Launch report: Backglider Videos 01.11.2001
The construction of backgliding (some say backsliding) rockets and my optimization process as well
as the theory behind this art is described on my
Backglider Construction page.
|Today, we took videos instead of photos. They are a bit large to download,
but as the discussions in the WR list showed, the movement of backgliding
rockets are difficult to describe with words alone.
Video of BackMax1opt
|BackMax1 was optimized: the outside ballast from the optimization experiments
was transferred to inside the skirt (see
page). We did not take any altitude measurements this time.
Tup=4,4 sec, Ttot=15,9 sec
Left photo: BackMax1 a few cm after leaving the launch tube.
Video of BackMax2
|Unchanged rocket, as used in the optimization experiments. Nice gliding
Tup=4,2 sec, Ttot=11,2 sec
Left photo: BackMax2 a few cm before leaving the launch tube.
Video of BackMax3
|After 2 comes 3! What was easier than to screw a third bottle into the
successful modular construction? In the days before I had built some more
Robinson couplings and matching sleeves for the Fanta bottles.
BackMax3 flew well right from the start without any further trimming. However,
we went through the entire optimization sequence (starting from 2, 4, 6,
8 bars with air only). So we made sure not to destroy the new rocket in case
it had a tendency to nosedive.
Tup=4,5 sec, Ttot=13,8 sec
Left photo: BackMax3 a few metres after leaving the launch tube.
Video of BackMax4
|What comes after 3??? Correct, a 4th bottle was incorporated in the next
step, yielding a rocket length of 95 cm. This one needed some additional
nose weight to achieve a stable ascent. We added a short guppied nosecone
as a hood and taped a 5 gram screw under it.
With this, the backgliding went exemplary well for moderate pressures (see
Tup=3,23 sec, Ttot=8,6 sec
However, when we launched it with the maximum intended pressure of 8 bar
and 300 ml of water, the rocket went very soon after leaving the launch tube
(at max speed!) into the backgliding position (tilt angle change from 0°
to ca. 90°). In spite of the tremendous crossway forces, the rocket
survived this several times without harm.
This model stays "under construction" until further notice.
Video of RuMMa2
full bore (685 KB)
To have some contrast, we fired RuMMa2, the perfect
nosediver (no backglide/backslide).
Left photo: 1/25 sec after start with 8 bar.
Whoosh! The air smells of smoke!
Video of T-nozzled
To have some contrast of the other kind, here is a video of the same rocket, this time with a self-machined
T-nozzle at it's end. Just before the video recording I lost a brandnew WR in a nearby field. That's why the video
is less impressive as it could be: I fired the T-nozzled rocket (RUMMA2, 2 liter with PET fins) with only 200ml water
and 5 bar - I did not want to loose this one also.
||Surprisingly, RuMMa2 survived at least 15 accordion style landings until
today and still takes 8 bar pressure without complaints.
||My cousin Diethelm Weltin was so impressed by my recent backgliding
experiments that he came all the way from Dresden to Freiburg to see the
rockets fly and help me launch. We had a great morning, maybe 30 launches,
perfect weather. Unfortunately, we ran out of time to bring BackMax4 to
perfection. In total, one of the most successful and happy launch sessions
Hey, if you have downloaded ALL of these videos, you can be sure to be a
WR addict ;-)
to the Backglider (Backslider) Construction page