looking for a phoenix 8
 

I flew one of these when i was a kid for about 15 years it had a OS 61 fx heli motor with tune pipe on it. It was a blast but my old man sold it 5 years ago since i wasnt flying it any more. Also ive check with aztec he's out of country is there any one else with kits. i really want another one to biuld as a electric i want to push it past 200 mph.

RE: looking for a phoenix 8
 

WHAT ??? 200 mph, electric ? Here is one from my hangar, what's the plan ? Why doe's it have to be the 8 ?

Crank

RE: looking for a phoenix 8
 

i found a maker of the kit. but im planning for motor is a Neu 1512-2Y 770 KV, 100Amp esc 6 cell 5Ah lipo with that system it should spin a 11x10 at 18K rpm the head of the engine is gone and pipe so you loose all the drag and the 61 glow at best was only 1100 watts to the prop and the motor is peak 3000 watts that is going in it. also plan to gear door the nose and mains. also will make glass hinge gap covers the P-8 is so clean and stable that with a few mods it will out run some of those turbines. only plane i have now flyable is my f9f with a kj-66

RE: looking for a phoenix 8
 

Take a look at the P-7, no chin on the nose, unless you need that room.

Crank

RE: looking for a phoenix 8
 

That airfoil is never going 200 mph. Especially with open wheel wells on the typical retracts. Try an old Formula 1 kit instead. Thin airfoil and streamlined gear.
Chris...

RE: looking for a phoenix 8
 

True. The Phoenix 8 or 7 airfoil is much too thick to hit 200mph.

RE: looking for a phoenix 8
 

A stretched Norm Page Mach One may help, but this is not practical. Wagner, what is your budget for this project ?

Crank

RE: looking for a phoenix 8
 

the one i flew not that many years ago would do 170mph with a 60 heli engine. 200 isnt that much faster

RE: looking for a phoenix 8
 

Hallo Wagner24314

Did you measure that 170 mph, and if yes, how?
With that you can estimate the power needed for 200 mph

Cees

RE: looking for a phoenix 8
 

radar gun both way up wind and down

RE: looking for a phoenix 8
 

What would be the needed "more" power 170 mph to 200 mph? Ratio?

Cees

RE: looking for a phoenix 8
 

im starting with a neu motor that will turn a 11X10 at 17000 rpm the .60 would only turn a 11x7 at 15500 rpm on a good day

drag of head and pipe will be gone the motor will have easy twice the Hp

RE: looking for a phoenix 8
 

At least 40% more.  However, I have my doubts about 170 mph.  I think 110 to 120 is more realistic.


Rob</p>

RE: looking for a phoenix 8
 

Rob,

That was my thinking too, 38 % more, but 11 x 10 and 17000 is probably 259 km/h max is 161 mph (100 % prop efficiency!!)
I will do a double check!

edit, I did check my calculation, correct.
Prop eff never can be 100 % so Rob's values are more realistic.

Anybody else?


Cees

RE: looking for a phoenix 8
 

Wagner24314

When our calculations are correct, we need at least about 54 % more power, (from 161 to 200), to reach 200 mph, can you make that?
The prop must have an efficiency of 100 % than!

Cees

RE: looking for a phoenix 8
 

yea we are good

RE: looking for a phoenix 8
 

I just did a quick back-of-the envelope calculation:

Thrust = Drag

Drag = 1/2(rho)V**2SCd - Fortran notation used to denote velocity squared

I assumed air density (rho), surface area (S), and Drag Coefficient (Cd) as constants and arrived at a ratio of (200 mph) squared divided by (170 mph) squared

I also assumed prop efficiency as a constant (probably not the case) and power to thrust curve is linear (a simplification) and came out with 1.38 as the ratio.  Simplified, but a starting point.


Rob

RE: looking for a phoenix 8
 

Wagner,

The Phoenix 7 suggestion is a good one.  The airframe is readily available and is very well engineered.  You use a P-7 ARF as a proof-of-concept plane and see how it works out before installing it in a hard-to-find classic.

I am curious if you can hit 200,  Also, I did a quick check of your power numbers.  You might need a bigger ESC.  To get 3000 watts on 6S, you'll be pulling over 120 amps.  That assumes full charge and no voltage drpression from the load.

When you fly the E-Phoenix, please post the results.


Rob

RE: looking for a phoenix 8
 

Rob,

You are correct,.

When I calculate the needed power it is 220 % more than the moter 11X10 at 17000 of this moment. ( with 70 % efficiency of the prop).
All fast calculations!

Cees

RE: looking for a phoenix 8
 

P-8’s are not hard to find, New glass parts are readily available.


I’ll be watching this thread with interest.

Like to see 200mph out of a P-8, and e-power to boot!

RE: looking for a phoenix 8
 

Maybe the 170 mph was actually 170 kph... easy for the gun to just have been in metric mode.

What about reducing the airfoil thickness in the P7/P8 rather than going to an F1 design. Going with a P8 might actually make this easier to accomplish since the cores could be cut fresh. On the other hand a P7 fuse/tail kit could be bought and a new wing made. I would want a foam core wing if aiming to hit 200 mph - that's some serious speed. Full carbon veil treatment and heck, maybe even some square CF spars lining the sides of the retract wells. Full covers and paint of course.

What kind of C rating discharge are we talking about? I know there's a guy who setup a GP revolver (I believe) with 10s. It weighed a ton (10-11 lbs I think) but it moved out in a serious way. Unlimited vertical was an understatement - it just vanished. That guy had really good eyes (or perhaps the eye in hid mind).

Cool,

its been a while since I read anyone making an equation post using Fortran notation. I might have used v^2 notation. Actually this notation is something that applications such as Firefox understand. Ever try punching in 10^2 in the FF Google field? All kind of conversions can be done.

David.

RE: looking for a phoenix 8
 

where do you get those tires?

RE: looking for a phoenix 8
 

Rob,

Back in the seventies Dr. Maynard Hill set a speed record while <span style="font-size: larger"><span style="font-family: Arial">working </span></span>at John Hopkins Applied Physics Lab. If memory serves me the speed record was in the 180s (believe MPH). Doing some searching I noticed an article referencing Dr.Hill on wattflyer, progressiveengineer, and RCU: <span class="f"><cite><font color="#0e774a">www.rcuniverse.com/forum/fb.asp?m=2214160</font></cite><font color="#767676"> (cached). </font><span style="font-size: larger">Remembering the story from then he made many attempts at getting the aircraft correct and the engine properly setup (glow, 10cc) and eventually was successful at setting the record. Much could be learned from his work should this progress beyond just a discussion.

Respectfully,

Mike Plummer</span></span>

RE: looking for a phoenix 8
 

MetallicaJunkie,

You write: where do you get those tires?

We could buy these tires (wheels) in the Netherlands but that could be a VERY long time ago.
Dimensions are 73 mm 2 13/16 on it (see picture) but there is no brandname.

Reason I did show the picture was, he did write:

the one i flew not that many years ago would do 170mph with a 60 heli engine. 200 isnt that much faster
"Would"? Does that mean he didn’t measure it.

I often measure and log the real airspeed and for that I know my highest speed ever was 245 km/h (152 mph) in a vertical down line, horizontal speed 195 km/h (122 mph), pumped Webra Speed 10 ccm with Sonex pipe and own design pattern airplane. That's why I think 200 mph you will not reach with that plane, but I am curious.

Cees

RE: looking for a phoenix 8
 

remmulp ekim,

I always do put an "enter" behind such a link you did show

www.rcuniverse.com/forum/fb.asp?m=2214160


Cees

RE: looking for a phoenix 8
 

Here is a real motor. Going to set a speed record, get the AMA involved, make it official.

V

RE: looking for a phoenix 8
 

Alright,

here is the video of the GP Revolver at 160 mph - level flight. I was under the impression he had approached 200 with a 10s setup.

The thing is, the revolver is a "speed" design with a 59" span, thin airfoil and a high wing loading of up to 29 oz/sq ft. Specs call for a 55 size engine. People have put 91's in it and say they can't quite match the 10s electric setup.

I've been wondering actually whether 6s will do it (if it can be done). It seems to me that a very high kV motor (DF type) with a low drag prop on it (maybe 10" max diameter) and something more akin to 8s might be needed but I'm just speculating. Someone like Andy who is knowledgeable with electric setups might be able to better configure the e-power train but high cell count and low capacity (just to set the record) seems paramount. That wing (and stab) is also going to be crucial. The P7 should have less form drag than the Revolver.

This would be info to just start getting one's hands wet with the speed record attempt:

http://en.wikipedia.org/wiki/Parasitic_drag

That finish is going to be paramount too.

David.

RE: looking for a phoenix 8
 

So true Crank but I think e-power might be the way to achieve this if possible. The outer shell of the fuse has got to be bullet like.

David.

P.S. Finally found me a NIB OS 40 VF after a long search :D Love those engines!

RE: looking for a phoenix 8
 

David,
Check the C/L forums for VF40's. They used to be popular.
Chris...<br type="_moz"/>

RE: looking for a phoenix 8
 

Vince,

Is your Phoenix 7 from a vintage kit or is it a customized Hangar 9 ARF?  It looks awesome!


Rob

RE: looking for a phoenix 8
 

Rob - The silver and white P-7 is not mine. It was posted some time back, saved it, looking to copy what he did. I have the P-7 and P-8 kit's.

Vince

RE: looking for a phoenix 8
 

Here are some pictures of my Phoenix 8. I built this plane back in the 80's ,glassed and painted. It has s YS 60/Mac tuned pipe, spring air retracts. I have upgraded the servo's and a 2.4 JR Rx. It still flys occasionally and is very fast.

Steve

RE: looking for a phoenix 8
 

I'm not going to dispute anybody's speed claims. I just wanted to point out that the current FAI F3A (R/C) combustion engine speed record is 343.92 KM/hour or 213.702MPH. The current record for R/C electric motor propulsion is 361.00KM/hour or 224.315MPH. Breaking or even attaining 200mph is a bit more difficult than it may seem. Of course, the original motivation for this thread was just to get a 'honkin' P-8 in the air and that is definitely achievable.
One final consideration: the accuracy of radar detectors. To set an FAI approved record the speed must be timed over a specific distance in both directions (then averaged, I believe). Back in the 70's (when I was a lot younger, more energetic and very curious) I had the father of a friend (who was a police officer) provide some radar numbers on the airplane I was flying at the time; a Joy Products Mars (now called the Excalibur by Balsa USA). With the help of some friends, I then measured off 1/4 mile (1/8 mile on either side of me) and we performed some timed speed tests (this was actually a really fun physics project - fly and get credit for it :D ). Once we got the hang of the timing part of the distance test we got pretty consistent results - 10-15% slower than the radar readings. Of course this was about 35 years ago and I assume... that radar detectors have improved.
Good Luck and go fassssssst!

RE: looking for a phoenix 8
 

Danke

RE: looking for a phoenix 8
 

You may like this ones , alloy hub and not expensive really good ones.
Different size's available.
http://www.hobbycity.com/hobbycity/s...idProduct=4119

RE: looking for a phoenix 8
 

Must have been aHazzard County Sherrif's Department surplus radar gun! http://www.rcuniverse.com/forum/js/f...sn/biggrin.gif

RE: looking for a phoenix 8
 

David,
really? a 40 VF, I have one as well,, wish I would have known, its going up for sale as well,, soon ,,

RE: looking for a phoenix 8
 

If tyou are really serious, you may want to reference the current crop of Quarter 40 pylon racers, they are purpose built and are almost 200 mph airplanes, they are a LOT smaller than a pattern bird, with a LOT thinner airfoil. May give you some perspective on what is needed.

RE: looking for a phoenix 8
 

those are nice!!!

RE: looking for a phoenix 8
 

thoe chrome rims remind me of the vintage dubros ....

this thread is making want to build my Tipo.....