My Avid MK Aerobatic Speedwing build advice

8 posts in this topic

Posted

I would like to ask the community a few question that I previously asked on the facebook site. I am an 18hr student pilot and am debating on whether my plane needs more reconfiguring, to make it more safe, before closing her up and hauling her to a training field. I have not flown the plane so I only have 3rd hand knowledge about the plane's flight characteristics/safety margin.
 

On the fb site, I have received some alarming feedback from a respected pilot and owner of a speedwing. Being that I am not interested in making too many life endangering mistake, I am looking for advice. Please note, I can fabricate or spend money if need be. 
 

 For those that don't know, I have a Jabiru 2200, a 7 inch wider homemade TD landing gear, an 8" Matco Tailwheel, and I kept the plane as light and streamlined as possible for a reasonable speed envelope. I have the PC545 battery in the rearmost part of the plane. 

Now for the questions. I am an 18 hour (in a Cessna 152) student pilot. I plan on training, in my MKIV Aerobatic Speedwing, with a CFI to obtain a Sport Pilot license. 

Question 1: I have been told (from someone I respect that owns one) the Speedwing is from the devil as they can drop right out of lift when you may not expect it. Should I change the wing? I hate asking this question before flying the plane, but I am just looking for the opinions of more experienced pilots.

Question 2: Are the tail feathers adequate? I have heard they are, but again, looking for more opinions from the "experienced". Should I add length to the fuselage? I can weld 4130 tubing.

Question 3: I am in the US and will use non-ethanol Mogas (benzene + additives??). Should I mod my stock wing tank and other fuel system components? 

Question 4: I plan to gravity feed fuel to the Jabiru carb (no factory pump either), while employing an "as needed" inline fuel pump for takeoff, landing, and oh crap situations. Any thoughts on that? How about fuel pump, hoses, etc? What if ethanol gets in there due to an erroneous gas station? How can I "harden" my system to protect me? 

Just a few questions for those that feel inclined...

Thanks!

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Posted

I can't answer all of your questions but will have a shot at the ones I think I can.

1) Never flown a speed wing, but cant imagine they would be horrible. Maybe touch down just a bit faster. I would NOT change the wing.

2) Tail feathers are adequate for the STOL wing. Can't imagine them not OK for speed wing.

3) Non-ethanol auto gas is what you want to use. You will not have tank problems with non ethanol. You could have tank problems with ethanol depending on type of fiberglass they are constructed with.

4) If the carb is on the bottom of the engine it will work fine with gravity feed as long as you use proper gascolator, header tanks etc, that will not restrict fuel flow. if the carb is on top of the engine (sorry i don't know) you will want a fuel pump becuse at high angles of attack it may be possible to starve the engine of fuel. DO NOT USE ETHANOL and you won't have any ethanol problems.

If your plane is ready to fly now after a good inspection, fly it the way it is before you make any changes. You will then be making changes if you make them from a perspective of understanding. Dean Wilson is a phenomenal designer and knew what he was doing. Fly it stock before you mess with it.

I do recommend someone who has a lot of time in Avids, Kitfoxes etc as your instructor. or at least to teach you to fly it before getting "instruction". Not all instructors are proficient in short coupled low inertia airplanes like Avids and Kitfoxes.

They are AWESOME planes! 

 

 

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Posted

For what it's worth, I am an 80 hour pilot, all in a Cessna 150.  I had the opportunity to take the controls of a Kitfox 4 1050 and had a very hard time flying it.  They mean it when they talk about using your feet.  After maybe 1/2 hour I stared feeling slightly more comfortable but it was a huge wakeup call.  I now have a person lined up with a lot of experience, Kitfox and otherwise, who will do the initial test flights and will transition me.  Point is, be ready for that and remember that I have yet to hear from a Kitfox pilot who doesn't love them.  Hopefully I will be one of them soon.

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Posted

On the fb site, I have received some alarming feedback from a respected pilot and owner of a speedwing. Being that I am not interested in making too many life endangering mistake, I am looking for advice. Please note, I can fabricate or spend money if need be. 
 

 

I would like to caution you on the Speed wing.  Nice plane but read this post from a fellow member that had a motor out.  Just read the first post.

http://avidfoxflyers.com/index.php?/topic/5597-engine-failure-yesterday/

I had a speed wing and can confirm the same numbers.  There were some that claimed putting the extensions on the speed wing made it a reasonable plane.  Good flying qualities and still good speed. 

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Posted

On the fb site, I have received some alarming feedback from a respected pilot and owner of a speedwing. Being that I am not interested in making too many life endangering mistake, I am looking for advice. Please note, I can fabricate or spend money if need be. 
 

 

I would like to caution you on the Speed wing.  Nice plane but read this post from a fellow member that had a motor out.  Just read the first post.

http://avidfoxflyers.com/index.php?/topic/5597-engine-failure-yesterday/

I had a speed wing and can confirm the same numbers.  There were some that claimed putting the extensions on the speed wing made it a reasonable plane.  Good flying qualities and still good speed. 

That is sobering... I may need to add a little length to the wings....

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Posted

I have heard that the extended speedwing is a great flying airplane and it was something I always wanted to try.  Others said the washout on a simple extension would be to much, but to be honest I never sat down and worked it out.  I think it's an idea that should be checked into.  I know with the twenty four foot wing a lot of energy is spent keeping the plane in the air instead of getting the speed you should be able to get from a small light plane. 

 

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Posted

I am considering this Norm. I am also considering altering the twist by tweaking the lift struts. 

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Posted

I have heard that the extended speedwing is a great flying airplane and it was something I always wanted to try.  Others said the washout on a simple extension would be to much, but to be honest I never sat down and worked it out.  I think it's an idea that should be checked into.  I know with the twenty four foot wing a lot of energy is spent keeping the plane in the air instead of getting the speed you should be able to get from a small light plane. 

 

Hey Norm, what if one removed some of the washout, via the helm joint (and another on on the other side), then added say 2 feet of wingspan per side, and topped off with really good wing tips? Coupled with a decent catering cost wheel setup (maybe with a Grove gear), I am thinking, if kept light and balanced, this could be a cool cruiser under the power of a Jabiru 2200. What do you think?

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