Joe Trinkley

I'm building a 2 pound airplane that has this motor on the front of it, I want it to go as fast as possible, what would be the best prop for me, I bought a 9x8 today but something tells me this wouldn't be the most ideal prop. Thanks

dhooks

My Feedback: (24)

That would more then likely put too much load on your engine why dont you try a 9x6 or one of the pylon props. Thats a lot of engine for a 2 lb plane, should really scoot. What plane is it?

Dan

Joe Trinkley

it's a home made plane, i attached a picture, it's the one on the left...and it ended up weighing 1.7 pounds

Joe Trinkley

someones got to have an idea

PAINLESS

My Feedback: (19)

I have used an apc 8x8 on a TT40 pro with good results.

Where is the CG on that little plane?

Joe Trinkley

i have no idea, what should it be?

PAINLESS

My Feedback: (19)

I have an Excel spead sheet that can calculate it. What is the length of the wing down the center (chord) and span?

Rudeboy

Now that looks like an interesting thing to maiden...

I'd start by launching it (almost) straight up... you have very little wing area there...

Also your vertical fin area looks to be a little on the small side. Or does it continue under the wing or something?

The next thing that looks very small are your elevons... you're going to have a difficult time landing (and launching) that thing...


Keep us posted on how this thing flies, because it looks awfully small compared to the powerplant up front...
I'm really curious as to how it will fly.

FlooredCOBRA

is there anyway you can make a video on the first flight? I made something like that a long time ago. Hopefully yours will fly better than mine did. It was an instant spin as soon as it left my hand.

If you have a good way to launch it up pretty good and then ease the throttle on it may be easier to get going.

cabanestrut2002

sorry to put a dampener on things but that plane will never fly.
(is it a joke!)

your fin is way too small to be effective and is stuck in the turbulence behind the tank and radio gear.

the centre of gravity must currently be about 3 feet in front of the plane and you are going to need about 3 lbs of lead in the back end to balance it!

with around half a square foot of wing area and 2 lbs all up weight you have a wing loading or around 64 ounces/ square foot!

nothing human could launch this plane above its stalling speed, not even a bungee.

the prop diameter is almost as much as the wingspan and so as soon as it is thrown the wing will start to spin at about 3000 rpm in the opposite direction of the propeller due to the massive torque/small wingspan/area.

as for props, try a 1" diameter x 50" pitch and you might get away with the torque reaction.

the elevons are way oversize in proportion to the wing but that doesnt matter as it will never be airborne!

put the 42gp on the quickie next to the plane in question and you will have a little ripper!

sorry if this has pissed on your fireworks but im just trying to help.
good luck anyways.

Joe Trinkley

hmmm

Joe Trinkley

going to make the fin bigger since you mentioned it though, i put this on PBF and everything went fine, how much bigger would i have to make it? think small now

astropuppy

My Feedback: (23)

Looks like a Quickee to me. Maybe a little small.


9X5 or 9X6 prop: tune for 13K plus and let it go. It will fly fine. I would suggest setting your aileron and elevator throws no more then 3/16" (each way) on low rates and maybe a little more on high for landing. You may also want to consider making sure you can kill the motor in the air. Props get mighty expensive when you break one per flight.

Have fun and let us know how it goes.

Joe Trinkley

thanks puppy, here's the new version with a bigger tail

cabanestrut2002

are you talking about the one on the right or the left.
if you are talking about the one on the left, have a hard look at the photo, look at the size of the prop and the wingspan and re-read my post a few times, you should realise it will never fly

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joe, how about building one of these, there are loads in our club and they fly so well, they are unbreakable, pretty fast and will the suit your engine perfectly


correx delta

Joe Trinkley

nice looking plane, i will look into it, still going to try to fly this one though

cabanestrut2002

the bigger tail that you have put on it will not make it fly,
what you need is more wingspan, about 30", you also need to get the wing loading down to around14 oz/sq ft

cabanestrut2002

trust me, i have seen this before , im just trying to avoid you some dissapointment. it wont fly and you could get hurt

Rudeboy

Hard to tell from that pic... give us a pic from right on top and one from the side... or some measurements (like wing area, root chord, total length...)
You could also consider two fins instead on one.

But I still say launch that thing straight up... just let go, as you have plenty of power... But like someone already pointed out: beware of a massive torque reaction... use all the throw you can get on them little elevons! They are right behind the prop, so that should help a little, but still...

And keep possible overly curious spectators away... except for someone who is keen on taking risks... have him film the flight and let us see the vid...

If you have a hard time balancing the little sucker, start by moving that huge battery all over to the rear, and maybe them servos too... Who told you to put all your stuff on the front end of the plane?
If it still doesn't balance out, try adding a small piece of a broken fishing pole on the back of the plane, in such a way it sticks out the back a few inches. You can then put weight in the end of the tube... and maybe even mount your fin on it... do you get the picture?

You definitely followed the "even a brick will fly, if you strap a big enough engine to it" line of thinking... but remember this is only a saying.
Why don't you put a nice little .10 on it and some micro radio equipment? It will still haul ***** as it will still be way over powered with the .10 (because it will be over a pound lighter)

krazy_flyr

looks like a flying motor or it will soon become one.

cabanestrut2002

Why don't you put a nice little .10 on it and some micro radio equipment
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now theres a fine idea- that would fly very well with a 7 x 7 prop or similar

cabanestrut2002

it will soon become one.
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yeah-become one with the ground!

Joe Trinkley

on the flying delta, what does it mean by "doubler underneath is 14" wide", is that a second piece of coroplast?

cabanestrut2002

yeah, the top sheet is the main wing, and underneath there is a second sheet doubler that is 14 " wide, ie- 7 " each side of a centreline

astropuppy

My Feedback: (23)

Oh, I thought you were going to strap the little (delta) one on to the Quickee. What the heck; If its the Delta (alone) we're talking about. I'd get it running; then with a running leap, throw it by a wingtip at a high angle of attack. It will straighten out and fly eventually.