Tim Conrad's T-33 - Nose heavy?

[JJH]

I've recently noticed the aircraft's nose is pitching down during takeoff. The rear comes up first, and the nose only after liftoff. This seems to be a recent phenom as I don't remember this happening before. The only changes I've made to the aircraft.cfg have been small adjustments to wheel contact points and the addition of an autopilot panel. I cant locate anything resembling a centre of balance number. Any advice?

Jim B :-?

[JJH]

I've found what I think are the Centre of Gravity numbers:

reference_datum_position =  0, 0, 0
empty_weight_CG_position  = 0, 0, 0
CG_forward_limit = 0
CG_aft_limit = -1

I don't know what they represent, but I'll compare them to another period jet (F86) to see whether there are peculiarities and tweak them to see what happens.

[Travis]

Ummm . . . as far as I know, all taildraggers SHOULD pitch nose-down before they are able to get into the air.

The tailplane must begin to produce lift (just like the wings) before you can get off the ground.  I'm guessing that if you knew the EXACT moment that the tailplane began producing lift, you could get it to lift off without the tail coming up at all.

[Hagar]

Ummm . . . as far as I know, all taildraggers SHOULD pitch nose-down before they are able to get into the air.

The T-33 is not a taildragger.

JJH. It might be best to post this in the Aircraft Design section. That's where the serious tweakers hang out. You could also read the appropriate FS9 SDK.

[JJH]

Ummm . . . as far as I know, all taildraggers SHOULD pitch nose-down before they are able to get into the air.

The T-33 is not a taildragger.

JJH. It might be best to post this in the Aircraft Design section. That's where the serious tweakers hang out. You could also read the appropriate FS9 SDK.

I'll follow both of those suggestions, Hagar. In the meantime, I've changed the "elevator_effectiveness =" from 1 to 3 and that has corrected most of the problem.

Jim B

[Travis]

I'm sorry!  Went off a bit half-cocked, there.  Looked up "Conrad T-33" on FlightSim and saw shots of a Zlin!  Must be more tired than I thought . . .

[Groundbound1]

Hi Jim. Try this before editing any .cfg files. Start your sim and load a flight with the T-33. Once loaded, hit alt+enter to get the sim into "windowed" mode. (Skip it if you already fly that way). Now go to the aircraft menu from the menu bar and select fuel and payload. See how the plane is balanced out and if it isn't, from there you can make any changes needed.

[olderndirt]

Ummm . . . as far as I know, all taildraggers SHOULD pitch nose-down before they are able to get into the air.

You've got to be kidding

[JJH]

[quote]Hi Jim. Try this before editing any .cfg files. Start your sim and load a flight with the T-33. Once loaded, hit alt+enter to get the sim into "windowed" mode. (Skip it if you already fly that way). Now go to the aircraft menu from the menu bar and select fuel and payload. See how the plane is balanced out and if it isn't, from there you can make any changes needed.

[JJH]

Found what I think I need in the SDK. Just a matter of tweaking the Reference Datum and the CG offset numbers until I get it right. Tks all.

Jim B

[olderndirt]

Which seat is the 600 lb student occupying?

[flaminghotsauce]

[quote]Ummm . . . as far as I know, all taildraggers SHOULD pitch nose-down before they are able to get into the air.

The tailplane must begin to produce lift (just like the wings) before you can get off the ground.

[olderndirt]

The old adage that the tail must fly before the wings'll fly is absolutely correct but as the tail flies the nose merely goes from three point attitude to somewhat less but surely not 'pitching down'.

[Travis]

Sorry.  What I meant was what Older'n wrote: the plane "levels out" a bit as speed builds, then you are able to actually get the main gear off the runway.  No, I definitely understand that the nose shouldn't pitch "down" past the horizontal, but the tailgear must leave the ground before the main gear, correct?

[olderndirt]

Probably with full flaps and lots of horses it'd get off three point but you'd need to accelerate before trying to climb and get rid of the flaps nice and easy.