As an auto mechanic for 44 years. A quarter turn around the bottom sprocket is really not enough to reliably transmit much torque or to be reilable for flight. You may need a sliding captured bar with two idlers above the crank to create almost half a turn of belt around the crank sprocket. Make sure the sliding bar has enough Y to prevent it from folding up into the cam sprockets. I would love for you to invest in a carbon pile and a multimeter with long leads with decent gator clips. Hook the carbon pile across the positive starter post and the engine block or starter mounting stud then set the volt meter to 20 volts DC. Hook one lead to the starter top post and the other to the positive battery post. Turn the carbon pile to 300 amps and watch the volt meter. I would like to see less than 2 volts of drop on the positive side of the starter battery circuit. Next test. Move the multimeter test leads to the starter body and the negative battery post. Turn the pile to 300 amps. This is only for a few seconds. Less than 2 volts of drop on the negative side. Puffing black. Almost sounded like you hydraulic locked the engine with fuel. Please pull all the spark plugs. Do a compression test. Make sure you have not bent anything like a rod. If you are trying to start the engine from a jump start box. Autozones sell a marine group 24 and 27 starting and deep cycle battery for 100 bucks and core. They also sell various lengths of battery cables. And red tape to mark the positive. I am not your average mechanic. There is no reason to not have CO2 fire bottles sitting within the wingspan of the plane. And a nomex driving suit on anybody in the cockpit operating the starting controls.
I concur on all points made here. During start the setup as shown will have too much of a voltage drop at the starter especially as the cheesy cables get hot. Also, depending on the torque/timing requirements of the bottom pulley (simple pump vs. critical timing), 25-30% engagement of sprocket may or may not be enough. Hopefully the belt is part of 50 hr inspection minimum. Keep up the great work.
Yep, it was modeled after North American Mustang plans. The wing design is different, so it has a more docile flight characteristic. I appreciate you watching my videos!
Wow! Very exciting to see Jan's airplane out in the sun for this test run. Very sorry for the glitch, but it appears you guys are very much on op of it. Curious though from the Test Stand Run of approximately 3 hrs. if those two internal areas were rubbing at that time as well. Keep up the awesome work guys. Praying for a successful test run soon. Wishing everyone involved a Blessed Day... Larry W. Ocala, FL. B-777 Driver & Future S-51D Owner.
Larry, when the engine was ran on the test stand, none of those components were there. It was ran as if it were a car engine with carburation, regular oil pan and water pump. That was done a couple of years before the ADU was manufactured. Appreciate your comments. Stay tuned for more excitement.
Put a belt tensioner on the belt to increase the belt wrap around the crank pulley. Put a flywheel on the propeller flange to absorb starter motor and power pulse shock to the belt work. The propeller alone would fix this as well.
That accessory housing and the routing of the drive belt don't look right to me. The amount of belt engaged with the lower sprocket isn't sufficient. How did the parts that were rubbing come into contact with the case? There should be bearings and/or spacers to keep them from moving closer to the case.
Needs some idlers and a tensioner. They need to look at current automotive belt dirve systems. Even then the belt is only turning the cams, not transmitting all the engine power. Also look at supercharger dives an fuel dragsters
The only thing the ADU with its associated belts and cogs is accessories. This engine does not have overhead cams. The cam in this engine is driven off of the crank the same as a 1955 chevy 265 and is very reliable. The are support bearings and spacers for every cog that should have prevented this from happening. The proof will come the next time he tries to start it
bad design. clearances are not the issue. too much counter torque (load) on that drive assembly ( which is not drag) you need gear drive assembly. that belt will never hold . its not clearance guys. the belt spread (got wider on the gear) from the pulse counter torque load on gear . thats why it hit the sides where the gears are. it only hit when it spreads from the pulsing load of the gear. . It is a pulsing load , so the belt expands where it laps over the gear on moments of high counter torque load on the gear. the belts spreads , masses onto the gear from counter torque load. You may get lucky and get her started with it, by giving more clearances to stop the rubbing, which will make you think you have the problem solved. But the pulse counter torque load on the gear will still be there and the pulse spreading of the belt on the gear will remain. the belt will snap in short time as it is constantly being mass spread on the gear. you will end up crashing from that setup. you need GET RID OF belts. use all gears. make an idler gear and drive gear setup. gear drive will make more of an authentic P 51 sound too. I built hundreds of motors. Every single one started one first crank , in less than 3 seconds. Every one, over 40 yrs.
I have never been a fan of toothed belts they are at the bottom of my preferred list which goes gears, chain and only as a last resort belt. I am surprised this problem did not show up in the test cell unless of course this auxiliary drive system was not mounted then.
When the engine was ran in the test cell it was using a carburetor and no aux drive unit. This was the first start attempt using injection and this ignition. Jan is currently reinstalling all the systems to prepare for another start session
There is a flywheel for this engine as in any automotive engine. For these initial starts, Jan didn't to make being around the engine more dangerous. When the engine is running reliably then we'll install the propeller.
Nice! When starting and running, doesn't any engine (other than an F1 racing engine) require an inertial load - a flywheel, or in this case, the propellor to run properly?
Yep. My io360 Lycoming has a flywheel but not heavy enough to sustain engine rotation. The mustang has a heavy flywheel, therefore doesn't need a proper for initial runs
@@mustangbob51 Thanks for the reply. Given the need to be judicious about weight in an aircraft, I assumed that the propellor would serve as the flywheel, and the starter might turn a simple ring gear.
Seen plenty of domestic iron run on homemade engine stands in people's garages with only a flex plate on the back and live long lives thereafter. For breaking in flat tappet camshafts particularly, it's desirable not to have that inertial load. You want to be able to start it up and rev to 2000+ rpms immediately for the break in. Obviously long term your statement is true but you're not going to hurt the engine running it without an inertial load for an hour or two.
What would an airframe like that do with a Chevy LS engine? I have an LQ4, supercharged. It has done 1250HP with 24PSI boost. The road setup was only 860HP at 9 PSI 7000rpm. I am trying to talk my kids into putting it in an airframe, they want to keep it in a truck but are not hostile to something with wings. Only problem is we only fly nose dragers we are not tail wheel certified, I know minor. I gave the engine computer maker a goal of 4800rpm and 12lbs boost. He said 850-950 HP without emission which it now has. He thinks he can hold 12PSI to 20,000 feet with my blower. Could I fly an airframe like that on 800HP? You may have cost me more money but it will be fun.
Jan purposely kept the HP down to make it more reliable. We anticipate a 200 hour tear down and inspection to make sure of the condition to insure that reliability
My background with timing belts are with much smaller CNC/servo types but I have had problems with the lack of tooth engagement on smaller drive pulleys like you are using. I'd be concerned with even with a low accessory load the belt could slip during high acceleration/deceleration like commonly seen in aircraft use.
so, aside for the clearance problems that we had, there is not a lot of horsepower required to turn the accessories on this engine. also, when the ADU was being engineered, the belt manufacturer was consulted regarding tooth engagement and tensions. these were all complied with for purposes of the build. I've just uploaded a video with successful runs of this beast. check it out! thanks for watching!
The HP is calculated at 6500 @ 4800 RPM. i can't remember what the weight is, but it's all aluminum block, heads and intake, so a fair amount lighter than as iron block one. I will try to get an answer on that and get back to you.
Just speaking for myself personally, if I was going to go through all the trouble to adapt a BBC for aircraft usage, I would not have chosen mechanical fuel injection. EFI with a return fuel system would have been my choice, probably using something minimal like megasquirt to control it. Especially considering you're using boost, you lean that thing out and you're going to throw a rod though the pan. I'd of also probably used a big cube LSX instead of a BBC, but that's a whole other discussion. The electronics are easier with the LS because you can use stock computers with HP Tuners and so forth plus they will reliably make 1000+ HP with the right parts.
Several years of engineering and input from several other operators were involved in the development of this ADU and PSRU. The result of this collaboration is the product that you see in the video. These are working well in the 4 or 5 other mustangs using them.
Because we all know this is a copy of the P51 I don't think I would have cluttered up the engine bay with anything phony like Make believe exhaust stacks or anything But I guess it was important to make it look like it has the Merlin V12...when anyone with ear's can clearly hear the sound of the Big 540..I liked the look on his face with the Starter Bendix started talking But all this is a part of the process when your fabricating one off parts ...
Those are radar mapping birds that Dave and Jan have been maintaining for years. They currently have no mission and the engines have been sold off of one of them. Those housings cover the radar equipment for the mission profile
@@mustangbob51 #DIYLipoSuctionWIthAShopVac ??? It's a business model I'm working on. I figure I just need a few seedy alleys & a 70's Van & I'll bee in business. 😜 Aaaah, to be young & thin again!
@@aviation.satire please don’t think I’m being rude. I also have no experience personally, so my opinion is worth noting. I have seen ecu issues due to limp mode. I have also seen lots of PSRU cause trouble as well. I also know of valve train issues as well. I just love mustangs and airplanes and big block Chevys. I hope nothing but the best for you.
@@oneiam1533 nope was just curious what you had seen as well I want to get a Stewart so I was seeing what else I could research about the Chevy big blocks
@@aviation.satire ignition failures I think. There are dead stick crash landings from these engines that were approved for aircraft use. It's beginning to look like a failure
The belts just turn the accessories. Water pump, oil pump, scavage pump (this is a dry sump system), alternator, prop governor, ETC. The cam is driven traditionally off of the crank with a chain just like originally designed by GM a hundred years ago
no mike, the cog belt driven accessory drive is the result of several engineers and a couple of years of research to create the unit. 4 other of these are running without difficulty.
it's not necessary at this point. we have a lot of checking to make sure that there are no leaks or other potential problems. having a prop swinging out there makes it really dangerous. the prop will go on as soon as the engine is operating properly.
You are correct. This is Jan's first attempt at starting this engine in the airframe. There are 5 other Stewarts that are configured with the systems that he has added to this plane and he has had a stiff learning curve with regards to starting. The first time I started my Lycoming IO360, I'm sure I had an befuddled look on my face also. And he had the added confusion from the problems with the ADU
thanks for the comment Twister. the interesting thing is that there are 4 other ADU's just like Jan's currently flying. it makes no sense to us. i'm getting ready to do an update on Jan's mustang regarding how the engine was built and the precautions taken to ensure a really strong engine. be sure to stay tuned
It looks like the fan is connected to the harmonic damper. With little clearance it will cause a low pressure away from the engine, just like blocking a vacuum inlet. If the harmonic has a rubber separator it will cause it to expand axially. If the rubber is damaged it may have moved towards the external housing already. Why does it need a fan anyway? That belt design is not good in the mind of this engineer. I don't understand why your are using such a poorly designed engine also, and why are you using a distributor and magneto. No way was it designed by engineers, engineers don't use imperial measurement also.
This engine has a flywheel like regular automotive engines have. The engine is actually mounted backwards with the flywheel at the front of the airplane.
