# my part 103 ultralight build -thread

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#### Daedin Does Stuff

##### Member
Hey everybody, my name is Daedin and I plan to build a part 103 ultralight. I've been designing the ultralight for the past 11 months, and while that sounds like a long time note that I had school going on at the same time for 9 out of those 11 months, and school takes first priority. But I just finished with finals last week, and I can finally give my ultralight my full attention. So, I've been on HBA for a few months under a different account, I just figured that I ought to start a new account with correct details and everything. I've posted on the website before, and I love the community here! Everyone is so incredibly helpful, and I plan to be on here a lot more often because of that.
This thread is for questions I have about ultralight design, (I have a lot of them) and questions any of you guys might have about anything really.

So for my first question, can someone tell me how to estimate what my horizontal and vertical tail surface areas/volumes should be? I tried to use the vertical/horizontal tail sizing equations on pg 36 of Raymer's Simplified Aircraft Design For Homebuilders, but I couldn't tell what value I was supposed to put in for Swing, the wing area or the tail area? And why would I use the tail area in a problem that is meant to help me find the tail area? I tried the equation (pictured bellow) with the wing area for Swing, but I got a value of 39.16 ft^2, which doesn't sound right. Note that I have the tail 7.125 ft from the MAC, (or 5 ft from the trailing edge of the wing) a wing chord of 4.5 ft and a wing area of 124 ft^2.

Thank you, and I look forward to posting more on HBA!

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#### bifft

##### Well-Known Member
Swing is the wing area. The math looks correct. You're getting a large area out of the formula because your tail is kinda short.

#### proppastie

##### Well-Known Member
Log Member
You're getting a large area out of the formula because your tail is kinda short.
Distance from wing to tail

#### BobDaly

##### Well-Known Member
How Big The Tail (eaa62.org) should be helpful. The coefficients suggested by Raymer are for a general cross-country plane, not an ultralight. The tail coefficients for the Minimax ultralight are approximately Vhorizontal = 0.36 and Vvertical = .023, about the same as a J3 Cub. The Minimax has a fairly narrow cg range, 21-30% chord and the control pressures are light. It has a wing similar to the one you're contemplating. The tail arm is about 8.5 ft on the Minimax.

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#### Daedin Does Stuff

##### Member
Alright this is a weird question, but anyone know where I could buy a wheelbarrow like the one bellow? All the wheelbarrows that I've seen have rounded edges which get in the way. I believe that most wheelbarrows do not have edges like the one bellow because it makes them harder to cast, and straight edges make them harder to dump things out of but I would really like one like that because they allow for easier construction. With a regular wheelbarrow, you can't nestle a 1x1 into the corners of the barrow, but with a boxy wheelbarrow with edges, you could easily do that. I realize that this is an odd thing to post on a forum about airplanes, but I assure you that this is airplane related, and I would greatly appreciate any help.

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BJC

#### Daedin Does Stuff

##### Member
How Big The Tail (eaa62.org) should be helpful. The coefficients suggested by Raymer are for a general cross-country plane, not an ultralight. The tail coefficients for the Minimax ultralight are approximately Vhorizontal = 0.36 and Vvertical = .023, about the same as a J3 Cub. The Minimax has a fairly narrow cg range, 21-30% chord and the control pressures are light. It has a wing similar to the one you're contemplating. The tail arm is about 8.5 ft on the Minimax.
I used the values you listed in your post and I got a volume of ~17"x17"x1" for the horizontal volume, and a volume of ~11"x11"x1" for the vertical volume. Thank you very much, your advice was really helpful. I'm going to round out everything and go with a volume of 24"x24"x1" for the vertical tail volume and a volume of 12"x12"x1" for the horizontal tail volume.

#### Daedin Does Stuff

##### Member

BJC
Yeah, I think so too. I'm probably just going to end up buying a regular wheelbarrow since those boxy ones don't seem to be commercially available. It's not like I can't make a traditional wheelbarrow work for my purposes I just believe that one with edges would be more convenient.

#### Daedin Does Stuff

##### Member
Well thats exactly what I'm looking for but its also worth half of all my savings. I think that I'm going to try to make do with a regular wheelbarrow. Thank you for finding it though.

#### patrickrio

##### Well-Known Member

BJC
looks like a cement/mortor mix wheelbarrow.

#### mcrae0104

##### Well-Known Member
HBA Supporter
Log Member
Well thats exactly what I'm looking for but its also worth half of all my savings. I think that I'm going to try to make do with a regular wheelbarrow. Thank you for finding it though.
I’m not trying to pick on you, but 295 AUD is $228.37 (assuming you’re in the US). Two times this is$457. Homebuilding a wheelbarrow seems perfectly reasonable in that scenario.

#### BJC

##### Well-Known Member
HBA Supporter
I’m not trying to pick on you, but 295 AUD is $228.37 (assuming you’re in the US). Two times this is$457. Homebuilding a wheelbarrow seems perfectly reasonable in that scenario.
From his profile:
A part 103 ultralight built around a wheelbarrow.
No past projects, the plane that I'm working on now is really the first major engineering project I've ever undertaken.
Edit: He is 13 years old.

BJC

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#### mcrae0104

##### Well-Known Member
HBA Supporter
Log Member
Edit: Snark redacted.

What we have here is a genuine aspiring aviator (to be encouraged) and not a crank. Good for you, Daedin.

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#### Daedin Does Stuff

##### Member
I feel like I'm asking all the wrong questions for all the wrong reasons here. Sorry for wasting your time with the wheelbarrow question I believe that it was a stupid question to ask. And yeah as BJC pointed out on my profile I'm 13, have little to no engineering experience and am trying to design and build a part 103 ultralight around a wheelbarrow with a \$600 budget. I realize that that isn't the best combination for a good ultralight, but I've been chipping away at this project for nearly a year and I'm very dedicated to seeing it through.

Now I've got another question, how do I determine what reynolds number my plane will be going at at cruise? I think that I've got a rough conceptual design that I'm happy with, now I just need to optimize it. I want to start doing by changing what airfoil I'm using since I believe that a high-lift airfoil with a bit more camber than the Clark-Y that I have now would work better for my purposes. Overall, I want to create a high-lift wing so that I don't have to create too much thrust. (around 20-30 hp is my goal) What I think I should do in this situation is use xlfr5 to figure out when lift=drag on my plane and then determine how much thrust it takes to produce that much lift, then figure out the reynolds number, but xlfr5 keeps on giving me weird results on the Clark-Y that don't line up with the results that I found on airfoiltools.com. (I think that xlfr5 uses the results you get from the analysis you do on .dat file of the airfoil you're using for the 3d model thingy that you make after you do the analysis.) Anyone know a different program or something that might help me here? Or just any advice in general would be appreciated.

-Thank you very much, Daedin.

#### Victor Bravo

##### Well-Known Member
HBA Supporter
Daedin, you write and communicate very well if you're 13 years old. Congratulations... you will be treated like an adult on this internet forum, and because of that you will enjoy having access to a large amount of experience and knowledge here.

What parts of the wheelbarrow do you want or absolutely need to use in the ultralight, and why?

#### Daedin Does Stuff

##### Member
Daedin, you write and communicate very well if you're 13 years old. Congratulations... you will be treated like an adult on this internet forum, and because of that you will enjoy having access to a large amount of experience and knowledge here.

What parts of the wheelbarrow do you want or absolutely need to use in the ultralight, and why?
Thank you, I am very lucky to be able to be apart of a community of such knowledgeable and helpful people. I'm going to use the entire wheelbarrow minus the little supporting legs in the back, and with the handles chopped off. The wheel in the front will be used as an overkill front wheel in a tricycle landing gear configuration. The 2 back wheels haven't been designed yet, but they will not be a part of the wheelbarrow. None of the wheelbarrow is strictly necessary, but I first included it in the design because I was in a bit of a rut. I didn't like any of the designs I was making, but I did a little yardwork for a neighbor and it occured to me that I could use a wheelbarrow in my design. I figure that a wheelbarrow is made out of strong metal materials and should do just fine as a seat/cockpit area.

#### Jerry Lytle

##### Well-Known Member
Have you checked out the Dormoy Bath Tub? Sounds alot like what your are contemplating, it will look something like this.

General characteristics

• Length: 13 ft 5 in (4.09 m)
• Wingspan: 24 ft (7.3 m)
• Wing area: 85 sq ft (7.9 m2)
• Gross weight: 425 lb (193 kg)
• Fuel capacity: 2 US gallons (7.6 litres)
• Powerplant: 1 × Heath-Henderson B-4 , 20 hp (15 kW)
A good place to start. Dormoy did not use a real bathtub, too heavy, as you will find the same with a real wheel narrow. Build your own wheelbarrow, much lighter.

#### Victor Bravo

##### Well-Known Member
HBA Supporter
The wheelbarrow "bucket" section will not provide enough of a seat, and will not provide sufficient places to attach the rest of the structure.

So the engine will have to be mounted on a separate structure which is riveted to the front of the wheelbarrow. Same for the tail and wings. Finally, you will have to install a proper seat and control system into the wheelbarrow.

What all this means is that you will be designing and building all the parts of a proper airplane, and then finding a way to attach a wheelbarrow into the middle of it, because you wanted a wheelbarrow.