Peterf's 1/4 scale Falcon Models Tiger Moth

[Manish Chandrayan]

Congratulations 👍.
A well deserved reward for you perseverance and dedication towards the build.
If I am allowed to criticize, the only thing missing is the sound of a four stroke engine😃.
I also think that firmer springs in the oleo's will serve better. What is your opinion about those springs?
Happy landings and I am sure you are destined for few competition wins with the fantastic model.

[Manish Chandrayan]

The rear three quarter shot with the model going away from the camera is the most evocative one. Difficult to say full scale or a model

[alan alldritt]

Great conclusion to a very interesting and informative build log.You could not tell the difference between IT and the real thing in the in-flight shots - only the bark of a Gypsy Major was missing - congratulations.

[Michael Denest]

Having put a few hours of Tiger Moth time in my logbook, I can say that the DH-82a is not an aircraft to sit in an watch the scenery go by. It requires full attention by the pilot at all times to fly the airplane and not become complacent. No wonder the RAF was able to take its pilots directly to the Spit and Hurri.

You've created an excellent model that accurately represents the Moth; enjoy it and fly safely.

I agree with Alan that all it needs is that Gypsy Major sound, but at least you don;t have to spend the time wiping down the model after each flight.

I have a suggestion regarding the aileron gap on the hingeline.  The full scale Moth has fabric gap seals doped on to the aileron leading edge and wing trailing edge.  Installing will help with better roll control and reduce the amount of adverse yaw the full size exhibits.

Edited By Michael Denest on 13/05/2018 17:07:48

[PeterF]

Posted by Michael Denest on 13/05/2018 16:40:22:
I have a suggestion regarding the aileron gap on the hingeline. The full scale Moth has fabric gap seals doped on to the aileron leading edge and wing trailing edge. Installing will help with better roll control and reduce the amount of adverse yaw the full size exhibits.

Posted by Manish Chandrayan on 13/05/2018 07:57:19:
Thanks for the comments and suggestions.I also think that firmer springs in the oleo's will serve better. What is your opinion about those springs?

Posted by alan alldritt on 13/05/2018 08:05:21:
You could not tell the difference between IT and the real thing in the in-flight shots - only the bark of a Gypsy Major was missing.

Thanks for the comments and suggestions.

The model may have a larger than scale hingeline gap on both the ailerons and the elevator and it is only seeing the in air photos from directly below that this is appreciated, I have to agree that they are very noticeable and now I have looked at some full scale photos I see that they are not visible. I will look into adding some sealing strips as I have found some full scale photos showing the seals.

At the moment I will keep the springs as supplied, the landing that was filmed was not the best one, the next flight was an absolute greaser as I learned more about landing it. The filmed landing was a bit heavy and ended in a nose over, suitably edited out. The Tiger Moth did have quite softly sprung undercarriage from what I have read.

Regarding the engine sound, after converting completely to electric powered flight, this is only the second plane where I have noticed the lack of sound as being an issue, I have a Flair Taube which used to put put around on a 4 stroke at 1/4 to 1/3 throttle and after swapping to a motor has lost something in translation. I may look into a sound module. Certainly, when flown at scale speed with a good 4 stroke at low throttle certainly adds something evocative.

[Martyn K]

Absolutely fantastic. Well done Peter..

[Manish Chandrayan]

Good that you mention about the hinge gaps Peter. I did notice it in the pictures and was wondering why did you not seal those while covering? It would be good to hear the difference in handling (if any) once you have them sealed.

Yes my observation regarding the springs was based on the landing, but then firmer springs will also lead to issues of model bouncing back in to the air in case of anything other softest touchdowns

[PeterF]

I have put sealing strips into the elevator and aileron hinge gaps, I had some of the Solartex rib tape material left over, just the right size and set up nice and slack has not impinged on the control surface movement. The plane needed a bit more trimming afterwards, but it is hard to notice that it made much difference to the handling, as noted on the initial flights, the controls were powerful beforehand. However, the largest difference is the visual aspect, no more large gaps visible in flight. We tried to take some more photos today, much better light and blue sky but my camera just will not hack it, have added a couple anyway, on this flight, the rear cockpit doors were left open inadvertently and they did not flap around.

I explored the flight envelope:-

• loops need a shallow dive beforehand otherwise it runs out of momentum at the top and skews out of the loop;
• stall turns need power kept on or it flops over backwards;
• rolls are easy due to a nice aileron response and require a healthy dose of up elevator when inverted and even then the roll was barrel shaped, but not displeasing;
• stalls were relatively benign, at 1/4 throttle it mushed around on full elevator slowly losing height but little sign of a stall, at lower throttle there was a gentle stall which was recovered after less than one rotation, however one rotation uses up a lot of height.

Edited By PeterF on 15/05/2018 21:03:57

[Richard Thornton 2]

Ah Peter, your model is looking superp, WELL DONE and all the photos both close up and in the air capture that evocative look of this wonderful byplane.

Question, where have you hidden your radio gear and switches, and are the door catches spring loaded to keep them shut. I am worried about the doors on mine vibrating open so I am trying to make them spring loaded in the shut position.

[Manish Chandrayan]

I did spy a satellite Rx beside the dummy exhaust, rest Peter needs to tell us.

Have you gone with instructions recommended throws on all surfaces or have they been changed?

[Richard Thornton 2]

Hi Manish

The throws on my model plans are missing so I am using the throws as per the full size, but not sure your question was aimed at me.

[Tim Ballinger]

Just brilliant .

Tim

[Manish Chandrayan]

Posted by Richard Thornton 2 on 16/05/2018 12:32:54:

Hi Manish

The throws on my model plans are missing so I am using the throws as per the full size, but not sure your question was aimed at me.

Hello! Richard, the question regarding throws was for Peter. The Falcon kit instructions mention the throws. What kit are you building yours from?

[PeterF]

Richard, Manish,

The RX is between the control box sides in the front seat foot well with both the antennae mounted in that location at 90 degree to each other. I use Hitec radio gear and although this is a 4 channel model, I have used the Optima 9 channel receiver that has two antennae for extra signal security.

The small box near the dummy exhaust is the telemetry sensor station, I have monitors on flight battery voltage, radio power voltage and current. See photo below.

I have not said much about the electrical side of my model other than the motive power side. On the Hitec receivers you can power the receiver separately to the servo power bus which with the advent of 2.4GHz and digital servos means that I always power the Rx function direct from the flight battery (it can handle about 35 Volts) and the servo bus from the BEC function in the ESC or from a separate BEC and you could never brown out with Hitec. You also get telemetry of the flight battery voltage without any other sensors. When 2.4GHz was new, this was quite an advantage, but it is now of course old hat. For larger models such as this, I install a back up battery supply, 4 cell Nimh, and have diodes between the back up battery, the BEC and the flight pack so I have dual power sources to both the RX function and the servo bus. I added the telemetry module so I can monitor both the flight pack voltage and the servo bus voltage. If I have a problem with the BEC, then the voltage drops from 6.0V to below 5.5V and I have a low voltage alarm. After 5 flights, I had used 200mAh from the 2500mAh back up battery. There are several threads on RC Groups about using diodes to create a back up system, I use 40Amp rated low voltage drop power diodes.

As the model is electric, there are no switches, everything is plugged in prior to flight. The right hand side cowl is fully removed and the cowl top is rotated open, still attached by the left hand side hine. I add the batteries and connect them onto the power harness, this power up the RX function but not the servo bus. I have an arming plug on the ESC supply and this is not in line at this point so no chance of the prop turning. I then connect the back up battery, which powers the servo bus, the ESC still being disconnected. I then put the top of the cowl down and replace the right hand side Cover and clip it down with the side catches. I check that the throttle is closed and the throttle hold is set. When I am ready, I then reach under the cowl with my arm outside the prop disc and fit the arming plug, only now does the ESC go through its arming sequence. There has been a discussion about arming plugs on this forum recently, very good and it made me decide to add one. This is especially because once the batteries are in and connected, there is a lot of work to do to close the cowl, all within the prop arc, hence leave arming the ESC till last. I had though about doing some work on the cowl top so that this was held on differently so it could be removed by itself to make this easier, but the arming plug was the easier choice.

The cowl open ready to receive flight batteries

View showing the back up battery connector (Deans), the telemetry station adjacent to the Dean connector, the current sensor can be seen on the red wire at the left.

View showing the arming plug from underneath

Arming plug installed (but no batteries for this picture)

The cowl sides are indeed held closed by spring loaded catches. These are made from 2mm threaded end push rods with a small washer and nyloc nut to hold the spring in place. I made the P shape ends on the catches and silver soldered them closed, just in case. I filed the grooves into the cowl to make sure that they latch closed securely and in fact I have to have a small tool I made up, piece of dowel with a hooked piece of piano wire in to open and close these catches. Old photo before I electrified all my models.

to be continued (due to post limits being exceeded).

[PeterF]

Richard, Manish,

The control throws are not on the plans, they are on the 4 pages of construction notes.

• Elevator 1 5/8" up and down
• Rudder 2 1/2" left and right
• Ailerons 1" up and 1/2" down

I have used the elevator and rudder throws as quoted. However, I have used the scale throws for the ailerons which I translated to 2 1/4" up and 1/2" down. Chris Stewart quotes the ailerons as being soft, however, in my test flying with my model, which has a lot more up aileron, I have found a positive aileron response which at full stick gave a good but not fast roll rate. Of course, mine also matches the full size in that as the stick goes to full travel, the down going aileron starts to return to the neutral position, so at 2 1/4" up aileron one side, I have very little down aileron on the other. There is lots of stuff on the design of my ailerons around pages 12, 13 and 14.

Edited By PeterF on 16/05/2018 13:50:03

Edited By PeterF on 16/05/2018 13:51:14

[Manish Chandrayan]

Thanks for confirming the the throws Peter

[PeterF]

Here are some still taken from a friend's video camera, I'll get the video added later. These are after the hinge lines had been sealed

[Richard Thornton 2]

Posted by Manish Chandrayan on 16/05/2018 13:28:39:

Posted by Richard Thornton 2 on 16/05/2018 12:32:54:

Hi Manish

The throws on my model plans are missing so I am using the throws as per the full size, but not sure your question was aimed at me.

Hello! Richard, the question regarding throws was for Peter. The Falcon kit instructions mention the throws. What kit are you building yours from?

Hi Manish and Peter

I am building the Traplet Duncan Hutson 1/4 scale moth. Many thanks for the details on the throws Peter. The full size scaled down are even larger than your models throws so i will work from yours.

Peter. I have been thinking about your plane climbing under little power, ie you said you were having to force her down. Could it be that due to no fuel , ie electric, she is tail heavy and that might explain why she is also supper sensitive to control surface inputs. I know from bitter experience that the further back the cofg is the more underwear changes are required. I prefer a little foward of the cofg, taming the beast until confidence is built up. No 3d flying for me.

[Manish Chandrayan]

Lovely pictures Peter and nice blue skies to fly

[Manish Chandrayan]

Richard, great kit to build. I had bought the plans and was planning to build that but then the Falcon kit came along and I picked up that. Are you doing a build log?

[PeterF]

Posted by Richard Thornton 2 on 17/05/2018 11:09:04:

I am building the Traplet Duncan Hutson 1/4 scale moth. Many thanks for the details on the throws Peter. The full size scaled down are even larger than your models throws so i will work from yours.

Peter. I have been thinking about your plane climbing under little power, ie you said you were having to force her down. Could it be that due to no fuel , ie electric, she is tail heavy and that might explain why she is also supper sensitive to control surface inputs. I know from bitter experience that the further back the cofg is the more underwear changes are required. I prefer a little foward of the cofg, taming the beast until confidence is built up. No 3d flying for me.

Richard,

I wanted to build the Falcon Models kit but I had something else on the board so I kept putting off the purchase decision. Then when I came to buy it, Chris had stopped selling the kits so I bought an unstarted Duncan Hutson kit but did not have the time to start building it. Then Chris started selling his kit again, so as soon as he was back in business I snapped one up and sold the Duncan Hutson kit, luckily selling it for what I paid. However, I did buy wheels and tyres from the Hutson Kit as they are scale items, unlike the ones offered with the Falcon Models kit.

Anyway, in terms of the CoG, I am slightly forward of the required point because the location on the plan will be for an empty fuel tank so with the batteries in I can go forward slightly. When I set out converting it to electric I did a proper force balance around the CoG by calculating the torque of each component around the CoG using the weight and distance from the CoG. I summed the torque of the full fuel tank, throttle servo and Laser 150 compared to the electric motor, ESC and flight batteries, which then fixed the flight battery location, because I fixed this before I had completed the build to then arrive at the flight battery location by trial and error. And I can say it has worked out.

It may be that in fact I was bringing the model in at a higher throttle setting than I thought I had because of a nervousness to go too slow. Now I have done the stall test I have found quarter throttle needs up elevator, which means that the plane will sink of its own accord, I was probably not going this low to start with. I have now added a tickover switch at 1,500rpm using the idle down function so that I can not actually go too far and know I will always have some prop wash for the final flair out and landing. Being more confident about the low end performance will mean bringing it in with less throttle, which I believe will help the approach.

I also want to check the motor mount I constructed to see if I have got accidentally added some down thrust, but I am going to leave this one alone until I have built up some more time in the air..

[Richard Thornton 2]

Posted by Manish Chandrayan on 17/05/2018 11:19:10:
Richard, great kit to build. I had bought the plans and was planning to build that but then the Falcon kit came along and I picked up that. Are you doing a build log?

Manish, no i have not done a build log, i started it that many years ago that forums like this were not possible, BUT you and PeterF have given me the urge to crack on and do some catching up of my own.

I might actually start a part build log now that this is possible, i enjoy the feed back and the fact you are able to ask like minded folks questions

[Manish Chandrayan]

Richard go on do it. We would love to watch another Tiger come along. I started my Falcon kit about 7 years back and still not complete. That should give you some solace

Yes the fact that others are able to advice and help is a big plus of doing a build log and asking when required. I have received and really appreciate all the help from folks on this and other forums

[Richard Thornton 2]

Posted by PeterF on 17/05/2018 12:33:26:

Posted by Richard Thornton 2 on 17/05/2018 11:09:04:

I am building the Traplet Duncan Hutson 1/4 scale moth. Many thanks for the details on the throws Peter. The full size scaled down are even larger than your models throws so i will work from yours.

Peter. I have been thinking about your plane climbing under little power, ie you said you were having to force her down. Could it be that due to no fuel , ie electric, she is tail heavy and that might explain why she is also supper sensitive to control surface inputs. I know from bitter experience that the further back the cofg is the more underwear changes are required. I prefer a little foward of the cofg, taming the beast until confidence is built up. No 3d flying for me.

Richard,

I wanted to build the Falcon Models kit but I had something else on the board so I kept putting off the purchase decision. Then when I came to buy it, Chris had stopped selling the kits so I bought an unstarted Duncan Hutson kit but did not have the time to start building it. Then Chris started selling his kit again, so as soon as he was back in business I snapped one up and sold the Duncan Hutson kit, luckily selling it for what I paid. However, I did buy wheels and tyres from the Hutson Kit as they are scale items, unlike the ones offered with the Falcon Models kit.

Anyway, in terms of the CoG, I am slightly forward of the required point because the location on the plan will be for an empty fuel tank so with the batteries in I can go forward slightly. When I set out converting it to electric I did a proper force balance around the CoG by calculating the torque of each component around the CoG using the weight and distance from the CoG. I summed the torque of the full fuel tank, throttle servo and Laser 150 compared to the electric motor, ESC and flight batteries, which then fixed the flight battery location, because I fixed this before I had completed the build to then arrive at the flight battery location by trial and error. And I can say it has worked out.

It may be that in fact I was bringing the model in at a higher throttle setting than I thought I had because of a nervousness to go too slow. Now I have done the stall test I have found quarter throttle needs up elevator, which means that the plane will sink of its own accord, I was probably not going this low to start with. I have now added a tickover switch at 1,500rpm using the idle down function so that I can not actually go too far and know I will always have some prop wash for the final flair out and landing. Being more confident about the low end performance will mean bringing it in with less throttle, which I believe will help the approach.

I also want to check the motor mount I constructed to see if I have got accidentally added some down thrust, but I am going to leave this one alone until I have built up some more time in the air..

Well Peter you have done the homework there. I know electric flight is totally different from ic particulally as you say on tickover and low speeds. Makes perfect sense what you have done. Now the weathers improved your going to get a chance to get some flight time under your belt. Have fun as you have really earned it .

[PeterF]

Out flying again today and I have settled on a pseudo tickover of 1950rpm set by trial and error. This is the first electric plane where I have the need to have a tickover set. The landings are much more predictable now and no more nosing over as there is always enough air flow over the elevator.