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Avid MK4 thrust line

7 posts in this topic

Posted

Hi group,

Can anybody advise if the thrust line on Avid MK4 models has a fixed location, or it can be offset up and down depending on the engine type.

Where is the point where the thrust line intersects the MK4 firewall,and does the line run perpendicular to the firewall ?

I have no cowl and mount yet. My manual does not say anything.

Thanks,

Dan

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Posted

Hi group,

Can anybody advise if the thrust line on Avid MK4 models has a fixed location, or it can be offset up and down depending on the engine type.

Where is the point where the thrust line intersects the MK4 firewall,and does the line run perpendicular to the firewall ?

I have no cowl and mount yet. My manual does not say anything.

Thanks,

Dan

I will run out to a buddies Mk IV tomorrow and pull some measurements for you. I am sure that with all the variations in engines, and cowlings you can get, there is no one hard fast thrust line. What engine are you planning on using?

:BC:

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Posted

Thank you Akflyer,

The engine will be 2000 Suzuki 1.3, 16 vlv. with a SPG gearbox 1:2.34.

I already spoke with Airdale. It looks like there is no exact location of the thrust line on Avid MK4. Some old forum threads indicate, it can vary up and down depending on the engine and cawling (except ~2 deg fix in horizontal plane to compensate for the P factor).

I assume, along the fuselage the thrust line is paralel with the tailplane, or is perpendicular to the firewall, but without drawings i have no proof of either assumption.

Any measurements will be of great help to me. Also, any input fro Kitfox MK4 will be very valuable.

Thanks,

Dan

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Posted

Thank you Akflyer,

The engine will be 2000 Suzuki 1.3, 16 vlv. with a SPG gearbox 1:2.34.

I already spoke with Airdale. It looks like there is no exact location of the thrust line on Avid MK4. Some old forum threads indicate, it can vary up and down depending on the engine and cawling (except ~2 deg fix in horizontal plane to compensate for the P factor).

I assume, along the fuselage the thrust line is paralel with the tailplane, or is perpendicular to the firewall, but without drawings i have no proof of either assumption.

Any measurements will be of great help to me. Also, any input fro Kitfox MK4 will be very valuable.

Thanks,

Dan

Hey Dan,

Sorry, I know I was spose to get the measurements for you, but I ended up with a few life altering changes at the house (got rid of the wife thing) and I did not make it out to the airport. I will be back in town on the 23rd and will get some numbers for you then.

:BC:

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Posted

On the earlier Avids the tail is offset from the fuselagenot sure on the Mark IV

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Posted

Dan - which do you have, Avid or KF? Thrust line is different because of inverted vs. plugs up, right? I'm attaching the specs for the Jab2200 engine and the mount for KF I-III. you can do the math to find C/L relative to the firewall and perhaps that will help. Note: the Jab2200 mount for an Avid is different, I could probably bolt my Jab2200 engine mount to my Avid+ and take some measures if you need for or want to compare thrust line to to the Avid firewall engine mount stations. Other info: Official Jabiru engine install manual states ~1* to 2* offset (in Jabiru aircraft install). Corrections of the engine alignment may be made using spacers under the rubber cushions. The maximum spacer thickness on any one mount is 3mm. Engine Mount Ratings : Upper & lower attachments: +6g and -3g. Hope that helps.

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Posted

Thank you for the drawings and the info on Jabiru mount.

My Avid is MK4 Aerobat.

Dan

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