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Author Topic: Capacitor Sport  (Read 8072 times)
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frash
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« on: July 26, 2011, 11:30:25 PM »

Recently I built and flew capacitor-powered indoor planes per the proposed Science Olympiad trial event rules at http://www.soinc.org/sites/default/files/uploaded_files/Wright%20Stuff-Capacitor.pdf.

These indoor duration planes used a single capacitor with rated voltage of 2.3-3.0 volts and maximum rated capacitance of 10 farads. Charger is limited to two AA alkaline cells. Required minimum all up weight must be 12g.

I decided to see what sport models would work outside using similar equipment. The Air Hogs Aero Aces Jet was the foam left after all the electronics had been used for another project. I added a Illinois Capacitor Model 106DCNR7Q 10-Farad, 2.7-Volt Super Capacitor purchased from NooElec.com or from Allied Electronics. The 7-mm diameter, 2.3-ohm brushed motor was obtained from BSD Micro RC. The prop was a 65-mm diameter TriTurbo prop by Plantraco that was also obtained from BSD Micro RC.

All up weight as flown was 16.7g and flights were 20-51 sec. If this will fly okay, surely you or I can build and fly lots of better craft.

The second test used a leftover Skinny Pussycat with only a 5-Farad capacitor with the same type of motor and prop as the jet. The heavy motor stick was cut down. The wing was lowered, and the stab covering (on bottom per plan) was cut out and recovered on top to reduce stalling. All up weight was 9.7g. There were a least 20 flights today usually 30-40 sec duration. Some flights were in the 20s. Three were in the 50s with the best 56 seconds. Several times the plane seemed to turn right and exit from a thermal.

These capacitor sport planes are simple, inexpensive, good for small fields, and maybe suitable for my grandchildren before too long.

Fred Rash
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PeeTee
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« Reply #1 on: July 27, 2011, 02:03:47 AM »

Fred

Thanks for the information. The Skinny Pussycat looks good for both indoors and out, and while capacitors are probably not as good an energy source as lipos you do get a very quick recharge.

Oh dear, another thing on the to build list

Peter
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Zeiss Ikon
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« Reply #2 on: July 27, 2011, 07:15:13 AM »

while capacitors are probably not as good an energy source as lipos you do get a very quick recharge.

The other thing you get with capacitor power is simplicity -- no need to worry about damaging lithium cells by excessive discharge, and no need to cut off motor run to avoid OOS flights; the capacitor handles both of those issues.  You do get power decay as the capacitor voltage drops, but that just means you trim much like a rubber power model -- for burst, cruise, and glide.  I see the Olympiad doesn't allow folding propellers, but they'd improve the glide in a sport model...
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Wout Moerman
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« Reply #3 on: August 04, 2011, 07:49:24 AM »

I have two Revell Crazy Wings capacitor powered models. They do fly but they both suffer from broken popellers and flight times were only around 10 seconds. I did modify one to save some weight but the broken prop stopped further development. I am still thinking of making new props, but they are rather tiny.
Nice to read about your developments, much more succesfull than mine.
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frash
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« Reply #4 on: August 08, 2011, 11:31:15 PM »

The Skinny Pussycat is probably actually a Starved Pussycat. Friday old flying buddy Hank the Timerguy and I went to a local park. The capacitor Pussycat made consecutive flights of 1:18 and 1:15 and lots of shorter flights. This was about midday at 90-95 deg F. Since it did not fly away in these thermals, maybe it is hard to lose. I added 1/64" more wing incidence and launched hard and steep to take advantage of the power burst from the capacitor. It still came down from the thermals.

Hank flew two Harbor Freight RTF Twin Tailed FFs Item 43678. I think that these have been discontinued but have been cheap, fun, and expendable for us and two other guys. Hank lost none on 8/5, but on the previous Friday (7/29) he lost two of these OOS with times of 5:03+ and 12:15+.

Fred Rash
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frash
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« Reply #5 on: August 24, 2012, 05:08:57 PM »

Yvette Tandem Capacitor powered OOS flight

I built a scaled up and stretched version of Bill Brown's Yvette tandem indoor rubber design but flew it away outdoors (6:17+) OOS on Wednesday as described in the indoor section at

http://www.hippocketaeronautics.com/hpa_forum/index.php?topic=12079.0

Fred Rash
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frash
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« Reply #6 on: July 01, 2014, 11:20:11 PM »

Capacitor Powered Foam Flying Wing

This is a FF capacitor-powered  "Dizzy Chick" built from 3 mm Depron and modified slightly from the plan at http://www.modellbauvideos.de/index.php?id=4
Original design was by Torsten Hill and posted by StephanB on RCGroups several years ago. I built two for Air Hogs Aero Ace differential thrust RC. One thermaled away and the other was discarded when the electronics wore out.

This one uses 2.7-volt, 10-farad Cooper Bussmann supercapacitor ordered from Mouser Electronics, a 7-mm SS “orange”( ~3.5-ohm) brushed motor from BSD Micro RC, a Plantraco Triturbo 65-mm diameter prop, and is charged with 2 AA alkaline cells. Weight was 12.93g as flown today.

This simple sport craft has been flown both outdoors and indoors. Original motor was the hotter 2-ohm one and gave too much right bank. A 10-ohm prop was too weak for flight.
Both 7-mm motor and 10-F capacitor are mounted in small paper tubes. Launch is by holding the center wing TE. A rear ventral subfin might be convenient for launching. Sticking your finger in the prop gives no injury. There are only 12 foam parts, so this is really high tech (Grin).

Yesterday indoor flights with 15-30 sec charging times were 52-57 sec. When I realized that the charger only read 2.94V, I used new AA alkaline cells and 30 sec charges gave times of  1:08-1:14. Height was 30-50 feet.

Outdoors today charge   Flight      Comments
15            0:48       One swallow joined in formation
15            1:42      ~12 swallows joined in
15            1:20      
15                ~0:45      Very turbulent air but craft recovered
                  Landed in tree but recovered

Fred Rash
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frash
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« Reply #7 on: July 01, 2014, 11:30:41 PM »

Capacitor Dizzy Wing photos.

Fred Rash
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frash
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« Reply #8 on: July 01, 2014, 11:32:15 PM »

Last
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« Reply #9 on: July 02, 2014, 02:43:22 AM »

Thanks Fred

Something else on the never ending list of things to try Roll Eyes
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frash
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« Reply #10 on: July 14, 2014, 10:49:52 PM »

The most recent Economist for July 12 2014 describes the use of ultracapacitors for bursts of power for electric cars, buses, and trains so maybe these simple to use systems will continue to improve a lot.

http://www.economist.com/news/science-and-technology/21606715-new-sort-storage-device-gives-lithium-ion-batteries-run-their

Fred Rash


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frash
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« Reply #11 on: November 09, 2014, 09:58:53 PM »

Update:
This capacitor powered Depron foam Dizzy Chick flying wing made at least 8 more one minute or longer flights before being lost in woods and briar thicket at a local park in mid-July. My search was made without water on a hot day without a machete or pruning shears to penetrate the briars. Nevertheless I was only a few hundred feet from a fire station and had my cell phone. I never found the plane, but feasted on wild raspberries and blackberries. I even went back on a second day armed with pruning shears and the berries were even better.  Grin

This flying wing was replaced by another copy that made about 50 flights both indoors and outdoors before it flew away into trees with a flight time of about 2:30.

Therefore I have lost 4 cap planes to flyaways up OOS or into vegetation in the last year- an enlarged Yvette, a Prairie Bird No-Cal, and two Dizzy Chick flying wings. All designs were modified from existing rubber FF or micro RC designs.

Fred Rash
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scrubs
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« Reply #12 on: November 10, 2014, 09:25:49 AM »

Thanks for the update Fred. I've gotten away from electric lately and need to build something for it.

A couple of friends are flying models that I would have thought to big for the Parkzone P-51 motors they are using (but with lipos). One is a ON 28 which really surprised me.

bill
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« Reply #13 on: December 31, 2014, 03:49:34 AM »

Having been given a Hobby King Electric paper aeroplane kit with integrated pager motor, motor stick and Super Capacitor the obvious development was to modify a rubber plane to drop this complete power train onto. Hey presto, immediately successful outcome achieved flying both indoors and outside in calm conditions with an adapted iyi - R. Next step is to revise the design to align the motor thrust line correctly, remove a little weight where possible and upscale to notional 20” (E20 span limit).
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raggedflyer
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« Reply #14 on: December 31, 2014, 03:53:53 AM »

This is the iyi -SC version which was successfully flown indoors a couple of days ago but needs a little further trimming to slightly tighten the left turn….


iyi – SC (pronounced eyeye; SC = Super Capacitor)

Design: Super Capacitor powered polyhedral monoplane for indoor & calm weather outdoor flight with adjustable all flying V-Tail and sub Fin
Lineage: Variant of iyi – E (electric) and iyi – R (rubber) variants up-scaled to 20” projected span

Wingspan:  Flat 508mm (~20”), built 490mm
Wing area: 38395mm2   (59.5 in2)
Weight: 11.2g (0.39oz)
Wing loading: 2.92 g/dm2 (0.96 oz/ft2)
Power: Hobby King Product ID: 527000001-0

Construction: Flying surfaces, Laser cut 2mm depron, film covered
Fuselage, Laser cut 2mm depron and balsa with 1.5mm carbon fibre boom

Flight duration: ~1m (achieved with prototype)
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frash
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« Reply #15 on: December 31, 2014, 11:06:48 AM »

Looks great, raggedflyer. You have improved both design and craftsmanship on this thread.

Your craft should be good and may thermal outdoors.

Fred Rash
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raggedflyer
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« Reply #16 on: December 31, 2014, 11:55:17 AM »

Thanks for the comments.

No doubt about it thermaling. I lost one of the iyi - R rubber version last February (English winter) to a thermal fly away whilst trimming in calm conditions outdoors in preparation for indoor flying the next day. Consequently I'm wary about too good flying conditions! The prototype iyi - SC did 58, 68 and 57s outdoors over 3 consecutive flights in early December, the extra time being due to lift.
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julio
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« Reply #17 on: December 31, 2014, 06:00:59 PM »

Raggedflyer

I'm interested in your "alternative" building materials and your IYI designs.

Is it possible to share plans for the different IYI designs? Very nice "organic" and light subjects. I have no access to a laser cutting machine so I would see if I could manage to experiment.
What film did you use as covering and what kind of adhesive was used?

Frash

Is there any article or thread that you can point me with the very basics about the electronics  to conform an adecuate "power train" for this cathegory? I have no electronics knowledge and no electronic toys available to use as power.

Thanks!

Julio
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raggedflyer
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« Reply #18 on: January 01, 2015, 06:33:35 AM »

Design drawings

As I mentioned there are a series of iyi variants; Rubber (-R), Electric (-E), Super Capacitor (-SC) powered and a 3-channel RC version (-ERC). Each has been designed using laser cut depron flying surfaces and usually composite depron and balsa fuselages incorporating CF booms so in reality these models cannot be sensibly reproduced without a laser cutting capability. The ability to ‘add holes’ is essential to weight minimisation.

For that reason I’m not in a position to provide drawings yet but I’d consider expressions of interest in the longer term from anyone wanting cut kits.

Covering

This covering film has been used on all my indoor models because it is light, durable and presents well. It weighs about 4g/m2 and has a soft feel. It can be attached by adhesive and is heat shrinkable.

However, I have to confess to a mystery here as I was given a part used roll without any packing information so have not yet identified it.

What I can say is that it is sold by the UK company ‘Iceland’ as a sandwich bag wrap, in a double sided, sealed end, tear off bag format. My investigation so far suggests it is probably not High Density Polyethene (HDPE or PEHD). My guess is it could be BOPP (bi-oriented polypropylene) Film (because polypropylene is a very cheap commodity) but I don’t actually know. Do we have a chemist or someone with Food Packaging knowledge to help with film identification? It is not the stretch, self amalgamating film known in the UK as ‘Clingfilm’ which I think is called ‘Sarin’ in the US, nor does it have the feel of polythene.

I’ll included the Film Covering Process as a following post.


Power train

The power train has 2 key elements; the energy storage capacitor and motor. The user needs a means of charging the capacitor. It is helpful to have an indication of the state of charge and the ability to control the start of the motor run.

Some references are given to components in earlier replies to this thread but in my opinion the Hobby King Product ID 527000001-0 meets all these requirements in a very simple package at an amazing price. Remember this is essentially from a Kid’s toy paper aeroplane so definitely no electronic knowledge is required.

I don’t know what the value or source of the Super Capacitor is that’s used with the Hobby King item (anyone know?) but the motor is a 6mm brushed pager motor type.
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raggedflyer
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« Reply #19 on: January 01, 2015, 06:36:03 AM »


Film Covering Procedure


1.   Cut a bag off the roll – do not tear off to avoid stretching the film
2.   Trim off each end and both edges to create 2 superimposed sheets
3.   Separate the sheets (2 per bag)
4.   Lay flat onto a clean cutting mat
5.   Cut 16 pieces of masking tape about 10-15mm wide and 20mm long
6.   Tape the film down at 4 corners, then at each end of the horizontal and vertical centre lines, then finally in between each previous tape patch…

Each time a tape patch is added lightly stretch the film to remove as many wrinkles as possible
Work around the panel and lift the tape from the mat and reapply as necessary until most of the panel is wrinkle free. Don’t worry about the extreme edges.


7.   Apply decoration to the surface to be covered using a ‘Sharpie’ pen(s) whilst the item is retained in the laser cut panel
8.   Cut the surface to be covered from the laser cut depron panel and trim the tabs flush and/or smooth with clean 600 abrasive paper used dry


9.   Lay the surface flat, decorated side upward and dust over a coating of 3M Spray MountTM adhesive and allow to dry
(if you want to minimise weight consider masking the centre of the surface with a cut paper sheet)
10.   Place the adhesive side of the surface onto the film panel and firm down  (lightly roll over with a kitchen rolling pin is one method)
11.   With a brand new scalpel blade fitted trim closely around the outside of the surface, using the edge as a guide and remove the covered item
12.   The surface is now covered with film but the adhesive bond must be improved


13.   Set a film covering iron to a very low temperature (mine is setting 1.5 on a scale low/1/2/3/high) and allow to temperature stabilise

IMPORTANT – experiment here to find the coolest acceptable temperature

14.   Apply the covering iron briefly to the film ONLY around the outer surfaces of the panel to further activate the adhesive to secure the film at the leading and trailing edges, tip and root etc.

IMPORTANT – move around quickly and do not linger at any particular spot for too long

Pass the iron over and around the edges of the surface to seal the film edge

15.   At the same iron setting swiftly move the iron over the film to lightly shrink but avoid heating the surface edges



Notes:
When covering depron some curvature of the surface is inevitably introduce. Invariably this can be removed by heating the underside of the surface at the same setting, carefully manipulating as necessary. I also observe that the covering flatness may improve over time as relaxation may occur?

With the lightweight structures such as I have used it is very important not to over shrink the film and also with this particular film overheating can cause wrinkling that cannot be removed – in other words there is a low optimal temperature sweet spot to be used.

raggedflyer Iss1 01 Jan 15

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julio
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« Reply #20 on: January 01, 2015, 10:43:01 AM »

Raggedflyer

Well, this is a masterclass. Thank you so much for the time you spent to explain your work (impresive craftsmanship). Very kind from you!

About the film, you said a very important thing (to me); it is not an originally freeflight (or RC) destined film covering. This, again, means "alternative" wich mantains my curiosity and interest in your work. I have been collecting different kinds of very light covering materials (cutting bags in the way you described...). I can't find many of the materials frequently mentioned in the build threads, so "alternative materials" keep my imagination going.

A couple more questions.

In the pictures you posted I think I see a model with a flat profile wing and a model with a cambered profile wing. Is that correct or I'm wrong and both are cambered?

The dihedral or polyhedral is acomplished after or before covering? Could you describe your method?

The power train is a work in progress to me. I found a local source for pager motors and bought two initially, but still looking for a source of super capacitors here.

Again, thank you so much!

Julio
« Last Edit: January 01, 2015, 10:54:34 AM by julio » Logged

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« Reply #21 on: January 01, 2015, 12:31:42 PM »

To whom it may interest some infomation about Cap flying in Germany.

In the last Thermiksense 4/2014 (a German free flight magazine) is a report on indoor flying with super capacitor and pager motors. A few details.
Models with about 40-54 cm span, weight in order to fly 6,1-7,3g, propeller 143 x 90mm
Powertrain pager motor 30 Ohm, 6mm diameter, used with a 9:1 gear, supercap 10 Farad charged up to 3,4V
Flight times 5-6 minutes

Sources for material: www.didel.com for gear train and motors, www.conrad.de for greencaps.

Urs

PS: I took the liberty to add this coment to this topic even if not perfectly related to it. But I feel there is not much info about cap power around, so it may be helpful for somebody.
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raggedflyer
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« Reply #22 on: January 01, 2015, 01:12:49 PM »

Covering material

My first laser cut depron models were covered with Solarfim SoLite, which is an excellent product but weighs ~20 - 25g/m2 and is available in clear and colours. The coloured films are heavier than clear. For my original all balsa fuselage / depron wing models it is very suitable but over time and as I have learnt through experience by trial and error how to lighten the designs SoLite is no longer appropriate because of weight and (high) shrink rate. The weight is due to the film gauge, material type and the adhesive coating all over. I note that Solite is also listed as being polypropylene, which is a useful clue.

I fly with some fellows that have far greater indoor experience and they use OS film but in the UK it is ~£29 for 20m, so not a sensible choice for me at this stage. My immediate need is satisfied by my particular source of ‘Bag film’ although I would like to establish exactly what that material is. As I said, my ‘Bag film’ weighs ~4g/m2 and 10 layers measure ~ 0.06mm which equates to ~ 60 microns (~0.002”) for a single film layer. That equates to ~0.2g covering for a model of this size.

Aerofoil section

Almost without exception I have used flat sections for the Tailplane and Fin / Rudder and profiled sections for the wings.

I have used both curved under-cambered sections and Jedelsky sections. My current preference is for the Jedelsky section because it seems quicker to make and is probably stiffer. On some designs I have included a 2mm wide x 1/32” thick main spar between the front and rear Jedelsky parts or a 2 x 0.5mm CF spar on the RC version. Some designs have included a shaped 2 x 1/16” balsa leading edge but this seems unnecessary for indoor use.

However, most recent designs have no spar but I have used ribs to keep the aerofoil shape, which also makes the wing stiffer than a flat sheet. Ribs have been either curved arcs ~2-3mm wide, or full height but lightened laser cut ribs from 1/32” light balsa, or more recently full height 2mm depron skeleton ribs which are also laser cut and lightened.

My technique for making the curved aerofoil is to roll the depron underside with a kitchen rolling pin to gradually manipulate a curve. In this case I pre-form the curve, then add the covering (the curvature can be rolled onto the covering film). Then re-form the curve again and carefully shrink the film and re-curve yet again until satisfied. The Jedelsky wing is therefore simpler to form and cover, as the surfaces are flat but angled to each other. In either case each panel is built to form the wing section, then covered as an individual panel. The panels are then joined to give the dihedral. 

With practice both methods work very well and the end result seems oddly stable for a designs and techniques which give the impression of being quite flexible. For instance the trim rarely changes between flying sessions.

Dihedral

Until recently all my designs used normal Dihedral with a centre join. A useful attribute of laser cutting is that the root chord can be shaped (curved or obtuse angled) to provide accurate dihedral. No sanding, cutting or jigging and measuring is necessary and since the wing panels are joined with UHU-Por is not really practical anyway.

Where I have used V-Tail construction a single angled cut is made across the component with a sharp scalpel to form the dihedral angle. I include alignment marks on the laser cut panel for this to be done accurately.

I made one recent variant with detachable wing panels and 2 piece V-Tail so the model could be packed in a small box for air flight. The dihedral angles are set by thin piano wire joininers.

On the latest iyi – SC design I have tried Polyhedral (angles as described in the E20 thread) again laser cutting both joins and assembled with no jigging and had an accurate outcome.
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« Reply #23 on: January 01, 2015, 05:36:21 PM »

Urs

Thank you for your contribution. Very much appreciated. I visited the Didel web page many times and took as many info I could from there, but here there is a bit of restraint about importing, even small items. So I prefer to look for what it could do the job and is available locally.

Raggedflyer

Many thanks again for taking the time to explain your labour so extensively. Very much appreciated too. Interesting work in the evolution of your designs and techniques. Fantastic material; hope you keep posting your work.

Very best regards.

Julio
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« Reply #24 on: January 01, 2015, 09:17:26 PM »

Julio,

I think that you have already received some very good advice from raggedflyer and Urs.

I try for about 16-in span, a 7-mm pager motor from BSD Micro RC, direct drive for a TriTurbo 65-mm prop, and all up weight less than 14g. A geared drive, particularly with high gear ratio like Urs mentioned above should be better if the gearbox is light since the geared system can drive a larger, slower RPM, and more efficient prop. He also recommended a geared 6-mm diameter motor and a lighter plane.

I use tiny connectors SIL connectors and no switch, simply plugging the second two wires together to fly. This saves a little weight.

Some other links here on HPA:

http://www.hippocketaeronautics.com/hpa_forum/index.php?topic=16701.0

An Indoor No-Cal powered by capacitor

http://www.hippocketaeronautics.com/hpa_forum/index.php?topic=11797.0

Chuck Markos indoor capacitor powered event proposed for Science Olympiad students

Fred Rash



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