Chad Veich

My Feedback: (60)

This can't be a serious reply. Right?

TimBle

I always balance gear up.

jzak3

My Feedback: (3)

I have a h9 60 size corsair and the cg is done with the retracts up and the plane upside down
That is the way the cg is done.

Corsair2013

My Feedback: (2)

Do you all agree that if you "normally" balance within manufacturer specifications or per the CG formula that you should have a stable plane? Assuming the plane was built correctly and control surfaces are normal.

By "stable plane" I mean a plane that will take off, fly, and land without serious issues.

LesUyeda

"within manufacturer specifications"

Too broad a statement. I have seen the printed "manufacturers specification" to be in error. One must judge for themselves, or rely on the advice/experience of others.

Les

OldScaleGuy

My Feedback: (2)

This is absolutely right on the mark!

Manufacturers specs should be correct but it never hurts to use some common sense and experience for confirmation.

suburban95

My Feedback: (9)

I am not in any way saying anyone is wrong here I am just concerned because I have a Top Flite Sea Fury that I haven't flown yet and according to the manual it says:

� 2. With the wing attached to the fuselage, the
landing gear extended (if retracts are installed), all
parts of the model installed (ready to fly) and an
empty fuel tank, place the model upside-down on a
Great Planes CG Machine, or lift it upside-down at
the balance point marked on the top of the wing.

Now I did it this way but what "Old Scale Guy" and others have said about doing it with wheels up makes sense to me so now I am worried and not sure what to do. The Sea Fury retracts are slanted forward so the gear will hang out further in front of the mount location which of course will effect the CG. I sure don't want to maiden this thing if it is too tail heavy with the gear retracted!

Jaybird

I think what people are saying is that retracts that move from the leading edge to the trailing edge (P-40, F-4U ect) will have a more significant change to the CG as the gear and wheels move from front to back than if they retract from outside to inside (T-6, P-51, P-47 etc). It depends on what the retracts do as to their impact on moving the balance point with respect to the allowable CG range.

Jaybird

jmpups

My Feedback: (1)

It depends on the plane. Many planes where the wheels are in the same position from the leading edge whether the gear is up or down, then it doesn't matter because the CG doesn't change. But when you have a plane where the retract is out by the leading edge and the wheels rotate up towards the center of the wing like a "Skyraider" you need to be checking the CG with the gear up and the weight of the tires further back. The same holds true for a tricycle gear, the weight of the gear is further back in the retracted gear and that is where you need to check the CG. JMPUPS

OldScaleGuy

My Feedback: (2)

Your Sea Fury CG will probably not change dramatically with the gear down or up. However, i would still make sure you have the CG set correctly with the gear up for the first flight. You can always make changes to a plane that you still have...

a65l

My Feedback: (17)

I've owned and flown 1 or 2 airplanes over the years, and if they had retractable gear I always balanced with the gear up, and aimed to be either right at the middle of the CG range, or in the foward half of the range. I have never experienced a problem with a bird going to an extreme of the range when the gear cycled. This included a large EDF with three rear retracting gear, all with very heavy wheels on them.

And IMHO, you want to balance gear up, because there is always the possibility of a gear up landing, and you don't want to get low and slow gear up and discover you're in the unmanegable part of the CG range...

lstimey

My Feedback: (16)

IMO ...Wheels down !! I agree with Chad. You can fly a tail heavy plane with power and some skill. But with out power and zero fuel you need a balanced aircraft with wheels down for landing. Most planes fly nose heavy because of fuel tanks being ahead of the CG point. So balancing for flight is not accurate anyhow.

spadsriver09

My Feedback: (1)

My vote is gear up think if you ever have air leak/electric problem with your gear and you have to belly land. Or go with MFG recommendation.

Me410

As mentioned previous, a Corsair with retracts folding straight back. Now add to that giant scale and maybe if you can afford them, Glennis wheels, beautifull but very heavy. You now have a situation where you could have a pound's worth of wheels and tires. And when retracted they move back, say, roughly five inches. So with a pound of wieght moveing back and forth like that, what do you do with CoG?

My guess would be balance with the gear up and use the rearmost point in the CoG range, because when you lower the gear you will move towards nose heavy.

If you balance with gear down in this case you risk being tail heavy with gear up.

Or spend some time checking and measuring where you are in both positions.

fly24-7

Seems the best answer has already been hit on. You want your plane to be able to fly stable in all configurations. Therefore, it make sense to evaluate your CG with the gear up and down. You should be aware of the balance behavior in both conditions. From my experience, it's never a good idea to have a tail heavy airplane at flying speeds, landing speeds or anywhere in between. With a tail heavy plane, you're always fighting the plane wanting to pitch to an angle of attack that can result in a stall. Since most models are not powered like 3D aerobats, the propellor alone cannot generate enough thrust to keep the plane flying in such a high alpha attitude. In the end, find a balance point that insures the worst case still errors to the side of nose heavy over tail heavy.

FWIW, It typically doesn't make sense to balance a tank with full fuel as the tank typically sits on or ahead of the balance point. So, the worst case is with an empty tank.

SCALECRAFT

My Feedback: (13)

Assuming you don't have heavy wheels and tires. If you do, might want to put in a mix.

On gear that rotate back, I retract my gear and balance my model inverted, dry. Makes for an easy balance.

Our composite Scalecraft Corsair (54" span) has been balanced like that for years and has always come home safely. Of all our composite models, the Corsair was the most forgiving at slow flight.

If your CG is off, better to be on the nose heavy side. A properly CD'ed model will land far easier than a light non CG'ed model.

Steve

lstimey

My Feedback: (16)

Page 64 in the manual. Gear down !!

CRG

My Feedback: (3)

Gear up or down is case by case, there's no blanket rule. Verify that the aft CG limit is not exceeded in whichever configuration places the CG most aft. In the case of the Corsair, this is gear up and no fuel. With full fuel and gear the down the CG will move forward, this is normal.

In the case of the Hangar 9 Corsair 50 it is recommended by Horizon Hobby that it be balanced gear up.

Craig

Bozarth

My Feedback: (15)

Google "stretch a glide" and then decide if it really is a good idea or not.

Kurt

on_your_six

My Feedback: (11)

You don't want it tail heavy in either gear up or gear down configuration. Check both, balance for worse case situation.

RCFlyerDan

My Feedback: (54)

IHMO, with a tail dragger, it doesn't matter. The only time it matters is on a tricycle gear, due to retracted, the nose gear shifts the wt to a more tail heavy situation.

CRG

My Feedback: (3)

It can matter a great deal with a taildragger, especially if the gear retracts aft (Corsair, Hellcat, Warhawk etc.). It rarely matters much on a tricycle-geared model as the nose gear remains forward of the CG whether up or down.

RCFlyerDan

My Feedback: (54)

I forgot about those warbirds, and knew I was going to get caught on that statement, so, yes, I agree on those war birds that swing the gear forward or aft, balance gear up, or at the point of the most extreme. On my tricycle turbine jets, it DOES MATTER for the balance! I fly them on the rear edges of my CG, so retracting the gear can still go to the tail heavy postion in flight with fuel burn from 4 tanks on my F-18. The Flash and Viper aren't as critical, but since I fly 3D with them on some manuevers, ex: an inverted flat spin, blenders, etc. I have those two jets balanced on the aft part of the CG, or maybe even behind. The CG is only the beginning balance point from the manufacture, then I continue to balance in the air after several flights, and reading the "signs" of the plane/jet talking to me.

jeffEE

My Feedback: (5)

Gear up for CG on Corsair with retracts.

Bozarth

My Feedback: (15)

"behind" what?

Kurt