YT / ESM Hurricane - Laser 200 in-line twin

[Peter Jenkins]

The Spit felt like a brick - wasn't mine I hasten to add - and you had to think hard about how to manage the limited energy.  The OS 91FS seemed up to the mark based on my OS 91 FS in a Top Gun Bucker Jungman.  The Jungman is a delight to fly in contrast although, as per full size, needs to be dived to get to looping speed that no self respecting Spit should need.  The other problem we also suffer is the lack of momentum that the full size has so throttle management is needed far more to replicate the full size flight characteristics plus low control surface travel as you often point out.

[Ron Gray]

1 hour ago, Paul De Tourtoulon said:

Watch carefully  the video Chris as he leans over to turn them on,,,

Appearances can be deceptive! I was actually slightly to one side and the prop arc to one side of me!

 

Regarding the restraints, wing ones are, imo, better than a tail one as the wings are somewhat stronger than the tail. The ‘tools’ are in fact long bladed screwdrivers, the shafts being over 300mm long, pulling those sideways out of the (hard) ground requires a lot of force. You will also note that the only time the motor was running at full throttle was when I was restraining it by hand.

 

Whilst I appreciate that familiarity can breed contempt I have used this setup for countless numbers of engine runs over the years without any issues, but despite this I do double check the restraints before a run. I do however take on board comments made; never too old to learn!

[Ron Gray]

Interesting comparisons of weight:

 

Hurri - 8Kg (3.5Kg in the wing alone!)

Mustang - 7Kg (fuse the same weight as the Hurri despite having the smaller 160 in-line)

Sportster - 7.75Kg

 

The Mustang hasn't got unlimited vertical performance but I think I manage to fly it fairly true to scale.

The Sportster, again hasn't got unlimited vertical but I would say that it has more than the Mustang.

 

I'm therefore expecting the Hurri to be very similar in flying characteristics to the Mustang.

 

 

[Ron Gray]

5 hours ago, Chris Walby said:

Did it need any lead to achieve C of G out of interest

Now therein lies a story. The manual states a C of G at 130mm but various forums seem to suggest that 120mm is a better location, the most annoying thing is that I can't remember what the location was that I had on my previous one and whilst it was written down that bit of paper has gone (build manual that I though I wouldn't need again!!!). So in order to get the 120mm location I've added 600g of lead but that is without the cowl on as that is how it will be for its maiden flight.

[Chris Walby]

6 minutes ago, Ron Gray said:

Now therein lies a story. The manual states a C of G at 130mm but various forums seem to suggest that 120mm is a better location, the most annoying thing is that I can't remember what the location was that I had on my previous one and whilst it was written down that bit of paper has gone (build manual that I though I wouldn't need again!!!). So in order to get the 120mm location I've added 600g of lead but that is without the cowl on as that is how it will be for its maiden flight.

Thanks Ron, just confirms to me (although others knew anyway 😆) that there are no issues with fitting the inline engines in this type of warbird and thinking the C of G would be too far forward! Plus it will be easy to move the C of G back should you want to later date by removing lead and reducing the AUW at the same time, always beneficial.

 

Date for the maiden?

 

[Ron Gray]

Maiden should be either this Sunday or next Thursday, it really depends on others booking the same days as we always need a spotter when we fly!

[Kevin Fairgrieve]

13 hours ago, Ron Gray said:

Maiden should be either this Sunday or next Thursday, it really depends on others booking the same days as we always need a spotter when we fly!

Hmphhh.

 

Cant make either day, but I see you have company on Sunday. 🖕

[Jon H]

Ron do you happen to have an incidence meter? If so i would be interested to know the incidences on the YT Hurricane as i am still trying to decipher the weirdness of a friends seagull example. I checked the incidences and while not as bad as i expected,  the wing section has no aerofoil section at all and so its likely the two are combining to create the weirdness. 

 

As the outer wing panels detach there is the chance to build new outer wings using the YT wings as a template. Lets face it, a fuselage is hard to screw up so it must be the wing. 

[Ron Gray]

I do! I 3D printed the parts so that I can use my Smart Angle as one. Will measure it up later.

Edited September 23, 2022 by Ron Gray

[Ron Gray]

2.5°

[Ron Gray]

Couldn’t resist! (Yes, that’s a lump of lead strapped to the motor!)

 

Edited September 23, 2022 by Ron Gray

[Paul De Tourtoulon]

Is that your idea of a damper to soften out it's vibrations ?.😆

[Chris Walby]

Apologies Ron for sounding critical or just plain whinging, but the more I think about this the more uncomfortable I am with the lead installation. I don't know what the melting point of the cable ties is, but with the additional vibration/compression of the bedding material I would not like the lead to move or break free. If the cowl was on it would not have to far to go, but with the cowl off its either going into the back of the spinner or be ejected out the back. Unlikely anyone would get hit by said lump of lead, but it sure would hurt if it did, but more to the point of trying to control a model with a more rearward C of G than wanted. 

 

Not sure where the C of G is without the lead, but it will make it one exciting ride that I would choose to avoid at all costs (vid of Ta154 available on request 🙄 and that was as plan!) if the lead falls off mid maiden. I ended up using s/s bands, longer engine bolts and a screw through the lead to anchor it all down on my hurrie and even it needed tightening down every couple of flights.

 

All the best and I am sure it will all be ok on the day.

[Paul De Tourtoulon]

Looking at his work so far Chris I am sure that it is only temporary while he sorts something solid out.

[Ron Gray]

Spot on Paul! I am working on a threaded rod attachment in lieu of the ties, although they are high temperature ones. In fairness, the lead nose weights in my Sportster are held on to the engine mounts with standard cable ties and have not shown any signs of movement in what must now be approaching 50 flights! What cannot be seen from the photo are the channels cut into the top of the lead weight to prevent it moving, so ‘I do think it highly unlikely.

 

@Chris WalbyIf the lump of lead did get ejected then the C of G would move back 10mm. It wouldn’t hit anyone as I do not fly over people or close enough for it to get thrown into anyone standing behind the pilot’s box. 
 

As always, constructive criticism is always welcomed so keep the comments coming!
 

[Ron Gray]

This is the latest incarnation of the ballast fixing, I still need to turn the hex bar down to make to look a bit less Frankenstein and will probably change it to through bolts for the vertical fixings! At least this way it gives me scope to have differing balance weights to put in place if I find this one to be less than ideal.

 

[Ron Gray]

Looks a bit better now.

 

[Ron Gray]

Well, as promised, here is the video from today's flight which, I hasten to add didn't go according to plan. To cut a long story short, I was finding it difficult to control on elevator in fact even on high rates I didn't have enough throw. Similarly the engine started to misbehave in flight which I put down to a bad tune. The landing was a bit of a disaster due to a lack of both elevator and rudder control, well there was some but no enough and not when I wanted it, as you will see. Anyway the damage is only very slight, prop damaged (not broken) and both wheel axles bent. As you will see from the video it also has a tendency to climb under throttle so that needs fixing!

 

On closer inspection I found that the servo tray which holds the Elevator, Rudder and Throttle servos had come loose (it wasn't glued in place, it was screwed!!!!) which meant that the pull pull tension for both Elevator and Rudder was somewhat missing and relied on the push rod for the servo and that of the tailwheel steering to hold everything in place, or not.

 

The good thing is that the C of G is correct and the 200 in-line has more than enough power.

 

The video is uncut, apart from me cutting out the swearing at the end!!

 

 

[Peter Jenkins]

Well done Ron.  Shame about the servo tray.  It's always the little things that bite you isn't it!  Still, next time should be a much better experience.  Look forward to seeing it fly at some point.

 

Peter

[Ron Gray]

Thanks Peter, it was a very strange flight, most of which I was holding full down but when I wanted some up (landing) there wasn’t any there! So the flight was mostly aileron and a bit iffy throttle control! Still, glad there wasn’t any real damage. 

[Paul De Tourtoulon]

Nice flight, glued and screwed or just maybe a few more screws?, sounds really nice.

[Ron Gray]

My mistake Paul, screws only, no glue. Problem now resolved!

[Paul De Tourtoulon]

A "Cheap" if not painful lesson,,,

[Chris Walby]

Overall a successful day with the Hurricane there Ron and back on the ground with little damage considering. Any ideas as to the cause of the misfire and with the gear tray fixed it shouldn't be too far off another go.

 

Seems to fly well enough and certainly covers the ground at a good rate of Knots.

 

Did it pitch change with UC or flaps much (couldn't tell if you landed with flaps)?

[Ron Gray]

Yes Chris, more + than -. My feeling about the backfiring is that it was probably caused by the loose servo tray which caused it to have an erratic throttle, open then quickly closed (I know that I can provoke backfiring on some of my other Lasers by doing that!), but that is just my best guess, next flight should see if I'm right.

 

Regarding the performance, I never really got to run it with the throttle fully open either because of the climbing or because it just never went to full (loose servo tray) so I would say that the performance is 'sparkling', in fact I would go as far as to say that it feels better than the 200i in my Sportster and I can see me fitting a larger prop (currently APC 18x8).

 

No pitch change with UC but then I haven't got the doors on (my previous Hurri had quite a marked pitch down when the gear was down). I only used ½ flaps for the landing as it was quite windy and there was no noticeable pitch change with them deployed.

 

All of the damaged bits (bent axles, loose servo tray) have now been fixed and a new prop attached so all good to go again when the weather is suitable.