Decalage angle

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Eugene

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The way I see it, at some point I will need to find a way to reinforce tail boom. This situation was calculated for 50 hp engine. We doubled up engine power, but we didn’t do anything with kale to compensate for much higher load. Maybe I can come up with something in time. As of right now tail boom is surrounded by form and it is very rigid. And it feels very good and solid.
83EDA93C-EA02-470F-BB3F-13C1E592FDD9.jpeg
 
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proppastie

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I'm impressed with the way you are making a different airplane with the foam like that. I didn't think it would hold together but that it does opens up possibilitys for simple homebuilder aircraft development.
 

Eugene

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I'm impressed with the way you are making a different airplane with the foam like that. I didn't think it would hold together but that it does opens up possibilitys for simple homebuilder aircraft development.
Not sure if you can see smile on my face between the lines, but believe me, I am having best time of my life!!! This is for sure completely different experience in comparison to everything else I have done in my life. And best part - you can do this aircraft research and development for very little money. Sure glad that I didn't listen to most EAA members who was recommending to sell and start enjoying life. :)
 

plncraze

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Don't retract the gear. Instead build little clamshell doors to enclose them-google Bede Speed Pants. They were on a few BD-4's.
 

Eugene

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Don't retract the gear. Instead build little clamshell doors to enclose them-google Bede Speed Pants. They were on a few BD-4's.
Yes, it is on my list of things to do for main wheels and front one. You can see on picture below that in real flight main wheels hanging down at much more aggressive angle then my blueprint shows. So, they acting like air scoops with about 5feet (1.5 meter) arm from engine thrust line. So, it's not only drag on Skyboy, it is drag X arm = moment, that needs to be balanced with horizontal tail that positioned below engine as well. Snowballing drag effect!!!

Screen Shot 2019-07-02 at 16.09.12.jpeg IMG_0889.jpeg IMG_1642.jpeg 46665329_2340129276015575_2953391070903271424_n.jpeg
 

Eugene

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This is my attempt to create a visual explanation about what will happen to horizontal tail on Skyboy when drag will be reduced at low part of fuselage. Or for that matter anywhere else on airplane. Hopefully I did this correctly. Same power setting and as a result same drag, but only at different speed. Different speed equals smaller angle of attack. So, moment between engine and drag will be the same on all three pictures, only difference is that horizontal tail will be assuming different position every time, but will need to generate exactly the same balancing force. So, on top picture horizontal stabilizer needs to be adjusted lower to be in line with elevator. On bottom picture horizontal stabilizer needs to be moved up a little to be in line with the elevator as well.

6D7A3BF4-D2B3-47E2-9BE5-F5935910F8F7.jpeg


This way we can make conclusion:

High drag aircraft = large decalage.

Low drag = small decalage.

And this is why the very top aircraft on my picture is flying just like with extended flaps. No flaps needed there. The very bottom Aircraft will for sure benefit from flaps during landing.
 
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Eugene

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Screen Shot 2020-02-08 at 20.48.54.png
Not sure if we can use this statement for possible explanation for why is Skyboy flies completely different with passenger. Maybe horizontal tail simply too small to handle forward CG position with 2 people.

Screen Shot 2020-02-10 at 22.01.28.png
 
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Eugene

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Don't retract the gear. Instead build little clamshell doors to enclose them-google Bede Speed Pants. They were on a few BD-4's.
Still thinking about good way to make wheel pants work with my new foam rear cowling. so far no good ideas from interference drag stand point.

IMG_3728.jpg C6A8A73B-C999-48CE-900B-D64C17853E7D_1_201_a.jpeg A2CDE415-7A80-4B86-B0E5-A53F583518CE_1_201_a.jpeg 324824C7-E458-4CB6-9D98-2FB37321922D_1_201_a.jpeg 7093150C-6084-4441-A51F-DDFB2D4BDF7D_1_201_a.jpeg 94514F8A-7D60-4A99-9EFD-65F17BA52624_1_201_a.jpeg B7478B79-3B10-49D2-A2F9-1956CB5F669D_1_201_a.jpeg 8FC1D1BA-2697-4CD6-A6D8-F800E6337563_1_201_a.jpeg 40C14F90-FABB-4610-9DB4-9EA56CC22BFA_1_201_a.jpeg
 

Eugene

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E4AE753A-8F4E-47C7-9A40-65CD0C595278_1_201_a.jpeg

I wanted to do this for many reasons.

I wanted to see how my wheels look in level flight situation to improve wheel pants.

I was hoping to remove shock absorbers and cycle gear up and down to make sure that wheel pants not interfering with my new cowling during landing.

Everybody was telling me that aircraft should be strong enough to hang up in there by this 4 points. But I wanted to hear your opinion.
 

Eugene

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Started working on the bottom of my new piece. Looks like it is additional area of aprox. 16 sq.ft.(1.5m). Hopefully this area will work for me and not agains me. I need to do a lot of sanding before it will be ready for test flight.

41C3EDEF-A665-44C8-AEEC-9A74626D1C28_1_201_a.jpeg BEFB591A-AB02-47E1-90C8-8348492FB50F_1_201_a.jpeg EB03AAFC-A2F9-4C04-B378-1864E1733C19_1_201_a.jpeg F64A6975-B9D5-46C5-8D6F-EE0B98F5CCE6_1_201_a.jpeg
 

fly2kads

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You're getting pretty good at this foam carving thing. Ready to go into business making surfboards? :)
 

Eugene

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You're getting pretty good at this foam carving thing. Ready to go into business making surfboards? :)
Playing around with foam is actually fun and easy part. Someday I will have to stop playing and have to start building this piece. Not sure how easy that will be. From what I am learning looks like very slow process with a lot of attention to details. We will see.
 

Eugene

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I was making some progress today and result is another question. Foam area marked with black marker I think will need to be removed to be level with airflow.

IMG_3756.jpeg IMG_3755.jpeg IMG_3754.jpeg IMG_3753.jpeg IMG_3752.jpeg

Airplane on picture below in my future level flight position = 1° AoA to the bottom of the wing. So, foam between wheels and fuselage should be removed to be level?

CE709E6C-BEAE-4634-B199-65570B22346A_1_201_a.jpeg 28492B1D-C14E-4635-8BE2-A668D4EF2325_1_201_a.jpeg 40EE8A44-95E0-4C69-A361-32C85BD5A2CC_1_201_a.jpeg C1214C8C-EA8E-48C1-AC3E-B62F668948CE_1_201_a.jpeg
 
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