New Products Flash Sale
Thread Tools
Old Oct 16, 2009, 04:35 PM
MCarlton is offline
Find More Posts by MCarlton
Registered User
Discussion

Designing for storms - or - "throwing design concepts to see if one sticks"


As I sit here, with a 40-50mph wind blasting against my windows, I have the urge to design something specifically for flying in these stormy winds.

The slope I fly off is not a brick lifting super slope, but it is a near vertical sea cliff face of around 200ft (70m) which does a pretty good job (albeit with awful "rotor")

I was initially contemplating something akin to a Jart or Rodent, but I suspect I may not have enough slope to really benefit from the high energy, high loading of that type of model.

So here's my idea, to be built around 55" span with an MH32 or similar section.

Blue foam wing, balsa covered, glassed, with a carbon I beam spar.

Ply/Balsa fuselage, all glassed, solid balsa tail etc.

Last edited by MCarlton; Oct 17, 2009 at 06:13 PM.
Sign up now
to remove ads between posts
Old Oct 16, 2009, 04:50 PM
screamin' eagle is offline
Find More Posts by screamin' eagle
R/C Chronic
screamin' eagle's Avatar
My Jart was about 45 oz, and it flew very comfortably (and fast) in big winds on pretty average hills. One local hill is only about 100' high, and in 35 mph winds, the Jart was very comfy.
Old Oct 16, 2009, 04:52 PM
Antonsoarer is offline
Find More Posts by Antonsoarer
Long to be flyin'
Antonsoarer's Avatar
Nice design, a bit like the old Ridge Racer. What makes it particularly suitable for stormy conditions on a cliff site with an awful rotor?
Old Oct 16, 2009, 05:00 PM
screamin' eagle is offline
Find More Posts by screamin' eagle
R/C Chronic
screamin' eagle's Avatar
On the foil, you may want to go with something thinned, or one of the Don Ayers foils the guys use at Fermin. A standard thickness MH32 may be prone to difficulty in blustery conditions.
Old Oct 16, 2009, 05:07 PM
Phil.Taylor is offline
Find More Posts by Phil.Taylor
Phil.T-tailer
Phil.Taylor's Avatar
Hope there's room for ballast in there - or are you gonna do extra heavy glass?
its the wing loading you need to design for - around 20oz/sq.ft should be fine for 60+mph (well, its worked for me) - Fermin sleds go 30+oz/sq.ft
why not just ballast up whatever other plane(s) you've got?
Phil.
Old Oct 16, 2009, 05:08 PM
MCarlton is offline
Find More Posts by MCarlton
Registered User
Quote:
What makes it particularly suitable for stormy conditions on a cliff site with an awful rotor?
Naff all really, just playing with the design while I work out the details really.

I guess MH32 might be a bit "lifty" so perhaps thinner and lower camber might work.

[IMG]why not just ballast up whatever other plane(s) you've got?[/IMG]

Well, I'm a bit short of slope models at the moment, I've got a Talon and a PMP Sierra Mk2. I did have a PMP Stiletto, but it died. The Sierra doesn't like ballast very much, the most I could squeeze in last winter took the loading up to around 20oz/ft2, but it was a pig at that loading, couldn't really get it shifting fast enough.

I was planning on having the space under the wing for ballast, but to be honest, I'm not quite sure what to do, I'm just bouncing ideas around.

Best models I have flown in big winds so far have been an old Obelix, and the PMP Stiletto (which, sadly, is no longer available).

So rather than buy a kit, I thought I'd design my own.
Last edited by MCarlton; Oct 16, 2009 at 05:14 PM.
Old Oct 16, 2009, 06:20 PM
screamin' eagle is offline
Find More Posts by screamin' eagle
R/C Chronic
screamin' eagle's Avatar
I think you're on the right track trying the build the weight into strength. The trouble I've had flying ballasted models in big wind is that the models are neither designed for the big wind nor the additional weight. That makes landing (which is frequently harder at many sites when the wind is stronger) even more of a challenge.
Old Oct 17, 2009, 12:21 AM
slopemeno is online now
Find More Posts by slopemeno
this space for rent
slopemeno's Avatar
Can't go wrong with a Jart. BillO's weighed something ungodly light, like around 35 ounces, so there's no reason it can't be done.
Old Oct 17, 2009, 12:35 AM
Mark Wood is offline
Find More Posts by Mark Wood
characters welcome!
Mark Wood's Avatar
The 60" Jarteron I recently acquired weighs 60 ounces and flies a 300' cliff with 20mph winds like a dream.
No reason your site wouldn't produce great lift for something along those lines.

mw
Old Oct 17, 2009, 07:40 AM
Alex.Schweig is offline
Find More Posts by Alex.Schweig
Composites Kid
Alex.Schweig's Avatar
My JART came out at exactly 40oz.

Considering that I put two large patches of kevlar in the wind saddle area, stuffed the nose with chopped fiber, set in the wing joiner tube in the wings and the fuselage using thickened epoxy and chopped glass, used thick aluminum tubes and a solid steel joiner, and made my fuselage out of three layers of 6oz glass with a fourth layer in the nose, apart from using heavy seam tape to join both sides....

I'd reckon it's quite easy to get a JART at 30-35oz, if you try to save weight.

-Alex
Old Oct 17, 2009, 11:32 AM
Elmer is offline
Find More Posts by Elmer
racing fool
Elmer's Avatar
Quote:
Originally Posted by MCarlton
40-50mph wind blasting against my windows,

near vertical sea cliff face of around 200ft
Sounds like brick lifting conditions to me.
Old Oct 17, 2009, 01:38 PM
DT56 is offline
Find More Posts by DT56
Registered User
Quote:
Originally Posted by MCarlton
Naff all really, just playing with the design while I work out the details really.

I guess MH32 might be a bit "lifty" so perhaps thinner and lower camber might work.

[IMG]why not just ballast up whatever other plane(s) you've got?[/IMG]

Well, I'm a bit short of slope models at the moment, I've got a Talon and a PMP Sierra Mk2. I did have a PMP Stiletto, but it died. The Sierra doesn't like ballast very much, the most I could squeeze in last winter took the loading up to around 20oz/ft2, but it was a pig at that loading, couldn't really get it shifting fast enough.

I was planning on having the space under the wing for ballast, but to be honest, I'm not quite sure what to do, I'm just bouncing ideas around.

Best models I have flown in big winds so far have been an old Obelix, and the PMP Stiletto (which, sadly, is no longer available).

So rather than buy a kit, I thought I'd design my own.
Since you've flown the Obelix, how about a version with new thin airfoils for the center section and wings?
Old Oct 17, 2009, 02:54 PM
MCarlton is offline
Find More Posts by MCarlton
Registered User
Good thinking DT56, its something I thought about doing a while back. Just had a play about with the basic concept.



Perhaps one of the DA sections, or maybe something like MH22 with a smidge of reflex on the ailerons.
Old Oct 17, 2009, 02:59 PM
DT56 is offline
Find More Posts by DT56
Registered User
Quote:
Originally Posted by MCarlton
Good thinking DT56, its something I thought about doing a while back. Just had a play about with the basic concept.



Perhaps one of the DA sections, or maybe something like MH22 with a smidge of reflex on the ailerons.

Old Oct 17, 2009, 06:12 PM
MCarlton is offline
Find More Posts by MCarlton
Registered User
I'm going a bit mad with concept ideas here, so I took the design above in a slightly different direction, for no other reason than the notion that a seperate tail would allow me to use a different section (the "obelix" idea would probably need a neutral CmO?) and that I happen to rather like twin booms.

So, this is the final design, which is to be built at an unspecified date. I suspect that on the day it is finished, we will be inundated with 6 months of light winds...



Looking at the nose, I appear to be developing a PNF...


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Prep designing for future B-52 build wartoy Foamies (Scratchbuilt) 7 Sep 23, 2008 06:00 PM
Question Designing for side slipping rcav8r2 Modeling Science 5 Aug 11, 2007 07:51 AM
Discussion Designing for Real Flight Deluxe Frankenator Simulators 1 Jul 22, 2007 04:30 PM