On Friday 25 July 2003 13:48, Christopher S Horler wrote: > Here's a few questions (btw the topic is the best word I could think > of). > > Stopping distances - I wondered if we were modelling these correctly on > any aircraft - specifically on the larger ones such as the b52 and 747. > > Fuel Burn - I think someone mentioned this once (and probably it was > modelled) > > Does the t/o weight for the b52 include a full payload or not. Further, > is there a way to 'drop' the bombs - a simulated change in cg and > reduction of mass (and trim condition) depending on what I drop/which > bays are emptied. Finally regarding the b52 I think someone once told > me that in order to takeoff with a full payload it was necessary to have > nearly no fuel on board so much so that you burn a bit of oil and then > immediately refuel once airborne.
> > Chris > The b52 doesn't have a weapon load but it does have a full fuel load and from what I was able to figure out from the various bits of diverse info I found, it's actually heavier than the normal take-off weight with a full weapon load. I think it's actually at the max take-off weight for the F model, which, as I said, is less than the full weapon load take-off weight. Also, many of the values had to be deduced from the various numbers I found for different conditions e.g. max take-off weights, max weapon loads, max fuel capacity etc. so while they're going to be in the right ball-park, they're probably not going to be really accurate. I'm pretty sure that the info you had about not taking off with a full fuel and weapon load is correct although I don't know how much fuel is carried for take-offs. I doubt the tanks are nealy empty but a top up after take-off is standard practice for many mil jets that carry a heavy weapon load. Another issue with the YASim b52 is that there's no water injection so it's even more underpowered at take-off than it should be. I think that it's about the right weight for a fully fuelled 'F' model but at the eqivilent take-off power of a 'B/C' model (with WI). I've been looking into using re-heat to simulate water injection but I've not got anything I'm happy with yet. In some ways it's been quite a difficult fdm to work on - I found that the take-off distances to clear a 50ft obstacle are around 10,000ft, which means a slow sluggish take-off, but then the rate of climb should be about 6000fpm. Then there's a max speed limit at low level of around 350 kts, which has to be combined with a high alt perfomance of 554kt @ 21,000ft and 495kt @ 46,500ft and I haven't managed that yet - I've not been able to sustain flight much above 36,000ft I've really concentrated on trying to get the take-off and landing characteristics right - the long low climb out and the flat shallow approaches. It should be remembered too, that unless you do a few hours of flying in it, or reduce the fuel load to start with, you'll probably be landing overweight - even though it can't get as high as it should, you'll be able to fly a very long way in it before running out of fuel. If you come across any hard info on these a/c I'd be pleased to try to roll it in, or you could have a go yourself - I'm not exactly an expert in this field and would be delighted if someone else can improve it. LeeE _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
