New Power Pod: lite-ply, top hatch battery access, better cooling, more space

[ProfessorFate]

Have you seen End of the Road RCs FT Mustang with top hatch access?
What about Nerdnics nn P-39 design, tough, huh? good construction ideas there.





Before I even built my 1st power pod for anything I already had a list of special features it just had to have.

This power pod is somewhat specialized in that it is tuned for the FT Mustang and anything else you can make it fit.

A developmental process made this come about.

I started building the standard FT Power Pod but with my choice of materials
There is a 1st pod that's almost finished with built in thrust angles of 4 degrees Right and 4 degrees Down made to fit the Beef Suppo 2217 using a gws 9x5 ep, it uses blind nuts and allen hex head machine screws, because I like to be able to easily remove or switch out motors.

Features:
1: Durable lite-ply 1g/inch, won't get crunched on hard nose-ins, cut big holes in face for cooling
2: Built-in thrust correction 4deg Right & 4deg Down
3: Top hatch batt access, just set it in there, plug in and close hatch, hatch will hold batt with a pin n spring
4: Space problem for ESC solved, 3/4" rails will go on bottom as spacers, ESC goes here and will get plenty of cooling from the front
5: 6-32 firewall blind nuts ( for blind squirrels ), use w/ hex head screws, easy to swap different motors

Add: make a bottom shelf in the fuse that the pod will be supported by, you might even leave out side pinning the fuse then, with it also taped at the top of fuse/pod.
You decide where you want to put internal cross braces to hold the top and sides against any side pulling forces or just to hold it together good, maybe front, back and middle?

Just set it in your FT warbird, tape the top pod sides to the top edge sides of fuse lengthwise

That fiberglass sheeting you see is behind the clear canopy and is a very hard hand grip to handle/remove canopy by.

*** I did start out building a stock FT power pod out of lite ply, but wanting the top access hatch to put bat in pod, like if you have seen End Of The RoadRCs FT Mustang? It just ended up this way, all of these I believe are good ideas, but, this could have been planned better, like one whole panel for the sides extending that extra 3/4" where the spacer will go

Another one with all these ideas, but, just a better layout, would really be the thing to do, and not just stumble on this, this way, but it's discovery as you build, I guess. I'll know better what to build and plan for the next one.




Actual Size here too, I used the WRX formula I made up, I wanted 11"=W, image =32.5"=X, rate "r" to decrease=.3385 so 34% worked just fine

This image was taken close up so you get dimension errors on a side view, that would be reduced on a more distant picture, in natural light 10 feet away

Here's the full size plan of the 40 inch FT Mustang made disguised as a Hawker Hurricane with the new power pod design:




This eliminates a little of the top and nose construction, provided, you build a Hurricane or a different canopy cover.




After you watch The Battle of Britain ( 1969 ) with Michael Caine, Robert Shaw, Kenneth More, Edward Fox (Day of the Jackal) and Laurence Olivier, you may want to build a Hawker Hurricane.


"We have before us an ordeal of the most grievous kind. We have before us many, many long months of struggle and of suffering. You ask, what is our policy? I will say: It is to wage war, by sea, land, and air, with all our might and with all the strength that God can give us; to wage war against a monstrous tyranny never surpassed in the dark, lamentable catalogue of human crime. That is our policy. You ask, what is our aim? I can answer in one word: It is victory, victory at all costs, victory in spite of all terror, victory, however long and hard the road may be." Winston Churchill


Well, then, go see Reach for the Sky, The Story of Douglas Bader ( 1956 ) Kenneth More, another great movie with Hurricanes.

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Now the New FT Power Pod IS Planned Better Right Here:

OK so here's an update, I was obsessed with this idea of making a near perfect power pod, and noticed that I was really spending too much time on the hatch cover, so I decided to simplify it (make a flat wood cover and add canopy detail later, make a functional pod 1st) and see where I could also expand the dimensions and design this pod for 2 whole piece side panels, and also for use with canopy making, HEB now has this real tough poster paper ( $0.57 ea ) that would be good for those soft spots on top.

Have no fear about weight, there is so much benefit to this construction that it's worth it, and this lite-ply $10 for one 1/8x12x48" sheet (sold in a 6pack tho) is only 1 gram per square inch, the 1st one above mentioned is about 4oz right now.

I used real strong 1/4" hobby ply for the firewall, this is what makes this work so good, you can drill lots of holes for cooling and even a little bit remaining is strong, I drilled and cut away about half of the 1.75x2x.25" firewall and installed 6-32 Great Planes blind nuts for the motor, these are the ones with the large disc feet, get them at Amazon, 24 pack for $5


The picture with the dimensions pretty much tells you most of the story
Put the battery behind the motor, velcro it down and maybe put a spacer over the battery, tape to the bottom of the hatch
The ESC, glue or secure with zip ties under the battery in the lower compartment
make a hole for the ESC conn and radio pwr feed
make another hole to feed the motor wires to the bottom 3/4" space used for the ESC, the Suppo Beef 1340kv motor has stiff wires so I made a hole in the firewall then straight in-line thru the deck to the ESC
Glue some triangle stock on bottom of the deck where the ESC is, leaving max flat, clear space for the battery above
Some half dividers may be needed to strengthen and hold the pod sides, the outside dimension of the pod remains 2 inches so it should fit a lot of swapables, the Length was increased to help make most canopy schemes work, the Hurricanes and BF 109s all fit forward of the wing trailing edge, Old Crow NA P51 "B" back is even with the TE, Glam Gal NA P51 "D" is long hanging past the TE, FW190 is long past TE just like the Glam Gal Mustang.
By the FT Mustang Plans, this pod will sit right over the top of the wing, that nice straight bottom edge of the pod is supposed to rest on a shelf you build into your plane, easy enough, just 2" by 16" glue bottom or both good

The only thing needed to hold this pod in your FT DTFB low wing warbird is just taping the top edges of the pod to the even top edges of the airplane and it's done, in your construction, try to leave nice long clear areas to tape on both sides of pod for this purpose

I hope I did not leave anything out, I went over and over these numbers checking the fit and to see if it all added up right.
If you think it's too long, after you build it, it's easy enough to trim if you think 16" is too long, I know I put it a little past the bend in the fuse tail, won't matter much tho

There are supposed to be 1/4" dowels used both as stiffeners glued to the bottom of the hatch which is also supposed to have either 3/16" or .25" overhang both sides to match the foam board

You taper the front of these dowels and the insert into tubes made with epoxy and fiberglass, you just bunch it around wax and tape covered dowels, tamp it down nice n smooth, let it cure hard, pull off tape n wax paper and you have things that hold the front of your hatch, also you can just glue a piece of wood under the front of the hatch, you will still want a stiffener for the hatch tho and some kind of spring loaded pin closure at the rear, I am still working on this part
Some kind of small scraps should be glued under the hatch to make it fall centered over the pod, so that secures the hatch 3 ways, front, sideways and sides resting on pod, and pin the back closed against a stationary vertical bulkhead and remember not to close up the pod, you want air to flow thru it,
air should flow clear thru the bottom opening where the ESC is and out the tail
air should flow easily thru the firewall you can make big holes in this stuff but it takes good sharp drill bits



*****************************************************
**** Hey!, I made just one minor mistake and found it while cutting out the panels.
No big deal, and if you make one like this, cut out 2 panels 2 7/16" by 16" that's it!
Make a hood 2" long by 2 3/8" and the hatch 16" long by 2 3/8" to overhang the sides at the same height as the foam board, it's 3/16" each side.
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View attachment 56127

Now this is it, the New Lite-Ply power pod actual size, and dimensions checked against the FT Mustang for fit.

View attachment 56134

This drawing of the FT Mustang is super because it does not have all those @#$@#Q$%!! grid marks on it!



Now I really tried to make use of all available space, so if you find the wing too tight against the pod, just cut out a little bit of the bottom of the pod only where it touches the wing, might only be one or two 16ths.



You should build this, post and let us know how you like it.

Imagine the work this will reduce by already having the top front quarter of an FT Spit/Mustang/Hurricane/Racer/BF 109 already done when you start to build.

Don't mistake it, on the drawing, the side panel is 16" long by 2 9/16" at nose and 2 7/16" aft.

On this one, I don't know if I will put thrust correction, I'll know after I finish the 1st prototype and install in an FT Mustang dressed up as a Hawker Hurricane.

 

[ProfessorFate]

Canopy aft piece pattern

Here is the pattern for the piece aft of the glass canopy for the 1st pod design, might also stick one of these on the better 2nd pod design, it provides a very regular curved shape and a tough place to grip the hatch by to remove the cover

When I scored lite ply to bend around the curve, it just broke too easily, so, I just cut out 2 stiff cardboard pieces from that tough poster board HEB has for 57cents, cut 2 wax paper slips and 2 layers of fiberglass cloth, mixed up some epoxy and put the wet double glass layer between the wax paper and that between the 2 hard cards and held this around the curve till it hardened, worked great and smooth.


The way this piece works good is if you attach the trailing edge of the clear canopy over the LE of this piece, then build the aft part that goes to tail behind and lower than this glass piece so there aren't any fwd edges to catch the wind, might make the aft part longer so it would overlap aft better because it will be the removable hatch/canopy.


I may want to just go ahead and make a nice permanent canopy for the new design out of this stuff too


The 2nd design has more space, much better thought out

for the hatch you could leave out the stuff about the glass epoxy pin sockets at the forward end and just glue a piece of wood under the hatch that would both hold the hatch centered and keep it on the pod, the hatch would still need something to stiffen it tho

this pattern is something that nice that might be carried over and applied to the 2nd improved pod

View attachment 56212 View attachment 56213

Here you can see that there would be less airplane to build around the nose area, and the new pod drawing is 16" or 1.5" longer, the rudder and elevator servos could be mounted in the back of the pod.


With more room, there are more options.

 

[ProfessorFate]

Found a minor mistake while cutting wood to make the new one!

*****************************************************
**** Hey!, I made just one minor mistake and found it while cutting out the panels.
No big deal, and if you make one like this, cut out 2 panels 2 7/16" by 16" that's it!
Make a hood 2" long by 2 3/8" and the hatch 16" long by 2 3/8" to overhang the sides at the same height as the foam board, it's 3/16" each side.
******************************************************
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[ProfessorFate]

Picture to clarify before assembly

A slight typo in the pic with the dimensions, that space for the ESC has 5/8 (not 1 5/8") and the top of the deck is placed 3/4" from the bottom edges, see in the picture on the wood.

So if you might consider building this, hope I hear from you

I considered the firewall a floater, depending on what size motor and space needed, the length of the pod floor is 13 7/8" and some triangle should be put on the bottom of the pod floor to help bond and hold it in place and square

This does leave, as planned, 1 11/16" vertical space in top of the pod floor clear space for battery and radio gear etc

those angular guide marks are for the fwd side of the firewall





At the top edge the middle mark the angular line starts at is the top Right side of the firewall that will be set back at that point at 3 degrees

The bottom mark of the line is 3R + 3D = 6 degrees or 4.6mm setback on lower Right corner

 

[ProfessorFate]

Motor offset is tight between the 1 3/4" limit, but it will work



Just as it will sit in the pod

 

[ProfessorFate]

 

[ProfessorFate]

Mostly assembled now, lacks hatch, hood and closure mechanism



See how under the pod the ESC will get good cooling, big hole for the motor cooling, those screws need to be trimmed and all 4 fit just perfect

The only awkward thing is the length of the wires puts the ESC too far back

The optics in the pics don't honestly show it, but it was very carefully measured 3R and 3D and I shifted the motor left as much as possible, needed to go 2 more mm to center the prop but it's OK, close enough

 

[ProfessorFate]

Cobra 2820 motor for this pod



apc 10x6e 57 + oz thrust

apc 11x5.5e 70 oz thrust

 

[ProfessorFate]

Just about finished, 19.27oz Motor,prop,batt,esc

Last is to see what size Hurricane, thinking of scaling up to either 45 or 48" WS and using some of that better Ross foam board from Walmart, reported to be 5mm thick over the DTFB (Adams?) 4mm thick.

With an apc 10x6e this system easily gives 57oz thrust and if needed, apc 11x5.5e makes 70oz at the motors limit tho



This is the pod made for easier canopy construction using foam, it will just have a flat top cover with a locking pin on the hatch to hold the battery and the hatch


I often think in terms of relating things and using other patterns or techniques, so I am looking at Nerdnics constr methods in his Mustang and nn P-39 articles, using the best of those ideas and building a 45 to 48" Hawker Hurricane.

When I fig the size and see where the back of the canopy falls I'll make the flat hatch for the pod and it's done

 

[ProfessorFate]

New more specific wood pod for Mustangs and similiar warbirds

I kept on thinking about how I would like a hard nose and something other than rubber bands and dowels to hold the wings down and still like the top hatch

So here's a new plan, I missed one thing on my firewall, it's too far fwd by 1/4" you can see, I corrected that on the new drawing, this is almost finished

Where's the "BEEF", well I wanted a good pod to use with the altitude hobbies 1350kv "Beef" motor that I have heard Josh mention, and it seems just right for models up to 40oz depending on what the plane your flying is, so here's a pod for the "Beef" motor and FT Mustang or Low Wing Warbirds

The wing saddle is shaped for a 10" S5020 airfoil, in case I want to try hard to pattern my wings like that, it's close to the FT Mustang wing, and I listened again and again and looked at FT Spit, Mustang and other warbirds, Mustang favors a long nose, but, that makes things easy on us, you never have to add weight with a long nose, only with a short nose.

At the bottom fwd I will use heavy const paper attaching the left to the right bottom and making a kind of saddle or cradle to hold the bottom fwd side of the pwr pod, holes in the pod will be needed to access the ESC and a hole at the back to allow cooling air flow, this is going to work real good, tape the top edges and nose to the painted plane,bolt on the wing, hook up the servo linkage and fly

The bottom of the tail is left open and vague, basically take off from the bottom back corner and connect to the pod, it goes slightly deeper and I left off the Mustang cooling scoop in case I wanted to belly land in grass

That blue mustang side view someone posted has been very useful and I think I will repost it here too.

View attachment Mustang Fuse wing saddle 5 for 8th skin under wing pr 3.jpg





See the other plane, My wood version of the FT Bushwacker, modeled after the Savage Bobber with a 45" wing span

Leonard

 

[ProfessorFate]

Warbird "BEEF" motor power pod for 9.25 inch wing chord is done 20.3 oz

I finally finished something, went kind of slow but this is all done except the pin or magnet hatch mech then to make a plastic canopy cover in front of the f-glass hardpoint/grip.

The 1st plane this will go in is not an FT Mustang but a Hawker Hurricane using close dimensions of the Mustang in terms of stabs size and wing size, fuse size and the 3 section Hurricane wing

I'm gonna try to put a tail wheel in the fuse just like the blue Mustang picture, it looks pretty easy, a good idea that would not wear out the rudder.

This should go faster and easier since most of the plane is done and it won't fatigue due to rubber bands and dowels ... with bolt-on wings

Tell me what you think, if you like the idea and think you might build one too.

Those machine screws and 6-32 blind nuts make it easy to trade out motors if you want to try a different 22mm motor and with the big holes they stay cool and it's easy to oil the bearings front and back.

What's in there now is the 1350kv Suppo ( Dr Kiwi of RCGroups tests it at 1350kv, see flybrushless.com ), starting with gws 9x5 props, but later maybe wanting to see different performance, or longer run times, might try the Suppo 950kv motor.


You may not see it in there but I helped the epoxy bond with some fiberglass and then put wax paper over the outside to press in and make joints smooth.




Oh, I also built in thrust correction, 3deg R, 3deg Down calculated on a 44mm square, the bottom left corner, looking at the nose, is 4.6mm deeper than the opposite corner, and the adjacent corners are 2.3mm deeper than the 2 O'clock zero point reference, where I call the origin



Does anyone else refer to pod tabs as 4 and 5 and 11 and 12 referring to the origin as the top corner behind the firewall?

This is what I look for on all FT plans, the tabs, even tho I don't use them on my pod.





See the big holes for cooling the motor and battery top level and the big hole bottom side for cooling the ESC?
I finally found my wood carving bits and my dremil tool, and with this 1/4" thick hard plywood, you can sure carve out big cooling holes neatly, all around the pod and motor.

After finishing this and looking at it, I think it might even run cool with a spinner too, because the only thing on top is the battery, and it can still get cool air around the spinner.


Now to finish the last details, build and install in an FT-ish 40 inch ws Hawker Hurricane.

Leonard

 

[abieex]

Amazing effort. Great job!

 

[ProfessorFate]

Thank you, here's some graph fun for the "Beef" motor

I don't remember where I last posted this here or RCGroups, I really got into graphing because sometimes you don't get enough from a test but if you have a few points, a good graph can fill in the blanks at the top or bottom or middle.

Dr Kiwi gave test results with thrust that stopped at 9.7v and 36.4 oz thrust, well what thrust can we get at the nominal or average 11.1v with the Beef motor and gws 9x5 ep prop?????


"Survey said....." 46 oz!

Now of course we still have to use this with the caution that we know the current/power limits of the motor in question, 20A for this motor and at 9.7v it was 19.6A on this test point


####******* Well the funny thing is I was thinking I remembered a different current limit listed and just found it's on the test page at flybrushless.com where Dr Kiwi listed the "Beef" motor as having a limit of 22 Amps, not Altitude Hobbies current listing of 20 Amps???????

Well I don't know, I have an Eagle Tree testor and a temp sensor to put together with a testing rig, I'll eventually figure out what's true. 20, 22, or even 25 amps and later I'll build a thrust test stand too.

I still enjoyed getting the graph thing going and I use it for other motor tests, sometimes to see what falls in between on a thrust test like on the innov8tive site about the Cobra motors


You may find this particular graph paper very useful, as I did, I made it line by line in paint shop, it's the number multiples and the resolution and range of display that I really like.


You will find it is very accurate, as good as your points and curve matching.

Try it, I'll post up the blank graph I made.





There's this chart I found after putting together this post



I know you may wonder, what's all that extra space for....right?

Well when your playing with a graph, after you put in some good data points, the best easiest way to fit a curve here, is to just play with the circle function, elongate it, rotate it, till one side of your circle, the curve, fits the points best, then treating that circle as a layer, erase away the part of the circle that is not the curve on the graph, then merge it with the background image of the graph.

You need the extra space to play with the curve of the circle.


Try it out, I put a lot of thought into this blank graph for the purpose of those unfinished motor/prop/thrust tests where we might want to know how things will work at some point other than just the extremes, like all the charts show!





Leonard

"Push the button max!"




Here's some more graphing info: thrust in ounces from the APC 9x6 at any rpm based on some test points from Cobra motors at innov8tive.com



How many rpms is this prop good for? 145000/9 = 16,111 rpm so like 90oz of thrust 5.625lbs.

 

[ProfessorFate]

Don't use BBQ skewars till you try these magnets at Home Depot

I doubted these at first and thought some kind of fastener was the only way, but these are very strong, and they are at the back of the hatch, giving them leverage over the load of the battery in the pod



They say don't cut into these magnets because they contain poisonous materials, but I scored the sides and bottom deeply, epoxied them with z-poxy and added loose fiberglass and it's holding really good

I'm going to use these more often

Leonard

 

[ProfessorFate]

This power pod is about finished.

Tonight I started looking at making a wing with 12 inch root chord extended into 3rds (60 inches) so the panels wouldn't have to support so much weight. The extended view is here.

These hpdlrk wye motors use 25% less power on 3s 30 amps for 4# thrust with an apc 12x8.

Manufacturers delta motors take 40 amps to deliver 4# thrust with either an apc 12 or 13" prop.

If that sounds good, consider getting a 4008 multirotor motor. Keep the base on it, wind it with 19ga for 850kv. Best with apc 13 x 8 for 2.5 to 4# airplanes wings 48 to 60 inches

Just tested a new motor 1005 kv wound with 18ga using an apc 13 x 8 got 6930 rpm got 69.63 oz thrust 9.8v 32a 313.6 watts.

I think the 13 x 8 works better by reducing rpms

The motors in pod, storch, and Savage Bobber are same but wound 850kv 19ga 28 amps but great, they'll use 12 to 14 inch props easy on 3s