Kevin Greene

My Feedback: (85)

I have been working with Robart to make functional oleo struts for the Avonds F-16. The tooling to make the struts is just about finished. Robart plans to make the struts sometime next week. Eric at Robart needs to know how many sets to make. All of you that need these struts need to either respond here or contact Eric at Robart directly. If you fail to respond now it will be a four to six week wait to get your struts once ordered at a later date. Once tooling for a particular strut is set up, struts are built as demand dictates. If you fail to get on the list now it will be some time before these struts come back into the rotation unless the demand gets high. (There aren't that many Avonds F-16's in this country)

I'm going to call Eric at Robart on Monday to tell him how many responded here.

Thanks.....Kevin

Tom Antlfinger

My Feedback: (24)

Hi Kevin:

I am starting out with stock wire struts, but put me down for a set.

Received a nice note from Philip about the pro/cons of struts with the near 45 deg strut angle on 16's. Very hard to spring since horizontal vectors=vertical vectors. If you get the spring too soft, then it will dip wing tips too easily and make tight turns and x-wind landings scary.

On hard surface, he really goes for the stock wire struts with softer tires or the upcoming scale set, but on grass, where I can skid the tires a bit more, I think the struts will be fine, if the wires prove too bendy.

Tom

mr_matt

My Feedback: (10)

What is the "no sh*t" status on that scale gear?


Thanks

pilot tw

PLS find the homepage for Main Wheels Break Set & Oleo Struts Legs of P. Avonds F-16..

http://web.my8d.net/skymasterjet/acc.htm

Kevin Greene

My Feedback: (85)

Tom,

I've heard Philip's pro's and con's too and I just don't agree with everything that he says. My background is mechanical/electrical engineering and I do understand where Philip is coming from. I have seen too many Aviation Design and Spider Jets F-16's fly (and land) to say that these angles will not work in conjunction with an oleo strut.

I can see problems with using Robart plastic wheels and the soft tires that accompany them. Even with the foam inserts these tires are waaaay too soft. Can you see that plastic wheel, not to mention the plastic bushing, holding up to a 20 plus pound aircraft on a hard landing??? Philip is relying on the soft tires to absorb the landing loads. With these tires you will also develop flat spots on them if the aircraft is left on its' wheels for any length of time. Just imagine setting those tires on the hot tarmac on a 100 degree mid-western day!!! The Europeans seldom have to deal with temperatures this high.

Eric at Robart is springing these for approximately a 24 lb plane. This should be stiff enough for X wind landings and other side loads. If they prove to be too stiff for some, a coil or two can be removed to soften them up as you like.

I'm not saying that I'm right----I just have a different opinion on this than does Philip.


Pilot TW,

Aviation Design and the Avonds F-16 have different strut angles as compared to each other. This is why Robart had to make new jigs/tooling instead of just using the Aviation Design jigs/tooling. Are you sure that your struts are the same angle as the Avonds struts? Also, Robart has you beat on price. Your struts do look good, though!!!

Kevin

pilot tw

yes, the Avonds F-16 and AD F-16 have different strut angles , Skymaster has make two degree for AD F-16 and PA F-16,

also for every order you must appointed which F-16 are you want?

Tom Antlfinger

My Feedback: (24)

Hi Kevin:

It will be interesting to see what works best.

I now own a SJ-16 and an AD-16, both with struts. There is very poor, almost absent oleo action when you push straight down on the model, compared to every other plane I own, no matter how hard you push. Only when you stand the bird up on one wheel about 45 deg, which obviously is not the usual touchdown configuration, do you get any oleo action, when finally the strut tube and force vector are in the same plane.

That is why, IMO, quite a few guys have torn the gear out of these planes. The AD is the worst, since the stock gear mount blocks are too soft, obechi blocks I think. I already have had to replace one of mine, and it's a major P.I.T.A getting it out and the new one in at the proper angle.

Nico at at least has a more substantial gear mount system in his 16, but with the big Air Magic retracts, big struts, etc., it adds allot of weight to the plane.

That is why the full scale 16 has the entire strut sprung from the point of attachment, so that the entire strut moves up and down.

Springing the gear from the point of attachment, and not with an oleo in the strut seems to have worked for the most taildraggers, and Cessna for ages, and actually is used on every high wing trainer with a 46 Max we all see every day at the flying field, with the gear coming off the fuse at a 45 or so angle.

I agree with the comments about soft tires to a degree. I think what Philip is shooting for is a compromise. Not too hard, not too soft. Large numbers of Warbird and Giant Scale guys, including myself have landed 35-40lb. planes with Robart tires, and mine never seemed to melt on the tarmac, but then, in between flights, I usually remove the plane from the scorching tarmac.

Matt's question is key, since I might be interested in starting with the scale gear, if it is available, since you have to use different arrangement of the bulkheads to get it in.

My kit is shipping next week, so at least I will have the real deal in my hand before making any decisions.

Anyone who saw Alan Cardash fly the big Boomerang at FJ 2003 with essentially flat tires, had to be impressed---not suggesting that I am ready to put these on my Bandit quite yet........

By saying that one has seen allot of AD, SJ 16 land O.K. just means you can land one wihout much spring action in the gear.

Tom

SpiderJets

Tomn,

The SJ-16 has the correct scale angle, which is 33%. The forces on these struts, no matter what manufacturer of the F-16 kit, are very substantial. For example, we also tried 4 mm wheel axles with the prototypes but quickly changed back to 1/4", although it looked to us completely overkill at the designing stage.
We have tried six different manufacturers of retract units as well and I can tell you that no other retract unit than the Air Magics will stand the loads in the long run. All others result in bended retract frames, due to the angle. We have flown many years ago with the (economical) Spring Airs in the (Byron) conversion kits, and everyone had to replace the main units several times. Eric Rantet at AD changed to Air Magic as well, when we started with the SpiderJets F-16. Excellent choice. Agree with the higher weight, but at least with the Air Magics you buy quality made for the job. As you know as an SJ-16 owner, we opted for all the best parts available on the market without compromise in order to make the kit cheaper.
Last remark, the damping effect of course only works when the plane rolls (since the tracking distance of the wheels changes).
Thank you for your good comments on my kit.

Best regards,
Nicolas.

Kevin Greene

My Feedback: (85)

Tom,

I agree that given the angles on this gear you won't have nearly the dampening that you would normally have if the struts were perpendicular to the runway----But, I would rather have some dampening than no dampening at all. Also, concerning the stock solid wire struts, I don't think that there will be that much spring effect given how short and thick the solid struts are. I believe that there is only a little over three inches of wire exposed between the upper and lower strut blocks. Not much there to spring!!!!You will see what I mean when you get your kit. This puts all of the dampening loads on the tires, which will not be much.

The axles are only 3/16" in diameter----Much too small in my opinion for a model this size.

True, there are large warbirds and giant scale guys using Robart wheels and tires with excellent results. However, these large models are using the larger wheels/tires intended for that application. These larger wheels have much thicker rubber than the smaller Robart wheels. Remember, we are talking about a 3.5 inch wheel/tire combo that Robart suggests for use in models that weigh much less than the anticipated weight of this F-16. (Models such as the TopFlite 65" wingspan P-51)

I can also see problems with the plastic bushings in the Robart wheels given the weight of the F-16. The braking system that Philip uses is a combination of a machined aluminum drum (that is screwed onto the Robart plastic wheel) and a BVM brake unit. It won't take very long, given the weight of this plane, for the plastic bushings to wear. This will allow the wheel to become sloppy on the axle. Due to the tight tolerances it won't take long for the BVM brake unit to rub on the machined drum. I just don't think that these plastic bushings will last in this application. Here is some more food for thought concerning the plastic bushings.....I know that the takeoff and landing speeds with this plane will be lower than many other jets. However, to make scale takeoffs requires some speed. Speed, a full load of fuel and the heavy takeoff weight----I just don't think that the plastic bushings are going to last.

Just my .02 Kevin

X-15

Kevin,
I have an F-16 main wheel with brake in front of me, and there is not one piece of plastic here. The bushings are made from brass or copper. The rest is machined from aluminum. They are a real piece of art.
My .02
Patrick

Kevin Greene

My Feedback: (85)

Patrick,

I have what Philip sent me in front of me and what I have is a set of $10 Robart wheels with plastic bushings. I also have the foam inserts. Whose wheel and brake do you have??? Look on Philip's web site and take a look at the pic of the F-16 with the parts layed out. I've got what you see in the pic.

Kevin

X-15

Kevin,

This is what I got from Philip. I also got the same wheels 2 years ago on my F-15.
I recently upgraded the rubber wheels to the new ones, they are much harder, and do not need the foam inserts. Fabulous.
I have to admit that I spent more than .02 cents.

Patrick

Kevin Greene

My Feedback: (85)

Patrick,

Those sure look good!!! I got the first kit in the country so maybe things have changed??? How do you feel about the wire struts? I have both the "scale" ones with the resin castings over them and the plain wire struts. I know that the ones with the resin castings will not spring at all. The setup that we are going to use is the Robart struts with the scale machined 3.5" F-16 wheels from Trim. I'm going to keep the stock wire struts as spares in case the Robarts get damaged. The only thing I need to do is to modify the lower block to accept a 1/4" axle.

Kevin

X-15

Kevin,
I bought my F-15 more than 3 years ago, including the same wheels.
I am gonna use the wire struts until I can buy the scale gear. I am afraid that the ones with resin casting will bend, just above or below the resin. The wire struts have already proven themselves. Philip and his son have flown them for a long time with good results.
Personally, I thinj=k the oleo struts will not work. A friend of mine tried this on a F-104, with serious consequences.

Patrick.
PS When did you buy your kit? I thought I was the first, almost a year ago !!!!

Kevin Greene

My Feedback: (85)

This kit was purchased from the original owner, Kevin Barr. I thought that this was the first one....Not that it really matters. Overall I really like the kit. Builds fast and well engineered. This plane should be really fun to fly. This one is going to be painted like the ones at Edwards----white with orange high vis panels. What scheme have you chosen for yours? I got out the Dremel and cut out all of the grills, scoops and gun port. I was worried that the areas where the grills are would be rather fragile after all of the material was removed so I laid two layers of ten thou carbon mat in these small areas before the grills were cut out. This stiffened up the grill areas considerably. I used a small flat jewelers file to shape up the grills after the rough cuts were made. I use real small drills that my dentist gave me for the initial rough cuts. These were used drills that were too dull for teeth---They sure do go through fiberglass still!!! If you get some drills and burrs from your dentist be sure to have him sterilize them in an autoclave first.

Kevin

A10FLYR

My Feedback: (1)

As Nico said, the damping effect only occurs when the plane is rolling. I helped this by toeing the wheels in about 1½° so that when you land a little hard the forces combine to push the strut up and therefore soften the landing.
I agree with Nico on the choice of retract units. I originally used the Robart 150 giant scale rotating units but a hard landing would bend the sheet aluminium frames. After switching to Air Magics I had to beef up the mounting area but had no more retract problems.

Tom Antlfinger

My Feedback: (24)

Kevin:

I think there was a change somewhere early in the kit runs, since all the photos in the RCJI article as well as the photos I got from Philip show the metal hubs. Unfortunately, I didn't save that last informative note I received from Philip, that included photos.

As far as the axles go, I have had misgivings about 3/16" axles, but since I have been flying my P-120 Bandit which dry is 21 lbs, and wet almost 25lbs, with no trouble even on grass, I am going to try these. BV uses 3/16th even on his big birds. Not sure if they are specially heat treated. I have had non-BV axles snap in the past. I think Ad Clarke is flying his Phantom with standard 3/16" axles on typical hard-as-rock BV tires off grass up in Kalispell. I am not absolutely certain, but I don't believe BV offers any 1/4" axle wheels even on the 100 or big Rafale.

After studying the RCJI photos, and with my experience with the AD-16, I definitely am going to double up the gear plate and adjacent bulkheads that the plate keys into with a 2mm CF plate sandwich. It is so much easier to do this during construction and weighs almost nothing. Just trying to emulate some of the stuff BV has done with the gear on his big birds. I saw a couple of nasty Phantom and F-100 hard landings at FJ, and was amazed how well the gear held up.

Philip's Kevlar tanks lateral to the gear should also help with the noseheavy condition associated with the AD and SJ on takeoff, due to their tank positions. This should be C.G. neutral, like with Gary Mueller's tank setup for the PA-15.

Anyway, getting real excited about getting it next week.

Tom

ghost_rider

My Feedback: (20)

FWIW, with more than 20 flights on my SJ F-16, I have not noticed any CG problems on takeoff. I carry one 58 oz in the nose (Gary M. tank) , 2 X 24 oz in the rear + 4 oz hopper tank in front.

Regards

Ben

Tom Antlfinger

My Feedback: (24)

Ben:

I have the similar system in my 16 (Ron Ballard's Bird)...56 front, and 48 rear with UAT up front.

You are right. I should have been more specific. The nose heavy takeoff problem is really with my AD, where all the fuel is well in front of the C.G. on takeoff. No problem on hard surface, but really pounds the nose gear on grass. It was built using CAI tanks, and the nose is glued on, so I have no choice but to stick with the system that is in it.

On the SJ, two things I don't like are:

--Carrying that rear 48 oz of fuel just inches lateral to the hottest portion of the pipe...probably not the safest thing if you crash with the motor still running.

--As the rear tanks drain, you eventually have all that fuel in the front tank, well in front of the C.G. Not a real big deal if you are still flying---just a few trim clicks to keep the nose from dropping, but if you have to land at that time, especially on grass, you pound the stink out of the nosegear. I did following F/O and tore the nose gear retract mount out........unable to flare at touchdown airspeed.

Nico's overall design is quite elegant, but I personally prefer all the fuel on the C.G. and using the generous nose area for retract valves, gear door valves, switches, etc.

I have thought about getting rid of most, if not all of the inboard fuel, and going to an external wet centerline tank. The bird is a wall hanging right now. I do plan on a major interior make-over next winter.

Tom

SpiderJets

Tom,

Beefing up retract gear plates is not the best solution.... In case of a dirty landing you will only transfer the shock to the next weak point... which can be the fuselage. In fact, the best solution is to make the gear plates removable so you can exchange these when broken. I've done this on two of my own planes and it takes very little to replace them ; only the extra homework when building the plane was what it took. The dimensions and thickness of the plates remain the same. For shows etc. I even had a spare set of complete leg units (L & R) with me which could be exchanged in a very few minutes.
With the SJ-16, having the heaviest part (being the turbine) on the C of G, it is impossible to have tanks there. I have never encountered any change of CG during flight, not even with the 100 oz fuel system. You only have to be careful (VERY careful) with the F-16's not to make them tail heavy. A correct CG makes a whole difference on the F-16. Mine flies and lands slower than any other jet.

If you wish, you can experiment with an external (belly) tank such as the wing tip tanks from Trim Aircraft. I purchased a set to make a smoke fuel tank, but never completed this. These tanks from TA are very light, do fit under this size F16, and are not expensive at all. You have to convert these yourself of course with a bit of imagination.

Last remark : as soon as the wire struts will be replaced by oleo struts, the retract units WILL suffer badly. Perhaps better to cover them with plastic or resin strut covers...

No bad word about the Robart main oleos, these are impossible to bend. Robart know what they make.


Best Regards,
Nicolas.

Tom Antlfinger

My Feedback: (24)

Hi Nico:

Thanks for the comments.

I actually have been giving thought to making them replaceable as BV does with his carbon fiber "Flex Plates" in his kits. Those of us who have Bandits know how well these do protect the retracts and the fuselage in the event of a hard landing.

The engineering is not that complicated, since you have those massive gear wells on the 16's, well exposed when the doors are open.

Tom

SpiderJets

Dear Tom,

Attached a photo of such gear plates. The right hand one is like they come with the kits (and has dents for our interlock build system), the left hand one was for the removable ones. These are bolted with four M4 bolts to the vertical formers F9 and F2, and can be replaced immediately when broken. Note that all internal woodwork is fully pre-assembled with the latest kits ; these gear plates are glued in place on purpose with wood glue so you can break these out easily if necessary (which would not be the case if assembled with epoxy glue).

Best Regards,
Nicolas.

SpiderJets

(Attached photo below)

Tom Antlfinger

My Feedback: (24)

Very nice Nico....

Tom

SpiderJets

Thanks !

Nicolas.

PS. If I could, I would devote all my time to designing and improving my kits continuously and nothing else (except flying). So, if someone wants to do all the production and sales... be my guest ! I have some superb ideas for a new kit but lack of time... as usual.