Old Koreelah

Any cheap ($100) Chinese compressor will suck the air out of your vacuum bag. Just remove the intake filter and rig up a threaded nipple to allow you to fit a hose which connects to the bag.

Old Koreelah

Morning Icebob, sounds like your success should be my guide.

When I conservatively applied Tony Bingellis' air inlet formula (0.35 sq inches X hp) I got a figure of 124 sq cm for 55hp (which I'm sure my 1600 will never approach) My inlets are heaps bigger than that, and the exits total 280 sq cm. I was more worried that at cruise the engine would run too cool!

Instead it seems that overheating whilst ground running is a certainty.

Did your cooling ducts follow the formula?

Regards

Old Koreelah

Hello Icebob,

It's reassuring to hear I'm not alone in wasting lots of effort with cooling. I sure wish I'd seen the Great Plains and Aerovee systems before. Looks simple as. Just a big skirt running horizontally around engine to ensure air has to go down past fins to get out. Perhaps I'll tear off my complex ducts and build something like that, or just buy a set of laser-cut fences from Aerovee.

Regards,

Old Koreelah

Thanks for the reply, Icebob. I am using the oil recommended by my VW guru (can't remember brand, its locked away now) but I doubt it would make the sort of difference I'm seeing.

My old VW donk was just sticking out in the wind and lacked gauges; assessment of temp. was guesswork.

With the knowledge that the exhaust valves area has vertical fins and needs the air shoved down past it I spent weeks building a pressure cowl with carefully-designed ducts channel the air. It sure doesn't seem to be working.

What sort of cowling arrangement did your VP have when you gained the results quoted above?

I have found a hopefully reliable article on the net which recommends the best temperature range for VW CHT's in order to ensure long exhaust valve life. This authority recommended 412-428°F as acceptable on climb and 338-345°F on cruise.

My problem is that when testing my cooling modifications with ground running, all four cylinders rapidly climb to 420°F. I can't find a recommended temp for this mode, but it does seem high.

Any advice?

Regards,

Old Koreelah

Thanks for the advice, people. My D9 Jodel currently has Toe-in and is rather hard to handle, especially on tar. I will reverse the lower legs. Tony you may remember my struggles trying to tame your thruster on the ground. My feet are too far from my brain!

Regards,

Old Koreelah

To improve ground handling and reduce the chances of losing control of my taildragger, I need informed advice re whether to toe in main wheels or toe them out. All I can find is conflicting recommendations. Any ideas?

Old Koreelah

Bubble canopy & fence wire

a good reason NOT to partially open a canopy before a forced landing is if passing thru a wire fence at speed is a possibility. A properly-designed canopy should pass wire over the crew's heads. Acrylic bubbles have allowed decapitation in some cases. My preference is a 2mm lexan/polycarb screen to deflect birds, etc, a strong steel hoop/roll bar, and a perspex/acrylic bubble which can be smashed. The remaining question is whether the steel hoop will be deformed by a flip over,reducing the exit space.

I am in the process of balancing my wooden Hoffman prop. Static balancing it on blades shows the need for a mass weight on the side of the hub. There are six large plugs interspersed between the holt holes. Can anyone enlighten me as to their purpose, before I do something irreversible like drilling one out to see what's in there. I suspect they have a balancing function, and I'd rather adjust the mass there rather than inserting lumps of lead into the wood.

Nothing on the Hoffman site sheds any light on this. The prop's data placard reads as follows:

Gerate Nr. L-32.11/1

Baumuster: H011*-150 8 70L

Werk Nr.: 37829

Prufung: 38675-1

Datum: 11.10.77

Thanks in anticipation,

Lyle

Zenith Carby on VW

I am fitting a new 1600 VW to my Jodel D9, with the original Zenith carby and intake system from my old Stamo engine. It worked well on the old donk; very economical and no hassles. It's fairly low profile, so visibility shouldn't be impaired too much.

Lyle

Pix attached

I'll try to get a pic of the Zenith above VW this weekend.

My 1600 VW has a Zenith mounted over the engine. Intake passes from the carbie thru a 'T' section set into a low profile box thru which hot oil flows. Cools the oil, warms the intake and is no higher than the lowest ignition available.

I love side slipping, but have heard a stall can result if prop wash disturbs airflow over the down wing. Not nice near ground. Maintain airspeed and straighten up with plenty of height.

Old Koreelah

Sign of CO effects

Another sign of CO poisoning is the "wicks" of the fingernails are no longer pink.

Fibreglas International in Brookvale sell DERAKANE, a vinyl ester resin which I'm told is petrol and ethanol safe. I'm using it.

Jodel D9