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OZPAF
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« Reply #175 on: May 10, 2020, 08:53:11 PM »

That's looking pretty neat Chris. It would look something with the original colours and lettering. Perhaps it's too good for a Swing model. Smiley

Stay safe - have fun.

John
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sx976
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« Reply #176 on: May 12, 2020, 02:17:12 AM »

Yes, I'm going to do it very similar to the original. Red fuselage and wing tips, clear doped wing and the red letters with shadowing if my daughter can make them on her Cricut.

My son asked if it was possible to put a motor in it!! Too good for whip control, he said.

I realized that the bearing tube for the prop I had designed was nothing other than a shaft and tube assembly for a model boat!! So I have ordered one.

Next job, the cowl.

Chris P
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sx976
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« Reply #177 on: May 14, 2020, 01:38:45 AM »

This is the new idea for a spinning prop using a model boat propshaft as a bearing. I am very pleased with the result.

Chris P
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sx976
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« Reply #178 on: May 16, 2020, 03:14:38 AM »

Yippeeee!!! The field is open to flying again so we took a picnic, the 3 HQ Airgliders and the Dornier Delphin.

The HQ Airgliders had been trimmed in our sports hall, so there were no big surprises. Maybe a touch too 'floaty' for outdoors. I will do some ballasting experiments the next time.

The Dornier Delphin was tail heavy. I had set the CG at 30%, but that was too far rearwards. I taped on 35g of solder until it flew properly. When I got home I replaced it with lead weights inset into the underside of the float.

I learned an important lesson with this model. In the original 1967 article, Michael Payne stated that the limit for comfortable flying was 12ozs (340g). The Delphin weighs 325g and I can confirm that it's definitely getting close to the limit of comfortable flying. If you look at the photo of Jonathan flying it, it's plain to see that he is putting real effort into flying it. I have one heavier model, the P-47, which weighs 348g and hasn't flown yet. The lesson learned is that using up a couple of larger kits that have been slumbering in the cellar for Whip Control will no longer happen.

Chris P   
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OZPAF
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« Reply #179 on: May 16, 2020, 04:34:02 AM »

Nice photos Chris. The HQ Airgliders look very sharp against the blue sky! That is an interesting point re the weight Chris - I would have thought that drag would have been more of a limiting factor.

John
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sx976
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« Reply #180 on: May 16, 2020, 07:59:27 AM »

Nice photos Chris. The HQ Airgliders look very sharp against the blue sky! That is an interesting point re the weight Chris - I would have thought that drag would have been more of a limiting factor.

John

An excellent point, particularly considering the Dornier Delphin's lack of aerodynamic refinement. The spinning prop is surely not helping either. I intend to do some test flights and put some rough design goals together. About the sweetest flying model is my Alpha Jet - good aerodynamics with a flying weight of 140g including 40g ballast. Maybe the future is profile models or jets? Or profile jets!  

Chris P

PS : I have decided to test fly the Delphin without the spinning prop. It's only held on with a rubber ring prop saver. If there is a significant improvement, I'll abandon the idea of a spinning prop on the F2C model - which I was going to fit this afternoon!!!  
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sx976
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« Reply #181 on: May 18, 2020, 05:02:24 AM »

Re aerodynamic drag. I flew the Delphin yesterday with and without the prop. The reduction in effort without the prop was significant. I also took my most aerodynamic models - the F-18, F-22 and Polecat. These are small models weighing 79g, 83g and 53g respectively. I had no problem flying all three on 34 feet pole + line lengths and they would have easily flown on longer lines. Concrete proof of what we expected.

I also test flew the P-40 and F2C. Both models fly outboard wing low (a lot). Huge amounts of lead on the inboard wing are needed to correct this, which is obviously not a viable solution. I have the same problem on my Fake German Jet and the Brewster Bermuda profile. The only significant difference I can see is that models exhibiting this phenomenon all have zero-zero incidence. (The F2C just has a flat wing with no elevator cut out yet). So last night I converted the Bermuda to single line flying. I weighted it to get the CG at 25% MAC and will used the pushrod to trim up elevator and see if it then flies level. Most curious.

Chris P
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OZPAF
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« Reply #182 on: May 18, 2020, 05:23:07 AM »

Quote
also test flew the P-40 and F2C. Both models fly outboard wing low (a lot).

Do you think this may be a case of the line attachment on the model not being far enough forward( extended line of action going behind CG)? If it is a bit too far back then the model will tend to yaw outwards excessively and this may reduce the lift on the outside wing.

Dihedral or sweep on the wings would also make this effect worse.

John
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JugheadP47
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« Reply #183 on: May 18, 2020, 11:30:36 PM »

I just came upon this thread.  The first plane I ever flew was a whip plane.  I had gotten two of them by sending four box tops from Cheerios cereal. They were printed on heavy construction paper.  I cut out the pattern with a razor blade, and there were fold lines, and tabs to tape it together.  This was fifty to sixty years ago, so the memory is fuzzy.  I remember there were several options.  The two I got were the Me109, and Gruman Hellcat.  I think.  One may have been a P40. They were incredibly fun.  I still like Cheerios.
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sx976
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« Reply #184 on: May 19, 2020, 04:36:34 AM »

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also test flew the P-40 and F2C. Both models fly outboard wing low (a lot).

Do you think this may be a case of the line attachment on the model not being far enough forward( extended line of action going behind CG)? If it is a bit too far back then the model will tend to yaw outwards excessively and this may reduce the lift on the outside wing.

Dihedral or sweep on the wings would also make this effect worse.

John


Again great input from you!! I have been setting up the fuselage tether and tip guide at 1cm in front of the CG. The CG starts off at 30% MAC and then I trim with weight to get good performance. With the HQ Airgliders, due to the structure, the tether is about 3cms in front of the CG and they all fly fine. However I am a bit suspicious of using this setup for other models as they fly very slowly with little line tension.

I should be able to fly the Bermuda this afternoon and see the effect of higher pitch stability. The fuselage tether and wing tip guide are 1cm in front of the 25% MAC line, which is where the model balances. I want to try one idea at a time and the second one on my list was also tether position. The Bermuda has been sacrificed to these tests and I have no issues with doing whatever hacking of the model is necessary to get it to fly properly. Work on other models has been temporarily suspended!

Chris P

   
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sx976
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« Reply #185 on: May 19, 2020, 04:49:09 AM »

I just came upon this thread.  The first plane I ever flew was a whip plane.  I had gotten two of them by sending four box tops from Cheerios cereal. They were printed on heavy construction paper.  I cut out the pattern with a razor blade, and there were fold lines, and tabs to tape it together.  This was fifty to sixty years ago, so the memory is fuzzy.  I remember there were several options.  The two I got were the Me109, and Gruman Hellcat.  I think.  One may have been a P40. They were incredibly fun.  I still like Cheerios.

Nice story!!

I googled Cheerios and found this plane which came printed on the box. You didn't have to send away for it. We were satisfied with much less in those days!!

Chris P
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« Reply #186 on: May 19, 2020, 02:01:19 PM »

Just came back from the flying field. The Bermuda is now flying perfectly. I had dialled in 3mm up to compensate for the 25% CG and this proved just right. In fact the model flew a touch left wing low, which I think was due to the addition of the tether guide on the LH wing. I didn't have any lead weights with me, so I taped on a small key. This levelled things up beautifully.

I could only bend the fuselage tether forward about 6 or 7mm to see if there was any significant change to the yaw, but I couldn't detect any. I might add another tether that's maybe 2cm further forward to see what happens.

Good progress!!

Chris P
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JugheadP47
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« Reply #187 on: May 19, 2020, 06:39:03 PM »


Nice story!!

I googled Cheerios and found this plane which came printed on the box. You didn't have to send away for it. We were satisfied with much less in those days!!

Chris P

A little like that, but the ones I got, probably prior to 1965, had full fuselage, not profile. The wings had camber.  Don't remember if there were ribs or a spar.  I have searched for them, but never found them.  Maybe I'll try again.

Cheerios are a popular breakfast cereal here.
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OZPAF
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« Reply #188 on: May 19, 2020, 08:32:44 PM »

It's interesting to me to see how much is actually involved in fully understanding what appears to be a simple form of flying. it is the icing on the cake of model flying for me. So good luck with your experiments.

Fascinating bit of history Jughead - an era when kids could still get excited over simple forms of entertainment.

John
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« Reply #189 on: May 20, 2020, 01:08:07 PM »

It's interesting to me to see how much is actually involved in fully understanding what appears to be a simple form of flying.

That's exactly how I feel too!! I did get a BSc degree in Aeronautical Engineering a million years ago and, as you say, it's interesting understanding a form of flying which is not relevant to full size aircraft.

The poor old Bermuda was looking very scruffy with 60g of iron on the nose. So after helping me to find the solution for the outboard wing low syndrom, I cheered it up by boxing in the weights with scrap balsa and covered the whole lot with 0.4mm ply. I think it's a good solution for profile models.

Chris P
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« Reply #190 on: May 20, 2020, 01:13:07 PM »



A little like that, but the ones I got, probably prior to 1965, had full fuselage, not profile. The wings had camber.  Don't remember if there were ribs or a spar.  I have searched for them, but never found them.  Maybe I'll try again.

[/quote]

If you do track down these models, please post details here!!

Chris P
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OZPAF
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« Reply #191 on: May 20, 2020, 08:30:13 PM »

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I did get a BSc degree in Aeronautical Engineering a million years ago
Interesting Chris! Around the same millennium or perhaps earlier I started a course in BscAero Eng as well. My dream was to be a Aero Engineer. I didn't apply myself - too immature and ended up as an air conditioning design draughtsman instead.

I have had a insatiable interest in Aerodynamics since and studying it in any form is one of my main interests. thus my interest here on HPA in Free Flight trimming, design in general and the peculiarities of CL models.

CL has it's own unique features I feel, in it's form of "automatic pilot" operating through the lines applying the necessary elevator input to return the model to it's trimmed height. Also i recently found a reason why of all the model classes - the CG needs to be so far in front of the MAC, as this acts as  negative feedback to the "autopilot" effect.

There is far more to CL and it's cousin Whip Control, than meets the eye!

Cheers,

John
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« Reply #192 on: May 21, 2020, 04:53:25 AM »

I loved the structure side and this got me into the automobile industry at the time when crash testing started in earnest and mass savings became important.

Here's another datapoint. I checked the revised CG on my Dornier Delphin and it is at 25% MAC. It also has a healthy amount of negative setting on the tailplane. As this model flies very well, I will use this setup going forward. My first two questions on Whip Control were 'where's the CG' and 'where is the tether located'. I'm finally getting nearer an answer!!

If you're interested on how I determine the MAC on my models, there's a little article I wrote on Outerzone.co.uk under Viewpoint.

Chris P
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« Reply #193 on: May 21, 2020, 09:13:12 PM »

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I did get a BSc degree in Aeronautical Engineering a million years ago
Interesting Chris! Around the same millennium or perhaps earlier I started a course in BscAero Eng as well. My dream was to be a Aero Engineer. I didn't apply myself - too immature and ended up as an air conditioning design draughtsman instead.
I loved the structure side and this got me into the automobile industry at the time when crash testing started in earnest and mass savings became important.
I spent fifteen years as a machinist before getting my BSME.  Often wish I had stayed on the shop floor. My career focused on CAD work. Now interviewing for a drafting job. 2/3 the pay at my last aerospace job, and hopefully less than 2/3 the stress.
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« Reply #194 on: May 22, 2020, 01:43:56 AM »

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I did get a BSc degree in Aeronautical Engineering a million years ago
Interesting Chris! Around the same millennium or perhaps earlier I started a course in BscAero Eng as well. My dream was to be a Aero Engineer. I didn't apply myself - too immature and ended up as an air conditioning design draughtsman instead.
I loved the structure side and this got me into the automobile industry at the time when crash testing started in earnest and mass savings became important.
I spent fifteen years as a machinist before getting my BSME.  Often wish I had stayed on the shop floor. My career focused on CAD work. Now interviewing for a drafting job. 2/3 the pay at my last aerospace job, and hopefully less than 2/3 the stress.

Before I retired I finished up as a Project Manager running two car programs. One was in South Korea and the other one was in Detroit. The Koreans wanted to have phone conferences at 6:00 in the morning my time, and the Americans at midnight. I know what stress is !!! 
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« Reply #195 on: May 22, 2020, 02:10:46 AM »

Flight testing again yesterday. The Bermuda now flies superbly and joined the 34 club (flying on 34 feet pole + line). I must make up a longer line for the reel as there is much more potential there. It looks a bit naff flying without a prop, so I'm thinking about replacing it by an early post war straight wing jet such as a Grumman Panther. As the Bermuda is finally flying well, I may replace the bellcrank at a later date and try flying it again on two lines with a handle.

The Lidl Glider and Delphin both flew very well, but yawing to the right. After a year flying these darned things you start to notice the smaller details. I guess what has happened is that I have moved the CG forward on both of them and it has finished up about where the tether point is. I got up early this morning (lots of practice at that from running a Korean car program from Germany!!) and moved the fuselage and wing tip loops forward on both of them by 2cms. Relatively easy on these foamies. I think that the generic 1cm between CG and tether is too small for larger models and I also have the gut feeling that too small a distance is worse than one too large. 

The next step will be to test fly the P-47 and FW 190. As both have RC elevator, it will be easy to add noseweight and dial in up elevator trim if necessary. However I dread the thought of having to move the tether points on these painted models. The same goes for the P-40, which definitely has the OWL syndrom (one wing low), where I will most probably have to cut in elevators. Again, moving the tether points would probably mean much paint retouching.

The thought of moving tether points on the F2C is even worse!!

Chris P
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OZPAF
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« Reply #196 on: May 22, 2020, 05:20:37 AM »

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Insert Quote Flight testing again yesterday. The Bermuda now flies superbly and joined the 34 club (flying on 34 feet pole + line).

34' - that's good going Chris. I have an old 1cc Bee diesel powered semi scale profile Camel that flies on 35' from memory.

If the 2 line system can be made to work on that model without too much hassle - then it would be neat. Maybe groupers on the line would help keep the drag down - but that would make it hard to reel the lines in/out.

John
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« Reply #197 on: May 22, 2020, 05:24:50 AM »

Well good luck with that JH. I was "retired" in 2008 and don't particularly miss it apart from the money Smiley

John
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« Reply #198 on: May 23, 2020, 08:15:01 AM »

I found this Grumman Panther plan from the Spanish magazine Lupin on Pinterest. I printed it out scaled up just a bit to 18ins span, and it looks like a really sensible whip control model. Straight wings and a nice long nose. I would give it some down incidence on the tailplane and balance it at 25% MAC. I'll put it on the 'Maybe' List.

Chris P

Hey - I just made Silver Member. Yipppeeeee!!
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« Reply #199 on: May 23, 2020, 09:16:16 AM »

Another model surfaced from the back of the cellar when I was down there looking for something else. I had completely forgotten about it. Some 15 years ago I wanted to build a 'Catapult Solid' as per Aeromodeller January 1954. I chose the crescent wing Arado 234 V16, but got bored with the build after a couple of evenings. I found the model well protected in a plastic bag with the plans. A tiny thing, only 28cms in span. The wing was on the fuselage, but the engines and tail had not been fitted. Perfect!! I fitted the tailpane at negative incidence, then the fin and decided not to fit the engines at all. A few hours work and I had a single wing tether fitted and 5g in the nose to get the CG at 25% MAC.

I will see what it does the next time I go flying. If it's OK, I'll dope and paint it.

Chris P
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