French Radio Queens

[David Davis]

I retired to the middle of France in 2015 and joined the local model aeroplane club. About eighteen months ago I was approached by a Belgian chap, Frans, who asked me to recommend a model which he could build and which would be easy to fly as he was a novice pilot. I recommended the Radio Queen. Unfortunately the Ben Buckle Radio Queen kit was not available at the time but through these columns I managed to buy a kit from another British aeromodeller who also lives in France.

 

Another of my clubmates, Francois Dutreuil expressed an interest in building a Radio Queen because our 46 powered ARTF trainers are too fast for elderly beginners at least for the first few flights, so the plans were photocopied. Francois finished his model and ten days ago brought it to the field for its maiden flight. Francois is our oldest member at eighty-two years old. He's a competent pilot and an excellent builder who has always used Futaba equipment. Being a retired ship's engineer he has a technical background and these days he only builds and flys electric powered models. All of his models have one battery for the motor and another for the receiver. He does not trust the BEC! He had a look at the 4-Max website, noted Max's recommendations for the Radio Queen and bought the equivalent motor, ESC, propeller and LiPo for the model from a French supplier.

 

As the Radio Queen is a British design and the first model aeroplane to cross the English Channel, I thought I'd better help him out. After a lot of adjusting things on the transmitter, Francois plugged in his motor battery and advanced the throttle to find that the motor was running backwards. While I swapped over two cables, Francois made more adjustments on his transmitter. We connected the motor battery and this time we found out that the throttle controls were reversed! Then he hit the throttle-cut and a very powerful electric motor immediately went to maximum speed! Fortunately I was holding on to the model at the time and on hearing the noise, two clubmates came to our aid and with them holding the model I was able to disconnect the battery.

 

Once everything was put right Francois took off, found that the model was massively overpowered, flew one circuit and landed. It glided well. He plans to try it with a 3S LiPo.

 

Frans's model is near completion. He has not bought the motor, speed controller or battery for it yet but I have a Protronik DM 3820 motor and a 95 amp speed controller currently not doing anything. We intend to install them into his Radio Queen to see whether it will fly on 3 cells.

 

My take on this is as follows. The Radio Queen which crossed the English Channel was powered by an ED 3.5cc diesel engine and was carrying quite a fuel load and much heavier equpment than we currently use. Consequently, the Radio Queen does not need much power to fly. The DM 3820 can power a model weighing 6kgs which is likely to be twice the weight of a Radio Queen. 400-450 watts should be more than adequate so we'll experiment with props to acheive this figure.

 

Comments from more knowledgeable electric flight enthusiasts will be welcomed.

 

Some pictures of last week's events for your amusement. Sorry about my dog photo bombing the second picture. More to follow.

 

Happy Landings

[GrumpyGnome]

I'm not having a go at 4-max, but all the planes I have seen using the recommended setup have been overpowered...... all vintage/old time/trainers

[J D 8]

  We do tend to overpower vintage/trainer types these days. Not to much a problem if throttle works.

  Last year I fitted an old Ezee Pzee trainer with an Irvine 61.  Throttle link failed and motor went flat out, going like the clappers elevator flutter result below.

[David Davis]

Quite so. My Radio Queen was powered initially by an OS52 FS. It flew mostly just above tickover. I replaced it with an OS 48  FS Surpass. It didn't make a lot of difference. I've seen them fly quite adequately on a 40 four-stroke.

 

Picture of mine below with a Flair Hooligan. I wish I'd never sold either of them!

 

 

[Andy Gates]

Personally I think we modellers over power absolutely everything we have.

 

If we took a little more care in our building and power profiles, I am sure all of our machines will be much nicer to fly.

Old timer aircraft were designed in a time of limited power & heavy radio gear so they really do not need much power.

Same applies to the early electric planes, heavy motor / batteries - limited power so light air frames.

 

I love flying my light planes, most of which are balsa plan builds around 80" wingspan, around 4lbs in weight and fly beautifully on 3S lipos. If they crash, they carry so little weigh that normally the damage is quite minor.

 

95 amps on 3S is about 1000 watts. How heavy is your plane??

The specs I am seeing are 82" wingspan and a weight of 3-4lbs.

That would equate to around 400 watts needed in my book, on 3S that is about 30 amps. I would be aiming at a motor around 800 - 900kv on a 12" x 6" prop, even then I suspect you will be flying around 1/2 throttle.

[David Davis]

Frans's model is not quite finished. I thought I read somewhere that a Radio Queen weighed 6lbs. The motor has a kv rating of 660. Is 50 watts per lb adequate for a Radio Queen?

[Paul De Tourtoulon]

4 minutes ago, David Davis said:

Frans's model is not quite finished. I thought I read somewhere that a Radio Queen weighed 6lbs. The motor has a kv rating of 660. Is 50 watts per lb adequate for a Radio Queen?

Haven't you got this in your 'favorites' ?.

 

https://jivaro-models.org/formules_magiques/page_formules_magiques.html

[David Davis]

1 minute ago, Paul De Tourtoulon said:

Haven't you got this in your 'favorites' ?.

 

https://jivaro-models.org/formules_magiques/page_formules_magiques.html

No I haven't Paul but thanks for the link. I only have two electric powered models. If it were my Radio Queen, I'd put a four-stroke into it and have done!

[Andy Gates]

26 minutes ago, David Davis said:

Frans's model is not quite finished. I thought I read somewhere that a Radio Queen weighed 6lbs. The motor has a kv rating of 660. Is 50 watts per lb adequate for a Radio Queen?

What prop is fitted David, could you go up a size or 2?

50 w/lb may be a bit marginal, 75 w/lb would be better

[David Davis]

At the moment Andy the motor is not fitted to the airframe, the fuselage is not covered and Frans is in Belgium for a couple of weeks! We'll experiment with props when he returns and the model is ready.

 

Francois, who built the over-powered red and yellow Radio Queen, hopes that a 3S battery will be sufficient to fly his Radio Queen.

 

We are not allowed to fly until 9th March anyway. The French armed forces are staging a large exercise involving a lot of extremely low level flying. Not that I've seen any evidence of it so far! 😃.

[Andy Gates]

David,

 

Here is a link to my Ivan Pettigrew machines all of which are around the 80" mark and all run on 3S (Chipmunk can run on 4S but unnecessary). Just to show it can be done.

 

Regards,

Andy

[David Davis 2]

We've not done a lot to the Radio Queen recently because Frans has been away in Belgium but yesterday we covered the fuselage. We connected a 3s LiPo to the ESC and motor and fitted a 15x8 propeller. We also connected up my new watt meter and found out that at full throttle this set up was drawing 300 watts so if the Radio Queen weighs six pounds that 50 watts per lb. Currently I have no means of weighing the model because my digital kitchen scales no longer work. I wish I still had my mother's cream and red plastic set with a spring and a circular display in pounds! Perhaps a bigger propeller will be necessary. Calm weather is forecast tomorrow. We hope to give it its maiden flight then.

 

I should explain that the LiPo, speed controller, motor and propeller all belong to me. They were just sculling about unemployed in my workshop. Potentially this combination could power a much larger and heavier model than the Radio Queen but it was what we had available at the time.

[Paul De Tourtoulon]

You could always use the old see-saw method for weighing it, a wooden spoon handle as a fulcrum a plank of wood and a kilo or two of sugar,,,

[Don Fry]

Reckon it will work, but a 16 or 17 x6  would do better thrust for such a slow aircraft.

[David Davis 2]

I suspect I've got an i/c prop that size. I'm not that interested in electric flight.

[David Davis]

Maiden flight of Frans's Radio Queen this afternoon. It was massively overpowered by its Pro Tronik DM2830 turning a 15 x 8 prop and it required some lead in the nose but once I'd calmed things down a bit it flew quite nicely and I flew for seven minutes before effecting a good landing on the glider strip. At least we know that it will fly on a 3S LiPo.

 

Options are to keep the power train and fit a much smaller prop or to by a less powerful motor and ESC.

[Don Fry]

15x6 prop? Give you nice flight times.

[David Davis 2]

We were using a 4400mAh 3S battery to provide some weight up front. The LiPo, speed controller, motor and prop all belong to me and are just out on loan. I am going to recommend that Frans buys a smaller combination which would still have the ability to fly the model. We have not weighed it yet but according to the 4-Max site, a Radio Queen should weigh 6.5lbs or just under 3 kgs.

 

I am going to suggest that Frans buys a Pro-Tronic DM 2625-900 motor with a 45 amp speed controller. This combinationapparently produces enough power to fly a 3kg trainer so should be ok in the Radio Queen. The existing equipment provides far more power than is either necessary or desirable.

[David Davis 2]

I've just had an email from Frans. He and his wife have weighed the Radio Queen on their kitchen scales at 1857grammes which is just over 4 lbs. I'm not sure whether that includes the 4400 3S LiPo or not but even if we add the weight of the LiPo, 300 grammes, that takes the weight of the model to 2157 grammes or about 4.75lbs. A power train producing 250-300 watts should fly the model well. The current system has the potential to produce 700 watts! No wonder the model was a bit lively yesterday!

 

Quite how 4-Max reckons the Radio Queen weighs 6.5 lbs, I can't imagine.

[Don Fry]

Don’t quite see your logic. Unless you want your power train back, for no work the model now balances, and flies.  It just need to loose some power. The way to that is just to reduce the diameter of the prop. And flight times go up as the amps drop, and everything is non stressed.
Changing over to a higher KV motor just ups the revs, with a smaller prop still to get similar thrusts, work to achieve it, and rebalancing. 

[David Davis 2]

Quite right Don. I have no plans to use the motor or the ESC, or indeed any plans to build an electric powered model so I might as well sell them to Frans for a consideration and fit a smaller prop as you suggest. The model still needs a little weight in the nose and I'd like my 4400 LiPo back to power my starter motor!

[Don Fry]

So he needs a 6000 3s pack. That is a pack for a days flying. Tell him he also needs a deckchair, and a corkscrew in his box. 

[David Davis]

We flew it again this morning. We used my 4400 mAh pack and added a little lead and some downthrust on the motor. With a 12 inch prop it flew very sedately. Frans plans to buy a 5000 mAh LiPo for it.

[David Davis 2]

At last some good news to report on Frans' Radio Queen.

Having replaced the Pro-Tronik 2830/660 with an AXI 2820/10, because I thought that the model was over-powered and that was all that I had sculling about, having fitted a 12 x 6 prop and a huge 3S LiPo, we then tested the model's centre of gravity which turned out to be nose heavy. Nevertheless I flew it last Wednesday.

The Axi provided plenty of power but not so much as to make the flight unpleasant. However, I found that the rudder was not very effective and the model frequently floundered about the sky with me using full rudder to get it to turn. Now the rudder on the Radio Queen is pretty small but my old i/c powered Radio Queen, pictured below with my much younger self, did not display this characteristic.

Having landed the model we fitted a 2200 3S LiPo in order to bring the balance point further to the rear. This resulted in improved performance but I was not happy with the model's turning characteristics nor with the plastic clevises on the rudder's closed loop.

Yesterday morning we retired to my workshop where we were able to fit metal clevises. We weighed the model and tested the motor's power. We tried a variety of props and most of them produced just over 400 watts. On my old fashioned kitchen scales the model weighed about 5lbs or 2.2kgs so we were getting 80 watts per lb or 177 watts per kg if my arithmetic is correct.

There remained the problem of the rudder response. The cables were on the furthest hole of the servo output arm and on the second hole of the rudder horns so not much scope for adjustment there. Thoughts of building a bigger rudder were dispelled when I realised that it was 2023 and not 1973! I could adjust the rudder throw by increasing the travel of the servo on the transmitter, a Spektrum DX9.

Having adjusted the travel from 100% to 150% we retired to the flying field. The model was transformed! It took off fairly quickly and climbed well but throttling back produced a model which cruised about the sky and was very pleasant to fly. Just like my old i/c powered version.

After five minutes I bought it into land out of respect for the small LiPo. We will try a 3300 LiPo placed further back in order to get longer flight times.

 

 

[David Davis]

As I have posted elsewhere we finally got Frans' Radio Queen to fly well on a much less powerful motor which produced 320 watts on a 10x7 prop and 3S Lipo. This produced 67 watts per kilo. We had previously been using much more powerful motors. The new motor is tiny compared to the previous ones and before it actually took off, I wondered whether it was going to be a car!

 

Having studied the plan I noticed that the engine bearers were spaced for a 2.5cc engine.

 

Now that would be a challenge!