RC Modelling the Avro Arrow

Bob Parkinson Arrow	A New Ducted Fan Model
Arrow Airfoil Info	Arrow 2000 and CBC Movie Model

There was one available kit of the Avro Arrow for ducted fan flight. This was the Bob Parkinson Model Kit. Although it is rumoured that Bob still exists, he has evidently moved to the United States, and is no longer the Home of the Arrow. Don Britton writes that Bob does still exist. These are his words:

I am an avid ducted fan flier.  I have some information on Bob
Parkinson.  Yes, he has moved to the U.S.  Here is the address...

Bob Parkinson Flying Models
1140 Early Drive NW
Palm Bay, Florida
32907
(407) 726-8401

He offers the ducted fan Aero for less than $200.00 U.S.  Hope this
helps you 
out.                                                                 

The following description is the HTML'd version of a message sent to a gentleman working on a 1/6th Arrow powered by two 40lb thrust jets. Good Luck. I'll keep you posted, and they are working on a web page

OK,  You asked so here it is....

     You are right the Arrow did use a NACA 0004-6-3.7mod airfoil
(according to Arrow, by the Arrowheads anyways).

     The ultimate reference on this stuff is Theory of Wing Sections,
by Abbott and von Doenhoff. (its about $21 at your friendly neighbourhood
bookstore).

     So, I looked it up, because I have always been interested. Here's
the breakdown.

     The airfoil is a NACA 4 seried (that means 4 digits in its
designator). So, the airfoil starts life as a NACA 0004. The first two
zeros means its symmetrical, the 04 indicates the section thickness as a
perctentage of the chord. There is a formula in the book to generate the
ordinates (and there are several on the 'net). Now comes the interesting
part. As best as I can tell, the designator should be NACA 0004-63.7mod,
without the extra dashes. The first digit after the dash indicates the
leading edge radius. A six is the normal leading edge radius. For
information, a sharp leading edge would be a 0, a fat an 8. The leading
edge radius varies as the square of this number through this range. The
second number (Theory of Wing Sections only recognizes it as an integer,
but we can squint) indicates the position of the maximum thickness in
tenths of the chord. So, in our case we have a NACA 0004 airfoil with
normal leading edge radius and a maximum thickness at .37*chord length.

Boy, that was fun, eh? Now. The mod indicates the drooped leading edge.
This is not work documented in the book I have, and most likely indicates
the Avro engineers took some liberties. The section shape is shown in the
3 views in Arrow by the Arrowheads.

I have some further information from Design Progress, May 1959. The
article indicates that the leading edge was drooped by 8 degrees inboard
of the notch and by 4 degrees outboard of the notch. The notch is 'about
a 5% notch at about midspan' and the outboard leading edge has ' a 10%
increase' I presume they mean in chord. This chord increase is to cure
pitch up. For information, the notch creates a vortex that limits
spanwise flow. (Originally tried by English Electric, if I remember
correctly). It was found that the depth of the notch was the most
critical parameter.

Now, to add some more information to the pile. There is a BASIC source code program available that will produce this airfoil section. I haven't tried it extensively (been too busy), but it is available at The UIUC Airfoil Data Site. This is an incredible site that has thousands of airfoil sections in files, as well as utilities to view and manipulate them.

The file to look for on this page is David Lednicer's NACA.BAS program. It will compile nicely in QuickBASIC 4.5, and will run in QBASIC that comes with MS-DOS.
I also have a program available to view airfoil files, and it is a quick and dirty attempt (I wrote it to be able to sort through the numerous files around). Right now it is quite picky about its file format (most of them are), but the next revision will make it able to read a multitude of file formats. The ViewFoil program is available compiled to run on MS-DOS computers. Instructions are included.

John and Michael Houghton have been working on an RC ducted fan Arrow that sounds splendid. I have included here the full text of their letter to me. Since these letters were written to me, the Houghton's have created their own page. See it for more Arrow Model Details

John & Michael Houghton
35 Eighth Street
Collingwood, Ontario
L9Y 2C4
(705) 445-7869
EMail: houghton@georgian.net

R. K. Schmidt:

We're new to the Net and have just recently found your page re the Arrow. Michael, my son, and I fly radio controlled model aircraft and we wanted to go faster. Michael got turned onto ducted fans or jets but, like me, wanted something different to the standard F-16, 18 etc. He somehow saw the Arrow and we both knew that it was for us. This past two years we have been building a scale model of the Arrow and last fall we had two successful flights.

I don't know how much you know about model jets and how they are powered but we use a Ducted Fan setup. A small 2 cycle internal cumbustion engine turns a 9 blade prop inside a duct. These motors are high precision as they are reving at 20,000 rpm. The duct is 5 inches in diameter and with proper ductwork, the powerplant can produce 10-12 lbs. static thrust. Many jets are getting bigger and depending on the size and wing loading, guys are getting 15-20 lb. aircraft into the air and have them fly very well.

The Arrow that we are building is 1/12th scale. Length of 78 inches, wingspan of 50 inches. Fuselage is of moulded fiberglass and the wings are made of a blue foam core with balsa wood and fiberglass skin. Unpainted weight is 13.5 lbs and it flies like a dream. This is a typical building method for jets nowadays. I made a plug of the Arrow , a static master shape, and then made a fiberglass mould from the plug. I then laid fiberglass into the mould and when it was dry, I pulled it out and there is my fuselage. With the mould I am able to make as many fuselages as the mould will hold up to. After talking to some enthusiasts, I feel that I will be able to go into production and sell the kits to other modelers.

To produce the plans that we used, we relied on the Arrow Book by the Arrowheads. Photocopy enlarged the plans in the book until they really fell apart and then measured the drawings. Then Michael took these measurements and created our AutoCad plans. We are about 90% scale. At 1/12th the fuselage needed a slight bulge in the middle to take the powerplant. Also the wing is so thin that in order to give me some room to put in the retractable undercarriage, I had to increase the thickness about 10%. The undercarriage is home made from aircraft aluminium and aircraft steel. Air operated cylinders raise and lower the mechanism as it twists to fit into the wing, as the real one.

This project started out as a 'lets see if the model will fly and can I do the project'. Usually, when an aircraft is scaled down so accurately it has trouble flying, due to the difference in airspeeds, scale effects and reynolds numbers of smaller and slower wings. My goal from the start was - if it worked we would go to a larger twin engine version. Well this version works so well, that it looks like I have to sell the kit so that others can enjoy the Arrow as I go onto building the next size up. A 1/10th true scale with twin ducted fans, or if I had the money, I would power it with real turbine engines.

Yes that is right, there are now model size turbine jet engines and they are truly awesome. Some are propane powered, some are jet fuel powered. They are about 4-5 inches in diameter and 12-18 inches long. Produce anywhere from 8 to 40 lb. thrust, depending on which one of about 7 different versions you buy that are now on the market. Prices start at about $3000.00 U.S. up to $5000.00 U.S. Know any rich sponsors that would like to fund a Twin-Turbine powered Arrow Project???!!!

Next step the CF-100 or how about a Jetliner???

I have seen the Bob Parkinson Arrow, in fact it was photo featured in a recent model magazine as it appeared at a Jet Rally in Texas last September. It is not to scale, what is jokingly called 'Stand Way Off Scale'. Fuselage is short compared to the wing and it is not a scale wing, no notch, no undercamber and not to scale undercarriage. But it is available, he lives in Florida and does advertise under Bob Parkinson Models. Best bet for interest is to look up recent issues of Model Airplane News or R.C. Modeler, available at your friendly neighbourhood Hobby Shop.

There is also RL-206 hanging in a Hobby Shop in Orleans in Ottawa, Shop name of Discount Hobby. Again Ducted Fan about 1/12th Scale. It is sort of scale and the trained eye can see many variants. Apparently the builder got too happy with the fiberglass resin and the thing is too heavy. Never been flown although the powerplant, and all is in the model.

I have heard rumour that a chap in either Winnipeg or Calgary, they are so close together, is trying to produce a kit of the Arrow. Don't know much more than that, other than I think his business name is Celler Dweller Hobby's. I heard this at a big Hobby Show that happens every April in Toledo, Ohio. It is THE show to attend either as a modeller or a supplier of Hobby equipment. I was telling lots of people down at the show that I was building an Arrow and to my surprise some of the Americans actually knew about the plane.

I can't get into too deep a conversation about the Arrow with anybody as it makes my blood boil at how stupid our government is when it comes to the aircraft industry in this country. The loss of the Arrow is only a small piece of the puzzle that is gone for ever, when you think of how good an industry was there in Canada and our Government 'LEADERS???!!!" have over the years just killed the whole industry.

Well I think that this might be enough rambling. We really enjoy your page and would like to thank you for taking the time to put it together for others to see.

This may be too much to send to you but I have appended a newsletter to this note to you. I have collected a list of names of people that have expressed an interest in purchasing a kit from me when it finally becomes available. I forwarded this newsletter to those people last fall, after the flights. Some of the info is repeat of what I said to you above. Some of it is directed to model jet flyers so if it makes no sense to you I hope you are tolerant of me.

Thanks again

John & Michael Houghton

Dear Arrow Enthusiast:

THE ARROW HAS LANDED!!!

We were at Quinte 1995 with our Avro Arrow CF-105, and you had expressed an interest in our jet at that time. We promised to keep in contact as thing progressed and until now, not much of news worthiness has occurred. It has taken all of the summer to bring what you saw at Belleville into flyable shape. This project has been bigger than anticipated.

Taxi trials occurred on Sunday afternoon August 27, 1995. Plenty of power and the fan picked up revs as the plane accelerated. Good ducting design I am told.

Monday September 4, 1995 was maiden flight day. Good static thrust lead me to believe that liftoff would easily occur. Was going to try a couple of taxis but when throttled up, the jet responded so well within the first 50 feet that I decided to go for broke. Held it on for a good 200 feet on paved runway then pulled back and crossed my toes. Observers said that it "Leapt" into the air. There was some left roll that needed trimming out and some tense moments to adjust to the extreme sensitivity on the ailerons but it flew and flew beautifully. Both high and low speed passes were very stable. The Arrow penetrates the wind very capably and will perform to the max. 6 minutes of flying and time to setup for a landing. Approached fairly high and what I thought was slow enough for a jet. Handling at medium-slow was very stable at about 30 % power, nose was not too high and had a good sink rate that could be easily controlled. On a go-around it came back up on the power very quickly. Reset for second approach and downwind was stable and level. Brought it in slower but not a high enough angle of attack as on flair it ballooned and stalled and pranged in from about 6 feet. The right main bogie arm bent and jammed the tires thus applying a full right wheel braking effect. This swerved the aircraft right and the 20 m.p.h. breeze got under the left wing and flipped the Arrow on its back. Some damage to the fin, right wing upper surface and the fuselage but all was repaired easily.

Saturday, September 23, 1995 second flight day. Mechanically reduced the aileron throw to 12 degrees and put in a low rate on the radio of 8 degrees with lots of exponential ( -38 and -44 on my Futaba Super 7). Reduced the elevator to 15 degrees high and 10 degrees low with moderate exponential. Stupidly I didn't mechanically reduce the rudder throw but left it at 20 and 15 degrees. A heavy duty five cell battery was installed which moved the C. of G. about 3/8" forward. Take off was smooth as I pulled back on the stick sooner and it flew into the air. Climb was very good and all the erratic behaviour of over sensitive aileron was gone. However, because I left the rudder with too much throw, it not only yaws the plane to great authority, it also severly rolls the plane. This could have added to my problems on first flight as I am used to flying with rudder and instinctively correct with both sticks. Rudder is now mechanically fixed at 12 degrees high rate and I am sure this will be enough. Forcing myself to fly only aileron/elevator the jet is very smooth, goes where you point it and does what you tell it to do.

Both high and low speed passes were rock stable in the 15-20 m.p.h. breeze. The plane wants to fly. 40-50% power and pull up slightly to slow the plane down and all it does is climb.

After rereading all the Jet International articles on landing deltas I thought I knew what to do on landing but not so. First attempt was far too hot with too much power left on, about 30% after turn to final at 100 feet up. The Arrow didn't want to sink. Chopped to idle too late to really slow down enough. Flair was nose very high ( about 20 degrees up) and I applied power from idle. The Arrow climbed into the air with no hesitation ready for another attempt. However, I wasn't ready, and I repeated the approach the same way just a little lower. Still too hot and too much power left on for too long. I did get it down ... hard, but not too badly hurt. We did have it on video tape though, and watching the film after, the landing procedure is obvious. On the down wind, trim for level at 50 % power. The power is needed to get you through the turns as sink is pretty quick if there is not enough. (Power, not necessarily speed.) Stay high and after the turn to final, immediately chop to idle. Pull the nose high to slow way down and then adjust the glide with power. The video shows that once I got to idle, I could pull the nose up without the chance of ballooning, and still maintain control. Touchdown will be nose high ( 20 degrees ?? ) and surprisingly slow once the proper technique is accomplished.

Flight configuration:

Ramtech Fan, O.S. 91 DFVR and J.H.H. twin tuned pipe. Fixed wire undercarriage, fuselage unpainted weight 13 lbs. Estimated high pass speed 90- 100 m.p.h. This is with big open wheel wells in wing and undercarriage down. With retracts, doors and all cleaned up should hit 150 m.p.h.??? I'd like to paint it before next test flights as visibility in epoxy beige is pretty low but I also want to get in as much flying this year as possible so that I can really know what to adjust for next year and for the kit. (2nd flight had a dayglow red vertical fin and it helped alot.)

Over the winter the retractable undercarriage will be finished and some changes need to be made to some moulds. While the ducting seems to perform well, it is a bit of a bear to assemble so work on a splitable mould is needed. I am also seriously considering moulding the wings rather than sheeted foam. The profile is very difficult to cut and assembly of the wing is complicated. Moulded wings could be honey-combed, allowing for an undercarriage support spar, and a great deal more strength.

This has been a richly rewarding experience for both Michael and myself. We thank you for expressing an interest in our project. You will probably get one more letter in the spring to let you know how the winter fine tuning has gone then we hope to meet you again at Quinte 1996. Until then, have a constructive winter.

John & Michael Houghton

Kyle,

1. Yes we have fiberglass shells available. The idea is to sell the entire aircraft structure as a kit complete with fiberglass fuselage (2 halves to be joined), foam-core wings and fin, custom undercarriage (perhaps optional for the modeller not wishing to spend the extra money for custom retracts), complete ply-wood formers, ductwork, and blue-prints, photos, etc, for finishing details. We are currently at the stage where we need to fly the aircraft in order to determine if any changes need to be made for production. We already have a few in mind and it is just a matter of time before a kit will actually be available.

How much you ask? That's a good question. Moulded fiberglass models can sell for anywhere between $400 and $1200. There is of course some fluctuation in scale looks, and kit completeness and complexity to mirror the fluctuation in price. The final price of our Arrow has not yet been determined but we have estimated that a price of about $800 for the kit would be fair. The cost of the materials alone is fairly high when you consider the fiberglass, carbon fibre, epoxy resin and woods that go into it. Again, this price is not finalised. We still have to take into account the price of the custom undercarriage. It is common for companies to charge in excess of $400 for a set of undercarriage given the many hours required to cut the pieces out on a mill or lathe. Our undercarriage has been designed to keep the time required to build at a minimum and they should not cost more than $400. The undercarriage price may also indirectly effect the price of the airframe kit. It is intended to sell the airframe seperate from the undercarriage so that if a modeller wishes to stay with a fixed undercarriage, it is still possible to do so.

This just in... Check out John's site for the details, but the intro price of the kit including main gear is $850

Doug Hyslip of R/C Hangar in Calgary has created and flown an eighth scale Arrow for the upcoming CBC movie The Arrow. Pictures are available at the Arrow 2000 site. This is what Greg Greene has to say:

Just to let you know that Doug Hyslip of R/C Hangar in Calgary
has been flying his 1/8 scale model for a few months now in
preparation of the CBC filming.  It uses 2 K&B 100 ducted fans
for power and weighs approx 40 lbs.  Its quite a sight and I am
going to be trying to put some video clips on for down loading
        The model flies well and at a deceptive speed due to its
size.  It is built from fiberglass molds and foam wings, any one
interested should contact Doug at arrow@quenet.com