Logo
Builders' Plan Gallery  |  Hip Pocket Web Site  |  Contact Forum Admin  |  Contact Global Moderator
January 20, 2019, 08:53:55 PM *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with email, password and session length
 
Home Help Search Login Register
Pages: [1]   Go Down
Print
Author Topic: Horsa-ing around  (Read 761 times)
0 Members and 1 Guest are viewing this topic.
TheLurker
Gold Member
*****

Kudos: 15
Offline Offline

United Kingdom United Kingdom

Posts: 398


Topic starter


Ignore
« on: January 01, 2019, 03:36:28 PM »

Airspeed Horsa.

I like work-horse aircraft and the Airspeed Horsa is one I particularly like.  However, leaving aside 6' plus span RC behemoths, I could find only one plan for a model at the sort of size that I have house-room for, R.V. Base's design for the Dec '43 Aero Modeller with a span of about 22". You can find a copy on outerzone (ID 3798).

The original plan was drawn at half size and having looked it over I thought it would benefit from some simplifications as well as rescaling to a span of about 32" (bungee launching; for the use of) so after a great deal of faffing around with Inkscape, bits of card and likewise pestering of Abl & Jack Plane I now have an untested plan for a 32 1/8" (projected) span approximation to an Airspeed Horsa which (fingers crossed) should be big enough to fly OK (if it flies at all) and well within the 36" limit.

Approximation?  Aye.  This is will very definitely be a scale-ish model. It's more about getting something that flies and looks the part when it's aloft than a concours d'elegance winner.

Untested?  Oh dearie me yes. The plan is quite definitely a work in progress.  There are all sorts of niggles and unknowns to be worked out with this one as we go along.  In fact that's where anything, if there is anything, of interest with this build will lie.  For instance; at the moment I'm not even sure whether or not it will have any sort of undercarriage as my wet finger guesstimate of wing loading for the 22" span indicated it was borderline for a glider without the UC.

One decision has been made and will be adhered to.  In the spirit of kit scale (and to keep weight down) the model will be finished in Al. tissue as MK II (AS. 58) TL472 which was, for a very short period in 1946, silver doped overall.

So ladies and gentlemen you are invited to pull up a seat, grab a snack, pour yourself a drink and watch a disaster unfold, very, very slowly, before your very eyes!

Lurk
Attached files Thumbnail(s):
Horsa-ing around
Horsa-ing around
Horsa-ing around
Logged
Balsa Ace
Gold Member
*****

Kudos: 25
Offline Offline

Canada Canada

Posts: 466


FAC Member



Ignore
« Reply #1 on: January 01, 2019, 03:57:57 PM »

That's a great choice for a very interesting project,Lurk.

Scott
Logged

Hawker Sea Fury FB.11
HMCS Magnificent
VF-871   Royal Canadian Navy
Jasco
Bronze Member
***

Kudos: 1
Offline Offline

United States United States

Posts: 26


Aero ergo Sum



Ignore
« Reply #2 on: January 08, 2019, 07:16:19 PM »

I want to throw my encouragement your way!  Watch a disaster unfold very slowly? Hilarious! My last project stalled just before the final steps in readying for test flights. Alas, she looks good just sitting there.
Dont forget to post plenty of in progress pics. I love seeing other techniques. (Or even the same ones)
Logged

Cutting open my thumbs since 1964.
Ouch
vtdiy
Gold Member
*****

Kudos: 12
Offline Offline

United States United States

Posts: 273




Ignore
« Reply #3 on: January 08, 2019, 08:12:06 PM »

That would be really cool!
Logged
TheLurker
Gold Member
*****

Kudos: 15
Offline Offline

United Kingdom United Kingdom

Posts: 398


Topic starter


Ignore
« Reply #4 on: January 09, 2019, 01:21:12 AM »

Well so far I've managed to cut some of the pieces for the keel, real life, hey ho, and as exciting as I find them I can't believe anyone else would.  Even MrsLurker, who is pretty good at feigning interest in things aeromodelling, was struggling to display anything other than a blank look when presented with these masterpieces as in,  "Hmmm. Yes Dear.  Several bits of oddly shaped balsa.  How very interesting, do tell me more."  However, both progress and disaster will be published as and when.
Logged
vtdiy
Gold Member
*****

Kudos: 12
Offline Offline

United States United States

Posts: 273




Ignore
« Reply #5 on: January 09, 2019, 10:22:42 AM »

Mighty oaks from little acorns......!
Logged
TheLurker
Gold Member
*****

Kudos: 15
Offline Offline

United Kingdom United Kingdom

Posts: 398


Topic starter


Ignore
« Reply #6 on: January 13, 2019, 11:35:50 AM »

Now have the beginnings of a fuselage.  Keel, port frames and side-keel in place. 

Keels are hard balsa. Frames medium.  Longerons are going to be medium.  And that's the next task; cut some 1/16" strip for the longerons and after that set up a jig for bending / steaming them to cope with the after part of the fuselage.

Fairly pleased with the accuracy of the part profiles so far. They do need a bit of fettling, the long one piece side keel in particular, but allowing for my cheap and nasty ink-jet printer's iffy image reproduction and the inevitable blade wobbles when cutting the parts they'll do.

Remember I said it'd be slow?  Not logging hours, but this is about two evening sessions and as well as two long-ish weekend sessions. If you've got something more interesting to do I wouldn't hang around here expecting hourly updates. Smiley

Pics.  Cut parts, test fitting and glued fuselage waiting longerons.
Attached files Thumbnail(s):
Re: Horsa-ing around
Re: Horsa-ing around
Re: Horsa-ing around
Re: Horsa-ing around
Re: Horsa-ing around
Logged
TheLurker
Gold Member
*****

Kudos: 15
Offline Offline

United Kingdom United Kingdom

Posts: 398


Topic starter


Ignore
« Reply #7 on: January 14, 2019, 04:16:44 PM »

Cut some strip this evening and just carried out a test fit.  Unusually for stuff I cut the longerons drop nicely into place, but have turned up the first snag.  One of the lower slots at frame 6 is misaligned, see the attachments.  I thought, for all of 3 femtoseconds,  about cutting new F6s, then about widening the slot and then finally I thought, "Stuff it. It's a test build.  I'll update the plan and part profile and that'll do." Smiley 

It's not quite a disaster as was promised, but at least summat has gone wrong, so you won't be getting your ticket money back. Smiley

Sorry about the soft focus image of the afterpart of the fuselage; the camera lied. It told me it was correctly focused.
Attached files Thumbnail(s):
Re: Horsa-ing around
Re: Horsa-ing around
Logged
vtdiy
Gold Member
*****

Kudos: 12
Offline Offline

United States United States

Posts: 273




Ignore
« Reply #8 on: January 14, 2019, 04:22:48 PM »

Looks like it's coming along nicely, to me.
Logged
bobson
Bronze Member
***

Kudos: 5
Offline Offline

United States United States

Posts: 49



Ignore
« Reply #9 on: January 14, 2019, 04:33:17 PM »

Looks great, nice progress! Maybe you've seen this -- Tom Nallen II built a Horsa a few years ago that is an incredible scale model and flyer. Not sure if it was from the same plans.

https://www.youtube.com/watch?v=S5vZcZ0HUos
Attached files Thumbnail(s):
Re: Horsa-ing around
Logged
TheLurker
Gold Member
*****

Kudos: 15
Offline Offline

United Kingdom United Kingdom

Posts: 398


Topic starter


Ignore
« Reply #10 on: January 15, 2019, 12:59:09 AM »

Looks great, nice progress! Maybe you've seen this -- Tom Nallen II built a Horsa a few years ago that is an incredible scale model and flyer. Not sure if it was from the same plans.
Oh dear. That sets rather a high bar to clear doesn't it? Smiley  That's a lovely piece of work and thanks very much for the link; it shows that I probably won't have to sacrifice the undercarriage to save weight.

I'm probably wrong but I don't think Mr. Nallen's model is from the R.V. Base plan.  The stabilizer seen in the clip has correct square-ish tips, the Base original has very rounded, almost semi-circular, stabilizer tips.  Squaring off the stab. tips was one of a number of minor changes I made when redrawing and resizing it.
Logged
TheLurker
Gold Member
*****

Kudos: 15
Offline Offline

United Kingdom United Kingdom

Posts: 398


Topic starter


Ignore
« Reply #11 on: January 16, 2019, 03:29:22 PM »

Couldn't live with the misaligned longeron at F6 so widened the slot, first one down from the side keel, and packed the gap as per pic and made note (a proper one in the log, in black ink) to go back and revise the part profiles for the F6 pair.

Port half built, lifted it off the board this evening.  Sternpost pulled a tiny pit port, but otherwise all seems OK. With luck stbd side keel will correct that.  
Attached files Thumbnail(s):
Re: Horsa-ing around
Re: Horsa-ing around
Logged
DavidJP
Titanium Member
*******

Kudos: 41
Offline Offline

United Kingdom United Kingdom

Posts: 2,593




Ignore
« Reply #12 on: January 18, 2019, 11:56:07 AM »

Nice and neat Lurky. 

I have always fancied doing one of these ranging from slope soarer to a big radio model and now to the little FF job.

As a matter of interest over the years I have concluded that stringers in notches are not essential and so simply laying them on the former can work a little more easily? But I see you are using stringers that are rectangular in section rather than square. 

The other thing I learnt building the KK flying scale models was that it was better to put the stringers on "in the air" to reduce the bus. going out of shape.  But they did not have keels!

I did know a couple of chaps by the way who were in the Glider Pilot Regiment (one built built models too).  Bit daunting when you think they were   disposable - often used only once!!  Pegasus Bridge (as it became known) for example.
Logged
TheLurker
Gold Member
*****

Kudos: 15
Offline Offline

United Kingdom United Kingdom

Posts: 398


Topic starter


Ignore
« Reply #13 on: January 18, 2019, 04:01:39 PM »

Quote from: DavidJP
Nice and neat Lurky. 
So far!  Many a slip twixt cup and lip.

Quote from: DavidJP
...I see you are using stringers that are rectangular in section rather than square. 
Ah. Yes.  That would be because they're, "orl me own work" and I'm not that good with the old balsa stripper. I rather like using notched frames because the strip is held securely on 3 sides rather than butted to it. I expect there's probably no difference in robustness between the two methods, but it's my comfort blanket and I'm not giving it up without a fight. Smiley

Quote from: DavidJP
I did know a couple of chaps by the way who were in the Glider Pilot Regiment...
I'm always extremely impressed by the nerve and bravery of such people.  FWIW this area is stiff with aerodromes that were involved in glider (and other) ops.  Brize was a GCU, Down Ampney, Fairford and a couple of others were all operational fields for glider units.


Quote from: DavidJP
The other thing I learnt building the KK flying scale models was that it was better to put the stringers on "in the air" to reduce the bus. going out of shape.  But they did not have keels!
Yeah, when I was discussing the plan and the build notes I've put together with Abl a month or two back he made much the same point and I expect for skilful builders it's a method that works well, but I'm a ham-handed bodger and would probably break two longerons for every three I fitted.  Hence my use of the half shell and jig approach.  And that gives me a nice excuse to post a couple of pics of the fuselage mounted in its cradle ready for the stbd side which I'll be starting on tomorrow.

Still puzzling / waiting for inspiration to strike about the most robust / lightest way to provide fuselage mounting points for the UC so have deferred that little task for now.
Attached files Thumbnail(s):
Re: Horsa-ing around
Re: Horsa-ing around
Logged
abl
Silver Member
****

Kudos: 11
Offline Offline

United Kingdom United Kingdom

Posts: 228


Andy Blackburn



Ignore
« Reply #14 on: January 18, 2019, 04:59:52 PM »

If you're still looking for an undercarriage solution, my bid would be:
1. Leave off the skid as it doesn't usually appear in photos and its simpler without one
2. Use two bits of wire per side, the ends of which plug into aluminium or brass tubes that are the full width of the fuselage (possibly with 1/8" square cross-members and some gussets):
   a) A V-shaped bit for the bottom two members that plugs into the bottom two tubes, and
   b) A long bit that plugs into the top tube and has the axle on the other end, bound with thin fusewire and soldered where it intersects the apex of the V of part A, using Lurker Industries Large Equipment Division's biggest soldering iron.

You can put a slight bend on the plug-in bits to make an interference fit but it'll still be disassemble-able for transport and should knock-off in the event of a mishap.
Logged
DavidJP
Titanium Member
*******

Kudos: 41
Offline Offline

United Kingdom United Kingdom

Posts: 2,593




Ignore
« Reply #15 on: January 19, 2019, 09:38:17 AM »

Looking at your pictures - particularly of the jig set up - I think you are jolly well entitled to keep your security blanket.  Any prospect of an even slightly untrue fuselage is surely eliminated. And it is far simpler than the old bit of 1/4inch spruce I stick down the fuselage so I may well adopt your method next time.  Take it that there is no fee?
Logged
TheLurker
Gold Member
*****

Kudos: 15
Offline Offline

United Kingdom United Kingdom

Posts: 398


Topic starter


Ignore
« Reply #16 on: January 19, 2019, 02:52:35 PM »

War & Peace alert.  Cup of tea and biscuit required for this one.  Smiley

If you're still looking for an undercarriage solution, my bid would be:
1. Leave off the skid as it doesn't usually appear in photos and its simpler without one
2. Use two bits...
Thanks Abl, my mind (no comments please) was/is running along those lines for the UC, but I'm swithering about putting a length of hard 1/16" above the Al. through tubes or inserting a small patch of infill between the longerons to support said tubes in the manner of a motor peg.  The Parish Idiot, despite noting in the draught build guide that the longeron supporting the through tubes should be hard strip, has used medium.  This is unlikely to survive many landings.  The hard strip approach has the edge at the moment purely on the grounds of simplicity.   The attached explanatory images page shows the Mr. Base's original scheme for the UC wirework. The through wires (which will become tubes) are fixed to the lower longerons.

Fuse wire? Who has fuse wire in the house these days?  May have to unbraid some fine wire. Smiley

As for fitting the skid, that's not really a problem and it shouldn't interfere with the UC. See the attached exp. images page and "cutting" from the plan.  The single central ram variant (MK I, AS.51s) is a piece of cake to deal with and I think I have a fix for the double ram type (MK II AS.58s).   Now, if you were modelling a GCU airframe then you could legitimately lose the skid and have a really natty scheme into the bargain.  By happy coincidence p23 of the Feb. AeroModeller has an example of a GCU scheme for a G.A. Hotspur which is shown as part of Colin Baxter's article on 2-D CAD.  If you haven't got a copy yet your favourite search engine should turn up good examples.  There are some colour publicity photographs showing paratroopers disembarking from GCU machine at Brize Norton somewhere out there.

What might be an issue with the skid is fouling or snagging the tow on launch as my estimated position for the tow hook is quite close to the front of the skid.  Some non-scale remedy may be called for to deal with this, but we'll cross that bridge when (if) it gets as far as flying.

Quote from: DavidJP
... Any prospect of an even slightly untrue fuselage is surely eliminated.   
Ermm, let's not say that until we're done, eh? Smiley

Quote from: DavidJP
I may well adopt your method next time.  Take it that there is no fee?

Fee?  *chortle* Well if you're offering, mine's a pint. The cradle (if it's not obvious) is dead easy.  Some 2" x 1" (or metric equiv.) pine batten from the local DIY barn. Pretty cheap. but choose carefully; some of it can be pretty bendy and we don't want that.  "Lolly" sticks from a "craft" type shop (in the U.K. "The Works" or "HobbyCraft" carry them, but again pick and choose because they too can be bendy.  Bendy is not good.  And finally some map pins from your favourite stationery supplier.  Glue some lolly sticks on the base and ends of two lengths of batten to keep everything aligned.  I drill a couple of holes in the base sticks. It lets me pin the frame to the board so it doesn't skate around.  I likewise drill holes for the map pins in the clamping sticks that hold the keel in place.  Pine is soft enough (just) to take the map pins so it means you can reposition the clamping sticks if needs be as you're working and all component parts can be re-used for subsequent keel builds.


A little more progress today.  Ballast chamber fitted in line with Mr. Base's original design.  This is a contingency measure. I'm hoping that I'll be able to use some sort of ballast tray between the two horizontal nose formers (NF1 & NF2) so that AUW can be kept a smidgen lower.  Remainder of starboard frames being fitted this evening but you know what that looks like so I won't bore you with pictures of that.
Attached files Thumbnail(s):
Re: Horsa-ing around
Re: Horsa-ing around
Re: Horsa-ing around
Re: Horsa-ing around
Re: Horsa-ing around
Re: Horsa-ing around
Logged
TheLurker
Gold Member
*****

Kudos: 15
Offline Offline

United Kingdom United Kingdom

Posts: 398


Topic starter


Ignore
« Reply #17 on: Today at 03:50:47 PM »

I'm pleased to report that the Dept. of Aviation Archaeology at the Lurker Industries Aeroplane Company has made an interesting discovery about the Horsa plan as it is at the moment.

Observant types will have noticed the absence of keel over a significant part of the fuselage top.  I certainly did, but I thought that the wing platform bridging this gap combined with suitably placed gussets would reinstate/provide the necessary vertical stiffness in the centre of the fuselage. Errr.. no.  There are number of possible reasons for this any one or all of which might be contributory factors.

- The plan has been scaled up by just under 50%.  The Longeron count was increased (+2 each side) to allow for this, but 1/16" strip was retained rather than specifying thicker strip.  Various reasons for this not the least being the tight bends required from F5 to the stern post.

- There's a wide gap between F3,F4 and F4, F5.  These gaps are proportionally wider than those drawn on the original because the original plan had them drawn too small for the root / central section ribs.  

- I've used medium rather than hard strip for the longerons.  Still think this was the right thing to do but...

For this build I've introduced some diagonal bracing in the F3/4 and F4/5 bays and it seems to do the trick.  I'm debating whether or not to do the same for bays F5/6 and F3/2 so the remaining longerons are yet to be fitted while I sleep on the problem.

I'll probably revise the plan so that a saddle keel is used, but that will have to wait until I've test flown (oh, you incurable optimist you!) this build to check that the wing incidence is OK because if a top / saddle keel is introduced I intend to rest the wing platform on it. There's not much extra length/weight in the diagonal bracing compared to the proposed additional section of keel and it does mean you can tinker with the built in incidence of the main 'plane, but a full keel is likely to make it an easier airframe to build.

I may increase the bulkhead count as well to reduce the width of the bays.  Bit of a trade of for weight there.  Another problem to ponder in slow time I think. Revisit it when I've got a realistic idea of AUW / wing loading for this one.

The last pic is for fun.  It's my homebrewed "Is the wing platform level and not bowed" tool for testing in temporarily inaccessible locations.

I don't know about you but I think it's rather fun resurrecting sketchy 75 year old plans.  Smiley
Attached files Thumbnail(s):
Re: Horsa-ing around
Re: Horsa-ing around
Re: Horsa-ing around
Re: Horsa-ing around
Re: Horsa-ing around
Logged
DavidJP
Titanium Member
*******

Kudos: 41
Offline Offline

United Kingdom United Kingdom

Posts: 2,593




Ignore
« Reply #18 on: Today at 05:44:00 PM »

Still looking neat! 
Logged
Pages: [1]   Go Up
Print
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines Valid XHTML 1.0! Valid CSS!