BVM F 16 (original)
 

About 20 years ago I built an original BVM F 16, did the turbine conversion but never flew it.

Its been sat in my workshop ever since, other projects overtook it.

I am thinking of installing my Xicoy X 45, a truly superb engine, which would actually give a better t/w ratio ( the X45 installation would very light) than my JPX T 33 combination of 20 years ago.

Anyone with experience of this jet, fan or turbine care to comment?

Hello David,

I had one about twelve plus years ago. I didn’t build it, but bought it off of a guy at the field having financial issues. It was my first turbine with an air start Mamba. In the video I’m still learning to start it. Truly a pain in the butt. There’s a guy in the beginning with a good Southern drawl that says, “sounds like the front wheel is stuck”. Cracks me up. The jet weighed about 22# with an 11# thrust engine. So very heavy wing loading. I had been flying a BVM DF Maverick with BVM.91 and.96, so wasn’t my first jet, just first turbine. As you are aware, the F16 can fly slower than it can land. The video is like my fifth or sixth flight. I didn’t have anyone to help me with jets. So I learned by the road of hard knocks. Because I wasn’t used to flying turbines, I got behind the power curve as soon as the nose came up to expose the gear door (drag brakes). I about lost it on the first approach. Had I not put the gear up, I would have lost it. The final approach, my knees were knocking and knew that I was low on fuel and had to land. Still got behind the power curve.

You Tube

Good luck with the X45. A buddy here on the field has one that has been back to be fixed twice with less than five hours. He had two flame outs. This last time, it quit on the USA Reps bench. Seems to be the same issues as Jetsmunt, since the same guy is running it. Just name change. Maybe I am wrong?

Hi Dan,
My sincere thanks for your reply, just what I needed.

Dont know what happened to the Mamba, I ordered one when show it at Florida Jets many years ago, then nothing, it just disappeared.

Having seen yours fly on the excellent video I think the 45 will be fine at 10 pounds as my F16 is quite light, Humbrol paints which weigh nothing.

So, if the gear still works after a pressure check I will press on. I have all the underwing tanks etc. Shame to waste them.

I was warned, years ago, about the high drag with the gear doors open so I will be ready and the x45 has rapid throttle response !

I have only a few flights on the 45 before its midair in the L39, but like my JetsMunt 100 , 50 flights in my BobCat XL , it has been perfect.

All that said, in another corner of my workshop was an Avonds F15 waiting for repair ( shot down on 36 Mhz, flying through a microwave link in Australia).

So, it crosses my mind that the F15 ( which flies beautifully) with TWIN 45 s might be fun.

With all my 12 jets serviceable and my two Covid projects almost done (an Airworld Sea Fury with a Moki 250 and a Balsa USA 1/3 Cub, with an OS Pegasus) seems the F15 and F16 will go ahead !

Again, Dan, many thanks for you reply, THIS is RCU at its best.

David.

Oops, double button press

My Pleasure! It’s fun to go back down memory lane. I started laughing at the engine popping. It was new and He never flew it, but he had the engine from previous jet. He never flew jets at our field, so I had never seen one start, or him flying any other jet. All I knew was there was open propane, jet fuel and a flame. After I paid for it, he demonstrated a start for me. We weren’t going to fly it, because of too tight of field and short runway. So just a demo. I was knelt down on the opposite side of the jet then him. He opened the air to the scuba tank, started adding air to turn the turbine, and proceeded to open the propane valve. Well it popped! And I ran! I thought the whole thing was going to blow up. Of course he got a laugh. The gear are stout, and strong, as you seen. So very worth while finding O-rings. The engine was in a full bypass. You saw that I only had one throttle setting at that time! Full! I’m in Florida, so that day was probably at least 85 degrees and a 500’ runway. I use soft field technique and hold about half elevator from takeoff roll and let it lift off when it’s ready.

I hear you in cooped up! I have two jets ready for their maiden. Working on the the third.

I have a similar project. A very early Yellow Aircraft F-16 kit, a HSD F-16 landing gear and a X45 turbine which should arrive on wednesday. I am thinking of putting the X45 into the tail of the F-16, so I do not need a thrust tube. Anyone has experience with that, or does not recommend it for CG issues?

Regards,
Chris

I have an original kit to build.. Plan is for either EDF or a KingTech K70G4. I've flown a few old glow DF versions and the airplane flies very nicely, but keeping the weight down is a big focus.

Thanks for your replies guys, very much appreciated, I will give it a go and use the x45 , particularly in keeping with Doug,s suggestions of keeping it light.The 45 is extremely light and will require only 1 litre of fuel, so should be lighter than a DF.
I will use my PB Core with 9 ch receiver and an I Gyro sat, after seeing that very high angle landing I will use attitude hold on pitch as well as roll.
Sorry, Christof , Im afraid I know nothing about the Yellow F16 but I know you will be delighted with your 45 and very surprised to hear of the flameouts mentioned by Dan.

Apart from my main Covid projects the Sea Fury and Cub, at least CV has given me time to dig out the F16 and start to repair my damaged Avons F15.
.... but first, this afternoon, the first engine runs of my new Moki 250 in the Sea Fury ( best birthday present my wife ever gave me !)I know they sound glorious.

Slight jet connection, a Sea Fury shot down a Mig in Korea !

Thsnks again for your replies, guys .

David.

I have a friend's "baby" F-16 in the shop right now we're trying to get flown, should happen in the next couple of weeks. Haven't put it on the scales yet - I don't feel like there is any way it's in the 20+ lb range, but now I'm curious. I'll try to weigh it tonight. We have a JetsMunt 70 in it for power. Original owner used an old P-80.

I have been having fits with the gear, the airplane came with a box of what must have 12 or 15 bent main gear struts, and I had to get one more - BVM no longer supports the gear but luckily they were able to scrape their parts bin and find me one. I thought about looking into converting some other gear (Chris above mentions HSD, I was thinking that one or the T-One gear) but hopefully won't be needed.

Hello David!


Do I remember that you are also a retired 757 Capt? Or is that the other David in England? I try to replicate full scale, and if you think about it, full scale comes down the glide slope with 5 degrees nose up. So I try to replicate the approach.

The approach in the video was very poor and I was lucky that I didn’t loose it. I wasn’t flying a gyro back then, and you saw how stable it was at the high alpha. That was 12+ years ago and I was still learning, and since then, I have flown other F16’s, F18’s with the HSD F16 being one of the more challenging. I’ve learned that the secret of a perfect landing is the approach set up. Now, I trim the all jets for landing in the same way. Flying the race track pattern at half throttle, gear and flaps down, I trim for level flight. On the maiden, if your radio will do it, I use one of the knobs set up at 10% to trim the elevator with flaps down. Then add or subtract the percentage from what I have roughly setup in the flaps-elevator mix. Then delete the knob settings. With the F16, F18, 104, F4, etc, this will give a 5 degrees nose up attitude in level flight. For the F16, I’ve flown it in three different set ups. Everyone of the setup is using 20 degrees flaps. More flaps blank out the stab and makes for control of flight issues. The 20 degrees helps the attitude to keep the nose down.
Setting 1.) Stabilizers set as normal elevator. Ailerons are Flaperons at 20 degrees. 2.) Stabilizers are set to stabilators, and ailerons are still used as flaperons, so everything is moving. 3.) Ailerons are set to flaps at 20 degrees, ailerons are locked out. This is so flaps stay as flaps. And stabilzers becomes stabilators or tailerons increasing the left and right aileron movement. High speed flight, they don’t need to use much, as we all know.

I prefer #3. With 1 & 2, the ailerons are still able to work as ailerons. With the jet at 5 degrees nose up, it’s on speed. You are controlling the decent with power. Downwind to Base, maintaining the 5 degrees nose up, I reduce power about an 1/8 of a stick maybe a little more to a 1/3 throttle. This starts the decent, just as full scale. I then control the decent rate with throttle maintaining the 5 degrees nose up and pretty much hold 1/4 to 1/3 throttle until 2-5 feet off of the ground. Do not reduce power before then or you will end up short. The gear doors are huge speed/drag brakes!!! You do not hold off! Just hold the attitude and maybe increase to 7-10 degrees nose up and let it settle. If you hold it off, you get the landing that I had hitting the tail and fins slamming down the nose. This technique works for all of the high performance swept wing jets. The biggest thing that I don’t like about setup 1 & 2, is when the flaperons are moving, the down wing flaperon dumps the lift in turns. The outside, up wing flaperon doesn’t move. This results in the drastic sink rate when turning base to final. Unless you are prepared to bring power in for the turn, and reduce again to maintain the decent rate. Remember on a turbulent day, the ailerons are constantly moving and constantly dumping lift left and right.
I prefer set up 3 where the ailerons becomes flaps and ailerons are locked out. Tailerons then control roll rate and elevator as stabilators. This allows for a more stabilized base to final and doesn’t dump the lift.
If you have to go around, if you leave the gear and flaps down, you know that the jet is trim for level flight at 1/2 throttle. I usually leave them down going around at full power. Once to pattern altitude, I reduce my power back to 1/2 throttle and the jet is stabilized again.

Auburn2, I believe that my weight was wet. I just remember that it was double the thrust. The gear were awesome and the wheels made it track extremely true.

Right now, one of my C19 projects is refurbishing a SM 1/5 F16.

https://cimg9.ibsrv.net/gimg/www.rcu...5a59db006.jpeg
https://cimg3.ibsrv.net/gimg/www.rcu...980b0336c.jpeg

Stay Safe! Stay Well! Dan

David,

Here is about the flame outs on post 116. My buddy is another David. His RCU s/n is: DRW302. If you want to chat with him. Fenderbean is the USA rep.

https://www.rcuniverse.com/forum/rc-...x45-k45-5.html

Hello David,

I think the BVM F-16/Xicoy X45 will be a great combination. I first flew my BVM F-16 back in around 2001/2002 with a BVM91R and a Viojett fan.

The thrust from this combination was good at the time but would be considered marginal by todays standards. From recollection my ducted fan 16 was 14.75 lbs dry. It needed takeoff flaperon to ROG from grass..However once airborne performance improved. I suggest flying with missile rails to aid visibility. Landings were straight forward, similar to an F-15, simply get the nose up and land with some power on. Sure the doors create some drag, but were not an issue. The biggest issues I saw with others flying this aircraft, were trying to land it at higher speed like an aircraft with a conventional wing. If you do fly off grass, ensure that the grass is smooth, as with the closely coupled main and nose gear legs/narrow track, the aircraft can get out of shape quickly. The aircraft never dropped a wing - I guess the scale washout and low aspect ratio wing helps! No point telling you this considering you flew the full size Concorde!

I'll watch in interest to see how you find the conversion once complete - I still have another BVM F-16 that I built to primer stage, then I stopped working on the aircraft 20 years ago...The best turbine choice then was a PST600, however my experience at the time using this powerplant in other jets would indicate that although the aircraft could be successfully flown with this unit, it would have had a high wing loading - X45 is a much better choice, I guess that's what 20 years of development can do!

Cheers, Frank

I have some stick time on the old BVM F16 and the most important thing is to keep it light!! She is a good flyer but after 16 pounds she gets harder to fly with each pound making it much harder. The ones I flew where EDF so they landed heavy also.

Should do good with the 45 size engine.

That makes sense. This one is right at 18lbs with a full UAT, holds 44 ounces of fuel so should be around 20.5lbs wet.

For what it’s worth the FS approaches at 11 deg aoa on a 2.5 deg wire (or 8.5 deg nose high)
https://cimg0.ibsrv.net/gimg/www.rcu...14b5e5d57.jpeg

Zipper suited sun god!!!! Of course someone uses SPF1000 regularly ;-)

Who else you going to get to signal airplanes merely by taking their shirt off if stranded on a desert island?

Thanks again for all the info. I guess the F16 is really a delta with a tailplane so can fly at relatively high pitch attitude, rather like my BVM F 4 which does not really stall just starts to sink rapidly, typical delta.

That said on “normal” wings I never allow the nose to come up above level and generally try to the approach slightly nose down to keep well clear of the stall.

Anyway I will press on with the F16 which should be extremely light with the 45, simple tanks ( I pinched the original BVM ones for a jet glider) and a lightweight single wall jet pipe.

Dan: Yes I am the David who retired as a 75/76 captain, we were dual rated. Spent my whole career flying jets. Started jet models in 1955 with Jetex !
Frank, : I. Never qualified as a Concorde pilot, my assigned course, # 8, in 1978 was cancelled just before it started. ( BA was losing money heavily then and was expecting Concorde to be grounded) However, I did maybe 200 flights on the flight deck giving the technical commentary to our charter passengers,

Again, guys, thank you for your help and suggestions, I will go ahead when the F15 repairs are finished.

David.

nice work!

Well, its almost finished and engine runs were perfect.

The jet now weighs just under 6 kilos, 13 pounds, with two 1000 rx batteries and one 2000 for the engine, a full UAT and one half full main tank.

With 10 pounds of thrust the T/W ratio looks more than reasonable !

The BVM bypass seems fine, very cool running, no fuselage heating,

Just need a smooth runway post CV for test flying, we shall see !

Hi David, i built two of them when they were released (one for a friend and one to keep) . I remember feeling sick when I opened the boxes and spread out the parts. So many of them! here is a picture in Museum of flight - scale competition in 1992-93. I flew it with a BVM .91 engine and BVM fan. It was okay but heavier than what you will have. It flies good just make sure of no "very Tight" turns on approach for landing (nope i didn't crash it!) Good luck and let us know how it went.

Behzad
https://cimg1.ibsrv.net/gimg/www.rcu...9ea58e899c.jpg

Thank you for your good wishes. Gotta bite the bullet !

Weight will be a little higher than I said, earlier, not much, but needs a little nose weight to correct C of G.

It may be a little more sluggish on take off compared with the fan version but my impression of the X45 is that it has a very high exhaust velocity, so thrust decay with speed will be less, so top speed should be higher.

Finally, anyone know the exact control surface travels. Cant find them on any drawings ?

Look here:

CG & Throws

Thank you !
Its interesting to see the C of G on that chart is 1/2 inch further forward than on the plans.

Just off to rebalance it and recheck all those throws !

Thank you again .

David.

Just added a slightly larger Ecu Battery, 2200 Mah, and an extra air tank ( now get 3 gear cycles) and. c of g is perfect.
Engine runs now perfect, everything VERY cool.
A couple of flameouts on the x 45 on rapid throttle closing cured by setting decel. to COLD.

Will add missile rails to aid vis, but ready to go !

PS ZFW but with full UAT exactly 6 kilos 13.2 pounds !