[michel gravelle]

Hi Thier

Does anyone know if dope bonds to epoxy ? :
If it does not , I m in deep DO DO . Or will I have to sand off the epoxy


Mike

[scaleguy]

Originally Posted by michel gravelle

Hi Thier

Does anyone know if dope bonds to epoxy ? :
If it does not , I m in deep DO DO . Or will I have to sand off the epoxy


Mike

Mike,

What do you need to paint over that has epoxy on it? Are you talking about a wing center section? Oh and the answer is NO the dope will not bond to the epoxy.

[michel gravelle]

Hi Jim

Its for my LT-40 , I did the plane in fiber glass and because the plane came out too heavy I decided to rebuild the tail end in dope to practice the dopeing prcedure . The LT-40 has open bay areas on the tail end and the rear of the fusalage . I guess I will have to sand it all off .

Thanks

Mike

[scaleguy]

Originally Posted by michel gravelle

Hi Jim

Its for my LT-40 , I did the plane in fiber glass and because the plane came out too heavy I decided to rebuild the tail end in dope to practice the dopeing prcedure . The LT-40 has open bay areas on the tail end and the rear of the fusalage . I guess I will have to sand it all off .

Thanks

Mike

You could try using Monokote. It will be lighter then dope and fabric. You will need to apply Balsarite over the epoxy though.

if you glassed the whole airframe I fear you will be to heavy.. your wingloading will be way higher then the designer ever took into account. What was the weight of your fibreglass cloth, 3/4oz, 1oz, 2oz....

Did you use Polyester Resin or real Epoxy? Whoose Epoxy?

Do you know the total weight of the airframe as it stands now?

[michel gravelle]

Hi Jim

I bought the LT-40 to improve my building skills . I covered the wings with 3/32 balsa sheeting and than applyed Sig fiberglass cloth 3/4 oz , and applied Z-poxy . The plane came out 2 lbs overweight . This project has now have to be saved , which I will do , it s just part of the hobby . Which I don t mind at all . I will have to sand off all the Z-poxy and finish the open bay area with dope . If nessaery I will rebuild the wings , It just a matter of getting the right info . Which I should of done at the very start . But I didn t have the right questions to ask , I m more into it now , than I was at the time .

Thanks Jim


Mike

[Vulcan1]

Mike,
Before I would trash the wing or build a new one I would try a few things. Glassing over open framework is not good but over the 3/32 balsa sheet is. Lots of strength there but if you did not scrape or remove as much of the epoxy when applying the weight will add up.
It all comes down to what you want to apply over the glass and if is a cloth covering or similar material you would take it out to the ldg. & trl. edges. Seal around the edges then shrink. The trick is what to use for attaching the edges. Balsarite or something like that might work over the framework.
Maybe somebody else has some suggestions also to help out. You could let us know with a pic what you have or want to cover as it would help.
John

[michel gravelle]

Hello John
Thanks for youre support and info .
Heres the story .

This LT-40 was to improve my building skills , which is being accomplished . My intent was to make the plane as strong as possible . because I didn t have the information that I needed on hand , I decided to cover the plane in fiberglass and z-poxy . I covered the open bay areas with 3/32 balsa , this includes the tail section ( bigtime mistake ) , which made the plane way to tail heavy , so this is my solution .

First I will scrap the tail section , rebuild new , second , I will be sanding off all the z-poxy and fiberglass down to the bare wood ,right up to were the trailing edge of the wing attaches to the fusealoge and restart all over again.

I already have one ARF , and I don t like it at all . I m not knocking ARF s , but I believe it is a matter of preference . I want my planes to be durable and long lasting . I will not be getting out of this hobby any time soon . I have decided that all my projects will be covered in dope . this may be the long way of doing things but I believe it is the best result I will get for what I want and I heard that it is a beautiful finish , I will not mind putting in the time at all , now , back to the LT-40

When building the wing I made sure that I removed all of the z-pozy that I could , like I mentioned , the biggest problem is the tail section , my next step is to cover it in Koveral and nitrate dope . Here s a question?

When covering the tail surfaces do I cover them when they are joined or do I cover them seperatly , because I will be useing epoxy to glue everything to-gether, this is were I am presently confussed .

I m hopping to hit 6.5 LBS . I will be putting in a 50 size engine .

All this is to get to the project that I really want to build , a DC-3 . I have a Elder 40 to build before I do that . As you can see I plan on doing a lot of learning before I can even get to build the DC-3 . And in the future I want to get onto SCALE , like WW 1

I hope youre week-end isn t like mine RAIN RAIN RAIN .

Thanks John

Mike

[Flypaper]

There are only three places where strength is needed. that's the firewall,the landing gear mount and the wing mount. Build the rest as light as you can. Light planes are less likely to get pranged. Heavy planes don't fly well and because of this get pranged more often. Higher stall speeds and such.

[scaleguy]

Mike,

As flypaper stated a model airplane should be built to fly, not to crash. Build it as light as possible while still maintaining structural integrity.

Most kit manufactures have been in the business for a while and they know what works. I too use to "beef up" my planes as I didn't think the designer knew what he was doing at times. The bad thing with this is that when a crash does occure, and they will, there is more inertia builtup in the model when it makes contact with the ground in a heavy model and when all that weight tries to come to anabrubt stop, more damage is caused then if a light, well engineered and built model crashes.

I think your choicer of sanding down to the wood is a good one n the wings. I would go one step further and cut out the wing bays again and just cover the entire wing in Sig Koverall. The good thing with this stuf is it can be ireoned on like Monokote then painted over with dope. Rember to sgive a coat or two of Clear Buyterate Dope over the covering first before painting with colours.

[Vulcan1]

I agree with you Jim but after reading again I think his comment was improve his building skills. I take it he applied the sheeting and glass to see what type of finish he would end up with after. May be the expensive way but better than on a big scale job. I still like glassing but it takes a lot of work to keep the weight down.
John