hyflyer9

Hello all
i have an ESM Frank Tiano edition P47 and I am having a little bit of a problem to get it balanced properly. I am doing my balancing on a great planes CG Machine with the Gear up and I can get to balance level by adding a very small amount of weight but when I drop the main gear it noses over a lot I would say at around 70% nose heavy. It just doesn't seem rite that it would be that nose heavy with the gear down .
Help Please .
hyflyer9.

Warbird Man

My Feedback: (95)

Balance the plane inverted with gear retracted. Then your good to go. Don't worry about what happens with gear down.

Johnnie Red

Hey hyflyer9

First of all do you ballance the bird upsidedown? The low wing planes are ballanced upsidedown.
If you ballance it with gear up then its o.k. if it gets nose heavy with gear down since this bird has flaps that you definately will use in order to land.

Keep in mind that you 'll have to ballance this bird on the 1/4 of the chord of the airfoil at the saddle. That means at the 25% of the chord which is nose heavy in comparison with other lets say 3D sport planes.

I fly the same bird with a 180 FS and it is rock solid.

Happy flyin'
J.R.

spaceworm

I really don't know , but some planes are specified to be balanced inverted rather than upright. If you haven't yet, you might check the manual to see how they suggest it be balanced. On the other hand I also don't know if balancing it inverted makes any difference with regards the gear retracted. Maybe just disregard this reply and wait for someone who really knows.

Sincerely, Richard

Johnnie Red

Dear Richard

All lowwing planes are ballanced inverted. Only highwing trainers and middle wing (with diahedral) are ballanced upright.

Happy flyin'
J.R.

hyflyer9

Yes guys I do balance my war birds inverted so with the plane level with my gear up inside the wing is good .

Johnnie Red

Then go for it. Don't worry about anything. What setup are you using? (engine etc.) and how much it weights ready to go?

MinnFlyer

My Feedback: (4)

Why balance upside down? Read this to find out:

[link=http://www.rcuniverse.com/magazine/article_display.cfm?article_id=601]Balancing Upside Down[/link]

Lnewqban

When the gear is out, the CG moves up to above the support points of the CG machine.

The configuration becomes unstable like a pendulum that is upside down.

In that condition, it is impossible to balance the plane, and the whole purpose of balancing it upside down is defeated.
The plane just pitches or drops towards either the nose or the tail, while the CG tries to find a more stable lower point.

If you balance the plane right side up with the gear extended, the CG location should be about the same that you have marked in the upside down position (except if the gear mechanism moves the CG of the gear forward a lot when extended).

In any event, the balance should be done in whatever flying condition for which the CG is as aft as possible.
If the CG is to move in flight, it must do it only forward of the recommended balance point.

Johnnie Red

....

This is my ESM P-47D with at least 100 hours on the clock!

hyflyer9

Ok here it is the set up is 8 All hightec 5625mg high torque metal gear servos and Hitec Optic TX 2.4 with a hitec optima 7 RX /EMS scale air retracts with a Robart speed adjust control valve and an RCGF 26cc Gas engine spinning an Xoar 18x8 silver prop and 1 2300 mah 4.8 NI-MH for the ignition and 2 1100 mah 6.6V A123 for the RX and all on separate switches for redundancy . And it only takes about three ounces of added weight on the nose to balance it . and the weight ready to fly is about 15lbs

Johnnie Red

Very nice set up, welldone. The bird will fly fantastic. The only thing that you have to take good care is in landings to be as gentle as possible with the stock retracts. (they do not hold on in bouncy touch downs).

hyflyer9

Here is a nice photo of My p47 and my top flight P39 from last summer

Johnnie Red

Wow that is a nice photo of two beauties!!

The P-39 reminds me a Top Flite one that I have unfortunately sold last year. (I changed my mind and I still miss this bird, it was a nice flyer).

Don't worry about anything on the P-47. It flies like in rails. More or less like your Airacobra!

Go for it pal! Keep us posted about how it will be your maiden.

Cheers
J.R.

rctech2k7

My Feedback: (1)

That looks like a heavy landing gear when approx 70% of the weight shifted forward. Check how much torque added or CG displacement might be within safe margin if not too much distance. The small pitch torque added by the change in CG can be compensated by the elevator surface control area, distance, airspeed and elevator trim... It's better to fly an aircraft with slightly nose heavy than slightly tail heavy, just a little extra airspeed or added elevator mix for low speed. In that way you're going to takeoff and land the more stable aircraft than when the gear is retracted...

hyflyer9

When I put the plane on the Cg machine with no weight added it is a little tail heavy but when i extended the gear it drops the nose a lot . And yes i am balancing it inverted . But as Lnewqban said sometimes you can balance a low wing plane like a high wing plane as the main gear will make it top heavy thus changing the CG

I did do about 8 flights with it last summer and had a small miss hap on that 8th flight I got it fixed over the winter but I don't remember it being so nose heavy with the Main gear extended.

rctech2k7

My Feedback: (1)

That post by Lnewqban & MinnFlyer are good illustration how impossible to balance an aircraft when inverted with CG below the wing (on upright position) unless CG is above the wing (on upright position) or at least below the support point when inverted. However, if the CG is above the wing on upright position, the better way is to balance on inverted. Also shown how stability affects the self-righting of an aircraft, there should always be something to counter the moment torque either by gravity or dynamic force…

hyflyer9

I Guess the best way is to go with what I got as my balance inverted with the mains retracted at about 3% nose down thanks to all for your help and I will post on my maiden flight soon .

Lnewqban

I agree.

Best luck with your first flight.

Just for future balancing acts, the Vanessa CG rig is immune to vertical movements of the CG:

http://www.rcuniverse.com/forum/m_70.../tm.htm#708060

It can also be used for lateral balance and a spatial location of the CG.

Dash7ATP

HI guys,

Unless you plan to fly and land upside down,  why fool with a system that is a pain to deal with .  Check out this technique.  It works very well for all types of models. It even allows you to fuel it, check the effects of retracts, etc, all without having to worry about it falling off of the "machine" and causing hanger rash. It's easy to set up, very low cost, the most accurate and sensitive,  safe to use.

Dash

http://www.rcuniverse.com/forum/m_99...tm.htm#9941336