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View Full Version : Glider vs Fighter Plane, most G's?


david burton
25th Jul 2006, 20:49
Hi everyone.

I've been thinking about the following question for a while, and can't find much evidence on Google so thought I'd ask here.

"I've heard a glider can pull more g's than a fighter plane, is this true?"

I was looking for the world records and was under the impression a glider's light weight enables it to pull more g's.

Any help gladly received! I have posted this elsewhere but was told to try this sub-forum.

Genghis the Engineer
26th Jul 2006, 07:48
Gliders are stressed to very high g values (a modern composite aerobatic category glider would be designed for routine operation up to 7g, and the actual structure for 2.25x that, so just under 16g.

But, I doubt that you'll find any glider with the control authority to reach those sort of values - glider aerobatics doesn't generally exceed around 4g, the extra margins are really to handle the operating environment - low wing loading / high aspect ratio, with manoeuvring and gust loads.

Conversely a modern fighter is probably designed to 9g, plus a 1.5 safety factor (maybe higher for a plastic ship like Eurofighter), so that would be around 13.5g - the difference is that it's got the control authority (and good reason) to go up to 9g and operate routinely.

G

Capt Pit Bull
26th Jul 2006, 08:31
Although more aged combat jets may well be substantially G limited to preserve fatigue life, particularly if carrying external fuel tanks / ordnance.

IIRC towards the end of its life the uk versions of the F4 were tooling around with something like a 3 G limit for some configurations.

pb

Genghis the Engineer
26th Jul 2006, 12:02
This reminds me of a conversation that I once had whilst working in the BDN P&HQ office for a certain frontline jet. We routinely got stupidly narrow clearances from the manufacturer (admittedly usually for ferry configurations) - say 0/2½g, which annoyed us, and annoyed the aircrew even more.


My boss came out of his office one day, and stormed up to my desk.

"Genghis, you fly microlights don't you?"

"Yes boss"

"What's the minimum flight envelope?"

"+4/-2g boss"

"Can you prove that?"

"Yep, I've got a copy of the airworthiness standard here on the shelf"

"Great, give it to me. I'm faxing a copy to (you'll have to guess the company) and telling them that for a NATO frontline fighter we are no longer accepting more restrictive g limits than a bloody microlight"

G

chevvron
27th Jul 2006, 11:42
During the war, the Germans built a glider-fighter with a prone pilot. Bet that could pull more G's than any other contemporary fighter!

Genghis the Engineer
27th Jul 2006, 12:14
During the war, the Germans built a glider-fighter with a prone pilot. Bet that could pull more G's than any other contemporary fighter!

The British experimented with something similar aftwards as well (a modified Meteor I think).

I gather that whilst you could pull lots of g, and get the fuselage section down (thus reducing drag) it was virtually impossible for the pilot to move their head effectively to maintain an effective scan.

G

GOLF_BRAVO_ZULU
27th Jul 2006, 14:53
Ah yes; the Meteor MK8 experimental prone positon pilot. Carefully preserved in the Air Force Museum collection. As it's at Cosford, though, read "carefully" with caution.

http://www.rafmuseum.org.uk/gloster-meteor-f8-prone-position.htm

chevvron
28th Jul 2006, 08:04
I read about the German fighter glider in the old 'RAF Flying Review' back in the early '60s (before it became 'Flying Review International) and seem to remember it was dived at incredible speeds; 400 - 500 kph I think.
It did have a narrow fuselage cross section, and was towed by a Bf110.