Can we get total ground electrical power?

Ground electrical power should be available indistinguishable from that available in flight. That includes power to the sight unit and radar.

I own the Module, and have a basic know how of the startup, but it seems that there isn't much of a distinction between the ground power and the internal battery during a cold start. When I start the thing up, there doesn't seem to be a difference between the two. Whether I turn on Ground power or not, the thing manages to start up without much trouble.

The battery will go flat eventually and the voltage is less. But that's not the point. With correct ground power the sight, radar, and other systems can be used without the engine turning. Right now that is not possible.

You would expect that Ground power would be used exclusively for kick-starting the engine, and after the APU is up and running and keeping the aircraft powered, and then disconnect it as you ready yourself for take off.

I suppose that it would be a nice touch to test various high-energy aircraft systems before starting the engine.

There is no APU in the MiG-21bis. It's a starter-generator. I don't know how it got this weird name as an APU. Real manuals have a battery voltage and amp-hour requirement for internal start spec.

The real flight manuals make reference to checking all systems using external power. I just think if we have ground power as an option at all it should be the full service power.

I don't know how many flavors (Hz, waveform count, volts, etc.) of electricity can be applied through the ground connection in reality. Is this partial power even a thing? I could see the radar taking a few kW but the sight unit?

AFAIK the MiG-21 gets 28V ground power only. The Radar should be running on one of the PO-750A inverters, which I assume is only powered when the generator or ground power is connected, but not the battery. However these are more my assumptions, then the truth, as my Russian is still not good enough for fully understanding the manuals.

I had found a PDF Pilot's Manual in English for the 21-Bis that was translated into English in the ED forums. It goes over a lot of useful procedures and even some doctrine info, but the translation is a little confusing and over-descriptive at times. If you manage to find it, the book has a blue cover and has some Arabic Script in some places. It's very well worth looking over, and it appears that portions of it are used in the Official Manual from Leatherneck.

I do have that one, but it does not really describe the electrics.

MiG-21 have two electrical sockets for external power: one for DC (28V) and one for AC (115V). Any typical Soviet truck generator ( like older APA-50, APA-4 or newer APA-5, APA-80) is able provide full needed power for all systems.

I suppose the details of the electrical systems in the aircraft are for the mechanics, not the Pilots. Not to mention, the storied history of post-purchase modification of MiG-21's would mean that just about anything could be underneath those panels.

MiG-21 have two electrical sockets for external power: one for DC (28V) and one for AC (115V). Any typical Soviet truck generator ( like older APA-50, APA-4 or newer APA-5, APA-80) is able provide full needed power for all systems.

That is a nice picture. I was looking for that, but could not find any picture with more then one connection to the airplane. So do you need AC connected for the radar to work on the ground?

All variants have two sockets, only early aircraft have ( up to PFM ) one socket on the left fuselage side and second socket under fuselage right behind front undercarriage leg.

Yes, to radar maintance external power is needed. In Soviet service practice, always any typical activity with aircraft's systems is done with external power use. If you will check pictures, aircrafts are always connected to some APA, or fixed generator ( some big airbases had fixed electrical and fuel infrastructure ). In Soviet service doctrine battery is considered as auxiliary/emergency source of power, used only in non typical situations.

200 amp, 115 volt. 23kW. This is plenty for even the radar. Yes yes, peak compared to RMS and I'm sure that's a rating for the socket not how much you actually supply.

AC for some systems can come from No. 1 and No.2 converters of DC power. No. 1 provides essential AC systems like radio and engine ignitor. No. 2 provides some more less essential systems and in emergencies can act as No. 1.

But radar can't come through converters, only 750W each.

Maybe DCS ground power is only DC and not AC. I will check if there is any difference in systems available from ground power if AC Gen/Gnd switch on or off.

So that would mean on the ramp you would only use the 28V DC? Because that is what I am seeing on pictures of MiG-21 on the ground. I have yet to find a single picture with the second connector attached to the aircraft, but it surely would be done for maintenance.

So that would mean on the ramp you would only use the 28V DC? Because that is what I am seeing on pictures of MiG-21 on the ground. I have yet to find a single picture with the second connector attached to the aircraft, but it surely would be done for maintenance.

I suppose that for normal start-up, you would use only the DC socket. For maintenance, radar checks, etc. - both sockets would be used.

So that would mean on the ramp you would only use the 28V DC? Because that is what I am seeing on pictures of MiG-21 on the ground. I have yet to find a single picture with the second connector attached to the aircraft, but it surely would be done for maintenance.

Well, this depends from situation, one or two sockets can be in use. If service crew doing engine maintance and engine check runs, then only DC connector is in use, the same for engine start before flight. If some deeper maintance procedures have place, including avionics checks, then AC connector is in use as well. Generally from pilot's point of view most of time this is only DC socket, because he just need start engine, all routine preflight tests he doing with working engine so AC external source is no needed. Different story are maintance and overhauls works, technicians can't work with working engine so they have to use external power.

Hello Friends,

there are two switches for external power, one for AC and one for DC, both are working and AC power is even audible.

Battery switch switches DC external, AC gen switch connects AC external...

Switches marked Aerodromnoje Pitanje = and normally ~ or TOK.

It is now possible to power the radar with ground power. But still the ASP sight requires the engine started.