Power for Graupner Cirrus

[Merco 61]

Hello,

I,m not well versed with electric power.I have a nice old Graupner Cirrus and have been thinking of mounting a geared motor in the nose.I have a Kontronic Fun480-33 with gearbox and Jazz 40-6-18 esc..Would probably look for a 14x10 folder and 3 cell 2200 lipo.Am I likely to achieve safe self launching using this combination please ?

[Esteban Tornielli 1]

Posted by Merco 61 on 28/10/2020 16:00:04:

Hello,

That's a good setup for the Graupner Cirrus. With a non-geared outrunner you may save up to 3 oz, using a smaller prop with less thrust, but still enough to bring that bird into the sky.

ARF model 75 (T tail) is slightly heavier than the one with built-up wings. Don't expect to win a thermal contest : -) , you're adding a whole pound to a not-precisely-light sailplane, but that ship is cute. I'll do something similar as I've got a 75 new old stock.

Cheers

.

[Shaun Walsh]

Seems a shame to cut the nose off a vintage glider. I believe the Cirrus used the same over wing power pod as the Cumulus originally which has the advantage of requiring no mods to the fuselage. Take a look at my "Cumulus Resurrection" thread.

[Tom Gaskin 1]

You're right Shaun, I had a Cirrus in the '70s with the Graupner overwing power pod. I stuck an old Frog 150 in it for some relaxing self-launching flight.

While a motor in the nose would be more efficient, I think it would be a shame to cut the nose off.

Tom

[Shaun Walsh]

Posted by Tom Gaskin 1 on 29/11/2020 10:31:55:

You're right Shaun, I had a Cirrus in the '70s with the Graupner overwing power pod. I stuck an old Frog 150 in it for some relaxing self-launching flight.

While a motor in the nose would be more efficient, I think it would be a shame to cut the nose off.

Tom

The power pod was designed originally for an OS10 glow engine and comes with aluminium pod sides, ply engine mount and plastic top and bottom mouldings.

I substituted a Hobbyking SK3 2836-1500 driving an 8 inch folding pusher prop running on a 30 amp speed controller and 2200 3S battery.

[Gary Binnie]

There are two quite different Graupner Cirrus models.

The oldest kit is a very lightweight rudder/elevator model with a built up wing and Airfix style plastic fuselage. It has a mid-mounted tailplane. In the full size world this is known as the 'Open Cirrus' because its 18 metre wing span places it in the Open class.

The second Graupner Cirrus is described by them as the 'Cirrus 75', in full size terms it is known as the Standard Cirrus (15 metre span, no flaps). The model has a fibreglass fuselage and a T tail. It's quite similar to their Mini-Nimbus which is a 15 metre class glider (15 mtr span, camber changing flaps allowed). I've had one on the board for a while.