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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.

Gyro with camera

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.

BackMax1 Start

Video of BackMax1opt
(1.1 MB)

since 01.12.2001

BackMax1 was optimized: the outside ballast from the optimization experiments was transferred to inside the skirt (see Backglider Construction 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.

BackMax2 Start


Video of BackMax2
(730 KB)

since 6.12.2001

Unchanged rocket, as used in the optimization experiments. Nice gliding phase.
Tup=4,2 sec, Ttot=11,2 sec

Left photo: BackMax2 a few cm before leaving the launch tube.

BackMax4 Start2


Video of BackMax3
(910 KB)

since 7.1.2004

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.

BackMax4 Start1


Video of BackMax4
(634 KB)

since 7.1.2004

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 video).
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.

RuMMa2 1/25 sec after start

Video of RuMMa2
full bore (685 KB)

since 6.12.2001


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!

RuMMa with T-nozzle after start  

Video of T-nozzled
(770 KB)

since 7.1.2004

RuMMa with T-nozzle, ascending

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.

RuMMa2 with crumpeled nose Surprisingly, RuMMa2 survived at least 15 accordion style landings until today and still takes 8 bar pressure without complaints.
Cousin Diethelm 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 so far.

Hey, if you have downloaded ALL of these videos, you can be sure to be a WR addict  ;-)

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Stand / Last Revision:  07.01.2004

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