[/quote]
1/4'' x 1/8'' carbon tubing
[/quote]

MattK,

Carbon tubing to replace the wire struts ? Interesting. Very light indeed.

As someone else had asked, how would you tighten down the set screws without colapsing the tubes ?

Maybe solid carbon rod instead of tubing ?

Have you got carbon tubes to work ?

Joe M

Regular steel struts are cut off leaving about 1/2 stub. Carbon tubes epoxied onto that. The rest is simple and anyone capable of tackling a P7 build can figure the rest out

I know, I know.... It's suppose to be a re-creation of a glow powered classic but I don't wanna fly a glow model. I like my new clean electric power better. With that said, here is my first attempt at sizing an electric power system for it. I think it's needs a little tweeking. I'm only getting a little over 4.5 minutes of full throttle per charge. Maybe go with a little larger prop, a little slower motor next run through the calcs. Anyone else contemplating an electric powered P7?

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Heading"></w:lsdexception></w:latentstyles></xml><![endif]><![if gte mso 10]><style type="text/css"> Style Definitions */table.MsoNormalTable{mso-style-name:"Table Normal";mso-tstyle-rowband-size:0;mso-tstyle-colband-size:0;mso-style-noshow:yes;mso-style-priority:99;mso-style-qformat:yes;mso-style-parent:"";mso-padding-alt:0in 5.4pt 0in 5.4pt;mso-para-margin-top:0in;mso-para-margin-right:0in;mso-para-margin-bottom:10.0pt;mso-para-margin-left:0in;line-height:115%;mso-pagination:widow-orphan;font-size:11.0pt;font-family:"Calibri","sans-serif";mso-ascii-font-family:Calibri;mso-ascii-theme-font:minor-latin;mso-hansi-font-family:Calibri;mso-hansi-theme-font:minor-latin;}</style><![endif]><p style="margin-bottom: 0.0001pt; line-height: normal;" class="MsoNormal"><span style="font-size: 18pt;" times="" new="" roman="" serif="">MotOpinion &ndash; Phoenix 7</span></p><p style="margin-bottom: 0.0001pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif="">800ft above Sea Level, 29.92inHg, 56&deg;F</span></p><p style="margin-bottom: 0.0001pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif=""></span></p><p style="margin: 0in 0in 0.0001pt 10pt; text-indent: -10pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif="">Motor:</span><span style="font-size: 9pt;" arial="" sans-serif=""> <b style="">Hacker B50 8S[/b]; 4613rpm/V; 3.5A no-load; 0.0056 Ohms.</span></p><p style="margin: 0in 0in 0.0001pt 10pt; text-indent: -10pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif="">Battery:</span><span style="font-size: 9pt;" arial="" sans-serif=""> Zippy Flight Max 4000 (20C) (20C); 6 cells; 4000mAh @ 3.7V; 0.008 Ohms/cell.</span></p><p style="margin: 0in 0in 0.0001pt 10pt; text-indent: -10pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif="">Speed Control:</span><span style="font-size: 9pt;" arial="" sans-serif=""> Castle Creations Phoenix 80; 0.001 Ohms; High rate.</span></p><p style="margin: 0in 0in 0.0001pt 10pt; text-indent: -10pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif="">Drive System</span><span style="font-size: 9pt;" arial="" sans-serif="">:</span><span style="font-size: 9pt;" arial="" sans-serif=""> <b style="">APC 11x7[/b]; 11x7 (Pconst=1.11; Tconst=0.95) <b style="">geared 6.7:1[/b] (Eff=95%).</span></p><p style="margin: 0in 0in 0.0001pt 10pt; text-indent: -10pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif="">Airframe:</span><span style="font-size: 9pt;" arial="" sans-serif=""> <b style="">Phoenix 7; 690sq.in; 120.4oz RTF[/b]; 25.1oz/sq.ft; Cd=0.047; Cl=0.47; Clopt=0.67; Clmax=1.24.</span></p><p style="margin: 0in 0in 0.0001pt 10pt; text-indent: -10pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif="">Stats:</span><span style="font-size: 9pt;" arial="" sans-serif=""> 147 W/lb in; 129 W/lb out; 23mph stall; 32mph opt @ 47% (40:58, 90&deg;F); 38mph level @ 53% (34:30, 94&deg;F); 1890ft/min @ 42.8&deg;; -253ft/min @ -5.2&deg;.</span></p><p style="margin-bottom: 0.0001pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif=""></span></p><p style="margin-bottom: 0.0001pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif="">Possible Power System Problems:</span></p><p style="margin-bottom: 0.0001pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif=""></span></p><p style="margin: 0in 0in 0.0001pt 10pt; text-indent: -10pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt; font-family: Symbol;"><span style="">&middot;<span style="" times="" new="" roman=""> </span></span></span><span style="font-size: 9pt;" arial="" sans-serif="">The full-throttle motor current at the best lift-to-drag ratio airspeed (57.5A) is lower than the motor's maximum efficiency current (110.1A). A higher current level would improve system efficiency.</span></p><p style="margin: 0in 0in 0.0001pt 10pt; text-indent: -10pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt; font-family: Symbol;"><span style="">&middot;<span style="" times="" new="" roman=""> </span></span></span><span style="font-size: 9pt;" arial="" sans-serif="">Current can be increased by using more cells, a larger diameter or higher pitched propeller, a lower gear ratio, or some combination of these methods. <i style="">(Yeah, but I want it to fly like a P7)[/i]</span></p><p style="margin-bottom: 0.0001pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif=""></span></p><p style="margin-bottom: 0.0001pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif="">Power System Notes:</span></p><p style="margin-bottom: 0.0001pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif=""></span></p><p style="margin: 0in 0in 0.0001pt 10pt; text-indent: -10pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt; font-family: Symbol;"><span style="">&middot;<span style="" times="" new="" roman=""> </span></span></span><span style="font-size: 9pt;" arial="" sans-serif="">The voltage (19.4V) exceeds 12V. Be sure the speed control is rated for at least the number of cells specified above.</span></p><p style="margin-bottom: 0.0001pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif=""></span></p><p style="margin-bottom: 0.0001pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif="">Possible Aerodynamic Problems:</span></p><p style="margin-bottom: 0.0001pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif=""></span></p><p style="margin: 0in 0in 0.0001pt 10pt; text-indent: -10pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt; font-family: Symbol;"><span style="">&middot;<span style="" times="" new="" roman=""> </span></span></span><span style="font-size: 9pt;" arial="" sans-serif="">The static pitch speed (87mph) is much greater than 3 times the stall speed (23mph), which might make take-off or hand launching very difficult, and is inefficient in flight unless very high speeds are intended.</span></p><p style="margin: 0in 0in 0.0001pt 10pt; text-indent: -10pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt; font-family: Symbol;"><span style="">&middot;<span style="" times="" new="" roman=""> </span></span></span><span style="font-size: 9pt;" arial="" sans-serif="">Pitch speed can be decreased by using a lower pitched and/or larger diameter propeller, a higher gear ratio, a lower cell count, or some combination of these methods. <i style="">(I believe an APC 11x7 at 13000 rpm +/- is about right.)[/i]</span></p><p style="margin-bottom: 0.0001pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif=""></span></p><p style="margin-bottom: 0.0001pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif="">Aerodynamic Notes:</span></p><p style="margin-bottom: 0.0001pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif=""></span></p><p style="margin: 0in 0in 0.0001pt 10pt; text-indent: -10pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt; font-family: Symbol;"><span style="">&middot;<span style="" times="" new="" roman=""> </span></span></span><span style="font-size: 9pt;" arial="" sans-serif="">Due to some of the potential problems listed above, this model may require an experienced pilot. <i style="">(Well duh. [/i]</span><i style=""><span style="font-size: 9pt; font-family: Wingdings;"><span style="">J</span></span>[/i]<i style=""><span style="font-size: 9pt;" arial="" sans-serif="">)</span>[/i]</p><p style="margin: 0in 0in 0.0001pt 10pt; text-indent: -10pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt; font-family: Symbol;"><span style="">&middot;<span style="" times="" new="" roman=""> </span></span></span><span style="font-size: 9pt;" arial="" sans-serif="">The static thrust (109oz) to weight (120.4oz) ratio is 0.91:1, which will result in very short take-off runs, no difficulty taking off from grass surfaces (assuming sufficiently large wheels), and steep climb-outs.</span></p><p style="margin: 0in 0in 0.0001pt 10pt; text-indent: -10pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt; font-family: Symbol;"><span style="">&middot;<span style="" times="" new="" roman=""> </span></span></span><span style="font-size: 9pt;" arial="" sans-serif="">At the best lift-to-drag ratio airspeed, the excess-thrust (80.9oz) to weight (120.4oz) ratio is 0.67:1, which will give steep climbs and excellent acceleration. This model should be able to do consecutive loops, and has sufficient in-flight thrust for almost any aerobatic maneuver.</span></p><p style="margin-bottom: 0.0001pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif=""></span></p><p style="margin-bottom: 0.0001pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif="">General Notes:</span></p><p style="margin-bottom: 0.0001pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt;" arial="" sans-serif=""></span></p><p style="margin: 0in 0in 0.0001pt 10pt; text-indent: -10pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt; font-family: Symbol;"><span style="">&middot;<span style="" times="" new="" roman=""> </span></span></span><span style="font-size: 9pt;" arial="" sans-serif="">This analysis is based on calculations that take motor heating effects into account.</span></p><p style="margin: 0in 0in 0.0001pt 10pt; text-indent: -10pt; line-height: normal;" class="MsoNormal"><span style="font-size: 9pt; font-family: Symbol;"><span style="">&middot;<span style="" times="" new="" roman=""> </span></span></span><span style="font-size: 9pt;" arial="" sans-serif="">These calculations are based on mathematical models that may not account for all limitations of the components used. Always consult the power system component manufacturers to ensure that no limits (current, rpm, etc.) are being exceeded.</span></p>

I didn't see a tuned pipe in your list......
If it can't use a tuned pipe.... wrong power plant! What next? Fixed tail dragger landing gear?

Maybe a Seniorita for your electric motor...but never a P7.

BTW... Dave Brown retracts get my vote........

Dave "old school" Rigotti

Mike Wiz,
Any picture of your electric P7?

/Bo</p>

Senroita....Really... Well to each his own.... I guess.

No pictures. I haven't got one....yet. I'm still working out the power system. I wanna make sure it will all work before I buy. I have absolutely zero interest in owning another glow model. I certainly can appreciate other people's glow models, though.

Dave, i wouldn't even put electric power on a senorita.

Don't get me started!

We have a very nice combo of a classic pattern plane, great engine and pipe combo offered too not to mention retracts to boot!

Whats next... "Where's that pound can of Pirelli?"

Dave

I'm going with glow for sure, but electric power ? Why not ? As they say.........."To each their own".

The one big problem I can see with going electric on the Phoenix is there may be no easy way to get to your lipo. Some sort of a hatch will need to be designed and fabricated.[sm=thumbs_down.gif] It sure would be a pain to have to remove the wing each time you need to change your lipo.

The one big gain would be the streamlining effect. That cowl would remain real pretty with no butchering.[sm=thumbs_up.gif]

Just my two cents.

Joe M.

Hey Dave,

Old school ? Sounds like you should also drag out that old Orbit radio and a set of 1975 Kraft linear servos. These new-fangled radios must also be a bit of a challenge for you.[X(]

Jus' kiddin'......................

Joe M.

Here's the way I solved battery access on my Phoenix 5. I built an open ended box of lite ply inside fuselage and slid battery into it through hole where nose wheel would have been and secured the open end with a velcro strap. I built the P-5 as a tail dragger.

I just blew breakfast all over my keyboard.....

I do have a working World Engines 5 channel radio on "blue and white".....

Dave "not stupid either" Rigotti

an electric tail dragger classic pattern plane? [:'(] at least i'm not eating breakfast.

Maybe the control-line guy's will comment here. Make it UC. Below is my power, plus the OS 61 SF's.

Crank, from the Phoenix Farm.

Well, that's you. Are you saying all planes should be built the way you'd build them? Is there no room for diversity in your world?
I suppose I could just knuckle under to your opinion and pop in a glow motor in my plane but why?.... to please someone on a discussion board that I've never met? I think not. I also think I'm not the lone ranger here. Other people would like to power their P7 with a modern electric power system. I'm not interested in having it be a tail dragger and I definitely want retracts. I just don't want to drag out all that old glow stuff for the one plane in my hangar that would need it.

Mike,

This is a forum of idea exchange. You should try and figure out how to do an effctive electric set-up, with retracts. I am interested in that from an academic point of view. Large props will be tricky to fit a nose gear for. I'd like to see how you do that.

That means the NG will retract half way thru the belly pan.

Crank

Not real sure what the difference is putting electric in one, with guys putting .90's in them. Neither power plant is what the plane was designed for, yet both work. I'm also sure that if electric technology then was what it is now, that many guys would've used an electric setup.

Arch

At this point it's still a study project. I'm not saying that it is doable. It may well not be but I'm going to find out. I think a geared inrunner will give me my best shot at making it work. As of yet, I've not seen one of these planes first hand. I want to be sure I can get the battery in there and still have the NG retract. I don't want a tail dragger. I basically want to preserve the entire flavor of the airframe but power it with electrons. If it's not going to work within those guidlimes then I'm not doing the project.

Heck, some of the fun in this hobby is just in the planning anyway. None the less, if it will work, I have some money set asside to make it a reality.

I think the tough part is going to be in getting a battery in a good place for balance and still have access to change it out easily and also still have the NG retract. I've already proved to myself above (with the help of Motocalc) that I can duplicate the performance with electric power and not have too big of a prop. Of course and as always, when trying to nearly exactly duplicate a glow power system with electric power there is a trade-off. In this case, the negative is duration. 4 minutes of full throttle is pretty low for today's electric powered models. I've never flown a plane like the P7 but I imagine that it's flown nearly full bore all the time. Am I right?

I think your major hurdle is going to be prop clearance, as with the stock nose gear retracting an inch and a half into the leading edge of the wing, there is not much extra clearance with an 11 inch prop. You might be able to squeak by with a 12 inch prop, but I suspect you will clip the ends on more than your fair share of props. I think going any further into the meat of the wing would compromise the structural integrity of the wing, and then there is also the issue of making the wheel wells in the wing larger to accommodate additional length on the mains. Given that the arf is so well made, I would be reluctant to start hacking into it. I would think it would be much easier to scratch build any number of classic airframes to the specifications you require for the chosen power plant, with the additional benefit of selecting light construction material to help with overall performance of the end product. In my mind you may spend almost as much time figuring out and executing the mods to a P7 airframe as it would take to construct a new airframe from scratch. The other option may be to use a CAD program and have your parts laser cut to your specs, for example lots of lightening holes every where you can squeeze them.

I find the electrics very interesting, not sure if it will ever be my cup of tea, but I still think they are cool. It would also be great for those people that may live in areas where noise may be a major concern.

Can you generate the required thrust on an 11 inch prop with a large pitch? If so I think you could have a real rocket on your hands. Please let us all know what you figure out, I for one am very interested in whether or not it’s a feasible option.

The other option might be to do the electric setup with longer than stock fixed gear.

One other thought. Is a three or four blade prop an option ?

Mike,

Do you know what is classic pattern flying?
I ask this because I read : I've never flown a plane like the P7 but I imagine that it's flown nearly full bore all the time. Am I right?

Give me your answer.

Cees

I fly mine almost exclusively at full throttle, with down lines being the exception. I just love how fast and smooth it is, I’m addicted.