|May 30, 2005, 05:08 PM|
Building a 51'' Depron Spitfire MKIX
Based on the magnificent plan available in this thread:
One Excellent S600 Spitfire Plan!!
i've decided to build my own 1/9 scale Spitfire MKIX.
There is one new Graupner 600 lying in my desk which could fit in this plane.
Yes yes yes ... I know... Brushless Rulezzzz. Maybe later, ok ?
I want to enter to the Guinness Book like the "Portuguese guy who has built the least expensive RC Spitfire of all"
The original plan was intended for balsa use. I am going to build mine, using 5mm Depron all over.
I have lots of experience because i have already built one (yes one) Depron plane: the F/A-18 Hornet Park Flyer.
(you can find it here - My first F-18 !)
Only one plane ?!?!?! Well, maybe i'm not an expert... That's why i hope to get some help from you guys !
Oh, by the way, i've only started flying last December... But i read a lot of RC magazines, surf a lot in the Internet and practice a lot in the flying field !
Well, enough talk, lets start !
PS: I don't know what to love more: Building or Flying...
|May 30, 2005, 05:17 PM|
Wing construction 1
These are my first pictures of the bottom wing. 4 hours working.
I've used UHU Por, hot melting glue and CA foam safe.
|May 30, 2005, 05:34 PM|
Wing construction 2
The glue in the ribbs is cured and both spars have been fixed. The aillerons hinging zone is reinforced.
|May 30, 2005, 05:41 PM|
Wing construction 3
The two bottom wings are ready. Next i have to cut the holes for landing gear and ailleron servos.
|May 30, 2005, 05:53 PM|
Ok... Now i have to make a decision and need expert advice.
My radio has only 4 channels:
1 - Throttle
2 - Aillerons
3 - Elevator
4 - Rudder
I want to have landing gear.
I don't think this plane will look good in the air with the hanging donnuts !
That's why i would love to use a retract landing gear my own design, but this way, i have to eliminate rudder.
Can this plane fly well without rudder control ? I don't have rudder in my F-18 and it flies very well !
Help please !
PS: Buying another radio isn't an option, ok ?
|May 30, 2005, 07:03 PM|
Models that fly well without rudder control usually have more dihedral in the wings than models that fly with rudder, aileron, and elevator control.
If you don't want to change the plan and put more dihedral in the wings, you can still use the rudder *and* still have a retract channel.
Use a Y connector to join the aileron servo with the rudder servo. If you are using two aileron servos, pick one and join the rudder to that one. When your stick in-put makes the ailerons move, the rudder will follow along with them.
Use the mechanical linkage to make the rudder deflect pretty much the same angle as the aileron.
You may have to fiddle with it, but this can be made to work quite well. I did this on a JK Aerotech T-52, when I added ailerons to it.
Not exactly "full-house" control, but not bad. This will allow turns without adverse yaw and your rolls should be much smoother, too.
I got this from the 1st US R/C Flight School's Primary Flight Training Manual. Great book, it did a lot to help me learn to fly without an instructor. (Not the best way, but it was mine.) They also have a video that goes with the book that is simply fantastic.
Their book does a much better job of explaining the above and they do have sample pages on their web site. It just so happens that the pages that you need *are* on-line.
Take a look at these two pages, they may help. Here they are:
ONE. This one explains the "why" of it.
TWO. This one shows the "How."
Hope this helps!
|May 30, 2005, 07:10 PM|
flying without rudder won't be a problem, but most (if not all) tail draggers need rudder to keep them straight during take off. How about hand launching and using the wheels for landings only?
Don't think you need more dihedral without rudder. It's the other way around, more dihedral needed without ailerons.
|May 31, 2005, 01:22 AM|
This is great!! I have some plans laying around that I would like to build using the same materials as you, so I will be following the build for advice.
Do you need carbon or balsa wing spars or is the foam enough?
|May 31, 2005, 02:33 AM|
I hope you get this one flying I have been watching the other thread since it started I do not remember anyone flying it yet! Hul is correct, more dihedral is needed for rudder only.
|May 31, 2005, 10:08 AM|
Yes, it is R/E models that require a certain amount of dihedral. But A/E and even A/R/E controlled models can benefit from a small amount of dihedral, in that it gives the model a certain amount of roll stability.
Too much, it will fly like a trainer. Or worse, it will be very hard to turn. But when you get just the right amount, it makse for a nice, stable aircraft that doesn't require constant control inputs for straight & level flight.
When I did my aileron conversion on the T-52, I found the "magic numbers" to be one-half the dihedral that it had for R/E operation. Hands-off, it would track straight and true. Give it a little aileron to put it in a bank, the model would roll and hold the bank, even when you returned the stick to center, but then it would slowly return to level flight.
What I was looking for was a full, 3 axis control model, but one that didn't require constant control inputs just to maintain straight and level flight. A small amount of dihedral gave that to me.
Anyway, it worked for me.
|May 31, 2005, 12:47 PM|
I'm still in the beggining of construction and i can not tell you if i'm going to use or not other materials then Depron.
For the wing, i've only used Depron and i'm satisfied with the strenght of it.
But i have some carbon spars and balsa ready to use if necessary.
If i have to use a long square balsa strip, i prefer to do it, using two pieces of Depron glued together. It's lighter then balsa.
For the wing leading edge, probably, i will use balsa. It's more resistant to dinging (is this the right word ? )...
|May 31, 2005, 12:52 PM|
I have a problem: Until de day of maiden flight, i sleep very very bad !
I just keep thinking about the flight, construction problems, finishing de plane, etc etc...
Don't know if i am the only one with this problem...
That's why i HAVE TO FLY THIS ONE !!!!
Don't worry, i will fly it !
|May 31, 2005, 12:55 PM|
Hi Mad Mike,
Thanks for your advice. I'm going to think about it.
Let me know one thing: Like "hul" says, the rudder is necessary for the take-off. Does your method resolve this problem ?
I have already seen in a magazine, a test to Ripmax Spitfire, and the author decided not to use rudder control. The model flight was very good, but he hand launched de plane. And the landing was on his belly...
I have to make a decision. And i think it will be: Ailleron, Elevator, Throttle and... Rudder control with fixed undercarriage.
It doesn't look so bad, does it ?
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