Phoenix 8 trim problem
 

I need help from some of you expert.

I test flew the phoenix Pattern airplane the other day only to find out that it was badly out of trim. I had full up trim to keep it going.

and when landing came, it wanted to float foerever.

I found on the bench that the wing incidence was 1/2 degree negative. I corrected this and out I went today for another test flight.

Much better, Buuttttt, at half throttle, I trimed it for level flight, but when I power it up to full throttle, it wants to dive, then I trim, and then half throttle it is the opposite., I had a hell of a time landing it because it wanted to float forever. sign of tail heavy, and it is as neutral on the balance as I can get it.

HELPPPPPPPP

Thanks for any advice.

BTW, this thing is fast, very fast...

RE: Phoenix 8 trim problem
 

does the plane have retracts
if so balance it with the gear down
if not it sounds like it is tail heavy
vinny

RE: Phoenix 8 trim problem
 

Thanks Viny,
No it doesn't have retracts.

If its tail heavy which I think your right, what about the fact that I need a lot of up trim ?

Roger

RE: Phoenix 8 trim problem
 

Maybe too much engine down thrust, if it is trimmed level at 1/2 throttle and dives at full throttle.

Why not trim it to dive vertical in downlines and then setup engine down thrust accordingly.
Of course you should use plans C.G. as a starting point.


ini

RE: Phoenix 8 trim problem
 

Thanks,
This is very usefull information.

Roger

RE: Phoenix 8 trim problem
 

I agree with the down thrust being the majority of your problem.

RE: Phoenix 8 trim problem
 

Thanks, I will be doing some hard checking tomorow for sure.

Roger

RE: Phoenix 8 trim problem
 

Well here are my findings. Everything is set up properly at 0 degrees, stab, wing, and engine. Any other ideas?

I am waiting for the landing plate to set in glue, then I will reassemble it and again check the CG.

Thanks to everyone that has offered some help so far. I appreciate it.

Roger

RE: Phoenix 8 trim problem
 

Roger,

It sounds to me as though the plane might be terribly nose heavy. The reason I say this is that the P8 was originally designed as a trike gear ship and I have no idea how much that landing gear you put on it weighs, but I would wager it is making a big difference by where it is placed. If you are having to trim nose up at full throttle w/a O/O/O setup then you are nose heavy. Easy check??? Roll it inverted and see if she climbs. I bet it does. A P-8 does NOT like to fly slow at all and mine always felt "mushy" at slow speeds but very accurate at high speeds. Anyway, as others suggested, use the plans CG first as a guide... but when in doubt..roll her inverted and see if she climbs.. if so.. nose heavy. I seriously doubt you have a tail heavy bird with that tail dragger configuration. Hope this helps. I'm getting ready to build a new one.... hard to get away from a plane you really like.

Deadstik...[8D]


Carolina Custom Aircraft

RE: Phoenix 8 trim problem
 

Today, I just checked the cg and yes it is out. I installed some lead weight in the tail and very anxious to try again,

Again, I realy appreciate yours and everyone else's help on this.

Roger

RE: Phoenix 8 trim problem
 

So what happened on the next test flight?

RE: Phoenix 8 trim problem
 

Well,
I still need weight in the tail, even thought it was a bit better. The problem that I am having now it doesn't matter how smooth I land, the landing gear pulls out. So for now, I have put it on the shelf to finish my 34% Edge and then I will look into it.

The way my landing gear is made, it is not solid in the fuselage. And being Carbon Fibre, it doesn't absorb anything .

If any of you have good ideas about how to properly install this, let me know.

Thanks
Roger

RE: Phoenix 8 trim problem
 

It was interesting to read this information about the Phoenix 8. We are having similar problems with an old "recycled" 80's pattern ship. Trimmed for level flight at full noise the nose comes up alarmingly on landing approach and the plane refuses to settle in unless the speed can be washed off to the point that its barely flying. It runs No downthrust, though the indications are that it has exessive downthrust...strange??

RE: Phoenix 8 trim problem
 

Something worth trying.... trim for a small amount of droop on both ailerons and the down elevator trim to compensate... will tend to pitch the nose down at low speed. We will be shot down in flames over this one as it will mess up the tracking of the ship in other respects. it basically has the same effect as altering the wing/tail incidence.

Yeah....these things are fast....would'nt be the same if they were'nt

RE: Phoenix 8 trim problem
 

take a look at this link:

http://www.nsrca.org/trimA.htm

I think it might help you...

give us some news after your tests.

Wilker.

RE: Phoenix 8 trim problem
 

Can someone here post a picture of their Phoenix 7 or 8. I thought I had a 6, but have been told that the version 6 did not have the removable canopy with the area for the pipe, and that's what I have here. Many years ago I lost the information to the ship and have never completed it. Getting back into the hobby now and want to finish it off. Plan on putting the OS .91 in there insted of the original OS .60 with pump and pipe.

Thanks for the help.

Tommy

RE: Phoenix 8 trim problem
 

Here is a picture of the Phoenix 8. Precision Aero Composites still sells this plane.

RE: Phoenix 8 trim problem
 

What a great looking machine! Is it still flying?

RE: Phoenix 8 trim problem
 

It is not mine:(:(:(..... The picture is from the "Precision Aero Composites" web-site. It is a pretty looking machine!!!!!

RE: Phoenix 8 trim problem
 

Hey thank for the pic of the P-8. Well that's not my plane either. Mine, what ever it is, has a much larger stab and fin and the stab has the negative dihedral as per the F-4C Phantom. The canopy piece, which is pretty long and comprises the canopy and the cover for the pipe, goes from pretty close to the nose across the back of the fuse and is held down with #2 screws.

The fuse and this canopy piece is still in the green fiberglass as I haven't done anything with is. I will set it up and shoot several shots of it as it is and see if anyone had any ideas.

Thanks guys,

Tommy

RE: Phoenix 8 trim problem
 

Sounds like it could be the Curare from Hanno Pretner.

Roger

RE: Phoenix 8 trim problem
 

Tommy,

I'll bet you have EU1-A. Both the Phoenix 8 and the EU1A were manufactured by Aero composites. All it will take is a picture and we will get you a 100% answer. Ships w/anhedral stabs included the Curare, Magic, Illusion, and a lot of guys modified the EU1 ( I know I did.. everybody wanted to be Hanno). But, you may also have a Bridi designed Escape or one of his earlier designs that used a full length fiberglass combo canopy/pipe enclosure. Just send a pic and I'm sure you'll get the correct answer.


Deadstik,

Carolina Custom Aircraft

RE: Phoenix 8 trim problem
 

Deadstick,

Just got back from Atlanta. Thanks for the post. I plan on shooting a session in the moring on the plane I have, what ever it is, and will post a few images of it here to see who can do a Sherlock Holmes on it. It's a mystery to me so far.

I have never posted an image here and guess you use the Image buttom above to add the link. Do you have to upload the image to your server and then post the link via the image button, or can you just link to an image in a folder on your computer?? A little clarity on this would be appreciated. Did a search on adding images here on the forum, but didn't get anything. Probably searched for the wrong thing.

Also, about what size image in MB is used here? I know that I will have to downsize the image loads as the JPG's from our Canon bodies are 8.3 MG's out of the camera. A pretty large JPG file size. Info on this is also appreciated.

Deadstick thanks for the help and I know that with the forthcoming images you, or someone on the Pattern forum will nail this down.

Thanks a bunch.

Tommy

RE: Phoenix 8 trim problem
 

This is a test of sorts. Wanted to see if I had it down to insert an image into a post.

This is an image of a vintage GP CAP-21 circa 1980 or 81. Still flies great... but does live up to the name of Snappy Cap if you are not careful.
http://www.connellstudios.com/RC/Cap%2021_thumb.jpg
[link=http://www.connellstudios.com/RC/Cap%2021_web.jpg]Click to view full image[/link]

RE: Phoenix 8 trim problem
 

Here are some images of the so-called Phoenix. Hope some of you guys can figure out what it actually is.

Thanks for the help on the plane on getting images here correctly.

Tommy

RE: Phoenix 8 trim problem
 

What you have is a Hobby Barn Magic, also a Prettner design. I had one back in the late 70's, early 80's. It was alright, but it had a horrible pitch to the belly in knife edge flight. I never thought Prettner gave Hobby barn the right drawings!

RE: Phoenix 8 trim problem
 

Hi
Yes it's a Magic be sure on that, i have one of the kind, but build from an MK plan, never flown with it yet.

Regards
Kjeld Pedersen
Denmark

RE: Phoenix 8 trim problem
 

Tommy,

Tony and Kjeld are certainly right.. it's a Magic... matter of fact, I bought a hatori header for a YS 60 for one and never got the kit !!! Still have that puppy. It takes the R/E and puts it to the top of the fuse tunnel. At any rate, I'd certainly finish it...

Dan


aka deadstik....[8D]

RE: Phoenix 8 trim problem
 

Tommy,

Here is a pic of a completed one. I don't know who to give credit for the build to as it's just from my archieves. Pretty plane !!!

Dan

RE: Phoenix 8 trim problem
 

Thanks guys for all this information and confirmation as to what the plane is. For the life of me the name rings no bells at all. I wonder if I bought it as something else. Anyway, I plan on completing it this winter.

Dan, please point me to where I can get the information to correctly add photos to these post. I have seen lots of them side by side and where the actual thumbnail becomes the link to the larger image. Help on that.

Tommy

RE: Phoenix 8 trim problem
 

Tommy,

The key to adding photos to any post is that you cannot add photos to the "quick" response box at the bottom of the forum. To add a picture to your reply, you must first click on the "Reply" button on the post you wish to reply to. After you add whatever message you wish to send you will see a link at the bottom left of the response you are writing which says "Upload documents" When you click on that, another box will open up on your screen and you can select I believe up to 4 photos to add to that post. The pictures will not appear in your draft, only after they have been uploaded and the page refreshed. You do have to wait till the box says, "Upload Complete" Hope this helps.... good luck with the plane,


Dan.......[8D]

RE: Phoenix 8 trim problem
 

Dan,

Thanks for that information. I am trying to check that out here and will post an image with this reply.

Dan, think I've got it now. This is a picture of my Shoestring 1/4 scale and yours truly at the field for the second time in 22 years.

Thanks, Tommy

RE: Phoenix 8 trim problem
 

Hi everyone, I searched for phoenix 8 and the search led me to this forum. I have just completed the longest project that I started 30 yrs ago, this was my second airplane I started to build was the Phoenix 8. Well after 30 years it is just about ready to fly, finally, equipped with O.S. 61 FX and Kraft electric tri-gear retracts. My only concern is the balancing, it seems to be tail heavy, but I lost he plans long ago and don't know where the balance point is. Can someone help? How far back from the leading edge of the wing at the side of the fuselage? I also was wondering about the overall weight and if someone could offer their opinion on how it would fly, with this bird weighing in at 8 1/2 lbs. I am new at this but will try and post a picture.

RE: Phoenix 8 trim problem
 

Nice bird, Rule of thumb is 1/3 back from the leading edge of the wing at the root.

RE: Phoenix 8 trim problem
 

not in a swepback wing, be carefull
Roger

RE: Phoenix 8 trim problem
 

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A good place to start is to balance at 25% of the wing mean aerodynamic chord. Here is how to calculate that position graphically.

Draw the wing planform full size. Draw a line from one end of the tip chord to the opposite end of the root chord. Now measure the root chord and add it to the tip chord as per the sketch. Do the same with tip chord and add it to the root chord. Draw a line connecting the ends of these new lines as per the sketch. Where these lines cross is the Mean Aerodynamic Chord for the wing. Draw a line chordwise at this point. Measure back 25% along the M.A.C. Project this line onto the fuselage and this is where to balance the model.

This is a safe starting point which you can work back from.

Hope this helps

Malcolm

RE: Phoenix 8 trim problem
 

Dawg Pilot - I called a friend of mine who still has the plans for a Phoenix 8. The plans show a CG location of 6 3/4" back from the leading adge of the wing at the center of the wing.

Hope this helps,

Jon Carter

RE: Phoenix 8 trim problem
 

Alright you guys are outstanding. Thanks for the help it was just what i needed.
thanks!!

RE: Phoenix 8 trim problem
 

I am balancing right at 7" at the center of the wing, in my experience this would not normally be a problem, just want to be sure after all would hate to snap it in at landing with a plane that took 30 yrs to build.:D Any opinions?

RE: Phoenix 8 trim problem
 

I FINALLY got my Atlanta 60 up last week...old pattern ships rule! Bet ya my Atlanta with Rossi r/e on pipe kicks your 8's ass...lol....Super Fast...Rossi claimes 2.35 h.p...@17,000rpm...OMG!...Big_G