ANAMALS14

After looking at a couple of baby bees sitting in my hoarding collection I got inspired . So I searched for plans for a curtiss goshawk , the only one that I found with any detail is for the latter retractible gear version. Not to be discouraged as there is only a slight difference in the fuselage , I am using the plans downloaded. Servos , receiver , esc , and lipo will come out of a hbk with a burntout motor. Found a throttle ring for the baby bee on e-bay. Now with all the combined wisdom of rcu forums I shall embark to create this aircraft. Might as well get some use out of this workshop I've built up over the years.

ANAMALS14

[sm=50_50.gif] After finding that the plans were printing at different scales due to the different zoom settings they were created at , I ended up getting tile print from blackflight to remedy that obstacle. Then at peanut scale found that a watchmaker would have trouble getting the electronics,fuel tank, and linkages in the fuselage. So 1\12th scale will be a workable build for this project. That will allow for better detail too.

BMatthews

You'll need to modify the plans to loose the big wheel fairings under the belly but yeah, the full size structures were basically the same other than that.

What span are you making this model? May I suggest something around 30 to 32 inches? This assumes that you'll be sticking with the basic rubber model construction plan but with such things as wing spars beefed up to withstand the higher flight loads of the glow and radio weights and aerobatics. If so you should be able to keep the weight at around 16'ish oz or perhaps slightly less for a nice flying speed that will look quite scale like. A Goshawk zipping around like a P51 would just not be right. But that is what you'd get if the wing loading gets too high.

And I thought the plan looked familiar. You got it from www.theplanpage.com didn't you?

ANAMALS14

Sharp eye , shure did get them from the plan page. The wing span resized to 32 1\8". Just how would be the recomended and lightest method of adding strength to the wings? I had thought of adding a spar on the bottom of the ribs, possibly going to spruce or popular. This is my first rc scratch build and I welcome all the advice I can get.

ANAMALS14

In the meantime I added a popular spar 3\32x6\32" under the 2\32" plan spars. Then added shear webs on the top of that, with shear web to be placed on top of the rear plan spar. By guestament I have 262g left for airframe , tank , landing gear,and linkage to keep it in the 16oz area. Shown is a dry fit of the upper wing with the aeliron linkage installed. After completion the apropreate ribs will be sawed at the rear webbing to become the aelirons. So how am I doing.

Mr Cox

There are so many ways do do this and as mentioned earlier here, the weight is important for a well flying plane. A strong and heavy plane will not fly nice and they still brake when they hit the ground. So careful design is the key, so just study a few well proven designs of similar size to get an idea.

I don't think that you really need poplar spars. Balsa spars are fine, but the spars should also be laid down in the other direction, you want to create an I-shaped beam to get the most strength out of a given amount of material. The shear web can be thinner, it should only go in between two spars to prevent shear motion. The ribs look unnecessarily thick to me and add weight more than strength (not a big deal, it just looks odd to me). Something that adds a lot of strength is to sheet the part in front of the main spar on both sides. This give a D-box that is very strong even with thin sheeting (around 1mm thickness is fine), again it is material away from the center of the cross-section that is most important.

Mr Cox

This thread suddenly went very quiet and I appologize if I sounded too negative, that was not my intention. Most things will fly and there will always be different oppinions regarding building techniques, that is the joy of scratch building. So just enjoy your build and don't mind the negative old fart in a small town in the middle of nowhere...

combatpigg

My Feedback: (3)

The Thanksgiving feast preparations takes time away from modeling....but your time is spent working on a different kind of bird.
Mr C....don't feel bad about posting good advice.
If ANAMAL has a weight budget figured out in advance for all the major pieces, he should be OK.

A thought...biplane wings can be built at almost half the weight of monoplane wings. They only need to be strong enough to withstand the crushing forces of iron on covering. By the time they are all braced and strapped to the plane, they form a very strong unit. I've built wings like this with just a fairly strong perimeter and thick ribs where the struts were to be attached. IIRC, those ribs were 1/2" thick contest grade. These wings have a single "topside only spar" that runs part span out to the "strut ribs" .

ANAMALS14

update on my progress. Got it mostly ready to sheet and cover after some caping on the tips and filling and sanding. Figured out how to access the servos , batt , and tank with a removable cockpit section. everything is slotted and drilled but for the elevators , have to wait on further assembly to get correct measurements. Last weight check still has it under 16oz Put threaded rod in the bottom of the fuselage struts to have an ajustable mount to the fuselage in case of any misalignment.

BMatthews

The structure and mods all look excellent. If the rest of the job sees the same attention to details and care as shown already this will be a winner for sure.

Keep in mind that they full size craft were not all that flast flying. At 32 inch span you may find that you want to use a 7x3 or 7x4 prop to slow down the average .049 and produce performance more in keeping with the original instead of having it fly around like a P51.

OzMo

My Feedback: (3)

ANAMALS14,
Nice work. Always fun to see craftsmanship in progress!

Kostas1

Is there any way to get from you a set of the plans;

vauxhall

Dave Fritzke has a C/L scale Gulf Hawk plan on his site, might be something to start with.
http://my.pclink.com/~dfritzke/gulfhawk.pdf

Kostas1

That is reallt awesome!

Thank you so much!