I am in a mell of a hess.

[Paul Taylor]

I got my Akrobat on wheels and just had to put the engine in today to see how it will look.
Much to my surprise the CG is no where on the wing! I put close to 3 oz of lead on the tail and was just getting close on the CG.

Looks like my shot at a light plane is going to be missed with this one too!  

[Wynn Robins]

chop the nose !!!!

what engine are you using? 

[Paul Taylor]

Just what you taught me to use.... them old blue engines. LA .46.

[Clint Ormosen]

You had to be expecting this. The Akrobat was designed with a much lighter Fox 35 in the nose. An unmuffled one to boot.

[Chris McMillin]

This is where people find out that when a model is drawn with a Fox 35 with no muffler and a nose as long as the tail moment, they have to shorten the nose. A good way to go on Sig kits is to move the F1 back as far as you can and still get the tank in (that is, bulkhead at leading edge, back of tank against it, then front bulkhead right up to the tank or with a plastic clunk tank, which is way lighter than a metal one, have the front end stick through a hole on the firewall bulkhead), then push the engine back as far as you can to the F1. Then drill the holes for the engine.

Add the tail weight and get it to balance, seal the hinge lines with clear tape and fly it the way it is. It'll be fine. Use the lightest spinner (Great Planes plastic cone shaped) and prop (wood two bladers are lightest), and prop nut (aluminum) you can find. You can't use that stock OS muffler either, it weighs a ton and is used to balance R/C models which are weighed in pounds, not ounces. Use a metal hubbed, 1 inch tailwheel, too.

Chris...

P.S. I flew my Golden Falcon for 1500 flights or so with the CG ahead of the leading edge. Many other flyers have done the same. It's not preferred, I assure you.

[Air Ministry .]

Cant be that much of a mess. Take the engine out ! Fit a Fox .35 !

Or two 15s on the wing . Must be a very light aeroplane .

Tungstens heavyer than lead ,

[Wynn Robins]

Just what you taught me to use.... them old blue engines. LA .46.

Good Man!!!!!  now chop the nose and put that engine back in there!

[Zuriel Armstrong]

Paul,

What is the total weight so far.  BTW...nice rudder

[Paul Taylor]

Well Wynn... this thing is so close to getting done. I don't want to move backwards on this project.

OK, so I can get a very light muffler, that will save some nose weight. Wood Prop should help.
3/4 in tail wheel maybe. Still need to put the flaps on so there is a little more weight behind the CG. Will use a clunk tank.
So if I am real lucky I will only have to add maybe 2oz to the tail. I feel a little better.

I was too depressed last night to put it on the scale.

And Zuriel, I am glad you like the rudder. Maybe you should put one on your plane.

[Zuriel Armstrong]

If I put one on it wil be on the bottom.  I always knock them off when they are on top

[john e. holliday]

Still didn't say how much it weighed.  I have over 3 ounces of lead on the P-39.  The lead was put on when I had the heavy weight OS 40FP or FS, will have to look at it if I can still find it.  It was three ounces heavier than the OS LA .46 that is in it now.  Had to put extension on the LA.  But, at VSC it weighed in at 62 ounces.

[Paul Wood]

Hey Paul,

I feel your pain!  I was getting ready to glue the tail feathers on my new Profile Oriental when I took a look at the assembled plane.  It was very apparent that the nose was way too long compared to the tail moment.  I weighed the engine/muffler (TT .42) and it was 4 oz. heavier than the Fox .35.  I did a few calculations and ended up adding 7 inches to the aft fuselage.  After paint, it came out exactly on the C.G.  But, it sure doesn't look like an Oriental anymore!  Kinda goofy looking actually.  Been waiting on the winds to lay down a little before I fly it.  It's gonna be plenty stable, but may turn like a tank with that loooong fuselage.  By the way, without the 7 inch extension, I was looking at 7 ozs. in the tail!!

Good luck with your nice looking project,
Paul

[Jerry Leuty]

       It is a pain to get a ship as far along as you have then to discover a major problem such as you have. The logical answer would be to purchase a L&J Fox from Eric Rule along with a tongue muffler and go fly the thing. This is why a lot of Classic ships don't work as well as we remembered them while using the newer engines. Every ounce matters. Years ago I read on Stuka Stunt an article called "Your nose is too long", it may still be on their web site. I also use Max FPs and LAs on all my ships. They are easy to start, very reliable in the overheads towards the end of the pattern and you just cannot wear them out using 29% Castor and 10% nitro. The heavier oil keeps them slowed down a bit on the RPMs but still lots of power to spare. All my 40 size planes have a 9" nose, a 13-14" tail between the trailing edge of the wing and the leading edge of the elevator. I also cut the extension off those big old clunky mufflers and make tongue mufflers out of the extentions. Unless of course I need to move the CG up towards the nose a little then I use the full muffler. Some planes such as the Ringmaster just handle the AMA pattern better with a forward CG. Design your ships using these numbers and you cannot go wrong. Another thing is I use a lot of foam wings and my 52" planes come out around 40 or so ounces with a FP up front. Put on a 11-6 Pro Zinger and go fly the pattern.
        Light winds for your maiden flight on this plane.....................Jerry
         

[Harleyman]

It's looking really good Paul.
Don't fret too much.  Before you hack it all up, test fly it with some extra tail weight first.  With a 46 in the nose, you might be surprised. 

If it flies like a brick, you might want to try moving the engine back to the rear motor mount holes.  Using the current rear motor mounting holes as the new front holes.
Drill new Rear mounting holes and move the firewall (F1) back if needed.  To get new rear blind nuts in, you could slice off a portion of the top block to install them, then re-atttach it.  A little sanding and you'll be good to go.

[Paul Taylor]

I think I am going to try to lighten the load up front as much as I can before I start cutting.

I just put everthing on the scales. I put all the hardware that I still have install on the wing. Canopy, pilot, spinner, clunk tank, t-muffler, and I think it will take ~1.5oz to get it balance on the CG. Total = 50.1oz. Under my target of 52oz.

I still need to find a tail wheel and weight box in the tail.

[Air Ministry .]

Ive been know to shave the fins of the side of the engine , T/R style.

One H.P. 40 head has NONE , but youd need a head gasket , the heat advaces the timing.

good in a cool area . Not in the desert .

Must be dozens of engines with the same footprint . Wots the lightest ? Brodak .40 ?

[Larry Cunningham]

Paul,

Before you cut off the nose, try flying it. You may be very surprised. One of my very best Twisters had a 3/4" longer nose and maneuvered just fine, was a sweet and easy to fly ship. Some of these "Fox .35 with no muffler" designs were a bit skittish compared to modern, slightly larger stunters.

The most nose-heavy model I had was a Roadrunner, with OS .40 FP and muffler. Stock nose moment is very long (it was designed to use a Fox .35 with shaft extension) and it definitely was not maneuverable. Both Mark Bowen and I built these models at the same time, and we had to add a large amount of weight to the tail to get them to maneuver.

At the same time, years later at a VSC a very good flying RR was seen (Mr. Anderson, if I recall?) which was reportedly not using any tail weight.

Plus, some reworked Fox .35s nowadays seem to run more like OS .35 FPs, and there are other lighter motors.

Good luck!

L.

"A man who works with his hands is a laborer; a man who works with his hands and
his brain is a craftsman; but a man who works with his hands and his brain and his
heart is an artist." -Louis Nizer

[john e. holliday]

I think I am going to try to lighten the load up front as much as I can before I start cutting.

I just put everthing on the scales. I put all the hardware that I still have install on the wing. Canopy, pilot, spinner, clunk tank, t-muffler, and I think it will take ~1.5oz to get it balance on the CG. Total = 50.1oz. Under my target of 52oz.

I still need to find a tail wheel and weight box in the tail.

What are you worried about?  With all that you have to do it may come out tail heavy.  I know weight boxes are not light if built out of plywood(5 ply).  Yes over engineered.  In fact one plane I have has no weight in the wing tip because the box is os heavy.  Wait til you get it all together and then fly it if nose heavy.  If tail heavy don't fly til you add some nose weight.