Galahad Build Blog, IanN

[IanN]

Its the Galahad for me

It was the basic and follow on trainer of choice amongst the r/c fraternity at the club where I flew c/l in my teens in the mid 70s. There were never less than two or three at the field on Sundays, and quite often up to six.

 

It can't be described as pretty but with that angular, almost agricultural, fuselage and the considerable dihedral (5" under each tip) it is certainly distinctive.

 

So, 35 plus years since they were (for me) a common sight, I guess its about time to see one fly again.....

 

 

 

[kc]

I have just noticed there is a long article by Alex Whittaker about building the Galahad in RCME Jan 2005. His version weighed 2 pound 11 oz with an Enya 25SS

[John Privett]

Ian, my second model (following a Tyro Major) was a Galahad - also in the mid-70's. I halved the dihedral on mine and fitted strip ailerons. The same Enya .19 that had powered my Tyro Major powered the Galahad too.

 

I'll be watching this build with interest!

[Biggles' Elder Brother - Moderator]

Well done Ian - you've got the first build blog off to a start!

 

BEB

[IanN]

KC, yes, I did vaguely remember there being an earlier RCM&E article, though I'd lost track of it. I'll dig that out now I know which issue and year

 

John, I'll be building with full dihedral, for rudder/ele/throttle only. Not because I'm a purist, n.b. - far from it - its just that's how they all flew at my old club so I fancy having a crack at doing it that way and seeing how I get on

 

BEB, I trust this is merely the first of many for this mass build

 

I have a couple of engine options in mind, both in the ballpark of what's mentioned above. Actually, it's the engine end of the aeroplane that's giving me the one and only pause for thought that I have re this build. I'll upload a couple of pics of the plan later and explain...

[Biggles' Elder Brother - Moderator]

Posted by IanN on 02/11/2011 20:50:56:

 

John, I'll be building with full dihedral, for rudder/ele/throttle only. Not because I'm a purist, n.b. - far from it - its just that's how they all flew at my old club so I fancy having a crack at doing it that way and seeing how I get on

 

 

Part of the inspiration for this was when I was on holiday and bought a little three channel Piper Cub. I'd never flown a 3-channel model before and I was surprised by two things;

 

1. How much fun it was to fly

 

2. How difficult it was to do an even halfway passable roll!

 

I had a good time with that model and that got me thinking about building 3 cahnnel vintage model - so I too plan to build my Elf 3-channel - not for purist reasons, but just because it'll be fun to fly like that!

 

BEB

[IanN]

I have 3 engines that between them are contenders both for the Galahad and for one other still tbc vintage build. PAW 19 TBR, O.S. 25LA and an ASP 21 with a diesel conversion head. All three should be more than capable, though the ASP hasn't run yet so its an unknown quantity.

 

I may want to swap these engines round in the model so rather than go for the modern simplification of installing a ply firewall and a moulded mount, I'm going to stick with the engine mount as originally designed - a flat plate mounted on beech bearers

 

The only oddity is that the mount plate seems unusually short. The engine cutout as shown is just 35mm deep, whereas my engine options are all c60mm from backplate to rear of the prop driver. That will mean the prop sticking out a good inch in front of the fus. Maybe the original was designed around an unusually short shafted engine?

 

So, the first decision made re the build is to lengthen the mount plate to enable the engine to sit back a little further in the fus than shown on the plan. That in turn moves te tank back a little, and also the half fus former immediately behind the tank.

 

All simple stuff, and balance won't be an issue - there's barnloads of room to move the r/c gear round in

[IanN]

The next q is slightly more taxing. Given that I want to change engines, the obvious "easy" way to do this will be simply to swap mounting plates over. However, the angled front upper fus sides block access to the fixings

 

So, it looks like I need to either

 

- devise a removable top fairing, or

 

- use captive nuts in the top of the mount plates and insert bolts from underrneath the beech bearers, which will necessitate doing away with or cutting into the 3/8" inner cowl cheeks

 

Still considering those options. The main thing is that I want to preserve the original appearance

Edited By IanN on 03/11/2011 12:44:45

[Biggles' Elder Brother - Moderator]

Can't the engine mounting plate slide in and out from the front on "runners"? If so you could mount a back plate on the mounting plate that butted up against a beam or partial firewall and simply bolted in. Its a bit elaborate but it might help you to achieve engine interchanability without spoiling the external appearance. Just a thought.

 

BEB

[kc]

The Whittaker article may help you with the engine plate idea as he too wanted to use different engines. He used an aluminium plate so maybe he tapped it for bolts from underneath. Allen head bolts and holes underneath to take a long allen driver?

But maybe you could put several sets of holes in 1 plate to take all the engines, so you leave the same plate in for all engines?

 

He also mentioned an intended future RCME article by Paul Strawson on fitting ailerons.

[IanN]

Cheers, chaps. Nothing ruled out, all these ideas are under consideration. I realy must dig out that old article

 

I'm pretty sure the Strawsonized Galahad never made it to publication. I'm building rudder / ele / throttle but who knows, an aileron wing (as also mentioned by John above) could be an addition at some future time.

 

For the moment though I'll be building and flying as originally designed, just for the fun of it

[IanN]

Been down to the shed to check on balsa stocks. I think I have enough

 

Will start cutting tomorrow

 

[Pete B]

I reckon you could just about build Kon-Tiki II from that stock, Ian.........

Pete

[IanN]

And still have a bit left over....

 

I've dug out Alex Whittaker's 2005 Galahad review (thanks again KC for referencing that). A full 5 pages, its far more comprehensive and in depth than I had remembered

 

It also confirms a couple of my queries. Firstly, mag photos show that the prop does indeed stick out the front quite a bit

 

Maybe not overly excessive, but I'm going to go with my first instinct and move the engine back a little

[kc]

Presumably he didn't let the motor stick out to improve the looks he probably did it to get the balance right! 

Maybe extend the balsa rather than move the engine back which might mean adding lead?  My way would be to make the top cowl removeable and allow the chance to make a short or long cowl to suit whatever engine is fitted.

Edited By kc on 04/11/2011 14:51:07

[IanN]

You might think so, but nope, it appears not. AW's article states it was nose heavy and he had to move the radio battery right back under the servos to achieve balance

 

As per the earlier posts, its just a very short motor mounting plate. I'm guessing the original used a relatively short shaft engine, or a smaller one. The article does state 1.5-2.5cc originally recommended, though back in the day that would have been for free flight or single channel. It would obviously fly on that, but would most likely be a "summer evening" type device on that power.

 

I think a .19/20, going up to a .25 (as used by AW), but moved back slightly in the airframe to bring the rear of the prop driver back to the nose, will be about right for 3 channel general sports hackery

 

 

 

 

 

 

[kc]

Making the top cowl removeable and held on with those little powerful magnets ( from BRC etc ) might solve the bolt access problem.

[IanN]

I think that's exactly what I'm going to do. It will also give better tank access.

 

If built as shown below, you'd need to remove the engine if the tank needed any maintenance

 

A removable upper fairing will give tank access, facilitate engine swaps, and make any maintenance at the field easier all round.

 

I'll probably fashion that "on the hoof" as the fus build progresses. Initial thoughts are to locate it with a couple of short wire or dowel pegs then, as you suggest, use small magnets to hold it firmly in place (I have a stick of those somewhere)

[Biggles' Elder Brother - Moderator]

Maplins do some small but incredibly strong rare earth magnets - not silly money either considering what they are.

 

BEB

Edited By Biggles' Elder Brother - Moderator on 04/11/2011 18:41:15

[John E ( Puffin Models )]

I bought a Galahad in the 80s, and flew it quite a lot. The down side was that the dihedral had been reduced, and it would have been far better with the designed dihedral.

 

The old OS Max .15 was more than enough power for a very positive climb rate with what aerobatics it would do - and that was with full size radio.

 

HTH,

 

John

[IanN]

Thanks, John, that's useful info re the power required. I have an OS15LA and a PAW 2.49 so will add those to the list of possibles

 

Re the dihedral, do you happen to remember how much yours had been reduced by?

[John E ( Puffin Models )]

Ian,

 

Sorry about the late response.

 

The two engines you have would be perfect.

 

From memory the dihedral was taken to what looked normal, and probably about half the designed dihedral. For some reason low wing and biplane rudder/elevator models seem to need more dihedral than high wing models to roll well (no logic to that at all), so I would absolutely stick to the designed dihedral for a R/E model if I do one myself - reduce the dihedral and suffer the resulting slower roll rate.

 

Perhaps I need to do one!

 

John

[John Emms 1]

So, a few years later!

Last week I became the proud owner of a Ben Buckle Galahad kit. I have to say the plan is first rate, and the kit contents look good (on lifting the lid). The dining table has an ElectriCub 2 on it at the moment, and the Galahad is way down the building queue, but may just jump the queue!

After my first Galahad experience in the 80s, this one will have the correct dihedral, and be electric powered. The original OS 15 gave very good performance, and I am looking at comparable electric power. I know what I would need for .049, .25, .40, .60, .90, 120, and even 40cc equivalent power, but I never sorted out a direct replacement for a .15! I am guessing around 65W x 3lb for 200W would be sensible.

I have 2 BNIB Astro 035G (175W on 2S 3300 with 11x6), I also have a BNIB Astro 15G for 3S (maximum of 250W on 3S), or I could build in a 36mm clamp mount to take a range of 500 and 600 size motors, both 2S and 3S.

Other questions for me: the clamp mount could go on the original design engine mounting plate, or I could redesign the nose to be a "real" electric model with the motor being fitted behind a front motor mounting plate. And, is the model small enough to use the wing as a battery hatch, or do I make the canopy and front deck removeable as a battery hatch? Experience tells me that if I make things too complex, or too impractical, I lose interest!

There is a local Galahad that was running around 400W (Mega 22/30/3E with 11x7) until I gave the owner a smaller prop! Playing with ideas at the moment, but it could become reality pretty quickly!