BH models Mosquito build

Hi, I'm new around here. Been lurking for a while and somewhat active over on RCGroups under the same name.
I also have this BHM kit, and have been procrastinating about the build. After having tunnel vision over twins for at least half my life, I thought I'd jump into a simple slabbie-hence the BHM Mossie.
I found Mike Londke's build of this kit over here:
stunthangerDOTcom/smf/12-a-building/blackhawk-mosquito/msg299852/
And I've spoken to him on the phone, as well as by email. OP, you may want to look at his pics. Mr. Londke used two Norvel Big Mig .061s. I planned on using Norvel .074s. He has told me this would be over kill, and to ensure I did extra vigilance re: engine nacelles splitting/separating from the airframe mid flight. He also mentioned he had to add quite a bit of tailweight to make up for the bigger engines. I expect this is because his are pretty far forward in the nacelles. Another thing he mentioned was that the larger engines may need bigger props...And that means moving the nacelles out a bit, or mounting the engines outboard of the nacelles.
You may want to "compare notes" against his pictures, and his YouTube video. I know the bragging rights of having the kit with the biggest engines sounds apealing...I think if yours flies, you win! I'll be watching this one as it develops.
Good luck!

Oh, and the built-up wing/profile 1/2A Mossie is from Model Airplane News, August 1968. Find me on RCGroups in the Control Line Forum. I was forwarded the plan earlier this year from a guy in England with no origin data. After months of searching, I found another forum with a build started some time ago. A little more digging yielded a copy of the magazine build. Once my BHM kit is complete, I'll build the Man one.

Welcome to CEF Jim

I found this thread last night when I was looking for some more info about the plan Bob posted.

https://www.rcgroups.com/forums/showthread.php?2741283-1-2A-Mosquito-w-built-up-wing-profile-fuselage

With its built-up wing, the 1/2A Mosquito seems interesting, but I wonder if a symmetrical airfoil would be better still?

Yes, Welcome Jim,  You may be new around here but I have been reading your Mosquito thread over on RC Groups.  I post there occasionally.  RC Groups has a large impartial population, here there is a relatively small group of participants that really get involved with each other in a supporting sort of way.  The best forum on the WWW in my opinion.  

As you know the Mosquito plans call for engines .06 -.15 so I thought the .09 would be a good fit.  I briefly thought of using .049 Cox tanked engines BB, BW, GB eliminating any need for an external tank but gave that up even though I like flying low and slow, but maybe not that low and slow.  Although GB's and BW's hauled my P-38 around quite well.   Sooo, reading your thread and your prospective use of Norvel .061's I remembered my two Norvel .049's and just for grins tried them in the .09 cradles.  They would fit with alterations but I'm going with the Enya's.  I have 51 Enya .09's just sitting so I feel obligated to do so.  I do have a "Spitfire" free-flight fuel cut-off timer that could be used but as Rene said could complicate things.  A simple Y off a main tank should do.  



And my mistake.  I failed to read the plans thoroughly.  In my haste to get started "Procrastinator in chief" I laid out the main pieces of the wing and glued them together forgetting about the reinforcing spar.  Rather than cut it out I just glued it on the front of the "radiator" in a much less advantageous position.  Live and read.  



Thanks for your comments guys, keep them coming and keep me honest, a difficult task.  And Jim, looking forward to reading about your build.  I wish more here would post theirs.  I am hooked on twins.  There is nothing like a pair of engines rotating in sync.  A wonderful sound.  I will look-up the stunt hanger fellow look at his youtube and read his thread.  I wonder if my .09's will have the same nacelle effect.  Guess I will have to beef them up a bit. It's curious that he had to add tail weight with the engines located close to the CG and the Mosquito having such a long tail moment.

Bob

Here's one for you Bob

http://www.outerzone.co.uk/download_this_plan.asp?ID=8409

OK, I'll stop the hijacks now

The Mossie is looking good!

Bob good catch on the spar and I tend to think it will do the same job where you added it but may add a tad to nose weight

On each engine nacelle, mount, profile... I would certainly add glass, carbon veil, or silkspan to at least one full side

Once installed I would also do full, both side, filleting to the wing

RE: Your indecision on cylinder placement.. and I know YOU know this: both cylinders out- is gonna provide the most consistent engine running and obviously place the NVs up (a good thing)

I certainly would be researching on all small twin models on each of the sites to see what many many scale and semi scale guys do to get their engine runs stable for the competition flights

Do Not hesitate to PM some of the Stunt hanger Scale Twin 1/2a competitors and ask their advice....too many have been there done that and do know what works BUT better yet, they absolutely know what DOES NOT work

Fred Cronenwett comes to mind as a guy who should know that exact model and what works

KariFS wrote:Here's one for you Bob

http://www.outerzone.co.uk/download_this_plan.asp?ID=8409

OK, I'll stop the hijacks now

The Mossie is looking good!

Keep the hijacks coming Kari, I enjoy them and learn something. Yup, that's a project. But I have a new love. Two burning, and two going along for the ride.

https://www.youtube.com/watch?v=F-5kX-4gRr8

Bob

Hi Bob,

I think the plans indicate a single .15. ISTR it was one sentence buried in the plans.

They also indicate a recommendation to not install the landing gear if using small engines. I think Babe Bees would fit this category; GBs, BWs would be stronger, but the bottom spec's engines start at .061. I wouldn't have bought this kit had I seen that BEFORE ordering.

Once you see Mike's Mossie I think you'll note how far forward his .061s sit. The props stick past the front of the fuselage.
Since your nacelles are completed, consider splitting the wings to slide the nacelles back a bit.

Mike and I talked at length about this kit. He installed big tanks, only because he had them in hand. He mentioned 1/2 to 3/4 oz tanks would be more than enough. I have no Enya experience, so I can't recommend anything other than watch for a lean inboard engine onless you run pressure with your single tank.

He was very quick to say this is a heavy model. Watch his video...Once the last engine quits, the plane drops! He says he flies low once he loses the first engine

Another thing to watch for...His outboard nacelle split and left the plane. He wound up using square stock between the nacelles and wings. They are most evident on his underside pics. Another recommendation was to fiberglass tape the fuse to the wings, and the nacelles to the wings. He also recommended ply doublers on both sides of the nacelles.

If I stay with my .074s, then I think I'll remove the "tongue" between the engine bearers in order to slide the engines back to the leading edge. If I do that, I may cut out the wings to drop the tanks into them in line with the engines, or mount on top of the wings. If I get really creative, I may leave the engine bearers long/wide enough to use 1/8"  aluminum brackets so I can flip-flop between rearward mounted Norvels, and forward mounted Medallions.

Wherever mine wind up, I plan on at least drilling two or three holes vertically through the nacelles and wings...And epoxying baboo skewers all the way down. Basically, I'll try to pin the parts together.

Lastly, and off topic. You mentioned a P-38. Since this is a Cox forum, any chance it was a Sterling 1/2A profile model? I picked up three Dave Cowell reproduction kits (Aero-Werkes)...Two Scientific built-up wing/profile fuselage (Typhoon, and FW-190), and the Sterling P-38. All three are designed around Babe Bees.

In the meantime, I'm enjoying your build...If you and I finish around the same time that makes three in the air that I know of.

Thanks for the advice Fred, food for thought.  I think I will probably wind up trying several engine configurations before any air time.  I debated on how to tack the wing to the fuselage finally using just plain old wood glue.  Had the option of epoxy or tacking with CA.  Later I will final glue with a fillet of this self mixing epoxy which lays a nice even bead.



I scribed a witness line 1/8" out from the center line squared with the "radiator".  I have never been much good at the string method each wingtip to center tail fuselage.  Then brushed on the wood glue top and bottom and slid it on.





Longitudinal alignment was fine, but vertically the fuselage tended to lean right.  A little strategic altering was required.



Engine nacelles are next, then the tail section.  I have already applied and lightly sanded two coats of sanding sealer, once completed I will hit it with some Top Flight Lustrekote primer, then a off-white satin and olive green camouflage finish.

I found a picture of Mike Londke's Mosquito.  He just rubber banded a couple of tanks on and flew.  I love it, sometimes simple is best.  Looked at his flight video too.  Wow, that fast with the Norvel's.  I may need 50 -70' steel lines with the Enya's humming.  



Ha Jim, we hit send at the same time. Happens alot, if you see it just wait and hit "save". Got to finish reading your post.

ob

We think alike Jim.

My P-38 was scratch built many years ago. See thread here:

https://www.coxengineforum.com/t10584-cox-powered-p-38

Gotta run. Bob

BOB I wouldn't use that 1 min. or even 5 on the stress factor of the plane ,,, Heck i wouldn't use it on it at all for that matter it want have time to sink into the wood and get a good grip before its cured !!! Get or use 30 Min It and U will bee more happy in the end ...

getback wrote:BOB I wouldn't use that 1 min. or even 5 on the stress factor of the plane ,,, Heck i wouldn't use it on it at all for that matter it want have time to sink into the wood and get a good grip before its cured !!! Get or use 30 Min It and U will bee more happy in the end ...  

Good point Eric. I used to use 30 minute all the time from Tower I think, but I got away from it for some applications when someone got me started on Tite-bond wood glue. I wasn't a believer until I saw crashed models where the balsa tore away leaving the tite-bond joints intact. Talk about wood penetration. I always back it up on critical joints with epoxy though.

Darn, I was so engaged in trying that bead instant mix for fillets. But you make a good case for the 30 minute stuff.

Bob

Jim, It's just a coincidence that I found and posted that picture of the underside of Mikes Mossy.  I saved it to my file as a memory prompt as at times my near 80 year old brain gets muddled.  At times?  

As mentioned my P-38 was scratch built, but I long for a profile Sterling kit.  Guillows as you know has a P-38 kit that could be beefed up to handle Cox .020/.049 but anymore they are just to complicated for me.

I bet that this model would fly quite well with a couple of nicely tuned Black Widows pulling it even with landing gear on.  Maybe no close to the ground wing-overs or loops though.

As I recall I removed about 50% of that tongue to get the placement of the Enyas where I wanted them and thought about using some sanded luan mahogany as backups to the kits doublers.    I didn't though, hoping that they will hold together.  

Using those bamboo skewers down through the nacelle and wing is a great idea.  I use them a lot but stout tooth picks may be an option. That captured wing isn't going anywhere but I am thinking about using some triangle balsa epoxied in (30 minute stuff Eric) as back up for both wing and nacelles.

Just mounted the landing gear struts to the nacelles, took some bending to get them straight.

Bob

  http://www.ebay.com/itm/VINTAGE-STERLING-P-38-LIGHTNING-TWIN-049-24-U-CONTROL-BALSA-MODEL-AIRPLANE-KIT-/201812473565     http://www.ebay.com/itm/Vintage-Lockheed-P-38-Lightning-STERLING-Wood-Model-WW-II-Airplane-Kit-S-17-USA-/162374175828

OK...Last Thread Jack for me:
NFI for me; I just love the man's kits!

That top one is the smaller one...Dave Cowell of AeroWerkes reproduces this one. Look for Airsoft Brenda's YouTube video. She showcases an electric one (Oh, the travesty!). My Typhoon on RCG, or my FW190 has Dave's SRK (short release kits, or limited runs) list.

I would buy one of his lasercut kits before working so hard to find an original die-crunch one.

How do I add pictures? I'd love to show y'all how he packs them.

Never mind...Found the magic button!

Ok, with push fast coming to shove I had to make a fuel tank decision. Most may not like it but I had to tank the single tank concept and go for two one under each wing snuggled up to the nacelles.

In order for the only plastic tank I had that would fit I would have to place it vertically beside the fuselage for proper fuel pick-up. Horizontal wasn't going to hack it, that and the longer fuel lines made it impractical.

So, looking at both options I got on ebay and found these, virtual clones of the one I have.  



Less drag, less fuel line, less work. And yup, I will do pressure checks.

Jim, Welcome to CEF. I don't think the forum will allow you to post links including pictures during the first week after you join.

Bob, Fred said it before I did regarding the engines. I really like the look of opposing cylinders, but I'm pretty sure the fuel flow through the bypass ports will be significantly different between them due to the Gee forces of flying in a circle. Getting a consistent tandem run might be pretty troublesome.

As far as tank(s) are concerned, although I'd be hesitant to cut the fuselage for a center mount, any of the aforementioned configs will work. You can probably guess what I would use. I wish I could fly out to your shop and demonstrate how much easier it is to set up and use a pressure bladder than any other type of fuel supply. Even without having to change needle valves. That being said, the two wedges you chose would be my second choice. Make sure(I know you know) the outboard engine shuts off first.

This has been a really interesting build thread so far. Thanks for engaging us.
Rusty

Love the twin-build so far Bob. I'm not sure how far you've gotten into mounting the engine nacelles.. but take heed to what Jim mentioned regarding a fellow-modeler's nacelle "departing" from the wing during flight. When you showed photos of the balsa nacelle splitting prior to assembly.. it had me concerned about reinforcement. IMO.. the ply doublers supplied should be discarded for full double-sided ones with reinforcing fillets. Full doublers might even help dampen vibration which could lead to fuel-foaming. Are you set on running the Enya .09's? I'm guessing that they're on the heavy side.. and could use the extra support.

Being a "flat-wing" model.. it's gonna' drop like a rock when the engines shut-off. Coming down hard on the main-gear will stress those nacelles more than any other part of the model.

I think that your choice to run dual fuel tanks is a sound one. No telling whether a single tank with a Tee-fitting will feed both engines adequately and evenly. I agree with Rusty; in that both engines should be oriented the same. I'd go with outboard-facing cylinders if it were mine. That would eliminate some performance variables. You could opt to start/tune the outboard engine "first".. which would burn-off some fuel for it to "ideally" quit before the inboard engine.. and/or fuel the outboard engine with 1-2cc's less fuel.

You may want to pay special attention to the recommended lead-out guide placement for a "critical" engine-out scenario.. as well as rudder-offset. These things all add-up to what "could" happen on the maiden-flight. Applying safety-measures might slow the speed of the model.. but could also make it more controllable under power.. and with either engine shut-down.

Bob, You inspired me, so I started my two Pee Wee! ... I hope you like the video!

Got them singing Nicely Mauricio Bob , good thing some others have chimed in on the engine placement , what looks good may not always bee best As Roddie said i agree about strengthening the mount area and the offset of the rudder a plenty since you're not concerned with fast stunt speed . I think it was Phreddie that suggested to discard the old bearers and make new all the way back to the wing both sides ! I know to many ideas can blow your mind when building but safety is a issue . Eric

Thanks everybody.  I'm sure bladders work best, constant fuel supply pressure and all that, but I just don't understand the employment.  Captured bladders, free floating bladders, balloon bladders, etc.  Seems like filling them would be messy and would be subject to bursting.  I'm not smart enough to figure all that out.    Maybe if there was a commercially available system.  

And Maurico, I always enjoy your productions.  Two Cox engines off a single fuel supply was an experience to behold.  Love that sound.

I am locked in to using Enya engines although a couple of Cox .09 Medallions may work better.  But I could use two of the early smaller lighter .09 Enyas.  But chances are either my son or I will plant this thing firmly into the ground and I don't want to risk them.  (Then I think of Kim running all those RR-1's, Space Bugs, and Space Bug Jr.s a couple of miles up with no concern)



But, again you have convinced me to back up the nacelles bearers.  I have a lot of scrap luan mahogany from which I have used my belt sander to sand off a veneer or two and use as firewalls, ought to work for the nacelles too but at a weight gain.  Yes, "fall like a rock" when the engines quit and the nacelles take the impact.  Going to just reinforce one side though.



Nothing is glued up so I still have the option of switching the struts, in or out, would not make much difference.  I put them outside as attaching the keepers using a screwdriver would be easier,  but I'm changing the supplied wood screws for 2/56 machine screws and nuts so switching the to the :correct: way would not be a problem.  



Going though my unbuilts yesterday I rediscovered this built-up wing Lockheed Electra using Cox .049's.  Yippee, no fuel tank placement worries.  My next build.



Cowls too.  



Bob

To nice a day here today (rare) to spend inside so I ran the Enya .09's that I will be using on the Mosquito and cut out the luan reinforcements for the nacelles.  Engines ran great although a PO of one of them really beat-up the NVA assembly, but that one was the best runner.  Got about 90 seconds out of half an ounce, more than enough to make me dizzy.  



Now to glue on the reinforcements sand/file down and drill some holes.  



Why do I post so many pictures????  I dunno, saves me a lot of splainin'  

Bob

Rub it in Robert.... I'm messing with a swimming pool issue in freezing weather..

That's ok... I'm enjoying reading about your build! The more photos.. the better! I like the stance with the struts/wheels installed!