USMCFLYR

AND THE MIGHTY TA-4J TOO ADLER!

Even got to use it once upon a time in a life long, long ago!

FlyJSH

Thanks for the replies! I figured the 'Drivers' would give a more rounded and informative answer

I just couldn't imagine what advantages there would need to be to justify the safety and toxicity issues. Now I see.

Adlerdriver

I’ll bet that’s a good story.

Interesting tidbit in my googling. The Swedish fighters I mentioned apparently take off with the RAT deployed to be available in the event of issues immediately after airborne. I guess nothing wrong with being prepared.

galaxy flyer

Interesting, I would have thought the seat was the answer to any problem that might require the RAT. The SAABs are single engine. Engine failure on t/o? Seat. Loss of controls via hydraulic or electrics? Seat. I suppose simple generator failure might be solved by RAT. Then again, RAT out eliminates the hydrazine issues.


GF

tomgoodman

If you have some time in Tucson, this place is worth a visit:

Home | Titan Missile Museum : Titan Missile Museum

Makes one appreciate never getting that duty. The guides explain that the hydrazine fuel trucks and oxidizer trucks were not allowed to both be on the site at the same time!

FlyJSH

Much like the Germans with T-stoff and C-stoff. No little 10 inch diamond hazmat labels on those tankers. Just the letter 'T' or 'C' about a meter tall painted on every flat surface.

Excargodog

The problem with RATs on some fighter aircraft was related to the airspeed required to keep them going. With the A-7, among others,you needed about 200 knots to generate the hydraulics needed for directional control,and at 200 knots you landed on the nose wheel which woukd then collapse. If you tried to slow up more than that,you lost your hydraulics.

Back when the F-16 was being designed, a chemical backup system was wanted and the EPU seemed a perfectly reasonable thing to do. They had their choice between using hydrazine or hydrogen peroxide. Either one run through a catalyst would produce gas that would spin up a turbine. The hydrogen produced superheated steam and ammonia with traces of hydrazine,the hydrogen peroxide produced superheated steam and oxygen with traces of hydrogen peroxide. The hydrogen peroxide (80-90%, not the 3% you get at the drugstore), was more corrosive and tended to explode and create fires if it hit anything like grease. The hydrazine was safer....but then came the EPA and OSHA.

They wanted a standard for allowable exposure of hydrazines (note the plural). While straight hydrazine is relatively benign, some of the hydrazines used in missile (Titan) and rocket fuel, like mono methyl and unsymmetrical dimethyl hydrazine, are fairly toxic. But when they came out with a "hydrazine standard" that lumped them altogether, the law now required for any hydrazine discharge, even just plain hydrazine, to be handled by the same standards as the most toxic of the hydrazines.

I wouldn't go so far as to say the F-16 EPU issue is much ado about nothing, but it's definitely a case of regulatory overkill.

galaxy flyer

Now we’re doen this rabbit hole. The F-100 RAT was mounted inside the inlet and “extended” by opening a door on the dorsal. Being in the inlet, at high-ish power settings and low speed (low velocity flow) it stalled or even reversed. You couldn’t get much below 220 with power up and have hydraulics. Just a get to somewhere safe for an ejection.

The RATs on the Challenger and Global drop off the generator below about 140 to give the hydraulic controls priority. In the sim, flying an approach IMC and landing on the RAT is not too difficult.

GF

sailingfun

The A4 also had a RAT.