/5 A cells may be able to deliver the power you need. Depends on the MFGs rating. If the supplier says their battery can deliver 30 amps, then I would look to use it at no more than 25 amps so as to not over stress the pack.

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Post #: 35

RE: Great Planes Spectra ARF - 6/20/2007 1:10:30 PM

aeajr

Posts: 5496
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From: Long Island, NY, USA
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quote:

ORIGINAL: TomTreese

I keep reading on the Spectra threads about the problems with the weak tail section. On the ARF both tail fins bolt on??? These bolt on's never seem to be as strong as when they are epoxied together???

The new Tower EP Vista seems to be very similar to the Spectra but the tail is epoxied together So it should be stronger????

Would they be very similar in flight characteristics?????

I am considering one of these two Sailplanes and from what I read the Tower Vista may be stronger????
However the Multiplrx Easy Glider EP RR may be the answer????

If you want, you can epoxy on the tail of the. Nothing stopping you. Bolt on is for ease of assembly and transport. But if you want to glue yous on, you can.

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Clear Skies and Safe Flying!
Ed Anderson
Moderator
Park Pilot Program Partner

(in reply to TomTreese)

Post #: 36

RE: Great Planes Spectra ARF - 6/20/2007 4:44:45 PM

TomTreese

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From: Williamsburg, VA, USA
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Thank for your advise on another thread. I bought the Multiplex Easy Glider EP RR. A great choice.

I have 18 flights with a 21 minuted duration flight.

I am using a 9.6V 8 cell NiMH battery which give me 6-7 minutes of power to climb to 500 feet and still enough to line up with the runway.

I am very glad I bought the foamy A/C since I failed to keep the nose down on the second landing and it stalled and went in nose first, a bit hard. It took 5 minutes for a CA fix and it was just fine. A balsa plane would have had much more damage..

I painted the wing botoms with Top-flite spray. It went on well.

Thanks again.

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RE: Great Planes Spectra ARF - 6/21/2007 11:05:21 AM

Semi Retired Aviator

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Thanks Ed for the good information.

Finally, has anybody actually installed a gear box in the Spectra? As I look at it, it is going to need some cutting of the fuse to fit it in. The T600 motor doesn't have much space around it.

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Giver her some more power.......She won't take any more!

(in reply to TomTreese)