lvspark

I don't know if this plane is fast enough to be in this section, but I am trying to get it to go faster. It is all coroplast, with HDPE for the engine mount, and no internal structure for the airfoil. It was a very quick and cheap build.

In the pic below, it had a .25 with an 8x6 MAS and flew great. I taped my gps to it and it recorded 79mph top speed with the .25

Then I put an old royal .40 on it with a 9x8 APC and it flew much faster but the engine is very old. I flew it without a muffler, or tank pressure, because the muffler threads are stripped out. The video link below is with the .40 royal.

What would be a good, somewhat economical engine that you would suggest I purchase for it. I have just had regular engines, and his is my first speed plane and I would like it to go very fast hehe.

Also, any guesses on the speed that it was going on the video?



1 meg video with a .40

Rudeboy

I doubt you will get that thing to go "very fast"... It will move with enough engine up front, but no extremes...

That's a lot of plane you have there (or a VERY small child )... and by the looks of it, a big fat airfoil... probably flat bottom and round at the top... right? So it will always try to climb if you make it go fast... Or is it airfoiled on both sides?

Also, with no internal structure, there's no telling how it will react when submitted to high speeds, but don't expect anything good...

Hard to tell what the speed is in the video... all you see is a plane and blue sky... no reference point...

lvspark

The plane is 40"span, 26" from nose to elevon and weighs just over 3 lbs. The airfoil is not thick, just thicker than a standard servo laying on its side. The servo arm barely clears the top surface on the inside. The bottom is pretty flat, but has somewhat of an airfoil. It wasn't hard to trim for level flight at what I would guess, 100+mph and actually handled very sweet.

I would like to find out what will happen when this airframe is subjected to some serious speed. Yea, it might get ugly, but I am sure it would be fun to find out!

There are some trees and ground 15 sec into the video. Not the best video, but the camera guy was having a hard time tracking it.

Still looking for engine suggestions to find the limit of this $5 airframe.

I saw cliff with his new magnum last week, and now,,,,,,, well, you know the rest of the story, i might be hooked!

This is an exaggerated view of the airfoil. Like I say, not this curvey, but has that kind of lines.

Rudeboy

Well, you could start by asking "Cliff" if you could borrow his engine to try it on your delta...

If the airfoil is no thicker than a servo, I guess some speed won't present excessive lift problems... it just looks thicker in the picture..

I'd say try any fast .46 to .61 sized engine for some fun... if it doesn't start to act funny on these engines... step up to something even bigger...

Razor-RCU

My Feedback: (50)

Rudeboy knows whats up-

I love that you are going for it and are not real attached to the airframe ($5 ?)

Royal engines use to be pretty sweet-

If I had around:

$75- bucks= TT Pro-46/ Tower Pipe ($13-)

$100-$115 bucks= Irvine-53 or OS-46FX (again Tower muff. $13-)

$130- $140 bucks= Rossi-45, or MVVS-49 (rpm's)

$140+ YS-45, Rossi-53, or Jett-50

No matter what, keep us posted and good luck!

james

lvspark

Update:

Well, I have not changed the engine yet, but man is this thing a blast! Now I have an Idea why you guys are into speed planes!!!!
I can only fly it about 6 minutes or so untill my nerves are making me shake so much, and I have to land. A Total Rush!
The thing goes by so fast, I feel like diving for cover myself!

Fun, exciting, and scary all at the same time

As rudeboy anticipated, there is a tendency to to rise while at speed, but it does trim out. With the loss of reflex on the elevons (due to trimming), it becomes more pitch sensitive (not to bad, but noticeable) and there is an increase in speed.

I had to cut my vertical surfaces down because I used 2mm coro for weight and drag, but being lightweight, is is not so rigid, and I was getting some flutter. It now can do full speed dives without flutter, but if put into a power on stall or a rolling stall, it falls into a flat spin and lands like a heli.

If I build another, I will keep the verical surface of the origional, but use 4mm coro with some bamboo skwers in the flutes.

$5 for the airframe was an under estimate, a 4x8 sheet of coro is around $12 (2 airframes) and the HDPE cuttingboard for eng mount is about $7 ( 6-8 mounts) so $6 of coro and $1.25 eng mount. A $7.25 airframe.


I will keep an eye out for a cheapo engine, and really wring this airframe out.