jtrain609
Antisocial Monster
Beasley asked if it was possible to do a forward slip on a swept wing, transport category jet in another thread.
http://forums.jetcareers.com/lavatory/126286-holy-crap-swa.html
I believe that you can't, or if you technically can, it would result in your very likely untimely demise. Seagull feels differently:
I figured this discussion would be better served in this forum as opposed to the lav.
So here's why I think you can't do a forward slip in a swept wing, transport category jet:
1. You'd have to be at a low enough airspeed so as to be below Va for the tail, as you're going to be putting in a full control input and would prefer to not snap the tail off in the process. At these speeds, in my aircraft below 200 knots, I'm willing to bet that you could put yourself dangerously close to stalling one of the wings.
2. What would the affect be on the engines? How would a forward slip reduce airflow into the engines? On my aircraft, with the engines mounted on the tail, I'm willing to bet you'd either (hopefully) manage a compressor stall on the engine that is being blocked from air coming in by the fuselage, or (possibly) manage to flame the thing out because it doesn't have enough air flow into it. There's no buffet margin chart for forward slips in a transport category jet, so you have no idea how far you could take the maneuver before you can one of your engines.
3. The CFM doesn't allow for it.
4. There's no training on it.
5. What are the results of blocking airflow over the tail? In a traditional setup? In a t-tail setup? I honestly have no idea, and I only know it's an issue in some aircraft (Cessna 172's due to the high wing with flaps 40 in).
Now, you could trump all this by saying, "Well, you could do it if you had both engines flamed out and you were on fire and the president was riding in the back and the only possibility for survival is to do a split-S followed by a forward slip to a wheel landing in a 727, utilizing the tail as a tailwheel because your CG is out the back end because the elephants you were carrying stampeded to the back of the aircraft." In situations as crazy as that one, of course you're going to do whatever it takes to get the aircraft on the ground safely.
But barring that, I would say that from a practical standpoint, forward slips are not possible in swept wing, transport category jets for the above mentioned reasons.
I'd love to be proven wrong, but I'd also like to hear it from somebody that can say something besides, "Of course you can." Talked with engineers about it? Have data from flight testing? Let's hear it, I'd love to see an in depth discussion on this issue.
EDIT: I should also add, I'm picturing in my head a situation where you're 2,000' high at the marker, and you put a full control input in, in the form of a slip, in order to lose a ton of altitude and make the runway.
http://forums.jetcareers.com/lavatory/126286-holy-crap-swa.html
I believe that you can't, or if you technically can, it would result in your very likely untimely demise. Seagull feels differently:
I figured this discussion would be better served in this forum as opposed to the lav.
So here's why I think you can't do a forward slip in a swept wing, transport category jet:
1. You'd have to be at a low enough airspeed so as to be below Va for the tail, as you're going to be putting in a full control input and would prefer to not snap the tail off in the process. At these speeds, in my aircraft below 200 knots, I'm willing to bet that you could put yourself dangerously close to stalling one of the wings.
2. What would the affect be on the engines? How would a forward slip reduce airflow into the engines? On my aircraft, with the engines mounted on the tail, I'm willing to bet you'd either (hopefully) manage a compressor stall on the engine that is being blocked from air coming in by the fuselage, or (possibly) manage to flame the thing out because it doesn't have enough air flow into it. There's no buffet margin chart for forward slips in a transport category jet, so you have no idea how far you could take the maneuver before you can one of your engines.
3. The CFM doesn't allow for it.
4. There's no training on it.
5. What are the results of blocking airflow over the tail? In a traditional setup? In a t-tail setup? I honestly have no idea, and I only know it's an issue in some aircraft (Cessna 172's due to the high wing with flaps 40 in).
Now, you could trump all this by saying, "Well, you could do it if you had both engines flamed out and you were on fire and the president was riding in the back and the only possibility for survival is to do a split-S followed by a forward slip to a wheel landing in a 727, utilizing the tail as a tailwheel because your CG is out the back end because the elephants you were carrying stampeded to the back of the aircraft." In situations as crazy as that one, of course you're going to do whatever it takes to get the aircraft on the ground safely.
But barring that, I would say that from a practical standpoint, forward slips are not possible in swept wing, transport category jets for the above mentioned reasons.
I'd love to be proven wrong, but I'd also like to hear it from somebody that can say something besides, "Of course you can." Talked with engineers about it? Have data from flight testing? Let's hear it, I'd love to see an in depth discussion on this issue.
EDIT: I should also add, I'm picturing in my head a situation where you're 2,000' high at the marker, and you put a full control input in, in the form of a slip, in order to lose a ton of altitude and make the runway.
anic: 
