How long can a glider stay in the air?

[johnlernert]

Generally flight time of RC gliders on one time battery charge is around 20 minutes but what we are trying to do is to increase its flight time by the already gained momentum and not by increasing battery…
That is we will be switchhing off the battery during flight time for at some moments and let it fly on its own by the gained momentum…
Due to this mechanism we will able to increase the life of the battery and let it fly for more than the normal time

 

[Wayne]

John,

Not sure what you are getting at here. My gliders are limited to my bladder limits in terms of flight times. My Slow Stick has a battery life of around 20 minutes.

If we are talking about e-gliders, then it really depends on the glider and the conditions and the pilot skills.

 

[jvaliensi]

How about the LSF 8hr duration flight? Done many times before fancy Lipo batteries were around.

 

[HENNY]

Generally flight time of RC gliders on one time battery charge is around 20 minutes but what we are trying to do is to increase its flight time by the already gained momentum and not by increasing battery….

That is we will be switchhing off the battery during flight time for at some moments and let it fly on its own by the gained momentum….
Due to this mechanism we will able to increase the life of the battery and let it fly for more than the normal time

Are you discussing a powered glider ?. It's easy to shut down the powered motor. I don't think turning your flight pack off is advised.

 

[iflylilplanes]

Back in the day, I stayed up on the slope for 2 hours on the old 800 milliamp Ni-cad 4 cell pack. Could have gone longer, but it was getting dark.

Where did you get 20 minutes from?

 

[bracesport]

I am just happy to survive ten minutes on the slope and them I can sleep happily that day!

 

[HENNY]

yeah even 1 minute is good especially if you land in one piece.

 

[johnlernert]

How about the LSF 8hr duration flight? Done many times before fancy Lipo batteries were around.

What do you do on a 8 hour flight?

 

[Konrad]

What we do is fly!

I use a clocking circuit to power the servos at a much lower frequency. Most analog radio power the servos at about 50Hz. For long duration flying I've clocked power to the servo as low as 5 HZ. While this extends the battery life it does have a huge cost in servo speed and servo RMS (average) power.

All the best,
Konrad

 

[Doc J]

Nick Shaw broke the World Record for F3 Glider Duration, at Ivinghoe Beacon, England. Nick's model was launched at approximately 6.30 am on Friday 8th September 2001. It landed soon after 18.30 on Saturday, a few metres from the launch point. The flight duration of 36h 3mn 19s has been ratified as a new World Record. The old record of 33h 32mn 30s has stood for 18 years.

 

[Konrad]

Do we know what onboard power system these guys used? Heck, do we know what was their personal power system? At that point without sleep I start to get real incoherent.

I thought I might have a schematic of the clocking circuit I used/made, but I can’t find it. It came from the old R/C Modeler magazine around late 70’s early 80’s. I made about 10 of these (one of my first attempt at etching a PCB)

But basically with this clocking circuit we use this to turn off the servos for a much longer time period that the classic frame rate of the old analog radios. As I recall we did this by interrupting the signal wire. This effectively negated the servo's feedback circuit so that the servo's amp would not drive the servo's motor.

 

[Konrad]

Found one of my battery extender. I was hoping that I might have had a copy of the RCM article with it, but alas no. It is basically a clock with a switch.
The clock is an RC (resistor capacitor) circuit and a monostable multivibrator. Driving a counter that controls the switch.

This particular unit I have not added the resistor (the two holes under the cap (blue thing)) to define the switching frequency.

With a good eye you might be able to reverse engineer one.
(Wow, I see as a kid I didn’t do a good job removing the flux!)

CD4047 Monostable Multivibrator
MC14017B Decade counter
MC14066B Quad Analog Switch
Looks like a 47 pico farad cap

All the best,
Konrad

 

[HENNY]

Found one of my battery extender. I was hoping that I might have had a copy of the RCM article with it, but alas no. It is basically a clock with a switch.
The clock is an RC (resistor capacitor) circuit and a monostable multivibrator. Driving a counter that controls the switch.

This particular unit I have not added the resistor (the two holes under the cap (blue thing)) to define the switching frequency.

With a good eye you might be able to reverse engineer one.
(Wow, I see as a kid I didn’t do a good job removing the flux!)

CD4047 Monostable Multivibrator
MC14017B Decade counter
MC14066B Quad Analog Switch
Looks like a 47 pico farad cap

All the best,
Konrad
View attachment 3329
View attachment 3330

Gosh Konrad you are like a world famous RC museum.

 

[Konrad]

Is that code for Pack Rat?

All the best,
Konrad

 

[Hank GB Z]

Konrad,

I still think your attic is the best hobby shop in San Francisco.

Hank

 

[Wayne]

LOL - Probably is.

 

[Konrad]

Konrad,

I still think your attic is the best hobby shop in San Francisco.

Hank

In S.F. not the bay area, that would be Aloft Hobbies

 

[Glenn Beer]

Did not people use hi capacity non rechargeable cells for long duration glider flights?

 

[Konrad]

YES, we did! Well I did.

 

[purview]

Generally flight time of RC gliders on one time battery charge is around 20 minutes but what we are trying to do is to increase its flight time by the already gained momentum and not by increasing battery…
That is we will be switchhing off the battery during flight time for at some moments and let it fly on its own by the gained momentum…
Due to this mechanism we will able to increase the life of the battery and let it fly for more than the normal time

gained momentum and in general flight time (of let's say RC gliders) is limited by the mechanism of the power source. To increase flight time by switching of life of the battery can only work at some moments (...they must not, but can, only increase the glide on its own).
The funny moment is when is who cares? Although your team is able to increase the life of the battery for more than the normal time -> momentum gained
or how Konrad replies:

YES, we did! Well I did.

have a nice ..?