Minishark, Twinshark build experiment...2500w/lb++ goal! - RC Groups
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Jul 12, 2017, 04:35 PM
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Minishark, Twinshark build experiment...2500w/lb++ goal!


I am in awe of the current, 1500w@11.2-13 oz prototype, so time to make a twin for even more power to weight.
This new tech combined with light and stiff composite construction is evolving quickly for me.
I will go into the build details on both another 28.5", and 35" twin as it occurs..

The 35" will feature two of the 1500w systems, and should only be about 16-19 oz with a full 3000 watts!... with an up to 8s , 4000w potential. UPDATE.. 18-22.5OZ TESTED.
I am currently testing systems over 60k rpm with no issues.
I plan to set a benchmark, if not some kind of record for power to weight for prop, winged aircraft.
I will elaborate in the future, but all this has resulted in serious potential for more fun.
The current single showcases the lightest weight combined with the highest static burst power using 6s quad racing gear that hooks up quick using 4-5" bullnose props that are always ready for turbine smooth 50k ++ rpm and beyond.
2kg thrust +, x2, counter rotating off the line sounds tasty @ 35", 16-19 oz twin
Stay tuned....

UPDATE** 34"TWIN FLOWN WITH GREAT SUCESS!**

Here is an early 27.5" test, having to run a 1.2 second delay on throttle to work. (Now faster @ .5 second)
15-25 mph winds, fast pass @3:00.
Launch @ only 45% throttle.
Short bursts give 5 minutes flight on only 700mah/870!!
May 28, 2017 (5 min 16 sec)


Here is the "light" 6s version flying 3 minutes on 277 mah out a 370 pack!!
7.4 oz, 14a static @ 41,000 rpm on HQ 4x4".
Obviously unloads in air, and notice the quick slow down-to landing..
Electra Shark (3 min 23 sec)
Last edited by MikeRx; Nov 09, 2017 at 09:24 PM.
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Jul 13, 2017, 07:47 AM
Wait .... what ?
NickDe's Avatar
Saw your video of you flying this plane and it is amazing. Any idea if u are going to make plans or sell kits for it ?
Nick
Jul 13, 2017, 09:09 AM
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Quote:
Originally Posted by NickDe
Saw your video of you flying this plane and it is amazing. Any idea if u are going to make plans or sell kits for it ?
Nick
Thanks! I will tag that video here.
Look out for the TWIN!
After I shake down a few prototypes and make any needed changes, I will make a file for plans.
A kit is not likely unless I can find a way to cut wing cores with airfoil in an economical way, and/or come up with a mass production techniques that make sense.
The construction is rather simple, but the wing gets a high level of sanding, both to produce the core, and sanding the skins down to the .5mm trailing edge.
I will try to illustrate and describe what is involed, starting with the TWIN, that will maiden in the next week.
These only take me about 20 hours or less to complete, with paint.
Last edited by MikeRx; Jul 15, 2017 at 09:50 PM.
Jul 13, 2017, 02:22 PM
Wait .... what ?
NickDe's Avatar
I'll definitely be watching. Small fast planes are fun and so easy to transport (unlike my bigger 3D planes) and give an awesome adrenaline rush to fly. I'd like to get a really fast pylon plane but am trying to keep my modeling budget under control. My wife always says "Is that another airplane?" so I explain that several small planes only equals one big plane .
Nick
Jul 13, 2017, 05:09 PM
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Quote:
Originally Posted by NickDe
I'll definitely be watching. Small fast planes are fun and so easy to transport (unlike my bigger 3D planes) and give an awesome adrenaline rush to fly. I'd like to get a really fast pylon plane but am trying to keep my modeling budget under control. My wife always says "Is that another airplane?" so I explain that several small planes only equals one big plane .
Nick
Hey thanks Nick!

Well I just got back from the hobby shop with enough building materials for 2 aircraft, and plenty of change from a $100 bill.
The motors are $20, I bought 4 slightly used esc for $72 shipped. Quality servos under 10.
HV BEC for $10, etc.. batteries are $25-50.
Case is $140, but that could be justified easily.
Look closely, it actually has two inside in the pic..
Your gonna win with the wife here if you can fit in the hours, and easily source the wood.
I live in Dallas TX with 6 locations within one hour drive that have large balsa selection, including some with depron.
Figure 15-25+ hrs each.
Last edited by MikeRx; Jul 13, 2017 at 06:37 PM.
Jul 13, 2017, 06:03 PM
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Shall we begin?


Zoom around these pics and you will see what is involved, including exact dimensions...
6mm depron cores are drawn in half, then matched.
1/16"x6x36 bottom skin
1/32"x6x36 top
1/8" hard for both stab, fuse parts.
3/32 medium for fuse sides.
1/4" triangle stock
1/8 hard ply firewall.
Light, 3/4 oz cloth. 1/2 oz for upper surfaces and vertical stab optional.
Z poxy resin
.5x3mm and .8mmx3 carbon strip.
Quality C/A hinges. (But no c/a here..)
1/32" ply for control horns. (Gets glassed also.)
150 grit on a 12" T-bar does the dirty work for me.
Micro pushrod set works great.
I use heavier 1mm music for the ail.
(I double Z all my ends, no hardware)
Finishing abrasives.
Both thin and medium foam safe c/a.

It took me one hour to draw/match/cut these cores..
They need to be further trued and match sanded more next..
I will do this, then create the rough airfoil now...
Last edited by MikeRx; Jul 15, 2017 at 09:53 PM.
Jul 13, 2017, 07:06 PM
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Gear!!


One can use whatever they choose from a vast array of available racing quad gear.
I chose the highest performace combined with light weight.
Motor F80 2500kv
https://m.banggood.com/T-Motor-F80-2...p-1112679.html
Bench run over 60k rpm and 70a burst.

Esc F45
http://www.getfpv.com/tiger-motor-f-...s-w-dshot.html
Will burst to 70a 6s, or 60a on 8s.

BEC
http://www.getfpv.com/electronics/5v...regulator.html
This will work on 8s.

Everything runs reliably and very smooth.

HQ 4x4.5 or 4.5x4.5 bullnose props are smooth and amazing, with 5 or 6" options.

TATU 650 mah 75-150c, (3sx2) $25
TP 870 mah 70-140, " " $50
Tatu 1400 6s 75-150c $27
TATU BATTERIES ARE AMAZING FOR THE PRICE.
The 650 takes gives 60a bursts and asks if you want more.
The TP 870 can handle the wildest, wide open minute you will ever want to have...
(The video flies for 5 minutes on 700 mah using 2-4 second bursts.)
Think faster than a 52", 4lb, QM racer (over 200mph), but half the size, less than a quarter of the weight, with more than twice the thrust to weight.


Im gonna hammer that 1400 with 120 amp bursts in the twin, which will likely go 100mph on less than 20a.
Last edited by MikeRx; Nov 09, 2017 at 08:12 PM.
Jul 13, 2017, 07:41 PM
Wait .... what ?
NickDe's Avatar
There's so much great small electronic gear, motors, and batteries now because of quads. Seems like they really push what can be done with electric motors and the price is right. I always felt like the gear in quads would be awesome in planes and you are definitely proving it. Will be anxious to see how that twin works out. I'm sure it won't be slow .
Nick
Jul 15, 2017, 10:47 AM
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Cores..


The airfoil is formed roughly by sanding the top core only as shown.
It is best to sand with T bar flat on a surface.
I will finish the shape of the core once this is glued to the skin, making the curves very even.

The cores are glued together when they are perfectly matched with special attention to the trailing edge.. it must be straight.
The final airfoil is sanded out of the skins.
Next to glue bottom skin/carbon..
Last edited by MikeRx; Jul 15, 2017 at 12:09 PM.
Jul 15, 2017, 11:56 AM
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Skins..


Make outline of core on skin.
I mixed 10ml Z poxy and spread a line on the wood where the 18" spar is laid, 2" rear of front/center.
The rest of the resin is spread evenly on the flat bottom core, then pressed onto wood.
This appears to be enough resin for this 34", or a bit much for the 27.5".
The top spar in pic shows location of bottom spar, now laminated in place.
Since everything is flat, no elaborate pressing is needed, but some weight is needed for at least 3-4 hours from here..
Last edited by MikeRx; Jul 15, 2017 at 12:23 PM.
Jul 15, 2017, 02:12 PM
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Final core sanding...


After the bottom has set finsh sanding the core to a .5mm lip at the T.E.
This is where the carbon goes later..
It should be a gradual slope working back from a high spot about 30% rearward from the l.e.
Work slow and check often for even results..
Jul 15, 2017, 03:24 PM
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Trailing edge carbon


Here is where the .5x3mm carbon really finds it's use!!
I use medium , foam safe ca generously, smoothing out with finger and wax paper.
(One can use any glue of choice, but I choose the faster option here)
MAKE SURE IT IS POSTIONED CORRECT.
Notice aileron the lines.. this is where you will "spot" your aileron to cut out later, measured at 10 and 5/8" from center.
I am using a thicker .8 mm x 3 top spar, channeled in. Now to glue top skin..
Last edited by MikeRx; Jul 25, 2017 at 01:51 PM.
Jul 15, 2017, 03:26 PM
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Quote:
Originally Posted by MikeRx
1/16"x6x36 bottom skin
1/32"x6x36 top
Just a point here, from a structural standpoint you want the heavier skin on top to deal with the compression loads. I understand that may be a major pain when trying to get it to conform to the airfoil shape, but structurally it is the better way.

I love the thread. Small, cheap and fast are great things for my modeling budget...


Mark
Jul 15, 2017, 03:30 PM
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Quote:
Originally Posted by mmattock
Just a point here, from a structural standpoint you want the heavier skin on top to deal with the compression loads. I understand that may be a major pain when trying to get it to conform to the airfoil shape, but structurally it is the better way.

I love the thread. Small, cheap and fast are great things for my modeling budget...


Mark
Nice observation..
I use the thicker bottom to allow more material for final airfoil.. it is perfectly flat before sanding.
The top spar is stiffer and will be swimming in a channel of resin to adress this.
The final glass really makes it strong.
Yea.. pain to conform thicker skin..
Last edited by MikeRx; Jul 15, 2017 at 03:38 PM.
Jul 15, 2017, 03:35 PM
Registered User
Quote:
Originally Posted by MikeRx
Nice observation..
The top spar is stiffer and will be swimming in a channel of resin to adress this.
The final glass really makes it strong.
Yea.. pain to conform thicker skin..
Since you are using the carbon for strength could you get away with 1/32" balsa for the bottom skin as well? Or has that been tried with some nasty results?


Mark


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