3 glider questions

[Tmcfarland]

Seeking recommendations on three issues
1. I have built 3 gliders from kits. An Aeronaut 2m res, a Hollien Introduction 3m and an Eli 2m res. All were built according to plans and instructions. Covered with Aloft transparent covering. Trying to build light I was happy on all 3 to see that they matched the specified weight or a bit under. Then I do the weight and balance and am disappointed to find I will need to add a significant amount of nose weight. Often tough in narrow gliders. In talkng to others at the flying field I hear this is common. Any thoughts? I like to build floaters and hate to add more weight.
2. Seeking recommendations for the best connectors for automatic spoiler servo connections at the wing root / fuselage junction.
3. I see people using rubber bands on folding props to fully close them when the motor is off. Wondering if that is a special band or size? I have a 30mm spinner.
Thanks for any advice or insight.

 

[Doc James Hammond]

Seeking recommendations on three issues
1. I have built 3 gliders from kits. An Aeronaut 2m res, a Hollien Introduction 3m and an Eli 2m res. All were built according to plans and instructions. Covered with Aloft transparent covering. Trying to build light I was happy on all 3 to see that they matched the specified weight or a bit under. Then I do the weight and balance and am disappointed to find I will need to add a significant amount of nose weight. Often tough in narrow gliders. In talkng to others at the flying field I hear this is common. Any thoughts? I like to build floaters and hate to add more weight.
2. Seeking recommendations for the best connectors for automatic spoiler servo connections at the wing root / fuselage junction.
3. I see people using rubber bands on folding props to fully close them when the motor is off. Wondering if that is a special band or size? I have a 30mm spinner.
Thanks for any advice or insight.

1. Make the nose a bit longer.
2. MPX green connectors - more or less standard for this job.
3. Sorry - can't help you with that one.

Doc.

 

[Tmcfarland]

1. Make the nose a bit longer.
2. MPX green connectors - more or less standard for this job.
3. Sorry - can't help you with that one.

Doc.

Thank you Doc. Just frustrating to buy an expensive kit, build it to specs, use the specified motor and still have to add a lot of weight. I wonder if the kit manufacturers know they are selling tail heavy gliders.

 

[Doc James Hammond]

Thank you Doc. Just frustrating to buy an expensive kit, build it to specs, use the specified motor and still have to add a lot of weight. I wonder if the kit manufacturers know they are selling tail heavy gliders.

I think it could be that the kit manufacturers are not fully able to contain their balsa quality, Tim.

Good stuff is hard to find.

Doc.

 

[Wayne]

It is rare to find a model that requires tail weight to make CG. This would be the better option as you can use much less wait to make CG thanks to the longer tail length. But why is this? Here are some thoughts on this:

• Cosmetics - We are all used to a certain look on our models, so when a designer works on a design, he tends to want to make the nose shorter by default.
• Aerodynamics - A longer nose does come at a cost to stability, a longer nose can require a little more tail area to keep tracking where we expect it, with this said, most models tend to have massive tail areas by default.
• Electrics - If the model may carry an electric motor in the nose, this plays a primary role in nose length. The designer needs reach CG with a wide range of battery and motor combinations. None of this is great for a pure glider.
• How light? - Most gliders work well with the small amounts of weight being added to make CG. Does it even hurt performance? While a very light model is a good goal, reality is a super light model will not be fun to fly in anything less than SMOOTH air.

I'm sure there are others issues that contribute, but this is very common, and it is not at all limited to wood models. Many composite models can require a LOT of weight to make CG. But these models are typically slope, and slope pilots hardly think twice about weight. We are usually trying to figure out how to get them heavier.

I'm working on a new design right now. It can be a pure glider or an electric. In pure glider mode the nose is about 1" longer and will have a cavity in the balsa nose for any needed ballast, thus reducing the amount of total ballast needed. In other design I have moved the servos forward or rearward between the glider and electric versions to help with CG. It is a small amount of weight, but it can help.

 

[Tmcfarland]

Great info. Thanks Wayne. Its funny I see Youtubes of meticulous builders weighing control horns and using 1mm carbon pushrods. Then theres me shopping for lead to make it work

 

[Wayne]

Great info. Thanks Wayne. Its funny I see Youtubes of meticulous builders weighing control horns and using 1mm carbon pushrods. Then theres me shopping for lead to make it work

Yes, thermal pilots will sometimes get a bit out of control on weight control. For a while it was fashionable to brag about how light your DLG was, but after many durability issues with the ultralights, the trend reversed and people stopped pushing the manufacturers for ultralights. The mid weights flew better and in more conditions. An ultralight can have it's uses, but not for a sport pilot IMHO.

Anyhow, I was just trying to point out why this tends to be a common issue.

 

[Asat]

Tmac - the rubber bands to hold the props closed are of many kinds - some use an o ring (about 25mm diameter or so) and some use ladies pony tail bands that come in a bag of 100 or so at wal mart etc or you can use horse mane braiding rubber bands available online or at CAL ranch or Tractor Supply stores

 

[Wayne]

I have seen the elastic from a guys underwear used! We call that a field fix.

In general I don't worry too much about it.

P.S. Reading the post above, I think he was answering what bands people use to keep the blades closed during transport, not for in flight.