Starfighter ZELL launch

[Hobbes]

I knew there were plans for this, but I never realized it was actually tried:

[PR19_Kit]

Why launch it with the wheels down? The pilot only had to retract them later and the aircraft wasn't resting on them anyway.

[Weaver]

Why launch it with the wheels down? The pilot only had to retract them later and the aircraft wasn't resting on them anyway.

It looked like the wheels were attached to part of the hold-down system.

Did you see on the front view how it was going sideways? There was nearly no control until it got upto flying speed, which was a problem with all the ZELL aircraft, and made cross-wind launches problematic. That's one of the three justifications for my seemingly crazy ZELL Harrier proposal:

1. Much greater take-off weight, unlike a regular Harrier in VTO.

2. Control at low flyng speed immediately after launch via the Harrier's RCS system.

3. Ability to land vertically back at the dispersed launch site, or a different launch site, without needing a runway like all the CTOL ZELL aircraft.

[zenrat]

Smokin'!


It appears obvious to me that in order to mitigate the lack of control until flying speed is reached the wings need to be longer...

[Old Wombat]

Why launch it with the wheels down? The pilot only had to retract them later and the aircraft wasn't resting on them anyway.

Landing gear in a lot of aircraft have lock & unlock systems to activate & de-activate high speed & low speed controls, high speed for whell the wheels are retracted & low speed for when the landing gear is lowered.

Given that the ZELL launcher doesn't get the F-104 up to high speed having the gear down would activate the low speed control systems for the launch, then, once the JATO unit had done its job & been jettisoned, & the engine had pushed the Starfighter up to a more reasonable speed, the pilot would retract the undercarriage, thereby de-activating the low speed control systems & activating the high speed control systems.

From memory those systems control things like flap & throttle settings, with some more advanced systems also altering control surface responses to the stick & pedals.

[PR19_Kit]

That ZELL Starfighter had the gear coming up almost as soon as the rocket had fired.

[PR19_Kit]

It appears obvious to me that in order to mitigate the lack of control until flying speed is reached the wings need to be longer...

Self evident I'd have thought. 

[NARSES2]

Why launch it with the wheels down? The pilot only had to retract them later and the aircraft wasn't resting on them anyway.

Just in case it "fell off" the end of the ramp ? 

[killnoizer]

That system was only ugly .

[sandiego89]

Why launch it with the wheels down? The pilot only had to retract them later and the aircraft wasn't resting on them anyway.

Landing gear in a lot of aircraft have lock & unlock systems to activate & de-activate high speed & low speed controls, high speed for whell the wheels are retracted & low speed for when the landing gear is lowered.

Given that the ZELL launcher doesn't get the F-104 up to high speed having the gear down would activate the low speed control systems for the launch, then, once the JATO unit had done its job & been jettisoned, & the engine had pushed the Starfighter up to a more reasonable speed, the pilot would retract the undercarriage, thereby de-activating the low speed control systems & activating the high speed control systems.

From memory those systems control things like flap & throttle settings, with some more advanced systems also altering control surface responses to the stick & pedals.

Wombat is correct.  Quite a few aircraft have control laws and sub-systems that only work with the landing gear down, and this was the precise reason why the Zell F-100 and F-104 were launched gear down.  Things like slats, flaps, bleed air for blown flaps etc. may only work with the gear down.  Some limit control surface deflection past certain speeds, or have corresponding stick throw degradations, where a full stick throw at slow speed gives a large deflection, but such a deflection at high speed would be catastrophic.