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Fat Avid weight and balance

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Posted

Doug, or anyone,

      Do you know what cowl Airdale used for the Stratus EA-81?  I have one of the smooth cowls, but not sure what it is (Raven - Kitfox - Aftermarket?)

I may be looking for another cowl after I find out how much it takes to make this one work on my FF.

EDMO

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Posted (edited)

Ed - the Airdale was designed for the Sube FWF and I believe only one cowl option was offered. It had two round nose openings and there is a pic in this thread > http://www.avidfoxflyers.com/index.php?/topic/1325-airdale-build/

 

You can also see an Airdale Flyer cowl in the pics here > http://members.core.com/~flyboy/airdale.html

 

Note, this is NOT the same cowl as shown on the www.Airdale.com website under the [Airdale Flyer] link (which then directs to an Airdale 'Backcountry' (which used to be called the Airdale Flyer by the previous owners and was renamed by Brett?). Link > http://www.airdale.com/airdale.htm

 

HTH :BC:

Edited by dholly

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Posted

The cowl was wider than needed but I just made a wider firewall and got the fat avid even fatter lol

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Posted (edited)

Ron Smith (other Cowl thread) has the Airdale cowl mold. The one and only as far as I know. It has two different fronts he can mold into it, presumably for differnet engine options. here are the pictures he sent me. He said he would pull the molds out if we need more detailed pics. Keep in mind thes are molds not cowls, so you have to use some imagination.

Ron is contacting Jerry Mattison(sp?) to get more details and is going to get back to me.

I am currently trying to find out how much different the Airdale flyer is than the Flat Avid WRT cowl meeting windscreen and fuselage.

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Edited by ChrisB

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Posted

Thanks guys for the Airdale Soob cowl info - If I cant make the Raven / Kitfox work, then this looks like a possible fit.

EDMO

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Posted

Great to know Chris! Me thinks Ron Smith might suddenly see his Tomash judgment spoils paying dividends again soon. Just hope he is reasonable with his prices if he decides to put them to use and sell direct. Some KF parts prices are through the roof crazy, at least Ron is not trying to fund an aircraft co. in increasingly litigious times.

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Posted

Well got a few more flights on the avid today after we shimmed up the lower motor mounts to get prop 90 degrees to the thrust line, it was low about 2 degrees  and helped quite a bit on the amount up upward pressure on the elevator. Unfortunately it didn't get rid of it totally. We are now thinking of trying to lower the leading edge of the horizontal stabalizer.Question for Randy or any other avid plus guys.Just wondering if you know what hole the front of the  hortizontal  stab is bolted to,I can see one hole above for adjustment but not sure if there is one below,maybe its cover in fabric if there is three oprtions.Also the horizontal stab struts look like there pushing the forward stab up and pulling the back down,im pretty sure these were off his avid c ,just wondering if you guys  used the old struts or had to make new ones,

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Posted (edited)

No engine offset? If you read the Pursang history HERE, Dean Wilson recommended 3* degrees offset to thrust line to counteract P-factor and torque, and 1.5-2* degrees down thrust for the Sube.

My KF3 had (3) holes for H.S. adjustment. When I got it it was in the bottom hole, I moved it up to the middle hole to raise the tail. On my Avid+, there is room for only (2) adjustment holes. When rigging my H.S., I kept the angle of incidence equal to the door sill which I believe to be the same as the thrust line. Thrust line is not identified in my Avid build manual, but that's the way Kitfox is so I went out on a limb and ASSumed. If I cork it in on the test flight tell the FAA it was a contributing factor...

 

[edit] add pics

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Edited by dholly

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Posted

Hey Doug thanks alot for that info,it was about 2 degrees down but it seem to pull the nose down when I hit the throttle which really felt wrong,when i pulled back on the throttle the pressure on the elevator was reduced ,by shiming the angle up  it helped quite a bit but is a long ways from hands off in cruise, I still need constant up pressure on the stick. I think my avid only has the 2 holes also and maybe  the horizontal stab struts are pushing up enough to cause the problem, more testing i guess

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Posted

Well I guess that stands to reason, seeing that both a Sube-powered Fat Avid upgrade or Avid+ would be a bit lighter and *I think* a bit shorter than John Larsen's Mk-V Pursang. As far as the H.S. struts, mine have no tendency to warp the H.S. itself. IIRC, the H.S. and elevator supplied with my Avid+ kit were entirely flat, whereas the H.S. on my Mk-IV did have some twist built in. I know this topic has been discussed on at least one of the Avid/KF forums, if you search the respective archives you might find something of interest. I can measure the H.S. or struts I have if you need, just let me know.

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Posted

Willis,

 

I only had one mounting hole in the front and one in the rear for the HS on my Avid+ airframe.  Looking at Doug's pictures, it looks like mine is located in what would be the upper hole of Doug's frame.  I used the HS from my Avid MKIV and it is flat.  I mounted the struts to the HS and adjusted the angle a little with washers until the bottom mounting position lined up well with the tab on the airframe, made sure the HS was square to the airframe and then clamped it and drilled the holes for the bottom bolt in the tab.  No warp in the HS at all.

 

Mine flies hands off easily for as long as you want to if the air isn't too turbulent but the trim changes some depending on how heavily loaded it is and where the weight is.  I have the trim on the HS set so there is plenty of trim range when I have a normal light solo load but if it is heavy I have to pull an additional notch of flaperon so I have enough trim range on the HS to fly hands off.

The fact that you are still having the engine power affect your stick pressure makes me think the area that still needs some tweaking is the engine thrust line.  Mine has no tendancy to pull the nose down with full power; it tends to pull the nose up a little, but not too strong or abrupt.

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Posted

Hey Randy , its good to know yours can fly hands off,raising the angle of the motor diffenently got rid of alot of the back pressure on the elevator,the HS struts came off a model C , and diffenently warps the forward of HS up and the rear down.I dont have a trim  on my avid but looks like i'll be trying to install one,hopefully I can do something  with a cable,thanks for the info

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Posted

Randy , would you have a picture of your trim tab by any chance and were you placed it

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Posted

I don't have a real good closeup of the trim tab handy but you can see it in the attached picture.  It is the standard Avid MKIV trim tab and I am using an electric trim servo but think you coule rig it up for cable operation just as well.

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Posted (edited)

Unless you want an IFA trim tab, and want to rebuild your elevator, then a small 2"x6" flat aluminum tab riveted to the inner part of the elevator trailing edge is the easiest - just add it and guesstimate a 5 degree bend to start with, then fly and straighten or add more bend as you need.  Bend it opposite of the way you want your nose to go.

EDMO

Edited by Ed In Missouri

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Posted

Thanks Randy and Ed ,gives me some idea were to start, thats an awesome picture of the avid with the mountains as background

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Posted

Willis - here's the page from the Avid manual on how to retrofit electric elevator trim plus a few pics from my Mk-IV that might help. I canned the manual bowden cable and ran nylon tubing through the cable bushings as a protective chase for the servo wiring.

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Posted

I don't really care for the electric trim tab - guess it is OK if you have an indicator of some kind - I designed mine for manual trim tab - got a servo that I would sell tho.

EDMo

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Posted

Thats awesome Doug thanks , I first got to get my HS level then I will see what I can and cannot do,more than likely will be doing some sort of manual trim since its all cover up , gives me a good idea how its suppose to go though. Thanks again

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Posted

Well I got my horizontal stabilizer straight  and it helped quite a bit but still needing back pressure on the stick to fly level, I am wondering if the kitfox cowl I fit on has to much downward tendancy, my computer with the pictures of the plane packed it in so waiting to get it fix so I can't post any new pictures but if you look at  the pics in the previous post let me know what you guys think. I was wondering if its a bad idea to fly the plane without the cowl on it, that way I could tell if my theory is correct,just not  sure if there would be any problems doing this for a short flight

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Posted

Rivet a small trimtab to the elevator and bend it down slightly and try flying with it.

EDMO

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Posted

1. Are your flaps fully retracted?

2. Can you adjust the position of the front mount bolt for the horizontal stabilizer?

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Posted

I agree with trying a piece of aluminum as a trim tab. It's an easy fix to see what's going on. I'm very curious of the progress on this. As with any changes on an aircraft it's sometimes hard to know what little change might make a big impact. That's why I try very hard to only make one change at a time.

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Posted

Im pretty sure the flaps are fully retracted and at  degrees-3 when fully off, there is 2 adjustment holes for the horizontal stab but im in the lowest hole right now, was thinking also of try to drill one more hole lower but not sure theres enough room for that. Just figure that it must be something else since there a few avids with the soob flying and not seeming to have this problem. I will probably try the trim tab but would like to figure out the problem ,in case its just the angle of my cowl. In level flight it diffently has a nose down attitude

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Posted

How about adjusting your flaps for - say -5 degrees?

EDMO

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