We have liftoff, the 2 Bits Bipe has flown

[John Miller]

This morning, I loaded it up in the van and headed up to Gordy's house. Carl Shoup was visiting, and both of them, Norm Whittle, and Jimmy Rhoades were going to be flying at the park near Gordy's house.

I had checked the balance at home, and it appeared to be about right without the need to add balancing weight. It also appeared to hang straight from the leadouts, making me believe that the vertical CG was at least close.

I put up 2 flights on the bipe. Talk about a bundle of nerves though. We had to hand launch due to the thick grass, and I was surprised at how nicely the plane handled a hand launch.

Level flight seemed good, no tendency to hunt was observed. it did seem to have the outboard wing low though. I had short tanked the plane so because of nerves, and not wanting to have the plane shut off somewhere I didn't want it to, I just did some climbs, a shallow wing over or three, high flight, and an inside loop.

The Stalker .61RE had good power, but a little more might be needed if I really try to nail a pattern. Lap times were 5.0 on a APC 12X6 prop.

The biggest surprise was when the power shut off. I expected the plane to drop like a rock, as I've seen other biplanes do. This one glides. it glides as good as some of the mono wings I've flown. I don't know yet, but suspect that there's a combination of weight, and clean design, that allows it to penetrate in the glide.

It didn't like the grass for landing though. It tried to roll over on the top wing, but didn't get that far, coming back to rest on the gear like a proper lady.

Carl offered a CF copy of the APC 13X7 electric prop to try for the second flight. It's a beautiful, well made CF copy, and the engine spooled it up as fast on the ground as the previous prop. In the air, the engine settled into a deeper 4 cycle, and the lap time dropped to 5.9. This was a bit slow, and I wasn't real sure the plane would perform at this altitude, (4,600 ft ASL) especially with the temp going up as it was.

The flight went about the same as the first, though I could feel the planes weight more, due to the slow flight, I did more climbs, high flight, shallow wing overs, and loops. Finally, I went inverted. Scared me as the plane rolled in slightly, and for a second, I had little or no line tension. The tension came back a bit, but the plane was flying with the outboard wing high. The engine seemed to have about the same sound-speed, so after only one lap, I did an outside to bring it around to upright.

All other events were about the same as the first flight, including the landing.

A third flight was attempted, but apparently something, possibly a bit of crud, made the engine balky and not wanting to start.

So, I'll remove the engine, and check out the fuel system. I'll also need to tweak the flap horn, as the inboard flap is slightly lower than the outboard, which is what caused the uneven wings and rolling upright to inverted.

My feelings at this time allow me to surmise that the plane has a lot of possibilities. It will fly and do round maneuvers on the current power, but an increase should make it much better, especially for the square maneuvers. I might be able to upgrade to the Stalker .66 rather than the .81. The .81 would have all the power needed and then some, but would require adding balancing weight, whereas the .66 essentially weighs the same as what's in there.

All in all, I'm pretty happy with it all so far.

Carl took several in-flight photos, and he'll be sending them to me after he gets home tonight.

[Bill Hummel]

Congrats, John, many of us have been awaiting the first flight report!

[Tim Wescott]

Yes to that!  Boy, oh boy, if you could get movies up with that.

Are you going to bring it to any upcoming Pacific NW meets?  Are you going to fly it at any of 'em?

[John Miller]

Next weekend should see us back at the park, with some adjustments. I plan on using it for the rest of this season, and into next, at the very least.

[PJ Rowland]

I would put the .66 in it..

Or get the .61 Longstroke - thats what I wsa running in the Gieseke Nobler at the Nats.

My gut tells me the .66 would be a better solution, the .61 prefer a plane under 58oz to perform properly.

[Air Ministry .]

Good glide indicates its efficent , so shoulp have the potential to work really well.

Stalker 76 has i/4 more hight , but same fit otherwise .
Dont like them trying to knock the bypass in with the ' 66 ' stamp .
Should leave the 61 on and stamp 66 on the edge of the lug ?
same dilema with G-15 / 19s . But thats just me being crankey .

When are we going to get some ' movies ' of the flights ?

[John Stiles]

Holey smokes, you had me sweating and really nervous......I have 2 bipes that have never been hooked up...those little deviations you mentioned made me feel like I was on the control handle with one of my bipes! Whew....and oh yeah, could you post a picture or two? Thanks for the report!

[John Miller]

Carl Shoup posted these pics on SSW. Thanks Carl

[john e. holliday]

At least it flies,  now you have something to work with.   Looking at the grass, it looks shorter than what I fly off of.  May need bigger wheels.   By the way, what do you think of Carl's electric prop?   I have heard he is not allowed to use it in competition at some places.  Also if it, the 2 Bits Bipe, could be down sized to a 46 LA.

[John Miller]

At least it flies,  now you have something to work with.   Looking at the grass, it looks shorter than what I fly off of.  May need bigger wheels.   By the way, what do you think of Carl's electric prop?   I have heard he is not allowed to use it in competition at some places.  Also if it, the 2 Bits Bipe, could be down sized to a 46 LA.

Yeah, the grass is nicely cut, but too thick, and too tall to make for good handleing. All the planes must be hand launched with only a couple of exceptions. The field is actually a soccer field and the grass is very tough, and thick. Bigger wheels might help.

Edit: I attached a couple of pictures taken on the ground, before the first flight, and after the last flight. You can see the black CF APC copy prop on the last picture. You can also see how tall, and thick the grass was, that made it necessary to hand launch.

Carls electric prop has been in diuscussions in the past. The one he had me try, is a Carbon Fiber copy of the APC 13 X 7, and is beautifully made. I don't believe there is a problem using this particular prop in competition, as it's as strong as about any other prop that might be used.

It, the 2 Bits Bipe,  actually seems to have a lot going for it. So far I know it tracks true, and does round manuevers pretty well. Even at it's porcene weight, it seemed to enter and exit the loops correctly. In the climb, it seemed to make the vetical line without too much of a problem, other than showing a possibillity of being happier with more authority in the nose.

I'm saving up to purchase a bigger engine, so that should be available in the future.

Making a smaller version should not be a problem. CAD files are easily scaled. I'm figuring 600 - 620 sq inches, and probably not take apart, but first, I need to finish up with the original, and modifications to finish it off.

Today, I will be taking it apart, and checking all the connections, as well as removing the engine to see why it was unwilling to start for a third flight yesterday.

[Norvaldo]

Hi John.
A comment on the engine part.
I seem to remember that you have the older version of the Stalker .61.
If you take a look at the weight chart (included) you will see that this engine is 352 grams (ex. muffler) or ca. 12.4 oz.
The newer .61 & .66 are ligther (ca 1 oz).
The .76 is 365 grams, very close to your .61 if my assumptions are right.
Norvald

[FLOYD CARTER]

The reason your glide is so good is the large separation between wings.  An efficient biplane would have the bottom wing as low as possible, and the top wing on a pylon, like yours.

Floyd

[John Miller]

Hi John.
A comment on the engine part.
I seem to remember that you have the older version of the Stalker .61.
If you take a look at the weight chart (included) you will see that this engine is 352 grams (ex. muffler) or ca. 12.4 oz.
The newer .61 & .66 are ligther (ca 1 oz).
The .76 is 365 grams, very close to your .61 if my assumptions are right.
Norvald

Thank you Norvald for this information. It makes the choice for power a bit broader for me.

As a side note, My sincere best wishes for you and your countrymen during this trying time.

[Bob Reeves]

Snip

Carls electric prop has been in diuscussions in the past. The one he had me try, is a Carbon Fiber copy of the APC 13 X 7, and is beautifully made. I don't believe there is a problem using this particular prop in competition, as it's as strong as about any other prop that might be used.

Snip

Is this a reverse rotation prop and can they be purchased?

[John Miller]

Is this a reverse rotation prop and can they be purchased?

No, it's normal rotation. I believe they are made in China, and are available on Ebay. Best to contact Carl about this prop.

[John Miller]

Thank you Floyd, for your comment. I believe that is the main reason it glides so well. I also believe that the weight allows for better penetration, which contributes some to the quality of the glide. One of my goals with this design was to come up with efficiencies that contribute to allowing this planform to perform well in our arena. Time will tell, but early results show promise.

[Bill Ambrose]

John,

It looks great in the air.  It sounds like with a few minor tweaks you'll really have a nice flying plane.  Glad to see it.  I have an R/C Ultimate bipe I like a lot.

Bill Ambrose

[Steve Helmick]

Hand launching seems really scary to me. I'd suggest carrying along at least one sheet of cheap panelling to set the model on to allow a start on the takeoff run.

Good to hear that it flew safely. Take your time. I'd still go for the .81!~  Steve

[Mark Scarborough]

Steve, yeah I can attest to the hand launch scarey thing. Pat hand launched my avenger in eugene while I was on a quest for a replacement prop for my second attmept,, talk about pucker factor. however, pat did it right and there really was not much drama. there is so much power and wing area, it really was a non issue,, well at least that time LOL

[Will Hinton]

My local r/c club doesn't mow the grass low enough to take off from, so I carry a sheet of 1/8" masonite I have cut into 4 even parts and lay those out for a "runway" for take off when I fly alone, which is almost always.  They fit in the back of the van with no problem and give me safe flights.  The landing thing, however, is much like John's!  I don't like those, but if I want to fly...

[John Cralley]

My local r/c club doesn't mow the grass low enough to take off from, so I carry a sheet of 1/8" masonite I have cut into 4 even parts and lay those out for a "runway" for take off when I fly alone, which is almost always.  They fit in the back of the van with no problem and give me safe flights.  The landing thing, however, is much like John's!  I don't like those, but if I want to fly...

I do the same thing and in my case I put a couple of coats of polyurethane on the boards to resist the heavy morning dew that I sometimes encounter.

[Air Ministry .]

Starting to sound like Carrier .Need a Catapult to Launch ! 

[Will Hinton]

Hey Matt - My PA65 and PA75 ARE catapults!  Actually, I have eight feet of "runway" and my Tutor II with a LA46 also gets off just fine.  Those landing, though...

[Air Ministry .]

Tail Hook & arrestor wires  ? .

Cant you take the lawn mower to clear a strip ?

[John Miller]

We took the Bipe out this past Sunday morning for more flights. I still am having problems getting the wings level, upright, and inverted. It was better than last week, so I did a couple of laps inverted. Other than the engine speeding up, because I need to adjust the uniflow, it was uneventful. It seemed to groove well, and had no tendency to hunt, either upright or inverted.

Inside loops were fine, and easy to make round, but because of the wing situation, I opted out of outside loops, other than the half loop used to return to upright flight. These were bigger loops, but I believe I did it because of the planes attitude, (Banked in towards me) not giving me a huge amount of confidence.

After the engine quit, I once again enjoyed the glide, going well over a lap after the power was off. Upon landing,  the plane nosed over in the tall thick grass, and a sharp crack was heard by all. I looked the plane over, and all seemed OK, so it went up for another flight after I had tweaked the flaps to try and get the wings level.

Most notable on this flight was that I had tweaked the flaps too far, and the plane now flew upright banked into the circle. I did try a square loop though. First turn was good, and it hit the vertical line rather well, it hit the inverted line well, as well as the downward vertical line. The last turn was slightly sluggish, and it didn't turn at the same speed, so I came out slightly nose down, and had to make a correction to level the plan. To those watching, it looked like the plane might have stalled on the last corner, but it was showing it's weight in the last turn, but wasn't stalled.

Again, the glide after the engine quit, and another nose over on landing.

I was getting ready for a third flight, taking some of the tweak out of the flaps, when I looked at the gear leg. Then I knew what had made that loud cracking sound on the first landing. The Ply-CF hybrid gear had twisted, and one of the laminations had let go. The gear had bent back far enough afterr that, that the rear of the wheel pant dented the lower wing sheeting. I was done for the day.

So, I'm making up a new gear, and plan on testing it well, before deciding whether I'll go to standard CF gear. I've also been looking over the controls, I believe  I may take the time to re-center the flaps and elevators, as right now, the flaps are slightly down, when the elevators are level.

I hope I can make all the needed adjustments and fixes so I can take it out again next weekend.

I will say, it looks great out on the end of the lines.

[EddyR]

John
   I have built several bipe's over the years. None were full stunt planes but they all could do loops and lazy eights. Even my scale Great Lakes will do lazy eights. One thing they all needed was  A LOT OF WING TIP WEIGHT. Maybe 2 ounces.
Ed

[Tom Niebuhr]

John,
With the tip overs on landing, while you are making a new LG, you might also consider having a dual set of mounting holes in the gear so that you can place the gear further forward for grass. That is probably one reason so many OTS airplanes had gears further forward than we normally use today. Those OTS airplanes weren't always good on pavement, but they landed easily on grass.

[John Miller]

Good point Tom, thanks.

[PerttiMe]

I still am having problems getting the wings level, upright, and inverted.

No warps anywhere? Unfortunately, a second wing means more things that need to be set up just right.

[John Miller]

Due to the problems with the home made ply-CF gear de-laminating on several landings, I've been unable to put up more than 4 flights total. It was obvious that I needed to address the problem before going much further. I believe the problem comes from trying to use regular hobby type 30 minute epoxy, which just doesn't seem strong enough to work in this instance. It might work better if I'd used a professional grade laminating epoxy, but none was available to me at the time. This was brought home to me when the new set of gear I made failed when I tested it, knowing, from experience now, what kind of stress was occurring.

So, I decided to install a set of commercial CF gear. It took some searching, but I finally found a company that supplied gear that was almost a perfect match for my needs, just being a little bit taller, which won't hurt at all, what with the tall grass I have to try and fly off, and onto.

Since I was waiting for the gear to arrive, I took the plane over to Gordy's, and we put the gauges and meters to it. I suspected that some alignment may be off. The meters showed that the flaps on the lower wing were aligned with the elevator, both showing 0-0 at neutral, but the top wing was off, showing a 5 degree droop when the lower wing is at 0-0. After making adjustments, every thing is within a fraction of a degree to each other.

The new gear is installed, so I checked the vertical CG in case the differences in weights may have moved it. I hung the plane from the leadouts and set a torpedo level on the fuselage flat spot between the wings. It appears that I will have to move the leadouts down about 1/2". Turning the level 90 degrees shows the nose hanging slightly down, which agrees with  my assessment regarding line tension on my last flights.

Now, with the new gear, which should allow a lot more flights during a session, I should be able to quickly get the wings level, and adjust the uniflow for equal lap times upright and inverted. After that I should be soon flying the pattern.

[John Miller]

It's been a couple of weeks since the last flights on this airframe, mostly due to poor weather problems on the weekends.

Today, we met at the field, and put up some more trimming flights.

I'm still working on getting the wings level, but they are pretty close now. I was suprized to find that I needed to raise the leadouts. I referenced to the wings this time rather than the fuse sides.

Today I did some consecutive loops. They were nice and round, with entry, and exits at the same altitude. They tracked true which makes doing them much easier.

Level flight was good, and also tracked true, upright, and inverted.

Then, I tried some inside squares. This is where the extra weight showed up. Turns 1,2,and 3, were good, with a nice and sharp snap to the verticle or horizontal lines, until the last, number 4 turn. That last turn showed a stall, unless I eased up on the turn. Even eased up, it still showed a tendency to stall.

So, here's the cure we came up with.

I want to try and get rid of some weight, and add some area, to get a better wing loading. Here's where I'm glad I can easily remove and replace parts.

I believe I can get rid of several ounces by building a new top wing as a one piece structure. That's half of the solution, the rest is to increase the chord slightly, and add some span to that top wing, to increase the area.

I figure to have the new wing ready soon.

Now, my impression is that if I can keep the first 3 turns in a square manuever, and match those with the last turn, this just may wind up being a very nice stunter.

Stay tuned

[wwwarbird]

So, here's the cure we came up with.

I want to try and get rid of some weight, and add some area, to get a better wing loading. Here's where I'm glad I can easily remove and replace parts.

I believe I can get rid of several ounces by building a new top wing as a one piece structure. That's half of the solution, the rest is to increase the chord slightly, and add some span to that top wing, to increase the area.

I figure to have the new wing ready soon.

Now, my impression is that if I can keep the first 3 turns in a square manuever, and match those with the last turn, this just may wind up being a very nice stunter.

Stay tuned

 Sounds like a reasonable plan John, but I think the downward stall/turn issue might just be a "Biplane Thing".

[John Miller]

It's been a learning thing for me. The trimming has been a challenge, until I took the time to really think about it. The problem with getting the wings level has multiple elements affecting, and wotking against each other.

I finally realized that with the adjustable leadouts, which are not only adjustable fore and aft, but also up and down, that I was chasing my tail unless I first got them adjusted vertically. This meant, as I finally figured out, that I needed to adjust the leadouts in the vertical plane, until the plane's attitude was the same upright, and inverted. In this case, I wound up with the plane banked in at the same angle, upright and inverted. Now, it was simply adding tip weight until the wings were level.

When I built the wings, I added 1/2 oz's, permanently mounted in each wings outboard tip. I figured to add any needed additional weight to the outboard strut, in line with the leadouts, to avoid altering the vertical CG.

Yeah, it sounds simple now, but it was nerve racking getting there.

Anyway, it now flies with the wings level, and if I don't honk on the last sq. turn does a reasonable corner. The corner should become much better with the new wings I'm building for the plane. I'll be increasing the wing area just short of 100 additional sq. inches. I also feel that I can lose 3-6 Oz's with the new wings, which won't hurt at all.

Since I last posted, I've removed the Stalker .61RE, and added a Stalker .81RE. I'm running a 14 X 6 classic Top FLight prop, but I may need a bit more pitch. I'm launching at 7800 RPM, and lap times are around 5.6-7 seconds. I've a different prop to try next outing, one of those Eastern Block wood scimitar blade style props, that really looks promising. The pitch gauge shows 5.9 mid blade, but it's going up as you move out towards the tip. An inch from the tip, it measured 6.75.

I'm going to try and get a 14 X 7 prop to try if I feel I need more pitch.

At the 7800 RPM, the big Stalker has a sweet run, breaking in all the right places, and I'd like to keep that.

I tried a 15 X 6 Scimitar wood prop of the same manufacture, but it loaded the engine to the point that it didn't want to run with a break.

Now, I find that with the bigger engine, I'm now nose heavy, to the point that it takes a bit to turn the plane, the loops want to open up as the consecutives are flown. The power off glide is not as good. I hate to have to add more weight, but it's going to be necessary.

I might, eventually, be able to mount the top wing a bit further forward which will move the balance point in the right direction without adding weight.

I'm certainly happy that the design allows for so many different optins with mounting wings and such.

I'll post more after a few more flights.

[PJ Rowland]

Great to hear the Stalker .81 worked for you.

Remember I usually ran 12.5 x 8 1/4 " Props