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Newbie Question about plane weight

Old 02-13-2009, 08:37 AM
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bigal126
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Default Newbie Question about plane weight

Ignorant newbie question. I recently finished building my Midstar. I finally got an opportunity to weigh it. When you check the weight of the plane, does that include the weight of the engine? The instruction manual says the plane should weigh 5 lbs. My plane weighs just under 6 lbs with the engine, all ready to fly.

I probably built it heavy, being new to this, but for reference in the future does the 5 lbs. indicated in the manual with our without the engine?
Old 02-13-2009, 08:45 AM
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Deadeye
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Default RE: Newbie Question about plane weight

Typically, the all up weight of a plane is the weight of it ready to fly, without fuel. Most manufactureres err on the light side when they spec out their planes.
Old 02-13-2009, 08:45 AM
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john911
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Default RE: Newbie Question about plane weight

my trainer came in 6.5 pounds with a 40 on it it flyes great
Old 02-13-2009, 08:45 AM
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RCKen
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Default RE: Newbie Question about plane weight

What Deadeye said.

Ken
Old 02-13-2009, 09:15 AM
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bigal126
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Default RE: Newbie Question about plane weight

Okay. Now I was told by an experience flyer to move the center of gravity up 1/4" from where it is now. He said that it's best to have it more forward than aft for a new plane. Does that sound right? The battery is all the way forward now. So he said to add weight up front. What's the best way to do that? What do you use for weights?
Old 02-13-2009, 09:21 AM
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Deadeye
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Default RE: Newbie Question about plane weight

You are better off more nose heavy than tail heavy, especially on a maiden. Get a feel for the plane first, then you can slide your CG fore or aft to fine tune it. As long as you balance within range of what the manual says (probably dead nuts on the center spar), you should be OK.
Old 02-13-2009, 09:23 AM
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Default RE: Newbie Question about plane weight

The stick on lead weights are probably the easiest way to add weight to the nose. You may also want to see if you can move your engine forward on the engine mount by a small amount. It is a little bit of work, but it might save you from adding weight.

Good luck
Old 02-13-2009, 09:25 AM
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Default RE: Newbie Question about plane weight

Are you planning on using the Mid-Star as a trainer? It's probably possible if you have a willing instructor and you are a quick learner. It's typically more of a second, or even third plane.

Good luck
Old 02-13-2009, 09:55 AM
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bigal126
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Default RE: Newbie Question about plane weight

Presently, the CG is just aft of the center spar. He said to move it like you said Deadeye onto the spar.
Okay sticky lead wieghts. I know where I can put them and where to get them. Thanks.
At this point, I know someone who is an experienced flyer. He's gonna fly it. I may or may not try. I just had fun building. Right now I'm focusing on making sure everything is set up properly so when the weather turns, my friend can let it rip.
Next step will be breaking in the engine. There's lots of information in the forum on that one.
Thanks for all the help.
Old 02-13-2009, 10:07 AM
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Default RE: Newbie Question about plane weight

As a further suggestion: the further forward or further back you add the balance weight the less need. On an already heavy model it is best to do as much by moving the battery, also.
Old 02-13-2009, 10:18 AM
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Default RE: Newbie Question about plane weight

On a further note from Charlie P's... you can get stick on lead weights that are circular and fit inside the prop spinner, around the prop nut. That's about as far forward as you can get, hence the least weight added. As a bonus they'll act as a flywheel giving you a smoother idle, but they will slow the throttle response. They also need to be well centred around the prop shaft or they'll be out of balance.

Oh and the cheapest place to get stick on lead weights is a car tyre place... they're the same weights as the hobby shops sell for four times as much, and often the tyre places will just look at you a bit funny and give you a couple of strips for free.

If you check your plane's manual it should tell you where the plane should be balanced... so many inches back from a certain part of the wing. For a maiden start with the furthest forward portion of the manufacturer's recommended balance point.
Old 02-13-2009, 11:09 AM
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Default RE: Newbie Question about plane weight


ORIGINAL: Sandmann_AU

On a further note from Charlie P's... you can get stick on lead weights that are circular and fit inside the prop spinner, around the prop nut. That's about as far forward as you can get, hence the least weight added. As a bonus they'll act as a flywheel giving you a smoother idle, but they will slow the throttle response. They also need to be well centred around the prop shaft or they'll be out of balance.

Oh and the cheapest place to get stick on lead weights is a car tyre place... they're the same weights as the hobby shops sell for four times as much, and often the tyre places will just look at you a bit funny and give you a couple of strips for free.

If you check your plane's manual it should tell you where the plane should be balanced... so many inches back from a certain part of the wing. For a maiden start with the furthest forward portion of the manufacturer's recommended balance point.

I always wondered about weight be adding around teh spinner and prop nut. Does it have any adverse effects, such as wear and tear on the crankshaft or bearings?

Thanks,
BH
Old 02-13-2009, 11:26 AM
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Sandmann_AU
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Default RE: Newbie Question about plane weight

If it's off centre it'll increase bearing wear, vibration etc... same as an unbalanced spinner or prop will. If it's balanced it's the same as running a heavy prop - flywheel effect.
Old 02-13-2009, 11:28 AM
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Villa
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Default RE: Newbie Question about plane weight

I do NOT trust a lead Stick-On for more than a test flight. They will fall off and can hurt someone. If I decide to keep the lead weight after a test flight, I tie them in place in one manner or another. Don't think of the lead as something that will not cost you much if it falls off. Think of it as something that will fall off and put someones eye out.
Old 02-13-2009, 11:33 AM
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jib
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Default RE: Newbie Question about plane weight

When I used lead weights, and I don't anymore, I'd put a screw through the cowl, into the weight, to keep it in place. If you don't, the fuel will eventually dissolve the glue and release the weight.

Thanks for the reminder Villa.

Jack

Edit - I have a 6.5 pound trainer (SPAD Debonair), powered by a TT GP-42 and it's a joy to fly.
Old 02-13-2009, 11:36 AM
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Default RE: Newbie Question about plane weight

Zip ties work well too, if you're putting them somewhere like an engine mount. They also absorb some of the engine's vibration there - same as handlebar end weights do on a motorcycle.
Old 02-13-2009, 01:37 PM
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Default RE: Newbie Question about plane weight

Here are the weights that can be added to spinner:

http://www3.towerhobbies.com/cgi-bin...?&I=LXK245&P=7

They have adapters for different prop shaft diameters. I have used them in the past without problem.

Bruce
Old 02-13-2009, 01:48 PM
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Default RE: Newbie Question about plane weight

They also sell brass spinner nuts that will add weight to the front of the engine.
Old 02-13-2009, 01:54 PM
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Default RE: Newbie Question about plane weight

I have a question about plane weight. What is the best way to weigh it?



john
Old 02-13-2009, 05:21 PM
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Default RE: Newbie Question about plane weight

I have wieghed my Sig 4* two different ways and they agreed with each other. I have a small scale that I put under each wheel and added the values together. I also used a spring scale and held the plane up with it. They were pretty close to each other so I think both methods are pretty accurate. I don't know if this is the best way, but it is the way I did it.
Old 02-13-2009, 06:31 PM
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TedMo
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Default RE: Newbie Question about plane weight

baby scale works very well.
Old 02-13-2009, 06:46 PM
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Default RE: Newbie Question about plane weight


ORIGINAL: Sandmann_AU

If it's off centre it'll increase bearing wear, vibration etc... same as an unbalanced spinner or prop will. If it's balanced it's the same as running a heavy prop - flywheel effect.
I have seen a lot of arguments about this and it can get ugly at times. I have used the weighted nuts over the years without any problems with the bearings and they have worked out well for me. I have never tried the weights mentioned so I haven't a clue about them.
The weight of the plane is another point that has brought up a lot of issing matches. My feeling is that today the ARFs are built too light compared to a kit built plane of the same type. I see a lot of old kit planes still flying and doing it very well, not a lot of old light weight ARFs?
No reason for any replys to that statement, just something I have noticed.
Old 02-13-2009, 06:48 PM
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Default RE: Newbie Question about plane weight


ORIGINAL: BigHog


ORIGINAL: Sandmann_AU

On a further note from Charlie P's... you can get stick on lead weights that are circular and fit inside the prop spinner, around the prop nut. That's about as far forward as you can get, hence the least weight added. As a bonus they'll act as a flywheel giving you a smoother idle, but they will slow the throttle response. They also need to be well centred around the prop shaft or they'll be out of balance.

Oh and the cheapest place to get stick on lead weights is a car tyre place... they're the same weights as the hobby shops sell for four times as much, and often the tyre places will just look at you a bit funny and give you a couple of strips for free.

If you check your plane's manual it should tell you where the plane should be balanced... so many inches back from a certain part of the wing. For a maiden start with the furthest forward portion of the manufacturer's recommended balance point.

I always wondered about weight be adding around teh spinner and prop nut. Does it have any adverse effects, such as wear and tear on the crankshaft or bearings?

Thanks,
BH
Sorry, this was the quote I was answering about crank weights.

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