Readers suggest LOHAN mount single mighty rod
Vulture 2 launch method prompts lively debate
Following a successful test of LOHAN's fantastical flying truss (see vid, below), we concluded that we'd go with the truss suspended under a single balloon, and inclined to allow the Vulture 2 as vertical a launch as possible.
Regarding how the spaceplane might be attached to the truss, we teased that we'd had "a bit of a lightbulb moment as to how to mount the Vulture 2 underneath the structure, allowing it to launch freely without recourse to any form of release mechanism".
We then invited readers to speculate on just what our solution is. Chris W kicked off with:
You need two parallel rods, one going through each wing of the craft and something for it to shove off of. When it gets to the end of the rods it's on its own.
Well, our original launch concept showed parallel rods in a couple of the options...
... but our revised plan is to sling the Vulture 2 under the truss, rather than above it, and launch along the length of the structure. Code monkey kept the two-rod method on board, and suggested:
With LOHAN under the truss, some (longish) rails under each wing should hold her securely through the buffetting of the ascent, but provide little resistance when the rocket kicks in.
David Rollinson objected to this plan, noting:
You'd be surprised how these things can work fine on the ground, but not at altitude. The launch rails will be subject to icing and possibly thermal effects, so may not be exactly parallel at launch altitude.
David was in favour of a single rail. He continued:
To retain the rocket on a single rail I'd suggest a loop of fine fishing line through two small holes (pinholes really) in the exhaust tube; the line will have plenty of strength to hold the rocket in place but the engine will burn it away on ignition leaving the rocket free to launch.
We're getting closer. Reginald Gerard also objected to the twin-rod set-up:
Ever since I saw the initial design with two parallel rods I have been wondering if that isn't a high risk launch option. There are several factors that could result in those rods not staying parallel during the course of ascent.
The rods being mounted on different parts of the platform structure 'could' result in either a convergence or divergence of the rods due to thermal changes and loading stress in the platform structure as it ascends into the colder regions of our atmosphere. This would effectively 'clamp' the craft between the rails during launch and wreaking havoc on the whole platform when the engine is ignited.
Reginald agreed with David that we'd be better off simply hanging the Vulture 2 from a single rod.
Well, that's exactly what we intend to do, although you'll have to wait until tomorrow for a full explanation of our cunning plan, complete with a big graphic description for your viewing pleasure.
Naturally, our beloved reader experts will already be pondering a hundred ways a single-rod method could go titsup, so here's Chris W again, highlighting possible pitfalls:
The problem with one rod is that the craft might spin and the wing drag along the truss, potentially causing damage. Another possibility is that during the ascent the wing remains in contact with the truss and freezes to it. Or if you really want to consider other possibilities there is nothing to say that the rod won't warp towards the truss and have the craft launch into it.
Perfectly reasonable objections, but we reckon we've got it covered. Tune in again tomorrow for the "LOHAN sits astride mighty rod" revelation. ®
Further LOHAN resources:
- New to LOHAN? Try this mission summary for enlightenment.
- You can find full LOHAN coverage right here.
- All the LOHAN and Paper Aircraft Released Into Space (PARIS) vids live on YouTube.
- For our SPB photo archive, proceed directly to Flickr.
- We sometimes indulge in light tweeting, as you can see here.