Sponsor Message:
Aviation Hobby Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Model Commercial RC Aircraft  
User currently offlineVSXA380X800 From United Kingdom, joined May 2004, 421 posts, RR: 1
Posted (10 years 1 month 2 weeks 1 day 17 hours ago) and read 9799 times:

I have a A380-800,A340-500/600, A320 Family and a 777-300,all are 1/50-75. I'm thinking of doing the craziest thing to cut out a hole in the in the engine case and make a similar engine using 2 race car motors per engine case. With a larger fan in the front and a smaller behind. Then I might have it controlled by RC.

Has any one tried this with their model aircraft and what tips or advice I should look at ?

[Edited 2004-07-20 20:47:20]

[Edited 2004-07-20 20:56:07]


4 decks 4 engines 4 long haul
15 replies: All unread, jump to last
 
User currently offlineDoug_or From United States of America, joined Mar 2000, 3404 posts, RR: 3
Reply 1, posted (10 years 1 month 2 weeks 1 day 15 hours ago) and read 9772 times:

Q1. have you ever flown an RC aircraft?

Q2. how heavy are the models?

Q3. what kind of airfoil do they have?



When in doubt, one B pump off
User currently offlineVSXA380X800 From United Kingdom, joined May 2004, 421 posts, RR: 1
Reply 2, posted (10 years 1 month 2 weeks 1 day 12 hours ago) and read 9762 times:

A1. Yes
A2. It weights about 2 1/2 killos(6 pounds)
A3. If you mean what its made of its a Solid Plastic or Fiber Glass.

Here's a picture of what it looks like. Its EXSACTLY like it but its closest I could get.

http://www.aviationmodels-online.com/AM/VA346-6.htm



4 decks 4 engines 4 long haul
User currently offlineVSXA380X800 From United Kingdom, joined May 2004, 421 posts, RR: 1
Reply 3, posted (10 years 1 month 2 weeks 1 day 10 hours ago) and read 9759 times:

Regarding rely 2; I will be cuting out the part of the Wing, Horizontal/ Virtical stableizer for controll.


4 decks 4 engines 4 long haul
User currently offlineSplitzer From United Kingdom, joined Feb 2004, 151 posts, RR: 0
Reply 4, posted (10 years 1 month 2 weeks 12 hours ago) and read 9734 times:

You would have to hollow the body to make room for servo's, batteries etc plus cut out control surfaces. In the end you'd be ruining a very nice model  Big grin

I had a simple RC trainer - first flight it hit a tree in straight level flight, second flight it made a hard landing, third flight was cancelled. It is harder than it looks lol


User currently offlineCanadianNorth From Canada, joined Aug 2002, 3389 posts, RR: 9
Reply 5, posted (10 years 1 month 2 weeks 6 hours ago) and read 9724 times:

Sounds like something I would do...



CanadianNorth



What could possibly go wrong?
User currently offlineVSXA380X800 From United Kingdom, joined May 2004, 421 posts, RR: 1
Reply 6, posted (10 years 1 month 2 weeks 2 hours ago) and read 9720 times:

I found some Ducted Fan motors that produces 0.90 killos of thrust(2 Pounds), each. Thats 0.90x4= 3.6 killos of thrust(8 pounds). That is also 2 more pounds than the wieght of the aircraft. Is that good enough or do I need more thrust ?

BTW what is the formual the aircraft manufactors use to figure out how much thrust they need to power the aircraft ?



4 decks 4 engines 4 long haul
User currently offlineSplitzer From United Kingdom, joined Feb 2004, 151 posts, RR: 0
Reply 7, posted (10 years 1 month 1 week 6 days 22 hours ago) and read 9717 times:

That would be more than enough thrust, even excessive (if you can ever have to much thrust!) Since the thrust to weight ratio exceeds 1:1, your model would be able to climb vertically.

This site may be of some use:

http://www.grc.nasa.gov/WWW/K-12/airplane/index.html


User currently offlineDoug_or From United States of America, joined Mar 2000, 3404 posts, RR: 3
Reply 8, posted (10 years 1 month 1 week 6 days 18 hours ago) and read 9701 times:

don't forget weight of equipment. batteries to power electric r/c aircraft can easily equal the structural weight. In addition you may need reinforcement, especaly around the batteries and wing root.


Regarding the wing, I was more intereested in what type of airfoil it appeared to have. A precise model of an airbus would have a very thin semi syemtrical airfoil, which would be a problem. You'd probably want a thicker clark y type airfoil (flat bottom). Also, what is the total wing area? as a general rule of thumb, the wing loading should be around 15 oz/ sq ft for a trainer and 22 for a hot rod I believe. thyou might want to be significantly lower than that, though, since you don't know how much lift your airfoil will produce.


Bottom line is most R/C airliner models made by non pros will be purpose built to save weight, have enlarged wings with decreased sweep to improve handling, and larger than scale engine pods to facilitate bigger blades (to accelerate more volume of air). No offense or anything, but I'm not betting in your favor. If you do have the spare $ and time to go thorugh with it, I'd strongly recommend you go for the A319 or 340-500 as they'll have larger wings compared to the fues. And if you do go ahead with it, do EVERYTHING you can to reduce weight.



When in doubt, one B pump off
User currently offlineVSXA380X800 From United Kingdom, joined May 2004, 421 posts, RR: 1
Reply 9, posted (10 years 1 month 1 week 6 days 16 hours ago) and read 9694 times:

Also, what is the total wing area?
it has an Area of 276 inches

I'd strongly recommend you go for the A319 or 340-500

Wouldn't the cargo hold be smaller in volume (1:50 even though that's big) than the 340-600 and wouldn't the 340 be able to hold most of the equipment, despite the wing area and lift produced? Besides the A380Thats the biggest model I have( that I don't mind damaging for a good cause)

I was more interested in what type of airfoil

The aircraft is made of Resin and Fiber Glass. I'm not sure if the wing is fiber Glass or Resin, vice versa with the fuselage

No offense or anything, but I'm not betting in your favor

None taken! Big grin



4 decks 4 engines 4 long haul
User currently offlineZrb2 From United States of America, joined May 2000, 896 posts, RR: 0
Reply 10, posted (10 years 1 month 1 week 6 days 16 hours ago) and read 9689 times:

I agree with one of the other posters. If your model looks like the pic you provided.....don't bother ruining it. You are surely going to crash the thing. Even if you add servos and balance it the odds are stacked against you// I speak from experience.

User currently offlineDoug_or From United States of America, joined Mar 2000, 3404 posts, RR: 3
Reply 11, posted (10 years 1 month 1 week 6 days 13 hours ago) and read 9679 times:

when I say airfoil, I mean just that. Not material the wing is made out of. the shape of the cross section of the wing.

with just under 2 sq feet of wing area, assuming you have a good airfoil, you need to keep the weight under 38 oz (3 lbs) to maintain an already hefty 20 oz/sq ft wing loading. With equipment that means you'll need to get the structure under 1.5 lbs. 1/4 of its current weight. and you shouldn't worry about the interior area of the fues. all the equipment should fit, since you'll need small (light) stuff.

Once agian, don't mean to rain on your parade, but I sincerely doubt this will be possible. If it does fly, it won't be enjoyable. it will be all you can do just to keep it in the air, and landing will be exceptionaly difficult, especialy with those wing mounted engines. and don't even say retracts. just don't even go there.



When in doubt, one B pump off
User currently offlineDoug_or From United States of America, joined Mar 2000, 3404 posts, RR: 3
Reply 12, posted (10 years 1 month 1 week 6 days 12 hours ago) and read 9674 times:

heres some ideas

http://www.rcgroups.com/links/index.php?id=3966



When in doubt, one B pump off
User currently offlineVSXA380X800 From United Kingdom, joined May 2004, 421 posts, RR: 1
Reply 13, posted (10 years 1 month 1 week 5 days 17 hours ago) and read 9642 times:

Thanks for the link,It will surely help me.

Now I know I'm not the only crazy one. When you said that this wasn't going to work Doug_or, was it because if the model and size I chose? The person who did what I am now had a good flight( except it took him 20 yards to take off) and landing was also a breeze. I know I might not have the same results because his was a 2 engine model and mine is a 4. I might have better results( in a way) because my motors will produce more thrust than his did and with the additional weight, it still might perform just as good. My model is signifactly smaller than his.

His Wingspan-67.5 In / Mine 47 In
His Length-67.0 In / 58 In
His Motor (x2) 480 BB 7.2v/ Mine (x4) 500-600 BB 11.5 v


Thanks for you help and suggestions.

BTW-The shape of the cross section of the wing is just like the real thing, same angle of attack. The only thing That I won't have control over is the Spoilers and Flaps.

[Edited 2004-07-23 20:23:17]


4 decks 4 engines 4 long haul
User currently offlineDoug_or From United States of America, joined Mar 2000, 3404 posts, RR: 3
Reply 14, posted (10 years 1 month 1 week 5 days 14 hours ago) and read 9636 times:

The point was he scratch built an airplane to fly. It was light, it had much more dihedral, reinforement in key areas, and a good airfoil. His wing loading was marginal on an aircraft much larger. Having a similar wing loading on a smaller aircraft will make it much more difficult to control. I would also advice you agianst landing gear, though I'm not sure how to propperly brace the engine naceles for impact.

RE: the wing- AOA is the angle of the wing to the relative wind (direction of flight), which varies with speed. What I beleive you are referring to is the angle of incidence (the angle of the wing to the body). When I talk about the shape of the airfoil,I'm referring to the SHAPE of the x-section of the wing. airbus aircraft usualy have a fairly thin airfoil, which has been optimized for effienct cruising around .8 mach. These things do not scale. The most effective airfoil for you application will likey be much thicker (to get more lift from the available area).

While his airplane flew, and he said he wasn't very expereinced, you have to understand a few things. Hes writing an article for poeple who know much more thna he does, so he is most likely being somewhat humble. I'm almost sure hes has done previous scatchbuilt projects. I know you said you have flown an R/C aircraft, but from this conversation, I do not believe you would have been able to handle his model (a big interpolation, I know), and you have essentialy zero experience with aircraft design.

But the bottom line is that what you are proposing is a brick with wing-like protrusions. And in my experience, those don't usually fly. There is no way you'll be able to get you model to a weight where those wings will provide adequete lift at a sane speed.


Now with that said, you learn from experience, and a few failed projects will eventauly lead to success (if you have the time, money and interest). I just don't think a project that is so inevitably doomed is really the best way to start. While its uglier, you will have much better luck starting out with a big foam glider you might find at a toy or drug store (I've seen these convereted to prop and fan r/c aircraft). It will also be much better at remaining in one piece while you are learning to fly it.

[Edited 2004-07-23 23:34:22]


When in doubt, one B pump off
User currently offlineVSXA380X800 From United Kingdom, joined May 2004, 421 posts, RR: 1
Reply 15, posted (10 years 1 month 1 week 4 days 14 hours ago) and read 9616 times:

I want to thank everyone for their help once again, I hope I get my model aircraft up and flying in the near future.


4 decks 4 engines 4 long haul
Top Of Page
Forum Index

Reply To This Topic Model Commercial RC Aircraft
Username:
No username? Sign up now!
Password: 


Forgot Password? Be reminded.
Remember me on this computer (uses cookies)
  • Aviation hobby related posts only.
  • Back all your opinions with facts.
  • No adverts of any kind. This includes web pages.
  • No hostile language or criticizing of others.
  • Do not post copyright protected material.
  • Use relevant and describing topics.
  • Check if your post already been discussed.
  • Check your spelling!
  • DETAILED RULES
Add Images Add SmiliesPosting Help

Please check your spelling (press "Check Spelling" above)


Similar topics:More similar topics...
Big RC Aircraft posted Sat Jan 24 2004 04:17:21 by Wally
Jet Engines For RC Aircraft? posted Wed Jan 2 2002 03:35:50 by VirginFlyer
How Do I Make Traffic On FS04 Commercial Aircraft? posted Sun Mar 19 2006 21:24:05 by BradWray
How To Take Off In A Commercial Aircraft posted Mon Oct 17 2005 06:12:57 by Gregjet
Best Scale For Model Aircraft posted Tue Oct 4 2005 00:38:40 by Braniff1968
Aircraft Model Shops Near LHR posted Tue Aug 30 2005 00:13:48 by 767ER
Displaying Travel Agent Size Model Aircraft posted Sat Apr 23 2005 21:55:06 by Airways45
Who Builds Model Aircraft? posted Sun Feb 13 2005 19:05:41 by Burnsie28
Very Large B747 Or Concorde Model/RC posted Mon Feb 7 2005 20:58:51 by JAM747
Anyone Here Into R/C Model Aircraft? posted Tue Jan 4 2005 00:00:27 by 22right

Sponsor Message:
Printer friendly format