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Scratch Build Project Airway XY-9 Test Aircraft - 4/5/2008 4:35:00 PM   
Lafayette


 

Posts: 15
Joined: 9/10/2007
From: Geneva, , SWITZERLAND
Status: offline 		Hey all of you guys.

I am new to RC Universe but I am sure not new to Scratch Building. For me designing airplane blueprints and building the airplane is 3/4 the whole fun- the rest is relaxing and flying what I built. I am currently in for a project airplane I call the Airway (my imaginary brand which I hope making real when I finally grow up- I am 13 years old) XY-9 Test Aircraft. It is not a small airplane with a wingspan of 1.5 meters and a length of 1.4 meters. I was working on the plans/blueprints for this airplane for 2 and a half weeks now, and I am almost done with everything. Soon will come the part with the Lift and Drag equations to figure out whether it will be actually worth building it. I used aerodynamic formulas for real size airplanes for my previous aircraft, but they didn't seem to compliment small R/C aircraft. Does anyone know a link to aerodynamic formulas for R/C airplanes? Okay, let's get to the point, guys can all of you who are actually professionals at this tell me if this airplane seems to be proportional and if it will fly with a .40 or a .30 gas engine? I am looking forward to .30 engines with throttle control. Here are the blueprints/plans. Please suggest any improvements I could make on the plans before I print a huge sheet of paper and waste ink... .

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       Post #: 1

RE: Scratch Build Project Airway XY-9 Test Aircraft - 4/5/2008 7:23:51 PM   
BMatthews



Posts: 9015
Joined: 10/4/2002
From: Burnaby, BC, CANADA
Status: offline 		It will fly but I'd stick with the .40. A 1.5 meter span model is typically powereed with more like a .60 or 10cc. Especially for extended vertical maneuvers.

It's also hard to tell since your wing chord is not shown on the fuselage plan but it looks like your tail areas are a little too small for the wing. The horizontal tail area should be up around 15 to 18% and the vertical tail area around 8 to 10% of the wing area.

_____________________________

Witty saying to be plagarized shortly.....

(in reply to Lafayette)
       Post #: 2

RE: Scratch Build Project Airway XY-9 Test Aircraft - 4/5/2008 9:08:49 PM   
Lafayette


 

Posts: 15
Joined: 9/10/2007
From: Geneva, , SWITZERLAND
Status: offline 		Thank you BMatthews. Maybe you cannot see because of the plans, but the tail area is actually about 12-13 % of the wing area. I thought about the tail surface as well for a long while, thank you for pointing that out straight away. I might change it before printing to be a tiny bit smaller, again thank you. I will go over to my local club and ask if anyone there is any of a scratchbuilder. Maybe it will be easier for them to tell seeing the actual plan. Thank you for commenting. I will go over to my local balsa supplier with my dad next weekend- ahhhh cant wait to start building- and buy all the necessary equipment. I am guessing the workboard along with the knives and glue and the actual balsa and plywood and the aluminum wing tubes-that will all cost quite a penny. I am not too good at economics because I usually build from trash can scrap material, I do not know the average balsa prices. What will you estimate the whole thing- without any radio equipment- to cost if I will buy 2 mm and 5 mm balsa fuse spars, 4 mm plywood spars, 3 aluminum tubes different sizes, a lot of 2 and 3 mm blasa sheets and some 1 mm plywood sheets. Wow, I jsut noticed it is quite a lot, but what will it cost? 90 dollars? 100?

Thank you everyone,
Yishht.

(in reply to BMatthews)
       Post #: 3

RE: Scratch Build Project Airway XY-9 Test Aircraft - 4/6/2008 3:29:12 AM   
BMatthews



Posts: 9015
Joined: 10/4/2002
From: Burnaby, BC, CANADA
Status: offline 		The cost of materials will depend a huge amount on your local prices. But yes, over here I would expect the material to build something that large using the methods you are showing to run about that much. But you'll have some left over.

Is this your very first project? If so you've done a very good job designing it for the most part. You've chosen to use a very thin airfoil. Far thinner than many folks would use on such a model. If you stick with that then you will want to use spruce or at least basswood for the wing spars and to use vertical webbing to join them so they form a proper I beam like structure.

If your horizontal tail is only 12 to 13% of the wing then it needs to be made larger. Or if your wing is actually represented by the single line on the fuselage side view then you're fine. However if that single line is the wing then your nose is esceedingly long and the model will likely come out quite nose heavy. Perhaps a new side view with the wing section properly shown can clear this up.

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Witty saying to be plagarized shortly.....

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       Post #: 4

RE: Scratch Build Project Airway XY-9 Test Aircraft - 4/6/2008 9:43:48 AM   
Lafayette


 

Posts: 15
Joined: 9/10/2007
From: Geneva, , SWITZERLAND
Status: offline 		Okay, thank you.

The wing is actually drawn on the plans. It can be easily identified by the writing "Airway XY-9". The reason that it looks nothing like an airfoil is for the reason that I drew not the root of the wing but the tip- which is a wingtip and looks like that from a side view (look at wing plans). That grey line on top of the wing is the place for mounting servos batteries receiver etc. Again, just to confirm, it will cost about 100 dollars? The thing is that I live in Switzerland now and the price for a 2 mm balsa sheet (or maybe 1 mm no idea) is 6 francs- about 5 dollars. Also, the fuselage is fully sheeted except for a hole in the fuselage you see as a deformed rectangle at the end near the vertical and horizontal tail fins. Will a .40 engine run well on this airplane? I am currently stil in the process of finishing up the fuselage formers and doing aerodynamic calculations.
This is my first serious build, yes. But I built some kits and some airplanes by plans I made myself or other people's plans. This will be my first serious, big airplane though. Will you say it will handle well in the air? I wanted a big nose and tail lengths to have a good nose and tail arm for better stability and performance during flight. I am loking forward to this airplane as a trainer airplane but also a heavy sports airplane going to speeds of up to 70-80 miles per hour during a descending maneuver. Also, I was designing this airplane for it to feel confident in the air and not go all over the place. I think that I achieved all those characteristics- but please give me advice.

Yishht.

(in reply to BMatthews)
       Post #: 5

RE: Scratch Build Project Airway XY-9 Test Aircraft - 4/6/2008 7:31:22 PM   
Lafayette


 

Posts: 15
Joined: 9/10/2007
From: Geneva, , SWITZERLAND
Status: offline 		Well while I and some of the people who follow this thread anxiously wait for the build to begin, I burn time with useless things. Here is my latest project for my sister's room- a giant balloon thingy- xD. I am done with my plans as well just have to calculate the lift and coefficients and aspect ratios and that stuff- fun stuff. Here are pics who aren't yet as interesting. I don't kow if the ballons will fly with a .40 engine... \

Yishht.

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(in reply to Lafayette)
       Post #: 6

RE: Scratch Build Project Airway XY-9 Test Aircraft - 4/6/2008 11:18:17 PM   
BMatthews



Posts: 9015
Joined: 10/4/2002
From: Burnaby, BC, CANADA
Status: offline 		OK, I think I see the wing now. It's under that dark grey line. Keep in mind that the RCU servers automatically reduce the size of any images. So I can only just barely make it out in my version.

This is a REALLY big fuselage in that case. I understand that you're making it a "could be scale" design but you're going to add a lot of weight and complexity by making it so large. And I think the nose is still too long unless the "real one" is to be powered by a small and lightweight turbine option.

_____________________________

Witty saying to be plagarized shortly.....

(in reply to Lafayette)
       Post #: 7

RE: Scratch Build Project Airway XY-9 Test Aircraft - 4/7/2008 6:21:21 AM   
Lafayette


 

Posts: 15
Joined: 9/10/2007
From: Geneva, , SWITZERLAND
Status: offline 		Okay, thanks.

I don't understand the could-be-scale thing because this is my own design and not a scale version of some airplane. I understand that it is hard to see on these blueprints, but the fuselage is 1.3 meters which is 20-25 cm smaller than the wings. Also, don't forget that the airplane has flaps to help support it in the air. I agree with your question WHY? is the airplane so big. I am making this airplane for testing out new aerodynamic ideas and designes on it, and for that I need some ability to get inside the airplane and the fact of making it bigger makes improvements easier to make. What do you mean a turbine version? I don't have any idea of the nose-heaviness- I always planned on a .30 engine. Also, don't forget the tail is bigger than the nose, which makes it a bit heavier and the engine weighs only 300-350 grams. If proper balanced, I think it will all come out right- but it all ends up on testing doesn't it? . Okay I have to leave to school.

Yishht.

(in reply to BMatthews)
       Post #: 8

RE: Scratch Build Project Airway XY-9 Test Aircraft - 4/8/2008 6:22:20 AM   
Lafayette


 

Posts: 15
Joined: 9/10/2007
From: Geneva, , SWITZERLAND
Status: offline 		Well, hi BMatthews. I think that the airplane will definitely fly. I found a very useful and quite an accurate online aerodynamics calculator on www.RCAdvisor.com . This is a very nice calculator which is meant for electric airplanes- but suites gas airplanes as well. I hope there will soon be an update to the calculator with gas engines . If you want to go there, become a member of the site for FREE and then you can use all the features of that calculator. That calculator counts drag ans lift and their coefficients, and all the other things like zero lift angle, wing loading and all that. So, here is what I came up with:

Airplane Dimensions:

Wingspan total = 147.9 cm

Length total = 123.2

Height total = 31.4 cm w/o rudder

Specifications:


Airplane Efficiency at 100 % Thrust at 60 km/hour:


Wing Loading = 28.464 oz/ft^2

Wing Lift = 2.5 kg

Thrust = 1.468 kg

Wing Reynolds Number = 109.906 k

Total Drag = 0.108 kg

Climb Rate = 320.088 km/hour or 88.913 m/sec


Airfoil Efficiency at 100 % Thrust at 60 km/hour or at .49 % Mach Speed:


Lift Coefficient = 0.404

Drag Coefficient = 0.025

Pressure Drag Coefficient = 0.019

Zero Lift Angle = -2.195


Guys, please tell me is the height of my airplane okay? Because I have small doubts on that if 31 cm will be okay for a 1.5 meter span wing. Will it be okay or should I make it smaller? Keep in mind the airplane will have to fly with a .40 or a .45 max .50 engine.

Thank you,
Yishht.

(in reply to BMatthews)
       Post #: 9

RE: Scratch Build Project Airway XY-9 Test Aircraft - 4/11/2008 3:34:06 AM   
BMatthews



Posts: 9015
Joined: 10/4/2002
From: Burnaby, BC, CANADA
Status: offline 		I think you may have misunderstood some of the numbers. There's no way your model will fly level at 320 km/hr let alone climb at that rate.

Otherwise it all looks good as things go. I would say that the wing loading seems a little high even for a larger model of this sort. I'd also suggest that a 3 kg final ready to fly weight would be more realistic. After all, the engine and muffler are around .6 to .7 kg on their own.

The thrust you show at 1.4 kg isn't right. A modern .60 will easily lift a 3 kg model of this sort vertically. So power will NOT be an issue.... but it won't lift it at 320 kph...

The fuselage IS tall but you said you wanted to make this a prototype of a possible man carrying airplane. That means you would need it to be that large. But yes, it is far deeper than needed for holding the RC equipment.

_____________________________

Witty saying to be plagarized shortly.....

(in reply to Lafayette)
       Post #: 10

RE: Scratch Build Project Airway XY-9 Test Aircraft - 4/11/2008 6:23:21 AM   
Lafayette


 

Posts: 15
Joined: 9/10/2007
From: Geneva, , SWITZERLAND
Status: offline 		Thank you, and yes it will be a prototype airplane. Maybe I did misunderstand the climb rate- 320 kph is the slimb rate of an airliner shortly after take off... lol. I think 9 meters per seond will be more realistic won't it? I just printed out the plans for the wings on my out-of-ink printer. It came out all pink... But that's okay I had no other choice since I am going to buy balsa for the 2 wings tomorrow, and I will need the blueprint for relativity. The wing does look too thin, but that will give it low pressure and friction drags. It will all come out fine. Also do you know any good freeware tile print porgrams with adjustable scale? Because I printed on a non registered program with NOT REGISTERED going all over my wing plan. LOL.

Thanks,
Yishht.

PS. Sorry for posting this on other topics, but it seemed as people forgot about my thread here and I really needed help.

(in reply to BMatthews)
       Post #: 11

RE: Scratch Build Project Airway XY-9 Test Aircraft - 4/11/2008 4:38:32 PM   
Lafayette


 

Posts: 15
Joined: 9/10/2007
From: Geneva, , SWITZERLAND
Status: offline 		Printed and glued together wing plans. LOOKS SO COOOOOOL, seriously guys. When I glued together the plan seemed to have come alive or some sort of thing- it was amazing. Tomorrow I am going with my dad to buy blasa and other accessories for the wings. Also need a balsa workboard- not gonna build on my table... would have if not my mom... . To make the wings staright I am going to launch for myuncle's technique
Will have a right angle trinagle ruler and many pins/nails (which ones are better? please suggest). I will put down my plan on the workboard and work my way through it nailing the pins on each side of the rib at a 90 degree angle. Thise will help the wing be right and not be twisted. I am really SCARED of this build. In fact, I am terrified. Pleas sooth my with comments on how to build the airplane properly. Especially a wing and how to glue the balsa on (e.g. use CA glue or Elmer's glue type of thing).

Yishht, SCARED AS HELL OF THIS AIRPLANE.

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(in reply to Lafayette)
       Post #: 12

RE: Scratch Build Project Airway XY-9 Test Aircraft - 4/13/2008 8:55:49 AM   
Lafayette


 

Posts: 15
Joined: 9/10/2007
From: Geneva, , SWITZERLAND
Status: offline 		Well, after waiting through the boring and annoying rc universe Forum shutdown, I can finally post something. I did go to my hobby store and I did buy neccessary material to start the build. I atached pictures of all I bought in this post. Although, I didn't want to make to much of a balsa mess, so I went with buying only material for 1 whole wing and and extra 2 mm balsa strip for ribs of the other wing. I was headshaken to find out all cost 160 dollars!!! Durn balsa is expensive nowadays. Although, I went along with pine spars for my wing and first 6 ribs will by 2 mm beech plywood. That plywood wil be enough to make fuse formers as well. Question- should I make the whole of fuselage formers out of 2 mm plywood, reinforsed with balsa and pine spars? Remember, this is a .60 gas engine airplane. I also went along and bought 2 Futaba S3003 standard servos for 25 dollars each. These serve for 1 aileron and 1 flap. Will have to buy another 2 of these for the other wing and 2 servos for rudder/elevator. Although, I already ran into difficulties which are literally ugly. Those standard servos are freakin' tall- and so they will stick out of my 1.5 cm relatively thin wing. What should I do? No way I am going to increase the thickness of the wing I already cut out the blasa pieces for sanding them down to my airfoil with a template- plywood template. I though I should just let it stick out- but then I can also make a styrofoam bump in the wing which will I guess look okay. This bump will also direst the air along the wing chord- seems a good idea. Please give me your ideas as well.

Bye,