Jump to content

Own-design epp depron jet


kevin wild
 Share

Recommended Posts

Advert


Hi Kevin,
 
that's a cool model mate - very nice indeed. Don't forget to tell us how she goes.
 
While I'm on, welcome to the forum. Its a pretty friendly place and you can find all sorts of info and advice - no matter how experienced we are we can all use a bit of help now and then. So don't hesitate to ask if you're looking for data or advice on some issue.
 
If you have time drop in at the Pitts Cafe this is a thread with no topic so you can talk about whatever you want, post a music video or just enjoy the chat.
 
Also take a look here where you will find useful stuff on how to use the various gadgets and facilities on the forum, things like: how to link to other sites, how to post pictures and videos etc.
 
As Tom says it is helpful if you can fill in few details about your modelling experience in your profile and make it public. Its not compulsary, but it does mean that when folks are answering your posts they have an idea of the level you're at - it avoids sessions of "teaching your grandmother to suck eggs!"
 
Hope you enjoy your time on here and once more - welcome on board.
 
BEB
Link to comment
Share on other sites

well it flew
 
It never ends well when a post starts that way does it

I started with a safe c of g at about 12 percent Mac, range checked it and off she went like a scalded cat
 
I climbed to hight and throttled back, i felt i was holding the nose up far too much, the c of g was very nose heavy, now here's the problem do you come in fast with elevator authority or slow ?
 
i tried slow and it just sank, it was a controlled landing but heavy, with the field very muddy and exposed servos on the underside it stopped dead on contact, yep it ripped a servo out, well not the whole servo just the top half of it, the bottom half is still glued in lol
 
it'll be the weekend now before i get a replacement and it'll be next week before i have a chance to try again with a more rearward c of g, i might move the servos up top too

Link to comment
Share on other sites

HI
 
on closer inspection the servo was ok, it had just pulled the bottom of the casing off, i gave it a good check over, tested it with a load and all was ok
 
i spent last night moving the servos to the upper wing surface and then put a bit of paint on it
 
with the battery moved backward 10mm it was off to the common
 
much better this time, i had a good 10min fly getting used to it and trimming it out and then landed, it still sank a bit on landing and i noticed the elevons were up by about 5 degrees
 
i moved the battery back another 10mm and with another battery tried again, i had to trim the nose back down a bit but it was better again
 
it's quite fast on full throttle, I spent most the time at just under half i reckon, the roll rate is fast enough for me but not mental, i was dabbing a bit of down in as she went inverted because the nose was dropping slightly, loops need full power and are pretty big i'd say about 80 foot dia, i haven't tried inverted yet
 
on the 3rd flight i decided to try hi rates, the increased elevator was nice but the roll was too twitchy for me, i climbed to hight, throttled back and held in full up, she slowed to a snails pace and just sank like a delta should, no wing tipping at all
 
one thing i've noticed is that she climbes (swoops) under full throttle, is it the c of g still too far forward ? i will try moving it back a bit more next time
 
i'm pleased with the way it flies, i will try a bit of inverted next time too
canopy painted white and a bit of black behind the nose
 

Link to comment
Share on other sites

kevin
Well built and flown.
It is quite natural for a plane to want to climb as the power is added.
As its speeds up its natural stability will try to keep the plane flying at the same speed so it climbs.
The normal remedy is to set the thrust line of the motor such that as the thrust increases it also produces a nose down pitch to compensate.
With a tail mounted pusher you need to add some up thrust.
Delta wings tend to be quite sensitive in pitch so you may find it difficult to keep a natural neutral trim at all speed and power settings.
A degree of climb with power is reasonable. One thing you don't really want is a full power nose down trim at slow speed when close to the round!
 
Keep posting

Edited By Simon Chaddock on 17/02/2011 21:54:09

Link to comment
Share on other sites

 
 
Sounded like a good idea at the time !!
 
no i haven't broken my plane, i was browsing the modelflying forum and came across a thread with video, one of the posts had a "brilliant" idea for doing your own video while flying
 
no not one handed flying, just tie the camera around your neck and away you go
 
lol i should have known it wouldn't have worked
 
out of the 3min of video i managed before the camera battery died i think the jet is in frame for about 7seconds, that's 14 shots of it whizzing across the screen as i tiny black triangle
 
I've uploaded it to youtube and edited all the rubbish out lol
 
if you're realy bored and like whizzy little black triangles then hre it is
 

Edited By kevin wild on 18/02/2011 15:52:59

Edited By kevin wild on 18/02/2011 15:53:40

Edited By kevin wild on 18/02/2011 15:54:07

Link to comment
Share on other sites

  • 2 months later...
Thanks
 
it scares the poop out of me every time i fly it, think i'm getting too old for small fast models
 
 
kev
Link to comment
Share on other sites

  • 5 months later...

Hi

the lower wing sheet is now 6mm depron. all the ribs are notched and self locate in the correct position




the 8mm spars are then glued in and this pulls the wing skin into shape
the depron spars and false leading edge can then be added


on the old version the epp fins glued straight on to the top wing sheet. I've gone for fin supports this time within the wing. I did manage to snap one off in the garage once

the fuselage and canopy were solid epp on Mk1. it's all built up for Mk2.
the canopy has a 6mm frame


side sheeting is then added and sanded flat along the top


the top sheet is then glued on and its ready to sand

I've drawn up some sanding templates to make sure i don't over sand it and make it too thin

   




 

Edited By kevin wild on 17/10/2011 15:21:00

Link to comment
Share on other sites

The fins on Mk1 were 10mm epp and not rigid enough to support the stresses of rudders so a 3mm balsa spine is sandwiched between 2 3mm skins on Mk2  


after the balsa is glued to the one sheet fury Ca hinges are glued to the depron. the second sheet is then glued on and when dry the edges are pinched in to give a symmetrical section. the top and leading edges are simply sanded round
 

 

the fins will be glued in after the top 3mm skin is in place



Edited By kevin wild on 17/10/2011 15:33:13

Link to comment
Share on other sites

The fuselage is now built up. it's a minimum of 12mm wall thickness and feels very solid so I'm hoping it'll take a few knocks


a simple box section with alignment tabs is first


then the skins are added one at a time. because the battery will be larger and further back it's left the nose empty. I'm going to put my Rx up front well away from the esc but it could be buried in the wing to save extending all the servo wires

bottom skin and upper former in place

top skin added

the outer skins are then glued on

ready to sand






Link to comment
Share on other sites

I've rough sanded the fuselage. need to make some templates to finish it. it's a round section along the length so not too difficult to get it looking good


trial fit. the nose locates on three tenons and should auto align itself


the tenons are shown here. one large one at the bottom and small ones either side






 

Link to comment
Share on other sites

HI
I've spent most of today tinkering with the rudder torque rod setup. with the rudder linkages hidden in the wing it seems a pity to mount the elevon servos as i did on the original. do any of you have experience of using the torque bar method on elevons ?
 
I've seen this setup on youtube demonstrated but wonder if it's practical for my elevons
I've drawn it up and the servo will just fit under the wing skin if a move it in between the spars
 

the rear carbon spar has been hidden in the image and the elevon top skin made transparent. the servo (dark red) turns a torque rod (pink) that runs freely in a ply box in the elevon. the amount of bend in the torque bar is set to give the correct amount of movement
 
questions ????
 
is this setup good enough for a high speed model ?
can a nice slop free movement be achieved ?
how thick does the torque bar need to be ?
 
rudder setup


Edited By kevin wild on 23/10/2011 22:02:49

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...