Long-term Memory

Place: Halle
Tanks flown: 2
Time flown: 1h01 (cumulative model timer: 24h20) (including a lot of setup-time for the governor)
Rx battery recharged with: 268+1472 mAh (same behavior as some weeks ago)
Tx battery recharged with: 554 mAh
Glow heater battery recharged with: 439 mAh
Starter battery recharged with: 141 mAh

Comment:
I just bought myself a governor and needed to test it out. Besides that, a fairly calm day at the field. Besides testing out the governor, I continued to exercise my figure-8’s and nose-in hoover. After the last flight, I noticed that the rotor wasn’t rotating as freely as it used to.

When investigating this at home, the tail rotor made a slight rubbing sound:

The locking pin to keep the tail rotor shaft in place came out of its place. Pushing it back and re-tightening the set screw solved this problem.

Also, I basically undid the tracking adjustment: “black” was too high, so I decreased its pitch by 1 turn.

The governor

A governor is a device that stabilizes the rotor speed using a feedback mechanism. The Futaba GV-1 uses a Hall sensor to detect the magnets attached to the engine-fan. Here is the report about the device itself, its installation and the first test results.

From the 2 flights I did with the governor, I’m fairly happy with it. It does what I want it to do: govern the throttle to keep constant RPM. I must admit that I don’t (yet) do very demanding maneuvers…

Continue reading ‘Flight log 2008-08-15 – Governor’ »

Place: Halle
Tanks flown: 2
Time flown: 0h34 (cumulative model timer: 23h19)
Rx battery recharged with: 824 mAh
Tx battery recharged with: 576 mAh (did 0h51 of sim as well; sim cumulative timer: 15h25+0h36)
Glow heater battery recharged with: 304 mAh
Starter battery recharged with: 55 mAh

Comment:
A windy but nice day at the field, although the sun was low and annoying.

Practiced small figure-8’s (20m total width) and hoovering in different orientations. I’m able to keep the heli steady for quite some time in nose in (i.e. around 1 minute).

Place: Halle
Tanks flown: 1
Time flown: 0h17 (cumulative model timer: 22h45)
Rx battery recharged with:
Tx battery recharged with:
Glow heater battery recharged with:
Starter battery recharged with:

Comment:
Another very windy day at the field. Practiced some stall-turns in windy conditions and nose-in hoovering.

Place: Halle
Tanks flown: 0.5 + 1.5
Time flown: 0h59 (cumulative model timer: 22h28)
Rx battery recharged with: 787 mAh
Tx battery recharged with: 475 mAh
Glow heater battery recharged with: 275 mAh
Starter battery recharged with: 55 mAh

Comment:
Mainly a short flight to check the new balance tape and correct the tracking: the “black” blade needed 1 turn more pitch (which roughly gave it +1° compared to the other blade). After that some basic flying around with stall turns. Did some adjustments on the throttle-curve to keep the rpm up when braking with some negative pitch.

Continue reading ‘Flight log 2008-07-26’ »

Place: Halle
Tanks flown: 3
Time flown: 0h51 (cumulative model timer: 21h29)
Rx battery recharged with: 173+1408 mAh
Tx battery recharged with: 672 mAh
Glow heater battery recharged with: 862 mAh
Starter battery recharged with: 62 mAh

Comment:
Another windy but beautiful day. Verified the tracking with the new balance tape: still good.

Had to replace the glow plug; it completely died after (or during) the first flight.

Tried some (successful) stall turns, mostly on my right side. I didn’t dare to do it as much at my left side due to some unpleasant memories.

At the end of flight 3, the RPM suddenly dropped and the rotor started “flapping” again: the (new) balance-tape wasn’t so good after all…

When recharging my Rx battery, my Graupner Ultramat 12 reported the battery “charged” after pumping in 173mAh. Giving it a second try did fill it up by a total of 1581mAh.

Recently I had to configure a router serving as an IPsec-GRE endpoint. So far, nothing special. The interesting part is that the terminating router is behind a NAT-device which changes the outer IP-header of the IPsec tunnel. Of course, the GRE-header is NOT affected by the NAT (since it is encrypted).

To summarize, the device needs to:

• terminate an IPsec tunnel between 172.16.2.2 <-> 10.0.0.4 (its own IP); but authenticate as 172.16.2.4
• terminate a GRE tunnel between 172.16.1.1 <-> 172.16.2.4 (a public IP that is NATed towards it)

The diagram is shown below:

172.16.x.x addresses are “public”; 10.x.x.x are private.

Continue reading ‘Terminating an IPsec-GRE tunnel behind NAT’ »

A few months ago, I got the FlyCamOne2 as an add-on for my Raptor. The manual mentions that the recording can be started and stopped electronically. With some additional electronics, it should be possible to start/stop the camera from the ground using one of the free channels on my remote.

The free channel can’t be used directly: the receiver sends out pulses of different lengths (between 1ms and 2ms), while the FlyCamOne2 needs a simple short to start recording. Some electronics will be needed to convert between these two.

After some googling, I found the CurveRC FCO2 I/F which does exactly that. But there are some downsides:

• It consumes a lot of power (10mA on 5V)
• Isn’t cheap (£10, plus international shipping, at the time of this post)
• I don’t get to enjoy myself figuring out how to do this myself

The CurveRC print seems to be build around an Atmel Tiny25 microcontroller, which is an 8bit RISC processor with 2K of build-in flash. Using a microprocessor makes the design fairly simple since nearly everything can be done in software. However, it must be clocked at reasonable speed to do something useful. This explains the fairly high power consumption.

So I decided I could do “better”.

Continue reading ‘Convert PPM signal to digital’ »

When studying for my Cisco ISCW exam, I wanted to get somewhat more in-depth information on the different DSL-techniques.

First of all, there are different DSL techniques, ranging from IDSL (providing 144/144kbps) over the popular ADSL (somewhere around 1/10Mbps up/down) up to the newer VDSL variants (around 50Mbps). Within each technique, there are different modulation schemes.

I decided to explore what my Alcatel SpeedTouch modem (now Thomson) had to tell me; here is the report.

Continue reading ‘ADSL technology in Belgium’ »

When experimenting with Cisco routers, it’s very nice to have a (small) lab environment to test things. Unfortunately, Cisco routers tend to be fairly expensive and noisy, especially if you need 5 or more of them. So I was looking for a cheaper and more flexible solution.

Dynamips is a Cisco router emulator which loads an official Cisco IOS-image and runs it on emulated hardware. It started out as an emulation of 7200 routers only, but now supports 3600 and 2600 series as well.

When you want more than a single router, you’ll need dynagen as well. Dynagen connects to a running dynamips instance and does some magic to get the (emulated) ethernet-ports connected to wherever you specify. The network-topology is created using plain text files. While this seems scary at first, the excellent tutorial covers every frequently used scenario.

Both tools are Open Source software and run on Linux and Windows (although it needs cygwin and doesn’t run as stable). The only catch is that you need real Cisco IOS images. The cisco.com site provides downloads only to selected users. Another way to get them is to copy them from a real router.

Continue reading ‘Emulating a router: dynamips’ »

As reported in my previous post, I needed to re-balance the rotor-blades. Again… Also, the glowplug needed a checkup.

The glowplug was easily fixed: some oil got between the alligator clip and the glow plug which caused some bad contact. After cleaning both the clip and the plug the glow heater was able to pump 4A through the circuit.

Rebalancing the blades was a bit more work…

Continue reading ‘Flight log 2008-06-09 – Follow up’ »