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-   -   Balsa kit building (http://www.Wattflyer.com/forums/showthread.php?t=72902)

thepiper92 01-01-2014 10:54 PM

Balsa kit building
 
I just ordered a balsa kit, a Mountain Models P 51: http://www.mountainmodels.com/produc...roducts_id=201

I will not doubt be throwing on a 2 blader, rather than a scale 4 blader, but I am excited nonetheless. I have a few questions about building though, as I have never built anything balsa before. For the main build, would it be wise to add in carbon fiber, and where? Secondlyh, how does one bend balsa? Thirdly, for the motor, it is meant for a gear box, would it take much it throw in an outrunner, most likely a 2836 size? Also, where do I use thick CA and where do I use thin CA? Lastly, how exactly do I wrap the plane? I understand it is a covering that is heated up and shrinks, but is there a certain way to cut the covering and a certain tool to heat it with? It wont be for some time before I get the plane, but I would like some insight from those who have built planes before, or links to sites that give good directions on the procedures required.

gramps2161 01-01-2014 11:15 PM

piper excellent build thread on this plane here is a link should have all your questions answered with a little reading.
http://www.wattflyer.com/forums/showthread.php?t=45032

Another build thread here .

http://www.wattflyer.com/forums/showthread.php?t=55367

tobydogs 01-01-2014 11:21 PM

piper,nice build! do a build thread here at wattflyer and we'll follow along as ya go.

some of your questions on covering have me suggesting you p/u a cheap balsa build like the micro telemaster and practice covering it as it's a flat surface fuse. and the wing will get you hands and skills on covering ready to make the p51 look really good.

http://www.hobbyexpress.com/images_t...elated_top.jpg
Micro-Telemaster Kit V2

http://www.hobbyexpress.com/images_p...7165_small.jpg
Product# TEL1100
http://www.hobbyexpress.com/images_t...einfobrief.jpg
Price: $49.99

fhhuber 01-01-2014 11:25 PM

I have a preference to use yellow wood glue (Aliphatic resin) for most of my building with balsa.
Cheaper than CA
Not as brittle
Doesn't harden the balsa creating stress points.
More working time and you can heat the joint to take it apart if its not right.
Makes up for small gaps better than even thick CA.

gramps2161 01-01-2014 11:29 PM

Quote:

Originally Posted by fhhuber (Post 935912)
I have a preference to use yellow wood glue (Aliphatic resin) for most of my building with balsa.
Cheaper than CA
Not as brittle
Doesn't harden the balsa creating stress points.
More working time and you can heat the joint to take it apart if its not right.
Makes up for small gaps better than even thick CA.

Couldn't agree more on the good old yellow wood glue for building Titebond II is my go to glue now.

thepiper92 01-01-2014 11:38 PM

Quote:

Originally Posted by gramps2161 (Post 935913)
Couldn't agree more on the good old yellow wood glue for building Titebond II is my go to glue now.

Why didn't I think of that, I did woodworking for some time in school, was a master at it, should have thought of the wood glue instead of the CA. And I just realized there are directions for the plane. Just looked them over quickly, that will help a lot.

thepiper92 01-02-2014 12:32 AM

What's the best option for heating the solarfilm? I'm seeing heating irons, heating guns.

fhhuber 01-02-2014 12:56 AM

The important part about covering is getting the edges down, pulling the wrinkles out as best you can.

WHat works best for the final shrinking is a heat gun of some sort (hotter than a blow dryer). but you can just use a common travel iron. I did all of my covering work for over 20 years with a travel iron I got for $1 at a garage sale. I still use that for ironing down the edges and often don't bother getting the heat gun out.

What you get used to using will influence your techniques and can make it so you have trouble transitioning to a different tool.... I can't use the specialty covering irons at all.

thepiper92 01-02-2014 01:07 AM

Quote:

Originally Posted by fhhuber (Post 935925)
The important part about covering is getting the edges down, pulling the wrinkles out as best you can.

WHat works best for the final shrinking is a heat gun of some sort (hotter than a blow dryer). but you can just use a common travel iron. I did all of my covering work for over 20 years with a travel iron I got for $1 at a garage sale. I still use that for ironing down the edges and often don't bother getting the heat gun out.

What you get used to using will influence your techniques and can make it so you have trouble transitioning to a different tool.... I can't use the specialty covering irons at all.

I ordered one of the Hangar 9 Irons, a smaller one, hopefully that will work for me...once I get to actually covering the plane that is. Looking at videos, it doesn't seem to difficult, and one set of directions mentions tacking one corner and actually stretching the film a bit to the next corner, thus eliminating most of the shrinking process.

Larry3215 01-02-2014 01:26 AM

Changing over to an outrunner from a geared inrunner is fairly simple. The main thing is you will likely need to build a new firewall more forward than the existing firewall as most outrunners are shorter then most geared inrunners.

The most important thing to have when building a balsa kit is a FLAT building surface. If your build table has warps or twists in it - so will your finished model. I tape the planes to the building table, then cover with wax paper or clear cellophane to keep them from getting covered in glue. Then build right on top of the plan.

Mountain Models kits mostly jig up by themselves, but some of the smaller sized T-pins or some dress making pins (with the bead on the end) will help to pin pieces in place on top of the plans while the glue sets.

Some other good things to have when building a balsa kit - various grades of sandpaper, razor knife or blades, razor saw, hobby plain, small clamps and most any other wood working tools you ay have.

Good luck!!

thepiper92 01-02-2014 01:33 AM

Quote:

Originally Posted by Larry3215 (Post 935930)
Changing over to an outrunner from a geared inrunner is fairly simple. The main thing is you will likely need to build a new firewall more forward than the existing firewall as most outrunners are shorter then most geared inrunners.

The most important thing to have when building a balsa kit is a FLAT building surface. If your build table has warps or twists in it - so will your finished model. I tape the planes to the building table, then cover with wax paper or clear cellophane to keep them from getting covered in glue. Then build right on top of the plan.

Mountain Models kits mostly jig up by themselves, but some of the smaller sized T-pins or some dress making pins (with the bead on the end) will help to pin pieces in place on top of the plans while the glue sets.

Some other good things to have when building a balsa kit - various grades of sandpaper, razor knife or blades, razor saw, hobby plain, small clamps and most any other wood working tools you ay have.

Good luck!!


I found some stick motor mounts. Looking around, apparently that's what other people building the plane used. I have plenty of x-acto blades and a lot of sandpaper. Good idea about the clamps and pins. Pins would definitely come in handy holding things in place.

Larry3215 01-02-2014 02:56 AM

Stick mounts work well for low power setups - under say 150-200 watts. Much over that and they can cause problems - vibration mostly - especially if you use a long stick or one that isnt strong enough.

Keep us posted on progress :)

Larry3215 01-02-2014 03:01 AM

By the way, here is one of the best covering 'How to' threads Ive seen.

http://www.rcgroups.com/forums/showt...=711624&pp=100

thepiper92 01-02-2014 04:53 AM

Quote:

Originally Posted by Larry3215 (Post 935951)
Stick mounts work well for low power setups - under say 150-200 watts. Much over that and they can cause problems - vibration mostly - especially if you use a long stick or one that isnt strong enough.

Keep us posted on progress :)

So stick mounts are no good really. What's my option then?

fhhuber 01-02-2014 05:16 AM

Simply make a box to push the motor forward.... or move the firewall forward.

Most likely if you move the firewall you'd have to put in a bulkhead at the original firewall position and wouldn't gain anything vs the box. The box is another convenient place to put some lead ballast.

thepiper92 01-02-2014 05:47 AM

So even this is no good for higher power?
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXYWY5

Sorry still trying to understand all this. Is the mount the issue or the stick itself in terms of too much power. If that's the case I would have to make something that mounts to the frame itself?

Larry3215 01-02-2014 06:09 AM

Quote:

Originally Posted by thepiper92 (Post 935961)
So stick mounts are no good really. What's my option then?

A lot depends on how long the stick is and the quality of the stick itself as well as how powerful the motor is.

However, the recommended power systems for that model is only capable of 150-175 watts or so at the absolute maximum, so a stick mount will be fine as long as you dont use a balsa stick. Find a nice smooth grained basswood or spruce stick and you will be fine :)

You could easily use a more powerful outrunner if you wanted but as I said, I would not go much above 200-250 watts or so if the stick is more than two to 3 inches long unsuported.

thepiper92 01-02-2014 06:21 AM

Quote:

Originally Posted by Larry3215 (Post 935965)
A lot depends on how long the stick is and the quality of the stick itself as well as how powerful the motor is.

However, the recommended power systems for that model is only capable of 150-175 watts or so at the absolute maximum, so a stick mount will be fine as long as you dont use a balsa stick. Find a nice smooth grained basswood or spruce stick and you will be fine :)

You could easily use a more powerful outrunner if you wanted but as I said, I would not go much above 200-250 watts or so if the stick is more than two to 3 inches long unsuported.

Okay, so I am guess this is overkill? https://www.hobbyking.com/hobbyking/...er_1200kv.html

It is what the Mini Switch is running. Will this plane actually be lighter than a foam one? I'm guessing the plane doesn't come with a stick, or if it does it is likely balsa. Where are some basswood sticks available?

Larry3215 01-02-2014 06:30 AM

Yup - way overkill :) That model will build very light if you're even moderately careful - under 20 ounces if you follow the plan.

So 150 watts works out to 140 watts per pound of model. Thats enough power to do 3D flying :)

A 350 watt power system would be 280 watts per pound of model - which is beyond insane power levels.

The model is designed for 100-150 watt power range. The structure might not handle 350 watts well at all - as in having ther frront of the model depart in flight :)

Id recommend no more than 200 watts or so max :)

kyleservicetech 01-02-2014 06:32 AM

Quote:

Originally Posted by thepiper92 (Post 935906)
I just ordered a balsa kit, a Mountain Models P 51: http://www.mountainmodels.com/produc...roducts_id=201

I will not doubt be throwing on a 2 blader, rather than a scale 4 blader, but I am excited nonetheless. I have a few questions about building though, as I have never built anything balsa before. For the main build, would it be wise to add in carbon fiber, and where? Secondlyh, how does one bend balsa? Thirdly, for the motor, it is meant for a gear box, would it take much it throw in an outrunner, most likely a 2836 size? Also, where do I use thick CA and where do I use thin CA? Lastly, how exactly do I wrap the plane? I understand it is a covering that is heated up and shrinks, but is there a certain way to cut the covering and a certain tool to heat it with? It wont be for some time before I get the plane, but I would like some insight from those who have built planes before, or links to sites that give good directions on the procedures required.

Yeah
Add me to the list of suggesting yellow Titebond glue, rather than CA. It's easier to work with, much easier to sand, and from tests I ran several decades ago, after the Titebond has dried for 24 hours, it's less weight.

And, if you really screw up during the build, just hit the Titebond glue joint with a heat gun, and peal apart the wrong glue joint with a DULL knife. Then, just re-do it.

This also works with epoxy glue joints, but be careful of the fumes.

Don't try this with CA. CA won't let go, and it will stink up the house with who knows what is in the fumes.

thepiper92 01-02-2014 06:33 AM

Quote:

Originally Posted by Larry3215 (Post 935969)
Yup - way overkill :) That model will build very light if you're even moderately careful - under 20 ounces if you follow the plan.

So 150 watts works out to 140 watts per pound of model. Thats enough power to do 3D flying :)

A 350 watt power system would be 280 watts per pound of model - which is beyond insane power levels.

The model is designed for 100-150 watt power range. The structure might not handle 350 watts well at all - as in having ther frront of the model depart in flight :)

Id recommend no more than 200 watts or so max :)

Yikes, it's slightly larger than the Mini Switch and actually lighter. Good thing I have other motors.

Larry3215 01-02-2014 06:35 AM

Quote:

Originally Posted by thepiper92 (Post 935967)
Okay, so I am guess this is overkill? https://www.hobbyking.com/hobbyking/...er_1200kv.html

It is what the Mini Switch is running. Will this plane actually be lighter than a foam one? I'm guessing the plane doesn't come with a stick, or if it does it is likely balsa. Where are some basswood sticks available?

It may be a balsa stick as its only designed for low power setups. I never use balsa sticks though - Ive had too many issues with them. Ive done many many stick mounted motors over the years. Its easy to make your own or you can go to HomeDepot and get a 1/2"x1/2"x36" long pre-cut hardwood stick. You will need to sand it down to 10mm but you can get several sticks for just a couple of bucks. Just check the stick to be sure the grain runs parallel to the long dimension and its nice and straight and you will be fine.

kyleservicetech 01-02-2014 06:41 AM

Quote:

Originally Posted by Larry3215 (Post 935973)
It may be a balsa stick as its only designed for low power setups. I never use balsa sticks though - Ive had too many issues with them. Ive done many many stick mounted motors over the years. Its easy to make your own or you can go to HomeDepot and get a 1/2"x1/2"x36" long pre-cut hardwood stick. You will need to sand it down to 10mm but you can get several sticks for just a couple of bucks. Just check the stick to be sure the grain runs parallel to the long dimension and its nice and straight and you will be fine.


Yeah
Sand it down to fit. For some reason, I've had problems trying to glue some of that square stock. Don't know why, it might be due to some natural oils present in the wood??? For me, sanding it down made it work OK.

That square material is some strong stuff, just try gluing some scraps of it first to make sure all is well.

solentlife 01-02-2014 07:00 AM

Quote:

Originally Posted by Larry3215 (Post 935973)
It may be a balsa stick as its only designed for low power setups. I never use balsa sticks though - Ive had too many issues with them. Ive done many many stick mounted motors over the years. Its easy to make your own or you can go to HomeDepot and get a 1/2"x1/2"x36" long pre-cut hardwood stick. You will need to sand it down to 10mm but you can get several sticks for just a couple of bucks. Just check the stick to be sure the grain runs parallel to the long dimension and its nice and straight and you will be fine.

Best thing I ever did was to buy a small bench circular saw ...

http://i6.photobucket.com/albums/y24...ps7100b8db.jpg

Means I can buy wood at local store ... and strip it to sizes I want ...

Nigel

thepiper92 01-02-2014 07:15 AM

Quote:

Originally Posted by Larry3215 (Post 935973)
It may be a balsa stick as its only designed for low power setups. I never use balsa sticks though - Ive had too many issues with them. Ive done many many stick mounted motors over the years. Its easy to make your own or you can go to HomeDepot and get a 1/2"x1/2"x36" long pre-cut hardwood stick. You will need to sand it down to 10mm but you can get several sticks for just a couple of bucks. Just check the stick to be sure the grain runs parallel to the long dimension and its nice and straight and you will be fine.

Any hardwood should be fine though I'm guessing. The plane should be really light with only 1300mah packs. It will get good run times too with only that much amp draw. I am getting 6-8 minutes with the bigger 3836 in the Mini Switch, although not full throttle often. With this plane, lighter will only help the run time on each pack.


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