VQ Beechcroft Baron 3 blade prop

[toto]

What would be a suitable 2 or 3 blade prop size for the VQ beechcroft Bsron if teamed up with 2 x Force .48 2 stroke glow engines. 

 

Any recommendations ?

 

Toto

[J D 8]

Could that be a Beechcraft Barron? You have one ?

[toto]

I have one ..... 

[Eric Robson]

I would not advise fitting 2 x46 ic engines in a 60" aeroplane especially as you are new to the hobby. It would fly at a totally unscale speed. Twin electric would be the better option as they are more reliable. An engine cut is usually the end of the model. 

I prefer ic but all my  multi engine models are electric. 

[toto]

No worries.

 

I think the electric equivalent specified was a couple of boost 50's. Again, maybe an over powered spec. 

 

Toto

[J D 8]

The recommended engines are 35's

[toto]

Hi J D 8,

 

I had read the same but some have stated between a 35 and a 46. 

 

The 46 option would also maybe lend itself to having more potential for swapping out into other models. 

 

However that's the beauty of being able to throw the question out there in order to get the right answers / choices. 

 

Eric's comments on engine cut is a sobering thought so maybe electric after all. It's a difficult thing to guard against though as the same can be said for single engine IC models, not just twins. 

 

Toto

[PeterF]

38 minutes ago, toto said:

 

Eric's comments on engine cut is a sobering thought so maybe electric after all. It's a difficult thing to guard against though as the same can be said for single engine IC models, not just twins. 

 

Toto

Toto,

 

Your response shows your lack of experience here. There is a lot of difference between one engine stopping on a twin and the engine stopping on a single. On a twin if one engine stops the thrust on one side of the plane can pitch the model into a spin. You may be quick enough to catch it by pulling the other engine back in power or putting in a lot of rudder.

 

I have flown some larger twins in both IC and electric and managed to bring my 80" DC-3 down on a single IC engine once, an experience I never looked to experience again. You often end up flying them on IC very conservatively always but clenched waiting for an engine out. Before you do an IC twin you need to be able to operate your engines to the highest reliability.

 

All my twins are now electric and I am much calmer when I fly them and now enjoy the experience of flying them. I have a large Mosquito, when it was IC I just flew circuits or figures of 8 high up, minimum risk of losing an engine. Now I have converted it to electric I am happy to bring it low, do large wingovers, rolls and even a loop or two. I never risked that when IC.

[toto]

Thanks for the explanation. What happens if a single motor was to fail and your left with one ?

 

Toto

[Eric Robson]

Peter, like you my only successful single engine landing on a twin was my DC3 80" span, I've lost 3 twins on engine cuts, the worst was a Brian Taylor Me 110 which spiraled onto a concrete runway, it was very fast with 2 OS 25 fsr motors 71" span. I have 5 electric twins and fly them without any worries. Our club instructor was flying a DC3 one day last year, I said very good but its flying like a pylon racer he dropped the  speed  and on a turn one engine cut, it is now repaired. 

[PeterF]

As I said above

 "On a twin if one engine stops the thrust on one side of the plane can pitch the model into a spin. "

 Depending on the model

1. you may need to bring the remaining engine back to idle and dead stick it in, you

Or

2. You may be able to continue flying with rudder compensating for the unequal thrust, but you need to know which engine has stopped.

 

Once on one engine things are on a knife edge, if you are coming in with an engine on tickover and need to power up you have to do this cautiously, fast throttling up can bring on the spin you have been avoiding. I am sure I have some articles, if so I will add them in another post.

[PeterF]

https://www.modelairplanenews.com/multi-engine-magic-expert-set-up-flight-techniques-for-twin-engine-aircraft/

 

https://www.modelairplanenews.com/tips-for-flying-twins/

 

https://www.ccrcc.com/so-you-want-fly-twins/

[Jon H]

The guys are right that twins are a very different kettle of fish to a single engine  model but the loss of an engine is not a guaranteed crash if handled correctly. The problem is, you have very little time to learn how to do it when it happens to you the first time and if you get it wrong then it will lead to a spin. This is true of full size aviation as well where light twins like the baron are very often lost due to engine failure and mishandling by the pilot. 

 

The key is speed. Most often the advice is to cut the second engine and glide, which usually prevents a spin but guarantees an off field landing and damage. I do the exact opposite and nail the remaining engine at full power and maintain as much speed as i can. This is because the aerodynamic performance of the rudder, which you need to counter the thrust asymmetry, is impacted by the speed. Below a certain speed (Vmca or velocity minimum control authority in full size parlance) the rudder no longer has the power needed to prevent the spin so you must maintain you speed and correct the yaw with the rudder. This means flying the circuit with maybe half or more rudder held in manually as you cant trim it. If you trim it, you will be out of trim the other way when you finally throttle back to land. It must be hand flown. Above all else maintain airspeed. 

 

If you do want to get into flying model twins i recommend you buy a more sacrificial twin trainer and use it specifically for learning to fly with an engine out. Set it up so you can throttle back an engine with the flick of a switch and practice it. Once you have that done get someone to sabotage the model by short filling one of the fuel tanks and not tell you which one. Fly until an engine quits and then deal with it. 

 

Part of the reason so many model twins crash is because pilots do not want to put in the time or the money into training themselves before jumping to the P38 or mosquito or whatever they have their eyes on. This is understandable as resources are finite and trainers are boring, but its well worth it in the long run. The other issue is a lack of proficient twin pilots at clubs who can teach. 

 

I have buddy boxed two club mates on one of my twins over the years to demo the challenges they faced in engine out situation. I did it as they didnt think it would be that big a deal to cope with it. Both aged a few years in those brief seconds after it quit.

 

I would strongly advise against getting into a twin at the moment toto and would give it a few years until your overall experience level has come up. The baron you have there is a lovely model, but twin 25's would fly it so your engine selection is massive overkill. A friend has one, as yet unflown, and it will use a pair of 46 4 strokes. These were used in another model of the same size and offered plenty of performance. 

 

 

[PatMc]

After a spate of crashes the RAF curtailed asymmetric training practice with Canberras because there were more accidents in these practices than there were genuine 1 engine out occurrences. 

[Jon H]

42 minutes ago, PatMc said:

After a spate of crashes the RAF curtailed asymmetric training practice with Canberras because there were more accidents in these practices than there were genuine 1 engine out occurrences. 

 

sounds like they needed a twin trainer. These days i assume they use sims. 

 

It would be interesting to see what happened to the accident rate in genuine emergencies after the training stopped. 

Edited June 7, 2023 by Jon - Laser Engines

[PatMc]

I don't know when the 1 engine out training stopped, it could be that sims were well established by then. Also if you consider the rarity of deadstick occurrences with single engine RAF jets I believe the statistics endorse the decision.

 

[toto]

There is no fear of me even thinking of flying it any time soon. I am also so much the wiser for the posts above eo let's just say that it's at the bottom of the pile for the forseeable future.

 

This is maybe something that the flight simulators could consider trying to emulate in their software. It may not quite be like the real thing but would at least go some way to helping experience.

 

It is fascinating hearing about these things though and all adds to the understanding of where these models stand in the grand scheme of things in terms of where they sit in the " easy to fly barometer "

 

Stable single engine or motor high wings, bi-planes, mid wings, low wings, gliders, jets  ...... etc etc.

 

I like the more traditional looking models ie high wing, bi planes and even the twin props etc rather than jets and even warbirds etc. Its the character that they have. I have rightly or wrongly bought a few now based purely on what I like the look of but I'm more than happy if they sit there for better ( more experienced ) times. Once actually more proficient I'll stick to some sense of proficiency led order of introducing them into the fleet. I'm happy gathering whilst I have the budget. 

 

Thanks for all the comments and although there is no immediate need from a build point of view, feel free to keep this very interesting lesson going. All good stuff.

 

Thanks in particular to Peter f for these links. I have only sped read them for now but I will be revisiting them all for sure to immerse myself again at more of a leisurely pace later.

 

Toto

Edited June 8, 2023 by toto

[Jon H]

14 hours ago, PatMc said:

I don't know when the 1 engine out training stopped, it could be that sims were well established by then. Also if you consider the rarity of deadstick occurrences with single engine RAF jets I believe the statistics endorse the decision.

 

 

Its interesting that in the airlines engine out, especially on takeoff, is a major training point. A modern airliner is likely to have a few more safeguards between pilot and controls than a canberra mind you and i do not know how many they do in the aircraft vs in the sim. 

 

AS for model sims, i have not found one that gave an especially accurate example of engine out flying. Admittedly, i only flew 2 versions of the real flight when it was on sale at the shop i worked in. We had a demo system set up and had a play every now and then.