Tiny Trainer questions

[charlie256]

I want to build the Tiny Trainer and have printed these plans https://ftforumx2.s3.amazonaws.com/2019/01/208751_b19241977ac2bafa8ba96848e63eb59d.pdf

The problem is all I have is A3 size (29.7 x 42.0cm, 11.69 x 16.53 inches) UK 3mm foam.

So its not big enough to do the whole fuselage so I'm thinking I can do it in 2 parts as part of it bends in one place.
Same problem with the wing. So want to do each half in 2 parts and join them where they are supposed to bend.

Do you guys think this will work or is it better to try scale it down a bit to around 75%?

Thanks!

 

[herbertjalarcon]

Should work just fine...I've built some pretty big planes, and when I need, I just glue and tape the foamboard together before I cut out...and as for the wing, most FT wings are glued and taped in the middle!

 

[Ketchup]

You might need to make some changes to the build because of the 3mm foam (normal ft foam is 5mm), but it should go well. Also, your plane will be lighter! Good luck!

 

[charlie256]

What kind of changes would I need to make?

You might need to make some changes to the build because of the 3mm foam (normal ft foam is 5mm), but it should go well. Also, your plane will be lighter! Good luck!

 

[Mr.Grinch]

Just lay out your parts on the foam. Tape and glue sheets together as needed to complete the larger parts. Make sure you adjust the fold cavities from 5mm down to 3 to match the foam you are working with. I'm making a 150% tiny trainer so I have to work around similar adjustments.

 

[Hai-Lee]

The real issue you face is that the channels where the parts are glued and folded are designed to suit 5mm FB. The tail boom outside diameter must match the nose section internal diameter.
The nose cheeks are also designed to be in 5mm FB and this is to match the outside width of the powerpod.

The wing spar is 5mm in thickness and if using the original dimensions the wing profile will be altered because of the thinner material.

I have built the TT and many other FT designs using the 3mm FB and all of them require similar treatment.

If you keep the external dimensions as per the original design then the TT will fly very well.

Have fun!

 

[Ketchup]

What kind of changes would I need to make?

The 2 posts before this show exactly what you need to change.

 

[slowjo]

I want to build the Tiny Trainer and have printed these plans https://ftforumx2.s3.amazonaws.com/2019/01/208751_b19241977ac2bafa8ba96848e63eb59d.pdf

The problem is all I have is A3 size (29.7 x 42.0cm, 11.69 x 16.53 inches) UK 3mm foam.

So its not big enough to do the whole fuselage so I'm thinking I can do it in 2 parts as part of it bends in one place.
Same problem with the wing. So want to do each half in 2 parts and join them where they are supposed to bend.

Do you guys think this will work or is it better to try scale it down a bit to around 75%?

Thanks!

sounds like a great plane, sorry, plan

 

[charlie256]

Thanks, taking a bit of fiddling but hopefully will still work!

 

[charlie256]

The real issue you face is that the channels where the parts are glued and folded are designed to suit 5mm FB. The tail boom outside diameter must match the nose section internal diameter.
The nose cheeks are also designed to be in 5mm FB and this is to match the outside width of the powerpod.

The wing spar is 5mm in thickness and if using the original dimensions the wing profile will be altered because of the thinner material.

I have built the TT and many other FT designs using the 3mm FB and all of them require similar treatment.

If you keep the external dimensions as per the original design then the TT will fly very well.

Have fun!

I've managed to deal with all this but I am now up to the wing. Is it necessary to make adjustments so the wing spar is 5mm or can I just do it as is?
And if you think it's necessary to make adjustments what would you suggest?

Thanks

 

[Hai-Lee]

I've managed to deal with all this but I am now up to the wing. Is it necessary to make adjustments so the wing spar is 5mm or can I just do it as is?
And if you think it's necessary to make adjustments what would you suggest?

Thanks

The standard FB is 5mm thick. So the wing thickness is 5mm for the bottom piece plus the spar, (5mm), and finally the 5mm thickness of the top piece. This gives a thickness of 15mm. If using 3mm FB the top and bottom pieces make up 6mm total and so the spar needs to have a height of 9mm to make the wing curvature the same and thereby give the same lift as the original wing design.

You can use 3 thicknesses of the spar, (3mm FB), to get the correct wing profile or make a couple of vertical spars each being 9mm in height.

Where the rear of the bottom piece meets the upper piece on the Sport wing the thickness of the wing is normally 10mm, (top plus bottom thickness). When using 3mm FB you need ot add a spacer strip to return the wing profile to close to the original. At this point you can get away with an additional 10mm wide strip of the 3mm to make the thickness 9mm. This slight difference is workable and it actually increases the camber slightly and hence the lift is marginally higher.

The vertical main spars will be lighter but either approach will work!

Have fun!

 

[charlie256]

The standard FB is 5mm thick. So the wing thickness is 5mm for the bottom piece plus the spar, (5mm), and finally the 5mm thickness of the top piece. This gives a thickness of 15mm. If using 3mm FB the top and bottom pieces make up 6mm total and so the spar needs to have a height of 9mm to make the wing curvature the same and thereby give the same lift as the original wing design.

You can use 3 thicknesses of the spar, (3mm FB), to get the correct wing profile or make a couple of vertical spars each being 9mm in height.

Where the rear of the bottom piece meets the upper piece on the Sport wing the thickness of the wing is normally 10mm, (top plus bottom thickness). When using 3mm FB you need ot add a spacer strip to return the wing profile to close to the original. At this point you can get away with an additional 10mm wide strip of the 3mm to make the thickness 9mm. This slight difference is workable and it actually increases the camber slightly and hence the lift is marginally higher.

The vertical main spars will be lighter but either approach will work!

Have fun!

Thanks!

So I'm building the glider wing.
If I understood correctly you're saying where the spar goes I can just add 2 others directly on top of it and that will work?

 

[Hai-Lee]

Thanks!

So I'm building the glider wing.
If I understood correctly you're saying where the spar goes I can just add 2 others directly on top of it and that will work?

Yes you can! Just one thing to consider is that the extra paper can add weight and so you can remove the paper from the middle piece completely, (both sides), not only to save some weight but also to resist the paper from separating from the spar foam over time and causing additional problems.

Have fun!

 

[charlie256]

Yes you can! Just one thing to consider is that the extra paper can add weight and so you can remove the paper from the middle piece completely, (both sides), not only to save some weight but also to resist the paper from separating from the spar foam over time and causing additional problems.

Have fun!

Great thanks so much