"Adelle" testing continued

[twistair]

Last week we continued testing "Adelle" after some modifications. First we installed oil radiator+oil thermostat on it. Second was that we removed hydraulic prerotator drive and moved the prerotator engine down - into the fuselage.
Photos below show the gyro before and after (without any prerotator here). This mod made some good things for the gyro:
- corrected gyro's CG location which resulted in more correct craft reactions in flight
- removed unnecessary weight from mast and rotorhead which resulted in better vibration picture and surprisingly
- decreased drag so significantly that I got 6-8 mph extra airspeed at same engine rpm

After the prerotator was removed I made two flights without prerotator at all. Funny stuff This was my first experience of taking gyro off without pre. SportRotor makes it's job excellently. Wind was only 10-12 mph but after rotating it to 30-35 rrpm by hand I managed to catch weak gusts and prerotate it. Very slowly, 3-4 minute to 85-90 rrpm, then very quick to 120 in first flight and 140 in second. Tractor config really helps very much in this - I noted it slightly adding main engine rpm while rrpm were 50-60 and rrpm grew more rapidly.

[twistair]

After these funny excercizes we installed new prerotator drive: pre engine was hidden into cockpit with crankshaft vertical and rigid shaft was installed instead of hydraulic drive. CV-joints - from small Russian car.
Testing showed that it gives solid 205-210 rrpm, no wind (hydro gave only 175-180), and works OK at rotorhead full travel in all directions.
I made another two flights with no surprises but got a surprise in the third one. That wasn't from prerotator but from main engine - at the end of the downwind leg engine rpm and thrust dropped suddenly, some unpleasant vibration appeared so I shut the engine off and landed half mile away from the airstrip.
The problem was in camshaft belt which jumped four teeth from it's marks. This is Subaru so exhaust valves stroke pistons on both larboard cylinders.
Later I was told this looks to be more or less regular problem for 2.5 Subs but too litlle information to the moment. So we have some smoke break in "Adelle" testing. Hope to continue them a week later.
Below are some photos of new prerotator with temporary prerotator engine cover.

[twistair]

I knew "Adelle" when she was as young and small
(white cabin is for her younger sister)

[ckurz7000]

Originally Posted by twistair

Last week we continued testing "Adelle" after some modifications.

That's one distinctively cool looking gyro! Bummer that the timing belt slipped damaging the valves and cylinders, though. Keep us posted,

-- Chris.

[GyroRon]

That gyro is the ugliest gyro ever made..... but it is so ugly it has a strange appeal and I like it. Hope to see video of it in the air one day

[twistair]

Originally Posted by GyroRon

Hope to see video of it in the air one day

Here it is Ron, see post #6 in this thread.

[C. Beaty]

Obviously not styled by Pininfarina, Michelotti, Zagato or even Magni.

It is reminiscent of a Piper Pawnee crop duster.

[twistair]

Likely of this thing, Chuck :

[C. Beaty]

For spreading insecticides or moving dirt, form follows function. For consumer appliances, function follows form.

[twistair]

Then to kill two birds with one stone "Adelle" designer should at least paint it's one side with something like this:




BTW: I added a bit more video of 'Adelle' to the Net. This is after removing old prerotator. Afterflight taxi is without prerotator at all, take-off - with new prerotator. Take-off roll is intentionally long since I'm still getting familiar with this craft. To make this task easier I shut off the prerotator engine (this may be heard at video) before starting the take-off roll (to exclude possible yaw) and kept it on mains much more longer than it needs. Also I didn't put all the throttle full, TO was at 4900-5000 engine rpm while full power is at 5300-5350. Just wanted to make it easier to control take-off pitch of the aircraft and maintain higher airpeed right from the ground.

[Alan_Cheatham]

What power output is your prerotator engine? Any specs on its make and model?

[twistair]

Originally Posted by Alan_Cheatham

What power output is your prerotator engine? Any specs on its make and model?

It's Raket 120, http://www.radne.se/store/, 14 hp @9000 rpm