Sky raider I with an OS 46 LA is a little tail heavy and already under powered...Instead of adding weight up front how much impact would removing the two long screws that hold the tail on and glueing the tail have? I know it's not much weight but it is way out on the tail.... ( plus I have the tail apart as I just rammed the doorway with the tail bringing it into the house@&$!*#. Minor repair )


I'm also moving the battery out from under the fuel tank and putting it under the engine. ( haven't figured out how to hold it there yet) By doing this I am able to remove 2.5oz of lead from the nose.

I'll also test 11x5 , 11x6 , 11x7 props this Saturday to see the effects..

How much impact is 2.5 oz going to make? (I,ll find out Saturday )

I had an OS 50sx in this bird but moved it to another plane.
)
Big difference between that and the LA.46

Steve

If it's under powered, then replace the engine with that larger OS 50. That will certainly move that CG forward. Removing the screws is a possibility, but make sure you glue in the tail feathers so that they are nice and square with the fuselage and in alignment with the wing.

CGr.

Steve If you're using epoxy to glue the tail (which I recommend) I don't think you'll see much, if any, weight savings. But do let us know.

Shoot man this thing needs functional working weight up front.Put a saito 82 or a cheaper thunder tigre fourstroke thingy in it..man you'll have a smile from here to there on your dial,cheers

All very ingenuous solutions, John!

No harm in re-checking lateral balance after relocating battery like that, Popriv.

Nice work John B.

Looking at the World Models Skyraider 1 with cowl cheeks, only (apparent)way to mount the battery in front of the firewall would be to zip-tie it to the outside of one of the cowl cheeks.

How about an APCprop? A Zinger 11x7 weighs .7 oz. while an APCweighs 1.5 oz. How about a hub rather than a spinner. Higley hubs weigh either 1 or 2.5 oz. Adding a backing nut (not needed on a 2-stroke) adds another .5 oz.

Bolt on some lead to the FW.

Since this is a trainer you are probably setting the CGat the "nose heavy"recommended location. As your skills improve you may want to move the weight back. Moving a permanently mounted battery "up front"isn't easy to do. Changing props to a wood prop - no brainer. Swapping a heavy hub back to a spinner - no brainer. Unbolt lead from the FW - no brainer.

Btw, the OS46 LAweighs in at 12 oz. while the OS46 AX (or FX) weighs in at 17 oz and the 55 AXat 18.5 oz. Pretty expensive way of adding weight if you don't want the power. If the power of the LAlimits your flying ability, that's different.

Arule of thumb - to counter balance an ounce of weight at the tail (of most 40/60 size planes) requires 4 oz at the firewall.

+1 That's what I'd do.


Pete

I just pulled the 50 out to put in a new profile 3D plane. I just want to try and keep this skyraider flying with what engines I have laying around..

My only options, other than the LA .46 are a thunder tiger pro .36 and an evolution .60 ( which is to big )

I wonder if the newer Pro. 36 would have more power than the older LA .46 ???? Now that would be an option....

Steve

Thanks for the pics John, Thats what I'm thinking for the battery, just have to make it fit the space available...

I may mix a little epoxy and compare the weight to the weight of the screws that are holding the tail in. I realize it wont be much different but the fact its way out on the tail is an unknown factor. ( to me anyway) . Or I'll pull my vanessa balancing scale out and balance without the screws then just place the screws on the tail and see how much they affect the balance.. may be splitting hairs here but I think performance is almost acceptable, just looking for a little more... Alll part of the fun!!!


Steve

Not in the Budget Old fart...

I'm moving on to a new profile Su-do- kio 3-d plane and the 50 has to go in that, I'm just trying to keep this thing flying as best it can with what I've got....

steve

I was going to refer you to John, he posted photos a while back of his battery mounts and they are slick. I'm sure someone will correct me if I'm wrong but as I recall the difference between tail weight and nose weight is about 3 to 1. Takes about 3 times the nose weight to 1 of the tail. The planes I really like and enjoy building all had round engines so before I ever start using the glue I know this ahead of time and try to lighten up the aft section during the build. Can't do this with an ARF but you can get the CG closer with gear placement. It's not a cure all but it helps to lessen the amount of weight needed in the nose. When I assemble an ARF for someone I make up a battery box like Johns. It really helps out a lot.

Yes, I chipped 2.5oz of dead lead weight out of the engine compartment last night and will move the battery there... That will give the most bang for the buck, I was just looking at any ways to also cut tail weight a bit....

Great to see johns pics for Ideas....

If the 3 to 1 is correct, If I remove 3 grams from the tail I can then remove 9 grams from the nose for a total 12 grams less overall weight... ( assuming I have dead weight up front that is)

( I dont have enought experience to know if 12 grams is much help - lol )

thanks all

steve

I may be reading it wrong but it takes a bunch more nose weight to counteract the tail weight, about three times. I just went through this with my last Sukhoi build. Even with three batteries up front I still had to cast a custom lead weight and install it into the nose ring.

A healthy LA .46 propped correctly should be capable of flying a WM Skyraider with authority unless you got unlucky and have one that's made out of iron wood (which happens on occasion with ARF's). A clapped out LA .46 might be marginal.

You can also consider a heavy prop hub which puts weight as far forward as possible.  Don't take any structural screws out of your tail. 

The sky raiders weight is right at the manuals 5lbs. ( a touch under )
I bought the LA .46 used on a Cherokee plane. Not sure of it's condition other than it runs nice but seems to spit fuel more than my other engines ?

The 2 long screws holding the tail together weigh 6.11 grams total, the epoxy I would use to glue the tail weighs about 1.5 to 2 grams.
This would cut 4 -5 grams from the tail. To keep the current CG I would then have to remove " 3 times " that weight from the nose.
That would remove roughly 2oz overall weight (minimum) from the plane.
For now I,m going to keep the screws, save the most weight by moving the battery into the engine compartment, play with props and see how it flys. I will then add 2 - 3 oz weight over the CG just to see what impact that much weight makes. If I CAN feel the affect of that amount of weight I will consider removing the tail screws and epoxying the tail.....

Thanks for all the input...

Steve

OK Steve Yes I must confess in your first post with all the talk of a Skyraider Mach 1 indeed my mind saw Skyraider A1 and of course that scale airplane has a short nose moment and a hugh hole up front, a type that is ideal for mounting the battery up front and the types to benefit the most.

However one of the sets of pictures I posted was not of that type it is infact a Kadet Senior trainer that I use for almost all the primary training. Anyway lets get back to your airplane, I did search on it and it appears to me to be pretty much a genaric forty sized trainer. Please correct me if I am wrong.

If you are carrrying a lot of nose wait and simply getting rid of a bolted tail set that will allow you to get rid of a little of that nose wait then by all means go ahead and glue that puppy. Bolted tail assemblys on a simple trainer type of that size is nothing more than a sales pitch to sell more, its all about how fast they can be assembled, read Gimmick. Glue it.

Now if using a forward battery mount in front of the firewall will help things also and you,ve a mind to do it i. e. the motivation then by all means do it.

OK lets get to that engine. I actually do own one LA 46, its not an engine I would ordinarilly spend time on. However in a buyout I made couple years ago their was a plastic ARF seaplane called a Ready Two. Now this thing had a thourghly clapped out LA 46 on it, Heck that engine looked like it had been whooped with an ugly stick. I thought I would drag it along on my next trip down to Havasu for some water sport after I replaced the completely unrealistic prop it had on it with a APC 11x4 . Well that airplane using that clapped out LA rattle trap made that airplane perform just dandy.

It impressed me enough that I made a takeoff dolly and have flown it off our home field many times and just landed it in the gravel.

Now using a long flat prop like that does not increase your top speed at all, actually it reduces your top speed but it shortens takeoffs and rates of climb at lower speeds and this often is what folks perceive as a faster airplane.

Many older engines similar to the LA and the LA's tend to rattle at idle as the main bering wears and heck as long as they run fine they get even better and sound for all the world just like a teakettle. I use to love my little K&B .20 and .28 Teakettles.

Sorry for the various digressions but by all means fix her up iffin ya feel like it.

John

You are right on the money John, 40 size cheapo trainer I just want to keep flying while I move onto the profile 3D I just set up....

I just want the best I can get out of it using this .40 LA

I will answer my question of how much effect 2 - 3 oz additional weight has on the plane by just sticking weight over the CG and seeing how it effects performance... Just got to try it....

Can the worn parts on the LA be replaced? what parts would they be? It might be a good project to break me in on engine repair?


steve

I used the LA .46 exclusively to compete in fun fly events with my 40 Up-Roars. They are a lot of bang for the buck. Easy to operate and last for a lot of years. I have never worn out a .46 but the .40 was another story. I found them a useless engine but when someone gives me an old trainer there is usually a .40 hanging on the end. They do fly the plane but there is no OS factor in them at all. When they are worn out they spit out a lot of gray in the oil slime and start to rattle a lot.
On the positive side they keep running. I keep using them until there is enough metal floating around in them that they start to burn out the glow plug. Rebuild/repair, nope, they are just a toss and forget engine.
As john mentioned, the prop selection is a great help. I ended up using the APC 11X6 in the Up-Roar planes, the 11X4 in a trainer. There are better engines on the market but the LA .46 is a pretty good engine for the money. Bushing engines do like Castor oil but all I ever used in them was Power Master 15% nitro with 18% blended oil.