RE: Regal Eagle - A Journey
 

Yep, Edwin...I really feel like we've got her where she needs to be...a couple day's work, and I think we're ready.

RE: Regal Eagle - A Journey
 

That was a phenomenal story!! It definitely sounds like your next attempt will be the one. I am closely watching this thread as my TGA F-15 sits at the ready for the Cleveland, Oh weather to cooperate. Bob sure did design one heck of an RC airframe, that is largely the reason I decided on it as my D/F trainer.

I will anxiously be awaiting news of your next outing. I agree with you on the early damage issue. One of my favorite planes ever was a 40 sized Muchler's Cessna. On it's first flight attempt I veered off the runway and hit the safety fence breaking the leading edge of one wing. It was a painted wing so I pulled the dent out, CA'd the ends and put strapping tape over it. I proceeded to fly it that day along with about a bazillion other flights. It flew so well I didn't want to fix it and take away the good luck.


One day mine will fly!

RE: Regal Eagle - A Journey
 

Gboulton

Hmmm. My post did not. Well, you are not doing a repair. You are "retrimming the aircraft".

I remember seeing in another post another builder who had a similar problem. Bob recommended the same thing and it was solved. I think the plane involved was the big Delta wing bomber BP used to sell. On Bob's videos you see on flying off grass with very short takeoff roll. I was struck by the nose high attitude when I saw it. But the grass was LONG. It did takeoff with lots of authority! I think you have it figured out.

bob branch

RE: Regal Eagle - A Journey
 

Your story is typical of DF F-15s. One of the trickes we used to do was get her up full song on the ground, back off the throttle as you did, It will jump in the air. ( as yours did) and quickly get back on the power and fly away. As I see it you probably should have stayed on the power the second time.

Anoyher thing,check your nose gear and see if under power if it bends back. If so that will give enough negitive incidence to leep your SKATEBOARD on the ground. Grass will do this to your nose gear every time.

Glue the gear back in and try mu method, I bet it'll go fer ya!

Good luck.

RE: Regal Eagle - A Journey
 

Terry

Do you have less problems with that sort of things if you use a robostrut on the nose gear?

bob branch

RE: Regal Eagle - A Journey
 

Yes, excellent job telling the story of the day's events. Now waiting for the post that says she flew liek a bat outta hell!

RE: Regal Eagle - A Journey
 

Yes, but sometimes on rough grass the robostrut will bend back also. At least the Wire strut can be bent back. Use at least a 3/16 wire, it won't bend back as much. might make the difference between a SKATEBOARD and an homesick angel

Remember, Bob Parkinson is right you need at least 1.5 degrees of POSITIVE incidence at ROTATION!

RE: Regal Eagle - A Journey
 

Not sure if these will fit the retracts you guys are using but Central Hobbies sells titanium 3/16" struts, just cut to length (wear a respirator mask, use eye protection)

[link=http://www.centralhobbies.com/miscellaneous/titstruts.html]Titanium struts[/link]

They are much lighter and don't bend as easily. They CAN be bent but the bend doesn't usually set like the steel struts.

Edit: Well, the word filter here on RCU blocks it since its the first three letters for titanium. Just go to centralhobbies.com and do a search on Titanium

RE: Regal Eagle - A Journey
 

Just a brief update...

Got the nose retract back in, and the damage to the nose fuse repaired. The left main retract mount is also repaired. That seemed to be all the "damage" done. Once everything sets and curse, I'll reinstall the gear themselves, and get to work setting the correct incidence angle. That SHOULD solve our problems. Given no chnge in the weather forecast, I expect to fly her tomorrow.

One other note...since I had to dig in to the nose ANYway, I've added an extension, and moved the battery all the way up into the very tip of the nose...this should SIGNIFICANTLY reduce (or perhaps even eliminate) the 10 pz f weight I'd added into the radio compartment for CG balancing, which will, of course, cut down on the overall weight of the airplane. My HOPE is to get her down to 13 or less...gonna be close. I'll let y'all know how it comes out when all is said and done.

RE: Regal Eagle - A Journey
 

Well, that's pretty stunning.

Lost 8.5 oz of weight up front by moving the battery, and the remaining 1.5 oz of balance weight to the very front of the nose. :)

.7 lbs is 11.2 oz, so I probably didn't QUITE get down to my target of 13...but it's gonna be REAL close.

RE: Regal Eagle - A Journey
 

Still using the wire nose strut?

RE: Regal Eagle - A Journey
 

Yes, Terry...the one supplied by B&D w/ the retracts.

RE: Regal Eagle - A Journey
 

Well, sadly, the maiden flight report is also a crash report.

Took her out today, and was pretty jazzed about flying her...really felt like we had the problems sorted out.

Takeoff roll was uneventful...the aircraft rotated off the pavement in about 200', and looked like she had no problems doing so...definitely was flying slower than I expected, or liked, though...

However, Bob's design proved itself as, despite her flying quite slowly, she held on, and didn't show any signs of anything unusual...sure enough, as expected, she seemed balanced and, as expected, just a TAD tail heavy with the gear down, the CG having been set gear up.

Wasn't overly happy with the high AOA (due, obviously, to the slow speed) but was getting over the immediate jitters, and the plane banked right as commanded, and begin to climb into the pattern. I wasn't HAPPY with the performance, but it was "acceptable" for now.

About the top of the climbing right turn (at what was its fastest airspeed thus far) the plane pitched slightly nose up (I think that MAY have been me dumb thumbing just a bit) and rolled VIOLENTLY left. My immediate thought was, of course, that I'd tip stalled her, so I fed nose down and right aileron.

The plane stopped rolling, made a hard left turn, nose came down, and I THOUGHT she came back into my control, heading essentially 180 degrees from the takeoff roll. At this point, I heard the motor changing speeds, and KNEW I hadn't commanded that. The plane then pitched nose up again, rather notably this time, dropped the OTHER wing and, I believe, had completely stopped responding to any commands. She corkscrewed in pretty violently.

=================================================

A few considerations:

I've flown a fair number of aircraft, and while I don't THINK i lost it, it's certainly possible. A couple of behaviours just don't seem like ANYTHING an aircraft would do in a stall situation. (The nose up, the rolls to opposite sides, and most notably the uncommanded throttle changes).

When I moved the battery this weekend, I had the battery lead under considerable tension, to ensure that it did not dangle into the nose gear. Stupidly, I secured the extension connections with electrical tape only. The battery was IN FRONT OF the weight in the nose, yet when we arrived at the crash site (with the engine still running might I add, idling happily away) the battery was completely disconnected, and seperated from the aircraft...yet the weight was still in the nose in its original location. The electrical tape was all left on the extension, with the battery connector being completely clean.

My HUNCH is that my failure to take the proper precautuons securing the battery connections, and the high tension on the wire, meant the battery started pulling loose, and connection was intermittent, and then gone.

We HAD done an antenna down range check out to 50+ feet with engine off and engine running through its throttle range, with no issues, and I'd done one previously this weekend (engine off) out to 150' with antenna down...again, no issues. So i doubt it was a receiver or radio glitch.

Obviously, as I said above, it's certainly POSSIBLE that I simply stalled it, and got behind the recovery, being inexperienced with DF aircraft. The intermittent throttle and 2 sudden nose up situations strike me as "unusual", but not unexplainable. The throttle issue could well have been either A) I WAS maniuplating throttle, and just don't know it...certainly, old prop habits could creep up, and me not even realize it B) The aircraft could have, because of a high AOA (and thus changes in the airflow through the engine area) simply been coming on and back off the pipe. Secondarily, with this aircraft, the fuse itself is a signifcant part of the lifting surface of the aircraft...I can at least envision the concept of the FUSE stalling and somehow that resulting in a pitch up...though, honestly, the aerodynamics behind such a possibility would have to be researched further.

====================================

Some thoughts

There's no question that this aircraft was heavier than it really should have been to fly well. I WAS able to get it down to just a hair over 13 lbs, but it really ought to fly at 12 or less, in my opinion. Clearly, with BP's design, the aircraft can be built considerably lighter than it was.

I was right in an earlier post...DESPITE today's failure, it really has been worth it. The things I've learned about building, DF's, etc, have been invaluable, and only encourage me to try again.

As it is, absolutely nothing of any real value was damaged, save for the two main retracts. The engine and fan are fine, the thrust tube came through unscathed (a happy ancillary benefit o making it from fiberglass, I think) All the servos are fine (already tested each), and even most of the linkage survived. The battery and RX seem ok in a brief check here at the house, though obviously I'll want to cycle the battery several times and have the RX checked out before trusting either in another plane. Most o the molded plastic pieces included with the kit survived as well, with only a canopy and one o the wing lexes needing to be replaced.

And, certainly, I still have plans and templates and what not...since the plane was, essentially, a scratch build, I am, with just a couple of minor inexpensive exceptions, starting over from exactly the same point I started at originally....except I have the benefit of a significant amount of experience and knowledge I didn't have 6 months ago.

================

Going forward

There's absolutely no question I'll build another one. Probably 90+ percent of the cost is in items that have survived the crash fine. So, financially, it's a no brainer. And, of course, emotionally, I very much want an F-15 in the air. :)

I WILL make several changes, however. Among other things, I'll go with built up wings. While Bob's foam cores w/ jet skins are certainly strong, I think built up wings will recognize a significant weight savings. I'll also competely rethink the way I handled the engine, going with a remote needle valve, and possibly revisiting the in-flight mixture control issue. I'll also visit the idea of building a fiberglass nose assembly, again with an eye toward saving some weight.

Finally, I'll at least consider the idea of converting to a pusher fan. My own misunderstanding led to the selection of a tractor fan, but further learning and knowledge has made me believe a pusher fan would be more suited to what I want out of the aircraft.

I am, however, going to take a break from her for a bit. I've been just about obessed with this plane for several months, and realized the other day that I haven't just gone and had fun flying in quite a while. There's a 25% Yak at the LHS that has my name on it. :)

======================

In closing...

I can not say enough good things about all of you involved in this thread. Each of you have taken time out of your own lives and projects, and offered advice, and encouragement, and just generally made this whole experience more enjoyable. Thanks to each of you, and to those building their own Eagle, I wish you nothing but the best of luck, and hope to hear about your success! :)

RE: Regal Eagle - A Journey
 

Sorry to hear of your misfortune............................Don't give up, as you said all the expensive stuff survived. I would stick with the Foam wings. Built up wings have their own set of headaches. Plus a lot more work, as each rib will be different.

RE: Regal Eagle - A Journey
 

I am terribly sorry to hear about your misfortune. That will make it even better when the new one takes to the skies.

RE: Regal Eagle - A Journey
 

Thanks, guys. Appreciate the kind thoughts.

I'm not, to be honest, all that torn up about it. The crash does not change the fact that I had a blast building it, and learned tons that will serve me well for years to come. And, honestly, having built one now, I can see the second going together MUCH more quickly...I doubt I'll match BP's ability to build one in a WEEKEND, but a couple months doesn't seem outrageous. ;)

I do, however, think I'm going to take a break for a while from it, and get the big Yak up and going. :) Time to do more FLYING and less BUILDING now that the weather is so nice. :)

================

One last note...I've watched the video probably 100 times now...not so much obsessing over the plane's loss, but in an effort to learn EVERYTHING I can from it, so as not to duplicate mistakes.

And, honestly, I'm just split 50/50.

I can come up with about 100 reasons it was loss of radio, and about 100 it was just pilot error with an underpowered/too heavy plane. Further review of where I was in the field, the known wind conditions in those areas, etc etc etc, tells me that, bluntly, EVERY single thing the plane does could be either pilot error or intermittent radio function.

Don't MOST planes tip stall the same way? Sure they do. That says radio problem. But CAN a plane tip stall opposite directions? Sure...pilot error.

DO planes USUALLY go nose up when in a stall condition? No. Radio problem. COULD one? Sure (especially given the known swirling conditions in that part of the field). Pilot error.

*shrug*

I mean, honestly, in EITHER case, it boils down to my error...either I DID lose the radio because of my own mistake with the battery wires, or I stalled it because of inexperience and heavy build.

So, the lesson I suppose is this:

Build lighter, and make **** sure connections can't come loose. :)

(Oh...and, somehow, use this as justification to buy an EDF and practice more with non-prop airplanes. *hehehe*)

RE: Regal Eagle - A Journey
 

Sorry to hear that.

On the F-15 (red, white, blue) I notice all the tail surface had a square leading edge .(post 415) You will need to round the leading edge. If not, That will produce drag ,and turbulence. over the elevator which I think will make harder to control. All jets likes a clean airflow over the control surface.

Can i see the video?

RE: Regal Eagle - A Journey
 

Gordon,

Sorry about the RE.

The nose high attitude with an apparent tip stall is typical of an underpowered delta wing aircraft. And it won't always stall to the same side.

One of my REs weighed 12 3/4 pounds and it flew great with an OS.77. I think you need to look at your thrust tube. The thrust tube design you used will work for a Byron fan, but not the Dynamax fan. You need a single straight thrust tube with an exit around 3 1/2" to 4" or a bifurcated thrust tube with exits that are 2 5/8" each. The straight tube is the easiest to build and once in the air, it is not noticeable. If you use this type of thrust tube, you should be able to get off in around 200 - 250 feet on grass and have top speeds in the 125 mph range.

After reading Angel's post about the tail surfaces, I went back and looked at your pics. The leading edges do look squared off instead of rounded, but it might just be the pic. I don't know how much effect it would have but I would make sure they are rounded.

Good luck!

RE: Regal Eagle - A Journey
 

I haven't looked at the video 100 times, but from what I saw watching that one time, I felt like it was a thrust issue. The plane seemed to barely have speed to fly and would not accelerate further.

Gordon, I could swear I heard you chop the throttle just moments before impact? If that is correct, your battery was attached to that point.

Anyway, my two cents may not be worth a plug nickle, but I think Gary's thust tube thoughts make a lot of cents! (pun intended)

RE: Regal Eagle - A Journey
 

I haven't seen the video either, even though I was the one who recorded it. When it turned back toward the runway I was zoomed in and didn't know how far out it was...heard Gordon saying "I've got nothing" and my first thoughts were which way to run :D

RE: Regal Eagle - A Journey
 

In my experiance with the (Topgun) F-15, when it stalled it just dropped the nose and started flying again. I would think the RE should react the same way unless there is somrthing wrong with the incidence from the right wing to the left wing.............Both have to be the same.

RE: Regal Eagle - A Journey
 

With the CG forward it will react like Terry says, just drop the nose. But if the CG is rearward as Gordon thinks it might have been, then it could fall off to the side. I've never had a RE do a tip stall, but I have had a Sunset Models Sport Eagle do it. It's very similar to a RE but smaller.

RE: Regal Eagle - A Journey
 

Gboulton

RE: Regal Eagle - A Journey
 

Gboulton

Sorry to hear about your loss. Last year I lost two in the early spring. Previous year I had lost 2 at the end of the year. Since it was my first year flying rc and I had progressed pretty quickly (due to my CL aerobatic and 100% scale flying) I wrote them up to inexperience. After all, one was a 4 star 60 with a ST .90 that I lost after a zillion turn inverted spin that I tried to fly out of without breaking the stall. Three stalls later I lost it. Seemed like me. Then there was a Cap 231 2 weeks later. 231's are known for snap turning and I had a funny sounding engine so I set up an emergency descent to the field. After I turned final with still plenty of alititude it suddently snapped into the ground. Must have just been cap antics. But in reality, this one had me befuddled. I was straight and level, with plenty of altitude and should have had good speed. Still, first year, a cap known to be nasty among caps...

In the spring I lost a 3 D foamy electric. Climbed out, banked hard right and went in. No reason. Perplexed. Finally I lost a wonderful flying Vector flight Extra when while flying dead level across midfield it pitched nose up verticall, did the snaps and impacted the ground.... and I never touched a thing to trigger it. And nothing I did would recover it. No response the plane made related in any way to what the plane did. There was a radio problem here. No question about it. A freind was watching the plane and my thumbs and confimed my inputs were not what the plane did. This airplane had an onboard battery indicator... batt was charged. Range check was at 100 ft with solid lock. No other receivers on at the field. I had sent back all the receivers of each of the involved planes. One was replaced by the manufacturer as "intermitant" but with no other comment. I was starting to suspect a possible issue with the transmitter and it turned out I was right. It was returned and repaird for being "intermitant." The receiver was fine. By this time I had pretty much lost faith in this radio, as well as this radio company. I had gone with their gear cause it was advertised and revied often. It was a full comuter radio, company's top of the line. Company even repaired any damaged servo at no charge.. they just sent a new one! I ordered a radio from another company and began replacing my receivers as well. All the equipment as well as all my servos had been from the same company. My new radios have given me zero issues and I have lost not a single plane to a radio issue.

But it all started with one first crash where it just did not seem like the plane did everything I asked. There was enough power on the 4star to hover it and it did not pull it out of 3 consecutive stalls. Yea, it still may have been me.... but it did turn out to be a radio issue. I'd send the transmitter and receiver to be checked before flying with them again. You may find out you did do it right and the plane may have been fine. Just a thought. All my radio range checks were fine. I do it every day on every plane antenna down at 100 ft.

Now go out an Yak it up and enjoy flying. Come back to the jet when you are refreshed.

Bob Branch

RE: Regal Eagle - A Journey
 

Very sorry to hear about your plane. I live in Brentwood, and am into F-15's also. Give me a call at 615-373-2963. I might be able to help.

Barry Grove