Stick and Rudder

 

Jodel
Questions and Answers

Jodel Project | 2003 | 2004 | 2005 | 2006 | 2007 | 2008 | Q&A

Dealing with gaps between control surfaces

Hi Bill,

Here are 2 photos of the Balsa wood strips I added to the stabilizer and the elevator in order to prevent the air from passing through the gap. When both parts are joint (hinge bolts inserted) there remains only a small slit of approx 1 mm. That should stop the airflow. To allow the bolts to be inserted I had to carve out a certain part of the triangular Balsa strip (see photo)

Juergen


Subaru EJ22 engine and isues of weight

Hi Bill,
I finally found an EJ22 engine with 119000 km total which I could get at 750 EUR including the electric generator and the freight expenses.When I talked to the danish representative for the autoflight reduction drives he warned me about the weight. According to him the total weight of the EJ22 with redrive and all the other component like watercooler, plumbing, fuel pumps etc. will exeed the total weight of the original O200 system. What is your answer to that? Is he right? You are the expert since you have a EJ22 system on board.
Regards Juergen Thiel

Hi Jurgen
I have had a look through my internet pages for the answer to your question on weight. You will find my observations on Progress 2004 October. My weight for the basic engine was 99Kg and my estimate for all up weight was less than 130Kg. The aircraft welder who fabricated the engine mount took the weight into account when setting the distance from the fire wall. He also turned the engine to the right as, at the time, I had intended to use a right turning prop which would make the "P" effect turn the aircraft to the left. As you know I have since installed the Autoflight PSRU and this turns the prop to the left so my aircraft tends to go to the right needing some constant left rudder. I will fix this by adjusting the mount in some way not yet decided.

Another question in my mind is "Should I have gone for a PSRU with 1.9:1 reduction as I have or would 2.2:1 work better?" At this stage I think the 1.9:1 is optimum as this gives good flexibility at not so huge revs (RPM). The engine develops its full power at well over 5,000 rpm. Currently with 1.9:1 PSRU ratio my engine only reaches 4,600 rpm at full throttle in level flight so about 115HP is my guess. This is plenty of power but is the reason I am getting a cruise IAS of about 90 knots. Not sure what my 90 knots IAS would be in True Airspeed but probably a little more.

I have no doubts about the fact that if you use the Subaru, stick with fuel injection. I have twin webers which are working well but I am inclined to swap back to injection for reasons such as altitude adjustment and simplicity and also the injection would fit inside the cowl. At this time the air filters poke out in a rather odd way.

You will know I use a Warp Drive three blade prop. 70 inch diameter and 12* pitch as set by the warp drive gauge. I have tried everything from 10* to 15* and find the engine is best suited to 12*. At 10* it overrevs and goes more slowly in cruise and at 15* it cannot get onto the power curve so if you reduce throttle power drops off very quickly.

The radiator on my Jodel is large 500cm x 500cm (Nissan 300ZX) at the moment I have this covered 80% with a sheet of aluminium. I am using a Subaru thermostat which opens at 78 degrees and both the thermostat and the 80% block out are necessary to get any heat into the engine. I have a pressure gauge in the cooling system and my engine now warms to 80 degrees and sits at 10 pounds pressure. The radiator cap is a 13 pound limit but I have not lost any coolant due to over pressurisation in the system. I will eventually change the radiator for a much smaller unit but at this stage I think the volume of fluid in the larger radiator (6litres) helps keep the system in balance. The radiator sits under the cockpit floor and works like a scoop. I will change the angle and have this large radiator at a nil angle to the wind so reducing drag.

At more than 4,400 rpm the engine exhaust is noisy. Even with the exhaust/muffler system now fitted I am told by people on the ground that my engine is loud but with headsets it is OK in the cabin in flight. The exhaust outlet is fairly well back and I think this helps keep the noise away from the cabin.

This email can form the basis for my higher degree in Subaru engine development? From the University of Parchim!

Bill Coote

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Stick and Rudder
PO Box 284 Laurieton NSW Australia 2443
Ph: 02 6559 9953 Fax: 02 6559 7797 E: bill@stickandrudder.com.au

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