Series 7 flying question.

[ridgerunner]

Since i'm new to flying a kitfox aircraft, has anyone experienced when your flying the left wing feels heavy? I don't know if this is normal when you fly alone due to pilot weight or if something is out of alignment. Any insight would be helpful and appreciated.

[Dave S]

Hi Les,

Real common to have a heavy wing on a newly assembled Kitfox. It's a matter of adjusting the washout.

You should find all the the info you might want by searching the forum with the term "heavy wing".

FWIW - the old aviation book titled "Stick & Rudder" explains this phenomena somewhere in the middle of the book.

Easy fix....:)

[efwd]

I spoke with John McBean about my heavy left wing when I started flying. It is very subtle. He thought maybe if it was as subtle as I described then I might leave the washout alone. I didn't touch anything and notice that its gone when I have a passenger.

[jiott]

I noticed a little of the same thing Eddie, but since I fly 95% of the time without a passenger, I went ahead and tweaked the washout to get level wings when solo.

[DesertFox4]

Jim expressed exactly my thoughts on the matter.
It’s been 15 years since I did the adjustment on my model four’s wings for a slightly right wing heavy condition. I know it’s been covered here before but if someone has recently done this very simple adjustment, feel free to post it again. This is a timely thread for many about to fly their first flights.

[ridgerunner]

Thanks for all of the reply’s on this. I am still amazed with the wealth of knowledge and experience that is shared on this forum. Glad to be a part of it. I am going to check everything and make any adjustments this weekend, thanks again.

[jiott]

FWIW, on the HEAVY wing, adjust the FRONT lift strut rod end OUT and/or the REAR rod end IN (this decreases washout which increases AOA to get more lift on that wing). You can also do just the opposite on the HIGH wing or a combination of both. If the heavy wing is quite pronounced, I would adjust one turn on both front and rear of the heavy wing; if that isn't enough do one turn on both front and rear of the opposite wing. John McBean told me you really shouldn't go more than two turns maximum on any one adjustment. As you close in on hands-off wings level, you will find only 1/2 turn is needed maybe in only one spot. You really don't want to change the washout on any one wing any more than necessary and as evenly side to side as possible because washout is what causes the wingtip to stall later than the wing root, a good thing. Going crazy with these adjustments can really affect your stall characteristics in a bad way. Personally, I prefer to increase the washout (decrease AOA) rather than decrease it if a lot of adjustment is necessary. If you have done a careful job of rigging the wings during your build, it really should not take much adjustment to correct for a somewhat heavy wing.

[efwd]

This could be totally off base but...
I would think that the wing that is climbing is the wing that I would expect to stall first. In my plane that is what seems to be in play. If I get any roll upon stalling it is to the right, which is the wing that likes to climb. I would think that this is where you would begin to make adjustments. In my case I had planned on turning my right wings forward rod end in about a half turn to remove a bit of the pitch. Would that make sense?

[jiott]

It makes sense to me Eddie. Yes, add a little more washout to the high wing (this decreases AOA and lift). In straight, level flight, the wing with the least washout (most AOA) should stall first. I am still of the opinion that if a small adjustment on both forward and rear struts is not enough, then you should go to the opposite wing and adjust there, so one wing is not changed too much compared to the other. Of course if a person gets worried about too much non-symetrical washout, you can always go back to the build manual instructions on wing rigging and get out your level and straight edge and actually measure it again and let the results guide you in any further washout adjustments.

[jiott]

Most guys that build a Kitfox seem to have a somewhat heavy left wing when the first fly it, from what I hear on this forum. I guess it makes sense because if you build a perfectly rigged, symmetrical airplane, you still have the built-in left turning tendency due to engine torque and other reasons we all learn about in our pilot training. I think the Kitfox build manual should recognize this fact and suggest that after you have finished rigging the wings symmetrically in the normal manner, THEN go and tweak each strut rod end say 1/2 turn to increase AOA on the left wing and decrease it on the right wing. By doing this when everything is exposed before covering it is a lot easier and many folks may not need to touch it when they start flying.

[jrevens]

I think John McBean gave an excellent description of how they adjust for a "heavy wing" at the factory (I believe it's posted somewhere on this forum), and that's how I attacked my slightly heavy left wing...

First check that you don't have a yaw issue that's causing the turn.

For a left turning tendency - adjust the right wing rear lift strut rod end out 1 turn (decrease the wash-out). Pre-flight and test fly after each adjustment.

If not enough, adjust the left wing rear lift strut rod end in 1 turn.

If still not enough you can start adjusting the front lift strut rod ends ... right one in first, and lastly left one out.

John wrote that you might only need 1/2 turn, or maybe as much as 1 1/2 turn... it depends on the severity of the roll rate.

It seems to me that doing the adjustments in this order should result in the least amount of necessary twisting of the structure on any one wing to get the desired result.

[jiott]

Good post John, however we need to clarify some nomenclature. If you adjust the rear rod end OUT, that Increases the washout because it is reducing AOA. Unless I am mistaken, washout is defined as the wingtip having LESS AOA than the root of the wing so it will stall later than the root. If I am wrong about this please advise.

[jrevens]

Thanks, Jim. Yes, I think you're right. I mostly copied that statement from John's post, but what he had actually written was "decreased twist (wash-out)"- sorry I don't know where it is in the archives of this forum, but I had copied and printed it a long time ago for reference. I interpreted his statement as saying that decreased twist was the same as decreased washout, which it isn't in this instance of course. The twist is actually increased by extending the rear strut rod end further out. I guess it would have been more correct to say "decrease the angle of attack of the tip", rather than "decrease the wash-out". Is that confusing enough for everyone? :confused:

[ridgerunner]

Thanks for the clarification on how to adjust the struts, saved me a lot of time searching for the info. I’ll check the measurements and adjust it this weekend. Thanks for the help.

[David47]

Does anyone do stall tests after these adjustments are made ?. Just interested to know how much/if they make much of a difference to handling ...

[Dave S]

David,

On first flight, noticed a slight wing heavy but entirely controllable - did one power off stall at significant altitude over the 'port in order to accurately determine what approach IAS to use for the first landing. That stall was the typical Kitfox gentle power off stall everyone indicates. Refrained from any more stall testing until the wing heavy issue was perfectly resolved so all stall series done in phase I, except for the initial one on first flight, was done after resolution of the wing heavy deal.

My thinking was to get the wing rigging right before continuing testing. The theory I was working off is get any observed anomaly corrected before continuing.

Now, had the wing heavy observation been extreme, I probably would have avoided doing a single stall test on the first flight.

As to your question - I am not sure that it is possible to compare one power off stall before getting the wing adjusted with the entire stall series after adjustment other than to say that all power off stalls with the kitfox have been gentle. Cannot address power on stalls since I had no intention of doing a power on stall on the first flight in any case.

Hope that helps some.

[jiott]

I did some stall tests after adjusting the heavy wing and could not tell any measurable difference, which was what I wanted to know. Unless you build a crooked airplane that takes a lot of heavy wing adjustment, I don't think the stall characteristics are affected to any noticeable degree. However, I like your thinking about fixing all flying anomalies before continuing the final Phase I testing.

[David47]

Thanks DaveS and Jim. Yes, my question probably relates more to the situation where larger adjustments were necessary, but I think you're right ... wing rigging or build symmetry would have to be way off for any noticeable stall behaviour changes.