Numbers needed - P-Force

[Paul Taylor]

Can someone put a ruler in a PForce and post up the numbers please?

Thanks in advance


Sent from my iPhone using Tapatalk

[RC Storick]

Three sixty one

[Mike Griffin]

Hi Paul

I took these numbers off of my plan .... if this is what you are looking for

Wingspan - 51 1/4"

Area - 502 Sq In

It says the length is 40"

Hope this helps Paul.

Mike

[Serge_Krauss]

I just re-measured my plans. I too had been using some advertised figures, but unless I've made a mistake (ever more possible! Edit: I did!), the wing area is only 483 (mistake - its close to 497) +/- a couple square inches. These are my own plan measurements (taking ino account that no two will be exactly the same , and the plane will come out differently anyway)"

Fuselage, measuered from spinner backplate to...

1) Wing l.e.: 7 1/2"
2) Wing t.e.: 18 9/16"
3) Stab l.e.: 28 7/16"
4) Stab elevator/hinge line: 32 3/16"
5) tip of tail: 37 1/4"

Landing gear (axles):

1) Behind Spinner  Backplate: 7"
2) Below Fuselage C/L (thrust line and two chords): 4 11/16"

Wing:

1) Inner Panel Span: 25 7/8"
2) Outer Panel Span: 24 15/16"
3) Full Span (to widest points: 50 13/16"
4) Span between outer edges of tip ribs: 46 1/2"
5) Tip spans: 2 3/16"
6) Root Chord: 11 1/16"
7) Tip Chord (at last rib): 9 1/8"
8 ) Area: 483 in²   497 in²

Horiz. Tail:

1) Widest Span (at tips of elevator): 17 7/8"
2) Hinge-line Span: 17 5/16"
3) Stab Root Chord: 3 3/4"
4) Full Root Chord (from extending elevator trailing edge lines inward to C/L: 6 3/4"
5) Elevator root Chord (from extending t.e. lines to C/L): 3"
6) Tip Chord: (average at/across hinge ends): 4 5/8"
7) Area: 98.5 +/- 3 in² (19.8 +/- ?% of wing)^*8
    * Another Edit: inner elevator halves do not extend to the fuselage at their t.e. That makes the horiz. tail area less than stated.
Wing Sections: Mike told me they were NACA 0018's, but after the laser cutting and rib stripping, they measured out at around 17% (a bit less) at my root. The number I recorded for max wing thicknesses:

1) Root: 1.84"
2) Tip Rib: N/A

Tail Moment Arm Length - old figures:

1) between aero centers of wing and tail: 19.5"
2) From C.G. to a.c. of tail: 20.25"

I had calculated the TVC and like things, but those depended partly on the advertised areas. So I'd have to redo that stuff - and check my computations. This means that I may have designed my present project slightly off too. If you know the P-Force's shapes, you could come close to duplicating it, if that's what you have in mind. You'd need the spar information too. Getting plans from Mike Pratt would be better. Anyway, since I didn't really know what you wanted, this is a big FWIW. Time to blow some snow!

SK

Edited to fix typos andchange wing area to about 497 in² (I had only added one tip area).

[Mike Griffin]

I have had several of these planes and they fly great.  Thanks Serge for the thorough numbers.  I did not know how detailed Paul wanted to go.

Mike

[Paul Taylor]

Wow that should cover it!

[Dan McEntee]

  This might be the perfect time to compare the ARF kit to the original design and Mikey Pratt's plans. I have been wanting to do that but haven't got around to it. The ARF has leading edge sheeting and the short kit doesn't, so there may be other differences made to facilitate ARF construction.
   Maybe Mike will see this and fill in some blanks? I sure do like my ARF version and plan a kit built edition.
   Type at you later,
    Dan McEntee

[Serge_Krauss]

Just as I was turning in (early) tonight, I had that nagging feeling that often comes long after a mistake has been made. I realized that my wing area above was short one wing tip. So my revised area is 497 in², which is a lot closer to what we have been using. I made the correction in the original post above. This is +/- a couple square inches. 'sorry for the error.

I had buil my P-Force a bit heavy, and I'm trying to rectify that, despite having a heavy wing structure. One thing I did after stripping off the old silkspan was to insert stub ribs between the original ribs to help keep the leading edge closer to the rib design by reducing sag, something the ARF's sheeting may accomplish (I hadn't noticed that). Now all I have to do is get the silkspan to stick with this butyrate dope that seems to have lost its adhesive qualities. I'm mystified, but intent on flying this gadget.

SK

[Geoff Goodworth]

Don't want to seem picky Serge, but Mike's plan says wing area 502 sq in. The plan also says 51 1/4" span and 40" long. I haven't measured the plan or an aeroplane, just read the numbers from the plan.

[Serge_Krauss]

I mentioned the discrepency in my post. I measured my plans carefully and got the figures listed. It's quite possible with just 1.0% copier error to get half an inch error on copied plans for a 50" span. You can, however, get all measurements keyed to any preferred measurement by simply taking the ratio of preferred measurement to the associated measurement from plans and multiply that ratio by all the other measurements given. That will give you all dimensions proportional to your one chosen dimension.

For instance, if you prefer a 51 1/4" span. multiply all measurements I gave you by 51.25/50.8125 = 1.0086. Notice that this is less than 1% larger, well within the errors perpetrated by most people who have tried to copy my own plans accurately.

If you multiply my estimated area by 1.0086² (=1.0173), you get a wing area of 505.6 in², which is pretty close to the margin of error I estimated for my figure. That all comes from estimating what percent of a triangle ot rectangle the tips take up. Other than having CAD give the area of plans in CAD, counting tiny squares and parts of squares on graph paper,  or knowing all radii and lengths used in drafting the plans, there just isn't a better way to to do it.

I just re-measured the fuselage length, and it is indeed 37 1/4" from the spinner backplate to the tip of the tail, nowhere near 40", which is over 7% too long. The length from the tip of the spinner to the tip of the tail is slightly more than 39 1/2". This would only be about a 1% error. However that particular measurement is useless. FWIW, if your copier cannot be adjusted by .001  (1/10 %) increments, then you can still get closer to what you want by taking whichever percent (e.g. 1.01, 1.00, or .99 magnification) comes closest. If the copier is good for 0.1% increments, then you can come within 1/16" on this span. So the figures given will allow you to size the plane proportionally as you please. I wouldn't steer you wrong.

So,... you have my plan sizes, which was what was requested, and a way to build to the advertised size by using the figures I gave. That's the best I can do.

SK

[MikeyPratt]

Hi Paul

I took these numbers off of my plan .... if this is what you are looking for

Wingspan - 51 1/4"

Area - 502 Sq In

It says the length is 40"

Hope this helps Paul.

Mike

Mike,
Yes these are the correct numbers.  The plans were drawn in CAD and are very accurate along with laser cut drawing files.  I still have all the files and drawings.  Copies of the plans can be off slightly because of moisture/humidity in the area you are from.  However, I think any deviations from original drawing would not make much of a difference except for parts fit.

I'm working on other new Force designs that should be "KILLER" and almost ready to fly as soon as the snow goes away.  I was trying to finish one of them before the snow hit but just didn't get it done.

Later,
Mikey




 

[Paul Taylor]

Mike,
Yes these are the correct numbers.  The plans were drawn in CAD and are very accurate along with laser cut drawing files.  I still have all the files and drawings.  Copies of the plans can be off slightly because of moisture/humidity in the area you are from.  However, I think any deviations from original drawing would not make much of a difference except for parts fit.

I'm working on other new Force designs that should be "KILLER" and almost ready to fly as soon as the snow goes away.  I was trying to finish one of them before the snow hit but just didn't get it done.

Later,
Mikey




 

Sure would like to see a picture Mike. 

[Mike Griffin]

Hi Mike

Looking forward to seeing it.  The Primary Force is an excellent flying plane and I know the new one will too.

Mike

[Crist Rigotti]

Hi Mikey!

[MikeyPratt]

Hi Mikey!

Hi Back Christ,
Whazz up!!!

[MikeyPratt]

  This might be the perfect time to compare the ARF kit to the original design and Mikey Pratt's plans. I have been wanting to do that but haven't got around to it. The ARF has leading edge sheeting and the short kit doesn't, so there may be other differences made to facilitate ARF construction.
   Maybe Mike will see this and fill in some blanks? I sure do like my ARF version and plan a kit built edition.
   Type at you later,
    Dan McEntee

Hi Old Buddy,
As far as the comparison between the P Force and the ARF version, they are very close from all outside dimensions.  They did modify the construction so it could be produced on an assembly line (so to speak).  You have to remember that they are assembled by people that don't fly models, just work at the plant and do what they are told to assemble the model.  Structures were changed to save wood and maximize the profits of the finished product.
For the most part, they do a great job.
The leading edge sheeting was added to speed up assembly.  The addition of the leading edge sheeting may have helpfully (slightly) from a performance viewpoint, but I couldn't tell any difference between the two.  Having said that, mine was 4 to 8 ounces lighter than the ARF versions.

I've done so many experiments to the P-Force trying to improve it, i.e. Adding weight, trim tabs on wings and elevators, thrust lines, down thrust, positive incidence to the stab, and many more.  In the end, it created more problems than fixes.  But that is why we trim models looking for the awesome trim setting that greatly improves performance. 

Later,
Mikey