CoG advice please - chipmunk

[richard armstrong]

hi all

need some advice before i make a change?

at present i have lead on the tail wheel and 25 grams under the rudder i want to remove the lead weight and replace it with a 4s 3000mah dead battery, just behind the wing on the existing battery plate, i know move the weight forward will have an effect, on CoG,

i wondering if shift the weight forward but increase the battery to compensate would be enough?

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[Cary Bailey]

Richard, you want to add approximately 320grams of weight just behind the wing but effectively only removing 25g plus whatever weight you have on the tail? By my guessing you want to add somewhere in the region of say 200g actual weight onto the model? Why add weight when we all strive to keep the model as light as we can? I propose you either try and lose some weight at the front of the model, remember it is probably a rule of thumb ratio of about 4 to 1, so removing 100 grams of weight at the front will enable you to remove about 25g from the tailwheel! Can you remove some weight from the front?
And putting a "dead" battery into an aircraft just to add some weight to keep the CofG correct is probably not a good idea for the reason that the material that a Lipo is made of, can under certain conditions, ie a crash or even heavy landing, can damage the battery and potentially damage the plane. Why add a risk to your model by adding a battery that you have no intention to use?
Cary

[richard armstrong]

use of a battery is an option but can be replaced with lead block instead of battery,

originally this had 3 heavy nimh's packs in the one behind the wing was for lighting and a 6v c pack

no lead in nose the engine is a fuji 32cc, and is a brick makes very nose heavy without lead in tail

dilemma???????

or do i just leave it alone

[Cary Bailey]

Rich, if it flies OK then leave it alone & try to hide the lead in the tail somehow. If you can reduce some weight from the nose then even better to enable removing some from the tail!
Cary

[richard armstrong]

leaveing it alone for, now

need to think of a way of make a block for the tail with out doing damage to the formers

access hatch??????

[richard armstrong]

has anyone got a COG stand i could borrow at Elvington?

[Cary Bailey]

Rich, make your own!! Give me a call & I will tell you what to do!!
Cary

[richard armstrong]

Rich, make your own!! Give me a call & I will tell you what to do!!
Cary

call you later

i have a design i just found basic but works


ric

[chris-berry]

Richard, Steve flew it for you at Catton after I chickened out and it flew well.

It flew well with little need to change anything, so leave it alone. If it flies, then let it fly and don't mess with things and make sure the lead is secure and cannot ever come off. If you've got a dead battery then either keep it for sizing in other models, or to use as a weight when gluing or just throw it away.

Chris

[Cary Bailey]

Rich, I agree with CB!
Cary

[richard armstrong]

Rich, I agree with CB!
Cary

i leaving it alone and sort it in winter

[chris-berry]

Rich, I agree with CB!
Cary

i leaving it alone and sort it in winter

Richard, it doesn't matter what season it is. It doesn't need sorting. Just fly it and only mess with it if anything changes don't mess with it for the sake of it.

[richard armstrong]

chris, point taken

[Jack Kennedy]

Richard, is'nt that the same plane Steve flew for you at East Kirkby at the start of the year, if so, I was standing next to steve with Mike,and the plane flew great, ( thats down to the pilot ).
I would agree with the rest of the guys, as we say in my neck of the woods, ( if it's not broke don't fix it. )
needless to say, the guys who have given you very good advice, are in my opinion, talking to a brick wall

(You will mess with it )

[richard armstrong]

I HAVE TAKEN THE ADVICE AND LEFT IT ALONE

THANKS JACK

NOT SURE WHAT'S UP with some of the crowd because its that time in the year to have a go at Richard

enough thanks

[Jack Kennedy]

Richard, if you look at the start of your post, you were asking for advice, the crown, sorry, crowd, you are talking about have probably been doing this a lot longer than you or me, you seem to be taking things to personal.

Take the advice and move on