Amphibian project resurrection & modifications

141 posts in this topic

Posted

Hi Ed, I'm not planning to us KF ribs on my current project. I will on the MK4, but that's on the back burner for now. I was just passing info along for anyone that is interested in the KF airfoil.

Share this post


Link to post
Share on other sites

Posted

Hi Ed, I'm not planning to us KF ribs on my current project. I will on the MK4, but that's on the back burner for now. I was just passing info along for anyone that is interested in the KF airfoil.

Luke - It don't take much to confuse me - anyway the prior post I made about flaperon hanger tails/brackets would apply to any plane.

EDMO

Share this post


Link to post
Share on other sites

Posted (edited)

If you really wanted drooped tips I have a set of brand new ones here still i two pieces so you could make them fit any profile $75 bucks and shipping and there yours.

 

drooped 002.JPG

Edited by TJay
1 person likes this

Share this post


Link to post
Share on other sites

Posted (edited)

If you really wanted drooped tips I have a set of brand new ones here still i two pieces so you could make them fit any profile $75 bucks and shipping and there yours.

 

drooped 002.JPG

Hi: T jay:

 

Thanks for the offer.  I'm still working out what I'm doing so no tips needed yet. I think my wing is going to end up looking a lot like an S7 sti wing in a long wing version with a sponson under it (this might change by tomorrow). On a side note as I've been researching different wings and wing builds the wings your working on look great exteramely detailed fit and finish work!!!

Edited by lukemn

Share this post


Link to post
Share on other sites

Posted

If you really wanted drooped tips I have a set of brand new ones here still i two pieces so you could make them fit any profile $75 bucks and shipping and there yours.

 

drooped 002.JPG

Hi: T jay:

 

Thanks for the offer.  I'm still working out what I'm doing so no tips needed yet. I think my wing is going to end up looking a lot like an S7 sti wing in a long wing version with a sponson under it (this might change by tomorrow). On a side note as I've been researching different wings and wing builds the wings your working on look great exteramely detailed fit and finish work!!!

TJay,  You should list the tips in the For Sale section - someone might see them and want them.  EDMO

Share this post


Link to post
Share on other sites

Posted

Hello, just found this forum and I have an Avid Catalina conversion and now reconverting to subaru engine.

Don

1 person likes this

Share this post


Link to post
Share on other sites

Posted

Hello, just found this forum and I have an Avid Catalina conversion and now reconverting to subaru engine.

Don

Don,  You have an interesting project going on - Post up some specs and photos in the Avid section.  We have a couple of Cat builders on here, and a few Soob flyers too.

EDMO

Share this post


Link to post
Share on other sites

Posted

Hello, just found this forum and I have an Avid Catalina conversion and now reconverting to subaru engine.

Don

Hi Don & welcome to the catlina section of the forum!!  It's great to have another cat builder with us.  Pictures are great when you have time.

Luke

Share this post


Link to post
Share on other sites

Posted (edited)

Working up an oil cooler mount.

20150927_180703.jpg

20150927_180555.jpg

20150927_180543.jpg

Edited by lukemn

Share this post


Link to post
Share on other sites

Posted (edited)

So there's been some thoughts / concerns about prop rotation direction.  The 912 prop rotates opposite of the direction of the 582 with a gearbox reduction installed on it.  I missed the change in direction when I  worked up a plan to install the 912 so this brings up the question were the tail or vertical different from Avid on 912 vs 582 amphibian airframe's or is the 912 instlation accomplished via engine mount and rigging.  

Just out of curisioty is the tail / vertical on other Avid or Kitfox modles diffrent 582 vs. 912?

Luke

Edited by lukemn

Share this post


Link to post
Share on other sites

Posted

Just out of curisioty is the tail / vertical on other Avid or Kitfox modles diffrent 582 vs. 912?

I don't know about others, but I can tell you that my model C with the 582 has a very obvious amount of "left rudder" build in to the vertical fin. Where the forward tube of the fin intersects the cross tube it's definitely not in the middle. On my mark 4 I think it's pretty much neutral, but I could be remembering wrong on that one. I haven't looked at that one in a while.

Share this post


Link to post
Share on other sites

Posted

I've been reading up on the vertical stabilizer off set and it looks like I'm going to need to make some changes to the tail.  Not too sure how I'm going to do this.  Maby offset Ribs and some angle to the engine? / cut the tail off and reweld it in? (Seems like a lot of rework) / Scrap it and order a new Just super stol kit? (This choice is starting to look alot better lately)

 If reworking the tail what mods make sense? I found a link on the site that detailed an extensive tail rework project on an early Avid using vortex generators and increasing the tail size if I can find the link above I'll add it to this thread.

Luke

Share this post


Link to post
Share on other sites

Posted

Just out of curisioty is the tail / vertical on other Avid or Kitfox modles diffrent 582 vs. 912?

I don't know about others, but I can tell you that my model C with the 582 has a very obvious amount of "left rudder" build in to the vertical fin. Where the forward tube of the fin intersects the cross tube it's definitely not in the middle. On my mark 4 I think it's pretty much neutral, but I could be remembering wrong on that one. I haven't looked at that one in a while.

Thanks Luked for checking it out!

I looked my amphibian over today and the tail offset is very easy to see.  I understood the rotation of the 582 but didn't take the 582 with optional gearbox installed reversing prop rotation into account when planning the conversion.  I'm working on how to mod the tail or if it's worth continuing with the project.

Luke  

Share this post


Link to post
Share on other sites

Posted

Don't get to overly concerned. it is not very difficult at all to change the tail. I did not do it myself but it cost just a hundred dollars. I  watched the professional builder set it up and it looked very easy. Much easier than an engine mount. Run a string down the center line and extend or shorten tubes to get degree of incidence you want. Mine is straight now. I may change a little one way or another after first test flight if trim tab won;t be enough. This guy was the builder and designer for The Little Buzzard and they designed in  an adjustable Vertical stabilizer to fine tune handling. I just wanted everyone to remember the whole aircraft works as a unit when making modifications. Safety is control.

2 people like this

Share this post


Link to post
Share on other sites

Posted (edited)

Don't get to overly concerned. it is not very difficult at all to change the tail. I did not do it myself but it cost just a hundred dollars. I  watched the professional builder set it up and it looked very easy. Much easier than an engine mount. Run a string down the center line and extend or shorten tubes to get degree of incidence you want. Mine is straight now. I may change a little one way or another after first test flight if trim tab won;t be enough. This guy was the builder and designer for The Little Buzzard and they designed in  an adjustable Vertical stabilizer to fine tune handling. I just wanted everyone to remember the whole aircraft works as a unit when making modifications. Safety is control.

Hi Don:

Sounds a whole lot easier than what we we're coming up with!  It looked like we'd be removing and replacing everything upper longeron to tail post to correct the offset.  The adjustable vertical stabilizer sounds interesting if you have time some pictures of it would be great.  The hardest part of the engine mount was locating the propeller flange after that it's filling in the space with tube work little bit of layout involved but easy to do.  How far along are you with the subaru install?

Thanks Don

Luke

Edited by lukemn

Share this post


Link to post
Share on other sites

Posted

I don't have an adjustable stabilizer on my craft. I was referring to The Lil Buzzard that has one on later models. They wanted an aircraft design that could be built for any engine. I wish I had taken the time and money to design one for a mine. At the time of recover I knew that I was going to change engines. I used the old fashioned method of grasping the tail and bending it forcibly to take out small amounts of deflection. The amphibs do not have as large of need for perfect vertical stabilizer as they are a pusher configuration and don't have the same P-factor as a tractor. I can't get to my aircraft at this time to figure out what tubes they had to lengthen and shorten but it was just a few of the ones that held the center tube going up to the main center tube that shapes the rudder and  stabilizer. I am already covered so it is difficult to see anything. A little adjustment did a lot. Now if you can get a picture on here of straight down to the rear from the center of the plane showing the tubes at the root.

Share this post


Link to post
Share on other sites

Posted

 I was using a 670 reworked in these pictures, real light and lots of power but almost no reliability. Take off was no more than 200 ft, cruise was 85mph Not a clue on rate of climb but fast. Big problem was landing as it did not want to leave ground effect so I had to fly it into the water instead of doing a flare.  I was scared to take it  to far from a landing location. I think it has too much lift. Heavier engine may help that.  I am back into pieces now getting rid of weight like heaters and such, Relocating battery and eliminating back seat to accommodate extra weight of the Subaru. I can add weight if needed instead of trying to have everything at first. Also added an electric landing gear I saw on that red avid in Ontario California, Casey Curtis I believe was his name. !00 times better than the old finger pinching unreliable manual. I will get some pictures of the doors. They came with the plane when I bought it but were made of fiberglass and I made new ones out of aluminum that worked way better.

Don, I hope you don't mind, but you are going to be a wealth of information for us on these planes so I am going to bust your pictures and post out into a separate thread here.  Can't wait to see pictures of your progress with the subie.  If I didn't have plans to hang my 800 on it I would be thinking about the subie as well, I have been VERY impressed with how well Rady's plane performs with it.

 

:BC:

Share this post


Link to post
Share on other sites

Posted (edited)

I don't have an adjustable stabilizer on my craft. I was referring to The Lil Buzzard that has one on later models. They wanted an aircraft design that could be built for any engine. I wish I had taken the time and money to design one for a mine. At the time of recover I knew that I was going to change engines. I used the old fashioned method of grasping the tail and bending it forcibly to take out small amounts of deflection. The amphibs do not have as large of need for perfect vertical stabilizer as they are a pusher configuration and don't have the same P-factor as a tractor. I can't get to my aircraft at this time to figure out what tubes they had to lengthen and shorten but it was just a few of the ones that held the center tube going up to the main center tube that shapes the rudder and  stabilizer. I am already covered so it is difficult to see anything. A little adjustment did a lot. Now if you can get a picture on here of straight down to the rear from the center of the plane showing the tubes at the root.

I'll get some pictures of it this weekend sooner if time permits.  The idea of P-factor being less of a factor in a pusher configuration than in a tractor configuration is going to take some head scraching for me to figure out seems backwards from my initial thoughts about it but that's the learning part of amature building.

Edited by lukemn

Share this post


Link to post
Share on other sites

Posted (edited)

You have all got me to scratching my head and fingering out the P-factor:  I would think it would be less for a prop in mid-ship than on the nose, OR, would it take more rudder power to counteract since the prop is closer to the tail?  The right-turning Soob is just like all the old Conts and Lycs - right prop, right rudder.   The left-turners get left pedal.  A right-turner backward is really a left-turner, but looks like it will put more circular air on the VS and HS to bank left, but pressure under each wing should be the same, but the P-factor of the prop should still be right?  .....Sooooo  ???   Guess you just keep it straight with whatever pedal you need to use!    EDMO

Edited by EDMO
1 person likes this

Share this post


Link to post
Share on other sites

Posted (edited)

You have all got me to scratching my head and fingering out the P-factor:  I would think it would be less for a prop in mid-ship than on the nose, OR, would it take more rudder power to counteract since the prop is closer to the tail?  The right-turning Soob is just like all the old Conts and Lycs - right prop, right rudder.   The left-turners get left pedal.  A right-turner backward is really a left-turner, but looks like it will put more circular air on the VS and HS to bank left, but pressure under each wing should be the same, but the P-factor of the prop should still be right  .....Sooooo  ???   Guess you just keep it straight with whatever pedal you need to use!    EDMO

Throw in the inverted "flying tail"  and I'm approaching being completly lost.  The elevator has some offset left to right that I'm guessing will need to be adjusted to deal with the reversed prop wash so it will trim out correctly. I need to move and reweld in the dorsal tube and that gets things in the correct places. (I think?) Some where on the site there's a link to a write up about optimizing the early avid tail desgine hopefuly I can find it againe just to help with getting the basics right.

Edited by lukemn

Share this post


Link to post
Share on other sites

Posted (edited)

You have all got me to scratching my head and fingering out the P-factor:  I would think it would be less for a prop in mid-ship than on the nose, OR, would it take more rudder power to counteract since the prop is closer to the tail?  The right-turning Soob is just like all the old Conts and Lycs - right prop, right rudder.   The left-turners get left pedal.  A right-turner backward is really a left-turner, but looks like it will put more circular air on the VS and HS to bank left, but pressure under each wing should be the same, but the P-factor of the prop should still be right  .....Sooooo  ???   Guess you just keep it straight with whatever pedal you need to use!    EDMO

Throw in the inverted "flying tail"  and I'm approaching being completly lost.  The elevator has some offset left to right that I'm guessing will need to be adjusted to deal with the reversed prop wash so it will trim out correctly. I need to move and reweld in the dorsal tube and that gets things in the correct places. (I think?) Some where on the site there's a link to a write up about optimizing the early avid tail desgine hopefuly I can find it againe just to help with getting the basics right.

Luke,  According to Kitfox, one side of the elevator trailing edge is fixed at 1/2" higher than the other side to prevent flutter - I cant remember which side is higher, but it probably don't make much difference.  I have absolutely no knowledge of the Cat tails.  EDMO

Edited by EDMO

Share this post


Link to post
Share on other sites

Posted

You have all got me to scratching my head and fingering out the P-factor:  I would think it would be less for a prop in mid-ship than on the nose, OR, would it take more rudder power to counteract since the prop is closer to the tail?  The right-turning Soob is just like all the old Conts and Lycs - right prop, right rudder.   The left-turners get left pedal.  A right-turner backward is really a left-turner, but looks like it will put more circular air on the VS and HS to bank left, but pressure under each wing should be the same, but the P-factor of the prop should still be right  .....Sooooo  ???   Guess you just keep it straight with whatever pedal you need to use!    EDMO

Throw in the inverted "flying tail"  and I'm approaching being completly lost.  The elevator has some offset left to right that I'm guessing will need to be adjusted to deal with the reversed prop wash so it will trim out correctly. I need to move and reweld in the dorsal tube and that gets things in the correct places. (I think?) Some where on the site there's a link to a write up about optimizing the early avid tail desgine hopefuly I can find it againe just to help with getting the basics right.

Luke,  According to Kitfox, one side of the elevator trailing edge is fixed at 1/2" higher than the other side to prevent flutter - I cant remember which side is higher, but it probably don't make much difference.   EDMO

Thanks edmo

1/2" is about what the offset is flutter makes sense so no adjustments needed hopefuly.

Luke

Share this post


Link to post
Share on other sites

Posted (edited)

While you’re leveling off at cruise altitude, the forces of discharge air and P-factor still exist, but they are diminished because of reduced power. Here, the airplane designer  (which is you now) provides a corrective force: the left wing or right wing is rigged so that it develops slightly more lift at cruise speed than the other wing, offsetting the left or right-turning tendency. ( this can be adjusted with the left strut assembly) Now with an extreme condition you can add another strut assembly to the right side. The vertical fin is also slightly offset, so that at cruise speeds the push of discharge air on the left side or right side of the tail surfaces is corrected for. ( there are four aprox 40' angled supports for the stabilizer main tube that should be reversed or equaled to set correct fin angle which can be varied according to various drag problems that are unknown( exhaust, radiator location,etc.) This is why I went with straight for mine. These are just modifications to do flight tests and adjustments will likely have to be made after a few flight and taxi tests. Even a few static runup tests will show some adjustments needed to balance the aircraft.      These corrections are exactly effective at only one cruising airspeed: go faster or slower and aileron or rudder trim will be required. Engine adjustment may also be necessary so now is the time to add these features. Now to say that I know what I am doing is wrong and do not take anything I say as right. That is why I am here, To check what I have learned with others.

Edited by Don
2 people like this

Share this post


Link to post
Share on other sites

Posted

While you’re leveling off at cruise altitude, the forces of discharge air and P-factor still exist, but they are diminished because of reduced power. Here, the airplane designer  (which is you now) provides a corrective force: the left wing or right wing is rigged so that it develops slightly more lift at cruise speed than the other wing, offsetting the left or right-turning tendency. ( this can be adjusted with the left strut assembly) Now with an extreme condition you can add another strut assembly to the right side. The vertical fin is also slightly offset, so that at cruise speeds the push of discharge air on the left side or right side of the tail surfaces is corrected for. ( there are four aprox 40' angled supports for the stabilizer main tube that should be reversed or equaled to set correct fin angle which can be varied according to various drag problems that are unknown( exhaust, radiator location,etc.) This is why I went with straight for mine. These are just modifications to do flight tests and adjustments will likely have to be made after a few flight and taxi tests. Even a few static runup tests will show some adjustments needed to balance the aircraft.      These corrections are exactly effective at only one cruising airspeed: go faster or slower and aileron or rudder trim will be required. Engine adjustment may also be necessary so now is the time to add these features. Now to say that I know what I am doing is wrong and do not take anything I say as right. That is why I am here, To check what I have learned with others.

Thanks for the info Don!!

Centring up the dorsal tube and adjusting rigging latter on sounds good to me.  I'll post some pictures this weekend of the tubes I'm thinking need to be moved. I was planning on making new lift struts for the plane already so maybe it's a good idea to make both sides adjustable like kitfox ones are?

Luke

Share this post


Link to post
Share on other sites

Posted

image.thumb.jpeg.cce040b50d59e486725ac3cimage.thumb.jpeg.c0bcd94749311c6b852f6e0image.thumb.jpeg.ccb15e3354565162ce110efimage.thumb.jpeg.5fdb06ad43903b91a46d80bLuke and Don   Thought you might be interested in a project Dean W. Is doing now, he is modifying the original (proof of concept wheels only) Catilena. The original owner put over 2000 hrs on it with a 532, now the current owner wants to make it into an amfib. As well as changing engines, 85 cont. increasing GW, adding 12 inches on each side of the hull etc. Today it was upside down but I took some pictures anyway, you can see where he moved the dorsal tube over (at the "4") and on back,added a couple of vertical tubes, heated the vertical fin attach points to release stress etc. Anyway Dean said if he could be of any help, call him. Usually lunch time 12:20-1:00 pacific will catch him. 509-758-3269.image.thumb.jpeg.bd2c90ff53ae0940161f125

image.jpeg

image.jpeg

2 people like this

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now