-----Original Message-----
From: Michael Coates <xair@...>
To: X-Air_Ultralight_Aircraft@... <X-Air_Ultralight_Aircraft@...>
Date: Saturday, June 24, 2000 8:17 AM
Subject: Re: [X-Air_Ultralight_Aircraft] X-AIR CENTRAL Re: Questions about the Xair F

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Bill Magrini wrote:

?Hi Michael,?Thanks for helping.?The flaps were set by the former owner - Guy at Speedwing.? When in the up position, they are almost exactly even with the ailerons.? They are about 1/2 cm higher than the ailerons, which I set with the stick per your instructions. We align the flaps level with the underside of the wing - using planks of wood or similar to do the job.?I flew the plane by myself this afternoon.? It was a perfect day for flying.? The plane flies great with only me in it and 10 gal of fuel.? I was able to cruise from 50 to 65 mph (43? to 56 knots) It should be going faster, is the ASI accurate ??, can you check it with a GPS ?, depending on my power setting.? I could hold level flight down to about 5000 RPM (50 mph or 43 knots) 5000 rpm on the Rotax will do just over 50 on ours.? There was no adverse yaw.? It seems my problem was mainly with two heavy people in it.? Of course, I want to fly with two people at times.?I hope you are wrong about the Hirth having 5 HP less than book.? Since I get book RPM, I was assuming I was getting full HP, Is your tacho accurate ???? it may say your getting full rpm but it may be much less - therefore much less horsepower.... can you get a lend of a digital tacho for comparison. There is something major wrong and i dont know what ?? we just have to eliminate the obvious first but Matt from Recreational Power (distributor for Hirth) says the engine will pick up a few HP as it breaks in.? Perhaps that is some of the problem.?For your 582 engines:

• Do you load it up to full gross weight? We fly ours at 490kgs in Australia
• How does it perform with two heavy people? Very well - 582 900 feet/min at 450kgs
• What prop do you use? Make, size, pitch? Brolga three blade 68" diameter 17 degrees
• What gear reduction do you use? Rotax e box 3:1 ratio
• What is your cruise, stall, and climb speeds at full gross?? Cruise 55 to 65, stall 25ish depends on heat etc.. climb ? they like to climb out hands free at 50 knots but you can pull them back to 35 but i like to let them fly
• What is the 582's power settings at cruise and climb? We gear climb full power 6500 rpm cruise 5200 to 5400 for 55 to 60 knots - all day long

Thanks for your help.?Bill MagriniXair - Virginia/Maryland?-----Original Message-----
From: Michael Coates <xair@...>
To: Magrini, William J <william.magrini@...>; X-Air_Ultralight_Aircraft@... <X-Air_Ultralight_Aircraft@...>; Bertrand Cheval <randkar-ulm@...>
Date: Saturday, June 24, 2000 12:26 AM
Subject: [X-Air_Ultralight_Aircraft] X-AIR CENTRAL Re: Questions about the Xair F
?>I really don't know ??,? there are too many variables here for me to work out.
>We don't have any fitted with Hirth engines so i don't know about the engine,
>the speeds are in MPH and we work in knots (even though Australia is Metric) and
>i have never used or seen a powerfin propeller.? I am going to try and convert
>all your figures and see what i get.
>
>I am also going to post this on the eGroup bulletin board for other owners
>worldwide to have a look at as there may also be another owner out there with
>the Hirth. Finally i have forwarded this to the factory in France, as they have
>more exposure to different configurations.
>
>A big question before we chase ourselves in circles is, how did you set up the
>flaps and ailerons, i have found the wrong flap setting in the "F" will upset it
>considerably !!, it needs to be set up properly to fly at it's best. The other
>thing i have heard about the Hirth's (and don't quote me it is third hand) is
>that the HP figures quoted are not close to the true achievable performance....
>take 5 HP of it ?? i would like to know the answer to that one also
>
>Thanks Michael
>
>"Magrini, William J" wrote:
>
>> Michael,
>> I am running a Hirth 2706 on an Xair-F
>> I have a Powerfin F prop with a 3.16 reduction.? My 68" 3 blade prop is set
>> at 14.5 degrees pitch to give me 6000 RPM at climb and about 6200 max RPM.
>> The plane weighs 256 kilos with 7 gal of fuel and full gross or 450 kilos,
>> with one 210 lb. pilot and a 215 lb. passenger.
>> I calculated the CG as follows:
>> Nose = 13.634 kilos
>> Right = 125 kilos
>> Left = 117.3? kilos
>> 13.334 x 146 = 1991/255.9 = 7.77 cm. Forward of datum.? So my nose is light
>> due to the light engine, but for some reason, my overall weight does not
>> seem light.?? Is that acceptable?
>> My 13 lb. 18 amp battery is behind the seat as far forward as possible. I
>> guess I could get a lighter battery or mount it behind the engine.
>> My speeds are alot higher than Xair specs show.? The plane climbs at about
>> 500 fpm, at about 50 to 55 mph which, I guess is okay for a hot day, and a
>> heavy load.? Cruise is about 60 to 65 mph indicated at 5800 to 6000 RPM.
>> The plane stalls much higher than the 30 mph indicated in the factory specs:
>> about 46-48, no flaps.? The trouble I'm having is that:
>> 1. The flight numbers are higher than indicated by the manufacturer.
>> 2. When I throttle back to 5500, I quickly drop speed to around 55 or so and
>> I loose altitude.? I need about 5800 RPM to maintain level flight, and about
>> 6000 RPM for a slight climb.
>> 3. The engine overheats if I maintain 5800 RPM or better. I mean really hot.
>> 550+ CHT
>> EGTs are O.K. at about 1100.? I have an air dam on the front cylinder (as
>> recommended by Hirth because the plane is in a tractor congiguration) and
>> both cylinders read the same.
>> I talked to Stuart at Powerfin and he says I need more pitch to the prop, in
>> order to be able to have more thrust at lower RPMs.? He says myt static
>> thrust is good, but cruise thrust is probably inadequate to overcome the
>> plane's drag at cruise speed - especially when the plane is fully loaded.
>> He says I'll have to cut the prop from 68" to 66" to allow for more pitch
>> and allow the engine to develop full power. The Hirth 2706 is rated at 65 hp
>> at 6200 RPM.? Maximum torque is at 5700 RPM.? So the engine runs at a lower
>> RPM than the Rotax 582.? I asked Stuart if he thought I needed a lower ratio
>> gear box (like 2.59) and he said he didn't think that would help.
>> Questions:
>>???????? How does this compare with your 2 seat performance on the Xair at
>> gross weight using a Rotax 582 engine?? I know you like the 618, but how
>> does the 582 perform at Gross?
>>???????? Do you think the prop is running too slow because of the 3.16 gear
>> ratio? What ratio do you run with the 582. What prop pitch.
>>???????? What are your recommendations?? (I can't afford a 618 right now.)
>
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