Storm Petrel XL 200% 108" Wingspan

[Geoff McVey]

After a lot of thinking have decided to build a XL version of this model. The Storm Petrel was designed by Tad Davidson and an article appeared in RCM&E in March 1991, I have built a couple of these models, one with a .20 two stroke engine as the plan suggests, the second model was an electric version, can't remember the size of the electric motor, bur flew just as good if not better than the two stroke version. With this XL version over the last week have studied the plan in great depth as how best to build it and with what size balsa sheet, balsa strip wood, lite ply etc. The wing has no ailerons, should I build another wing but with less dihedral. Not sure yet what the weight of this model will be, but have a spare Zenoah 38cc engine which I think will be ideal. One question I have at the moment, on the original plan the U/C was made from 8 SWG wire, I'm guessing to make the U/C much stronger, maybe from 6mm - 8mm sheet aluminium, if so where would be the best place to get this made. I do have many more questions on this project, but will try not to ask too many too soon.

I could give a description of how the original model was built with ply, balsa sheet and balsa strip, and what I think maybe the right choice and selecting ply and balsa for the XL version.

Flying the original Storm Petrel has been such a joy, so much so, remember when taking my A certificate test, had a dead stick landing for real, a very nice smooth landing.

I have also been speaking to the Editor of RCM&E and hopefully get an article in the magazine at some point, maybe in the LMA Journal.

Will welcome any comments or advice on building this project.

[John Greenfield]

Don't make the undercarriage from Aluminium. It is heavy and will fatigue quickly. It will also need substantial mountings in the fuselage to secure it.
Look at the piano wire undercarriages on the SD Greenley http://www.ghostsquadron.co.uk/greenley ... _page.html Greenley / Lowley fuz. It is simply made from 1/4" piano wire with a 6swg rear brace. Take special note of the fuselage mounting which puts all the loads on the fuselage sides and it is impossible to knock it off the model in a bad landing.
The design has been tested for years in Greenleys used as glider tugs with thousands of landings.

[Geoff McVey]

Hi John,

Thank you for your post, will take on board what you have suggested and take another look at the SD Greenley U/C. Because the U/C on the SD Greenley has been tested for years and thousands of landings, makes sence to make the same U/C.

Where would it be possible to get a U/C made for this project, is there any LMA member on here that maybe able to make this, or any particular UK modelling specialist, otherwise will have to make this myself.

[Geoff McVey]

Zenoah 38cc engine mount placed over F1 firewall.

Zenoah 38cc engine mount attached to the engine then placed over the firewall.

[Geoff McVey]

Cowling side panel showing engine thrust line, placed next to F1 firewall.

Zenoah 38cc engine mount placed on the fuselage side view, along the engine thrust line.

[Geoff McVey]

Zenoah 38cc engine attached to the engine mount then placed over the fuselage side view, tried to get good overall view but have show directly over the top, then one from back of the engine mount then another from the front.

This photo showing the engine mount on the firewall.

This photo showing the of the prop attachment, looks like a good fit.

[John Greenfield]

Hi John,

Thank you for your post, will take on board what you have suggested and take another look at the SD Greenley U/C. Because the U/C on the SD Greenley has been tested for years and thousands of landings, makes sence to make the same U/C.

Where would it be possible to get a U/C made for this project, is there any LMA member on here that maybe able to make this, or any particular UK modelling specialist, otherwise will have to make this myself.

Geoff
The Greenley undercarriage is a very simple wire bending job. The top 90 deg bend on the main legs can be assisted with some heat but all the other bends should be done cold to avoid taking the temper out of the wire. I have been bending this type of undercarriages for years with just s simple wire bender and a vice. Have a go, it is easier than you think.
John

[Geoff McVey]

Geoff
The Greenley undercarriage is a very simple wire bending job. The top 90 deg bend on the main legs can be assisted with some heat but all the other bends should be done cold to avoid taking the temper out of the wire. I have been bending this type of undercarriages for years with just s simple wire bender and a vice. Have a go, it is easier than you think.
John

John,
Yes, the U/C looks simple enough to make, main reason for asking if there is anyone out there or any website that maybe able to make this U/C is I don't have the facility to take any temper out of the wire, and also currently don't have a vice.
Geoff

[Geoff McVey]

This is a 500cc fuel tank that I have, should I place a bigger one in for the Zenoah 38cc engine.

[Geoff McVey]

I have attached the engine mount, silencer, Graupner 20" x 10" prop and spinner over the fuselage side view, to see how this fits.

[John Greenfield]

Geoff
The Greenley undercarriage is a very simple wire bending job. The top 90 deg bend on the main legs can be assisted with some heat but all the other bends should be done cold to avoid taking the temper out of the wire. I have been bending this type of undercarriages for years with just s simple wire bender and a vice. Have a go, it is easier than you think.
John

John,
Yes, the U/C looks simple enough to make, main reason for asking if there is anyone out there or any website that maybe able to make this U/C is I don't have the facility to take any temper out of the wire, and also currently don't have a vice.
Geoff

Geoff
Cant help with the vice problem but you can take the temper out of the wite to make the top 90 deg bend just by holding the wire over the flame of a gas cooker and heating it up locally that way.

John

[John Greenfield]

This is a 500cc fuel tank that I have, should I place a bigger one in for the Zenoah 38cc engine.

With a Zenoah 38 in that model, which will not need anything like full power to fly, a 500cc tank will last for ages. No need for anything bigger.

John

[Alan Cantwell 1131]

If you give me the width of the aircraft, I do have several composite undercarriages,

[Geoff McVey]

Geoff
The Greenley undercarriage is a very simple wire bending job. The top 90 deg bend on the main legs can be assisted with some heat but all the other bends should be done cold to avoid taking the temper out of the wire. I have been bending this type of undercarriages for years with just s simple wire bender and a vice. Have a go, it is easier than you think.
John

John,

I have not ordered my wood yet, going to wait until SLEC are back open and wait until customers are allowed back, I very much like to select my own wood, but say that, if the lockdown continues for some time I may just have to order online, when you select your own wood at SLEC, not 100% sure but think you get a 10% or 20% discount.

Near the time of making the U/C, I may just have a go at building it, but at the same time may look at any other options.

Geoff

[Geoff McVey]

This is a 500cc fuel tank that I have, should I place a bigger one in for the Zenoah 38cc engine.

With a Zenoah 38 in that model, which will not need anything like full power to fly, a 500cc tank will last for ages. No need for anything bigger.

John

John,

Thank you for your advice here, thought that I may need a bigger tank, maybe 1 litre, but as you have suggested will stick with the 1/2 litre tank that I have.

Geoff

[Geoff McVey]

If you give me the width of the aircraft, I do have several composite undercarriages,

Alan,

Below are some photos that I have taken of the U/C and some dimensions, hope that this may help.

This first photo showing F2 and F3, F2 is 6 1/2 inches wide, plus 1/8 inch lite ply fuselage sides making a total fuselage width at F2 as 6 3/4 inches. F3 also has the same width as F2.


The second photo below is a fuselage side view showing the location of both F2 and F3. If you look at the lower left side of the photo just to the right of F2 and below the ruler you'll see 2 vertical lines, these lines are where the collets would be placed to secure the U/C.


The third photo below shows both side and front view of the U/C. Looking at the side view at the top where the collets would be placed to secure the U/C this length is 5 inches, then there is a bend from the top of approx 5 degrees, this length going down to the wheel is 11 inches. Looking at the front view of the U/C, the top has a width of 4 inches, where the U/C legs come out at a angle of approx 45 degrees, the length here is 15 inches, and again the last bend of approx 45 degrees where the wheels will go this length is 2 3/4 inches.


The last photo below is showing the tailwheel unit, please let me know if you have anything suitable here, if you don't have anything suitable, not a problem, will then have to make my own U/C as John Greenfield has suggested.


Hope all this makes sense and with the dimensions that I have given.

[Alan Cantwell 1131]

I will have a look,

[Geoff McVey]

I will have a look,

Thank you.

[Alan Cantwell 1131]

At last, I have found this carbon undercarriage, more details soon, take some measurements,

[Alan Cantwell 1131]

Sorry, nothing like yours, it’s very thin at the fuselage, and very long, looks like it’s a scratch build,