Cox PeeWee Micro Speeder

balogh wrote:You have completed it very well and it flew beautifully...what happened with the fuselage, was it broken on landing? If the battery is not fixed and the landing is hard, the battery goes like a loose cannon and may destroy the bulkheads and the entire fuselage...

Thanks
No, I'm not sure if the model undercut (is that how you say it in English?) or if I was just too slow to react. It went pretty quickly into the ground, but is repaired and flown again.

At less than 100 grams it is very light and must glide very well, so I do not think it stalled. I did not see the end of the flight, but if you land in headwind with some "up" elevator, then it should not land diving head-on into the ground..

balogh wrote:At less than 100 grams it is very light and must glide very well, so I do not think it stalled. I did not see the end of the flight, but if you land in headwind with some "up" elevator, then it should not land diving head-on into the ground..

By undercutting I mean when the wing creates downforce instead of lift at high speeds. so not when landing. Unfortunately, I don't know the English term for this.

In tail wind or at too low speed the lifting force on the wing is reduced. The uplift will not be sufficient to keep the plane gliding.. This is called stalling..

Congratulations on getting some flying fun in!  

Is the vid showing the plane flying with a Cox 4Dx2.5P prop?
What is the wing span and size battery are you using?

To help avoid tucking / diving with your current sheet wing there are some options.
- shim the wings leading edge up at the wing saddle to induce positive incidence.
- move the wing forward to increase tail moment distance and reset CG.
- set up for a slight forward CG to improve horizontal stabs elevator + pressure influence on the wing.

For sheet wings I always set up with a semi symmetrical airfoil that graduates to a fully symmetrical at the wing tips.
Incorporate washout at the wings trailing edge sanding it in to improve stability further and low air speed control.  

It seem to fly pretty well , was that the maiden flight ? 1/2A Nut knows his stuff when it comes to speed , he has done a lot of it in builds and videos . Good to see you were able to fix back quickly hopefully you can get the glitch fixed for many more flights

1/2A Nut wrote:Congratulations on getting some flying fun in!  

Is the vid showing the plane flying with a Cox 4Dx2.5P prop?
What is the wing span and size battery are you using?

To help avoid tucking / diving with your current sheet wing there are some options.
- shim the wings leading edge up at the wing saddle to induce positive incidence.
- move the wing forward to increase tail moment distance and reset CG.
- set up for a slight forward CG to improve horizontal stabs elevator + pressure influence on the wing.

For sheet wings I always set up with a semi symmetrical airfoil that graduates to a fully symmetrical at the wing tips.
Incorporate washout at the wings trailing edge sanding it in to improve stability further and low air speed control.  

Thank you!
yes, its a 4Dx2.5P prop. I use a 1s 260 mAh LiPo and the wing span is 57cm.
I had no more problems on the last flights. I think it was just me.
But I've also thought about the angle of incident.
Thanks for the tips, I will implement them when building the next model!
I try to record a video with better quality and speed on wednesday.

Great to hear you can get some HD vid


I use SIG airfoil shaped balsa wood planks and modify from there.





Note the sanded airfoil wing tip has washout incorporated.

Cool this Litle plane Is that it's just me that this model reminds of the gupy The fuselage in particular

davidll1984 wrote:Cool this Litle plane  Is that it's just me that this model reminds of the gupy The fuselage in particular

I took a quick look, you're right.
Didn't know the model before and just used the form from the forum. But it's practical to fit everything in the narrow fuselage.

Any word on getting a HD vid?  


Here is one of my .020 planes.



Cox TD .020 / 3.37x4.5 Prop / bull nose prop tips.
Needed back cut on the prop blades to increase rpm with
more tapper prop tips and increased dia. to 3.5 x 4.5N  
3ch throttle sleeve, 4.2oz RTF / 19.5" Span / 43 sq. in.
Plywood fuselage with spruce stringers in the corners.
Has taken full throttle hits into the ground no breakage.


 

1/2A Nut wrote:Any word on getting a HD vid?  


Here is one of my .020 planes.



Cox TD .020 / 3.37x4.5 Prop / bull nose prop tips.
Needed back cut on the prop blades to increase rpm with
more tapper prop tips and increased dia. to 3.5 x 4.5N  
3ch throttle sleeve, 4.2oz RTF / 19.5" Span / 43 sq. in.
Plywood fuselage with spruce stringers in the corners.
Has taken full throttle hits into the ground no breakage.


 

It was too windy on Wednesday, but today was good. Here is a video with better qualtiy.


Plus one from a Delta with .049 Graffiti Bee.

This is the first time i se one of those graffiti bee runing sound Good near the tee dee rpm sound

Thank you for sharing, the engine was running a bit better up to 19.3k rpm observed  
Very good glide with the all metal weight of the Pee Wee.  
4x2.5 prop / 16,876 rpm at launch / 3.17oz thrust / 16w / 40mph prop pitch speed


I have an example with a TD 020 it uses the same Cox 4D x 2.5P prop.
Static 17,603 rpm / Best pass unloaded 25,579 rpm / 61 mph prop pitch speed



Jul 12, 2014
Cox TD .020 / 3ch Lil Speedy 1 / Cox 4x2.5 Prop
25% nitro / 21in. span with exhaust throttle sleeve
Plywood rolled fuselage, balsa foiled wings.

1/2A Nut wrote:Thank you for sharing, the engine was running a bit better up to 19.3k rpm observed  
Very good glide with the all metal weight of the Pee Wee.  
4x2.5 prop / 16,876 rpm at launch / 3.17oz thrust / 16w / 40mph prop pitch speed


I have an example with a TD 020 it uses the same Cox 4D x 2.5P prop.
Static 17,603 rpm / Best pass unloaded 25,579 rpm / 61 mph prop pitch speed



Jul 12, 2014
Cox TD .020 / 3ch Lil Speedy 1 / Cox 4x2.5 Prop
25% nitro / 21in. span with exhaust throttle sleeve
Plywood rolled fuselage, balsa foiled wings.

Thanks!
what kind of propeller would you recommend me? Something like an APC?
At a certain point the engine just won't rev up any further.

I have two Tee-Dee's .020 and one .010 in the original box. I'm tempted to try one, but they're too good for me.
Although they are made to be used.

To gain same prop rpm,
-Seal the NV with fuel tubing to hold a steady peak
-Smaller sleek plane effort, enough for a safe fast landing no more
-If with a PeeWee best with a remote 1/2oz tank and horse shoe backplate.
-Higher nitro
-Turbo plug adapter from Kamtechnik.com

The plane design was meant for performance, your choice of wingspan at 47cm / 22.44in is big for all out speed with a PeeWee.
The spans lift allows trick flying with some speed at 3.2oz RTF. Given the wings performance envelope prop choice can vary.

Prop mass, design, drag and stiffness control what's possible. The stock cox props at 2P and 2.5P limit top end speed to save
enough engine power set aside for thrust. Must consider total load on the engine counting the plane design for best prop match.  

To gain a good leap past old school speed performance the prop choice must start with at least a 3P.
To get there a 3.75x3 stock E prop works well found as a replacement prop for the Stryker.

E-Flite EFLUP037503 Prop/Propeller 3.75 x 3: Ultra Micro F-27Q Stryker


The strength is enough to spring start and fly with care no mods needed as is.
Big thrust gain due to prop design allowing increased rpm and more speed.
I have hit 92 mph pitch speed with a TD .020:

First test vid with the 3.75x3 prop

Lil Speedy II / TD .020 / 29,554 RPM / 84 MPH / Throttle Sleeve

-----

Best possible props always require modification to get top end speed or max thrust.  
I have tested the HQ 4x4.5 carbon blend prop stock and modified with good results.
Flight tested strong enough as a stock prop up to TD.051 to 33.1k - / Fuji .05 to 36.4k rpm

Another prop with a mix of speed and thrust.
APC 4x3.3E prop nice low weight and no bulky type fuel engine blades.
Stronger design stiffer blades but require modified blades to work with a .020 engine.  
Requires back cut of the blades to reduce load. For more top end rpm reduced to 3.6 x 3.3N
3.6 x 3.3N / TD .020 / 22,300 rpm static / 4.6oz thrust / 39w / 70 mph prop pitch speed / unload est. 95PS

Below the blade has some back cut but could do with further modifications per yellow lines to improve speed.



The IC APC 4.2x2 is way too beefy -heavy / over kill for a .020 and requires mod to gain rpm / speed.



Bench tested - TD .020 / OS RP4 Turbo Plug
Peak 22,206 rpm 42 mph prop pitch speed - per prop calc 6.7oz thrust / 37w
The blade was modified to keep the diameter for higher thrust gain thru added rpm.

 

there is a new video on youtube!
With Graupner 4*3 propeller, so the peewee runs very well!
https://m.youtube.com/watch?v=7OquwWCWzHo

Great flight!

Fantastic fun, fast for a Pee Wee engine / great flying the wee plane.
Perhaps a 4x3 to 4x3N and some fuel tube to seal the needle valve.
How much nitro%?

1/2A Nut wrote:


Fantastic fun, fast for a Pee Wee engine / great flying the wee plane.
Perhaps a 4x3 to 4x3N and some fuel tube to seal the needle valve.
How much nitro%?

its a ton of fun!
i mixed new fuel, 30% nitro, 2% rizinus, 18% sintetic oil and 50% methanol

2% of castor (ricinus) is very low for a COX engine, esoecially if the nitro us 30%, you better up the castor to at least half of the total oil content. The balljoint on the conrod top end needs castor.

I've now tried the TeeDee. The fuselage is a bit small in the front, so the engine had to be on it diagonally.
I don't think he did too bad! But now it's time for a new model with new improvements. Does anyone maybe even have a dfx file for a model?




https://m.youtube.com/watch?v=_YWpYkYgMXk

That was a good build log.
It flies real fast.
Should be called Ding Bat!!!
Congratulations on a great little model and also your flying skills.
At that speed you cannot afford to get disorientated.
The engine was nice as well. ( the full monte )