Plan builds using balsa, how heavy are yours?

[Gary Manuel]

I've just been out walking the dog and whilst doing so, I had another thought about the choice between adding nose weight versus putting a larger engine in. My thought process went something like this:-

 

Start with the assumption that you have a model with a perfectly sized engine to give you the flight performance you want. The only problem is that it's tail heavy and requires a significant amount of weight adding to the nose to give you the balance you need. You add a few ounces of lead to the nose and the balance is now spot on.

 

Let's now consider what effect this has on the model. The model is now heavier than it was, so it will need more lift to overcome the extra weight and get the model airborne. In order to generate more lift, the model will need more speed. Once the model has more speed, it will also have more drag. In order to overcome the extra drag, it will need more thrust. In order to have more thrust, it will need a bigger engine. This is of course, unless the original engine has enough power to provide the additional thrust required for flight. If it does, then the engine wasn't perfectly sized for the model, it was already oversized, so our initial assumption was wrong.

 

Alternatively, rather than adding the lead, use a heavier, more powerful engine in order to provide the additional  thrust which is required as a direct consequence of adding extra weight.

 

In summary, more power is needed from the engine regardless of what form the added weight takes, so it may as well be a bigger engine.

 

Not trying to score points here or suggest that my preference is better than anyone else's. Just expressing my thought process and what I see as science based principles. Carry on adding lead if you wish, but at least understand the effect it has on the model.

 

[Jon H]

Gary, cant disagree, its just that i sometimes see people fitting 120's where a 70 or 80 would do just because they dont want to add a bit of lead and that is clearly a bit mental. You are right about AUW though and the model's weight needs to suit what it is. A WWII fighter should not be too light as it wont fly right, equally if its too heavy it will be like a manhole cover (im looking at you topflight spitfire) and, as you say, a pig to land. 

 

You point about running engines flat out is valid, its why i recommend 180's and not 120's or 150's for 1/4 inch tigermoths and stampes. Half throttle takeoff, plenty of power for a loop etc. That said, my Sea fury is scale fast at around 60-70% throttle on a flyby as well so i consider that to be fine. 

 

Geoff, that is a bit porky. Still, you have plenty of wing area so it will probably be fine. The flair pup is more or less a scale 1 1/2 strutter with broader wings of shorter span, no rear cockpit, and a set of struts missing! Adding a more scale length undercarriage to the flair model makes it look much better by the way. The flair se5a is a model i am on the lookout for. I have the Nieuport (see below, saito 45 and about 6.5lbs?) flying but also have a baronette to build. Im quite looking forward to that ?

 

 

Gary, replied to your earlier post while you were writing ? yea i see what you are saying, but if we have as an example a 62 inch spitfire that will fly at 9-10lbs. It only needs an 80, so an 80 with ballast will be fine. Fitting a 100 and not using the ballast will work, but you have a wasted engine and assuming you fly the model the same speed, you use more fuel, the engine is more expensive, you need a bigger tank and so on

Edited March 12, 2021 by Jon - Laser Engines

[Gary Manuel]

Good question in your final paragraph Jon, and one I don't know the answer to, so I'll throw it open.

 

Which engine uses the greater amount of fuel; a larger one running comfortably or a smaller one at the limits of it's capabilities?

 

Bare in mind that both are doing exactly the same amount of work. My suspicion is that the larger one will use the least fuel because it is working well within it's design envelope and therefore at a better efficiency.

 

Do you have efficiency curves for the engines you produce?

[Jon H]

We are well down the rabbit hole now!

 

But sure, a small engine flat out is likely to be les efficient than a bigger one just doing its thing. Years ago i had a rover 200 car with a 1 litre engine. Fuel consumption was higher than the 1.4litre version of the same car as you always had to give it the boot to get the blasted thing to move. The same is true for models. 

 

In my example above though, an 80 would pull a 10lb Spitfire at say 60-70% throttle for scale speed in level flight. The 100,maybe 45-55%? As you say though, both engines are outputting the same power (thrust) to give the same speed, but the 80 is likely doing it at higher rpm. The capacity of the 80 is smaller though so its using more smaller fuel charges than the 100 which is using fewer, but larger charges. Factor in that glow engines are quite inefficient below about 50% throttle due to the way the carbs work it could be that the 100 uses a fair bit more fuel. All that said, in this example the engines are close enough in capacity that its likely a wash. If we take my earlier example of needing a 70 or 80 but using a 120, the 120 will use more fuel irrespective of its rpm just because its so much bigger and its power output on the same fuel consumption at the 80 running normally may infact be less as it could be at only 1/4 throttle and low rpm. On the flip side, if the model was under engined with say a 60 4 stroke, and propped for maximum revs/power (hp) from the engine as itts really too small for the job, the 60 is likely to use more fuel than the cruising 80.....although, a engine running fast on a light load will use less fuel than an engine running slow on a heavy load. 

 

To say its complicated would be an understatement, and certainly investing specific fuel consumption of model engines is not something that is really worth doing. For airbus building an airliner, sure its worth the cost of investigating it, for boys and their toys...not so much. 

 

In general though, i would always aim for a powerplant that runs at 50-70% power most of the time when used with a sensible prop (not 8 foot long and not a tooth pick either). This keeps the engine hot (good for the oil, reliability, keeping the crankcase free of contaminant's to prevent rust), keeps it in its most efficient throttle range, its not overloading it...etc, and it tends to just be a happy place for most engines. 

 

As a side note to all this, and probably a topic for another thread, most models these days are well over powered. I suspect this is due to the easy access to higher output power plants and their relatively low cost vs historical options. A guy my dad used to fly with had a kit built acrowot and it flew on an OS48 surpass. It flew from land, water, snow, was fully aerobatic and did all you could ever ask of it. I used to fly one on a 40la and it was fine. Now, most would scoff at anything smaller than a 70 4 stroke in the same model. 

 

The flair pup/fokker DVII is another example. Again, the OS48 surpass (later 52) flew my dads pup and an ASP52 flew my DVIII with ease, and yet i get customers asking me for 80's for the same model. Why? I have flown a flair pup with a laser 70 in it and it was awful. Two clicks over idle and the thing was off like a rocket. The same was true of a 72 inch piper cub. As i have mentioned before, my flying test bench is 86'' span and somewhere around 20lbs. It is aerobatic and very enjoyable to fly on a 120 4 stroke. You cant just bank and yank it, and need to plan things a little, but it is fully capable on a 120 if you fly it right. 

 

To bring this full circle, i think the perception of how much power is needed is as much to do with an aggressive flying style and poor propeller choice than anything else. The wrong prop and loads of airframe drag caused by banking and yanking instead of smooth flying This lead vs bigger engine thing comes in here as everyone thinks they need more power than they do because of this perception. Loads of power will also hide deficiencies in flying skills, circuit planning and sequencing of manoeuvers as you can just power though the lot and not worry about maintaining the momentum. Its also more dangerous for the model. Higher loads, more speed, less time to fix things if you make a mistake, and the power to flip your spitfire over if you just firewall the throttle from low speed due to excessive torque. 

 

 

I hope all that made sense. We are a bit off the OP now so apologies for pulling the thread a bit. The whole thing of weight and power is rather intertwined! 

 

 

Edited March 12, 2021 by Jon - Laser Engines

[john stones 1 - Moderator]

Whole bundle of questions and chat to be had there Gary/Jon, could be an interesting thread of it's own.

[Gary Manuel]

Jon,

Yes I agree that it's a complicated subject and I'm certainly no expert. Funny you should compare cars with models because I feel exactly the same thing. Cars with small engines take so much more management and forward planning on the road, especially approaching hills, bends and other obstructions. I must admit that it's a lot of fun using your skill and judgement to outsmart the Audi / Merc / BMW driver as you time your approach to the traffic lights in your Fiat Panda and leave him standing as the lights change. I think models can be similar. It is a lot of fun taking off and flying round at just above stalling speed (or below, if you have a big enough engine).

 

I'm also with you in thinking that an engine is probably most efficient at 50-70% power, rather than 90-100% which is what I had in mind when suggesting a larger engine to keep it in this region.

 

It regularly frustrates (and amuses) me when I see members repeatedly attempt to take a scale war-bird off. They give it full chat and after 100 yards, barely get enough speed up to get it off the ground and then see it roll to the left before crashing to the ground. All due to insufficient power and air speed, resulting in a stall as the angle of attack increases after take off. This breaks down the air flow over the wing resulting in a reduction in lift. It's so obvious what's happening when you understand the underlying principles. The models in question are obviously underpowered but have their cowls stuffed with lead in order to make them balance. These are the models that would benefit from less lead and a bigger engine. To me, it's a no-brainer.  

 

I agree with you that modern thinking supports using larger engines rather than the barely adequate ones from bygone days. I also agree that power can become a substitute for skill, but as I said earlier, the throttle is infinitely variable (I don't use throttle ratchets, I prefer a smooth but tight throttle stick), so you can use as little or as much as you need. If you want to fly the difficult way, on the verge of a stall that's OK, but it's handy having the option of powering yourself out of trouble.

 

Here's a final thought. If you could go back in time and ask WW2 Spitfire pilots whether they would prefer lead or a bigger engine up front, what do you think their answer would be?

 

It's been nice having this slightly off topic discussion, although it was a natural drift from the question of how heavy your plan built models are. I think the mods and readers may forgive us.

[Chris Walby]

Hi,

 

All good stuff and well off topic, but no problem for this thread. ?

 

I am not sure I agree with Gary and I think the point Jon is making is relevant. As a well know tire manufacturer used to say "power is nothing without control" and I am not talking about a marginal overpower set up. If a model will fly nicely on a 70 size why put a 100 or 120 in it? It will just make it harder to fly and stress the airframe unnecessarily. I not talking about a nip it up a bit here, but well over powered.

 

Couple of examples

I have a ARTF Acrowot with a Laser 70 in it (it is very slightly under published AUW), ok it won't do unlimited verticals, but it does everything I want and one of the club instructors rang it out and declared it was really nice. My point is I have never ripped the UC plate out of the fuz (like many) and you just have to watch a bigger engine version come in markedly faster with  what appears to be a more abrupt stall.

 

My Yak has a 180 in it and again won't do unlimited vertical, but I find it really rewarding to fly by using the mass of the model and yes it could be pushed harder with WOT but it does not reward me any more.

 

Good point about firewalling on take off and again I have been advised by pilots far more experienced that snapping the throttle wide open just leads to more problems due to swing and possible engine quitting at the most critical point of the flight.

 

Rather out to lunch of the subject of electric and counter rotating props, yes it reduces the swing, but as mentioned above with a good dollop of rudder is it really an issue or a case of hiding poor control.

 

And don't get me on the subject of totally un-scale flying of warbirds....

 

PS I think we have answered the OP question...its definite maybe.

[David Davis]

My first successful r/c model was a Flair Junior 60, which I built in 1988. I'd built several free flight and control line models by then so the construction of the model wasn't a problem. However, I'd failed to reserve the lightest stripwood for the tailplane and in fact I built the tailplane out of the heaviest wood in the kit. With the fuselage covered in doped nylon and an Irvine 20 in the nose I still had to add one and a half pounds, yes, one and a half POUNDS or 0.68 kgs of lead to the nose. The model was considerably over-weight but it flew well in a wind! I learned to fly on it. Later on I built a lighter tail and was able to remove all of the lead from the nose.

 

Last year I built another vintage model, a Big Guff, perhaps the first model aircraft to be designed specifically for radio controlled flight. The original model weighed 8lbs (3.6Kgs) but 2lbs of that was the weight of the receiver and its HT dry-cell battery. Modern equipment is of course much more compact and lighter but my Big Guff weighed 8lbs 8ozs. 1lb 8ozs of that was the weight of the 6" Du Bro wheels which my partner bought me as a birthday present. It still flew well! 

 

The model's fuselage and tailplane were destroyed in a fire. I'm building a second fuselage. I wonder what the new model will weigh! 

[Bob Cotsford]

Too much or just enough power?  Depends on the model.  A vintage model will be a handful with too much power while a classic aerobatic model is more of a ballistic missile and it's hard to overpower something like a Curare or even a sports model of that era such as a Bullet or Tornado.

Talking of Acrowots, my old kit built one flew a treat with an ASP 52 4 stroke - as a small field aerobat.  With a 61 2 stroke it was a different beast, ideal for big sky aerobatics.  Horses for courses. 

[Martin Harris - Moderator]

Perhaps lighter is better doesn’t always apply?

 

I’m (slowly) building a Tempest from plans. It is an old design from when scale competition designs had to comply with a 5kg maximum mass requirement. 
 

Some years later, the designer built another that came out at around 7kg and he reported that it was a much nicer model to fly in a scale manner.  He also test flew one with a Quadra petrol engine which was approaching twice the mass of his original and flew well too!

[Jon H]

As everyone seems ok with the digression perhaps we should run with it

 

Gary, your point about a model (of any kind) wheezing along unti8l the curvature of the earth helps it get airborne is fair enough. My Airsail Piper Tomahawk (72 inch, about 7 lbs i think, enya 53 4 stroke) falls into this category but mostly because its wheels are really draggy. They spin freely, but they are so close together it is not very stable and spends as much time wobbling about as it does accelerating. Once off the ground though the enya 53 is back to no more than half throttle and the model is very slippery. 

 

The reason i bring this up is because the choice of engine in the examples you give might not actually be the problem. It could be the wheels, the wrong prop, the constant obsession with running the engine rich robbing power, pulling the model off too soon so its nose it stuck in the air and it cant accelerate. 

 

I would also ask, how many of those warbird stall/spin takeoff accidents came as the pilot had lost directional control and was trying to haul it off to avoid something. I see so many guys firewall their throttle and do a gentle left turn to end up 90 degrees off runway heading. Realising all is not well, they haul on the elevator with predictable results. 

 

In my experience at work, its not often that i agree with a customer when it comes to engine choice. Most of the time i recommend something smaller than they think the need, but it can go the other way. A chap wanted to order a 150 for a 1/4 flair stearman a while back as its on the plan. He was shocked when i said the 300 was our normal choice for that model. Its the same for Brian Taylor models. The 70inch 109, P51, Spit and Hurricane are hopeless with an 80 fitted so use the 120. BT got away with it as he built it from thin air and flew it twice off a hard runway, wont the trophy, and went on to the next project. 1/4 tiger moths are also better with the 180 vs the 150 due to the bigger prop you can use. 

 

 

There is one issue we have not covered much and that is choice. Some people want all of their models to fly the same. Extra 300, tiger moth, spitfire. Whatever, they all need to do 500mph and be thrashed until their wings snap. I had a bit of a debate in the comments section of a youtube video on this topic where an overpowered (laser 155 fitted, i recommend a 100) seagull chipmunk was being thrashed as it were an extra. The counter to my comment that a 100 was more  appropriate was that it would make the model boring, so boring in fact it would go on ebay. I was also lambasted for being a 'purist' which in fairness i took as a compliment. Anyway my answer to this was...you bought the wrong model. Its a chipmunk, it does chipmunk things and that is why you bought it. If you want to fly like an extra, buy an extra! The problem is, someone with this mentality that everything needs infinite power will mislead those who dont want that sort of performance. Its why i always ask customers what they want. DO they want scale performance, or toy aeroplane performance? Very often the lower performance/cheaper option is welcomed and in 10 years i have not had anyone call me and complain their model is not powerful enough. 

 

Forums are a problem (not this one clearly) as advise from American flyers is often best ignored (sorry if any american's are watching) as they love their speed and power. 60 inch warbird...200 4 stroke and 30% nitro. Flying weight? 16lbs!! They think its awesome, i wonder how its undercarriage dont fold up just putting it on the ground. 

 

One final thing, engine recommendations on plans. I had a conversation with a customer in the week. 58 inch tiger moth, plan says 60 2 stroke so was asking about an 80, i recommended a 50 4 stroke and said none of our engines were suitable as the model was too small even for the 70. Why is a 60 on the plan then? Age. It was a very old plan, and i suspect the merco 61 was the intended power plant. The merco 61 being well known for not having as much power as a modern 36. Modern engines are simply more powerful per cc than engines of the past. Plans and kits of the past also had to make do with whatever was available. If they needed a 90 but none were available, a 60 wont do so its 120 time. 

 

[John Stainforth]

Jon, you are right about American pilots liking their power! In the club I belonged to in Houston, they would invariably put in bigger engines rather than add nose weight. One of the best pilots there (actually, probably the best model pilot I have ever seen - his landings were 10/10 absolutely every single time) was a full size pilot flying 737's for United. I think he liked to do everything with his models that he was not allowed to do in airliners. His buzz was taking  standard 60-size trainers, beefing them right up, and putting in multiple engines. The first of these had two OS 90's; that flew really well and like a bomb. Then he built another with four OS 55AX's. He gave that a broader tailplane (sorry, horizontal stabilizer) with two outboard fins (vertical stabilizers). That flew and looked a bit like a Mach 2 Lancaster. It's rate of climb was phenomenal - and those four engines made a beautiful sound.

[Martin Harris - Moderator]

2 hours ago, Jon - Laser Engines said:

I had a bit of a debate in the comments section of a youtube video on this topic where an overpowered (laser 155 fitted, i recommend a 100) seagull chipmunk was being thrashed as it were an extra. The counter to my comment that a 100 was more  appropriate was that it would make the model boring, so boring in fact it would go on ebay. I was also lambasted for being a 'purist' which in fairness i took as a compliment. Anyway my answer to this was...you bought the wrong model. Its a chipmunk, it does chipmunk things and that is why you bought it. If you want to fly like an extra, buy an extra!

 

Oh how much do I agree with this!

 

I assume this was the 1/5 scale version?  I have an Airsail 1/6 scale (69") Chippie which I built in 2003 as my first build after returning to the hobby and my first experience with 4 stroke glows.  I was planning to fit an OS 52FS and everyone at the club told me that it would be far too small and I "needed" a 70 at least.  I dropped an email to the designer, Brian Borland and he replied saying that the prototype flew really well on a "worn out" 40 FS.  I went ahead with the 52 and I have to limit throttle opening to about half in order to get anything resembling a ground run.  In reality, it has far better climb performance than the full size and more than adequate power for scale aerobatics.

 

How many times have I seen people recommending a 70, 80 or even 90 for similar sized Chipmunk models? I'd put money on the ARTFs being lighter than my solidly built and "Action Man/Barbie crewed" example which weighs 8 1/2 pounds dry - and to steer this thread gently back towards it's intended track, this is against the box lid weight for the kit being under 6 1/2 !

[Gary Manuel]

Hi Jon.

Once again I find myself agreeing with most of your comments. I recognise your description of the narrow tracked wobbly wheeled war-bird, zig-zagging it's way down the runway. Its touch and go whether the model actually gets off the ground but if it does, it's anyone's guess which way it will be pointing and which wing will be lower than the other when it does. The biggest mistake they made here was not chopping the throttle at the first sign of trouble and having another go.

No, this is not the scenario I'm describing. This is clearly not down to lack of power, it's down to the model's ground handling characteristics or possibly poor throttle control inducing the start of a ground loop which they over compensate for. What I'm talking about is where the model chugs down the runway but just can't reach take off speed. Maybe the friction of the long grass is a factor, but not the route cause.

In either case, the model does fly OK if it does become airborne. The problem is that it all needs to be repeated again for the next and every subsequent take off. A bigger engine or a lower all up weight is the real solution.

 

A few posters since yesterday have commented that a model with an oversized engine can fly like a pig and can be difficult to land because the landing speed is higher with the bigger engine. I agree.

 

Let me clarify that I am not advocating the use of oversized engines just for the sake of it (I'm not American). I strongly believe that an aeroplane should be as light as possible. Simply whacking a big engine into a model does the exact opposite. What I'm saying is that (only) IF weight is needed up front, then using a larger engine rather than lead will usually result in a model with a lower all up weight and will certainly result in a model with more useful power which you may choose to use or not. 

 

Back to Jon. I agree with you about the engine size recommended on (older) plans. Engines have got lighter and more powerful than they used to be for a given size. Maybe that's why we find ourselves needing to add lead that perhaps wasn't needed with the older, heavier engines?

 

So what's the best solution to this? Build lighter, definitely. Use a bigger engine, maybe. Add lead, If you must. There's more than one way of doing things and there's no right / wrong way, but I have my preferences based on logic and sound principles.

[Jon H]

The airsail Chippy is a no brainer for a 50 4 stroke (13x5 prop) and this seagull version, 80'' and 10-11lbs, seems ideal for a 100 to me with maybe a 16x6. A customer has an 82 inch 15lb plan built example with a laser 155 fitted (17x8) and it will loop from level flight at 1/3 throttle. I have flown in a full size chippy, and we had to inform it in writing when it was time to do a loop. 

 

This is also borne out by the old black horse 45cc chipmunk (85 inch, 14lbs i think) being flown on an OS120 pumper! 45cc would tear it a new one. 

 

[Jon H]

Gary we are playing posting tennis. 

 

I think the overall outcome from this is as follows:

 

Build as light as possible, especially at the back end, but dont bust a gut. Just use common sense especially when it comes to paint/glass cloth etc. 

 

Stuff the equipment as far forward as possible. 

 

Choose an engine that actually suits the likely AUW (not what people think suits it), then ballast as needed. 

 

If your model ends up a little heavier than expected, and you have a suitable slightly bigger/heavier powerplant, wedge that in instead. 

 

To use some of the examples from the chat, a 60-65 inch warbird of 8-10lbs is looking for 70-100 depending on what it is. P47 is draggy, use the 100, P51 is sleek, use an 80 etc. 60 inch Tiger moth/stampe/pup etc. 8lbs? maybe up to 10? 50 4 stroke, 60 at the outside and propped large/fine. These light/slow aircraft are designed to fly with their wings not their propellers, so try and do the same ? 

Edited March 13, 2021 by Jon - Laser Engines

[Gary Manuel]

?

[john stones 1 - Moderator]

2 Cermark pitts one has 91fx in fly's great, other has 30cc petrol in, it's a brick, first one has ample for big aeros, lands nicely even deadstick, joy to fly, tother ? well it's quick but does little, always having to turn to keep within allotted airspace, goes up like a rocket, lands like one, why's it land quick ? It's way nose heavy, runs outta elevator flaring out. Speciality stunt from pilot ? flat out n too close.

 

Myself I only see a few flyers like this, I see way more underpowered models flown by petrified pilots praying it gets off without stalling.

 

Overpowered models ? Nah, poor pilots, if a 17cc petrol is a shade bigger than recommended, BUT means I don't use lead, 17cc for me, WHY, well it'll run well within it's limits, be more economical on fuel and be quieter, any of those bad things ?

P.S don't forget the throttle servo.

[Robin Etherton]

Learnt early on that light models invariably fly better than heavy ones. 
careful selection (and I mean careful) of the right grain and lightest weight I believe to be crucial to achieving lightness. Back in the days building f2b models I would not use any balsa weighing more than 8lb/sq ft and would aim for below 6. It may mean going through 40 or more sheets to find one but worth it. Forget the name of the supplier but the one that burnt down in the USA was a good source for light wood and we still have the balsa cabin in the Uk. Also always used balsa cement and pva(not epoxy) for the stressed points. 
Just my point of view of course.

Also used 10 micron Mylar with a top covering of lightweight tissue to keep the weight down. Virtually puncture proof and oh so light.

[Matt Carlton]

I'm not sure that a bigger engine is always a better option than a bit of lead. Take that too far and the structure would need modification to handle the extra weight, vibration, tank size etc. Which could in itself add more weight ad infinitum. 

 

I'd rather wedge a bit of lead in the nose of a vintage model than try to shoehorn a bigger engine in. 

 

There's a tendancy to use the available oomph. Resulting in that rather popular phenomenon in the USA, namely every scale model of whatever kind weighing twice what it needs and flying at a scale 650mph. Personally I just shudder at the sight of a Sopwith Pup climbing vertically and rolling 720 degrees per second. All with a "mega power 75cc engine with an ultrapipe" that requires the cowling to be cut back more than public services in a recession. 

 

 

 

 

[john stones 1 - Moderator]

Like the cut back comment. ?

 

[Geoff S]

59 minutes ago, Matt Carlton said:

I'm not sure that a bigger engine is always a better option than a bit of lead. Take that too far and the structure would need modification to handle the extra weight, vibration, tank size etc. Which could in itself add more weight ad infinitum. 

 

I'd rather wedge a bit of lead in the nose of a vintage model than try to shoehorn a bigger engine in. 

 

There's a tendancy to use the available oomph. Resulting in that rather popular phenomenon in the USA, namely every scale model of whatever kind weighing twice what it needs and flying at a scale 650mph. Personally I just shudder at the sight of a Sopwith Pup climbing vertically and rolling 720 degrees per second. All with a "mega power 75cc engine with an ultrapipe" that requires the cowling to be cut back more than public services in a recession. 

 

 

 

 

 

I agree but I did once see Ian Redshaw prop hang either a quarter (or perhaps third) scale Sopwith Pup or Camel after he'd done some repairs/overhaul for someone.  He does, however usually fly WW1 aircraft in a very scale like manner to the point of blipping the throttle on landing approaches to simulate switching the magneto on and off as per the full-size so he's forgiven.

 

Most (all?) models fly far too fast for scale, mostly because they aren't flying in scale air or scale gravity.  Some years ago I was privileged to witness Andy Sephton performing aerobatics over the RR Hucknall airfield in the company's Spitfire one Friday afternoon.  The aircraft was flying so slowly (apparently) I thought it would fall out of the sky.  I was just too used to watching models flying aerobatics, I suppose.

 

Geoff

[Eric Robson]

I built a Gordon Whitehead Tiger Moth the plan called for a 20two stroke,  I put an OS 25FSR in, it  flew like a Pitts Special. I changed it to an OS 20 max and it flew like a Tiger Moth, much better than tearing round the sky like a scalded kitten.