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Jul 05, 2019, 07:26 AM
Ken's CAD Models
dz1sfb's Avatar
Thread OP
Quote:
Originally Posted by ruff1
Spitfire is ready...

Build info:
Motor: Suppo BL2208/12
ESC: 10 Amp Heads Up
Battery: GoolRC 900 mah 2S 25C
Prop: 7035
AUW: 10.5 oz
CG: 2.2 inches per the BF109 instructions

Max power: 46 watts @ 7.1 amps - this works out to 70 watts per pound. With wing cubic loading at 9.9 hopefully that will work. Dr. Kiwi shows thrust around the AUW.

I had to put .8 oz in the nose to get the CG right.
Brother, your going to want a 7x6 prop to get the watts per lb up, as well as the desired air speed. That motor is rated up to 16A, which means your only pulling 44% of the power it is capable of producing.

Ken
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Jul 06, 2019, 04:06 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Thanks for the advice. I did some earlier testing, and guess I got confused with the prop I was testing and the results. Those tests had me believing the 7x6 was too much prop with the 10 Amp ESC. I tested a Master Airscrew 7x6, today and it produced 68 watts at 9.6 amps. The connectors got warm but nothing to worry about.

With the AUW of 10.5 oz, that puts me at 105 watts per pound. How does that sound?
Jul 07, 2019, 02:52 PM
Ken's CAD Models
dz1sfb's Avatar
Thread OP
Quote:
Originally Posted by ruff1
Thanks for the advice. I did some earlier testing, and guess I got confused with the prop I was testing and the results. Those tests had me believing the 7x6 was too much prop with the 10 Amp ESC. I tested a Master Airscrew 7x6, today and it produced 68 watts at 9.6 amps. The connectors got warm but nothing to worry about.

With the AUW of 10.5 oz, that puts me at 105 watts per pound. How does that sound?
The 2208 motor is capable of drawing 16A, so it is quite possible to overload a 10A esc.

APC style props seem to give the best bite with the wider blade profile.

Anything over 100 watts per lb. is good. However, loading the motor to its capacity is how to get the most out of any motor without added weight. You should be able to squeeze 130 watts out of that motor, giving you up to 198 watts per lb. You've got a lot of untapped energy.

Ken
Jul 07, 2019, 08:09 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Thanks for the feedback. I'll go with what I have for now.
Jul 27, 2019, 06:32 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Ken,

Maidened today; after dialing in some expo and reducing control surface throws it flew very well. Test pilot really liked the way it rolled, looped and handled inverted flight. A bit too much airplane for me right now, I'll get some buddy box time which should help.

Thanks for a great design sir!
Aug 13, 2019, 07:42 PM
Registered User
Captain Dunsel's Avatar
I have a TBF on the assembly jig, with a Blackburn Skua waiting for the TBF to get out of the jig so it can have it's turn.

Once the Skua is tested (and assuming it survives the test), I'll post the plans. The TBF (from Ken's TBM plan), will have an XT-500 driving the rudder.

I'm looking at some pre-war Skua schemes -- all silver, with roundels on the wing tops. For the TBF, I'd like to put it in star-and-meatball, 1942 colors (but without rudder stripes, if possible!).

CD
Aug 14, 2019, 08:12 AM
Jer. 29:11
jeffsch's Avatar
@Captain Dunsel, the jig is fantastic! Looking forward to seeing your Skua.
Aug 15, 2019, 02:52 PM
Registered User
Captain Dunsel's Avatar
Thank you, Jeffsch, the Frankenjig has been evolving for quite a few years!

Got the control surfaces hinged, the horns glued in, and what I hope will be the final spackling done. Need to finish sand, then paint -- have to go to Wal-Mart and check out the paint selection!

BTW, the fuse & bits in the background are from a box-fuselage SE-5a I started a few weeks ago. It's on hold whilst I finish the two profile jobs for NEAT 2019.

CD
Sep 02, 2019, 06:51 PM
Registered User
Captain Dunsel's Avatar
Been away, camping, so it's taken a long time to get these done. Add in that these are the first models I've done out of bare foam (and my first use of an airbrush)...and they're pretty rough.

I was shocked when I found Sharpie ink bleeding through water-based paint. As far as I knew, Sharpies were alcohol-based, impervious to acrylic (water-based, I thought) paints. So, I wrote notes, parts ID's, etc., on the foam, expecting the paint to cover my writing -- only to find the letters bleeding through. It took coats of 'White-Out' correction ink to finally seal the Sharpie stains.

So far, the Skua's had one, short flight. I had far too much aileron throw in it, and was barely able to bring down in one piece (broke the wing, though). It's been fixed and the controls have been dialed down to about 40%.

No flights on the TBF, yet. Between weather and hectic schedules (prepping for our departure for NEAT this weekend), we haven't had time to take either one back out.

CD
Sep 02, 2019, 07:31 PM
Registered User
Quote:
Originally Posted by Captain Dunsel
Been away, camping, so it's taken a long time to get these done. Add in that these are the first models I've done out of bare foam (and my first use of an airbrush)...and they're pretty rough.

I was shocked when I found Sharpie ink bleeding through water-based paint. As far as I knew, Sharpies were alcohol-based, impervious to acrylic (water-based, I thought) paints. So, I wrote notes, parts ID's, etc., on the foam, expecting the paint to cover my writing -- only to find the letters bleeding through. It took coats of 'White-Out' correction ink to finally seal the Sharpie stains.

So far, the Skua's had one, short flight. I had far too much aileron throw in it, and was barely able to bring down in one piece (broke the wing, though). It's been fixed and the controls have been dialed down to about 40%.

No flights on the TBF, yet. Between weather and hectic schedules (prepping for our departure for NEAT this weekend), we haven't had time to take either one back out.

CD
Great job
Sep 03, 2019, 08:40 PM
Registered User
Captain Dunsel's Avatar
Thank you, BCool.

Got out to re-maiden the Skua and maiden the TBF.

First, the Skua's ESC went POOF when I connected the battery -- I guess the maiden flight crash did more damage than I thought.

Then the TBF's motor stud loosened up after about 10 seconds of flight, with the model coming down in the soy beans alongside the runway. The 'canopy' got a bit bashed and the half-teaspoon scoop came off, but that was the extent of the damage.

Re-assembled the motor, torqued everything down, and made a second go at it. This time all went well for about 30 seconds; loops, rolls, Cuban 8's, all were okay.

Then the buzzing started. After a hurried landing, I realized the paper canopy was coming off, with the buzzing being it flapping in the wind. Otherwise, the flight was uneventful.

Back home, I swapped my LAST 10 amp HK ESC for the smoked one in the Skua. Problem is, the winds are due to increase, so I don't see getting in another test before we leave on Saturday. <Sigh>.

CD
Sep 08, 2019, 01:54 PM
Registered User
Captain Dunsel's Avatar
Re-maidened the Skua and got a longer flight...by about 2 seconds! I think the wing (and/or the ailerons) was flexing with aileron input. Put in right roll, and it would roll to the right - then to the left. I intentionally put it down before I could reach bystanders (not that I had to try hard to bring it down). This time, the damage is fatal.

I'm not going to pursue the Skua, at least not in its present size. I will look at scaling it up to about 360-400 squares and adding LG. I may still do a KfM airfoil, but I'll wait on it.

Meanwhile, the TBF flies fine, with more than enough power on the 1300 Kv Turnigy motor and a 3S350 pack. That one's a keeper!

CD
Sep 11, 2019, 09:54 AM
Registered User
TenDouble's Avatar

2 new BF109s


My son and I built decided to build a couple of the VLF BF109s. The Monster version is mine, and is a standard build using DTF. The Redbull plane is my sons and I added an inch to the tip chord and 1/2 inch to the profile of the vertical stabilizer. He really out did me with the paint. The equipment is identical in both planes:

Emax CF2805 with an EMP 6x5
2s 850mah (gives about 7 min of normal flying...not WOT all the time)
tp 9 gram servo for ailerons
power up 5 gram servo on elevator
monster plane auw is 8 oz
redbull plane auw is 8.5 oz

Both planes are fast and have out of sight vertical. The redbull plane slows down better, and feels more locked in. We have been having a blast flying them.
Yesterday, 10:42 PM
Ken's CAD Models
dz1sfb's Avatar
Thread OP
Quote:
Originally Posted by TenDouble
My son and I built decided to build a couple of the VLF BF109s. The Monster version is mine, and is a standard build using DTF. The Redbull plane is my sons and I added an inch to the tip chord and 1/2 inch to the profile of the vertical stabilizer. He really out did me with the paint. The equipment is identical in both planes:

Emax CF2805 with an EMP 6x5
2s 850mah (gives about 7 min of normal flying...not WOT all the time)
tp 9 gram servo for ailerons
power up 5 gram servo on elevator
monster plane auw is 8 oz
redbull plane auw is 8.5 oz

Both planes are fast and have out of sight vertical. The redbull plane slows down better, and feels more locked in. We have been having a blast flying them.
Very nicely done!

Ken


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