Maschar

TXmustangflyer, how is your mustang going? Thanks for sharing!

Txmustangflyer

Bad Left main actuator. Waiting on them to come back in stock, so stalled until I can get a replacement.

Maschar

Understand, hope it will be back in stock soon!

Maschar

Anybody here glassed H9 P51?

Maschar

I would like to put some 4 stroke engine in H9 P51. What engine you fly guys in your Stangs?

Txmustangflyer

Performance unlimited "promod" Zenoah G62. It has benched with a 23x8 xoar scimitar at 7800 rpm. Also benched the ramoser at 6200 rpm 14 inches pitch, on the ground.
Estimated hp at 7800 7.2.



Estimated top speed..somewhere between 95 mph and 100 mph

Yes, it tucks in the cowl quite nicely. Picture taken before final trimming which was mainly to address possible cracking due to vibration and getting rif of the saw teeth.

spitfire66

Hello,

That prop is pretty cool! What rpm are you getting at 8 or 10” of pitch? (If it can adjust that fine). 6200 sounds like quite a load. Have you installed baffles for cooling? We (My flying buddies) use dyrese foam. It cost less than $2 and adheres with ca like an sob. Very easy to work with. Also, did you do anything with a p-38? I ordered everything I can buy from ziroli. I’m curious if prekin can make better parts than the abs stuff, in particular, the turbos.

1021millerm

I know this is an old thread but I’m hoping someone can answer my question about where to put the cg on this plane. The manual suggests to put it at 6.5-7” but in order to do this I need to add close to 3 pounds of weight which seems out of control to me but if I don’t and it’s tail heavy then I’ll really be out of control. I haven’t added anything to the rear of the plane so I can’t figure out why so much weight is needed. Help please!

BarracudaHockey

My Feedback: (11)

It's been a while but H9 always had pretty conservative CG ranges so I'd start at the absolute rear of their range.

I did need weight though I forget how much but it was probably quite a bit, nature of the best with a WWII warbird, anything close to a scale outline had a short nose and a very heavy Rolls Royce Merlin V12 engine up front and replicating that with our lightweight aluminum engines means lead.

TXKflier

Put the CG at 25% of the MAC. There are websites that will help you calculate where that is. I set the CG based on how much forward stick (down elevator) I have to use to maintain level inverted flight. More than 25% from stick center is too much, and if the plane climbs on its own when inverted, it's tail heavy.

There is no perfect CG location; it's a personal preference, provided the plane is stable.

1021millerm

Appreciate the response, I’m new to large scale warbirds which is why I’m nervous about the cg, I have plenty of other large scale planes though. With no weight added to the plane yet it weighs in at 28.5 pounds, all the movable weight is currently in front of the CG so I can’t gain any ground that way. Anything I add at this point would be dead weight, I guess I’m just really stuck on wanting to keep this under 30 pounds but don’t think it is possible. I was planning to epoxy the lead in the nose so I was hoping to get close on the first try but I guess I’ll have to refigure and experiment. Thanks again for the response.

BarracudaHockey

My Feedback: (11)

I'll see if I can dig up my article, that should have the final weight.

ForcesR

This program will relieve all doubt where the CG is located on an RC aircraft. It has never failed me in locating the CG on my many RC aircraft. https://rcplanes.online/cg_calc.htm

Roger.

1021millerm

Well I used the calculator and it gave me a cg that was even further forward of the book so I’m just going to stick with the book for now and see where we go. Sure enough I added 3 pounds of lead to the nose and It balances directly over the 6.5-7” mark as the manual calls out, move your fingers to 6.5 it’s tail heavy, move to the 7” mark and its nose heavy, center of the marks and it’s spot on. Thanks guys for your help! I plan to maiden it this weekend and hopefully will be able to report back with great results as well as some data for the next guy who asks the cg question about this beautiful plane.

1021millerm

Well, after a successful maiden flight 3 pounds in the nose of my plane was perfect. I had plenty of elevator. It did not nose over on takeoff and had a good glide rate as well. If anyone is wondering, 3 pounds is accurate. It’s not overkill, it takes a lot of weight in the nose to balance this plane, unfortunately that put my plane 30 1/2 pounds plus fuel. Thanks everyone that responded appreciate the help. Hopefully this thread helps anybody in the future who has the same question.

BarracudaHockey

My Feedback: (11)

Good job, thats still one of the best flying big mustang models out there.

1021millerm

So now that I have around 10 flights on this plane I have a few recommendations for future builders of this plane. First thing first and take my opinion for what it is but this plane flies great and lands super easy, bring it down with full flaps, keep it a few inches over the runway and chop the throttle, it will set down on the mains and carry the tail a long way for a scale landing. Takeoff is easy as well, throttle up slowly, a touch of right rudder when the tail is flying and slowly add a touch of elevator, shortly down the runway it will liftoff with ease. I really love this plane to say the least but it isn’t without flaw which I will get into shortly. 22x10 Xoar propeller is getting me 128mph and it isn’t even broken in yet, I’ll be going up in pitch to a 12” to see what I can get once this engine is broken in.
second- don’t skimp on the exit air, this will overheat really quickly if you don’t give the engine plenty of breathing room. Third and this is kind of important, when adding weight to the nose as I did, (lead shot epoxied into the cavities made by the wood structure) use some fiberglass in the cavities before you add the weight. The nose of this bird is a bit weak and cracks from flex, weight, and vibration if you don’t reinforce this area. Live and learn I guess. Last recommendation I have is that you save yourself some headaches with the gear doors if you decide to use them and buy yourself some 180 degree servos to get the throw you need without adding a huge servo arm that steals servo torque. You can make it work with a standard servo, however the arm gets long so get more torque than you think you need to overcome the prop wash. The gear will work all day long on the ground but once in the air they will get hung on the door if the servo is too weak. I used 130 oz/in servos and as long as I get the gear up as soon as I’m off the ground I have success, if I’m cruising they will fail.