A Mini funjet - type thing ( full fuse ) - RC Groups
Thread Tools
Aug 22, 2010, 12:35 PM
Lawn dart pilot/builder
Prime_8's Avatar
Build Log

A Mini funjet - type thing ( full fuse )

A Mini funjet - type thing ( full fuse )

from post #83
the larger forward swept idea.

updated pic:

foil created lift but made too much drag & mass so :

Mayday 27's 2x size box version in wicked flight !
Prime Jet8 flight envelope (2 min 58 sec)


well sort of , using built up dollar store foam .
too much inspiration floating arround forums .. LOL

and a small bit of ply in nose for those rather energetic landings.

still not sure if i will use a 2nd layer for wing and sand a foil into it , or use a modified KF?
any how she glides ok now, touch nose heavy . flys like a dart.

the bumps on wings are because i may make her a twin pusher , depending on what micro gear i have.
updated plans . instructions are through thread rite now as it is a living project. LOL
plans updated: https://www.rcgroups.com/forums/show...2&postcount=22
full rez plans for 8.5 x 11 paper ( attachments get shrunk )
Last edited by Prime_8; Oct 06, 2010 at 08:06 PM.
Sign up now
to remove ads between posts
Aug 22, 2010, 01:01 PM
Storm Runner guy
Slider2732's Avatar
Oh it's more than a 'thing' already

I'd go with a KFm type of section, though you may not need anything else other than what you have.
Personally had great successes with very careful sanding on the Dollar Tree board. Doubled up it means a lot more sanding work, for areas of thickness that a KFm would give by being much simpler. KFm's allow the air to work as though the foil was sanded really eh.
It's thick enough to make a difference at higher flight speeds for the size (around 25mph+). Lots of reflex sanded in underneath and give the air time to arrive at the front, time to leave at the back. Sanding very shallow on the LE underneath can help neutralise bad tendencies on this sort of shape...as can washout, especially at the trailing edge tips.
It can be considered as a plank and as a more traditional flying wing with a nose on.

What sort of gear is going in it, or pencilled in for it as possibilities ?
Envisaged AUW ?
Wingspan ?

Aug 22, 2010, 05:51 PM
Lawn dart pilot/builder
Prime_8's Avatar
will get stats shorty .

the gear will be freshly harvested radio n guts of a airhogs jet set f18 . it uses thrus vectoring .
if i can keep it below the 40g the jet set was the small motors will be fine .
it has a 1s 150mah cell . and charger is also the controller.
i like the f18 , as i don;t have to mod the TX to allow for 0 throttle truning .. LOL

:: i'm not sur ei understand about the under side & LE of wing you mentiond?
I'm new to micros . i have built many slimer big things . and only getting back into it as electrics have power now. LOL

more pics soon .
Aug 22, 2010, 10:02 PM
Lawn dart pilot/builder
Prime_8's Avatar
well so far she flys wicked fast ..
50% T = flat no climb or decent.

anything above 50% = climb

below 40% is fast down. LOL ( have to work on that )

steering is good. she flys dead striat with trim at 0 ( good thing)
TV is touchy i have to pulse it , untill she is at speed or flat sping city . LOL

she has no dihedral . ( i may give her some , and some sort of touch of up elevator )

but i will hold off inwing mod till i understand more.

i may try taping a simple KF on . LOL
of a AUW is 27g ! yay , proly 1g to add in closing fuse bottom & possibly paint & WBPU sealant. LOL
- and more foam to come off in fuse shaping / sanding left to do .
WS = ~12 inches

original AH f18 was 40g , and i can say she is way faster than the f18
Last edited by Prime_8; Aug 22, 2010 at 10:08 PM.
Aug 22, 2010, 11:08 PM
Storm Runner guy
Slider2732's Avatar
Not a bad weight for the power system...that being the main thing, always build lighter than the plane it came from.

Seems like you have the wing pretty well sorted out at this point, without extra pieces of KF or doubling up.

On flying wing shapes, the underneath is about as important as the top, in my opinion. What I was saying, was about sanding in a more gradual curve on the bottom of the leading edge than the top. You then need to have the back edge rise from underneath toward the wing top surface, to make a sharp point at the trailing edge of the wing. Might need some elevon deflection even with doing that, but it seems you have a 50% straight ahead throttle working already

Turns can benefit for differential thrust, with the washout I was on about. Sanding the underneath of the wings near the tips upward. Also, in some cases, bending the very rear edge corners upward helps for a lot less side to side wobble or yaw as it's known. That can also help your thrust vectoring control and halt the over steering that leads to spins.
Any pitching up and down in flight, porpoising, is normally corrected by moving the CG forward..it's climbing, stalling, climbing, stalling and so giving rise to that condition if it develops.

All in all though, it's going well isn't it
Aug 23, 2010, 12:47 AM
Lawn dart pilot/builder
Prime_8's Avatar
Thanks for help.

Cooll i think i get that .. good thing cause i would have sanded it like my titan or my sport plane.

I know that micros are touchy .
(i wish i had a AR6400 but that is for x-mass i think this year ..LOL )

so for now just re using my AH guts , and that means TV only . lol

but update on flight ... if i don't use teh steering buttons but rather steer with the trim knob it works awsome . ( i smell a controlle rmod comming )
the trim finly ballences T for each motor , and as this rig is well ballenced it actualy steers like a D/R at high speed .. like my other jet set V1 i modified .

all the AH stuff is prone to porpoising , but if you get the up E correct and manage your T you can controll level flight very well .

i expect this beast to fly like this one of mine but way faster .

- see my V1 AH jet set all modded up .. controller got 2 diodes & cnanded the cunnards.
AH Jet Set - Moded all over - charge time flyer (1 min 40 sec)

:: done .
Canopy sanded into shape.
- Blue sharpie ( ran in foam ,
had to white wash with acrillic )
- AUW 26g - RTF
- using tape to close last bit of

now i'm curious to test your sanding treatments .
i would love to see a sample cross setion of a FJ wing chord.
hmm image hunt.... LOL

:: & i made upper wing doubler to test KFm simple. it could add stabillity at speed.
i will tape it in place during test tomarrow if weather is good.
Last edited by Prime_8; Aug 23, 2010 at 02:23 AM.
Aug 23, 2010, 12:22 PM
Lawn dart pilot/builder
Prime_8's Avatar
well , I taped a KFm like to the top. only had to tape LE due to shape to hold it on.

it flys wel , way more stable , but way slower, it seems to me. butit is windy and not a whole lot of room in my back yard.

as she is now i can fly with or without the foil.

i added a small clear elevator to rear of fuse . that helped big time , in finding CG and then setting the up E % for thrust climb.
Aug 23, 2010, 05:05 PM
Lawn dart pilot/builder
Prime_8's Avatar

more done and some more testing

more done and some more testing finished for the day.

she flys better but tad slower with KFm on .

any how some late sun pics.
Aug 24, 2010, 05:09 AM
Registered User
starscream4002's Avatar
nice build! good luck on trimming her out

Aug 24, 2010, 03:41 PM
Lawn dart pilot/builder
Prime_8's Avatar
thanks took some funny trimming video today .

I kept the lawn darting in .

in the end with very carfull examination of the otehr AH jets i have i saw they all have 2 -3deg of down thrust on pushers that will act lilke up elevator.

she flew way better when i did that .
teh dove tail unde rhas a slight up e as well but mainly it helps pull her out of flat spins.

i tride to put some diheadral , but wing resists it. my have to so some surgury , because she flew way better when i hade 4+ deg of D.
any how video cooking now. it's funny.
if i had mor etime today i would have been at field with bigger planes. LOL
but i run out of room in my back yard for this one . LOL all my plane sare too fast for propper BY flight . LOL

on vimeo .. but still converting ... i will be at work so i will post it now , so i may still be converting.
Mini FunJet thing , trimming flights (0 min 42 sec)
Last edited by Prime_8; Aug 24, 2010 at 03:48 PM.
Aug 24, 2010, 06:14 PM
Build it again, Sam!
Harpye's Avatar
I would place the motors closer by the fuse and install them a bit inverted...

would make the model less sesitive against too much differences in thrust....
Aug 24, 2010, 07:21 PM
Lawn dart pilot/builder
Prime_8's Avatar
i was just thinking , closer. LOL they went on in same distance form fuse as they had on f18.
and well it was prone to flat spins too at low speed .

I can't wait to take her up to the field.

i also found leaving the battery bay open was causing huge drag and a nose down effect.
soon as i coverd it with tape it was way better.

I will prolly move motors closer in & i'm nosure what you mean by inverted ?
but i know if i pigeon toe em in a bit it will also soften thier yaw effect.
and they point down a bit so at 50% + T she will climb .
man i wish the TV was proportional.. but i think moving motros in shoudl do it .
just have to un-do the hot glue . . LOL
should be good.
& mod TX to give me a knob for 2nd/ sub trim as the trim works like proportional TV. very well actualy. ( it reduces T to one or the other , while stick adds ~5% T in TV )

any rate this AH guts is pleanty fast enough for this small fry. I may upgrad eteh lipo to a slightly bigger 1s , as she seems to like nose weight . i tested with a few nickels and was good.

but i can't wait to get her to the field and WOT while she has some recovery height.

rite now i'm try to figure a non deastructive way to add diheadral , it only stays fo r afew min . and i cant do the bake it in , in the car as it has been too cold in last few days.

+ sanding the TE of the wing up from bottom helped a bit. but mainly i have to use a hard turn to drop her when she gets near my trees. LOL

not in that video was a flight that she went up and shot a bit vert on a glitch, it was funny as hell , she came down and flew down the path back of my yard.

she is tough as hell especialy with wing doublers ( KFm ) on .
i may try a test with foil off to compare with agian. should be faster , but a touch less stable at slow speed . LOL

i would love to make one 2x this sise, and put a small BL&ESC and AR6400. but that will have to wait for fundage $$ LOL.
Last edited by Prime_8; Aug 24, 2010 at 07:27 PM.
Aug 24, 2010, 10:50 PM
Storm Runner guy
Slider2732's Avatar
Yep, Harpye means exactly as you describe, to pidgeon toe. The thrust will have a V effect, spreading out more over the wing surface than straight back. Only a couple of degrees or so, but TV planes are much more manageable with it.

What seems to happen here in your vid, would be a classic case of trying wing fences. A sometimes used trick, to halt that roll of air over the wings and that drops off the sides. The net effect of what i'm seeing, is that the plane enters a turn and can't come out of it...as you say, it can fly with the trim control. So it's WAY sensitive about losing air over the flying surfaces.
Wing fences are just a couple of strips of foam, positioned at about 50% wingspan on each side and running to 50% back, starting just a tiny amount forward of the leading edge. Height need only be about 4mm or so. What you'd be doing, is stopping that roll of air. At a point in your turns, the air is moving across the aircraft and not from front to back...the wing fences stop that increasingly violent loss of lift.

Best bit, it's just 2 pieces of foam, that can be taken right back off again if they do nothing.
Here's the Wiki entry for them: http://en.wikipedia.org/wiki/Wing_fence
Here's a pic of wing fences, from my builds and just to show what they look like
Last edited by Slider2732; Aug 24, 2010 at 10:57 PM.
Aug 24, 2010, 11:13 PM
Lawn dart pilot/builder
Prime_8's Avatar
hmm very cool
i should make a set for KFm and without .
I'm not 100% sold the KFm is doing mor ethan even drag .
( to be fair i have not snaded the lower wing LE only the KFm foil LE )

also had a funny thought, if i put a curve in the KFm near tips to the drag effect is more , or less ? lol
sort of like ?duckerons? help flying wings.

because thisis just a flying wing with a big nose. LOL

:: so move motors in = to 1 prop radius , add a few deg of pigeon toe. during that , nad make a set of fences .

now that dove tail thing , cut the flat spins down by 70% ( or only 3 flat spins per 10 flights )
also note some of those hard over's are from me having to stop before getting to close to foam-avore trees that have foam tearing and eating bark. LOL
they can be like hitting 60 grit sand paper LOL
hmm if weather in noce this am , i will take her up to field before kids get there.
now i also need to give mt T-Boomer one more flight befor i move onto an new version of it , so i have 4 planes now competing for flight test time .. LOL

but this one is way fun . I may still make that right stick a pot hooked to trim on TX and put 2 push buttons at sides .. LOL
could be good. sub trim & input + 2 turn boosts LOL
- and other TX mod. LOL

well i'm stuck at work for 5 more hrs. Now i have some food for thought
big thanks for help guys.

i cant wait till i have a ar6400 , and a small esc and brushless , then my crazy creations will have way better control. but still it's hard to pass-up AH's whole planes as kit parts in one bo for 30$ TX/RX Lipo charger .. if you like TV .

:: after looking at your pic , i sure know what to do with my bronco v2.1 's gear if it don't fly well tomarrow on it's maiden .
Aug 24, 2010, 11:42 PM
Storm Runner guy
Slider2732's Avatar
There's no harm in sanding out some of that KFm section at the tips...after all, it's just sat there doing nothing of benefit at the end of the wing.
We need to always look at how the air strikes the surfaces, reacts with them and leaves.
A blunt ended KFm section will be ok for a high wing trainer (Mackey like to do that squared off ends thing), but on a flying wing shape we lose the elevator function at the back of the wing, by giving the air nothing to work with. So, it stalls at the wing tips, rather than stalls in the middle to bring the nose down.
Own trials have included chopping down the amount of KF airfoil, from full thickness again of the wing, to 1/3rd. I find they can give too much lift ! Speed goes down, mushing starts and the whole thing sits in the air for 35 minutes like a helicopter lol. Nah, just joking, but there's a lot of room to play with such a simple yet efficient concept.
Looking at 3 views of aircraft (billion of them in the scratchbuilt foamies section) we always see a thick middle and tapered wing tips...a blunted outer wingtip CAN work, in the case of say the Assassin flying wing, but generally there's that taper.
So, sorry to ramble about the KFm section, just some observations

Best wishes for the morning tests

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Build Log Nice stunt plane (full fuse Cap.. extra...) type platform kneekolaas Foamies (Scratchbuilt) 10 Apr 14, 2015 03:07 PM
Build Log Tachyon - Foam Mini-Hotliner (full fuse, full wings) chara Foamies (Scratchbuilt) 91 Nov 22, 2014 09:13 PM
For Sale full fuse eflite tribute $65 hornetflyer Aircraft - Electric - Airplanes (FS/W) 1 Jul 28, 2010 12:49 PM
Question A styrofoam, full fuse Cessna-type - where to find? magic612 Free Flight 3 Jun 16, 2009 03:50 PM
Discussion which type of foam for a scratch built full fuse 2m ASG-29E Yellow Baron Foamies (Scratchbuilt) 0 Nov 30, 2008 10:32 AM