Galaxy/Pegasus Hurricane

[payneib]

2 hours ago, Martin Harris - Moderator said:

. What size are you using?

 

3" on 90-120 size electric retracts. It trundled well across my relatively long garden grass, although I'll have to be very careful - that 15" three blade doesn't have a lot of space under it. I'm happy for this to be another "perfect days only" plane - there's plenty of winter hack sport planes to go around. 

[payneib]

2 hours ago, Jon H said:

why does it matter if i ever built one?

...........

Turns out the model is 66 inch and not 60 as i originally thought, and with that in mind the weight is not quite as much of a concern. Its still very over powered

................

Not entirely, but after 18 years in the model industry i have had enough of smart alec comments and will be far less diplomatic when responding now i am just a modeller again. 

It matters because the entire point of the question was to find out information from people who've actually built and/or flown one. If I wanted advice about similar models I'd talk to people flying things like the H9 109, at 64" span, up to 1.25 four stroke/20cc petrol, and a projected weight of 10.25-11.5lbs - one of which already flies at my club, with that engine, at that weight. Unfortunately, despite the great qualities of the Galaxy kits, they appear to be as rare as rocking horse eggs, which is why Pegasus already uses one of my models in their advertising, after I raised the point about lacking information directly to them.

 

Feel free to be as belligerent as you like, but you should expect to be treated the way you treat others. Especially if you put it out before checking what you're talking about. 

[Jon H]

8 hours ago, payneib said:

Feel free to be as belligerent as you like, but you should expect to be treated the way you treat others.

 

The pot calling the kettle black. I was more than happy to assist and was quite happily posting away until you kicked off with your snarky 'throttle moves both ways' comment. So perhaps you should consider the way you speak you people if you do not want the same in return. 

 

If it was in jest and i misunderstood then fair enough, but i do not have much tolerance for snarky nonsense. Especially when the engine you have has a pretty dreadful throttle. 

 

8 hours ago, payneib said:

It matters because the entire point of the question was to find out information from people who've actually built and/or flown one. If I wanted advice about similar models I'd talk to people flying things like the H9 109, at 64" span, up to 1.25 four stroke/20cc petrol, and a projected weight of 10.25-11.5lbs - one of which already flies at my club, with that engine, at that weight. Unfortunately, despite the great qualities of the Galaxy kits, they appear to be as rare as rocking horse eggs, which is why Pegasus already uses one of my models in their advertising, after I raised the point about lacking information directly to them.

 

Ok fair enough, but from my point of view once you have flown a handful of 60 ish inch warbirds you have flown them all. The basics are the same for all of them and the lessons from one easily apply to another. For example the H9 109f is a bit of a porker. It always has been and i do not know why it should end up so heavy and its not really a great yard stick to measure by. Seen in isolation it might look ok and fly alright, but compared to a broader range of similar models it is more of an outlier. 

 

Regarding Galaxy, they were at their peak in the days before the internet and their kits faded from the lime light by the time it came along so information will the sparse. I used to fly a galaxy mustang and it was a good model which flew well on a 150 4 stroke. They are old designs and their age shows in many respects but they do generally fly well once all is said and done. 

[payneib]

32 minutes ago, Jon H said:

 

 I was more than happy to assist and was quite happily posting away 

 

 

So "Yikes!" is what you consider assisting is it?

 

I think I've seen enough of your assistance to know I can ignore it as a matter of routine. 👍

[David Davis]

If I were looking for advice on WW2 warbirds of about 5-6 feet in the wingspan, Jonathan Harper would be the first person I would approach. He is a very experienced builder and flyer of this type of aircraft and until he started his new job he was the development engineer for Laser Engines, a British four-stroke which you may have heard of.

[Martin Harris - Moderator]

Can we draw a line under this please.
 

There will always be differences of opinion on forums but we don’t need to resort to sniping at each other. 
 

While I understand the frustration of seeing repeated advice seemingly ignored, a new poster will be unaware of past advice so perhaps a little more tolerance would avoid this sort of situation. 
 

Please don’t respond to this post (PM me or another mod. if anything is unclear) and let’s return to the subject of sharing information about the Galaxy/Pegasus Hurricane. 

[Martin Harris - Moderator]

Returning to the subject...

 

As mentioned earlier, I bought mine at a swapmeet in early 2003 (looking quite elderly even then) and I've just remembered that on the included plan, it shows torque rod operated strip ailerons.   I see yours has, like mine, scale position inset ailerons and split flaps.  Were these detailed as an option in the build notes or were later plans/kits modified?

 

Anyway, I've removed some lead to bring the CofG back about half an inch from the plan position and reduced the elevator movement.  The grass has been cut today so, fingers crossed, I'll start putting Jon's advice to the test tomorrow...

 

P.S. I see the Pegasus website illustrations show strip ailerons...

Edited April 17 by Martin Harris - Moderator

[Martin Harris - Moderator]

Flight tested today.
 

4 oz. of lead removed from over the engine. CofG 1/2” back from plan position - elevator reduced to plan specified (3/8” up and down) amount. 
 

No apparent reduction in stability (it’s some time since I last flew the model) but still eager to nose over. Grass freshly cut but quite damp and draggy for the little 2” wheels.  Inverted flight required definite push so I’ll be removing more lead. 

[Chris Freeman 3]

The heavier the airframe the less stable the aircraft will be so a more forward  CG will be required. Always hard to put more weight in a heavy airframe. Elevator movement is critical as too much can result in a snap roll. EXPO can work against you on a test flight if the trims are out and you need to say up before trimming. I have always found it best to fly the aircraft to see how it handles as some aircraft can handle excesses better than others. Tomorrow we will be flying a 1/4 scale S6  that the builder never flew as he thought it was too heavy and would not fly. It flew very well when Byron test flew it and the original builder will be with us to see how well it actually flies.

[GrumpyGnome]

6 minutes ago, Chris Freeman 3 said:

The heavier the airframe the less stable the aircraft will be so a more forward  CG will be required. 

Sorry but I don't understand why that should be.......  I'm not saying you're wrong, but I don't see the reason why that should be...

[Chris Freeman 3]

Take 2 airframes, 1 heavy and 1 light and you will see the difference in stability. I once did a kit review for David Boddington and when I had issues with the flight performance of the aircraft which was heavy and then compounded by our thinner air in Johannesburg, David said I should move the CG forward of the recommended position and it did help the flight characteristics. I have done this ever since and had good results. CG is also a personal preference as some pilots do like a twitchy airframe and others do not. Stability at low speed quickly shows if the CG is correct. 

[David Davis]

I would have thought that a heavy model would be more stable because it would be less likely to be blown about in turbulent air than a lighter one.

 

Apparently my Barons are heavier than they should be. I'm hoping for a bit of a breeze in la Coupe Des barons in June! 😏

 

Of course a heavy model with a cg too far to the rear would be a handful!

Edited April 19 by David Davis

[Chris Freeman 3]

 A big difference between a scale aircraft with a higher wing loading than non scale lightly loaded aircraft. Scale or semi - scale aircraft normally have smaller tail surfaces and tapered wings which also has a bearing on the stability. 

[Martin Harris - Moderator]

In this case, we’re looking at a solution for the ground handling difficulties which seem to plague some models - and the Hurricane in particular. 
 

There’s no magic about a CofG position marked on a plan - we rarely know whether the designer has marked it there as a result of practical testing, calculation or even guesswork!  Then we also don’t know whether it’s been chosen by personal preference or with safety in mind. In fact, if the plan shows a CofG range rather than a single point, I’d have more confidence in the designer’s aerodynamics competence. 
 

In this case, I’m carefully conducting a test of combining more rearward positions with reducing elevator movement based on Jon Harper’s experience with similar warbird models.  This may not correspond with full size movements but perhaps scale effects e.g. Reynolds Number, start to become significant on control effectiveness with models of 1/6 or smaller scale?

 

I have also provided a “taxi” switch (non latching) which gives a higher rate for taxying and initial stages of the take-off run. This carries over from pre-experiment times. 

[Nigel R]

1 hour ago, Chris Freeman 3 said:

 A big difference between a scale aircraft with a higher wing loading than non scale lightly loaded aircraft. Scale or semi - scale aircraft normally have smaller tail surfaces and tapered wings which also has a bearing on the stability. 

 

Stability has (possibly) a few meanings.

 

Aerodynamically (we need an aerodynamicist here) I don't believe the characteristics of the airfoil, in terms of CofP movement etc etc, will vary by scale or reynolds. I could be wrong. However - taper, wing loading, tailplane size, neither factor in the airfoil parameters.

 

At an airframe level, a tapered wing will exhibit more tip stall at lower scale due to behaviour at lower reynolds. I guess that could be 'stability'. How the tip stall problem is countered is a different question I guess.

 

 

[Chris Freeman 3]

It is very easy to over complicate this discussion. My son and I normally test fly our models in Primer and once happy with the flight performance we paint the aircraft. It can be surprising to see how just the weight of the paint can affect the flight performance. Another example is if you fly at sea level and then fly the same aircraft at a higher altitude airfield. Many of the scale competitors at the world champs in held in South Africa were surprised at the difference in performance or lack of it, Thinner air is effectively the equivalent of a heavier aircraft.    

[Chris Freeman 3]

David Boddington wrote this in AMI August 1996

[GrumpyGnome]

@Chris Freeman 3 It was this sentence of yours that I was querying.... "The heavier the airframe the less stable the aircraft will be so a more forward  CG will be required".

 

Surely the mass of an aircraft is irrelevant in determining it's balance point ?  You may feel more comfortable flying it with a more forward balance point, to avoid stalls (which will occur at a higher airspeed) but that's the only, tenuous, argument I can see.  AFAIK, when our slope chums add ballast to their models, they want an unaffected balance point, just more mass.....

 

More than happy to be educated.

[GrumpyGnome]

20 minutes ago, Chris Freeman 3 said:

David Boddington wrote this in AMI August 1996

 

Lighter aircraft fly slower, but not necessarily 'better' - in the normal UK windy conditions, some models often stay at home because they don't have the mass to cope with the wind comfortably.  As with all things in our hobby, it's a compromise.

[leccyflyer]

Given the article format, maybe Bodders meant that they flew better in knife edge?

[GrumpyGnome]

Maybe.....

[Nigel R]

1 hour ago, Chris Freeman 3 said:

David Boddington wrote this in AMI August 1996

 

But that doesn't mention or address stability. It does mention "high speed stall", as in, a heavy model stalls at a higher speed, but that's a different subject to stability. The stall angle is not affected by CG position.

 

As GG says, happy to be educated.

 

 

[Nigel R]

Some thoughts / my tuppence.

 

It strikes me that one of the problem scale models have is that scale models don't operate on scale grass.

 

We can't fix the grass problem, so we might want to angle the gear forward "a bit" to counter that.

 

I'd guess that can be accommodated by different pintle angles and whatnot on a scale model, all whilst keeping the scale wheel well position.

 

The CG shouldn't need to be much different to the full size. Warbirds were not designed to be inherently unstable (unlike a fly by wire jet).

 

 

[Jon H]

ill add my 2p as well. 

 

I can see that if you had 2 identical models, but one was a brick, it might be less stable than its lighter mate when flown at the same speed as it would need a greater aoa, but generally weight is not a factor as long as the model is within the range of weights appropriate for its size. 

 

On reynolds and all that...ehhh its pretty much meaningless unless we are building exact scale replicas with identical wing sections etc. As we dont tend to do that, just forget it and move on. 

 

As a side note, most model warbirds tend to have over size tails to 'improve stability'. I have a big problem with this as making the tail bigger also makes the elevator bigger, and thus more effective. This makes an already sensitive model more sensitive leading to excess nose weight to tame the beast. 

 

I believe this larger tail idea is a hangover from the free flight days when the bigger tail would have probably been an asset. However, now we have our dumb thumbs on the controls the static stability of the aircraft is less important as we are able to correct deviations we do not like. 

 

With this in mind i built my little hurricane with a scale (or more scale) tail on it and i have no stability problems with it, and my elevator movements are still very small. 

 

 

So take that modelling folk lore. I advocate scale tails and rearward c/g in the pursuit of model warbird bliss. Oh and i cant be bothered with side or down thrust either. Mount it straight and use the tall waggly thing on the back. 

 

[payneib]

On 17/04/2024 at 22:40, Martin Harris - Moderator said:

Returning to the subject...

 

As mentioned earlier, I bought mine at a swapmeet in early 2003 (looking quite elderly even then) and I've just remembered that on the included plan, it shows torque rod operated strip ailerons.   I see yours has, like mine, scale position inset ailerons and split flaps.  Were these detailed as an option in the build notes or were later plans/kits modified?

 

 

 

P.S. I see the Pegasus website illustrations show strip ailerons...

No, there's no option on the kit for tip ailerons and flaps, but I did some actual measurements of some diagrams, eyeballed some full size Hurricanes at Duxford and Shuttleworth, and came up with cutting a step in to the TE by ~6mm (the thickness of the TE wood cap) to make the tip ailerons deeper, and used the stock torque rods to do split flaps.